Influence of food platform width of mandibular removable partial denture on food mixing ability

The aim of this study was to clarify the influence of food platform width on food mixing ability in patients with mandibular removable partial dentures (RPDs). Twelve subjects (six males and six females, mean age 56.8 years) with intact dentition except for unilaterally missing mandibular first and second molars participated in the study. The food platforms of their RPDs were made of light polymerized composite and three platform conditions were evaluated. A food platform (Control condition) had 7 mm width with a central focus on the top of the residual ridge. Narrowed platforms (5 mm) were created by trimming a lingual portion (Buccally oriented occlusion, Buccal condition) or a buccal portion (Lingually oriented occlusion, Lingual condition) from the control. Subjects chewed a standardized wax cube which provided an estimate of food mixing ability [Mixing Ability Index (MAI)] for each of the three platforms. A significant effect (P < 0.001) on the MAI was found for food platform type (repeated measures one-way analysis of variance). Tukey multiple comparisons found significant differences of MAI between Control condition (1.05 +/- 0.26) and Buccal condition (0.86 +/- 0.23) (P = 0.032), and between Control and Lingual condition (0.54 +/- 0.37) (P < 0.001). Furthermore, MAI with Lingual condition was significantly smaller than that with Buccal condition (P < 0.001). These results suggest that reduction in the width of the food platform may impair masticatory function and the buccal portion of mandibular food platform of RPD is more critical for food mixing than the lingual portion of the platform.     

A structural equation model relating objective and subjective masticatory function and oral health‐related quality of life in patients with removable partial dentures

Summary The aim of this study was to investigate the relationships between objective masticatory function with respect to masticatory performance and food mixing ability, patients’ perception of chewing ability and oral health‐related quality of life (OHRQoL). Partially dentate patients with removable partial dentures (n = 131, mean age 67·1 year) participated in the study. Four tests were performed to evaluate objective and subjective masticatory function and OHRQoL. Masticatory performance and food mixing ability were assessed using peanuts or a two‐coloured wax cube as test items. Patients’ perception of chewing ability was rated using a food intake questionnaire. OHRQoL was measured using the Japanese version of the oral health impact profile. A structural equation model was constructed based on hypothesis in which objective masticatory function would be related to OHRQoL via perceived chewing ability as a mediator. Structural equation modelling analysis found a statistically significant medium effect of perceived chewing ability on OHRQoL and statistically significant medium or small effects of masticatory performance on perceived chewing ability and OHRQoL (P < 0·05); however, the effect of food mixing ability on perceived chewing ability or OHRQoL was not statistically significant (P > 0·05). A fit index indicated that the model fitted well to the data (Goodness‐of‐fit index = 0·99). These results suggest that perceived chewing ability is a critical factor for OHRQoL and that masticatory performance rather than food mixing ability is important for perceived chewing ability and OHRQoL in patients with removable partial dentures.     

Influence of working side contacts on masticatory function for mandibular distal extension removable partial dentures

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.     

可摘局部义齿修复1126例临床分析

目的：对1126例可摘局部义齿进行分析，为临床关于可摘局部义齿修复牙列缺损积累经验。方法：随机选取1126件义齿修复病例，分析牙齿缺损位置、数量与性别和年龄的关系及修复体的类型，并对采用新技术进行的特殊设计进行分析。结果：上颌牙缺失多于下颌，不同年龄组缺牙好发部位不同，青年组以前牙缺失为多，其他年龄组以后牙缺失为多。男女两组中平均失牙数随年龄增加而增加，但与性别无关，在各类可摘局部义齿设计中，第5类最多。结论：可摘局部义齿制作简便，适应症广，目前仍然在修复治疗中发挥着重要的作用。     

Failures in the rehabilitation treatment with removable partial dentures

Abstract

Background. Despite being functional and having aesthetic benefits, the acceptance of patients regarding the use of removable partial dentures (RPDs) has been low. In part, this is due to the deleterious effects that causes discomfort to the patient. Success depends not only on the care expended by the patient, including daily care and oral hygiene, but also on common goals set by their professional and clinical staff, aiming beyond aesthetics, to incorporate issues of functionality and the well-being of patients. Methods and results. For rehabilitation treatment with RPDs to reach the desired level of success without damaging the support structure, all the steps (diagnose, cavity preparation, adaptation of the metal structures, functional of distal extension and posterior follow-up) in the rehabilitative treatment should be carefully developed. A literature review was carried out, searching through MEDLINE (PubMed) articles published between 1965 and December 2012 including clinical trials and reviews about the use of RPDs. Conclusions. This study describes factors that lead to failures and complications in oral rehabilitation through the use of RPDs and suggests possible solutions.     

