Maxillary Removable Partial Denture Research Articles

Implant retained, tooth and mucosa supported mandibular overdenture

The choice of a suitable prosthesis for a specific case is determined to a great extent by the number, position and salvagability of the existing teeth as well as the mucosa and underlying residual bone. Also of significance are the expectations and demands of the patient from the prosthesis. The following case report discusses the rehabilitation of a partially edentulous patient with an Implant retained, tooth and mucosa supported mandibular removable partial denture against conventional maxillary removable partial denture.

Bending properties of strengthened Ti-6Al-7Nb alloy major connectors compared to Co-Cr alloy major connectors

Although Ti-6Al-7Nb alloy has several excellent mechanical properties, its poor rigidity has limited its clinical use as a material for the fabrication of a removable partial denture (RPD) major connector. The purpose of this study was to develop and evaluate strengthening designs of Ti-6Al-7Nb RPD major connectors in an effort to increase rigidity. Four strengthening designs of Ti-6Al-7Nb alloy major connectors were developed using finite element analysis modeling: wide, thick, thick at the middle, and thick at the anterior and posterior borders. The designs had similar rigidity values to a conventional Co-Cr alloy major connector, as measured by the maximum deformation when a simulated load was applied. Next, 30 Kennedy Class II maxillary RPD specimens, using 6 different major connector designs (n = 5), were fabricated. These 6 designs included Ti-6Al-7Nb alloy RPDs with 4 different strengthening designs, a Ti-6Al-7Nb alloy RPD without strengthening designs, and a conventional Co-Cr alloy RPD as a control. The rigidity of the RPDs was evaluated by measuring strains on the major connector and force on the intaglio surface of a denture base under a 30 N loading condition. The data obtained from the 6 different RPD designs were compared using a repeated measures analysis of variance and the Bonferroni correction (alpha=.05). The strains on the major connectors and the force on the denture bases measured from the Ti-6Al-7Nb RPD without strengthening designs were significantly larger than those of the standard Co-Cr alloy RPD. The strains measured from the 4 strengthening designs were not significantly larger than those of the Co-Cr alloy RPD. The results suggest that the strengthening designs tested may improve the rigidity of the Ti-6Al-7Nb alloy major connectors and, hence, may promote clinical application for RPDs.

A survey of treatment outcomes with removable partial dentures.

The patient's satisfaction with removable partial denture (RPD) therapy has become an increasingly important factor in prosthetic treatment. This study examined patients' satisfaction with RPDs in relation to some socio-economic variables, patients' habits of wearing and cleaning RPDs, comfort of wearing RPDs and different RPDs characteristics. A questionnaire was devised for the purpose. Two hundred and five patients were required to assess satisfaction with RPDs. They graded RPDs, depending on the level of satisfaction, on scale ranging from 1 to 5. A dentist determined Kennedy classification, material and denture support, denture base shape, number of missing teeth and evaluated denture construction. Majority of the patients were satisfied with the prosthesis. The patients of a higher education level gave lower grades (P < 0.05) to aesthetics of maxillary RPDs. Almost half of the patients were wearing RPDs during the day. Most of the patients cleaned RPDs three times a day. A significant difference was found between the patients' grades for comfort of wearing mandibular RPDs and number of missing teeth and between hygiene of mandibular RPDs and habits of cleaning them. Majority of the patients treated with RPDs were satisfied with the prosthesis. Dissatisfaction was related to mastication, esthetics, number of missing teeth and maintenance of oral hygiene.

