Is scanning under rubber dam isolation a feasible approach for the execution of indirect restorations? / O escaneamento sob isolamento absoluto é uma técnica viável para execução de restaurações indiretas?

Objective: The aim of the study was to report the aplicability of intraoral scanning while rubber dam isolation is in place. Material and Methods: Female patient, 50 years old, required restorative procedures on teeth 35 and 37. An intraoral scan was initially performed on both arches. Isolation was carried out from 33 to 37, tooth preparation and immediate dentin sealing were carried out. A new scan with the rubber dam in place was performed and a CAD/CAM lithium disilicate hybrid block was digitally designed, milled, crystallized and cemented under the tooth surface with the rubber dam still in position. After completing this stage, the rubber dam was removed, the occlusion was verified, presenting excellent aesthetic and functional results. Results: The absolute isolation process used in the present study works as an excellent device for gingival retraction. Conclusion: The absolute isolation can be recommended in clinical activities of intraoral scanning favoring the quality of the final result of treatments (AU)

Objetivo: O objetivo do estudo foi relatar a aplicabilidade do escaneamento intraoral sob isolamento absoluto. Material e Métodos: Paciente do sexo feminino, 50 anos, necessitou de procedimentos restauradores nos dentes 35 e 37. Uma varredura intraoral foi inicialmente realizada em ambos os arcos. O isolamento absoluto foi feito de 33 a 37, permitindo a realização do preparo dentário e selamento imediato da dentina. Um novo escaneamento com o dique de borracha colocado foi realizado e um bloco híbrido de dissilicato de lítio CAD/CAM foi projetado digitalmente, fresado, cristalizado e cimentado sob a superfície dentária ainda com o dique de borracha em posição. Após a finalização dessa etapa, o dique de borracha foi removido, a oclusão foi verificada apresentando ótimos resultados estéticos e funcionais. Resultados: O isolamento absoluto utilizado no presente estudo funciona como um excelente dispositivo para retração gengival. Conclusão: O isolamento absoluto pode ser recomendado em atividades clínicas de escaneamento intraoral favorecendo a qualidade do resultado final dos tratamentos (AU)

Comparación de prótesis removibles parciales y totales entregadas según sus características clínicas en el servicio de odontología del hospital nacional de geriatría y gerontología, en el período de tiempo comprendido del 1 de enero 2005 al 31 de diciembre del 2008 / Comparison of partial and total removable prosthesis delivered according to their clinical characteristics in the dentistry service of the national hospital of geriatry and gerontology, in the period under january 1 of 2005 to december 31 of 2008

RESUMEN Objetivo: Comparar la cantidad y características de las prótesis dentales removibles parciales y totales, en el servicio de odontología del Hospital Nacional de Geriatría y Gerontología, en el periodo de tiempo comprendido del 1 de enero 2005 al 31 de diciembre 2008, equivalentes a 326 expedientes. Se tomó la base de datos del servicio de odontología de consulta externa especializada de los pacientes atendidos de los años 2005 al 2008, en los cuales se entregaron un total de 2786 prótesis dentales removibles. Materiales y métodos: Con base en el dato anterior se seleccionó la muestra no aleatoria a conveniencia hasta alcanzar el tamaño de 599 prótesis entregadas, examinando 326 expedientes del periodo de enero del 2005 a diciembre del 2008, con un nivel de confianza de 99% y un error de muestreo de 0.0466. La recolección de datos se realizó por medio del programa Microsoft Excel donde se utilizó una tabla en la que se anotó el número de expediente, fecha de inicio y conclusión de prótesis, tipo de prótesis, cantidad y color de prótesis, edad, género y domicilio del paciente por distrito, cantón y provincia. El procesamiento se realizó por medio de estadística descriptiva utilizando cuadros y gráficos. Resultados: Se determinó que el mayor porcentaje de rango de edad de personas que solicitaron prótesis removibles fue de 62 a 65 años, independiente si eran prótesis totales o parciales, los pacientes que requirieron dos prótesis fueron 273 de 326, en su mayoría los pacientes solicitaron prótesis totales para un total de 372 de 599 prótesis entregadas. De la guía de color utilizada en el HRBC los colores más requeridos fueron los tonos claros blanco amarillentos que corresponde al número 62 y 65; de los expedientes analizados la mayoría de los pacientes residían en San José con un total de 200 pacientes. Se concluye que el mayor porcentaje de edentulismo que se presento es el edentulismo total con un 62%, la prótesis más utilizada es la prótesis total superior removible y en su mayoría los pacientes requieren dos prótesis, con respecto al color no es concluyente para este estudio debido a los datos no disponibles en los expedientes analizados.

