occlusion symposium Flashcards
Why must occlusion avoid overloading? ⚠️
To prevent:
Fracture of a weakened cusp 🦷
Damage to the periodontal ligament 💥
Overloading can come from:
Parafunction (e.g. grinding) 😬
Premature contacts 🧱
Forces in wrong direction ⬅️➡️⬆️⬇️
What is occlusion? 🦷
Occlusion is how the upper and lower teeth meet.
👩⚕️ Orthodontist: Focuses on how the teeth and jaws are aligned.
🛠️ Restorative dentist: Focuses on the dynamic interaction of teeth and the forces during function.
What happens during normal jaw opening? 👄
Condyles move forward and downward
Muscles: Lateral pterygoid and digastric
Initial opening: rotation 🌀
Further opening: translation 🚶♂️
What is ICP? 📌
Intercuspal Position (ICP) = the most stable and tooth-guided position.
= Where teeth meet best. 🧩
= Used to evaluate restorations and occlusal health.
What is RCP? 🔙
Retruded Contact Position (RCP) is where the condyles are most superior and posterior in the glenoid fossa.
Not tooth-guided but ligament-guided.
There may be a slight slide from RCP to ICP. 🧊➡️📌
What is canine guidance? 🐶
Only the canine teeth contact during side movements, protecting posterior teeth from lateral forces.
✅ Efficient
✅ Reduces wear
✅ Strong root 💪
What is group function? 👨👩👦👦
When multiple posterior teeth contact on the working side during lateral movement.
Common as we age.
🟠 Less ideal than canine guidance
⚠️ Can stress weakened cusps
What is interference? 🚫
An unwanted contact between teeth during jaw movement, causing:
Pain 😣
Wear facets
Restoration failure ❌
What is incisal guidance? 👅
The anterior teeth (especially incisors) guide the jaw during protrusion.
Posterior teeth disclude
Reduces force on molars 🛡️
Dictates mandibular movement
What is an articulator used for? 🧰
To replicate a patient’s jaw movements using mounted models.
Used to:
🦷 Check occlusion
🛠️ Make crowns, bridges, dentures
🧪 Investigate changes (e.g. canine to group function)
What is a facebow? 🎧
A tool to measure the position of the upper teeth in relation to the hinge axis and glenoid fossa.
✅ Allows accurate mounting
✅ Records patient-specific anatomy
What’s the difference between ARCON and non-ARCON articulators? ⚖️
ARCON: Condyles attached to the lower member (like anatomy) ✅
Non-ARCON: Condyles attached to upper part, non-anatomical ❌
When is conformative vs reorganized occlusal treatment chosen? 🔄
Conformative: 🛠️ Keep existing occlusion if stable
Reorganised: 🔁 Change occlusion if:
Damaging bite
Restoring worn teeth
Need to increase OVD
Improve aesthetics
What is an interocclusal record? 📝
Material placed between teeth (e.g., blue mousse or wax) to capture the bite position for mounting models in:
ICP
RCP
Protrusion/lateral positions
What is fremitus? 📳
A vibration felt on a tooth during function, indicating lateral forces.
➡️ Test by placing a finger on the tooth and asking patient to tap
⚠️ If present, check occlusion/restorations
What are wear facets? 🔍
Shiny, flat surfaces on teeth or restorations caused by parafunctional habits (e.g. grinding).
💡 Must be recreated in restorations to avoid interference
What is the BULL rule? 🐂
Identifies cusps at risk in group function:
Buccal Upper
Lingual Lower
➡️ These take lateral load
⚠️ Protect with onlays or crowns if weakened
Why do crowns often feel high? 👑
Due to errors in:
Impression
Articulation
Occlusal reduction
Temporary loss
🔧 Adjust or remake the crown
How to fix a high crown? 🔧
If high in ICP ➡️ Adjust cusp height
If free in lateral but high in ICP ➡️ Deepen fossa
🪥 Always recheck bite and guidance