The quality of the majority of removable partial dentures worn in the United States is remarkably low

Summary Subjects The study population was 17,844 adults who had oral0689 exams as part of NHANES III, 1306 of whom wore removable partial dentures. Dental exam data were available for 1303 individuals with removable partial dentures. The study included 1603 removable partial dentures (811 maxillary and 792 mandibular). The age range of the subjects was 17 to 70+. Exposure The presence of a removable partial denture. 0689 Main outcome measure Information regarding defects in removable partial 0689 dentures was obtained from the NHANES III databases. Defects in several categories were noted. Extraoral defect categories included integrity, excessive wear of posterior teeth, and presence of reline/tissue conditioner. Intraoral defect categories included stability and retention. Main results At least 250,000 adults under the age of 40 have removable 0689 partial dentures. In this study, the number of removable partial dentures increased as the age of the patients increased. The number of maxillary removable partial dentures peaked in the 51-to-60 age group, and the number of mandibular removable partial dentures peaked in the 61-to-70 age group. In patients older than 70 years of age, the number of removable partial dentures then decreased with an increase in the number of complete dentures. Only a third of removable partial dentures werefound to be completely satisfactory, with approximately 65% of the dentures having at least 1 defect. Lack of stability was the most common defect noted for both maxillary and mandibular removable partial dentures, followed by tooth wear and lack of integrity. Retention and stability problems were more commonwith maxillary than with mandibular removable partial dentures. However, when patient age was adjusted for, the mandibular removable partial dentures were found to have more problems associated with retention, stability, and relining. Information regarding the age of the removable partial denture was not available.

Quality of removable partial dentures worn by the adult U.S. population

<h2>Abstract</h2> <b>Statement of Problem.</b> Research-based assessments of the quality of removable partial dentures (RPDs), especially within a large patient population, are lacking. <b>Purpose.</b> This study evaluated the prevalence and quality of RPDs by use of the National Health and Nutrition Survey (NHANES III) data set. <b>Material and Methods.</b> Estimates of the health and nutritional status of the American population were obtained from the NHANES III data set (1988-1994). Calibrated dentists performed dental examinations on 17,884 adults. If the subject wore an RPD, its quality was assessed with 5 criteria: integrity, tooth wear, the presence of temporary reline material or adhesive, stability, and retention. In this study, the data on RPD defects were used to assess the prevalence of problems. The original population was divided into 4 subgroups: paired RPD data=subjects wearing both maxillary and mandibular RPDs (n = 600 prostheses, 300 maxillary and 300 mandibular); single RPD data=subjects with only one RPD (n = 1003 prostheses, 511 maxillary and 492 mandibular); maxillary versus mandibular RPD data=all subjects with all RPDs (n = 1603 prostheses, 811 maxillary and 792 mandibular); and pooled RPD data=all subjects with a single RPD plus subjects with 2 RPDs, counting only the RPD with the most defects (n = 1303 prostheses, 674 maxillary and 629 mandibular). The subjects were analyzed with descriptive statistics. The distribution of defects in the RPDs was examined for possible associations with χ² tests. The paired data for patients with both maxillary and mandibular RPDs were analyzed with Wilcoxon signed rank tests. The prevalence of RPDs as a function of patient age and the association between RPD defects and patient age were analyzed with χ² tests. The results were considered highly significant at <i>P</i><.0001 and significant at <i>P</i><.05. <b>Results.</b> Of the 17,884 adults who underwent a dental examination, 1306 had RPDs. Three patients were excluded because their records were incomplete, leaving 1303 patients available for analysis. Most of the prostheses examined (65%) had at least 1 defect. Lack of stability was the most prevalent single defect. Distinctions in the type and prevalence of defects were observed between mandibular and maxillary RPDs. Mandibular RPDs had significantly more problems related to retention, whereas maxillary RPDs had significantly more problems related to the presence of reline material and to integrity defects. Tooth wear defects were significantly associated with patient age (<i>P</i><.0001). Only one third of the RPDs were considered satisfactory according to NHANES III criteria. <b>Conclusion.</b> A review of the database used in this study indicated that, in spite of a decline in tooth loss, RPDs are still used in all age cohorts, including young adults. A large number of RPDs were found to have defects. (J Prosthet Dent 2002;88:37-43.)