老年人可摘局部义齿折裂的设计因素

目的：分析老年人可摘局部义齿折裂的设计因素，旨在提高可摘局部义齿的设计水平和质量。方法：通过对临床上216例老年人可摘局部义齿折裂病例的观察，根据王征寿分类法归纳各类义齿折裂的常见类型，分析其中的薄弱环节和设计因素。结果：一类义齿咬合低时易发牛近远中向折裂；二类义齿咬合紧时常在游离端远中发生近远中向折裂，尤以上颌结节和磨牙后垫部位多见；三类和五类义齿的舌腭侧基托常在两个缺牙区之间尤其是靠近缺牙区的部位发牛与牙弓相交叉的折裂；四类义齿常发牛人工牙脱落或腭侧基托横折；人类义齿舌腭侧基托易发生纵折，折裂线常位于人工牙与基牙交界处。以上可摘局部义齿折裂的发生部有其设计与制作上的原冈，作者对此提出了相应的对策。结论：应特别注重义齿的抗折设计，这是提高可摘局部义齿修复质量的重要环节。     

Parallel bonded cast attachments for removable partial dentures

The original design of a semi-precision extra-coronal attachment for partial dentures is illustrated, and its fabrication in a cast non-precious bondable alloy is described. A step-by-step method is also described of bonding multiple attachments in parallel for the retention and support of removable partial dentures. Clinical cases are illustrated. The results of trials indicate that the method is clinically viable and, in selected cases, appears to offer distinct advantages over existing retention systems.     

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.     

Comparisons between a mixing ability test and masticatory performance tests using a brittle or an elastic test food

Summary  A variety of chewing tests and test items have been utilized to evaluate masticatory function. The purpose of this study was to compare a mixing ability test with masticatory performance tests using peanuts or gummy jelly as test foods. Thirty-two completely dentate subjects (Dentate group, mean age: 25·1 years) and 40 removable partial denture wearers (RPD group, mean age: 65·5 years) participated in this study. The subjects were asked to chew a two-coloured paraffin wax cube as a test item for 10 strokes. Mixing Ability Index (MAI) was determined from the colour mixture and shape of the chewed cube. Subjects were asked to chew 3 g portions of peanuts and a piece of gummy jelly for 20 strokes, respectively. Median particle size of chewed peanuts was determined using a multiple-sieving method. Concentration of dissolved glucose from the surface of the chewed gummy jelly was measured using a blood glucose meter. Pearson's correlation coefficient was used to test the relationships between the MAI, median particle size and the concentration of dissolved glucose. Mixing Ability Index was significantly related to median particle size (Dentate group: r  = −0·56, P  < 0·001, RPD group: r  = −0·70, P  < 0·001), but not significantly related to glucose concentration (Dentate group: r  = 0·12, RPD group: r  = 0·21, P  > 0·05). It seems that ability of mixing the bolus is more strongly related to the ability of comminuting brittle food than elastic food.     

老年人夹板式可摘局部义齿设计体会

目的：总结老年牙列缺损患者采用夹板式可摘局部义齿修复的设计体会，供临床工作参考。方法：针对老年人口腔生理、解剖特点，对89例老年牙列缺损患者分别采用3种形式的夹板式可摘局部义齿修复，并作1—3年追踪复查。检查项目为患者主观感觉、牙周情况、咀嚼功能。结果：患者主观感觉满意度为：93．26％；牙周情况正常率为：92．13％；咀嚼功能良好率为：98．88％；修复效果满意。结论：对老年牙列缺损患者采用夹板式可摘局部义齿修复，可在恢复缺失牙功能的同时，又对余留牙起到分散[牙合]儿、减轻牙周组织负荷的作用，有利于牙周组织恢复健康。     

��ժ�ֲ���ݻ��ߵ��˸��������޸�����ȵ�������о�

目的    了解可摘局部义齿（removable partial denture,RPD）修复患者的基本情况以及人格特征,分析人格特征与修复满意度之间的关系。方法    2007年6月至2010年3月使用艾森克人格问卷及可摘局部义齿满意度调查表对盘锦市第一人民医院口腔科108例可摘局部义齿修复患者进行调查,采用统计学方法进行相关性分析。结果    对语言和咀嚼能力满意的患者所占比例较高,与其他分项比较,差异有统计学意义（P < 0.05）。N量表得分与固位稳定、舒适度及满意度问卷总分之间呈负相关（r = -0.31 ~ -0.24）,且以N得分 = 60为界,N得分> 60 和≤ 60两组之间差异具有统计学意义（P < 0.05）。结论    情绪稳定、性格乐观、自控性强的缺牙患者较神经敏感、情绪不稳、自控性差者容易接受可摘局部义齿修复,各项满意度较高。     

Effect of prosthetic restoration on masticatory function in patients with shortened dental arches: a multicentre study

The aim of this multicentre study was to investigate the effect of prosthetic restoration for missing posterior teeth on mastication in patients with shortened dental arches (SDAs). Partially dentate patients who had an intact teeth in anterior region and missed distal molar(s) (2–12 missing occlusal units) classified as Kennedy Class I or Class II were recruited from seven university‐based dental hospitals in Japan. Of the 125 subjects who underwent baseline (pre‐treatment) and follow‐up/post‐treatment evaluation, 53 chose no replacement of missing teeth and 72 chose treatment with removable partial dentures (n = 53) or implant‐supported fixed partial dentures (n = 19). Objective masticatory performance (MP) was evaluated using a gummy jelly test. Perception of chewing ability (CA) was rated using a food intake questionnaire. In the no‐treatment group, mean MP and CA scores at baseline were similar to those at follow‐up evaluation (P > 0·05). In the treatment group, mean MP after treatment was significantly greater than the pre‐treatment mean MP (P < 0·05). However, the mean perceived CA in the treatment groups was similar at pre‐ and post‐treatment (P > 0·05). In a subgroup analysis of subjects in the treatment group, subjects with lower pre‐treatment CA showed a significant CA increase after treatment (P = 0·004), but those with higher pre‐treatment CA showed a significant decrease in CA (P = 0·001). These results suggest that prosthetic restoration for SDAs may benefit objective masticatory performance in patients needing replacement of missing posterior teeth, but the benefit in subjective chewing ability seems to be limited in subjects with perceived impairment in chewing ability before treatment.     

