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An important aspect of restoring an abutment tooth for an existing removable partial denture is the construction of a temporary crown that fits an existing clasp so that the removable partial denture can be worn during the treatment procedures. A technique is illustrated that used a soft adjustable temporary metal crown for that purpose.
OBJECTIVE: This study was designed to find out the changes in microflora on the stress-bearing areas after insertion of removable partial dentures, and in turn to explore the difference between such changes caused by metal bases and acrylic resin bases respectively. METHODS: Sixteen patients who were ready to accept removable partial dentures were selected and divided into two groups. Eight patients used metal bases while the other eight patients used acrylic resin bases. Then at the following three points: before dentures were inserted, one month after wearing and three months after wearing, the total cultivable flora were counted and the proportions of bacteria detected on the stress-bearing areas were calculated. RESULTS: No matter what type of bases was selected, the wearing of removable partial denture enhanced the accumulation of microflora on stress-bearing areas. The percentages of Candida albicans and Lactobacilli detected on stress-bearing areas also increased significantly (P < 0.05). When such changes were compared, the authors found that the increment of Candida albicans caused by acrylic resin bases was higher than that caused by metal bases (P < 0.05). CONCLUSION: The wearing of removable partial dentures forms new retention areas between the bases and the stress-bearing areas, as a result enhances the deposit of microbe and facilitate the growth of Candida albicans and Lactobacilli. Compared with increment of Candida albicans caused by metal bases, the increment relating to acrylic resin bases is more evident.
PURPOSE: The aim of our study was to explore the effects of different loading positions on the movements of the abutment tooth and denture base of removable partial denture with unilaterally designed framework (RPD-U). MATERIALS AND METHODS: The experiment was carried out with a simulation model of a mandible without left molars. The movements of abutment tooth and denture base of the unilateral and bilateral designs were due to 30N vertical load on 12 loading positions determined with a strain gauge circuitry. The effects of loading positions on the movements of the abutment tooth and denture base were compared between two designs. RESULTS: During the loading on buccal, lingual positions, and the most disto-central position the movements of the abutment tooth and denture base of the unilateral design were significantly greater than those of the bilateral design (P < 0.01). During the loading on the three mesio-central positions the movements of the abutment tooth and denture base were equal between designs, and were significantly lower than during the loading on the other positions (P < 0.01). CONCLUSION: Ending the denture teeth at the mesial cusp of second molar and positioning the occlusal contacts over the ridge crest adequately stabilize the abutment tooth and denture base of RPD-U.
This clinical report describes the use of maxillary and mandibular overlay removable partial dentures to treat a patient with class III skeletal malocclusion and a posterior open-occlusal relationship. Overlay removable partial denture therapy was used as an alternative to other options such as orthodontics and combined orthodontic/oral surgery procedures; it satisfied the esthetic and functional requirements of the patient and provided a stable occlusion. Overlay removable partial dentures are a reversible and relatively inexpensive treatment for patients with congenital or acquired anomalies, but the potential disadvantages of these prostheses include compromised esthetics when the dentures are removed; caries and periodontal disease as a result of poor oral hygiene; and veneer material fracture, debonding, discoloration, and wear.
The rationale of designing a seimprecision or precision distal-extension removable partial denture and the justification of ridge loading in distal-extension ridge impression techniques have been presented. The effectiveness of existing impression techniques in securing firm seats for abutment castings, accurate border extension of the denture base, and loading of the ridge mucosa has been evaluated. A technique has been described that overcomes the limitations of existing impression techniques for semiprecision and precision distal-extension removable partial dentures.
A method that uses Isosit material to fabricate custom-made denture teeth and denture base has been described. The advantages of this technique are the denture teeth can be made to function in harmony with dynamics of the stomatognathic system; any type of occlusal scheme can be used; the material is esthetically pleasing; it can be characterized; it can be used as a denture base material, which can also be characterized; it can be repaired, relined, or rebased with little difficulty; and laboratory procedures can be accomplished in the dental office or laboratory.
