Effect of clasp design on retention at different intervals using different abutment materials and in a simulated oral condition.

PURPOSE: The purpose of this study was to compare the retention of circlet (E) clasps and back-action clasps against three abutment surface materials during long-term simulation of attachment and detachment. MATERIAL AND METHODS: Forty-eight test models were constructed by placing premolars (natural abutments or metal dies) inside metal blocks to test different abutment retention surface materials (sound enamel, composite resin, and glass-ceramic; 16 each). The models were duplicated into investment models for construction of circlet (E) and back-action clasps. Removal and insertion cycling of clasps was carried out for 250, 500, 1000, 2000, 4000, 8000, and 16,000 cycles. The retention of each clasp was measured before cycling and after each interval. Data were analyzed using 1-way-ANOVA, 2-way-ANOVA, and Mann-Whitney U tests. RESULTS: No significant differences in retention of either clasp were found between the three abutment material surfaces; however, there was a significant decrease in retention force of the circlet (E) clasp between 1000 and 2000 cycles but not of the back-action clasp. CONCLUSIONS: (1) The back-action clasp maintains its retention force for a longer period than the circlet (E) clasp. (2) Composite resin contouring of teeth provided retention comparable to enamel and a ceramic material.

Treatment outcomes with removable partial dentures: a retrospective analysis.

PURPOSE: This retrospective clinical study aimed to evaluate the long-term outcomes of clasp-retained, metal-framework removable partial dentures (RPDs) and their clasped teeth, the influencing factors on survival, and the type and number of repairs needed during the observation period. MATERIALS AND METHODS: The study is based on a convenience sample of 52 patients who received 65 RPDs with a total of 207 clasped teeth. The mean observation period was 3.11 ± 0.29 years (maximum: 10 years). Patient gender, prosthesis location (maxilla/mandible), number and distribution (Kennedy class) of abutment teeth, and impact of a continuous follow-up program on a favorable outcome probability were analyzed. Statistical analysis was performed using the Kaplan-Meier method (P < .05) in combination with Cox regression analysis. RESULTS: During the observation period, 9.2% of the RPDs ceased to function and 5.8% of the abutment teeth were extracted. Mean RPD survival time was 8.07 ± 0.66 years, with a positive outcome probability of 90% after 5 years. Prosthesis location was the only parameter that significantly (P < .05) impacted this probability. CONCLUSION: Overall, the high survival probability and low extraction rate of the abutment teeth reported in this study indicate that RPDs designed according to hygienic pronciples are clinically successful.

Survey of partial removable dental prosthesis (partial RDP) types in a distinct patient population.

STATEMENT OF PROBLEM: Current demographic information on the number and types of removable partial dentures is lacking in the prosthodontic literature. PURPOSE: This study was designed to investigate patterns of tooth loss in patients receiving removable partial dentures (RPDs) in eastern Wisconsin. MATERIAL AND METHODS: Digital images (1502) of casts at 5 dental laboratories in eastern Wisconsin were collected. Any prescription requesting fabrication of a removable partial denture was photographed twice. The first photograph was made immediately upon arrival at the laboratory, while the second photograph was made immediately before being returned to the prescribing dentist for the first time. A calibrated investigator analyzed all the photographs for Kennedy Classification, type of RPD, major connector, and other details. Data were analyzed with descriptive statistics. Fisher's exact test was used to confirm repeatability. RESULTS: Kennedy Class I was the most common RPD with a frequency of 38.4%. More than 40% of prescriptions had no design input from the dentist. One in 3 RPDs used acrylic resin or flexible frameworks. One in 5 RPDs had no rests. The horseshoe major connector was the most common maxillary major connector, while the lingual plate was the most common in the mandible. CONCLUSIONS: RPDs remain a common prosthodontic treatment in this region. Non-metal RPD frameworks are a common treatment type and rarely include rests. These data indicate a changing partially edentulous patient population and a variable commitment to standard levels of prosthodontic care.

Partial edentulism and removable partial denture design in a dental school population: a survey in Greece.

