18 Journal dentaire du Québec Volume 41 Janvier 2004

Materials Used for Bite Registration inC.R. and M.I.P.

Prosthodontics

The dental chronicle of the Association of Prosthodontists of Quebec

Dr. Jean Patrick Arcache

The maximum intercuspation position (M.I.P.) isdefined as the occlusal position in which the teethpresent with the maximum number of inter-jawcontacts. Centric relation (C.R.) is obtained when thecondyles rest on the middle portion of the disc in themost antero-superior position of the articulareminence. This position is independent of dentalcontacts and it serves as a reference in differentclinical situations1.

Many materials exist which may register theinterocclusal relationship in C.R. or in M.I.P. In orderto faithfully reproduce the occlusal surface, thematerial must be viscous upon insertion and rigidonce it is set2,3. The M.I.P. registration is unnecessaryif a sufficient number of teeth are present to assurethe stability of the models in occlusion. Manystudies2,4,5 have demonstrated that the presence of abite registration gave rise to errors in mounting.However, it is important to use a registration materialin C.R. or when M.I.P. is unstable.

A material used for a bite registration must possessthe following properties:

• Precision• Dimensional stability• Resistance to occlusal forces• Ease of use• Cost

Materials most commonly used are:

1. Waxes2. Elastomers3. Zinc oxide based pastes

1. Waxes

The advantages of waxes are that they areinexpensive and easy to use. Their resistance toclosure is 7 N6. However, base plate waxes are notdimensionally stable and create serious mountingerrors in the vertical and horizontal dimensions 2,4,6,7,8.The more rigid waxes (Beauty pink, Moyco) whichfracture at room temperature, may however be usedas long as certain technical parameters are respected.

a. Soften the wax to 52 degrees Celsius,b. Record the cusp tips only,c. Cool in mouth with air spray and wait for

complete cooling instead of submerging inwater7,

d. Mount on an articulator as quickly as possible7,e. Eliminate tissue rests4 (fig.1)

2. Elastomers (polyethers and polysiloxanes)

Despite these materials being recommended forrecording M.I.P.9,10, they possess an elasticity that mayinduce a variation in mounting, especially in thevertical dimension. A constant occlusal pressureduring setting time (approximately 30 seconds) isobligatory. Excess material is removed with a scalpelblade prior to mounting. Finally, the operator mustexert pressure on the models while mounting on anarticulator to avoid rebound of the teeth in the biteregistration (fig. 2). This type of material is moreeasily used when mounting wax rims in completeand partial dentures.

3. Zinc oxide pastes (With or without eugenol)

These pastes are reliable for recording M.I.P.11. Theyhave a weak resistance to closing forces5. However,they are crumbly, harden quickly and stick to theteeth12. They require support due their fragility (fig. 3).

19 Journal dentaire du Québec Volume 41 Janvier 2004

Prosthodontics

1. The Glossary of Prosthodontic Terms, 6th edition 1994.2. Urstein M, et al… Clinical evaluation of materials used in registering jaw relationships. J.P.D 65: 372-7, 1991.3. Tripodakis AP. Evaluation of the accuracy of interocclusal records in relation to two recording techniques. J.P.D (1997) 77: 141-6.4. Feugeureux G, Abergel I. Comparaison de trois techniques d’enregistrement de l’occlusion centrée en prothèse conjointe. Les cahiers de

prothèse. N° 39 71-79, 19825. Strohover R. A comparison of articular mountings made with centric relation and myocentric position records. J.P.D 28: 379-390, 1972.6. Lassila V. Comparison of five interocclusal recording materials. J.P.D (1986) 55: 215-8.7. Millstein P et al… Determination of the accuracy of wax. interocclusal registrations Part II. J.P.D 51: 152-157, 1984.8. Lavigne J, et al… Usefulness of 3 interocclusal registration materials. Schweiz Monasschr Zahrkeild. 87: 1-9, 1977.9. Campos AA; Nathanson D. Compressibility of two polyvinyl siloxane interocclusal record materials. J.P.D (1999) 82: 456-61.10. Ockert- Eriksson G et al… Materials of interocclusal records and their ability to reproduce a 3 dimensional jaw relationship. Int. J. Prosth.

(2000) 13 :152-8.11. Balthazar-Hart, y et al… Accuracy and dimensional stability of four interocclusal recording materials. J.P.D 45: 586-591, 1981.12. Fattore L et al… Clinical evaluation of the accuracy of interocclusal recording materials. J.P.D 51:152-157, 1984.13. Pagnano V. A clinical evaluation of materials for interocclusal. registration in centric relation. Braz. Dent J (2000) 11: 41-47.14. Utz KH. Accuracy of check-bite registration and centric condyles position. J.O.R (2002) 29: 458-66.

We can combine different materials to record a biteregistration in C.R.: rigid wax (Beauty Pink, Moyco) oran acrylic resin (Pattern resin, G.C.) which acts as asupport to an elastomer or a zinc oxide paste. Thecombination of acrylic resin/zinc oxide paste wouldbe the most accurate13. A study reports that allregistration techniques lead to errors in transferring toan articulator and despite clinical procedures andmeticulous techniques, small occlusal adjustmentsare inevitable14.

Figure 2

Figure 3

Figure 1