Quality of removable partial dentures worn by the adult U.S. population

Statement of Problem. Research-based assessments of the quality of removable partial dentures (RPDs), especially within a large patient population, are lacking. Purpose. This study evaluated the prevalence and quality of RPDs by use of the National Health and Nutrition Survey (NHANES III) data set. Material and Methods. Estimates of the health and nutritional status of the American population were obtained from the NHANES III data set (1988-1994). Calibrated dentists performed dental examinations on 17,884 adults. If the subject wore an RPD, its quality was assessed with 5 criteria: integrity, tooth wear, the presence of temporary reline material or adhesive, stability, and retention. In this study, the data on RPD defects were used to assess the prevalence of problems. The original population was divided into 4 subgroups: paired RPD data = subjects wearing both maxillary and mandibular RPDs (n = 600 prostheses, 300 maxillary and 300 mandibular); single RPD data = subjects with only one RPD (n = 1003 prostheses, 511 maxillary and 492 mandibular); maxillary versus mandibular RPD data = all subjects with all RPDs (n = 1603 prostheses, 811 maxillary and 792 mandibular); and pooled RPD data = all subjects with a single RPD plus subjects with 2 RPDs, counting only the RPD with the most defects (n = 1303 prostheses, 674 maxillary and 629 mandibular). The subjects were analyzed with descriptive statistics. The distribution of defects in the RPDs was examined for possible associations with χ2 tests. The paired data for patients with both maxillary and mandibular RPDs were analyzed with Wilcoxon signed rank tests. The prevalence of RPDs as a function of patient age and the association between RPD defects and patient age were analyzed with χ2 tests. The results were considered highly significant at P<.0001 and significant at P<.05. Results. Of the 17,884 adults who underwent a dental examination, 1306 had RPDs. Three patients were excluded because their records were incomplete, leaving 1303 patients available for analysis. Most of the prostheses examined (65%) had at least 1 defect. Lack of stability was the most prevalent single defect. Distinctions in the type and prevalence of defects were observed between mandibular and maxillary RPDs. Mandibular RPDs had significantly more problems related to retention, whereas maxillary RPDs had significantly more problems related to the presence of reline material and to integrity defects. Tooth wear defects were significantly associated with patient age (P<.0001). Only one third of the RPDs were considered satisfactory according to NHANES III criteria. Conclusion. A review of the database used in this study indicated that, in spite of a decline in tooth loss, RPDs are still used in all age cohorts, including young adults. A large number of RPDs were found to have defects. (J Prosthet Dent 2002;88:37-43.)

On the accuracy of some in vitro models for mechanical studies of maxillary removable partial dentures

Objectives. Comparative in vitro/in vivo studies show wide differences in functional strain magnitudes and patterns of functional strain distribution in prosthetic devices. The aim of this study was to evaluate the accuracy of three in vitro models for biomechanical studies of prosthetic devices. Methods. Strain gages were attached to the test RPDs of six subjects. In vitro maxillary models with simple (model A), intermediate (model B) and advanced (model C) features for the anatomical simulation of supporting structures were manufactured for each subject. The dentures were subjected to two separate series of standardized functional and laboratorial loading tests. The principal maximum strain value ( ε 1) obtained for each gage and experiment was used to calculate the intra-experiment variance and inter-experiment variance for the in vivo and in vitro experiments. The integrated strain gage difference value between the in vitro and in vivo data ( Σ diff) was calculated for every loading test and compared to the in vivo inter-experiment variance with ANOVA and Scheffés test. Results. The bite forces recorded were similar for each subject and loading position and between the two loading sessions. The inter- and intra-experiment variance was found to be higher for in vivo loadings than for in vitro. Results showed that the ( Σ diff) values for model B and model C were significantly different from the in vivo strain inter-experiment variance ( p<0.05). Significance. This study showed that the anatomical simulation of in vitro models is insufficient to allow for accurate mechanical analyses of maxillary RPDs and that only simple verifications of the strain levels in prosthetic appliances can be attained in vitro.