ABSTRACT Objective: Compare the quantity and characteristics of partial and total removable dental prostheses, in the dentistry service of the National Hospital of Geriatrics and Gerontology, in the period from January 1, 2005 to December 31, 2008. The database of the specialized outpatient dentistry service of the patients treated from 2005 to 2008 was taken, in which a total of 2786 removable dentures were delivered. Materials and methods: Based on the previous data, the non-random sample was selected for convenience until reaching the size of 599 protheses of 326 files, with a confidence level of 99% and a sampling error of 0.0466. Data collection was carried out through the Microsoft Excel program where a table was used in which the file number, date of start and conclusion of the prosthesis, type of prosthesis, amount and color of prosthesis, age, gender and address were used of the patient by district, canton and province. The processing was carried out by means of descriptive statistics using tables and graphs. Results: It was determined that the highest percentage of the age range of people who requested removable prostheses was 62 to 65 years, the patients that required two prostheses were 273 of 326. In their majority, the patients requested total prostheses for a total of 372 of 599 prostheses delivered. Of the color guide used in the HRBC, the most requested colors were the light yellowish-white tones corresponding to the number 62 and 65; of the files analyzed, most of the patients resided in San José with a total of 200 patients. Conclusion: It is concluded that the highest percentage of edentulism that is presented is total edentulism with 62%, the most commonly used prosthesis is the removable upper total prosthesis and for the most part patients require two prostheses, with respect to color it is inconclusive for this study due to data not available in the analyzed files.

The effect of different framework's material on strain induced in distal abutment in mandibular Kennedy's class II: an in-vitro study / O efeito de diferentes materiais de estrutura na deformação induzida na distal do pilar da classe II de Kennedy mandibular: um estudo in vitro

Objective: This study aims to compare the strain induced in the supporting structures of unilateral mandibular removable partial denture frameworks retained by extra-coronal attachments fabricated with three different materials. Material and Methods: Three mandibular class II digitally designed and printed acrylic models with detachable abutments were used to fabricate three removable partial denture framework with extra coronal attachments from three different materials. A total of 33 models were prepared for strain testing (n=11). Models were divided into three groups according to framework's material: porcelain fused to cobalt chromium (PFM), polyetherketoneketone (PEKK) and polyetheretherketone (PEEK) group. Unilateral load of 60 N was applied in the three groups and strains were measured around the main abutment and saddle area using strain gauge. Results: Statistical analysis was performed using Shapiro-Wilk's test and by checking data distribution. Data were found to be non-parametric and were analysed using Kruskal-Wallis test followed by Dunn's post hoc test with Bonferroni correction. PFM group showed significantly the highest strain values around abutment, slot 1 (1mm distal to the socket of the last abutment) and slot 2 (1 cm away from slot 1) respectively (843.00±23.08, 91.00±6.52 and 1274.00±65.71) than the other tested groups (p<0.05) at same tested sites respectively followed by PEKK group (384.00±37.48, 81.00±2.24 and 135.00±0.00) and PEEK group (29.00±4.18, 63.00±4.47 and 52.00±5.70). Conclusions: PEEK and PEKK for partial denture framework with extra coronal attachments are adequate alternative to PFM due to their good mechanical response applying less strain on supportive structures in free-end cases. PEEK induces lower strain magnitude on the supporting structures when compared to PEKK. (AU)

Objetivo: Este estudo tem como objetivo comparar a tensão induzida nas estruturas de suporte de estruturas de próteses parciais removíveis mandibulares unilateraisretidas por encaixes extracoronários fabricados com três materiais diferentes. Material e Métodos: Três modelos mandibulares de classe II digitalmente projetados e impressos em acrílico com pilares destacáveis foram usados para fabricar três estruturas de próteses parciais removíveis com encaixes extracoronários de três materiais diferentes. Um total de 33 modelos foram preparados para testes de deformação (n=11). Os modelos foram divididos em três grupos de acordo com o material da estrutura: porcelana fundida com cobalto-cromo (PFM), poliétercetonacetona (PEKK) e polieteretercetona (PEEK). Carga unilateral de 60 N foi aplicada nos três grupos e as deformações foram medidas em torno do pilar principal e área de sela usando medido de tensão. Resultados: A análise estatística foi realizada por meio do teste de Shapiro-Wilk e com a verificação da distribuição dos dados. Os dados mostraram-se não paramétricos e foram analisados pelo teste de Kruskal-Wallis seguido pelo de Dunn com correção de Bonferroni. O grupo PFM mostrou significativamente os maiores valores de tensão ao redor do pilar, slot 1 (1mm distal do último pilar) e slot 2 (1 cm de distância do slot 1) respectivamente (843,00±23,08, 91,00±6,52 e 1274,00±65,71) do que os outros grupos testados (p<0,05) nos mesmos locais testados, respectivamente, seguido pelo grupo PEKK (384,00±37,48, 81,00±2,24 e 135,00±0,00) e grupo PEEK (29,00±4,18, 63,00±4,47 e 52,00±5,70). Conclusão: PEEK e PEKK para estrutura de prótese parcial com encaixes extracoronários são alternativas adequadas ao PFM devido à sua boa resposta mecânica aplicando menos tensão nas estruturas de suporte em casos de extremidade livre. O PEEK induz menor magnitude de deformação nas estruturas de suporte quando comparado ao PEKK (AU)

Risk Factors of Composite Attachment Loss in Orthodontic Patients during Orthodontic Clear Aligner Therapy: A Prospective Study.

