Factors Affecting Support of Full Dentures

Thomson, John C (1967) Factors Affecting Support of Full Dentures. Doctor of Medicine and Surgery thesis, University of Glasgow.

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Since satisfactory retention and stability now permit the acceptance by full dentures of wider functions, the support of the load imposed upon the denture-bearing tissues assumes greater significance. A plea is made, therefore, for the recognition of support as an attribute equal in importance to retention and stability for the success of full dentures. The tissues which receive the load from the teeth of full dentures are less suited for that purpose than the tissues which support natural teeth. The reaction of the denture-bearing tissues may be unfavourable under ill-fitting dentures, and there may be clinical and histological signs of tissue deterioration in these circumstances. Subjective symptoms may accompany these adverse reactions, but in many instances the comfort of the patient may be unimpaired and normal function may be maintained. On the other hand, pain and discomfort leading to loss of function may occur in the absence of clinical signs . It would appear that individual variations in the load-bearing potential of the denture-bearing area, and the loads which are applied, are significant in this context. The loads recorded during tests of biting power are limited by the tolerance of the subject and his tooth-supporting structures. Full denture wearers exhibit much smaller biting forces than subjects with natural teeth. Masticatory function demands much less than the maximum exertion of which the muscles of the jaws are capable, but the recording of loading of the tissues during normal masticatory function, and especially to take account of loading during habitual non-functional occlusion of the teeth, presents technical difficulties. Since the distribution of the load over the denture-bearing areas is not uniform, the pressure upon any given area cannot be deduced, but deviations from normal in the total loading imposed and in the area available for load-bearing will be reflected in the support which the tissues are required to provide. A distinct pattern of attrition caused by persistent tooth-grinding and tooth-clenching habits was identified during examination of patients wearing acrylic full dentures and was frequently associated with pain and discomfort in the denture-bearing tissues. Attrition of acrylic teeth was simulated under laboratory conditions, and it required the prolonged and vigorous application of loads, equivalent to those reported to be used during mastication, to produce attrition similar to that observed clinically. Hence attrition due to habits of clenching and grinding of the teeth is indicative of considerable extra loading having been imposed upon the denture-bearing tissues. In a consideration of diagnosis, support failure is distinguished from other causes of denture discomfort. Especial note is made of cases in which discomfort leading to intolerance of dentures was not accompanied by any clinical signs in the tissues or by any change in the usual histological appearance of denture-bearing mucosa. These cases were caused by over-loading, due either to excessive vertical dimension of the occlusion or to persistent non-functional tooth-occluding habits. The diagnosis of these two precipitating causes is discussed. In considering the treatment of failure of support of full dentures, preventive measures to promote conservation of alveolar bone and the maintenance of favourable residual alveolar ridges and healthy mucosa are advocated. Suitable prosthetic technique and the treatment of the defective denture foundation is considered . Methods of reducing the effect of the load on the tissues aim to distribute the load widely and evenly. Reduction of the total load when it is found to be excessive is a possible expedient, and the elimination of non-functional habits of occlusion is discussed. In these ways an acceptable balance may be achieved between the load which the dentures impose and the support which the tissues can comfortably provide.

Item Type: Thesis (Doctor of Medicine and Surgery)
Qualification Level: Doctoral
Keywords: Dentistry
Date of Award: 1967
Depositing User: Enlighten Team
Unique ID: glathesis:1967-78456
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:21
Last Modified: 30 Jan 2020 15:21
URI: http://theses.gla.ac.uk/id/eprint/78456

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