Laboratory Procedures Prior To Try In Long Essays

Laboratory Procedures Prior To Try In Long Essays

Question 1. Define articulator. Give classification, and uses & discuss semi adjustable articulators.
Answer:

Articulator Definition:

“A mechanical device which, represents the temporomandibular joints & the jaw members to which maxillary & mandibular casts may be attached to stimulate jaw movements”.

Articulator Classification:

1. Based on theories:

• Bonwill theory articulator
• Conical theory articulator
• Spherical theory articulator

Read And Learn More: Prosthodontics Question And Answers

2. Based on the type of occlusal record used:

• Interocclusal record adjustment
• Graphic record adjustment

3. Based on the ability to stimulate jaw movements:

• Class 1
• Class 2
• Class 3
• Class 4

4. Based on adjustability:

• Nonadjustable
• Semi adjustable
• Fully adjustable

Uses:

• Diagnose the state of occlusion
• Planning of dental procedures
• Fabrication of restoration
• Correction of restoration
• Arrangement of artificial teeth

Semi-Adjustable Articulator:

They have adjustable horizontal condylar paths, adjustable lateral condylar paths, adjustable incisal guide tables & adjustable intercondylar distances

Types of Articulators:

•  Arcon Articulator:
  • In this type condylar element is attached to the lower member of the articulator & the condylar guidance is attached to the upper member
  • This resembles the TMJ.
• Advantages of Articulator: All relations are preserved even when the articular is open or closed
• Examples: Whip mix articulator:

• Non- Arcon Articulator:
  • This articulator have condylar element attach to the upper member
  • The condylar guidance is attach to the lower member
  • It is reverse of TMJ
• Examples: Hanau H series

Question 2. Discuss in detail about anterior teeth selection for edentulous patients. Add a note dentogenic concept.
Answer:

Anterior Teeth Selection:

Size: Methods:

• Pre-extraction records:
  • Diagnostic cast- prepared before extraction of teeth
  • Photographs- showing frontal & lateral view
  • Radiographs-Accurate measurements not obtained
  • Close relatives- If other methods fail
  • Extracted teeth- Best method
•  Anthropological measurements:
  • Cephalic index: Total width of upper anteriors= Bizygomatic width/3.36
  • Total width of lower anterior: 4/5 the width of upper anterior By H. Pound

• • By Sears: Width of upper central incisor Circumference of head/13

Anatomical Landmarks:

1. Size of maxillary arch:

• Distance between incisive papilla & hamular notch on one side.
• Distance between two hamular notch.
• Total width of all anterior & posteriors

• Canine eminence: Distance between two canine eminence combined width of anterior teeth

2. Buccal frenal attachments: Distance between two frena= total widths of maxillary anterior

 

3. Corners of the mouth: Distance between them = total width of anterior

4. Theoretical concepts:

• Winkler’s concept:
  • Physiological: Evaluate perioral tissues & arrange the teeth
  • Psychological: Camper’s line is used for it
    1. Raised in happy people
    2. Depressed downward in depressed people
  • Biomechanical: Placement of teeth in neutral zone
    
• Typal form theory (Leon Williams): Shape of teeth inverse the shape of the face

• Temperamental theory:
  • People based on mental, functional & physical characteristics contain teeth
• Concept of harmony:
  • Size of teeth corresponds to size of head

5. Others:

• Size of face
• Interarch distance
• Lip length

6. Color:

• Age
• Young people-lighter teeth
• Old people – dark teeth
• More shiny
• Brownish tinge
• Habits – smokers porcelain teeth
• Complexion- teeth selected in harmony with the complexion
• Colour of eyes color of iris is considered

7. Form:

• Patient’s face (Leon William’s concept)
• Facial form can be ovoid, tapering or square Teeth are selected according to it
• Example: Oviod teeth for oval face
  1. (a) Square
  2. (b) Oval
  3. (c) Tapering
  4. (d) combination

• Patient’s profile
• It can be convex, concave, or straight
• Labial form of anterior are selected according to it
• Example: Straight labial form for straight profile

8. Dentogenic concept (SPA concept):

• Sex:
  • Females: Rounded incisal edges
    1. Less angular teeth
    2. Incisal edges follow plane the curve of lower lip
    3. Rotated distal surfaces of central
    4. A visible mesial third of canines
    5. Exposure of more interiors while smiling
  • Males: More angular teeth
    1. Incisal edges are above the plane of occlusion
    2. Mesial end of laterals are hidden by centrals
    3. Middle 2/3rd of canine are visible
    4. Prominent cervical regions

• Personality:
  • Squarish-vigorous people
  • Flat: Executives

• Age:
  • Increased horizontal overlapping of posteriors
  • Reduced inter arch distance
  • Reproduce abrasion, and gingival recession in teeth as present in old individual

Question 3.Given Its functions and requirements of an articulator.
Or
Requirements of articulator
Answer:

Functions of articulator :

• Holds maxillary and mandibular casts in a determined fixed relationship
• Stimulates jaw movements like opening and closing
• Produces border and intraborder movements of the teeth similar to those in the mouth

Requirements of articulator : Requirements of articulator

1. Minimal requirements:
   • It should hold casts in the correct horizontal relationship
   • It should hold casts in the correct vertical relationship
   • The casts should be easily removable and reattachable
   • It should provide positive anterior vertical stop
   • It should accept face bow transfer record using an anterior reference point
   • It should open and close in a hinge movement
   • It should be made of non-corrosive and rigid materials that resist wear and tear
   • It should not be bulky or heavy
   • There should be adequate space present between upper and lower members
   • The moving parts should move freely without any friction
   • The non moving parts should be of a rigid construction
2. Additional requirements:
   1. Condylar guides should allow protursive and lat- eral jaw motion
   2. The condylar guide should be adjustable in a horizontal direction
   3. The articulator should be adjustable to accept and alter
   4. Bennett movement
   5. The incisal guide table should be customized

Question 4. Selection of posterior teeth in complete denture
Or
Criteria For Posterior Teeth Selection
Or
Posterior Teeth Selection
Answer:

Posterior teeth Size:

• Buccolingual Width: Such that it
• Provide escape of food
• Neutralizes forces from cheeks
• Prevent cheek biting

• Mesiodistal length: Such that
• The combined length of all posteriors doesn’t exceed the distance between canine & retromolar pad

• Occlusogingival height
• The occlusal plane should be at the midpoint of the interocclusal distance

2. Form:

• High cuspal height for steep condylar guidance
• Shallow cusps for shallow ridge
• Monoplane teeth for posterior crossbite