BACKGROUND: The composite attachment loss during orthodontic clear aligner therapy is an adverse event that commonly happens in our daily practice. However, there is a lack of related statistical analysis and studies analyzing the related risk factors. Therefore, the aim of this study is to assess the incidence of attachment loss during orthodontic clear aligner therapy and to identify rick factors that may predict such event. MATERIALS AND METHODS: The demographics and clinical variables of 94 patients undergoing clear aligner therapy (27 males and 67 females; average age: 27.60 ± 0.86 years) were recorded. Both patient-related and tooth-related attachment loss was recorded. The chi-squared test and logistic regressive analysis were applied to identify the potential risk factors. SPSS for Mac (version 23.0, IBM, USA) was used for statistical analyses. P < 0.05 was considered statistically significant. RESULTS: Our study suggested that the risk factors for attachment loss include frequent aligner removal (≥ 5 times a day) (losing rate = 60.0%, P = 0.005), aligner wear time less than 18 hours a day (losing rate = 50.8%, P = 0.014), eating without aligners inserted (losing rate = 47.9%, P = 0.034), utilizing aligner tray seaters (losing rate = 48.2%, P = 0.006), and unilateral mastication (losing rate = 52.1%, P = 0.002). The multivariable logistic regression analysis indicates that aligner wear time less than 18 hours a day (P = 0.020, B = 0.925), using aligner tray seaters (P = 0.007, B = 1.168), and unilateral mastication (P = 0.034, B = -0.458) were considered independent factors that can predict the composite attachment loss in orthodontic clear aligner therapy. CONCLUSION: Wearing aligner less than 18 hours a day, using aligner tray seaters, and unilateral mastication may contribute to increased incidence of composite attachment loss during orthodontic clear aligner therapy.

Locator® versus ceramic/electroplated double-crown attachments: a prospective study on the intraindividual comparison of implant-supported mandibular prostheses.

OBJECTIVES: Implant-supported overdentures are an established dental treatment mode. The aim of this prospective study was and interindividual comparison of patient satisfaction with restorations retained by a prefabricated and thus inexpensive attachment system (Locator®) or with a technologically complex and thus expensive attachment system (ceramic/electroplated double crowns) with similar retentive performance. MATERIALS AND METHODS: Twelve patients received a Locator and a double-crown prosthesis in a crossover study for test periods of 3 months each. The main target parameter was the patient's final decision in favor of one of the two prosthesis types. RESULTS: After completing both test phases, seven patients opted for the Locator prosthesis and five patients opted for the double-crown prosthesis. CONCLUSION: Given the predominant lack of statistically significant differences, the two types of prostheses can be described as equivalent. A recommendation in favor of the Locator prosthesis can be motivated by its lower cost. CLINICAL RELEVANCE: The results of the study show that the more cost-effective variant was comparable to the more expensive double-crown prosthesis under the conditions prevailing in the study. Depending on the indication, this may influence the decision-making process in daily clinical practice and support the clinician's patient information and consultation efforts.

Retention force and deformation of an innovative attachment model for mini-implant-retained overdentures.

STATEMENT OF PROBLEM: The gradual loss of retention and the need for periodic replacement of attachment-system components are the most frequent complications in implant-supported overdentures. PURPOSE: The purpose of this in vitro study was to develop a new attachment system for overdentures with polymeric materials and compare its retention and deformation with a conventional O-ring attachment system. MATERIAL AND METHODS: A matrix with 2 mini-implants with ball abutments was used to simulate the mandibular border during a fatigue resistance test. A total of 60 polyacetal (n=20), polytetrafluoroethylene (n=20), and conventional O-ring (n=20) attachments were captured in pairs with acrylic resin and subjected to 3625 insertion and removal cycles, simulating 30 months of overdenture use. The internal and external deformations of the attachments were assessed using an optical stereomicroscope. One-way ANOVA and the Tukey honestly significant difference tests were used for statistical evaluation (α=.05). RESULTS: The polyacetal attachment system showed the highest retention (P<.001), followed by the O-ring and polytetrafluoroethylene attachments. The O-ring attachments exhibited the lowest deformation (P<.001), and the polyacetal attachments had the highest internal deformation (P<.001). CONCLUSIONS: The newly developed polyacetal attachment model increased the retention of mini-implant-retained overdentures, and despite the deformation experienced, the retention period appears to be better than that of conventional systems.

