Occlusion 2 Flashcards
What are three signs of occlusal overload to look for when examining occlusion?
Obvious facets, vertical enamel fractures, and abfraction
What two signs indicate occlusal instability?
Drifting and mobility not explained by periodontal disease
Name all the aspects to examine when assessing static occlusion.
Incisor relationship
Molar relationship
Overjet/overbite
Cross bites
Open bites
Individual tooth contacts
RCP-ICP slide
Define ICP and explain why it’s only stable under certain conditions.
Intercuspal Position is when teeth fit in maximum intercuspation; only stable if enough teeth are present to define it
When should occlusal contacts be marked in clinical practice?
Before: preparing a tooth or removing a restoration; After: placement of a crown or restoration
What are “tripodised contacts” in occlusion?
Contact points where opposing cusps meet, showing ICP stops
Distinguish between functional and non-functional cusps.
Functional: lingual cusps of upper posteriors and buccal cusps of lower posteriors that occlude in ICP
Non-functional: buccal cusps of upper posteriors and lingual cusps of lower posteriors that don’t occlude in ICP
What is the specific occlusal relationship between cusps and fossae in ICP?
Functional cusp of a tooth contacts the fossa of the opposing tooth
What is the definition of overbite, and how does it differ in Class II vs Class III?
Vertical overlap of incisors
Class II: deep overbite with mandibular anteriors contacting gingival third of maxillary lingual surfaces
Class III: edge-to-edge relationship or anterior open bite
What is overjet and how does it present in different malocclusions?
Horizontal relationship between upper and lower teeth; varies with maxillary/mandibular growth patterns
Define crossbite and name its two main types.
Condition where teeth are abnormally positioned buccally/lingually relative to opposing teeth; types: anterior and posterior
Distinguish between anterior and posterior open bite.
Anterior: lack of vertical overlap of anterior teeth when posteriors in full occlusion
Posterior: failure of contact between posterior teeth in full occlusion
What are the two main types of anterior guidance that rely on teeth?
Protrusion (incisal guidance) and lateral excursion (canine guidance or group function)
What happens during protrusive movement in terms of tooth contacts and condylar movement?
Condyles move forward and downward; only incisors ±canines touch; no posterior contacts
Define canine guidance and explain why it creates a “mutually protected occlusion.”
During lateral movement, only canines contact with no posterior contacts; protects posterior teeth from lateral forces
What are the four characteristics of a “mutually protected occlusion” (gold standard)?
Canine guidance, posterior disclusion in lateral excursions, no non-working/working side contacts, no protrusive interferences
What is group function and when is it commonly observed?
Multiple teeth in contact on working side during lateral movement; frequently seen in toothwear
List four principles for guidance and restored teeth.
Check guidance before restoring
Avoid vulnerable teeth providing guidance alone
Don’t change satisfactory guidance, Ensure sufficient space during preparation
What are the potential consequences of occlusal interference for a restoration?
Debonding
Crown fracture
Root fracture
What are the three main types of occlusal interference?
Working side, non-working side, and protrusive
Define working side contact and describe which cusps interact.
Contacts on same side as mandibular movement; similar cusps contact
Define non-working side contact and describe which cusps interact.
Contacts on opposite side from mandibular movement; dissimilar cusps contact
What constitutes a protrusive interference?
Any posterior contact during protrusion
Why should posterior contacts during excursive movements be avoided?
Teeth designed for forces along long axis not lateral forces; reduces muscle activity; prevents occlusal trauma and undesirable tooth movements
Define bruxism.
Parafunctional grinding of teeth; involuntary rhythmic/spasmodic gnashing, grinding or clenching not related to chewing
How does clenching differ from bruxism?
Pressing and clamping jaws and teeth together; often associated with acute nervous tension or physical effort
List five clinical signs and symptoms of bruxism.
Toothwear, fractured restorations, tooth migration, tooth mobility, muscle pain/fatigue, headache, TMJ pain/stiffness
What are the four main types of toothwear?
Abrasion, attrition, erosion, and abfraction
