Flashcards in Occlusion Deck (82):
What is occlusion?
How upper and lower teeth mechanically interact with each other: with jaw joints (TMJ), muscles, ligaments, and with periodontal tissues.
Why is occlusion important?
It is a threat connecting all disciplines in dentistry: restorative, orthodontics, periodontics, and more.
Occlusion is how we function.
Occlusion requires an understanding of ________ mechanical relationships.
Why do we use the articulator?
Simulates the jaw relations and create a standardized training enviroment for studying occlusal concepts.
What is the ultimate goal for every patient?
Maintainable health and freedom from disease for the total masticatory system.
What does "healthy total masticatory system" entail? (6)
1. Maintaining a healthy periodontium
2. Stable TMJ
3. Stable occlusion
4. Healthy teeth
5. Comfortable function
6. Optimum esthetics.
True or False
When examining a patient, a dentist should look only at the teeth.
Objective is harmony between the occlusion, TMJ, and muscles of mastication.
What are some common dental complaints?
Sore teeth and gums, tooth wear, loose or missing teeth, TMJ disorders, facial pain, and esthetics.
What is the main objective of the design of the masticatory system?
Masticating and swallowing of food
What 3 components contribute to the harmony of the masticatory system?
1. Stable TMJ
2. Anterior teeth in harmony with the envelope of function, ups, tongue and occlusal plane
3. Posterior teeth occluding with no interferences.
What 6 parts make up the anatomy of the TMJ?
1. Posterior slope of the eminence
4. Superior lateral pterygoid muscle
5. Inferior lateral pterygoid muscle
6. Posterior ligament
What are the two types of muscles and which one is stronger?
Elevators and Depressor.
Elevators stronger bc it is used to chew
What are the three elevator muscles?
1. Masseter: allows you to clench
2. Temporalis: Lifts mandible to close mouth. Mastication.
3. Lateral pterygoid muscle: Moves jaw forward and backward.
What is the posterior controlling factor/condylar guidance?
TMJs (slope of eminence)
What is the anterior controlling factors/anterior guidance?
Anterior teeth (overlapping of the teeth)
What is the controlling factor for the posterior teeth?
Both TMJ and Anterior teeth
What is the curve of spee?
Antero-posterior curvature of the mandible's occlusal alignment of the teeth, beginning at tip of lower canine, following the buccal cusps of mandibular posterior teeth and thru condyles.
Way teeth are aligned: from front to back, goes upwards.
What is compensatory curve of spee?
Maxillary teeth that corresponds to the curve of spee
Wat is the curve of wilson?
Buccal-Lingual curvature/Frontal alignment
Mediolateral curve that contacts the buccal and lingual cusp tip of each side of the arch.
The curve of wilson demonstrates the ______ inclination of lower posterior teeth, thus _____ cusp is higher than _____cusp on mandible.
Buccal cusp is higher than lingual cusp.
The curve of wilson demonstrates the ______ inclination of the upper posterior teeth, thus ______ cusp is higher than _____ cusp on maxillary.
Buccal cusp is higher than lingual cusp.
The curve of wilson affects what daily routine?
What is the curve of sphere of monson?
Ideal curve of occlusion in which each cusp and incisal edge touches the surface of imaginary 8 inches in diameter.
What is rest position?
When not chewing, speaking or swallowing, mandible is in clinical or postural (rest) position.
Open 1-3 mm
Why is it termed "rest" position?
Believed that the muscles were at equilibrium btwn gravity and natural elasticity of the muscles and soft ligaments.
What is the "rest rest" position?
~8mm open (electromyographic rest position)
True or False
Rest position is not consistent throughout different people
Can change even within same patient. Therefore, inaccurate to use rest position as reference to determine vertical dimension of face.
What is Freeway space/Interocclusal space?
The difference between vertical dimension of face when mandible is at rest and when teeth are in occlusion.
What three factors affect the freeway space?
1. Head and jaw position
What is Intercuspal Position (ICP)?
aka Max intercuspation, Habitual bite, Bite of Convenience. NOT Centric Occlusion
In occlusion, when jaw is closed and teeth fit together in MAXIMUM INTERCUSPATION.
*Independent of condylar position
What is Centric Relations (CR)?
Maxillomandibular relationship. Position when patient leans head back, independent of teeth.
What is retruded contact position?
Contact of a tooth or teeth along the retruded path of closure. Initial contact of a tooth or teeth on path from CR to ICP.
True or False
Some people RCP=ICP
True 10% of population
In normal occlusion, how do the teeth come together?
The maxillary teeth occlude about half a cusp distal to the mandibular teeth.
When does occlusal contacts occur?
When the centric cusps contact the opposing CF line. Viewed from the facial, these cusps typically contact in one of two areas: (1) CF areas and (2) marginal ridge and embrasure areas.
What is the most repeatable position?
In healthy teeth, ICP most repeatable.
In centric relation, where are the condyles seated?
Most anterior-superior positions, on thinnest avascular portion of the disk
In proper occlusion, Some working cusps occlude into ________ and some occlude with _______?
fossae; opposing marginal ridges.
Cusp-marginal ridge or Tooth-
Explain the cusp-marginal ridge or tooth-to-two-teeth occlusal relationship
Some centric cusps occlude in the embrasures between opposing teeth. (tooth-to-two-teeth occlusion) Others occlude in an embrasure area and contact only one opposing marginal ridge (cusp-marginal ridge occlusion).
What are the three types of occlusional contacts?
1. Cusp tip to fossa - 2 areas of contact (what we aim for
2. Tripod- 3 areas of contact. Pretty bad
3. Surface contact- whole thing touches. VERY BAD
What is projection pts. vs contact pts?