OBJECTIVES: To investigate the pattern of partial edentulism and the most frequent designs of cobalt-chromium removable partial dentures (RPDs), constructed at the Dental School of Athens, Greece. METHODS AND MATERIALS: Five hundred and fifty-three patients, between 42 and 81 years old, mostly males, treated by undergraduate dental students, were included. The survey was based on visual evaluation of master casts and work authorisation to dental technicians. Aspects examined were: Kennedy Classification, modification areas, major connectors, clasping, placement of rest seats and indirect retention. RESULTS: Kennedy Class I was the most common encountered in the maxilla (50.5%) and in the mandible (70%). The most frequent major connectors were the lingual bar (92.6%) and the U-shaped palatal strap (54%). The most common clasp was the Roach (69.2%) in Class I and Class II. In Class III and IV, the most common was the occlusally approaching clasp (55% and 70%). The most frequent location of the rest was mesial of abutment teeth. On the average, 39.5% of Class I RPDs and 58.6% of Class II RPDs had indirect retainers. CONCLUSION: A combination of the two major philosophies of RPD design (biomechanical and hygienic) was evident in the RPDs examined in our study.

Rotational path removable partial denture: an esthetic alternative.

Missing teeth can be replaced using any of a number of methods. Patients may choose to replace missing teeth with a prosthesis that is either removable, fixed, or retained with implants. When it is necessary to replace anterior or posterior teeth, a properly designed and fabricated rotational path removable partial denture can be both successful and esthetically pleasing to the patient. However, while a patient's functional and esthetic needs can be met successfully, rotational path removable partial dentures can be more demanding for the laboratory technician to fabricate and for the dentist to seat in the mouth. Rotational path removable partial dentures frequently are overlooked as a viable means of treating missing teeth. This article reviews the principles of rotational path removable partial dentures, as well as their categories, advantages, and disadvantages, in the hope that more dentists will consider them when the need arises.

Aesthetic clasp design for removable partial dentures: a literature review.

Removable partial dentures (RPD) are an effective and affordable treatment option for partial edentulism. If the main reason for seeking treatment is the need for improved aesthetics, treatment should be geared towards achieving this goal. This article is the result of a literature study on aesthetic clasp design for the conventional RPD. In this context, the position of the clasp on the tooth, clasp types, clasp material and alternative methods of retention are reviewed. Although published in reputable journals, the authors report that many articles published on this subject are of a descriptive nature and lack scientific evidence. Therefore, clinicians are encouraged to be critical in their interpretation of literature and the application of published information in their clinical practices.

The effects of loading locations and direct retainers on the movements of the abutment tooth and denture base of removable partial dentures.

The purpose of this study was to evaluate the degree and amount of movement of the abutment tooth and denture base influenced by the direct retainer of distal extension removable partial denture and the location of functional loading, then to suggest direct retainer design with minimal adverse effect and with optimum functional loading location for residual tissue. The displacement of the abutment tooth and inclination of the denture base were determined, with 30 N as work load utilizing simulation model and strain gauge system, about two types of direct retainers with mesial or distal rest and nine loading points on denture base. Displacement and inclination was determined with the one-way analysis of variance and Scheffe's multiple test was performed. The results revealed that type of direct retainer influenced on the magnitude rather than direction of the abutment tooth displacement. The distal displacement of abutment tooth was significantly less in Type M clasp (with mesial rest and connection) than in Type D clasp (with distal rest and connection) (p<0.05). The location of loading points influenced both of the magnitude and direction of the abutment tooth and denture base movement. Posterior and lingual loading resulted in significantly distal displacement of abutment tooth (p < 0.05).

Análise comparativa da capacidade retentiva de grampos tipo "T" usados em prótese parcial removível em armaçöes de titânio e cobalto-cromo / Comparative analysis of clasps type \"T\" retentive capacity used in removable partial denture in titanium and cobalt-cromium frameworks