Effect of complete and partial removable dentures on chewing movements

Partial or complete edentulism impairs mastication. However, it is unclear how the chewing cycle is affected by prosthetics. We evaluated the chewing movements of patients fitted with complete (CD) or removable partial denture (RPD). A total of 29 subjects were kinesiographically evaluated during chewing of peanuts and Optocal portions in a random sequence. The subjects were divided into two groups according to prosthesis type. Group RPD was composed of 14 partially edentulous patients using a lower distal extension RPD (mean age 61 ± 8 years), and group CD contained 15 completely edentulous patients using CD (mean age 65·9 ± 7·9 years) in both jaws. Opening, closing, occlusal and masticatory cycle times, movement angle (opening and closing), maximum velocity (opening and closing), total area and chewing cycle amplitudes were evaluated. The results were subjected to anova and Tukey's HSD test at a significance level of 5%. The RPD group exhibited shorter opening and closing phases and masticatory cycle time (P < 0·05). Maximum velocities were also higher in the RPD group, irrespective of the test material (P < 0·05). The area and amplitude of the chewing envelope was smaller in the CD group (P < 0·0001). The test material did not influence chewing cycles in any of the parameters evaluated (P > 0·05). RPD wearers use a faster chewing sequence with greater vertical and lateral jaw excursions compared with CD wearers.     

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.     

Effect of implant support on distal extension removable partial dentures: in vitro assessment

The implants in implant-supported removable partial dentures (RPDs) are placed in the edentulous ridge to stabilize the RPD and minimize the resultant rotational movement. This study investigated the effect of implant placement on RPD stability. A model simulating a mandibular bilateral distal extension missing was fabricated using epoxy resin and silicone impression material as thin (1 mm) and thick (2 mm) soft tissues. Five pressure sensors (PS-10K, Kyowa, Tokyo, Japan) were attached near the left and right first molars (#36 and #46), first premolars (#34 and #44) and medio-lingual alveolar crest. Five bilateral distal extension RPDs with Co-Cr frameworks were conventionally fabricated. After the implants were placed at the bilateral second molar areas, healing caps (4.5 mm high) were connected to the denture base with autopolymerized resin to support the RPD. As in a conventional RPD, sealing screws were placed without connecting them. Loads up to 5 kg were applied, and the pressure and displacement of the RPDs (n = 5) were simultaneously measured and analysed using the Wilcoxen test (alpha = 0.05). There was less pressure on both thin and thick soft tissues, the #36, #46 and the medio-lingual alveolar crest from the implant-supported RPD than from the conventional RPD (P < 0.05). There were no significant differences in pressure on #34 and #44 between the two RPDs (P > 0.05). There was significantly less denture displacement of the implant-supported RPD than of the conventional denture (P < 0.05). Implant support helped prevent the displacement of distal extension RPDs and decreased the pressure on soft tissues.     

老年人可摘局部义齿修复后对基牙牙周状况的影响

目的：研究老年人戴用可摘局部义齿对基牙牙周健康状况的影响。方法：对56例牙列缺失后的老年人行可摘局部义齿修复,3个月、12个月后复查并记录基牙与对侧同名牙的菌斑指数、牙龈指数、探诊出血指数、探诊深度等四项牙周指标。结果：患者戴用可摘局部义齿后基牙的四项牙周指标明显高于对照牙（P〈0．01）;老年患者戴用可摘局部义齿后的3个月内,基牙的牙周指数均明显升高（P〈0．01）,12个月时基牙的牙周状况趋于稳定状态。结论：老年人戴用可摘局部义齿可引起基牙的牙周指数增加。     

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.     

可摘局部义齿重做情况问卷调查

目的：了解可摘局部义齿修复效果、使用年限,分析有关影响因素。方法：对323例重做可摘局部义齿患者进行问卷调查并统计分析。结果：84％以上患者修复效果满意;义齿平均使用年限为6．5年;义齿重做首要原因为又失牙,牙周炎失牙多于龋病,基牙失牙多于非基牙（P〈0．001）;与咀嚼能力有关因素依次为：义齿制作地点、失牙原因、余牙数、义齿颌位、患者年龄;与义齿使用年限有关因素依次为：患者年龄、戴牙习惯、吸烟情况、对颌情况等。结论：多数可摘局部义齿修复效果满意;义齿平均使用年限6．5年;应重视防治牙周炎和龋病,重视基牙保健;提高可摘局部义齿咀嚼能力与使用年限。