Treatment Outcomes Based on Patient's Oral Health Related Quality of Life (OHRQoL) after Receiving Conventional Clasp or Precision Attachment Removable Partial Dentures in Distal Extension Cases: A Randomized Controlled Clinical Trial / Resultado do tratamento com Prótese Parcial Removível convencional ou com encaixe de precisão, em casos de extremidade livre, baseado no índice de qualidade de vida relacionado á saúde bucal (OHROoL): ensaio clínico controlado e randomizado

Objetivos: Comparar o efeito de duas opções de tratamento (próteses parciais removíveis retidas por encaixe de precisão (PA-RPD) ou grampos (C-RPD) em casos de classe I inferiores de Kennedy em relação à qualidade de vida relacionada à saúde bucal (OHRQoL) e a força de mordida. Material e Métodos: O estudo incluiu 32 pacientes parcialmente desdentados, dos quais 16 receberam PA-RPD (OT Cap Attachment) e 16 pacientes receberam C-RPD. Todos os pacientes de ambos os grupos foram solicitados a preencher o questionário OHRQoL após 1 semana (linha de base), 3 meses, 6 meses e 12 meses após a inserção da prótese. A força de mordida foi medida usando o i-load Star Sensor uma semana, 3 meses, 6 meses e 1 ano após a inserção parcial da prótese em todos os pacientes dos dois grupos. A análise estatística compreendeu o teste U de Mann Whitney, teste de Friedman, teste de Dunn e teste do qui-quadrado. Resultados: Os resultados da OHRQoL revelaram que, no período basal, 3 meses e 6 meses, o PA-RPD apresentou um escore total médio mais baixo estatisticamente significativo do OHIP-14 do que o C-RPD. No entanto, após 12 meses, não houve diferença estatisticamente significante entre os escores totais do OHIP-14 nos dois grupos. Em relação à força de mordida, não houve diferença estatisticamente significante entre os dois grupos. Conclusão: Dentro das limitações deste estudo, concluiu-se que a OHRQoL do PARPD e do C-RPD era comparável após 12 meses. Da mesma forma, a força de mordida foi a mesma para as duas opções de tratamento.(AU)

Objective: To compare the effect of two treatment options in mandibular Kennedy class I cases regarding oral health related quality of life (OHRQoL) and the biting force, removable partial dentures retained by either precision attachment (PA-RPD) or clasps (C-RPD). Material and Methods: The study included 32 partially edentulous patients which 16 patients received PA-RPD (OT Cap Attachment) and 16 patients received C-RPD. All the patients in both groups were asked to fill the OHRQoL questionnaire after 1 week (baseline), 3 months, 6 months and 12 months after prosthesis insertion. Biting force was measured using the i-load Star Sensor one week, 3 months, 6 months and 1 year after partial denture insertion for all patients in both groups. Statistical analysis comprised Mann Whitney U test, Friedman's test, Dunn's test and Chisquare test. Results: The results of OHRQoL revealed that at the baseline, 3 months and 6 months the PA-RPD showed statistically significant lower mean total OHIP- 14 score than the C-RPD. However, after 12 Monthes , there was no statistically significant difference between total OHIP-14 scores in the two groups. Concerning the biting force there was no statistically significant difference between the two groups. Conclusion: Within the limitations of this study it was concluded that the OHRQoL of both the PA-RPD and the C-RPD was comparable after 12 months. Similarly the biting force was the same for both treatment options. (AU)

Retention Force and Wear Characteristics of three Attachment Systems after Dislodging Cycles.

Several attachment systems for mandibular implant-supported overdentures are currently available and studies are required to understand their mechanical properties. The objective of this study was to evaluate the retention force and wear characteristics of three attachment systems in a simulation of the cyclic dislodging of implant-supported overdentures. Thirty samples were fabricated and divided into 3 groups: 1-O-ring; 2-Mini Ball; and 3-Equator. A mechanical fatigue test was applied to the specimens using a servo-hydraulic universal testing machine performing 5500 insertion/removal cycles (f=0.8 Hz), immersed in artificial saliva. Retention force values ​​were obtained before and after 1500, 3000, and 5500 cycles using a speed of 1 mm/min and a load cell of 1 kN. One specimen from each group was randomly selected and analyzed by scanning electron microscopy. Two-way repeated measures ANOVA and the Bonferroni post hoc test were used for statistical analyses (α=0.05). The O-ring system remained stable during all periods tested and exhibited significantly lower retention force values than the Mini Ball and Equator systems. The Mini Ball system exhibited a significant increase in retention force after the mechanical test (baseline=21.04±3.29N; 5500 cycles=24.01±3.30N).The Equator system exhibited a significant decrease in retention force after each period tested, but the values were higher than the other systems. The type of attachment was found to influence retention force in different ways after mechanical tests. The Equator system exhibited the highest retention force values. The Mini Ball and Equator matrices produced deformation and wear on the surfaces without breakage of the polyamide rings.