Estudou-se a capacidade retentiva de grampos tipo "T" em prótese parcial removível (PPR) comparando-se armaçöes confeccionadas em liga de Co-Cr e Ti. Foram utilizados dez corpos-de-prova com cada tipo de liga que foram levados a um dispositivo para simular a inserçäo e remoçäo de armaçöes de PPR, como acontece clinicamente em pacientes, por períodos de 6 meses, 1, 2, 3, 4 e 5 anos. Depois de cada período de simulaçäo, estes corpos-de-prova eram levados a uma máquina de traçäo para se medir a quantidade de retençäo ainda presente em cada armaçäo, respectivamente, em ambiente seco e umedecido com saliva artificial; depois disso, eram pesados em uma balança de precisçao para se observar prováveis perdas de peso, tanto das armaçöes quanto dos dentes naturais dos corpos-de-prova. A análise estatística dos resulatdos nos permitiu concluir que näo houve diferença estatisticamente significante de retençäo entre as armaçöes confeccionadas em Co-Cr e Ti, nos períodos de tempo simulados, tanto em ambiente seco quanto umedecido com saliva artificial

Avaliaçäo da capacidade retentiva de grampos do tipo T e I usados em prótese parcail removível sobre superfícies de esmalte, amálgama e resina composta / Evaluation of tensile bond strength of Tand I type clasps used in removable partial prosthesis for composite resin, amalgam and enamel surfaces

Para a realizaçäo deste trabalho foram utilizados 60 dentes pré-molares recém-extraídos para fins ortodônticos fixados em bases metálicas a base de Co-Cr de forma trapezoidal, especialmente confeccionadas para adaptarem-se a máquina de costura Elgin. Os dentes foram divididos em 6 grupos) Grupo 1 - Grampo "T"em superfície de esmalte, Grupo 2 - Grampo "I" em superfície de esmalte, Grupo 3 - Grampo "T" em superfície de amálgama, Grupo 4 - Grampo "I" em superfície de amálgama, Grupo 5 - Grampo "T" em superfície de resina composta e, Grupo 6 - Grampo "I" em superfície de resina composta), para avaliar a resistência ao deslocamento dos grampos "T" e "I" sobre as supefícies de esmalte, amálgama e resina composta. Os corpos de prova receberam os testes de remoçäo e inserçäo numa máquina de costura Elgin adaptada para esta finalidade. Com um conta-giros foi feita a leitura aos ciclos de 6 meses, 1 ano, 2 anos, 3 anos, 4 anos, 5 anos. Os testes de resistência ao deslocamento axial dos grampos "T" e "I" pós-traçäo foram realizados numa máquina de Ensaio Universal Kratos a cada intervalo de tempo previamente estabelecido. Inicialmente e após cada período dos testes, os corpos de prova juntamente com os grampos foram submetidos à pesagem com o auxílio de uma balança de precisäo...

Análise comparativa da capacidade retentiva de grampos tipo T usados em prótese parcial removível em armaçöes de titânio e cobalto-cromo / Comparative analysis of retentive capacity of clasps type T used in removable partial prosthesis in frames made in titanium and cobalt-chromium metallic alloys

Estudou-se a capacidade retentiva de grampos tipo "T" em prótese parcial removível (PPR) comparando-se armaçöes confeccionadas em liga de Co-Cr e Ti. Foram utilizados dez corpos de prova com cada tipo de liga que foram levados a um dispositivo desenvolvido para simular a inserçäo e remoçäo de armaçöes de PPR, como acontece clinicamente em pacientes, por períodos de 6 meses, 1, 2, 3, 4 e 5 anos. Depois de cada período de simulaçäo, estes corpos de prova eram levados a uma máquina de traçäo para se medir a quantidade de retençäo ainda presente em cada armaçäo, respectivamente em ambiente seco e umedecido com saliva artificial; depois disso, eram pesados em uma balança de precisäo para se observar prováveis perdas de peso, tanto das armaçöes quanto dos dentes naturais dos corpos de prova. A análise estatística dos resultados nos permitiu concluir que näo houve diferença estatisticamente significante de retençäo entre as armaçöes confeccionadas em Ti e Co-Cr, nos períodos de tempo simulados, tanto em ambiente seco quanto em umedecido com saliva artificial, e que foi estatisticamente significante a perda de peso tanto das armaçöes quanto dos dentes naturais dos corpos de prova da utilizaçäo do Ti e do Co-Cr nos referidos tempos

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 have changed in the past 30 years.