Oral Radiology

• Radiation Physics Question and Answers
• Properties of X Ray Question and Answers
• Production of X Ray Question and Answers
• Radiation Biology Question and Answers
• Radiation Protection Question and Answers
• X Ray Film & Accessories Question and Answers
• Film Processing Question and Answers
• Ideal Radiograph Question and Answers
• Faulty Radiographs Question and Answers
• Intraoral Radiographic Techniques Question and Answers
  • Intraoral Radiographic Techniques Long Essays
  • Intraoral Radiographic Techniques Short Essays
• Panoramic Radiography Question and Answers
• Occlusal Radiographs Question and Answers
• Object Localisation Techniques Question and Answers
• Specialized Radiographic Techniques Question and Answers
  • Specialized Radiographic Techniques Short Essays
  • Specialized Radiographic Techniques Notes
• Normal Anatomic Structures Question and Answers
• Periapical Radiolucency and Radiopacity Question and Answers
• Radiographic Interpretations Question and Answers
• Oral Radiology Miscellaneous Question and Answers

Oral Radiology Miscellaneous Short Essays

Question 1. Mass disaster
Answer.

Mass disaster

• With the complete reform of interstate and international travel, accidents are high and causing most of the disasters worldwide
• In the analysis of these incidences where children often become victims, the task of identification is very complicated
• The vast number of victims who are burnt, decomposed, and mutilated can be overwhelming
• These can be systemically examined and identified by the dentist

Question 2. Sunray appearance
Answer.

Sunray appearance

• It is a radiographic feature of larger lesions
• It may cause cortical expansion with radiating spicules at the expanding perphery
• This results in the sunray appearance of the lesions
• It is seen in
  • Osteosarcoma
  • Hemangioma
  • Osteoblastoma

Question 3. Moth-eaten appearance
Answer.

Moth-eaten appearance

• It is seen as radiolucent areas
• These areas enlarge
• Outline is irregular
• It gets separated by islands of normal-appearing bone
• This is due to the enlargement of medullary spaces and widening of Volkmann’s canals, secondary to lysis of bone and replacement with granulation tissue
• It is seen in
  • Early stage of osteosarcoma
  • Squamous cell carcinoma
  • Osteomyelitis
  • Leukemia
  • Malignant lymphoma

Question 4. Fracture of teeth
Answer.

Types

• Concussion:
  • There is a widening of periodontal ligament space at the apex
  • Presence of pulpal necrosis and periapical lesion
• Luxation:
  • Refers to dislocation or loosening of teeth due to loss of periodontal attachment
  • It can be
    • Intrusive
    • Extrusive
    • Lateral
  • Features:
    • Disruption of continuity of lamina dura in the apical region
    • Widening of periodontal ligament space in the periapical region
    • Presence of pulpal necrosis or calcification of pulp chamber
• Avulsion:
  • Refers to complete displacement of tooth from its socket
  • Radiographically it shows an empty socket

Radiographic Changes In Fracture Of Teeth:

• The radiolucent line between tooth segments
• Displacement of tooth fragments
• Disruption of the continuity of the tooth surface
• In case of root fracture, there may be a radiolucent line transversing the midportion of the tooth suggestive of fracture

Question 5. Lacerated wounds
Answer.

Features:

• Margins are irregular, ragged, and uneven and their extremities are pointed or blunt.
• Bruising is seen either in the skin or the subcutaneous tissues around the wounds
• Deeper tissues are unevenly divided with tags of tissue at the bottom of the wound bridging across the margin.
• Hair bulbs are crushed.
• Hemorrhage is less because the arteries are crushed and torn across irregularly.
• Foreign matter may be found in the wound.
• Depth varies according to the thickness of the soft parts and the degree of force applied.
• A laceration is usually curved.
• The skin on the side of the wound opposite to direction of force is usually torn free or undermined.

Question 6. Contrast radiography
Answer.

Contrast radiography

• Contrast radiography is a method of studying body organs using X-rays and the administration of a special dye, called contrast medium.
• The contrast medium will highlight the specific areas in the body and help them to be seen in greater X-ray on the x-ray image.
• Contrast medium can be given in different ways, depending on what organ or tissue needs to be examined.
• This test allows us to evaluate these structures that are not clear on conventional x-ray exams.

Types:

• Various types of contrast radiography are given for different reasons.
  • Intravenous pyelography, or IVP,
    • Allows to examine the urinary system, including kidneys, ureters, and bladder, and identify tumors, cysts, and stones.
  • Upper GI (gastrointestinal) and small bowel series
    • Used to examine your esophagus, stomach, and upper small intestine and identify ulcers, obstructions, tumors, or inflammations.
  • A barium enema, also called a lower GI series
    • Used to examine your colon and rectum and detect polyps, cancer, inflammation, and diverticula [pouches within the colon].
  •  Angiography
    • Angiograexaminationows to examination of blood vessels and various organs to detect obstructions, tumors, and other problems in the heart, lungs, kidneys, arms, and legs.
  • Cardiac catheterization
    • Used to evaluate the heart and its vessels.

Question 7. Professional negligence
Answer.

Professional negligence

• Professional negligence is a common law tort and broadly occurs when a professional fails to perform his responsibilities to the required standard.
• Professional negligence claims have become more common in recent years.
• This is due to a combination of factors including an increasing reliance upon professional advice, the complexity of work carried out, and a raised awareness of legal rights.
• Professional negligence is a subset of the general rules on negligence to cover the situation in which the defendant has represented him or herself as having more than average skills and abilities.
• The usual rules rely on establishing that a duty of care is owned by the defendant to the claimant, and that the defendant is in breach of the duty.
• The standard test of breach is whether the defendant has matched the abilities of a reasonable person.
• This specialized set of rules determines the standards against which to measure the legal quality of the services delivered by those who claim to be among the best in their fields of expertise.

Question 8. Child abuse
Answer.

Definition:

• It is defined as the non-accidental physical injury, minimal or fatal, inflicted upon children by persons caring for them
• It is an overact of commission of a physical, emotional, or sexual

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Types:

• Physical abuse
• Educational abuse
• Emotional abuse
• Sexual abuse
• Failure to thrive
• International drugging or poisoning
• Munchausen syndrome by proxy

Characteristics:

• There are no spontaneous smiles and almost no eye contact among abused children
• Lack of cleanliness
• Presence of short stature concerning age
• Malnutrition
• Overdressed children
• Periorbital ecchymosis, scleral hemorrhage, ptosis, deviated nasal septum, cigarette burn marks and hand slap marks
• Fractured anterior teeth

Short Answers

Question 1. Bite marks
Answer.

Definition:

• It is a mark caused by teeth alone or in combination with other oral parts or consists of teeth marks produced by the antagonist teeth which can be as two opposing arch marks

Classification:

• Depending on the blinding agent
  • Human
  • Animals
  • Mechanical
• Depending on the material bitten
  • Skin
  • Perishable items
  • Non-perishable items
• Depending on the degree of biting
  • Definite bite marks
  • Amorous bite marks
  • Aggressive bite marks

Characteristics:

• An elliptical or ovoid pattern containing tooth and arch marks
• Presence of 4-5 teeth marks reflecting the shape of their incisal or occlusal surfaces
• The presence or absence of each tooth
• The peculiar shape of each tooth
• Mesiodistal dimensions
• Arch form and size
• Relationship between the upper and lower jaws

Question 2. Battered baby syndrome
Answer.

Battered baby syndrome

• It is a disease in which children are physically abused.
• The battered child syndrome is a form of child abuse
• It is a child who shows clinical or radiographic evidence of lesions that are frequently multiple and involve mainly the head, soft tissues, long bones, and thoracic cage and cannot be unequivocally explained

Question 3. Identification and aging of the dead from teeth
Answer.

Identification and aging of the dead from teeth

• Some of the common identifying features of teeth are examined
• They are:
• Faulty development
• Faulty alignment
• Localized wear on certain teeth
• Missing teeth
• Aging is determined by
• Root calcification
• Stages of eruption

Question 4. Scope of Forensic Dentistry
Answer.

Scope of Forensic Dentistry

• Forensic dentistry is one of the most rapidly developing branches of forensic medicine
• It plays an important role in helping forensic experts identify the affected victims or criminals
• It contributes to supporting families to enable them to care for children more adequately and the society to develop sensitivity and skills for respectful and healthy personal relationship

Question 5. Determination of age in forensic dentistry
Answer.

Age is determined by

• Visual observation
  • Stages of eruption of dentition are looked for
  • Attrition of teeth with increasing age is used
• Radiography
  • Provide gross information on dental development of dentition
• Histological
  • Determines the stage of development of the dentition
• Physical and chemical analysis
  • Determine alterations in levels with age

Question 6. Sex determination
Answer.

Sex determination

• Identification of sex can be determined by
  • Examining the sexual organs of the victims or their secondary sexual characteristics
  • Examine sex chromosome
  • Identification of Bar body in buccal smear

Question 7. Lip prints
Answer.

. Lip prints

• Lip prints are used as an identification aid
• Minor differences have been observed between the right and left sides and between upper and lower lips
• Lip prints on drinking glasses, facial tissues, and magazines have been used as evidence in actual court cases also
• The science of examining lip prints is called coloscopy

Types Of Lip Prints:

• Vertical
• Branched
• Intersected
• Reticular pattern

Question 8. Coolidge’s tube
Answer.

Coolidge’s tube

• In 1913, William David Coolidge invented the Coolidge tube, an X-ray tube with an improved cathode for use in X-ray machines that allowed for more intense visualization of deep-seated anatomy and tumors.
• The Coolidge tube, which also utilized a tungsten filament, was a major development in the then-nascent medical specialty of radiology, and its basic design is still in use.
• He invented the first rotating anode X-ray tube.
• The Coolidge tube, also called the hot cathode tube, is the most widely used.
• It works with a very good quality vacuum (about 10-4pa, or 10-6 Torr).
• In the Coolidge tube, the electrons are produced by the thermionic effect from a tungsten filament heated by an electric current.
• The filament is the cathode of the tube.
• The high voltage potential is between the cathode and the anode, the electrons are thus accelerated and then hit the anode.

