A Pattern of Centric Occlusion

Abstract

I deal occlusion might be defined as the state of occlusion in which the m axi­ mum number of teeth make contact simultaneously in centric relation, and in such manner as to enable the contacting planes to remain in occlusion over the widest possible range in the various ex­ cursive movements of the mandible. There is a great deal of latitude in N a­ ture’s tolerance in the approach to this ideal state, so that at times dentists see mouths in which the periodontal condi­ tion is much better or much worse than would be expected from a consideration of the state of occlusion. However, these are the exceptions rather than the rule. In attempting to correct faulty occlu­ sion it is well to bear in mind the ob­ jectives and decide how nearly the ideal can be approached and what compromise may be allowed, so that the resistance of the periodontium will be equal to the stresses. The purpose is threefold: first, to establish the best possible masticatory apparatus for the general welfare of the patient ; second, to achieve a balance suf­ ficiently good to protect and stimulate the periodontium, and third, to improve the appearance of the mouth, if possible. Before any reshaping is done, a com­ plete examination should be made, in­ cluding full mouth roentgenograms, in order to determine the condition of the periodontal tissues, the length and shape of the roots and the quality of the bone structure. Naturally, the weaker the sup­ port the more nearly perfect should be the occlusion to minimize the strain on the tissues. The first phase of the clinical exam­ ination, after consideration of the sup­ porting structures, is a careful study of the occlusion in centric relation. First, the patient should be asked to tap the teeth together rapidly, while the dentist applies light pressure against the chin and listens to the sound. If it is sharp and clean, centric occlusion is probably reasonably good, or the patient has found a relation which is unusually good in function. A muffled or chattering sound is an indication of premature contact of some of the cusps. To test further, the patient is asked to close his jaws and then attempt to retrude the mandible, with teeth touching. If this can be accomplished there will be a marked opening of the jaws, a defi­ nite indication that the original closure was an acquired rather than a true cen­ tric relation. Another and very reliable method of checking centric relation is to take a wax bite of the posterior teeth only, with the mandible retruded. Then the anterior relation can be checked visually during and after treatment, by comparing it with the relation in the original closure. The patient is instructed to close the jaws until the first teeth make contact, and then stop. The wax bite can be checked by holding it to the light. The premature contacts, or, rather, the first contact, will show as the thinnest. If the wax has been bitten through, it is best to take another wax bite, for it is probable that too much pressure was exerted, allowing the man­ dible to come forward and engage cusps other than those that are in contact in centric relation. This bite can be used