Implant-retained overdenture and o-ring attachments ­ case report / Overdenture retida por implantes e encaixes do tipo o'ring ­ relato de caso

The increase in life expectancy occurred along an increase in the demand of edentulous patients for a type of rehabilitation that provides higher masticatory efficiency. Thus, implant overdentures using the ball/o-ring and bar-clip attachment systems represent a muco-supported and implant-retained prosthetic type that allows greater security, stability, and aesthetics, besides presenting a lower cost and easier hygiene. The present study aims to report a clinical case of overdenture with the o-ring retention system. In this case, the patient complained of difficulties during mastication due to instability of the mandibular complete denture, sensitivity from the superficialization of the mental foramina, dissatisfaction with aesthetics, and successive dislocations of the mandibular condyle. After clinical and radiographic evaluation, the treatment proposed was the installation of two osseointegrated implants between the mental foramina and the o-ring attachment overdenture. This prosthetic rehabilitation presents a successful clinical follow-up of 24 months, confirming the effectiveness of the treatment applied. The patient was satisfied because the implant-retained prosthesis provided benefits related to aesthetics, comfort, phonation, and mastication. It is noted that the rehabilitation performed has solved the patient's initial complaints. After the clinical case and literature review, it is concluded that overdentures using the o-ring retention system are viable alternatives and provide adequate function and aesthetics, presenting integration with the stomatognathic system.

Com o aumento da expectativa de vida, houve também o aumento da procura dos pacientes edêntulos por uma forma reabilitadora que lhes proporcione maior eficiência mastigatória. Sendo assim, as sobredentaduras sobre implantes utilizando sistemas de encaixe bola/o'ring e barra-clip representam modalidade protética mucossuportada e implantorretida que possibilita maior segurança, estabilidade e estética, além de apresentarem menor custo e facilidade para higienização. O presente trabalho tem por objetivo relatar um caso clínico de overdenture que utiliza o sistema de retenção o'ring. Neste caso, a paciente queixava-se de dificuldades durante a mastigação devido à instabilidade da prótese total inferior, sensibilidade pela superficialização dos forames mentuais, insatisfação com a estética, além de sucessivas luxações do côndilo mandibular. Após avaliação clínica e radiográfica, o tratamento proposto foi a instalação de dois implantes osseointegráveis entre os forames mentuais e overdenture com encaixes do tipo o'ring. A reabilitação protética em questão apresenta um acompanhamento clínico bem sucedido de 24 meses, comprovando a eficácia do tratamento instituído. A paciente demonstrou estar satisfeita, pois a prótese implanto-retida possibilitou benefícios relacionados à estética, conforto, fonação e mastigação. Nota-se que a reabilitação realizada atendeu às queixas iniciais da paciente. Após a realização do caso clínico e revisão de literatura, conclui-se que overdentures que utilizam o sistema de retenção o'ring são alternativas viáveis e que promovem função e estética adequadas, integrando-se ao sistema estomatognático.

Retention force and wear characteristics of three attachment systems after dislodging cycles

Abstract Several attachment systems for mandibular implant-supported overdentures are currently available and studies are required to understand their mechanical properties. The objective of this study was to evaluate the retention force and wear characteristics of three attachment systems in a simulation of the cyclic dislodging of implant-supported overdentures. Thirty samples were fabricated and divided into 3 groups: 1-O-ring; 2-Mini Ball; and 3-Equator. A mechanical fatigue test was applied to the specimens using a servo-hydraulic universal testing machine performing 5500 insertion/removal cycles (f=0.8 Hz), immersed in artificial saliva. Retention force values ​​were obtained before and after 1500, 3000, and 5500 cycles using a speed of 1 mm/min and a load cell of 1 kN. One specimen from each group was randomly selected and analyzed by scanning electron microscopy. Two-way repeated measures ANOVA and the Bonferroni post hoc test were used for statistical analyses (α=0.05). The O-ring system remained stable during all periods tested and exhibited significantly lower retention force values than the Mini Ball and Equator systems. The Mini Ball system exhibited a significant increase in retention force after the mechanical test (baseline=21.04±3.29N; 5500 cycles=24.01±3.30N).The Equator system exhibited a significant decrease in retention force after each period tested, but the values were higher than the other systems. The type of attachment was found to influence retention force in different ways after mechanical tests. The Equator system exhibited the highest retention force values. The Mini Ball and Equator matrices produced deformation and wear on the surfaces without breakage of the polyamide rings.