Panoramic Radiography Important Notes

• The areas, which are not visible in O.P.G are:
  • Mandibular canine area
  • Coronoid process
  • Anterior body of mandible

Panoramic Radiography Long Essays

Question 1. Describe the principle, indication, and limitations of panoramic radiographs.
Or
Describe the principles of panoramic radiography. Enumerate its indications and limitations
Answer.

Panoramic Radiographs Principle:

• This is based on the curvilinear variant of conventional tomography
• The movement of the tube head and the film produces an image through the process known as “tomography”
• Curvilinear tomography is also based on the principle of reciprocal movement of an X-ray source and an image receptor around a central point or plane called an image layer

Panoramic Radiographs Indications:

• As a substitute for full mouth intraoral periapical radiograph
• For evaluation of tooth development for children, the mixed dentition and also the aged
• To assist and assess the patient for and during orthodontic treatment
• To establish the site and size of lesions
• Prior to any surgical procedures
• Forthe  detection of fractures
• For follow-up of treatment, progress of pathology or prostoperative bony healing
• Investigation of TMJ dysfunction
• To study the antrum
• For overall view of the alveolar bone levels
• Assessment of underlying bone diseases
• Evaluation of developmental anomalies
• Evaluation of bone level before inserting implants

Panoramic Radiographs Limitations:

• Areas of diagnostic interest outside the focal through may be poorly visualized
• Poor diagnostic value in terms of magnification, distortion, loss of details
• There is overlapping of teeth in the bicuspid area of the maxilla and mandible
• In cases of pronounced inclination, the anterior teeth are poorly defined
• The density of spine causes lack of clarity in central portion of the film
• Formation of ghost images due to soft tissue shadows and air spaces

Panoramic Radiography Short Essays

Question 1. OPG.
Or
Note on panoramic imaging
Or
Panoramic radiography
Answer.

OPG Definition:

• It is a technique for producing a single tomographic image of the facial structures that induces both the maxillary and mandible dental arches and their supporting structures

OPG Principle:

• This is based on curvilinear variant of conventional tomography
• The movement of the tube head and the film produces an images through the process known as “tomography”
• Curvilinear tomography is also based on the principle of reciprocal movement of an X-ray source and an image receptor around a central point or plane called as image layer

OPG Procedure:

• Explain the procedure to the patient
• Make the patient to remove all the accessories that may interfere with the image
• Position the patient such that he is in the focal through
• Instruct the patient to look straight
• Patient is positioned such that dental arches are located in the middle of the focal through
• Occlusal plane is adjusted such that the Frankfort plane is parallel to the floor
• This is done by placing central incisor into a notched incisal device with lead marker
• Center the lower border of mandible on the chin rest and is equidistant
• Instruct the patient to position the tongue on the palate
• Exposure the film
• Process it as usual

Question 2. Advantages and disadvantages of orthopantomograph
Answer.

Orthopantograph:

• It is a technique for producing a single tomographic image of the facial structures that induces both the maxillary and mandible dental arches and their supporting structures

Orthopantograph Advantages:

• Broad coverage of facial bones and teeth
• Low radiation dose
• Ease of apnoramic radiographic technique

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• Can be used in patients with trismus or in patients who cannot tolerate intraoral radiography
• Quick and convenient technique
• Useful visual aid in patient education and case presentation

Orthopantograph Disadvantages:

• Resolution is very low
• Cannot be used in the diagnosis of caries
• Cannot be used in the evaluation of bone loss due to periodontal diseases
• Shows superimposition, especially in the premolar region
• Structures outside the image layer cannot be visualized
• Cannot be used as substitute to intraoral radiography
• Magnification across image is unequal
• Requires accurate patient positioning to avoid positioning errors and artifacts
• Difficult to image both jaws when patient have severe maxillomandibular discrepancy

Panoramic Radiography Short Answers

Question 1. Principle of panoramic imaging.
Answer.

Panoramic Imaging Principle:

• This is based on curvilinear variant of conventional tomography
• The movement of the tube head and the film produces an images through the process known as “tomography”
• Curvilinear tomography is also based on the principle of reciprocal movement of an X-ray source and an image receptor around a central point or plane called as image layer

Question 2. Advantages of OPG
Answer.

Advantages of OPG

• Broad coverage of facial bones and teeth
• Low radiation dose
• Ease of apnoramic radiographic technique
• Can be used in patients with trismus or in patients who cannot tolerate intraoral radiography
• Quick and convenient technique
• Useful visual aid in patient education and case presentation

Question 3. OPG – indications
Answer.

OPG – indications

• As a substitute for full mouth intraoral periapical radiograph
• For evaluation of tooth development for children, the mixed dentition and also the aged
• For assist and assess the patient for and during orthodontic treatment
• To establish the site and size of lesions
• Prior to any surgical procedures
• For detection of fractures
• For follow up of treatment, progress of pathology or prostoperative bony healing
• Investigation of TMJ dysfunction
• To study the antrum
• For overall view of the alveolar bone levels
• Assessment of underlying bone diseases
• Evaluation of developmental anomalies
• Evaluation of bone level before inserting implants

Panoramic Radiography Viva Voce

• 3 centers of rotation are there in OPG
• Radiation exposure is less for panoramic radiography compared to CT scan. It is highest for arthography.
• In panoramic radiograph smiling or appearance of structures is seen if patients chin is tilted downward.
• Frowning appearance is seen if patient’s chin is tilted upwards

Occlusal Radiographs Important Notes

• Lateral oblique projections

Occlusal Radiographs Long Essays

Question 1. What are the indications for occlusal radiographs? Describe radiographic technique in taking maxillary and mandibular cross sectional occlusal radiograph.
Or
What are the indications for occlusal radiographs? Describe radiographic technique in taking maxillary and mandibular topographic occlusal radiograph.
Answer.

occlusal radiograph Indications:

• To locate retained roots of extracted teeth
• To locate supernumerary, unerupted or impacted teeth
• To locate foreign bodies in the jaw
• To locate salivary stones in ducts of submandibular gland
• To locate and evaluate the extend of the lesion
• To evaluate boundaries of the maxillary sinus
• To evaluate fractures of the maxilla and mandible
• To aid in examination in patient with trismus
• To examine area of cleft palate
• To measure changes in the size and shape of the maxilla and mandible
• For determining the bucco/palatal position of unerupted canines

Maxillary Cross Sectional View:

• Image Field:
  • It shows palate
  • Zygomatic process of the maxilla
  • Anterior inferior aspects of each antrum
  • Nasolacrimal canals
  • Teeth from right second molar to left second molar
  • Nasal septum
• Film Placement:
  • The film is placed crosswise into the mouth and gently pushed back until it contacts the anterior border of the rami
• Projection of the Central Ray:
  • Angulation:
    • Vertical: +6°
    • Horizontal: 0°
  • Entry of central ray through the bridge of the nose

Mandibular Cross Sectional View:

• Image Field:
  • It shows
  • Soft tissues of the floor of the mouth
  • Delineates the lingual and Buccal plates of the jaw bone
  • Teeth from second molar to second molar
• Film Placement:
  • The film is placed in the mouth with its long axis perpendicular to the sagittal plane
  • The pebbled surface is towards the mandible
  • The anterior border of the film should be approxiamately 1/2 inch anterior to the Mandibular central incisors
• Projection of the Central Ray:
  • It is directed at right angles to the center of the film

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• • Point of entry:
    • Middle through the floor of the mouth
    • Approximately 3 cm below the chin

Question 1. Indications and technique for occlusal radiograph for topographical view.
Answer.

Indications and technique for occlusal radiograph for topographical view

Occlusal radiograph Basic Principles:

• Film is positioned with white side facing the arch being exposed
• Film is placed in the mouth between the occlusal surfaces of the maxillary and Mandibular teeth
• The film is stabilized when the patient gently bites on the surface of the film
• For maxillary occlusal films the patient’s head is positioned such that upper arch is parallel to the floor
• Mid sagittal plane should be perpendicular to the floor
• For Mandibular radiograph the patient’s head is retroclined such that the lower arch is perpendicular to the floor

Occlusal radiograph Film Used:

• Occlusal film is used
• Its dimensions are:
  • 57 x 76 mm

Object Localisation Techniques Long Essays

Question 1. Enumerate intra-oral radiographic techniques. Describe the procedure of localizing impacted left maxillary canine.
Answer:

Intra-Oral Radiographic Techniques:

• Intra-oral radiographic Techniques are:
  • Paralleling technique
  • Bisecting angle technique

Right Angle Technique:

• This is used to localize impacted left maxillary canine
• It is also called Miller’s right-angle technique
• It uses two radiographic projections taken at right angles to each other

Intra-Oral Radiographic  Technique:

• The periapical film is exposed using proper technique to show the position of the object in super inferior and anteroposterior relationship
• Next, occlusal film is exposed directing the central X-ray beam perpendicular to the film
• These two radiographs are compared

Intra-Oral Radiographic Uses

• Locates maxillary impacted canine
• Diagnoses fracture of the mandible
• Locates any displacement

Object Localisation Techniques Short Essays

Question 1. Object localization techniques.
Answer.

