FINAL EXAM - Occlusion Flashcards
What is occlusion?
The contact relationship between the max and mand teeth when the jaw is in a fully closed position AND the relationship between teeth of the same arch.
What 4 things determine occlusion?
1) Shedding of primary teeth
2) Associated facial muscles
3) Tongue function/posturing (tongue thrusting)
4) Orofacial habits/behaviors (thumb sucking)
What is “Ideal Occlusion”?
- 138 occlusal contact points between 32 teeth
- Rarely ideal
- “Centric Occlusion” as the standard for describing occlusion
What is Centric Occlusion?
- The habitual way we close/bite down
- The voluntary position of dentition that allows maximum contact when teeth occlude
- Each tooth of 1 arch occludes with 2 from the opposing arch (except mand central incisors and max 8’s)
What are the 3 areas of centric contact?
1) Height of cusps
2) Marginal ridges
3) Central fossae
What is Centric Relation?
- The most RETRUDED position of the mandible
- Usually 1 mm posterior to CO
- Ideally: CO = CR
What is another name for the “Rest” position?
Interocclusal Clearance or “Freeway Space”
What is the “Rest” position?
- The most relaxed position when muscles are at rest
- When jaws are not being used for speech, respiration or masticatory movements
- Teeth are usually 1 - 3 mm apart
What is “Malocclusion”?
- Lack of ideal occlusion when in CO
- Any deviation from ideal relation of max. teeth to mand. teeth and arches.
- Poor alignment within an arch (crowding, spacing, rotations, etc.)
- Poor alignment between arches (difference in size of arches)
What 5 things influence the development of occlusion and malocclusion?
1) Biological (inherited: tooth size, jaw size, growth patterns)
2) Environmental (habits, caries, trauma, latrogenic Tx)
3) Physiological (growth/eruption patterns)
4) Pathological (minor - missing teeth, major - cleft palate)
5) Developmental or systemic disease (neural, endocrine, vascular, muscular, etc.)
How are the arches divided?
3 segments:
1) Anterior (ends at labial ridge of canines)
2) Middle (distal of canines to MB cusp of 1st molar)
3) Posterior (buccal cusp of 1st molar to 2nd and 3rd molars)
- Canines and 1st molar act as anchor support for both arches *
What are the 5 phases of arch development?
1) 1st molar erupt - helps to support the jaw while the primary anteriors are shed
2) Incisors erupts (central, then lateral) - erupt lingual to primary roots
3) Premolars erupt - premolars are much smaller than molars they replace (creating the “Leeway Space”)
4) Canines and 2nd molars erupts - canines wedge themselves between laterals and 1st premolars WHILE 2nd molars erupt and support the 1st molars during wedging of canines.
5) 3rd molars erupt - usually jaw length is NOT sufficient for these
What is the “Leeway Space”?
The space created due to the difference in size (MD) between the primary molars and permanent premolars that replace them.
What are “Parafunctional Habits”?
Movements of the mandible that are NOT within the normal range of motion associated with speech, respiratory and masticatory movements
Give 5 examples of parafunctional habits.
1) Clenching
2) Bruxism/grinding
3) Thumb sucking
4) Tongue thrusting
5) Environmental habits (ie. eating sunflower seeds)
What is a “mesiognathic” facial profile?
Straight/flat
What is a “retrognathic” facial profile?
Retruded mandible (ie. buck teeth)
What is a “prognathic” facial profile?
Protruded mandible (ie. under bite)
Describe Class I Occlusion.
“Neutrocclusion”
- Mesognathic profile
- MB cusp of max 1st molar in buccal groove of mand 1st molar
- Max canine between mand canine and 1st premolar
Describe Class II Occlusion.
“Distocclusion”
- Retrognathic profile
- DB cusp of max 1st molar in buccal groove of mand 1st molar
- Mandibular teeth are distal to normal position by atleast the width of a premolar
- Prominent maxilla and retruded mandible
Describe Class II Division I Occlusion.
- Retrognathic profile
- Max. anterior teeth protrude facially from mandibular incisors
Describe Class II Division II Occlusion.
- Mesognathic profile
- Max. central incisors are upright or retruded
- Max. lateral incisors are tipped labially or overlap centrals.
Describe Class III Occlusion.