A novel sensor for bite force determinations

Objectives. The clinical usefulness, accuracy and precision of a novel bite force sensor based on force sensing resistors were tested in six subjects wearing maxillary removable partial dentures retained by conical crowns. Methods. The surfaces of the sensor were manufactured in a silicone material that had mechanical properties similar to those of tough foodstuffs. In two separate series of standardized bite force tests, submaximum force levels were recorded with the sensor and with a strain gaged bite fork. Subjects were assisted in the loading tests with visual feedback instrumentation. Reliability estimates for the bite force sensor were calculated in order to show their reproducibility. Strain gages attached to the prostheses were used to determine the pattern of force distribution during loading tests. The bite force results obtained with the new bite force sensor and with the bite fork were analyzed with ANOVA and Scheffés tests. The strain patterns registered with strain gages were analyzed with F-test. Results. The bite force sensor and the bite fork transducer showed no statistically significant differences in respect of intra-individual bite force levels (range 50–300 N). The bite forces registered with the new sensor were dependent on the loading position ( p<0.05), sex ( p<0.05) and test subject ( p<0.05). The reliability of the new sensor for submaximum bite forces was calculated to be 93%. Strain gage results showed that the new sensor generated strain patterns of less variance ( p<0.05) than the bite fork and therefore allowed for higher precision during biting tests. Significance. The presented instrument has such clinical merits, as to favor its use in experimental clinical studies on the biomechanics of prosthetic appliances.

Treatment outcomes with mandibular removable partial dentures: A population-based study of patient satisfaction

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. (J Prosthet Dent 1998;80:36-45.)

局部床義歯粘膜面部の重合に伴う寸法変化 第ｌ報 上顎左右犬歯残存ＫｅｎｎｅｄｙＩ級ｌ類ケースについて

The dimensional changes of denture base of maxillary removable partial denture (Kennedy class I division 1) following polymerization were measured by using the three-dimensional measurement system for 4 weeks. The maxillary partial dentures processed by three kinds of denture base resin (heat-cured, pour-type, microwave-cured) were compared. All dentures shrank toward the center of the denture immediately after deflasking. These dentures showed linear shrinkage of 0.38% to 0.54% for the heat-cured, 0.23% to 0.52% for the pour-type, and 0.34% to 0.40% for the microwave-cured resins. After deflasking up to 4 weeks, the heat-cured dentures, except alveolar groove, gradually expanded; the pour-type dentures gradually expanded and reached the original model size, but the buccal flange continued to shrink toward mucosal surface of denture; the microwave-cured dentures gradually expanded.

Button versus buttonless castings for removable partial denture frameworks

Casting removable partial dentures (RPDs) without completely filling the sprue channels and generating casting buttons would result in saving metal and making more defect-free castings. This investigation tested whether a complete and sound RPD casting can be obtained when a minimal amount of metal is used, A factorial experimental design, three spruing methods, two metal feeding directions, and two different weights of metal were used to cast 60 Kennedy class II, modification 1 RPDs. The metal used to cast each framework was either enough to result in a full button or in no button. Visual and radiographic examinations and counting of defects were made by two independent operators who were unaware of the spruing method, feeding direction, or amount of metal used to make the framework. The completeness of the casting and the presence of porosities were evaluated for clasps, major connectors, and meshworks. The use of minimal metal to cast RPDs was equally as successful as using enough for a full button, provided that the appropriate spruing arrangement and metal feeding direction were chosen. Indirect metal feeding for maxillary RPDs was successful with the proper spruing arrangement.

Incidence of various classes of removable partial dentures

The purpose of a classification for removable partial dentures (RPDs) is to simplify identification and enhance its teaching. A classification also allows a longitudinal comparison of various classes of RPDs to determine whether the teaching of RPD design is consistent with the relative frequencies of RPD use. This study surveyed the types of removable partial dentures being fabricated in a regional dental laboratory and compared these findings with data from previous studies. Results indicate that mandibular RPDs are more common than maxillary RPDs and the class I mandibular RPD is the most common type of RPD for either dental arch. A palatal strap was the most frequently used maxillary major connector and a lingual bar was used three times more often than a lingual plate in the mandibular arch. Cast circumferential clasps were used twice as often as RPI clasp designs. The percentage of Kennedy class I RPDs was 40%, class II 33%, class III 18%, and class IV 9%. Comparisons with a previous study indicate the percentage of Kennedy class II has increased, whereas class I, class III and class IV RPDs have not changed significantly. Findings of the study indicate that the frequency of use of the various types of RPDs has changed in the past 30 years.