Object localization techniques

• Intraoral localization techniques are used to locate the position of a tooth object in the jaws
• Indications:
  • Foreign bodies
  • Impacted teeth
  • Unerupted teeth
  • Retained roots
  • Salivary stones
  • Jaw fractures
  • Broken needles
  • Root position
  • Filling materials

Radiographic Techniques:

• Maxillary area
  • Incisor zone
    • Stereoscopic
    • Lateral profile
    • Occlusal
  • Cuspid zone
    • Stereoscopic
    • Lateral profile
    • Occlusal
  • Bicuspid and molar zone
    • Periapical
    • Occlusal
• Mandibular area
  • Incisor zone
    • Periapical
    • Lateral profile
    • Occlusal
  • Posterior zone
    • periapical
    • Occlusal
  • Third molar zone
    • Periapical
    • Lateral oblique
    • Oblique occlusal

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• Methods

Buccal and lingual objects shift positions when the direction of the X-ray beam is changed. A Buccal and lingual are superimposed in the original radiograph B If the tube head is shifted in the distal direction, the buccal object moves mesially and the lingual object moves distally (same direction = Lingual; Opposite Direction = Buccal)

 

The right angle technique A – The object appears to be located in bone on the periapical radiograph. B – The occlusal radiograph reveals that the object is located in the soft tissue lingual to the mandible

 

Right-angled localization technique. Two films are exposed at right angles to each other to identify the location of an object. The periapical radiograph A – will demonstrate the superior-inferior and anterior-posterior position of the objects. A cross-sectional occlusal radiograph B – will demonstrate the anteroposterior and buccal lingual positions. Thus these two radiographs will demonstrate all three dimensions of an area, and the location of objects can be identified

Question 2. Indications and interpretation of Clarke’s technique.
Answer.

Clarke’s Technique Indications:

• Foreign bodies
• Impacted teeth
• Unerupted teeth
• Retained roots
• Salivary stones
• Broken needles
• Jaw fractures
• Filling materials
• Root position

Clarke’s Technique Method:

• Two radiographs are taken
• The first one with proper technique and angulation
• The second radiograph is taken by either changing the vertical or horizontal angulation

Clarke’s Technique Interpretation:

• When the dental structure or object seen in the second radiograph appears to have moved in the same direction as the shift of the position-indicating device, the structure is said to be positioned lingually
• If the object appears to have moved in the opposite direction, then the object is said to be positioned buccally

Clarke’s Technique Slob Rule:

Buccal and lingual objects shift positions when the direction of the X-ray beam is changed. A – Buccal (cross-hatched circle and lingual (black circle) are superimposed in the original radiograph B – if the tube head is shifted in the distal direction, the buccal object moves mesially and the lingual object moves distally (same direction = Lingual; Opposite Direction = Buccal)

Object Localisation Techniques Short Answers

Question 1. SLOB technique.
Answer.

SLOB Technique Method:

• Two radiographs are taken
• The first one with proper technique and angulation
• The second radiograph is taken by either changing the vertical or horizontal angulation

SLOB Technique  Interpretation:

• When the dental structure or object seen in the second radiograph appears to have moved in the same direction as the shift of the position-indicating device, the structure is said to be positioned lingually
• If the object appears to have moved in the opposite direction, then the object is said to be positioned buccally

SLOB Technique  Slob Rule:

• Same side Lingual Opposite side Buccal:

Buccal and lingual objects shift positions when the direction of the X-ray beam is changed. A – Buccal (cross-hatched circle0 and lingual (black circle) are superimposed in the original radiograph B – if the tube head is shifted in the distal direction, the buccal object moves mesially and the lingual object moves distally (same direction = Lingual; Opposite Direction = Buccal)

Normal Anatomic Structures Short Essays

Question 1. Anatomical landmarks in the upper posterior periapical radiograph
Answer.

Anatomic Landmarks In the Maxillary Posterior Region Are:

• Maxillary sinus
• Inverted Y – configuration
• Maxillary tuberosity
• Hamular notch
• Medial and lateral pterygoid plates
• Zygomatic process
• Zygomatic bone

Question 2. Normal radiographic anatomy of teeth and supporting structures.
Answer:

Anatomic Landmarks In Maxillary Anterior Region Are:

• Incisive foramen
• Superior foramina of incisive canal
• Median palatine suture
• Lateral fossa
• Nasal fossa
• Nasal septum
• Floor of nasal cavity
• Anterior nasal spine
• Inferior nasal concha
• Nasolacrimal canal
• Nose
• Inverted Y

Read And Learn More: Oral Radiology Question and Answers

Anatomic Landmarks In the Maxillary Posterior Region Are:

• Maxillary sinus
• Inverted Y – configuration
• Maxillary tuberosity
• Hamular notch
• Medial and lateral pterygoid plates
• Zygomatic process
• Zygomatic bone

Anatomic Landmarks In the Mandibular Region

• Genial tubercle
• Nutrient canal
• Submandibular gland fossa
• Sublingual gland fossa
• Retromolar triangle.

Normal Anatomic Structures Short Answers

Question 1. Normal anatomical landmarks in the maxillary anterior region.
Answer.

Normal anatomical landmarks in the maxillary anterior region

Question 2. Radiographic appearance of the mandibular canal.
Answer.

The radiographic appearance of the mandibular canal

• Radiographically it appears as a radiolucent band
• It is outlined by two thin radiopaque lines that represent the cortical walls of the canal
• It may appear below or superimposed on the Mandibular molar teeth
• It extends from the Mandibular foramen to the mental foramen
• It houses the inferior alveolar nerve and the blood vessels
• It is a tube-like – passage through the bone that travels the length of the mandible

Question 3. Line of tennis.
Answer.

Line of tennis

• It is the intersection of the maxillary sinus and the nasal cavity
• On radiograph, it appears as
  • A radiopaque upside-down “Y” formed by the intersection of the floor of the nasal fossa and the anterior border of the maxillary sinus
  • It is located above the maxillary canine

Question 4. Lamina dura.
Answer.

Lamina dura

• This is the wall of the tooth socket that surrounds the tooth
• It is made up of dense cortical bone
• On radiograph, it appears as
  • A thin radiopaque line that surrounds the root of the tooth
  • It is continuous with the shadow of the cortical bone at the alveolar crest
  • It is slightly thicker than the trabeculae of the cancellous bone in the area
  • When the X-ray beam is directed through the relatively long expanse of the structure, the lamina dura appears radiopaque and well-defined
  • When the beam is directed more obliquely, the lamina dura appears more diffuse
  • The thickness and density of the lamina dura will vary with the amount of occlusal stresses
  • It is wider and more dense around the roots of teeth in heavy occlusion
  • It is thinner and less dense around teeth not subjected to occlusion function
  • A double lamina dura image appears if the mesial or distal surfaces of the roor present two elevations in the path of the X-ray beam
  • The presence of an intact lamina dura around the tooth indicates a vital pulp,
  • However ,in some cases I,ts absence may be normal

Question 5. Anatomical landmarks of maxillary
Answer:

Anatomic Landmarks In Maxillary Anterior Region Are:

• Incisive foramen
• Superior foramina of incisive canal
• Median palatine suture
• Lateral fossa
• Nasal fossa
• Nasal septum
• FThe floor of the nasal cavity
• Anterior nasal spine
• Inferior nasal concha
• Nasolacrimal canal
• Nose
• Inverted Y

Anatomic Landmarks In the Maxillary Posterior Region Are:

• Maxillary sinus
• Inverted Y – configuration
• Maxillary tuberosity
• Hamular notch
• Medial and lateral pterygoid plates
• Zygomatic process

Periapical Radiolucency And Radiopacity Important Notes

• Multilocular radiolucencies – 3 types
  • Soap bubble:- Individual compartments are circular, large and overlapped
  • Honeycomb:- Individual compartments are small, numerous, and equally spaced.
  • Angular:- Individual compartments are angular in shape
• Common lesions showing multilocular radiolucency:
  • Ameloblastoma
  • Odontogenic keratocyst
  • Odontogenic myxoma
  • Central giant cell granuloma
  • Central hemangioma
  • Aneurysmal bone cyst
  • Cherubism
• Ameloblastoma:
  • Soap bubble or honeycombed appearance
  • Most common in 3rd molar – ramus area
  • Nothing is seen in the advancing end of the tumor
  • Root resorption and displacement of adjacent teeth are seen
  • Rarely causes perforation
• Odontogenic Keratocyst:
  • Soap bubble appearance
  • No expansion of cortical plates, because the lesion grows anterior-posteriorly
• Odontogenic myxoma:
  • Exclusively seen in jaws, only in tooth-bearing portions
  • Angular or tennis racket or honeycomb appearance
  • May be found in association with impacted tooth

Periapical Radiolucency And Radiopacity Long Essays

Question 1. Enumerate periapical radiolucencies and opacities. How would you diagnose systemic diseases with periapical changes in radiographs?
Answer.

Periapical Radiolucencies:

• True periapical radiolucencies
  • Pulpoperiapical Radiolucencies:
    • Periapical granuloma:
    • Radicular cyst
    • Periapical scar
    • Chronic and acute dentoalveolar abscess:
    • Surgical defect
    • Osteomyelitis
    • Pulpoperiapical disease
  • Dentigerous Cyst
  • Periapical Cementosseous Dysplasis:
  • Periodontal Disease
  • Traumatic Bone Cyst
  • Non radicular Cyst
  • Malignant Tumors
• Rarities:
  • Ameloblastoma
  • Aneurysmal bone cyst
  • Cementifying and ossifying fibroma
  • Cementoblastoma – early stage
  • Giant cell granuloma
  • Leukemia

Periapical Radiopacities:

• True Periapical Radiopacities:
  • Condensing or sclerosing osteitis
  • Periapical idiopathic osteosclerosis
  • Periapical or focal cement osseous dysplasia
  • Unerupted succedaneous teeth
  • Foreign bodies
  • Hypercementosis
  • Rarities
  • Calcifying odontogenic cyst
  • Cementoossifying fibroma
  • Chondroma
  • Hematoma
  • Mature cementoblastoma
  • Osteogenic sarcoma
• False Periapical Radiopacities:
  • Anatomic structures
  • Impacted teeth
  • Tori, exostosis
  • Retained root tips
  • Foreign bodies
  • Mucosal cyst of the maxillary sinus
  • Ectopic calcification
  • Rarities
  • Calcified acne lesions
  • Calcified hematoma
  • Calcifying odontogenic cyst
  • Squamous cell carcinoma
  • Tonsilloliths

Systemic Diseases With Periapical Changes:

• Hyperparathyroidism:
  • There is a loss of lamina dura
  • Depending on the duration and severity, loss of lamina dura may occur around one tooth or all remaining teeth
  • Loss may be complete or partial
  • It results in a tapered appearance of the root
• Hypoparathyroidism:
  • Reveals dental enamel hypoplasia
  • External root resorption
  • Delayed eruption
  • Root dilaceration
• Hyperpituitarism:
  • Hypercementosis present over roots of posterior teeth
• Hypopituitarism:
  • Third molar buds are completely absent
• Hyperthyroidism:
  • Excessive bone resorption is seen
• Hypothyroidism:
  • Show periodontal disease, loss of teeth, and external root resorption
• Diabetes mellitus:
  • Presence of bone loss due to more prone to periodontal diseases
  • Results in focal sclerosing osteomyelitis or dry socket
• Cushing’s syndrome:
  • Teeth may erupt prematurely
  • Partial loss of lamina dura may occur

Read And Learn More: Oral Radiology Question and Answers

• Osteoporosis:
  • Thinning of the inferior mandibular cortex
  • Reduction in the number of trabeculae
• Rickets:
  • Enamel hypoplasia
  • Involves both unerupted and erupted teeth
  • Lamina dura and cortical boundary of tooth follicles may be thin or missing
• Renal Osteodystrophy:
  • Hypoplasia and hypo calcification of teeth
  • Results in loss of enamel
  • Lamina dura may be absent or less apparent
• Hypophosphatemic rickets:
  • Teeth are poorly formed with thin enamel caps large pulp chambers and root canals
  • Presence of periapical and periodontal abscesses
  • Subsequent pulp necrosis may be present
  • Lamina dura may become sparse
  • Cortical boundaries around tooth crypts may be thin or absent
• Hypophosphatasia:
  • Both primary and permanent teeth have thin enamel layers large pulp chambers and root canals
• Osteopetrosis:
  • Teeth are poorly calcified
  • Ankylosis is seen
  • Lamina dura and cortical borders may appear thicker than normal
• Systemic sclerosis:
  • Increase in width of periodontal ligament spaces around teeth
  • Both anterior and posterior teeth are affected
• Sickle cell anemia:
  • Thinning of cortical plates
• Thalassemia:
  • Thinning of cortical borders
  • Enlargement of marrow spaces
  • Trabeculae are large and coarse
  • Lamina dura is thin and the roots of teeth may be short

Question 2. Describe differential diagnosis of radiolucencies on the coronal part of teeth
Answer.

Pericoronal Radiolucencies:

With radiopaque flecks

• Ameloblastic fibro – odontoma
• Adenomatoid odontogenic tumor
• Calcifying epithelial odontogenic tumor
• Calcifying odontogenic cyst

Without radiopaque flecks

• • Normal follicular space
  • Osteitis with pericoronitis
  • Dentigerous cyst
  • Ameloblastic fibroma

Question 3. Describe the differential diagnosis of radiolucent lesions in the posterior part of the body of the mandible.
Answer.

Radiolucent Lesions In the Posterior Part Of The Body Of the Mandible:

• Traumatic bone cyst
• Odontogenic keratocyst
• Ameloblastoma
• Cherubism
• Odontogenic myxoma
• Aneurysmal bone cyst
• Central hemangioma

Question 4. Discuss the differential diagnosis of periapical radiolucencies.
Answer.

True periapical radiolucencise:

• Pulpoperiapical Radiolucencies:
  • Periapical granuloma:
    • The lesion has well-circumscribed radiolucency
    • It is somewhat rounded surrounding the apex of the tooth
    • This may have thin radiopaque borders
    • The involved may show deep restorations, extensive caries, fractures, or narrower pulp canals
    • Its size is less than 2.5 cm in diameter
  • Radicular cyst:
    • It appears as a round or pear-shaped radiolucency at the apex of a nonvital tooth
    • The radiolucency is more than 1.5 cm, but less than 3 cm in diameter, with a well defined hyperostotic borders
    • The margins are smooth, well-defined, well-etched and continuous
    • A radiopaque line of corticated bone is seen surrounding it
    • The radiopaque border is continuous with lamina dura
    • It may cause resorption of the roots
    • The adjacent teeth are displaced
    • There may be Buccal expansion
    • There may be displacement of the antrum
  • Periapical scar:
    • A well-circumscribed radiolucency, that is smaller than granuloma and cyst
    • The scar is constant in size
  • Chronic and acute dentoalveolar abscess:
    • The radiolucency may vary in size from small to quite large
    • The initial lesion may even cause expansion of the jaws
    • The margins may vary from well-defined to poorly defined-borders
    • The involved tooth may show deep restorations, caries, narrowed pulp canals
    • The roots may even show resorption
  • Surgical defect:
    • The radiolucency is usually rounded
    • It is smooth-contoured
    • It has well-defined borders
    • It usually doesn’t measure more than 1 cm in diameter
    • The radiolucency usually decreases in size
  • Osteomyelitis:
    • The density of the Involved bone is decreased
    • Loss of sharpness of trabeculae
    • Outline becomes blurred
    • Gradually solitary or multiple radiolucent areas may be seen on the radiograph representing enlarged trabeculae spaces
    • Saucer saucer-shaped area of destruction with irregular margins with teeth and some supporting bone is seen
    • Inflammatory exudates may lift the periosteum, which is seen as a radiopaque line adjacent to and almost parallel or slightly convex to the surface
    • There is a loss of continuity of lamina dura
  • Pulpoperiapical disease:
    • These appear as gray shadows that may be dome-shaped in the maxillary floor or a gray radiopacity that appears as a cap over the adjacent root
    • The margin is usually smooth contoured and distinct
• Dentigerous Cyst:
  • It appears as well defined radiolucent lesion with a hyperostotic border associated with the crown of unerupted teeth
  • It is usually unilocular
  • It may envelop the crown symmetrically or may expand laterally
  • The associated tooth may be displaced
  • The outline of the larger cyst may expand from the ramus into the coronoid process or the condyle
  • There may be resorption of the adjacent teeth
  • Types:
    • Central
      • The crown is enveloped symmetrically
    • Lateral
      • Cyst results from the dilatation of the follicle on one aspect of the crown
    • Circumferential
      • This entire tooth is surrounded by the cyst
• Periapical Cementosseous Dysplasia:
  • In the early stage, it occurs as radiolucencies that are usually somewhat rounded
  • They have well-defined borders
  • They are associated with vital pulp
  • The lesions may be solitary or multiple
  • They exceed 1 cm in diameter
• Periodontal Disease:
  • Radiolucency is caused by advanced bone loss
  • The entire bony support is lost
  • The tooth may appear as floating in the radiolucency
• Traumatic Bone Cyst:
  • The lesion exceeds size efficient to cause expansion of the cortical plates
  • This produces a bony hard bulge on the jaws
  • The lamina dura is intact
  • The radiolucency is well-defined
  • It is round to oval in shape
  • The lateral and inferior borders of the elongated variety have smooth, regular borders
• Non Radicular Cyst:
  • The most common structures seen are incisive canal cysts, median mandibular cysts, and primordial cyst
• Malignant Tumors:
  • It may be found as a single periapical radiolucency
  • Expansion of the jaw occurs in advanced conditions
  • The expansion has a smooth surface covered with a normal structure
• Rarities:
  • Ameloblastoma
  • Aneurysmal bone cyst
  • Cementifying and ossifying fibroma
  • Cementoblastoma – early stage
  • Giant cell granuloma
  • Leukemia

Periapical Radiolucency And Radiopacity Short Essays

Question 1. Differential diagnosis of periapical radiopacities.
Answer.

True Periapical Radiopacities:

• Condensing or sclerosingosteitis:
  • The lesion is of variable size with margins that are well-defined or diffuse
  • At the diffuse margins, the thickened trabeculae can be seen in continuation with the normal adjacent trabeculae
  • The image is seen outside the lamina dura and periodontal spaces outlining the root
• Periapical idiopathic osteosclerosis:
  • There may be solitary, multiple
  • It may be unilateral or bilateral
  • It may vary in size from 2 mm to cm in diameter
  • May have a round or irregular shape
  • The border may be distinct to indistinct, ragged, or blending with the adjacent bone
  • Commonly seen in the mandible
  • Sometimes deciduous molar roots are resorbed and replaced by sclerotic bone
• Peripheral or focal cement osseous dysplasia:
  • It is predominantly round or oval with smoothly contoured borders
  • It varies in diameter from 0.5 to 2 cm
  • The mature lesion is uniformly dense
  • It may have a thin radiolucent border
  • The border may be vague
  • Adjacent root shows hypercementosis
• Unerupted succedaneous teeth:
  • The crowns of permanent teeth represent radiopacity
  • Seen in patients under 12 or 13 years of age
• Foreign bodies:
  • Radiopaque foreign bodies in the peri-apex is usually root canal-filling material
• Hypercementosis:
  • The premolars are more often affected
  • It may be confined to just a small region on the root producing a nodule or the whole root may be involved
  • The altered shape of the root is apparent
  • The root is surrounded by a normal periodontal ligament space and lamina dura
  • On the anterior tooth, it may appear as a spherical mass of cementum attached to the root end
• Rarities:
  • Calcifying odontogenic cyst
  • Cementoossifying fibroma
  • Chondroma
  • Hamartoma
  • Mature cementoblastoma
  • Osteogenic sarcoma

False Periapical radiopacities:

• Anatomic structures:
  • It includes the anterior nasal spine, malar process, external oblique ridge, mylohyoid ridge, mental protuberance, and hyoid bone
  • Impacted teeth
    • It may be situated directly at the apex of an erupted tooth
  • Tori, exostosis,
    • It may appear as a single or multiple lesion
    • It is smoothly contoured, somewhat rounded, dense radiopaque masses
    • These are not circumscribed by periodontal ligament and lamina dura
  • Retained root tips
    • They are projected over the apex of adjacent teeth
    • The shape of the root, root canal, periodontal ligament, and lamina dura remain unaltered
  • Foreign bodies
    • Examples of such objects are metal fragments, zippers, hooks, jewelry, etc.
  • Mucosal cyst of the maxillary sinus
    • It appears relatively dense, dome-shaped mass with its base on the floor of the sinus
  • Ectopic calcification
    • It includes
    • Sialoliths
    • Rhinoliths
    • Antroliths
    • Calcified lymph nodes
    • Phleboliths
    • Anterial calcification
  • Rarities:
    • Calcified acne lesions
    • Calcified hematoma
    • Calcifying odontogenic cyst
    • Squamous cell carcinoma
    • Tonsilloliths

Question 2. Differential diagnosis of multiple punched-out radiolucencies.
Answer.