Resumo Vários sistemas de encaixe para sobredentaduras mandibulares implantossuportadas estão atualmente disponíveis e estudos são necessários para entender as suas propriedades mecânicas. O objetivo deste estudo foi avaliar a força de retenção e as características de desgaste de três sistemas de encaixe por meio de uma simulação de deslocamento cíclico de sobredentaduras implantossuportadas. Trinta amostras foram fabricadas e divididas em 3 grupos: 1-O-ring; 2-Mini Ball; e 3-Equador. Um teste de fadiga mecânica foi aplicado aos espécimes utilizando uma máquina de teste universal servo-hidráulica com 5500 ciclos de inserção/remoção (f = 0,8 Hz), imersos em saliva artificial. Os valores da força de retenção foram obtidos antes e após 1500, 3000 e 5500 ciclos utilizando uma velocidade de 1 mm/min e uma célula de carga de 1 kN. Um espécime de cada grupo foi selecionado aleatoriamente e analisado por microscopia eletrônica de varredura. O teste de Análise de Variância a dois fatores para medidas repetidas e o teste de comparações múltiplas de Bonferroni foram utilizados para análises estatísticas (α = 0,05). O sistema de O-ring permaneceu estável durante todos os períodos testados e apresentou valores de força de retenção significativamente menores do que os sistemas Mini Ball e Equator. O sistema Mini Ball apresentou um aumento significativo na força de retenção após o teste mecânico (controle = 21,04 ± 3,29N; 5500 ciclos = 24,01 ± 3,30N). O sistema Equator apresentou uma diminuição significativa na força de retenção após cada período testado, mas os valores eram maiores do que os outros sistemas. O tipo de sistema de encaixe influenciou na força de retenção de diferentes maneiras após testes mecânicos. O sistema do Equador exibiu os maiores valores de força de retenção. As matrizes dos sistemas Mini Ball e Equator produziram deformação e desgaste nas superfícies sem ruptura dos anéis de poliamida.

The In Vitro comparison of the retention of an implant-supported stud attachment locator and straumann ball attachment at different angulations.

AIM: In this study, we investigated the retention of two attachment types, Straumann ball (SB) and Straumann Locator® (SL) attachments, on different implant angulations and identified the most appropriate treatment type or attachment system for each angulation. MATERIALS AND METHODS: The attachments placed on angulation of 0°-, 10°-, and 20° implants were subjected to 1440 vertical insertion-separation cycles. The retention values of the attachments after 0, 720, and 1440 cycles were measured using the Instron machine. In addition, scanning electron microscopy images of the attachments and abutments were obtained before and after the insertion-separation process. RESULTS: There was a significant difference between the SB and SL attachments that were placed on 0° after 1440 cycles (P < 0.05) and between 20° SB and 20° SL attachments after 720 and 1440 cycles (P < 0.05) in terms of retention. No significant difference was observed between 20° SB and 20° SL attachments at 0 cycles (P > 0.05). CONCLUSIONS: In implants with a 20° angle, retention of stud attachments decreased more than ball attachments after use. Thus, the total angle between the implants should not be <20° if long-term retention is desired when using stud attachments. For implants with angles >20°, 6-month patient controls are required to control retention of attachments by considering factors in the mouth with the two tested attachment systems.

Splinted and unsplinted overdenture attachment systems: A systematic review and meta-analysis.

Splinted and unsplinted overdenture attachment systems have unique advantages and disadvantages. The aim of the present systematic review was to determine the influence of splinted and unsplinted overdenture attachment systems on the marginal bone loss, prosthetic complications and implant survival rate. PubMed/MEDLINE, Scopus and Cochrane databases were searched for articles published up to October 2017, using the following search terms: "overdenture AND attachment OR overdenture AND bar OR overdenture splinted." The PICO question "Do splinted overdenture attachment systems promote better clinical results in comparison to unsplinted systems?" was evaluated. Eligible studies included randomized controlled clinical trials, prospective studies with at least 10 participants and a minimum follow-up of 6 months, and studies published in English that compared splinted and unsplinted attachment systems within the same study. The 95% confidence interval (CI) was considered for all outcomes analysed. After completion of the different steps in the article selection process, nine articles were included in the qualitative and quantitative analyses. A total of 984 implants were placed in 380 patients (mean age: 62.8 years). The meta-analysis demonstrated no statistically significant differences between splinted and unsplinted attachment systems with regard to marginal bone loss (P = .39; MD: -0.11; 95% CI: -0.37 to 0.14), complications (P = .31; RR: 1.26; CI: 0.80-1.99) and implant survival rate (P = .14; RR: 0.37% CI: 0.10-1.36). In addition, splinted and unsplinted overdenture attachment systems achieved similar results with regard to marginal bone loss, prosthetic complications and implant survival rate.

