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The use of a temporary incisal rest at the most anterior point of a removable partial denture framework is advocated. This rest provides stabilization during intraoral and laboratory procedures when the corrected master cast technique is used.
This article has described the minimum laboratory and mouth procedures needed for fabrication of the Thompson dowel-rest removable partial denture using the modifications of (1) preconstructed dies for the dowel-rests, (2) a chrome-cobalt framework, and (3) a ball clasp retention device.
The aim of this study was to evaluate the effectiveness of an oral rehabilitation by removable partial denture (RPD). Between 1983 and 1994, 629 patients were provided with an RPD at the Dental School of the Université catholique de Louvain. All the RPDs were constructed with a cobalt-chromium framework. All the treatments were provided by dental students under the supervision of clinical instructors. At recall time (1998-2000), 269 patients could not be reached neither by telephone nor by mail and 27 had died. Consequently, 333 patients were called for clinical examination and 254 of these (76.3%) actually attended. For a total of 292 RPDs checked 1893 persistent teeth were listed, with 804 serving as abutments; more than half (57.6%) of these were crowned, for which 51 debondings were recorded. For the period of observation we listed 79 abutments lost (37 at the upper jaw and 42 at the lower jaw), i.e. 9.8% of the total number of abutments. No relation could be established between the type of the abutments (natural or crowned teeth) and the losses observed (Test of Mantel-Haenszel: P=0.9496). In the upper jaw, the percentage of abutments lost was significantly higher in the presence of free-end edentulous areas as compared with bounded edentulous areas (Test of Mantel-Haenszel: P=0.0002); this difference does not appear for the lower jaws (P=0.9558). If we deduct the 25 abutments related with the 11 non-worn RPDs and the 79 abutments lost, no change becomes apparent for 92.2% of the maxillary abutments and for 85.8% of the mandibular abutments. For the 1089 other teeth, we observed the loss of 40 teeth and the appearance of caries or new fillings for 95 teeth. The fractures of cast clasps represent 3.4%.
In this study, longitudinal changes of the occlusal force distribution ratio were examined in lower distal extension removable partial dentures with cast circumferential clasps. Occlusal force applied to the denture base and forces transmitted to the retainers were measured on several separate occasions from the insertion of new dentures to about 4 months after. Two rates of loading were chosen. One was simulated mastication (fast loading rate) and the other was 10 Ns-1 (slow loading rate). Location of the loading points were first premolar (P1), second premolar (P2) and first molar (P3) of the denture. The occlusal force distribution ratio to the retainers was calculated when a load of 20N was applied to the loading point. The results are summarized as follows: (1) The occlusal force distribution ratio at fast loading rate on P1 and P2 was changed until 1 or 1 1/2 months after the insertion of the new dentures, and then became constant. This constant value was 30% on P1, 20% on P2 and 10% on P3. (2) Slow loading rate produced a greater ratio than the fast loading rate on P2 and P3 while there were no remarkable differences in the ratio between both loading rates on P1.
The aim of this study was to evaluate the possibility of replacing removable partial denture (RPD) with fixed partial dentures on osseointegrated implants in a selective group of patients with partially edentulous lower jaws. Forty patients were evaluated to receive implants. Twenty-three patients showed a precarious oral hygiene, five patients refused the treatment (being satisfied with their RPD), six refused for economic reasons, three patients refused for fear and scepticism, one for long duration of therapy, and one was not treated because of a very marked atrophy of the alveolar crest. Finally, one patient was treated with implants. For these reasons, at the present time implants are not an appropriate treatment for introduction into large-scale public health programmes and RPD must still be considered a valid therapeutic procedure.
Improved preventive measures, clinical experience and improved laboratorial procedures have resulted in changes in the design of the removable partial denture. More attention is paid to esthetics, support of free-extension dentures and the biological consequences of the design. Possibilities in prosthodontics concerning these aspects are described.
Thirty-five patients treated at the Department of Prosthetic Dentistry, University of Umeå, who had received removable partial dentures (RPD) during the period July 1st 1981 to December 31st 1982, were interviewed regarding the use and experiences of their dentures. None of the patients had previously used an RPD. The treatment had been carried out by dentists and dental students. At the time of the interview, 1-2 1/2 years after receiving the prosthesis, 34 subjects (97%) declared that they used their RPDs during various parts of the day.
Because the arrangement of the remaining dentition may vary tremendously, the design of a removable partial denture is complicated with regard to function, esthetics, hygiene and oral comfort. Part One of this article will discuss how disassembling the RPD into its structural components and defining their functions will help the dental technician with RPD planning. Part Two will break down the components of a combination case using the same systematic approach.
An attempt was made to compare the clinical accuracy of two types of cast metals used in the fabrication of removable partial dentures as they were prepared by commercial laboratories. No comparison of the metals could be made, because the discrepancies that were found were too gross and were related to technical error. Suprabulge clasps were placed in less undercut than prescribed. Infrabulge clasps were placed in more undercut than prescribed. The laboratories produced better accuracy when they were informed of the purpose of the cast frameworks than when the frameworks were made without the knowledge that their work would be tested. One laboratory produced better results than the other under similar conditions.
A questionnaire was sent to 58 dental schools to determine what type of abutment preparation is being used in conjunction with removable partial dentures. Responses from 43 schools indicate that enamel modification and cast restorations are still the primary type of abutment preparations. Amalgam alloys are widely used, and composite and acid-etched retained restorations are also being used.
This procedure describes the use of silicone impression material to make an index that will correctly position a hinge and latch removable partial denture when a remount cast is being made. This procedure ensures that the partial denture can be retrieved with the index without stressing the retentive components of the partial denture and the remaining dentition. Recovering the remount cast is easier because the latch can be released before the impression index is separated from the cast.