Multiple Myeloma:

• They are usually bilateral
• It is seen in the mandibular posterior region and ramus
• It arrears as a small rounded and discrete radiolucency having punched out appearance
• There may be numerous areas of bone destruction within the region of generalized radiolucency
• Some lesions have an oval and cystic shape
• It has well-defined margins
• The border may have a thin sclerotic rim
• It has well-defined margins
• The border may have a thin sclerotic rim
• The lesion may vary in size
• The teeth may appear too opaque
• The mandibular lesion may cause thinning of the cortical lower border

Cherubism

• It occurs bilaterally on rami
• The lesion grows slowly expanding but not perforating the cortex
• Usually, bony architecture returns to normal except for some that resemble ground glass appearance

Metastatic Carcinoma:

• It defined radiolucency
• It is seen in the mandible
• There may be multiple punched-out radiolucency when several nests of tumor cells are located close to each other
• There is a widening of PDL
• The cortical structures are destroyed

Periapical Radiolucency And Radiopacity Short Answers

Question 1. Periapical radiopacities.
Answer.

True Periapical Radiopacities:

• Condensing or sclerosing osteitis:
  • At the diffuse margins, the thickened trabeculae can be seen in continuation with the normal adjacent trabeculae
• Periapical idiopathic osteosclerosis:
  • May have a round or irregular shape
  • The border may be distinct to indistinct, ragged, or blending with the adjacent bone
  • Commonly seen in the mandible
• Periapical or focal cement osseous dysplasia:
  • It is predominantly round or oval with smoothly contoured borders
• Unerupted succedaneous teeth:
  • The crowns of permanent teeth represent radiopacity
  • Seen in patients under 12 or 13 years of age
• Foreign bodies:
  • Radiopaque foreign bodies in the periapex are usually root canal-filling material
• Hypercementosis:
  • It may be confined to just a small region on the root producing a nodule or the whole root may be involved
  • The altered shape of the root is apparent
• Rarities:
  • Calcifying odontogenic cyst
  • Cementoossifying fibroma
  • Chondroma
  • Hamartoma
  • Mature cementoblastoma
  • Osteogenic sarcoma

False periapical Radiopacities:

• Anatomic structures:
  • It includes the anterior nasal spine, malar process, external oblique ridge, mylohyoid ridge, mental protuberance, and hyoid bone
• Impacted teeth:
  • It may be situated directly at the apex of an erupted tooth
• Toxic, exostosis:
  • It is smooth contoured, somewhat rounded, dense radiopaque masses
• Retained root tips:
  • They are projected over the apex of adjacent teeth
• Foreign bodies:
  • Examples of such objects are metal fragments, zippers, hooks, jewelry, etc.
• Mucosal cyst of the maxillary sinus:
  • It appears relatively dense, dome-shaped mass with its base on the floor of the sinus
• Ectopic calcification:
  • It includes
  • Sialoliths
  • Rhinoliths
  • Antroliths
  • Calcified lymph nodes
  • Phleboliths
  • Arterial calcification
• Rarities:
  • Calcified acne lesions
  • Calcified hematoma
  • Calcifying odontogenic cyst
  • Squamous cell carcinoma
  • Tonsilloliths

Question 2. Radiographic features of cherubism
Answer.

Radiographic features of cherubism

• The involved area shows well-defined, multilocular, cyst-like radiolucent areas
• These often coalesce to form larger lesions
• Later stages cause severe bilateral expansion of the jaw with thinning of cortical plates
• Presence of ground-glass appearance
• Displacement of the inferior alveolar canal
• Multiple unerupted and displaced teeth appear
• Cortical perforations may occur

Radiographic Interpretations

Important Notes

• Some of the radiographic appearances in various pathology

• Central giant cell granuloma:
• • It is a reactive process, but not a neoplasm.
  • Soap bubble or honeycomb appearance
  • A characteristic feature is that the septa are perpendicular to the periphery of the lesion and notching is seen corresponding to the outline where the septa arise.
• Central hemangioma:
  • Soap bubble appearance
  • Swelling of jaws, and gingival bleeding through the sulcus are seen.
  • “Pumping action” is a characteristic clinical feature. If the tooth in the region of the tumor is pushed into the tumor, it will rebound back to the original.
• Aneurysmal bone cyst:
  • H/O of trauma, the cyst is a reactive process secondary to trauma
  • Honeycomb and soap bubble appearance
  • Frank’s blood on aspiration
  • Pseudocyst
  • Multinucleated giant cells are seen histologically
• Cherubism:
  • Seen at 2 – 6 years of age with familiar history
  • When the maxilla is involved, the skin over it is stretched with the pulling of skin below the eyes. The sclera is visible giving an “angelic look” or “eyes towards heaven”.
  • Multiple unerupted teeth are seen which appear to be floating in cyst-like spaces.
• Lesions arising from clinically missing or radiologically missing teeth:
  • Eruption cyst
  • Dentigerous cyst
  • Gorlin cyst
  • Unicystic or mural ameloblastoma
  • Adenoamelobastoma
  • Ameloblastic fibroma
  • Variants of ameloblastoma
    • Ameloblastic Odontoma
    • Ameloblastic Odontofibroma
    • Ameloblastic dentinoma
    • Ameloblastic dentinofibroma
  • Primordial cyst
  • Teratoma

Radiographic Interpretations Long Essays

Question 1. Describe the radiographic appearance of different cysts of the maxilla and mandible.
Answer.

Cysts Of Jaws:

• Odontogenic cysts:
• • Radicular cyst
  • Dentigerous cyst
  • Residual cyst
  • Odontogenic keratocyst
  • Calcifying odontogenic cyst
  • Primordial cyst
  • Globulomaxillary cyst
  • Median mandibular cyst
• Non – Odontogenic Cysts:
  • Incisive canal cyst
  • Nasoalveolar cyst
  • Median palatine cyst
  • Traumatic bone cyst
  • Aneurysmal bone cyst

Question 2. Describe the radiographic appearance of different stages of osteomyelitis of the jaw
Answer.

Osteomyelitis:

Early Acute:

• No radiographic changes are absorbed

Established Suppurative:

• The density of the involved bone is decreased
• Loss of sharpness of trabeculae
• Outline becomes blurred
• Gradually solitary or multiple radiolucent areas may be seen on the radiograph representing enlarged trabeculae spaces
• Saucer saucer-shaped area of destruction with irregular margins with teeth and some supporting bone is seen
• Inflammatory exudates may lift the periosteum, which is seen as a thin radiopaque line adjacent to and almost parallel or slightly convex to the surface
• There is a loss of continuity of lamina dura

Chronic Type:

• Multiple radiolucencies of variable size with irregular outlines and poorly defined borders are seen
• The bone gradually develops a moth-eaten appearance, as radiolucent areas enlarge and are separated by islands of normal bone
• Segments of the necrotic bone become detached and calcified and are called sequestra
• Sequestra are more dense and better defined due to sclerosis

Read And Learn More: Oral Radiology Question and Answers

• It often stimulates the formation of periosteal new bone which is seen as a single radiopaque or a series of radiopaque lines parallel to the surface of the critical bone gradually the radiolucent strip that separates the new bone from the outer cortical bone may be filled with sclerotic bone
• Roots may undergo resorption
• Lamina dura becomes less apparent
• The Fistula tract may appear as a radiolucent band

Radiographic Interpretations Short Essays

Question 1. Radiographic features of periodontal disease
Answer.

Early Or Mild Periodontitis:

• It is represented as an area of localized erosion of the alveolar bone crest
• In the anterior region, it is seen as the blunting of the alveolar crests
• In the posterior region, there may be a loss in the sharp angle between the lamina dura and the alveolar crest
• There is a loss of the cortical margins
• It appears rounded off with irregular diffuse margins

Moderate Periodontitis:

• The Buccal and lingual cortical plates are resorb
• There may be bone defects of bone between both plates
• It is seen as generalized horizontal bone erosion or localized angular defect

Horizontal Bone Loss:

• There is a loss of height of the alveolar bone with the crest still horizontal or parallel to the occlusal plane

Vertical Osseous Defect:

• These are localized lesions
• They appear as an oblique angulation of the alveolar bone in the area of the involved teeth

Types:

• Interproximal craters
• Proximal intrabony defect
• Two walled defects
• Interproximal hemisepta
• Inconsistent bony margins

Surrounding Internal Bone Changes:

• Peripheral bone may appear radiolucent due to loss of density and number of trabeculae
• The sclerotic bone appears as a dense amorphous radiopaque mass

Advance Or Severe Periodontitis:

• Extensive bone loss
• Excessive mobility
• Extensive osseous defects

Furcation Involvement:

• Bone resorption extending down the side of the multirooted tooth
• The thickening of the periodontal ligament space at the apex of the inter radicular bone crest
• The radiolucent image is sharply outlined between the roots
• The cortical plates appear more irregular

Aggressive Periodontitis:

Types:

• Localized juvenile periodontitis
• • Associated with attachment loss
  • Vertical bone loss with maxillary teeth (incisors & / molars)
  • There are arch or saucer-shaped defects with strong arch symmetry
• Generalized juvenile periodontitis
  • It may involve a variable number of teeth
  • A Rapid bone loss which may be of the vertical angular or horizontal pattern is seen
• Progressing periodontitis

Tooth Mobility:

• In the case of the single tooth, it may develop an hourglass-shaped
• In multirooted teeth, widening of periodontal space is seen

Question 2. Radiographic features of dental caries
Answer.