Where teeth actually hit.
Actual contact points may look like tripodism, usually not a perfect fit cusp to fossa so one contact may be seen as 3 dots
In normal occlusion, which cusps on the maxillary and the mandibular stop the jaw closure?
Mandibular: Buccal cusps of molars and pre-molars
Maxillary: Lingual cusps of molars and pre-molars
*Centric cusps stop jaw closure
What is the the mandibular lingual cusps of the molars and premolars called?
Non-centric cusps/Shear cusps
What is the maxillary buccal cusps of the molars and premolars called?
Non-centric cusps/Shear cusps
What are the functions of centric cusps?
Stop jaw closure and bears most of the force when biting.
Control direction of the axial forces on teeth.
Teeth are designed to absorb heavy forces in which direction and not in which direction?
Heavy forces in the direction of the long axis "axial force," but not forces in lateral direction.
What is the condylar movement from CR to RCP and vice versa?
What is the condylar movement from mandibular opening to max mandibular opening?
Translation/TMJ glide and Rotation
What is an impression?
Negative likeness or copy in reverse of the surface of an object
What is a preliminary impression
Made for the purpose of diagnosis, treatment, planning or fabrication of a tray
What is a diagnostic cast?
Life-size reproduction of a part or parts of the oral cavity and/or facial structures for purpose of study and treatment planning.
What are desirable characteristics of impression materials?
1. Biocompatible and non-irritating
3. Meet clinical requirements (setting time)
4. Adequate tear strength to allow for removal from mouth wo breaking
5. Elastic properties wo permanent deformation
6. dimenstionally stable
fow and wet ability
7. Adequate shelf life
8. Disinfected wo loss of accuracy.
9. Compatible with cast and die materials
10. Min equipment required for use
What are the phases of when alginate turns from liquid to gel?
Sol to gel phase (irreversible)
What are the advantages of alginate?
1. Easy to manipulate
2. Comfortable for pt
3. Relatively inexpensive
4. No equipment necessary
5. Chemical set
What are the disadvantages of alginate
1. Not as accurate
2. Low tear strength
3. Poor reproduction of surface detail
4. Must be poured immediately
5. Can be poured only once
When are alginates used?
For diagnostic purposes
What is the chemical rxn of alginate?
Potassium alginate + Calcium sulfate + H2O --> Calcium alginate gel + Potassium sulfate
What is the shelf life of alginates?
Deteriorates rapidly at elevated temp. Stock no more than year supply. Store in cool and dry place.
What is the diff in gelation time between type I (fast setting) and type II (regular set)?
Type I: Gels in 60-120 secs Working time: 30-75 secs
Type II: Gels in 2-4.5 mins Working time: 2-3.5 mins
What is the max time to wait before pouring cast?
How much space should there be btwn tray and teeth/gingiva?
How long should you mix microstone in the vacu mix for?
What is an articulator and what is it mainly used for (3)?
Device which casts are attached to that allow simulation of jaw position and movement.
1. Supplement occlusal examination
2. Treatment planning/trial occlusal adjustment/ diagnostic wax
3. Help the lab create restorations
In an articulator, what is the horizontal axis of rotation?
Variability of the position of the horizontal axis of rotation in relationship to the maxillary dental cast.
What is the condylar inclination/ fossa components of the articulator?
THE ANGLE AT WHICH THE CONDYLE DESCENDS ALONG THE ARTICULAR EMINENCE. Ability to simulate laterotrusive movement.
What is the inter condylar distance of the articulator?
Adjustability of the distance btwn the vertical axes of rotation.
What is the Bennett angle?
Adjustability of the angle and capability of simulating side shift movement.
What is the incisal guidance?
Adjustability and ability to simulate the anterior guidance of the natural dentition.
What are the 4 classes of articulators?
1. Class I: Simple Hinge (Non-adjustable)
2. Class II: Arbitrary Value (Non-adjustable)
3. Class III: Semi-adjustable (adjustable)
4. Class IV: Fully Adjustable
What is the articular guidance set to on our articulators?
What are the limits of Class I articulators?
Limited to inaccurate hinge opening and closing. Maximum intercuspation position is the only position. Casts mounted wo facebow.
What is the Class II articulators capable of?
Capable of lateral movement. But fixed condylar inclination, vertical axes, and bennett angle.
What is the Class III articulators capable of?
Capable of lateral, protrusive, and Bennett movements to varying degrees. Can simulate curvilinear anatomical movements.
Describe 3 things about simple articulators.
1. No facebow
2. ICP mounting only
3. Limited jaw movements
What are the two types of Class III?
Arcon: Guidance of condylar movement in maxillary and centers of axial rotation in mandibular. (what we use)
Non-arcon: Guidance of condylar movement in mandibular and centers of axial rotation in maxillary.
When is class IV used?
Extensive restorative procedures, and TMJ dysfunction. It closely simulates path of natural dentition.
In which class is the inter-condylar distance adjustable and if not, at what width is it fixed at?
Class IV adjustable otherwise fixed at 110mm.
What is a face bow?
A device that transfer the specific relationship of maxillary teeth and TMJ of patient to the articulator.
What is the function of the face bow?
Record the relationship of the maxillary arch to the horizontal axis of rotation of the mandible (hinge axis).
What are the repercussions of using an articulator wo facebow registration?
Not able to simulate the paths of jaw movements or the angulation of the occlusal plane.
What are the 2 basic types of facebows?
1. Hinge axis transfer bow (kinematic)
2. Simple facebow (arbitrary or earpiece)