- Prognathic profile
- Mandibular teeth are anterior to normal position by atleast the width of a premolar
- Max. incisors are lingual to mand. (but can be edge to edge)
Anterior cross bite
- Max. incisors are lingual to mand. incisors
- Tissue impingement: teeth may contact lingual gingiva
Posterior cross bite
- Max. posterior teeth are lingual to their normal position
- Mand. posterior teeth are buccal to their normal position
Edge to Edge
- Incisal surfaces meet
End to End
- Molars/premolars occlude cusp to cusp when viewed MD
Open Bite
Lack of occlusal/incisal contact between maxillary and mandibular teeth
Overbite
The VERTICAL overlap of max. incisors over mand. incisors (%)
Normal Overbite
Overlap within the incisal 1/3
Moderate Overbite
Overlap within the middle 1/3
Severe Overbite
Overlap within the cervical 1/3
Overjet
The HORIZONTAL distance between the labioincisal surface of mand. incisors and the linguoincisal surface of max. incisors (mm)
Underjet
The HORIZONTAL distance betwen the labioincisal surface of max. incisors and the linguoincisal surface of mand. incisors
Labioversion
Tooth positioned labial/facial to its normal position
Linguoversion
Tooth positioned lingual to its normal position
Buccoversion
Tooth positioned buccal to its normal position
Supraversion
Tooth elongated ABOVE the line of occlusion
Infraversion
Tooth BELOW the line of occlusion
Torsoversion
Tooth that is turned or rotated
Midline Deviation
When the midline of the mand. is shifted to the left or right of the max. midline
Curve of Spee
The upward curve of the occlusal plane
Curve of Wilson
The curve of both arches when viewed from the posterior region
What is the vertical alignment of the maxillary posterior teeth?
- Crowns have a slight buccal inclination
- Roots have a slight lingual inclination
What is the vertical alignment of the mandibular posterior teeth?
- Crowns tip lingually
- Roots tip buccally
What is the vertical alignment of ALL the teeth?
- All teeth have a slight MESIAL tilt (EXCEPT max 8’s)
- Anterior teeth have a labial protrusion
Primary Occlusion
- Also has ideal form
- Canine relationship is same as permanent dentition
What is the “Terminal Plane?”
The ideal molar relationship in primary dentition when in centric occlusion (includes flush terminal plane and mesial step)
What is the “Flush Terminal Plane”?
The primary max. and mand. 2nd molars are in end to end relationship
What is the “Mesial Step”?
The primary mand. 2nd molar is MESIAL to the max. 2nd molar
What is the “Distal Step”?
The primary mand. 2nd molar is DISTAL to the max. 2nd molar
- NOT an ideal molar relationship
- NOT a type of terminal plane relationship
What are “Primate Spaces”?
- Natural occuring spaces that occur as a result of jaw growth
- Provide room for eruption of permanent teeth
- May occur between primary teeth
- Spaces noted between: max. lateral incisors and canine & mand. 1st molar and canine
Describe “Protrusion”
- When the mandible moves forward from CO or CR
- Mand. anterior and max. anteriors end in edge to edge relationship
- 8 anterior teeth should be touching and assume the stress of protrusive movements
(teeth in contact during protrusion are charted on odontogram)
Describe “Lateral excursion”
- Movement of the mandible from CO or CR to the left or right, until canines are cusp tip to cusp tip
Cuspid Rise
When ONLY the cuspids/canines are in contact during excursion (“ideal”)
Group Function
When the premolars or molars also contact anytime during the lateral excursion ON THE SAME SIDE
- Usually happens if there is attrition on the canines
How do you chart lateral excursion?
- If movement is to the right - RIGHT is the working side.
- LEFT is the non-working side
- If teeth on the non-working side occlude - they are an INTERFERENCE and are documented in RED
What is “Premature Contact”?
Occurs when 1 or 2 teeth contact before other teeth
What causes Premature Contact?
- Malalignment (supraversion, linguoversion, rotations, tipping, etc.)
- Latrogenic dentistry (restorations that are too high)
What can Premature Contacts cause…
- Abnormal stress on the TMJ
- Overusing muscles = tenderness
- Tooth pain, mobility or widening of PDL space
- Tooth may fracture
What is “Occlusal Trauma?”
When forces of occlusion exceed that of which the bone is capable of supporting
What are clinical signs and symptoms of Occlusal Trauma?
- Increased muscle activity/tenderness (may become habitual - cheek biting, grinding, etc.)
- Tooth mobility
- Attrition, abfraction, wear facets, fractures
- Senstitivity
- TMJ problems
What are histologic signs of Occlusal Trauma?
- Widening of PDL space
- Necrosis (cell death) of PDL
- Loss of lamina dura/thickened lamina dura
- Root resorption
- Cemental tears
- Furcation involvement