Dental Caries Types:

• Proximal Caries:
  Types:

• • Incipient proximal lesions:
    • It appears as a classical triangle with its broad base at the tooth surface spreading along the enamel rods
    • It appears as a notch, a dot, a band, or a thin line
  • Moderate proximal lesion:
    • These involve more than the outer half of the enamel
    • It doesn’t extend upto DEJ
    • Different appearances:
      • Triangular in shape with the base at the surface of the tooth
      • Diffuse radiolucent image
      • Combination of the above
  • Advanced proximal lesions:
    • These depict lesions invading the DEJ
    • It appears triangular and diffuse
    • This is the spreading of the demineralization process
    • Usually, the lesion does not spread beyond more than half the thickness of the dentine
• Pit And Fissure Caries:
  Types:

• • Incipient Occlusal Lesions:
    • These are not usually detected on the radiograph unless the lesion reaches the dentin
    • The only change is seen as a grey shadow just below the DEJ
  • Moderate Occlusal Lesions:
    • It appears as a broad base thin radiolucent zone in the dentine with little or no change apparent in the enamel
    • Occlusal caries in dentine appears as a band of increased opacity between the carious lesion and the pulp chamber
  • Severe Occlusal Lesions:
    • Depict large cavity in the crown
    • Pulp exposure is looked for
• Buccal/Facial/Lingual/Cervical Caries:
  • These occur in enamel pits and fissures
  • They appear as small round radiolucencies and become elliptical or semilunar as the lesion enlarges they have sharp well-defined borders
  • Surrounded by apparent radiolucency
  • If the lesion extends up to the distal line angle it may appear as a proximal caries
• Root Surface Caries:
  • It involves both cementum and dentin
  • It is common in mandibular molars and premolars
  • It appears as an “ill-defined saucer-like crater”
  • When the periphery surface is small it appears “notched”
• Rampant Caries:
  • Common in children with poor dietary habits and poor oral hygiene
  • It is seen as an extensive inter-proximal caries involving almost the whole of the primary dentine
• Recurrent Caries:
  • It develops at the margins of an existing restoration
  • A lesion next to the restoration may be distinguished from the radiopaque image of the restoration
• Nursing Bottle Caries:
  • The affected teeth are maxillary and Mandibular first permanent molars and the Mandibular canine
• Radiation Caries:
  • Appears as dark radiolucent shadows at the necks of teeth
  • It is more apparent in the mesial and distal aspects

Question 3. Radiographic appearance of odontoma.
Answer.

Radiographic appearance of odontoma

• Appears as well-defined radiolucencies with well-corticated borders
• Surrounded by a thin radiolucent zone representing a capsule
• • Compound – a bag of teeth appearance
    • Appears as numerous, small miniature teeth or tooth-like structures projecting from a single focus
    • Present between roots of erupted permanent teeth or above the crown of impacted teeth
  • Complex – sunburst appearance
    • Radiopaque mass within jawbone is present

Question 4. Radiographic appearance of fibrous dysplasia
Answer.

Radiographic appearance of fibrous dysplasia

• Initially, it produces unilocular or multilocular radiolucent areas in the bone
• Expansion and distortion of cortical plates occurs
• Displacement of teeth
• The egg-cell crackling of the cortex of the bone is present
• Later a classical ground glass or orange peel appearance of bone is seen
• The margin of the lesion blends with the surrounding normal bone
• Mandibular lesions cause bulging of the inferior borders
• Narrowing of periodontal ligament
• Thinning of lamina dura
• Maxillary lesions causes obliteration of maxillary sinus

Question 5. Radiographic appearance of hyperparathyroidism
Answer.

Radiographic appearance of hyperparathyroidism

• Radiodensity – Radiolucent lesion
• There may be a normal, granular, or ground-glass appearance
• Moth-eaten appearance with varying density
• Ostelitis fibrosa generalization – Localised bone destruction
• Brown tumor – represents ill-defined radiolucency
• Thinning of cortical tables
• Pepper pot skull
• Demineralization of the inferior border of the mandibular canal
• Thinning of outlines of the maxillary sinus
• Loss of lamina dura

Radiographic Interpretations Short Answers

Question 1. Radiographic features of ameloblastoma
Answer.

Radiographic features of ameloblastoma

• It develops in the Mandibular ramus region
• It may extend to the symphysis
• In the maxilla, it is more common in the third molar region and may extend into the maxillary sinus and nasal floor
• It has well defined corticated border which is curved and in small lesions, the border shape may be distinguishable from the cyst
• The internal structure varies:
• • Unilocular cyst-like appearance with a hyperostotic border
  • Area of bone destruction having smooth curved margins that are well defined, corticated, and situated within the cavity in an arrangement of coarse trabeculae
  • The thickness of the trabeculae varies from delicate strands to 2 mm width
  • In some large lesions, it is found that there is an almost complete loss of bony margins of the jaws
  • Multilocular cyst-like appearance which shows multiple cystic cavities with thin septae
  • The presence of cysts bunched together

Question 2. Radiographic features of OKC
Answer.

Radiographic features of OKC

• The radiographic appearance of odontogenic keratocyst shows aggressive growth with undulating borders, cloudy interiors, and the presence of internal septa which may give a multilocular appearance
• The margins are hyperstatic
• The size may vary from 5 cm to more in diameter
• They are usually oval shape
• It may expand and perforate the lingual and Buccal cortical plates
• Causes expansion of them
• It causes downward displacement of the inferior alveolar canal and resorption of the lower cortical plate of the mandible
• As it enlarges it may produce deflection of the unerupted teeth
• Root resorption may be seen

OKC Types:

• Envelopment
• • This embraces an adjacent unerupted teeth
• Replacement:
  • This forms in the place of normal teeth
• Extraneous
  • These are in the ascending ramus away from the teeth
• Collateral
  • These are adjacent to the roots of teeth

Question 3. Radiographic features of osteogenic sarcoma
Answer.

Radiographic features of osteogenic sarcoma

• The mandible is more frequently involved
• Common sites are the body of the mandible and the alveolar ridge
• The bony lesion is radiolucent with poorly defined, ragged borders
• Widening of PDL space
• Unusual unilateral bone resorption
• Cemental resorption
• Widening of the mandibular canal
• Early in the course of the disease, it is usually located centrally in the jaws
• Sometimes, it appears as a radiolucency in the periapex or more toward the periphery of the ridge or cortical plates
• It may originate adjacent to or seemingly in the periodontal space

Question 4. Radiographic features of proximal caries
Answer.

Proximal Caries Types:

• Incipient proximal lesions:
• • It appears as a classical triangle with its broad base at the tooth surface spreading along the enamel rods
  • It appears as a notch, a dot, a band, or a thin line
• Moderate proximal lesion:
  • These involve more than the outer half of the enamel
  • It doesn’t extend up to DEJ
  • Different appearances:
    • Triangular in shape with the base at the surface of the tooth
    • Diffuse radiolucent image
    • Combination of the above
• Advanced proximal lesions:
  • These depict lesions invading the DEJ
  • It appears triangular and diffuse
  • This is the spreading of the demineralization process
  • Usually, the lesion does not spread beyond more than half the thickness of the dentine

Question 5. Radiographic features of periapical granuloma
Answer.

Radiographic features of periapical granuloma

• Periapical area is radiolucent with loss of lamina dura
• The radiolucency may be of variable size at the apex of the tooth, usually of a diameter less than 1.5cm
• The lesion may or may not have a well-defined border
• There is a loss of lamina dura and periapical bone which is called “Periapical rarifying osteitis”
• The involved tooth may show a deep restoration, extensive caries, fracture, or a narrow pulp canal with nonvital pulp

Question 6. Radiological appearance of periapical cemental dysplasia
Answer.

Radiological appearance of periapical cemental dysplasia

The radiographic appearance of periapical dysplasia varies in different stages of the disease

• Osteolytic stage:
• • The lesion presents as a small, well-defined, radiolucent area near the apex of the involved tooth
  • Radiolucency is present in continuation with the periodontal ligament space
• Cementoblastic stage:
  • The lesion appears as a radiolucent area containing multiple small radiopaque foci
• Mature stage:
  • Present as well well-defined radiopaque mass at the root apex, being surrounded by a thin radiolucent zone

Question 7. Garre’s osteomyelitis
Answer.

Garre’s osteomyelitis

• Presents as a mottled radiolucent lesion with few radiopaque foci
• The cortex of bone exhibits many concentric or parallel opaque layers giving onion skin appearance
• It shows focal overgrowth of bone on the outer surface of the cortex
• Described as a duplication of the cortical layer of bone
• Few newly formed bony trabeculae are oriented perpendicular to onion skin layers

Question 8. Radiological appearance of fibrous dysplasia
Answer.

Radiological appearance of fibrous dysplasia

• Initially, it produces unilocular or multilocular radiolucent areas in the bone
• Expansion and distortion of cortical plates occurs
• Displacement of teeth
• The egg-cell crackling of the cortex of the bone is present
• Later a classical ground glass or orange peel appearance of bone is seen
• The margin of the lesion blends with the surrounding normal bone
• Mandibular lesions cause bulging of the inferior borders
• Narrowing of periodontal ligament
• Thinning of lamina dura
• Maxillary lesions causes obliteration of maxillary sinus

Question 9. Radiological appearance of Paget’s disease
Answer.

Radiological appearance of Paget’s disease

• Initially, there is the presence of radiolucent areas in the affected bone
• In the next stage, involved bone shows haphazardly arranged newly formed bone in radiolucent areas
• This produces the cotton wool appearance
• Radiopacity of lesions increases due to increased osteosclerosis
• Obliteration of maxillary sinus
• Hypercementosis of tooth
• Loss of lamina dura
• Obliteration of periodontal ligament space
• Root resorption

Question 10. Multilocular radiolucencies of jaws
Answer.

Multilocular radiolucencies of jaws

Multilocular radiolucencies of jaws are

• Odontogenic keratocyst
• Ameloblastic
• Central giant cell granuloma
• Cherubism
• Odontogenic myxoma
• Aneurysmal bone cyst
• Central hemangioma of bone

Question 11. Onion peel appearance
Answer.

Onion peel appearance

• It demonstrates multiple concentric parallel layers of new bone adjacent to the cortex
• The layers are thought to be the result of periods of variable growth
• It can be seen with
• • Osteosarcoma
  • Acute osteomyelitis
  • Ewing sarcoma
  • Langerhans cell histiocytosis

Question 12. Moth eaten appearance
Answer.

