Fabrication of interim acrylic resin removable partial dentures with clasps

An orderly sequence of steps for construction of an interim acrylic resin partial denture has been presented. The technique allows the dentist to fabricate an effective restoration that has a definite path of insertion and removal that can be placed in the patient's mouth with little time spent on adjustment and correction. This technique may be used with heat- or cold-curing acrylic resin.     

Clinical survey of acrylic resin removable denture repairs with glass-fiber reinforcement

PURPOSE: The aim of this study was to evaluate clinical usefulness and durability of continuous glass-fiber reinforcement in repair of acrylic resin removable dentures. MATERIALS AND METHODS: Fractured removable dentures without reinforcement, with conventional metal-wire reinforcement, or with mesh reinforcement were collected from two dental schools in Finland. The total number of dentures was 51 and the number of patients was 48. During the repair, the dentures were reinforced with a polymer-preimpregnated E-glass fiber at the region of the fracture. The fibers were used as partial fiber reinforcement, i.e., only the weakest part of the denture was reinforced. Follow-up time varied from 4 months to 4.1 years. After the follow-up period, possible fractures and discoloring were visually inspected. Possible irritation of oral mucosa by glass fibers and the general shape of the denture were also evaluated. RESULTS: In 88% of the cases, there was no need for adjustment at the region of partial fiber reinforcement, and the clinical condition of the dentures was good. Glass fibers did not irritate the oral mucosa. In the case of refracture or hairline fracture, positioning of the partial fiber reinforcement was incorrect or the reinforcement had been used incorrectly (the wetting of the reinforcement with denture base resin was inadequate). CONCLUSION: Polymer-preimpregnated partial fiber reinforcement seems to be useful in eliminating fractures of acrylic resin removable dentures. However, this study emphasizes the importance of correct positioning and accurate laboratory technique when partial fiber reinforcement is used.     

All-ceramic inlay-retained fixed partial dentures: preliminary results from a clinical study

OBJECTIVES: The objective of this study was to evaluate the clinical performance of zirconia-based all-ceramic fixed partial dentures anchored by inlays. METHODS: A total of thirty FPDs, manufactured using a zirconia frame and veneered with press ceramic, were anchored by use of inlay retainers. All FPDs were designed to replace one missing molar and were adhesively luted by use of one of two different resin cements. Documentation included failures and other complications, plaque accumulation, and aesthetic and functional performance. Statistical analysis was performed using a cox-regression model. RESULTS: During the 12 months observation period a total of thirteen clinically relevant complications occurred-four delaminations of the veneer and six decementations. Three FPDs had to be replaced because of a fracture of the framework. The cement chosen, the location, and the design of the retainer had no statistically significant effect on the occurrence of complications. During the observation period, accumulation of plaque on the abutment teeth was not significantly greater than on reference teeth. Postoperative sensitivity did not differ significantly between the different luting cement groups. The aesthetic and functional performance of the FPDs was acceptable. CONCLUSIONS: Improved adhesion between resin cement and inlay retainer is desirable before general recommendation of all-ceramic inlay-retained FPDs. Use of different luting cements seems to have no effect on the occurrence of complications.     

Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided.     

Glass fiber reinforced composite resin as an intracanal post--a clinical study

Restoration of primary incisors, which have been severely damaged by early childhood caries or trauma, is a difficult task for the pediatric dentist. With the introduction of new adhesive systems and restorative materials, alternative approaches for treating these teeth have been proposed. MATERIALS: Ten healthy children aged between 3-4 years who had 28 grossly destructed primary maxillary incisors requiring intra canal retention were selected for the study. Following root canal treatment, either a Glass Fiber Reinforced Composite Resin (GFRCR everStick,, Finland) or an omega shaped stainless steel wire were placed as intracanal posts in these teeth. Flowable composite was used for cementation of posts and also to build up the coronal structure using celluloid strip crowns. Both types of intracanal posts were evaluated for retention and marginal adaptation at 1, 6 and 12 months. The data obtained was subjected to statistical analysis. CONCLUSION: GFRCR intracanal posts showed better retention and marginal adaptation than omega shaped stainless steel wire posts.     

充填方式对种植义齿固定螺丝孔粘接强度及密封性的影响研究

 目的　研究不同充填方式封闭种植义齿固定螺丝孔对粘接强度及密封性的影响。方法　制作上颌第一前磨牙种植螺丝固位氧化锆冠试件80件，按照粘接前是否喷砂预处理、充填树脂种类、充填深度随机均分为8组，分别置于墨水溶液7 d，万能材料实验机上对螺丝孔内树脂充填体进行推出测试，记录树脂充填体脱粘接时的瞬间载荷，并取出树脂充填体，显微镜下观察记录并比较充填体染色的范围。结果    是否喷砂及树脂种类对粘接强度的影响均具有统计学意义（P < 0.01）；充填体厚度会显著影响粘接断裂载荷大小（P < 0.01），但对粘接强度的影响无统计学意义（P = 0.09）。喷砂后使用3 mm流动树脂充填微渗漏最少，不喷砂使用2 mm膏状树脂微渗漏最严重，是否喷砂、树脂种类及充填体厚度均对微渗漏有显著影响（P < 0.05）。结论    固定螺丝孔表面喷砂处理可增加粘接强度，减少微渗漏。流动树脂封闭种植义齿固定螺丝孔可获得相似的密封性及高于普通膏状树脂的粘接强度。在一定范围内，增加充填体厚度有助于提高固定螺丝孔封闭树脂的咬合承受力并减少微渗漏。     