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The adequacy of prescription for fabrication of cobalt chromium removable partial dentures is often regarded as being less than ideal. This study examines the nature and quality of written instructions and master impression sent to dental laboratories in Ireland for fabrication of cobalt chromium removable partial denture frameworks. Questionnaires were issued to dental laboratories seeking specific information relating to the materials (impression materials and trays) and written instructions supplied, as well as the technicians' opinion regarding the suitability of these materials. One hundred completed questionnaires were returned. One-third of master impressions were made using a plastic stock tray and alginate; technicians felt that one-fifth of master impressions were unsuitable; almost three-fifths of written instructions were inadequate. The quality of clinical information examined was found to be less than adequate.
Removable partial dentures can meet the long-term goals of oral rehabilitation if the basic principles of treatment planning and design of the prosthesis are carried out. This article reviews the design of the components of the removable partial denture as well as several salient treatment procedures related to long-term maintenance of the supporting tissues.
A technique that forms an abutment crown to fit into an existing clasp of a removable partial denture by relining an acrylic resin pattern is described. The outer contour of the pattern is made within an irreversible hydrocolloid impression by use of Duralay autopolymerizing acrylic resin applied with precision dispensers. The pattern is formed before tooth preparation and is made approximately 0.4 mm thick. After tooth preparation, the shell pattern is relined with the same autopolymerizing resin and the existing removable partial denture is fitted over it. The gross pattern is trimmed and the margins refined on a die made from an elastomer impression. The refined pattern is cast and finished, avoiding reduction of the contours established. A second crown is similarly formed in tooth-colored autopolymerizing acrylic resin. It serves as a provisional restoration that allows the patient to wear the removable partial denture while the laboratory procedures are performed.
PURPOSE: The purpose of the study was to determine the changes in bone mineral density of the mandible in complete and removable free-end saddle denture wearers over a 6-month period. MATERIALS AND METHODS: Twenty removable partial denture patients and 20 complete denture wearers participated. Two dental panoramic radiographs were taken from each patient, the first prior to denture delivery and the second after 6 months of denture wearing. Bone mineral density measurements were performed on panoramic radiographs with a five-step copper stepwedge attached to each film cassette. Bone mineral density values of the measured regions of interest were expressed in equivalents of the stepwedge thickness (mm). RESULTS: The results revealed minor changes in bone mineral density values of the examined regions in the 6-month period. Under the distal end of complete denture saddles, the bone mineral density values decreased, whereas the values under the distal end of removable partial dentures increased. However, the difference between the first and second measurements was not significant. In each of the examined groups, the bone mineral density values at the gonion increased significantly by approximately 20%. This was attributed to the increased strain forces of the masseter muscle at the gonion after denture delivery. CONCLUSION: Significant increase of bone mineral density values was registered 2 mm above the gonion in both complete and removable partial denture wearers. Age and gender were not related to the bone mineral density changes over a 6-month period.
STATEMENT OF PROBLEM: Little is known about the outcomes of treatment with mandibular removable partial dentures provided by dentists in private dental practice. PURPOSE: This study examined 15 aspects of patient satisfaction and explored the factors found to be associated with dissatisfaction. MATERIAL AND METHODS: A questionnaire was mailed to people whose dental insurance claims included CPT Code 5214 within the last 5 years. A composite measure of treatment outcome was created by combining the responses to the 15 satisfaction items, and 10 factors were then tested statistically to determine their relationship to dissatisfaction. RESULTS: A majority of the respondents were satisfied with the prosthesis, but a substantial amount of dissatisfaction existed. Dissatisfaction was greater when there was no previous wearing experience or when there was an opposing maxillary removable partial denture. Respondents under the age of 60 expressed more dissatisfaction than did those over the age of 60, and subjects with lower levels of general health also reported less satisfaction. One third of the respondents believed their prosthesis required adjustment or replacement, and one fourth said the removable partial denture had caused a problem with the natural teeth. CONCLUSION: A majority of survey respondents treated with a mandibular removable partial denture in private dental practice were satisfied with the prosthesis, but a substantial amount of dissatisfaction existed. Dissatisfaction was related to age, health, prior experience with a prosthesis, and the type of opposing dentition.