Moth eaten appearance

• It describes multiple small endosteal lucent lesions often with poorly defined margins
• Consists of multiple scattered holes that vary in size and arise separately
• These holes coalesce to form larger areas of bone destruction
• It is a bone marrow process
• It is seen in
• • Multiple myeloma
  • Primary bone lymphoma
  • Ewing sarcoma
  • Infection
  • Eosinophilic granuloma
  • Malignant fibrous histiocytoma
  • Metastases

Question 13. Sunburst appearance
Answer.

Sunburst appearance

• Sunburst appearance is a type of periosteal reaction giving the appearance of a sunburst secondary to an aggressive periostitis
• It occurs when the lesion grows too fast and the periosteum does not have enough time to lay down a new layer
• In such cases, the Sharpey’s fibers become stretched out perpendicular to the bone
• When these fibers ossify, they produce a pattern called a sunburst appearance
• It is frequently associated with osteosarcoma

Radiographic Interpretations Viva Voce

• A dentigerous cyst is associated with the crown of unerupted teeth
• The most common site for the occurrence of nasopalatine canal cyst is the maxillary central incisor
• AOT is commonly associated with an unerupted tooth

Specialized Radiographic Techniques Important Notes

• Xero radiography uses photoconductive selenium plates instead of film.
  • It produces images with high contrast, resolution, edge, enhancement, positive and negative display.
• Computer tomography (Axial tomography or computerized axial transverse scanning)
  • CT scanner consists of a radiographic tube that emits a finely collimated fan-shaped X-ray beam that is directed to a series of scintillation detectors or ionization chambers.
  • The CT image is recorded and displayed as a matrix of individual blocks called voxels.
  • Each square of the image matrix is called a pixel.
  • For image display each pixel is assigned with a CT number representing density.
  • These numbers are also known as Hounsfield units, which may range from – 1000 to +1000
  • Each constitutes a different level of optical density.
  • To convert a two-dimensional CT image into a three-dimensional CT image, each rectangular solid voxel is dimensionally altered into multiple cuboidal voxels.
  • This process is called INTERPOLATION.
  • IT Creates sets of evenly shaped cuboidal voxels (Aubervilliers) that occupy the same volume as the original voxel.
  • Computed tomography is useful in evaluating structures in and adjacent to salivary glands.
  • It distinguishes both soft and hard tissues as well as minute differences in soft tissue densities.
  • It is useful in assessing acute inflammatory processes and abscesses as well as cysts, mucoceles, and neoplasias.
• Salivary gland radiology:
  • Arcelin: Introduced sialography in 1913. Jacobvisi introduced the sialography technique.
  • Contrast agents used in sialography are
    • Water soluble – Eg: Pyridone, Singoaffin
    • Fat-soluble – Eg: Lipidiol, Ethiodol
  • Water-based contrast agents are used for chronic inflammatory lesions
  • Oil-based contrast agents are used in neoplasms.
  • Different projection after injection of contrast agent.
• Nuclear medicine/ scintigraphy provides a functional study of salivary glands.
  • The isotope used in the technique is “99 Tc – per technetate”.
  • All major salivary glands can be studied at once by scintigraphy.
  • It is especially advantageous for conditions in which sialography is contraindicated as well as for patients whose ducts can not be cannulated.
• Ultrasonography is a relatively inexpensive, widely available painless, easy-to-perform, and non-invasive technique.
  • The primary application of ultrasonography is for the differentiation of solids from cystic ones.
• Radiographic techniques

Read And Learn More: Oral Radiology Question and Answers

Specialized Radiographic Techniques Short Answers

Question 1. Indications and contraindications of sialography.
Answer.

Indications:

• Detection of calculus or foreign bodies
• Determination of the extent of destruction of the gland secondary to obstructing calculi or foreign bodies
• Detection of fistula, diverticula, or strictures
• Determination and diagnosis of recurrent swellings and inflammatory processes
• Demonstration of a tumor and the determination of its location, size, and origin
• Selection of a site for biopsy
• Outline of the plane of the facial nerve
• Detection of residual stones
• Sialography can be used for therapeutic procedures

Contradictions:

• Patients with known sensitivity to iodine
• During the presence of acute inflammation
• It may interfere with subsequent thyroid function tests

Question 2. Technique for transcranial view of TMJ
Answer.

Transcranial projection:

Structure Seen:

• Useful in detecting arthritis of the articular surfaces
• To evaluate the joint’s bony relationship

Film Position:

• The cassette is placed against the patient’s ear and centered over the TMJ of interest
• It is placed parallel to the sagittal plane

Patient’s Position:

• The sagittal plane must be vertical
• The ala tragus line should be parallel to the floor
• The view is taken with
  • Open mouth
  • Rest position
  • Closed mouth

Central Ray:

• It differs according to the technique
  • Postauricular
    • Point of entry is 1/2 “behind and 2” above the auditory meatus
  • Grewcock approach
    • The path of entry is through point 2 above the auditory meatus
  • Gill’s approach
    • Point of entry is 1/2 “anterior and 2” above the auditory meatus
  • Angulation: +20º To +25º
  • Point Of Exit: TMJ of interest

Question 3. Indication of sub mento vertex view.
Answer.

Indication of sub mento vertex view

• To demonstrate the base of the skull
• To examine the position and orientation of the condyle and sphenoid sinus
• To reveal the fracture in the zygomatic arch of the maxilla
• To assess the medial and lateral pterygoid plates

Question 4. Radionuclide imaging.
Answer.

Method:

• Radioactive substances should be injected intravenously into the patient
• Rectilinear scanner or gamma scintillation camera records the gamma emission from the patient
• The camera uses a scintillation crystal that can fluorescence on interaction with gamma rays emitting from the radioactive substances
• The emitting light fluorescence is detected by a photomultiplier tube that magnifies and amplifies the signals many times to produce an image

Atom Used:

• Iodine
• Gallium
• Selenium
• Technetium

Question 5. Digital imaging.
Answer.

Digital imaging

• The use of digital technology results in a 50 to 90% reduction in patient radiation exposure because of the greater sensitivity of the digital receptor

Digital Imaging Types:

• Direct digital radiography
• Indirect digital radiography

Digital imaging Uses:

• It can be used to view the images where multiple images are required for analyzing
• In endodontic practice, the root canal length, working length, and distance between obturating material and the root apex
• In periodontics, to assess and measure the height of the alveolar bone
• It can be used in a patient who is un cooperative for regular radiographic techniques
• To evaluate the bony changes in the pathology of jaws
• To detect early dental caries

Question 6. Sialography – indications
Answer.

Sialography – indications

• Detection of calculus or foreign bodies
• Determination of the extent of destruction of the gland secondary to obstructing calculi or foreign bodies
• Detection of fistula, diverticula, or strictures
• Determination and diagnosis of recurrent swellings and inflammatory processes
• Demonstration of a tumor and the determination of its location, size, and origin
• Selection of a site for biopsy
• Outline of the plane of the facial nerve
• Detection of residual stones
• Sialography can be used for therapeutic procedures

Viva Voce

• Transpharyngeal projection is used for viewing the lateral surface of the condylar head and neck
• Reverse Towne’s projection is used for viewing the posterior aspect of both the condylar head and neck
• Selenium plate is used in xeroradiography
• Water’s view is used to view maxillary sinus

Question 1. Indications and Techniques for visualization of paranasal lsinuses.
Answer:

Paranasal lsinuses Indications:

• To study the relationship of the sinuses to each other and the surrounding structures
• To demonstrate the presence or absence of fluid in the sinuses

Paranasal lsinuses  Techniques:

• Posteroanterior [Granger] projection:
  • Structures Seen:
    • Inner and middle ear
    • Frontal sinuses
    • Anterior ethamoidal cells
    • Sphenoidal sinus
    • Upper part of antrum
  • Film Placement:
    • Midsagittal plane should be vertical
    • It should be perpendicular to the plane of the cassette
    • Only forehead and nose should touch the cassette
  • Central Ray:
    • It is directed to the midline of the skull
    • The beam passes through the canthomeatal plane perpendicular to the film plane

Diagram for the positioning for posteroanterior (Granger) projection

• Modified method, inclined posterior anterior [Caldwell projection]
  • Strucutures Seen:
    • Petrous ridges
    • Orbits
    • Ethamoidal cells
  • Film Placement:
    • Cassette is placed perpendicular to the floor
  • Position of the Patient:
    • Mid sagittal plane is perpendicular to the cassette
    • Only forehead and nose touches the cassette
    • Canthomeatal line is perpendicular to the cassette
  • Central Ray:
    • Directed 23º to the canthomeatal line
    • Enters the skull about 3 cm above the external occipital protuberance and exiting at the glabella

Diagram of the positioning inclined posteroanterior (Caldwell) projection

Question 2. Oblique lateral radiograph of mandible.
Answer:

• Anterior body of the mandible:
  • Structures Seen:
    • Anterior body of mandible
    • Position of teeth in that region
  • Film Placement:
    • Cassette is placed flat against the patient’s cheek
    • It is centered over the body of the mandible overlying canine
  • Position of the Patient:
    • The ala tragus line should be parallel to the floor
    • The mandible is protruded slightly
    • The inferior borderof the cassette should be parallel to the lower border of the mandible
    • The sagittal plane is tilted so that it is 5º to the vertical and rotated 30º from the true lateral position
    • The nose and chin should approximate the cassette
  • Central Ray:
    • Directed from 2 cm below the angle of the mandible opposite to the side of interest
    • The beam is directed upward -10º to -15º
    • It is centered on the anterior body of the mandible
    • The beam is directed perpendicular to the horizontal plane of the film

Diagram for the positioning of lateral oblique projection for anterior body of the mandible, film is in contact with the cheek at the canine area, and the X-ray beam aims at the canine area through radiographic key hole