Sistemas de encaixe em prótese removível ­ revisão de literatura / Association of attachments in removable prosthesis ­ literature review

A reabilitação oral de pacientes parcialmente dentados é versátil e pode ser realizada a partir de várias opções de tratamentos. Os sistemas de encaixes em Próteses Parciais Removíveis (PPR) são opções clínicas disponíveis idealizadas a fim de melhorar as limitações estéticas e funcionais das PPRs. O objetivo deste estudo foi descrever sobre os sistemas de encaixes em prótese parcial removível, elencando suas principais indicações, contraindicações, vantagens e desvantagens a partir de uma revisão de literatura. A revisão foi realizada utilizando-se a base de dados PubMed, SciELO e Lilacs para identificar todos os artigos publicados em português, inglês e espanhol acerca do tema abordado, sendo selecionados aqueles relatos de caso único ou série de casos. As palavras-chave utilizadas foram: "Prótese parcial removível", "Encaixe de precisão de dentadura", "Prótese dentária". A partir das indicações, contraindicações, vantagens e desvantagens do tratamento reabilitador com próteses parciais com sistemas de encaixe, entende-se que com um planejamento clínico e laboratorial adequado, essa opção de tratamento pode proporcionar um excelente resultado para os pacientes parcialmente edêntulos.

Oral rehabilitation for partially edentulous patient is carried out on various treatment options. The attachment systems (clasps) for Removable Partial Dentures (RPD) are available clinical choices idealized to improve the aesthetic and functional limitations of the RPDs. This study aimed at describing the attachment systems of removable partial denture, highlighting their main indications, contraindications, advantages and disadvantages from a literature review. The literature review was carried out using the PubMed, SciELO and Lilacs database to identify all the articles published in Portuguese, English and Spanish languages about the topic, selecting single case and case series report. The key words used were: "Denture, partial, removable", "Denture Precision Attachment", "Dental Prosthesis." Considering the indications, contraindications, advantages and disadvantages of the rehabilitation treatment with partial dentures with attachment system, when performed following an adequate clinical and laboratory planning, this treatment option can provide an excellent result for partially edentulous patient.

Novel Fabrication Technique for Root-supported Overdentures: A Case Report / Técnica de fabricación novedosa para sobredentaduras apoyadas en la raíz: un reporte de caso

ABSTRACT Tooth and bone preservation is essential to support dentures, especially for elderly patients. Retaining the existing teeth and roots for an overdenture postpones edentulism, and this is a convenient alternative to complete dentures and extraction of teeth. Root-supported overdentures attach to the roots with precision attachments. The fit of the attachment of both the denture and the roots or implants is very important for overdentures. The combination of the attachments increases the retention and stability of attachment-retained overdentures. This technique describes an alternative procedure to fabricate root-supported overdentures with combined locator and casted telescopic attachments.

RESUMEN La preservación de los dientes y los huesos es esencial para apoyar las dentaduras postizas, especialmente para pacientes de edad avanzada. Retener los dientes y raíces existentes para una sobredentadura aplaza el edentulismo, y constituye una alternativa conveniente para completar las dentaduras postizas y la extracción de dientes. Las sobredentaduras apoyadas en la raíz se unen a las raíces con aditamentos de precisión. El ajuste del aditamento tanto de la dentadura como de las raíces o implantes es muy importante para las sobredentaduras. La combinación de los aditamentos aumenta la retención y la estabilidad de las sobredentaduras retenidas por aditamento. Esta técnica describe un procedimiento alternativo para fabricar sobredentaduras ancladas en la raíz con un localizador combinado y aditamentos telescópicos fundidos.

Comparison of digital surface displacements of maxillary dentures based on noninvasive anatomic landmarks.

STATEMENT OF PROBLEM: Artificial markers called fiducials are commonly used to orient digitized surfaces for analysis. However, when these markers are tangible and placed in the region of interest, they may alter surface topography and influence data analysis. PURPOSE: The purpose of this in vitro study was to apply a modified digital surface fitting method based on anatomic landmarks to evaluate denture accuracy and to use 2 different denture processing techniques to evaluate the method. The goal was to noninvasively measure and describe any surface differences in denture processing techniques at the intaglio and denture tooth levels. MATERIAL AND METHODS: Twenty standardized maxillary complete dentures were waxed on standardized edentulous casts and processed by using acrylic resin compression (COM, n=10) and injection molding (INJ, n=10) methods. Digital scans were recorded of the anatomic surface of the cast, the intaglio and cameo surfaces of the acrylic resin dentures, and the cameo surface of the wax dentures. Three anatomic fiducials were identified on denture intaglio and cast scans and 4 on the cameo surfaces of waxed and acrylic resin denture scans. These fiducials were then used to digitally align the anatomic with the processed intaglio surfaces and the waxed with the processed cameo surfaces. Surface displacements were compared among processed dentures expressed at specific points (9 tissue landmarks and 8 tooth landmarks). The accuracy of surface displacements was assessed by changes in the number and location of anatomic fiducials. The scanning precision and the intraobserver repeatability in the selection of dental landmarks were also determined. For each landmark, the spatial (x, y, and z) mean differences between the 2 processing techniques were calculated for the intaglio and the cameo surfaces and presented on each orthogonal plane. Statistical nonparametric comparison of these means was analyzed with the Mann-Whitney U test (α=.05). Benjamini-Hochberg corrections for multiple comparisons were used. RESULTS: Changing the number and the location of anatomic landmarks had a small effect on the precision of the surface fitting. Repeated scans yielded high precision levels. In contrast, intraobserver repeatability had a larger error. In general, injection-molded dentures showed less displacement after polymerization than did the compression-molded ones. These differences were more substantial at the denture tooth level than on the intaglio surfaces. CONCLUSIONS: Anatomic noninvasive fiducials chosen at distinct locations of maxillary edentulous areas seem to be reliable markers for the superposition of corresponding digital surface scans. Maxillary dentures processed with the injection molding technique have minimal deformation. Posterior denture teeth displace in 3 dimensions with the compression molding technique.

