A 10-year longitudinal study was carried out on 27 patients treated with RPDs. Before the prosthetic treatment all patients were given oral hygiene motivation and instruction as well as periodontal therapy where indicated. The aim was a high level of cooperation. The RPDs, most of which were lower bilateral distal-extension dentures, were carefully planned and designed. During the follow-up period the patients were examined at yearly intervals, at which time remotivation and reinstruction regarding oral hygiene was given, and scaling, operative restorations, and prosthetic and other treatment procedures were preformed as required. Patient cooperation was excellent, and no significant deterioration of the periodontal status of the remaining teeth was found. In addition, there was a low increase in the frequency of decayed and filled tooth surfaces during the decade. The dentures showed damage and several changes during the follow-up period, conditions that necessitated various corrective prosthetic procedures.

Caries, periodontal and prosthetic findings in patients with removable partial dentures: a ten-year longitudinal study.

The purpose of this article is to discuss the clinical considerations related to increasing the occlusal vertical dimension (OVD) when restoring a patient's dentition. Thorough extraoral and intraoral evaluations are mandatory to assess the suitability of increasing OVD. In the literature, multiple techniques have been proposed to quantify OVD loss. However, the techniques lack consistency and reliability, which in turn affects the decision of whether to increase the OVD. Therefore, increasing OVD should be determined on the basis of the dental restorative needs and aesthetic demands. In general, a minimal increase in OVD should be applied, though a 5 mm maximum increase in OVD can be justified to provide adequate occlusal space for the restorative material and to improve anterior teeth aesthetics. The literature reflects the safety of increasing the OVD permanently, and although signs and symptoms may develop, these are usually of an interim nature. Whenever indicated, the increase in OVD should be achieved with fixed restorations rather than a removable appliance, due to the predictable patient adaptation. The exception to this is for patients with TMD, where increasing the OVD should still be achieved using removable appliances to control TMD-associated symptoms before considering any form of irreversible procedure.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1834-7819.2011.01640.x

Clinical considerations for increasing occlusal vertical dimension: a review.

M any studies show that the postural (rest) position of the mandible changes subsequent to dental attrition, loss of teeth, and prosthetic treatment.’ ’ Immediate changes of the mandibular posture may also be achieved in many ways, e.g., by changing the occlusal vertical dimension both in subjects with natural teeth and in those with complete dentures, by placing or removing dentures in edentulous subjects, by muscular fatigue,“-” or simply by changing the position of the head. In spite of these findings, which demonstrate an adaptability of the mandibular posture to changes in occlusal vertical dimension, the concept of constancy of the rest position has not been abandoned by all authors. Increasing the vertical dimension of occlusion is therefore often held to be a hazardous procedure in prosthetic treatment.“-” Results of experiments that increased vertical dimension both in subjects with natural teeth and with complete dentures have been interpreted as deranging the function of muscles and joints of the masticatory system.’ Clinical experience, however, supports the opinion that the masticatory system adapts well to moderate changes in the occlusal vertical dimension, “’ The present study was designed to test the effect of increasing the vertical dimension of occlusion by a modification of the method used by Christensen.’ Electromyography was added to the methods of

Effect of increasing vertical dimension on the masticatory system in subjects with natural teeth.

The neutral-zone philosophy is based upon the concept that for each individual patient, there exists within the denture space a specific area where the function of the musculature will not unseat the denture and where forces generated by the tongue are neutralized by the forces generated by the lips and cheeks. The influence of tooth position and flange contour on denture stability is equal to or greater than that of any other factor. We should not be dogmatic and insist that teeth be placed over the crest of the ridge, buccal or lingual to the ridge. Teeth should be placed as dictated by the musculature, and this will vary for different patients. Positioning artificial teeth in the neutral zone achieves two objectives. First, the teeth will not interfere with the normal muscle function, and second, the forces exerted by the musculature against the dentures are more favorable for stability and retention.

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The neutral zone in complete dentures.

Association of removable partial denture use with oral and systemic health

The dynamics of the denture space affords new premises for impression methods. Various structures limiting the denture space are described and their functional influence is analyzed. The range of action of the muscles and other structures that relate to the denture space should be recorded by an impression so that the denture can be shaped accordingly. The denture must not interfere with the action of dislodging muscles. The inclination given to secondary supporting surfaces of the denture should promote both active and passive muscular fixation of the restoration. If, in the construction of “difficult” lower dentures, due consideration is given to the dynamic nature of the denture space, it is easier to make satisfactory lower dentures than upper dentures. The number of patients needing a surgical deepening of lingual and vestibular sulci is reduced by utilizing knowledge of the denture space.

The dynamic nature of the lower denture space.

1. The introduction of a removable partial denture into the oral cavity adversely affects the prevailing ecologic situation in terms of plaque formation. 2. The rehabilitative effect of a removable partial denture may be safeguarded by controlling plaque formation by strict personal hygienic measures on the part of the patient. In particular, proximal surfaces adjacent to denture bases should be pointed out to patients as surfaces to which they must give special attention. 3. Simplification of the design of removable partial dentures can reduce their damaging potentialities. 4. Further prophylactic measures, such as topical application of fluorides and perhaps other chemicals, should also be taken.

Ecologic changes in the oral cavity caused by removable partial dentures.

Summary
A controlled trial was made using fifteen subjects and making 120 measurements with a caliper gauge between marks disposed on the upper lip and the point of the chin when maxillo–mandibular relationships were altered vertically by known amounts within a range of 6 mm. It was found that mean facial measurements could account for only half of the skeletal movement involved. The variability of soft tissue translation in relation to skeletal movement led to the conclusion that such facial measurements are inappropriate to clinical practice.

The fallacy of facial measurements of occlusal height in edentulous subjects.

It has been shown that a zone of comfort in maxillo-mandibular relationships in edentulous subjects can be identified with some precision. Whilst the neurophysiological mechanism involved has not been explained fully, the phenomenon is influenced by starting position and by fatigue. This experiment was set up to test the hypothesis that age is another significant factor in perception of the comfortable zone. A group of seventeen subjects with a mean age of 62 years and an equivalent younger group, the mean age of which was 28 years, were tested with Timmer screw jacks applied using the central approach to record the upper and lower limits of the zone fifteen times in succession for each subject. A linear statistical model was used to analyse the data from upper and lower borders separately. The results showed that the effect of making successive adjustments, whilst not significant statistically in the young group, was significant in the more elderly. Regression lines from the young group data were horizontal signifying the high degree of accuracy with which their perceptual mechanisms worked: the upwards inclination of those from the more elderly was interpreted as showing that initial appreciations were subjected to constant correction.

Long‐term changes in the perception of comfortable mandibular occlusal positions

Summary Various dynamic impression methods which are particularly useful for patients with extreme resorption of the mandibular ridge have been described. These methods were easily learned and applied by dental students. Satisfactory results were achieved with few or no corrections and most patients adapted easily to the dynamic dentures.

N. Brill

Papers

The dynamic nature of the lower denture space.

Ecologic changes in the oral cavity caused by removable partial dentures.

The fallacy of facial measurements of occlusal height in edentulous subjects.

Long‐term changes in the perception of comfortable mandibular occlusal positions

Dynamic impression methods