Ziad Al-Ani - Practical Procedures in Dental Occlusion

This has been an ongoing debate over many years with discussions on which lateral‐based occlusal scheme is the best for the patient. This chapter will discuss the rationale behind both and how to achieve them clinically.

This clinical scenario will highlight the flowing points:

checking the guidance prior to commencing treatment

conforming to the guidance by selecting a treatment plan which avoids changing it.

This chapter will discuss the significant concepts which need to be understood and planned when considering restoration of a tooth involved in the centric relation/retruded contact position. How to manage when the space is suddenly lost during crown preparation on a tooth that is the last in the arch.

Management of tooth surface loss is a complex treatment but some straightforward rules will help in diagnosis of the cause, monitoring of the situation and its management.

This chapter will illustrate the principles of management of non‐carious tooth surface loss (TSL) cases and will focus on:

achieving an appropriate OVD (when and how)

review of mounted study casts

diagnostic wax‐up

Dahl concept.

In this chapter, a patient has presented with a restored mouth with multiple crowns and they feel the teeth do not meet like before. They cannot find a comfortable position. The use of material that allows testing the increase of OVD when managing advanced restorative care cases will be discussed. A full description of clinical procedure will be offered here.

The following points are discussed in this chapter:

OVD increase

improving incisal and occlusal relationships

rule of thirds

aesthetic and functional analysis.

Dental implants may be more prone to occlusal overloading. A primary cause of peri‐implantitis and bone loss around implants is the excessive force applied from unwanted occlusal contact. The occlusal prescription of an implant‐supported restoration, therefore, has to be much more carefully designed than that on a natural tooth. The 10 principles of occlusion over implants are discussed in this chapter.

This is more of a dictionary of terms than merely a glossary of terms used in this book. This chapter isolates the relevant terms from the glossary of prosthodontic terms. published regularly in the Journal of Prosthetic Dentistry.

This chapter includes short answer questions for the reader to practise. The knowledge gained from reading this book will enable the reader to answer these questions effectively.

It is important we address terminology right at the start to reduce the confusion that has been created throughout the history of occlusion. As a source, we will use the Glossary of Prosthodontic Terms (GTP) (2017) edition for the most part.

The three most important terms are defined below.

Centric occlusion ( CO )– the occlusion of opposing teeth when the mandible is in centric relation (CR); this may or may not coincide with the maximal intercuspal position (MICP) (GTP 2017). Throughout the literature (Jiménez‐Silva et al. 2017, McNamara et al. 1995, Shildkraut et al. 1994, Weffort and de Fantini 2010), centric occlusion is also known as intercuspal or MICP and hence the confusion because the same term can indicate two different positions. So, to prevent further confusion, we will state that centric occlusion is MICP.

Centric relation– this position has five main points:

1 a maxillomandibular relationship, independent of tooth contact

2 the condyles articulate in the anterior–superior position against the posterior slopes of the articular eminences

3 the mandible is restricted to a purely rotary movement

4 from this unstrained, physiological, maxillomandibular relationship, the patient can make vertical, lateral, or protrusive movements

5 it is a clinically useful, repeatable reference position.

Each statement can be debated and to achieve consensus may be difficult, but the key point is that this is a tooth‐independent position, i.e. it can be recorded in edentulous patients. We feel that first statement is incomplete, and would add: a maxillomandibular relationship, independent of tooth contact at the correct occlusal vertical dimension (OVD) for that individual.

Centric relation contact position ( CRCP )– the occlusion of opposing teeth when the mandible is in centric relation; this may or may not coincide with the MICP (GTP 2017). This may involve one pair of teeth or several pairs or may coincide with all the teeth meeting. When the teeth touch then they slide from that position into MICP. According to Posselt (1952), 90% of the population have a discrepancy between both positions.

Other important terms are given in the table below and will be defined throughout the book and in the Glossary.

1 (2017). The Glossary of Prosthodontic Terms: ninth edition. J. Prosthet. Dent. 117: e1–e105.

2 Jiménez‐Silva, A., Tobar‐Reyes, J., Vivanco‐Coke, S. et al. (2017). Centric relation–intercuspal position discrepancy and its relationship with temporomandibular disorders. A systematic review. Acta Odontol. Scand. 75 (7): 463–474.

3 McNamara, J.A., Seligman, D.A., and Okeson, J.P. (1995). Occlusion, orthodontic treatment, and temporomandibular disorders: a review. J. Orofac. Pain 9: 73–90.