• Posterior Body:
  • Structures Seen:
    • Body of the mandible
    • Position of teeth in that area
    • Ramus of the mandible
    • Angle of the mandible
  • Film Placement:
    • The cassette is placed against the patients cheek
    • It is centered over the body of the mandible
    • The cassette is placed parallel to the body of the mandible
  • Position of the Patient:
    • The ala tragus line is parallel to the floor
    • The mandible is protuded slightly
    • The inferior border of the cassette should be parallel to the lower border of the mandible and below it
    • The sagittal plane is tilted to 5º to the vertical
    • The head is rotated 10º to 15º from the true lateral position
  • Central Ray:
    • It is directed from 2 cm below the angle of the mandible opposite to the side of interest
    • The beam is directed upwards (-10º to -15º)
    • It is centered on the body of the mandible

Diagram for the positioning of lateral oblique projection for posterior body of the mandiblem film is in contact with the cheek at the premolar area, and the X-ray beam aims at the premolar area, through the radiographic key hole

• Ramus of Mandible:
  • Structures Seen:
    • Ramus from the angle of the mandible to the condyles
  • Film Placement:
    • The cassette is placed against the patients cheek
    • It is centered over the ramus of mandible
    • It should be parallel to ramus
  • Position of the Patient:
    • The ala tragus line should be parallel to the floor
    • The mandible is protruded slightly
    • The inferior border should be parallel to the lower border of the mandible and below it
    • The sagittal plane is tilted 10º to the vertical
    • The head is rotated 5º from the true lateral
  • Central Ray:
    • It is directed from 2 cm below the angle of the angle of the mandible opposite to the side of interest to a point posterior to the third molar region
    • The beam is directed upwards (-10º to -15º)
    • It is centered on the ramus of the mandible

Diagram from the positioning of PA water’s projection, the radiographic baseline is at 37º to the film, and the X-ray is perpendicular to the film

Question 3. Water’s projection.
Or
PA Water’s view.
Answer.

Water’s projection

• Structures Seen:
  • Maxillary sinus
  • Frontal sinus
  • Ethamoidal sinus
  • Orbit
  • Frontozygomatic suture
  • Nasal cavity
  • Coronoid process
  • Zygomatic arch
• Film Placement:
  • The cassette is placed perpendicular to the floor
• Position of the Patient:
  • The mid sagittal plane should be perpendicular to the plane of the film
  • The patient’s head is extended so that only the chin touches the cassette
  • The cassette is centered around the acanthion
  • The canthomeatal line should be 37º to the plane of the film
  • The line from the external auditory meatus to the mental protuberance should be perpendicular to the film
• Central Ray:
  • It is directed perpendicular and to the midpoint of the film
  • It enters from the vertex and exists from the acanthion

Diagram for the positioning of PA Water’s projection, the radiographic baseline is at 37º to the film, and the X-ray is perpendicular to the film

Question 4. Sialography.
Answer.

Sialography Technique:

• Identification of duct:
  • The parotid duct is located at the base of the papilla in the buccal mucosa adjacent to the first or second molar
  • The area over the mucosa should be dried with a small sponge
  • The submandibular duct orifice is situated on the submitting of the small papilla at the side of the lingual frenum
• Exploring of the duct:
  • The duct can be explore with lacrimal probe
  • In the case of the submandibular duct, the probe should pass through the length of the floor of the mouth to the level of the posterior border of the mylohyoid muscle i.e. about 5cm
  • Eversion of cheek should be done in case of parotid duct
  • By it, the duct is adequatly enlarged
• Introduction of cannula:
  • The sialographic cannula is inserted into the duct so that the tissue sop presses firmly into the orifice to prevent dye reflux
• Introduce contrasting media:
  • Liquid soluble or Water soluble agent is slowly introduced
• Amount of the agent:
  • Submandibular glandL 0.5 – 0.75ml
  • Parotid gland: 0.76 – 1ml
• Radiograph is taken:
  • Occlusal view/lateral oblique view is used to delineate the submandibular gland
  • A sialolith is better viewed in occlusal view
  • AP view it used for both the glands
  • It demonstrates the medial and lateral gland structures
• Evacuation:
  • After the radiograph is taken, the cannula should be removed
  • The patient is instructed to chew gum or the lemon slice and then asked to rinse
  • This is done to stimulate the gland and cause excretion of the dye.

Question 5. MRI – Principles and indications.
Answer.

MRI – Principles and indications

• It uses nonionizing radiation from the radiofrequency band of the electromagnetic spectrum

MRI Mechanism:

• The patient is placed inside a large magnet
• This induces a strong external magnetic field that causes the nuclei of many atoms in the body including hydrogen to align themselves with the magnetic field
• After application of radiofrequency signal, energy is released from the atoms that can be deteched and used to construct the image by computer

MRI Advantages:

• High sensitivity to detect tissue differences
• No radiation exposure hence no radiation affects the body
• Excellent imaging techniques especially for soft tissues
• It gives the best resolution of tissues of low inherent contrast

MRI Disadvantages:

• Long imaging times
• It gives the potential hazards in a patient with implanted metallic foreign objects like caradiac pacemakers, cerebral aneurysm clips.
• Some patients suffer from claustrophobia when positioned in a MRI machine.

MRI Indications:

• Diagnosing a suspected internal derangement of the TMJ
• Postsurgical evaluation of TMJ
• Identifying and localizing orofacial soft tissue lesions
• Provides the image of salivary gland parenchyma

Question 6. Scintigraphy.
Answer.

Scintigraphy

• It is based on the radiotracer method
• Radioactive atoms or molecules in organs behave in a manner identical to their counterpart in the body
• The radiotracers allow measurement of tissue function and provide early markers of disease through measurement of biochemical change in tissue before any physical signs and symptoms occur

Method:

• Radioactive substances should be injected innntravenously into the patient
• Rectilinear scanner or gamma scintillation camera records the gamma emission from the patient
• The camera uses a scintillation crystal that can fluorescence on interaction with gamma rays emitting from the radioactive substances
• The emitting light fluorescence is detected by a photomultiplier tube that magnifies and amplifies the signals many times to produce an image

Atom Used:

• Iodine
• Gallium
• Selenium
• Technetium

Read And Learn More: Oral Radiology Question and Answers

Scintigraphy Advantages:

• It is more sensitive to early or small changes in bone or salivary metabolism
• It has been used to detect the presence and size of tumors, metastasis, trauma and metabolic disorders

Scintigraphy Disadvantages:

• Poor, grainy image
• Confusion of normal inflammatory process with tumor and metastasis
• Patients also get exposed to a small quantity of radioactive material which causes biological changes in the tissues

Question 7. Digital radiography.
Answer.

Digital radiography

• The use of digital technology results in a 50 to 90% reduction in patient radiation exposure because of the greater sensitivity of the digital receptor
• Elimination of film processing and no need for dark room
• Considerable reduction in the time lapse between image acquisition and display

Digital radiography Mechanism:

• In digital imaging, the sensor is used i.e., CCD Charged Couple Device instead of radiographic film in the patient’s mouth
• After radiation exposure, the signal from the CCD is sent to the computer where it is digitalized into gray levels
• The image can then be displayed on a monitor, where it can be enhanced by varying the density and contrast
• The image may also be stored for future used

Digital radiography Types:

• Direct digital radiography
• Indirect digital radiography

Digital radiography Advantages:

• Eliminates the X-ray film, thereby reduces the cost of the film
• It serves as a recording, display, and storage for diagnostic images
• It requires less exposure time because of the grater sensitivity of the digit receptor there by preventing the patient from being exposed to radiation
• Eliminates the chemical processing and dark room so that preventing the cause of alllergy and pollution and also considerable reduction in time lapse between image acquisition and display
• Film contrast, density, brightness and color may be manipulated so that image information can be increased
• Reduction in the number of images that need to he remade because of over exposure or under exposure
• Transmission of image to remote sites in a digital format
• Image can be viewed on computer monitor to get an print out on paper

Digital radiography Disadvantages:

• Equipment is expensive
• Trained persons are required

Digital radiography Uses:

• It can be used to view the images where multiple images are required for analyzing
• In endodontic practice to measure the root canal length, working lenght and distance between obturating material and the root apex
• In perioidontics, to assess and measure the height of the alveoplar bone
• It can be used in a patient who is un cooperativge for regular radiographic techiniques
• To evaluate the bony changes in pathology of jaws
• To detect early dental caries

Question 8. Indications of CT [Computed tomography].
Answer.

Indications of CT [Computed tomography]

• Investigations of intracranial diseases including diseases tumors, hemorrhage and airfacts
• Investigations of suspected intracranial and spinal cord damage following trauma to the head and neck
• Assessment of fractures involving
  • Orbits and nasoethamodial complex
  • The cranial base
  • The odontoid peg
  • The cervical spine
• Tumor stagingassessement of site, size and extent of benign and malignant tumors affecting
  • The maxillary antra
  • The base of the skull
  • The pterygoid region
  • The pharynx
  • The larynx
• Investigations of tumors and tumor like discrete swellings intrinsic and extrinsic to the salivary glands
  • Investigation of the TMJ
  • Preoperative assessment of maxillary alveolar bone height and thickness before inserting implants

Question 9. Tranpharyngeal view
Answer.

Structures Seen:

• Medial surface of the condylar head and neck

Film Placement:

• The cassette is placed flat against the patient’s ear
• It is centered to a point 1/2″ anterior to the external auditory meatus, over the TMJ of interest

Position of the Patient:

• Sagittal plane should be vertical and parallel to the film
• The film is centered to a point 1/2 “anterior to the external auditory meatus
• The occlusal plane should be parallel to the transverse axis of the film
• The patient should open his mouth

Central Ray:

• It is directed from opposite side cranially at an angle of -5 to -10 degree posteriorly
• It is directed through the Mandibular notch of the opposite side below the base of the skull to the TMJ of interest

A – Tranpharyngeal projection. The central ray is orient superiorly 5º to 10º and posteriorly approximately 10º, centered over the TMJ of interest. The mandible is positioned at maximal opening

B – Tranpharyngeal projection, showing positioning from above, showing the X-ray beam aimed slightly posteriorly across the pharynx