A modified finish line allowing for tooth loss under a maxillary removable partial denture

A modified finish line allowing for tooth loss under a maxillary removable partial denture

Clinical evaluation of removable partial denture rest seat adaptation

The clinical relationship between the removable partial denture cast occlusal rest and the corresponding rest seat was examined. Under the conditions of the study, it was found that rests of mandibular Class I and II removable partial dentures fit significantly better than those of mandibular Class III and IV prostheses. No significant difference was noted between similar types of maxillary removable partial dentures in this regard. In evaluating the fit of specific portions of the occlusal rest, it was found that the marginal ridge zone was more closely adapted to the rest seat than other zones for all types of removable partial dentures. However, contact, as defined in this analysis, was found to exist on a random basis in all four quadrants of the occlusal rests evaluated. In spite of this fact, one fifth of the occlusal rests did not contact the opposing rest seat at any point. Improved fit with length of service was not substantiated by a cross-sectional analysis. Suggestions were made to assist the clinician in achieving a better fit between the framework and dentition in removable partial dentures.

Modified finish line in distal extension maxillary removable partial dentures

Finish line modifications provide adjustability and facilitate relining in the hamular notch as changes in tissue contour dictate. Time problems and inconvenience of dealing with a metalacrylic resin junction, are eliminated while necessary postinsertion procedures are accomplished. In addition, the acrylic resin denture base is retained securely to the metal framework for the entire length of the external finish line.

Impression technique for maxillary removable partial dentures

T he preferred design for major connectors of maxillary removable partial dentures is a broad palatal plate or anterior and posterior palatal bars.‘” Regardless of which design is selected, intimate contact between the major connector and the palatal mucosa is essential to obtain maximum stability and prevent food entrapment under the major connector. The cast recovered from the master impression must be an accurate duplication of both the teeth and the palatal tissues. Irreversible hydrocolloid has been recommended as an acceptable material to use in making impressions for metal framework fabrication.‘* ‘, 5 A recent study has demonstrated that properly manipulated irreversible hydrocolloid will provide adequate accuracy in the region of the teeth. However, a clinically significant amount of distortion would be expected in the hard palate.6 The amount of distortion that occurs in this region is of sufficient magnitude to prevent contact of the major connector with the palatal mucosa. Techniques tal compensate for this inaccuracy of the impression have been suggested. One alternative is to use a slightly thicker mix of alginate (irreversible hydrocolloid) in an attempt to minimize the amount of distortion attributed to “slumping” of the impression material.’ Alter:ing the water/powder ratio of the irreversible hydrocolloid from that recommended by the manufacturer can impair certain characteristics of the gel and weaken the final set material.’ Another suggestion has been to place a mound of utility wax in the palatal part of the tray to support the impression material and prevent slumping or distortion5 A potential problem witb this technique is uneven application of the wax, resulting in impression material that is either too thick or too thin in the palatal area. The potential for adhesive failure between the wax and the irreversible hydrocolloid exists and would result in a lack of accurate (duplication. Further, distortion of the

Hinge for a unilateral maxillary arch prosthesis

This article describes a technique for the fabrication of a hinge that may be incorporated into a maxillary removable partial denture with a unilateral distal-extension denture base. The hinge breaks the stress that would be transmitted to the dentulous arch segment through the retentive portion. Figs. 7 and 8 show a typical arch situation where the Palatar hinge may be incorpoated.

The acrylic resin base maxillary removable partial denture: Technical considerations

Technical considerations have been outlined that will help to produce a transitional removable partial denture that may be placed in the mouth with a minimal amount of adjustment.

Anterior rests for maxillary removable partial dentures

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.

Secondary palatal impressions for major connector adaptation

A method of constructing maxillary removable partial dentures with a secondary corrective impression of the palatal areas has been described. It has the advantage of simplicity in obtaining a major connector closely adapted to the tissue surface. It has the disadvantage of increased bulk and lack of thermal conductivity. It is a workable approach to a common problem.