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An Introduction to Occlusion

An Introduction to Occlusion. 23/11/09. A patient’s occlusion needs to be considered every time a restorative procedure is carried out For some patient’s an occlusal assessment will be need to be extensive and detailed, for other patients it may be relatively simple

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An Introduction to Occlusion

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  1. An Introduction to Occlusion 23/11/09

  2. A patient’s occlusion needs to be considered every time a restorative procedure is carried out • For some patient’s an occlusal assessment will be need to be extensive and detailed, for other patients it may be relatively simple • Which category does your patient fall into?

  3. Procedures and Princesses • Simple restorative treatment may only require a cursory occlusal examination, however other procedures such as: canine replacement / restoration, multiple crown / bridge work will require more detailed assessment and for indirect restorations-mounting of models on an articulator. • Some patients are particularly sensitive to occlusal change

  4. The Princess and the Pea • Some patients may be acutely aware of small occlusal discrepancies!

  5. ICP or RCP • With the exception of complete dentures most of the restorative work you will carry out as an undergraduate will be conformative i.e. you will be maintaining the existing occlusal relationships • To do this you will need to identify ICP and excursions from this position

  6. Intercuspal Position • Position when the teeth exhibit maximum intercuspation • “Normal biting position” • This is the position that the patient will habitually close into, where they feel comfortable

  7. Identifying ICP • Examination of occlusal positions and relations are generally better carried out with the patient seated rather than lying down, tilting the head backwards will tend to move the mandible distally.

  8. Identifying ICP • Ensure the patient is relaxed and ask them to gently close their teeth together. Some patients will tend to protrude in to an edge to edge contact • With patients who protrude it may help to guide them into RCP by curling their tongue to the back of the palate as they close and then letting them slide forward into ICP

  9. Once you have identified ICP… • Some patients exhibit lovely, even meshing of all their teeth. • Other patients don’t! • Identify a couple of pairs of teeth that contact and make a note of them (this will allow comparison with ICP post operatively)

  10. Excursions • Having identified ICP and noting contacts, we need to explore how the mandibular teeth relate to the maxillary teeth in “chewing movements” • There are complex methods of recording these movements but here we will consider just 3 movements:

  11. ICP Right Lateral Excursion Left Lateral Excursion Protrusion

  12. Protrusion • Starting from ICP ask the patient to slide their lower teeth forward whilst keeping them together. • Look to see if any posterior teeth are in contact during protrusion

  13. Lateral Excursions • Again, starting from ICP ask the patient to slide their lower jaw to the Left keeping the teeth in contact. Look to see if there are any teeth in contact on the right side • Patients only need to slide into an edge to edge position • Repeat for the Right side again looking to the opposite side to see if any teeth are in contact there.

  14. Lateral Excursions

  15. What are we looking for? • We are trying to identify which teeth are being subjected to lateral forces in chewing movements

  16. Why? • Teeth generally respond well to forces directed along their long axis • Teeth generally don’t respond well to lateral forces especially when they have been weakened by direct restorations and/or have been compromised periodontally.

  17. In an ideal world… • When the mandible makes excursive movements the vulnerable areas of the dentition would be protected from lateral forces by “protective tooth contacts”

  18. “Protective contacts???” • Imagine this model of protrusive movement where there are no protective contacts and all mesial slopes of the lower teeth and distal slopes of the upper teeth are in contact during the protrusive movement

  19. Video 1

  20. “Protective contacts???” • Now imagine a second model where the palatal surface of the anterior teeth and the incisal edge of the lower teeth serve to separate all the posterior teeth during the protrusive movement thus protecting vulnerable posterior cusps • This protection is Incisal Guidance

  21. Video 2

  22. Canine Guidance • Ideally, in lateral excursion contact between the canine teeth on the working (chewing) side would serve to separate all teeth on that side and there would be no contacts on the other (non-working) side. • Canine Guidance Working side Non-working side

  23. Group Function • In some patients multiple teeth contact on the working side. • This is termed Group Function • Deemed less ideal that canine function but at least possibly destructive, lateral forces are spread between several teeth

  24. Interferences • In some patients, potentially damaging contacts may occur between other teeth during excusions. These are termed Interferences Non-Working Side Interference

  25. Terms… • Canine guidance • Incisal guidance • Group function • Interferences • Working side • Non-working side

  26. Canine Guidance • In this occlusal scheme, the mandibular and maxillary canines are the protective contacts, are the only teeth in contact in lateral excursions and serve to separate all the other teeth. • Canines are generally ideally suited to this task, having robust roots

  27. Incisal Guidance • In this occlusal scheme, the incisal edges of the mandibular incisors and the palatal surface of the maxillary incisors serve to disclude all posterior teeth in protrusive excursions

  28. Group Function • In this scheme multiple teeth contact on the working side in lateral excursions

  29. Interferences • Non-ideal, potentially damaging contacts that occur during excursions

  30. Working Side (WS) • The side that the mandible moves towards in function

  31. Non-Working Side (NWS) • T’other side (surprisingly!)

  32. A Brief Occlusal Assessment • Establish ICP • Note contacts in ICP • Note contacts in protrusion ( incisal guidance?) • Note any posterior contacts during protrusion • Study contacts in LLE (left lateral excursion) on WS (canine guidance or group function). Note NWS interferences • Repeat for RLE

  33. Example of Occlusal AssessmentMrs. Jones • Incisal guidance 21/12 21/12 • LLE- Canine guidance NWSI x • RLE-Group function 654/ NWSI /5 654/ /5

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