Reorganised occlusion



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Reorganising the Occlusion
Introduction
A “reorganised occlusion” is an occlusion in which the pattern of occlusal contacts is deliberately changed or reconstructed.1
What’s the point?
Reorganising the occlusion is done because the existing ICP is unsatisfactory for your restorations, or because there is a specific problem that can only be solved by reorganising the occlusion.1 This can be further explained using some examples.

Example 1: The complete denture (Figure 1)2
When you make a set of complete dentures you are effectively rebuilding the occlusion so that the teeth bite together without displacing the denture. Usually we reorganise the occlusion and use the jaw position determined by the TMJ as our starting point. This is of course Centric Relation.


Figure 1: edentulous – no teeth, therefore no occlusion.2



Example 2: Protecting and restoring a worn dentition (Figure 2) 3
Excessive wear leads to poor appearance, poor function, sensitivity and pulp damage. To relieve symptoms the teeth need to be covered or reconstructed with a restorative material. The extent of treatment depends whether wear is localised or generalised.
Localised anterior wear can be managed using a Dahl approach (Figure 2). This aims to open the bite posteriorly allowing the posterior teeth to erupt into the new occlusion. The anterior teeth can then be restored utilising the space created.
Generalised wear, or when the posterior teeth require extracoronal restorations, requires a more extensive plan. Teeth need to covered or rebuilt so that the upper and lower teeth fit together again in a stable scheme that spreads the occlusal load predictably around the dental arches.1 This is what we think of classically as reorganising the occlusion.1


Figure 2: a,b) Pre-operative view of the worn anterior teeth. c) Immediate post-operative view in ICP following the placement of direct composite restorations 11, 21, 41 and 42 at an increased vertical dimension of occlusion. d) Re-establishment of occlusal contacts at 3 months.3
The Principles of Reorganising
Principle 1: Rebuild the new occlusion around a reproducible position
In situations where there are no teeth or the existing ICP is unsatisfactory, CR is normally used as the basis for constructing a new ICP.1 If you cannot manipulate your patient into CR, it is best not to embark on reorganising the occlusion.1
If the patient has a TMD, the general principle is to diagnose it first, and then treat it by conservative means before embarking on restorative work.1
Principle 2: Decide on the vertical dimension
At what position on the CR hinge axis will the occlusion be reorganised?
In complete dentures the rest position is used as a reference point. A freeway space of 2-3mm is usually used.
When teeth are present, there are no fixed rules, as the rest position readjusts to accommodate most reasonable increases in vertical dimension, as long as a stable occlusal scheme is provided.1 If you need to construct aesthetic restorations, the amount of space needed for your restorations will determine the new vertical dimension.1 A stabilisation splint may be prescribed to test any change in vertical dimension prior to placing any expensive restorations.
Principle 3: Create stability in ICP and avoid damage in excursions – You need an occlusal scheme!
Various occlusal schemes are described in the literature and are shown in Table 1 (see below). In summary, all schemes use CR as the starting point for construction, however they all differ in their choice of guidance teeth and the pattern of ICP contacts.
The small differences between schemes are probably not very important. The most important thing is to have a predetermined plan as to how your patient’s teeth will fit together and which teeth will provide guidance.

Table 1: Features of some of the best known occlusal schemes1


Occlusal Scheme

RCP-ICP relationship

Excursive Contacts

Comments

Pankey-Mann-Schuyler (1963)

Area of freedom between ICP and RCP (<0.5mm) and morphology functionally generated.

Anterior guidance determined functionally on temporaries.

Canine guidance or group function.



Considerable potential for error with functionally generated path technique - used to determine occlusal morphology of posterior teeth.

Gnathological (1964)

Coincident, with tripod contacts.

Canine Guidance. Posterior disclusion in all excursions.

Anterior and Posterior contacts are mutually protected. ψ



Good for cases without large horizontal RCP-ICP slide.

Fully adjustable articulator should be used.



Youdelis (1977)

Coincident, with tripod contacts.

Same as Gnathological, but designed to drop into group function if canines wear or move.

Useful where excursive parafunction cannot be controlled or where canine is compromised.

Area of freedom in centric ζ (1982)

Freedom between ICP and RCP (0.5mm ± 0.3mm).

Cusp to fossa occlusion.



Canine guided or group function. Anterior guidance will be delayed during posterior contact in area of freedom.

Useful where there has been a large horizontal component in the RCP-ICP slide prior to treatment.

Area of freedom needs careful adjustment.


ψ “Mutually protected” means that in ICP, the posterior teeth support maximum biting force while the anterior teeth are out of contact, but in excursions the anterior teeth provide guidance to disclude the posterior teeth and protect from lateral loading.1


ζ “Freedom in centric” occlusion occurs when the mandible is able to move anteriorly for a short distance in the same horizontal and sagittal plane while maintaining tooth contact.4
The new ICP
The ICP is usually quite stable, with the maxillary and mandibular teeth fitting together like a lock and key.1 When a new ICP is built, it needs to be stable too. Cusp and fossa need to fit together securely when the jaws are closed, otherwise teeth will drift and overerupt.
Occlusal surfaces will be stable provided that cusps and preferably fossae, rather than marginal ridges of opposing teeth, are aligned to direct loads down long axis rather than obliquely.1
The gnathological literature goes further, stating that the perfect cusp to fossa relationship will be a tripod contact, consisting of three discrete contacts around the cusp tip for perfect stability. This can be difficult to achieve and is often lost as restorations wear.1
It is the practitioner’s responsibility to select the appropriate materials to restore the occlusal surfaces recognising that some materials may cause excessive wear e.g. porcelain against tooth or metal therefore the sensible option is to adopt a like-against- like policy. Metal alloys are less damaging to tooth than porcelain.
Good practice and common sense with respect to guidance when restorations are being placed during a reorganisation1


  1. Canines are the optimum guidance teeth for lateral excursions, provided they are not compromised periodontally, structurally or restored with non-retentive restorations or post crowns.1 Under such circumstances, the guidance is best transferred to the premolars, or where possible creating group function between all of the teeth in the buccal segment.1

  2. When the canines alone are not going to be used for guidance in lateral excursions, shared guidance is advisable, but can be difficult to achieve.1

  3. Protrusive guidance is usually best shared between the two central incisors with equal contacts in the edge to edge position.1 Crowned lateral incisors are structurally compromised, so if possible make their guidance contacts light.1

  4. Where there are bridge pontics, in particular cantilevers, it is best to avoid any guidance on these.1

  5. To ensure that the patient is comfortable with their reorganised occlusion, the concepts of “mutually protected occlusion” and “freedom in centric” are helpful.1



Further Reading and References




  1. Wassell, R. Naru, A. Steele, J. Nohl, F. (2008) Applied Occlusion. Quintessence Publishing Co. Ltd. London.

  2. http://www.hammerdental.com/dentures1.htm.

  3. N J Poyser, R W J Porter, P F A Briggs, H S Chana & M G D Kelleher

British Dental Journal 198, 669 - 676 (2005) Published online: 11 June 2005

doi:10.1038/sj.bdj.4812371.



  1. Davies, S.J. and Gray, R.J.M. (2002) A Clinical Guide to Occlusion. British Dental Association. London.

  2. Howat, A.P. Capp, N.J. Barrett, N.V.J. (1991) A Colour Atlas of Occlusion and Malocclusion. Wolfe Publishing Ltd. London.

  3. Shillingburg, H.T. (1997) Fundamentals of Fixed Prosthodontics. Third Edition. Quintessence Publishing Co. USA.







Adam Jowett


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