From a group of 1480 patients, 1036 were treated with metal frame removable partial dentures (RPDs) at least 5 years before this analysis. Of those, 748 patients who wore 886 RPDs were followed up between 5 and 10 years; 288 patients dropped out. The 748 patients in the study groups were wearing 703 conventionally designed metal frame RPDs and 183 RPDs with attachments. When dropout patients and patients who remained in the study were compared, no differences were shown in the variables analyzed, which indicated that the dropouts did not bias the results. Survival rates of the RPDs were calculated by different failure criteria. Taking abutment retreatment as failure criterion, 40% of the conventional RPDs survived 5 years and more than 20% survived 10 years. In RPDs with attachments crowning abutments seemed to retard abutment retreatment. Fracture of the metal frame was found in 10% to 20% of the RPDs after 5 years and in 27% to 44% after 10 years. Extension base RPDs needed more adjustments of the denture base than did tooth-supported base RPDs. Taking replacement or not wearing the RPD as failure criteria, the survival rate was 75% after 5 years and 50% after 10 years (half-life time). The treatment approach in this study was characterized by a simple design of the RPD and regular surveillance of the patient in a recall system.
STATEMENT OF PROBLEM: There is no known data on the functional efficacy of different removable partial denture designs. PURPOSE: This randomized clinical trial compared the masticatory performance of two commonly used designs in 118 patients who needed a unilateral or bilateral mandibular partial denture. MATERIAL AND METHODS: One half of the patients received a partial denture with distal occlusal rests and cast circumferential clasps and the other half a partial denture with mesial rests and I-bar cast clasps. The left side, right side, and swallowing threshold masticatory tests were made with peanuts and carrots before treatment and 16 weeks after the prosthesis insertion (baseline) and thereafter at 6, 18, 36, and 60 months. RESULTS: Masticatory scores at entry were higher in the circumferential design group, but the only significant (p < 0.05) difference was found in the right side carrot performance. Both groups realized significant improvements (p < 0.001) in all performance scores with partial dentures. Mean improvements of 24.7 with peanuts and 35.8 with carrots in the right side performance scores and 19.0 in the swallowing threshold score with peanuts in the bar design group were significantly higher (p = 0.017) than the respective mean improvements of 15.9, 21.4, and 5.6 in the circumferential design group. However, no significant differences were found between the two groups for any of the 10 performance scores at baseline. CONCLUSIONS: Despite some performance differences at entry, the mean performance scores for the two groups became similar at baseline and at subsequent intervals.
The purpose of this study was to investigate the vibratory characteristics of three designs of the Class I Kennedy maxillary removable partial denture frameworks as the basic study. Their major connectors comprised a U-shaped palatal connector (UPC), single palatal bar (SPB), and anterior-posterior palatal bars (APB). Frequency response functions were measured when the framework was impacted. The modal shape was observed and the decay rate was calculated using modal analysis software. The results showed that the vibratory properties of each framework differed from each other. Within the range of frequencies from 10 to 2000 Hz, the UPC type had seven natural frequencies, while the SPB and the APB types had six. The UPC type had a greater number of natural modes accompanied by elastic deformation, including fluttering and twisting, than the other type, and the UPC type was considered to be unfavourable. The decay rate of the APB type was significantly higher than those of the UPC and the SPB types (P < 0.01).
The aim of this study was to clarify the influence of working side contacts for masticatory function for a distal extension removable partial denture. Five subjects who had edentulous arches from second premolar to second molar opposing natural teeth participated. Working side contacts were altered by using three types of artificial teeth attached to the denture base. A-form teeth made contact with opposite teeth while acting as the working side in a lateral excursion. The cusp angles of B- and C-form teeth were decreased by 10 degrees and 20 degrees, respectively compared with A-form teeth. B-and C-form teeth discluded with opposite teeth on the working side. Subjects were asked to perform two kinds of masticatory performance test. Obtained data were evaluated by the repeated-measures anova and the Tukey test for multiple comparisons. Results revealed that there was a significant difference (P=0.001) in the three types of teeth in the mixing ability test and the value of A-form teeth was statistically less value than those of the other teeth. However, there was no significant difference in the comminuting ability test. These results suggested that working side contacts between artificial teeth and opposite natural teeth influenced mixing ability, but not comminuting ability.
This clinical report describes a procedure for influencing the esthetics of a Kennedy Class III-Modification 1 removable partial denture. The acrylic resin base is eliminated, and the retentive clasp placed on the first premolars is modified. This technique is simple and inexpensive, and in the treatment presented, it resulted in complete patient satisfaction.
This study investigated the effect on the vibratory characteristics of a Class I Kennedy maxillary removable partial denture when varying its major connector design. Three types of major connector were used: the U-shaped palatal connector type (UPCD), the single palatal bar type (SPBD), and the anterior-posterior palatal bars type (APBD). Three types of denture were excited by a shaker, and frequency response functions were recorded on an FFT analyzer to identify their modal shapes. In addition, transient response simulations were carried out and the maximum displacement of each denture was obtained. The maximum displacements were statistically analyzed by ANOVA and Scheffe's F test (p < 0.01). In the modal shapes of SPBD, there were no nodal points on the major connector at all natural modes. The maximum displacement of SPBD was significantly smaller than that of UPCD and APBD. This study indicated that SPBD was a more rigid design than UPCD and APBD from the standpoint of vibratory characteristics.
The altered-cast technique, also known as the corrected-cast technique, for distal extension removable partial dentures (RPD), is not routinely utilized by dentists. Although the technique requires an additional step for both the dentist and dental technician, it offers several advantages--maximum stability, minimal stress on abutment teeth, and more predictable occlusion. The following article describes the altered-cast technique, as well as some advantages and disadvantages of the technique. A quick and easy procedure for constructing an altered-cast is also presented.