Not only forces but also torque exerted on abutment teeth are important factors for planning the construction of distal extension removable partial dentures. The purpose of this study was to make longitudinal analysis of torque transmitted from denture base to a direct abutment tooth of these dentures with circumferential clasps. The results are summarized as follows: (i) Vertical Max. MT (maximal mean value of torque) was decreased and became constant after one or one and half months of the insertion of new dentures. (ii) Lateral Max. MT in one subject was changed from the lingual direction to the buccal direction while in another subject it was constant. (iii) In the vertical direction, there were no remarkable differences of Max. MT and Ave. T (average value of torque) between subjects. Max. MT was 5-10 x 10(-3) kgm-1 in the downward. Ave. T was 2-3 x 10(-3) kgm ss-1 in the downward and 0.3 x 10(-3) kgm ss-1 in the upward. (iv) In the lateral direction, there were considerable differences of Max. MT and Ave. T between subjects. Max. MT was less than 20 x 10(-3) kgm. Ave. MT was 2-8 x 10(-3) kgm ss-1.
The purpose of this study was to perform longitudinal measurement of forces transmitted from the denture base to retainers of lower distal-extension removable partial dentures with a conus crown telescopic system. The experimental denture was embedded with a force-detecting unit which could detect a change in lateral and vertical forces transmitted from denture base to retainers at the same time. Forces were measured during chewing of food on several separate occasions from the insertion of new dentures to about 3 months after. Max.ver (maximal mean value of vertical force) and Max.lat (maximal mean value of lateral force) were calculated from the peak level of all strokes of chewing of food at the minimum of the interocclusal distance. The results are summarized as follows: (i) There were no significant changes of Max.ver and Max.lat; (ii) There were no significant differences of Max.ver between subjects the value of which was about 20 N; (iii) There were significant differences of Max.lat between subjects the value of which was less than 15 N.
STATEMENT OF PROBLEM: Corrected impression procedures provide the best possible support to be gained from an edentulous ridge for a removable partial denture, but they are time-consuming and technique-sensitive. PURPOSE: An experimental mandibular distal extension removable partial denture was used to measure the vertical movement of denture bases during biting. MATERIAL AND METHODS: Five patients participated for whom vertical movement of denture bases was measured by comparing the thickness of plaster interocclusal records made with the denture at rest and under biting pressure. Denture bases were processed on master casts formed from final impressions made in full arch custom trays. Secondly, bases were readapted using sectional relining impressions with the same regular body polysulfide impression material. RESULTS: Statistical analysis of the vertical movement of denture bases during biting at 4 points on the right and left denture bases showed a significant decrease in vertical movement with sectional impression. The reduction was less than a 0.1 mm, a result that questions the routine use of sectional impression for every distal-extension mandibular removable partial denture. CONCLUSION: Supportive form of distal-extension edentulous ridges can be recorded successfully by full arch impressions in custom trays.
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Positive anterior rests were shown to be an essential element of design when considering stress distribution with a removable partial denture involving anterior teeth. Proximal plates often added stability and reduced stress accumulation in any one region. Distobuccal forces on the extension base adversely affected the primary canine abutment. Forces in the regions of the anterior base and central incisor abutment produced the most widespread transmission of stress throughout the arch. Greater stress throughout the arch was observed when forces were applied to the central incisor rather than to the right canine abutment. There is a need for established criteria of rest form and placement. Guidelines for using the natural crown as opposed to a positive rest seat in a restoration are needed. Continuing studies of other anterior rest forms should increasingly clarify this phase of treatment planning. The dentist should recognize the need for structural integrity in the anterior maxillary segment when designing removable partial dentures. A practical, defensible rationale for the routine use of maxillary anterior teeth as removable partial denture abutments must be established.
Despite the limited number of patients in the study, the following conclusions may be made regarding the magnitude and direction of forces transmitted to abutment teeth of extension-base removable partial dentures. 1. A technique was presented for using strain gauges to determine the magnitude and direction of forces transmitted to abutment teeth of removable partial dentures. 2. There are variations in force magnitude with a patient and between patients from chewing cycle to chewing cycle. 3. The transmitted forces vary when different removable partial denture designs are used. 4. Improving adaptation of the extension bases to the residual ridge is an excellent means for providing maximum support, increasing patient comfort, and decreasing forces to abutment teeth. 5. Extension bases apply mesially directed forces to abutment teeth during mastication. 6. Further research is needed to elucidate the effects of the various philosophies of removable partial denture design.