Complications and failures in removable partial dentures: a clinical evaluation

The design of removable partial dentures (RPDs) is an important factor for good prognostication. The purpose of this study was to clarify the effectiveness of denture designs and to clarify the component that had high rates of failure and complications. A total of 91 RPDs, worn by 65 patients for 2-10 years, were assessed. Removable partial dentures were classified into four groups: telescopic dentures (TDs), ordinary clasp dentures (ODs), modified clasp dentures (MDs) and combination dentures (CDs). The failure rates of abutment teeth were the highest and those of retainers were the second highest. The failure rates of connectors were generally low, but they increased suddenly after 6 years. Complication and failure rates of denture bases and artificial teeth were generally low. Complication and failure rates of TDs were high at abutment teeth and low level at retainers. Complication and failure rates of ODs were high at retainers.     

Treatment with removable partial dentures: a longitudinal study. Part I

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 fitted for these 254 patients, 218 (74.7%) were still being worn at the time of the check-up. Seventy-four dentures were considered to be 'failures', either because they were replaced by another RPD or by a complete denture, or because they had actually never been worn. The statistical analysis (Mantel-Haenszel and Kaplan-Meier) shows that the number of failures is significantly higher at the lower jaw compared with the upper jaw. Most of the failures are attributable to RPDs with free-end saddles and, in particular, to class I mandibular dentures. The patients are wearing their denture(s) mostly continuously (63.6%) and award a high degree of satisfaction to their denture. In general, the results recorded may be considered as very satisfactory, all the more so as we have no regular recall procedures established at our school and as check-up asked for spontaneously by the patients in the course of the period of observation are most of the time occasional or non-existent.     

Treatment with removable partial dentures: a longitudinal study. Part II

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%.     

Esthetic options for the fabrication of removable partial dentures: a clinical report.

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.     

Variation in blood flow of supporting tissue during use of mandibular complete dentures with hard acrylic resin base and soft relining: a preliminary study

PURPOSE: This study investigated the influence of hard and resilient polymerized acrylic resin base materials on the blood flow of the supporting underlying mucosa of mandibular denture wearers during different denture-wearing periods. MATERIALS AND METHODS: Measurements were carried out on 20 complete denture wearers, 10 with hard bases and 10 with soft ones. The mucosal blood flow underlying the dentures was measured bilaterally in the canine and molar regions using a laser Doppler flowmeter. Baseline measurements were performed before denture wearing and after the dentures were worn for 1 week, 1 month, 3 months, and 6 months. RESULTS: Mean blood flow to the mucosa after 1 week was significantly lower in the measured regions than that obtained before the dentures were worn. Blood flow in the canine region returned to almost normal levels 6 months after beginning to wear complete dentures. However, blood flow in the molar region of the denture wearers in the hard base group increased after 6 months, whereas blood flow values did not return to the levels recorded before denture insertion in the soft lining group. CONCLUSION: It appears that wearing dentures hinders blood flow to denture-supporting tissues, even when soft liners are used.     

Minor connector designs for anterior acrylic resin bases: A preliminary study

The effect of nine different designs on the strength of acrylic resin attachment to the partial denture framework in anterior edentulous spaces was tested. Thirty metal frameworks, incorporating nine different designs and a control, were fabricated. Acrylic resin was processed to these frameworks, and the resin was subjected to a shear force. The framework designs offering strong retention for acrylic resin bases allowed the use of a greater bulk of acrylic resin projecting through openings in the metal retention design.     

The influence of reinforcement on strain in maxillary complete dentures: a preliminary report

The purpose of this study was to test intraorally the effect of a cobalt-chromium cast reinforcement embedded in the denture base of a maxillary complete denture on the distribution of stress. Eight subjects were selected randomly, and three designs of a cobalt-chromium alloy bar were embedded in the dentures. A strain gauge was attached at three positions around the midline of the polished surface of each denture. Strain in the reinforced dentures was significantly less than strain in dentures without reinforcement. These observations suggest that a cast cobalt-chromium reinforcement reduces strain and could contribute to fracture avoidance deformation in maxillary complete dentures.     

Maxillary zirconia implant fixed partial dentures opposing an acrylic resin implant fixed complete denture: a two-year clinical report

The fabrication of fixed implant-supported prostheses for edentulous patients may be performed using all-ceramic or acrylic resin materials. This clinical report describes the fabrication and 2-year follow-up of maxillary zirconia implant fixed partial dentures opposing a mandibular acrylic resin screw-retained fixed complete denture.