Laboratory Procedures Prior To Try In Long Essays

Laboratory Procedures Before Trying Long Essays

Question 1. Define articulator. Give classification, uses, and 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”.

Laboratory Procedures Before Wax Try-In

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

Articulator Uses:

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

Complete Denture Wax Try-In Preparation

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 articulator is open or closed
• Examples: Whip mix articulator:

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

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

Anterior Teeth Selection:

Size: Methods:

• Pre-Extraction Records:
  • Diagnostic cast- prepared before the extraction of teeth
  • Photographs- showing frontal and lateral views
  • 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
  • The total width of the lower anterior: 4/5 of the width of the upper anterior. By H. Pound

Record Base and Wax Rims in Complete Dentures

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

Anatomical Landmarks:

1. Size Of Maxillary Arch:

• Distance between the incisive papilla and the hamular notch on one side.
• Distance between the two hamuli notches.
• Total width of all anterior and posterior

• Canine Eminence: Distance between two canine eminences combined width ofthe  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 the perioral tissues and arrange the teeth
  • Psychological: Camper’s line is used for it
    1. Raised by happy people
    2. Depressed downward in depressed people
  • Biomechanical: Placement of teeth in the neutral zone
    
• Typal Form Theory (Leon Williams): The shape of teeth inverse the shape of the face

• Temperamental Theory:
  • People based on mental, functional, and physical characteristics contain teeth
• Concept Of Harmony:
  • The size of the  teeth corresponds to the size of the head

5. Others:

• Size of face
• Interarch distance
• Lip length

6. Color:

• Age
• Young people have lighter teeth
• Old people – dark teeth
• More shiny
• Brownish tinge
• Habits – smokers’ porcelain teeth
• Complexion- teeth selected in harmony with the complexion
• The colour of the 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
• Form Example: Oval teeth for oval face
  1. (a) Square
  2. (b) Oval
  3. (c) Tapering
  4. (d) combination

Custom Tray Fabrication in Complete Dentures

• Patient’s profile
• It can be convex, concave, or straight
• The labial form of the anterior is 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 the plane of the curve of the lower lip
    3. Rotated distal surfaces of central
    4. The visible mesial third of canines
    5. Exposure to more interiors while smiling
  • Males: More angular teeth
    1. Incisal edges are above the plane of occlusion
    2. The mesial end of the laterals is hidden by the central
    3. The middle 2/3rd of the canine is visible
    4. Prominent cervical regions

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

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

Question 3.Given its functions and requirements of an articulator.
Or
Requirements of the 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:
   • The articulator should hold casts in the correct horizontal relationship
   • The articulatorshould hold casts in the correct vertical relationship
   • The casts should be easily removable and re-attachable
   • The articulator should provide a positive anterior vertical stop
   • The articulator should accept the face bow transfer record using an anterior reference point
   • Articulator should open and close in a hinge movement
   • Articulator should be made of non-corrosive and rigid materials that resist wear and tear
   • Articulator 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 nonmoving parts should be of a rigid construction
2. Additional Requirements:
   1. Condylar guides should allow protrusive and lateral 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 and retromolar pad

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

Steps Before Wax Try-In in Prosthodontics

2. Form:

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