The Randomized Shortened Dental Arch Study: Tooth Loss Over 10 Years.

PURPOSE: This study aimed to compare the long-term outcomes of two different nonimplant treatments in the bilateral shortened dental arch (SDA). MATERIALS AND METHODS: In a multicenter randomized controlled clinical trial, patients with complete molar loss in one arch were assigned to one of two different nonimplant treatments. In the partial removable dental prosthesis (PRDP) group, patients were provided with a distal-extension prosthesis retained with precision attachments. In the SDA group, patients were treated according to the SDA concept by preserving or restoring a premolar occlusion. RESULTS: Of the 152 treated patients, 82 reached the 10-year examination independent of their dental or prosthetic status. In the intention-to-treat analysis, the survival rates for tooth loss at 10 years were 0.44 (95% confidence interval [CI]: 0.30 to 0.56) in the PRDP group and 0.52 (95% CI: 0.37 to 0.65) in the SDA group. For tooth loss in the study arch, the survival rates were 0.67 (95% CI: 0.52 to 0.78) in the PRDP group and 0.60 (95% CI: 0.45 to 0.73) in the SDA group. The number of teeth lost was higher than expected. In a multivariate analysis using a multiple Cox regression model, the covariates age (unit: 1 year, Hazard Ratio [HR]: 1.033, P = .03) and DMFT value (unit: 1 tooth, HR: 1.121, P = .03) were significant for time to first tooth loss in the study arch. CONCLUSION: The results suggest an overestimation of the influence of the prosthetic management of the bilateral SDA. In treatment decisions, patient preferences should be considered with appropriate weight.

Early implant placement for a patient with ectodermal dysplasia: Thirteen years of clinical care.

Patients with ectodermal dysplasia have abnormalities of 2 or more structures that originate from the ectoderm. The oral manifestations often include the congenital absence of teeth and malformed teeth. This clinical report describes the interdisciplinary care from childhood through the definitive dental rehabilitation completed at skeletal maturation to replace the missing teeth in a patient with ectodermal dysplasia. Treatment began at 9 years of age with an implant-assisted mandibular overdenture to improve function and replace the missing mandibular teeth. Orthodontic treatment for the consolidation of space, composite resin restorations, and interim removable dental prostheses were provided to improve esthetics and replace the missing maxillary teeth. Skeletal growth was monitored, and orthognathic surgery was performed at the cessation of growth. The definitive rehabilitation consisted of a mandibular fixed dental prosthesis supported by dental implants and a maxillary removable dental prosthesis to restore the patient to esthetics and function.

Effect of Cyclic Dislodging on the Retention of Two Attachment Systems for Implant-supported Overdentures: An In Vitro Study.

PURPOSE: The aim of this study was to compare and evaluate the retention of two new attachment systems used for implant-supported overdentures subjected to insertion-removal cycles. MATERIALS AND METHODS: Twenty custom-manufactured polyvinyl chloride models mimicking implant-retained over-dentureresin blocks were fabricated and divided into two groups (n = 10): group 1 ('Kerator' attachment) and group 2 ('EMI' attachment). Each model received two parallel implants (JD evolution®) 20 mm apart and was subjected to cyclic retention forces of 10, 100, 1000, 5000, 10000 and 14600 cycles using a universal testing machine in a 0.9% sodium chloride water solution at 22° C. Data were analyzed using one-way analysis of variance; the level of significance was set at a < 0.05. RESULTS: The 'Kerator' and 'EMI' attachment systems reported a significant decrease in retention (64 and 56.6% respectively) after 14600 insertion-removal cycles (p < 0.001). The 'EMI' attachment showed significant higher loss of retention than the 'Kerator' attachment all along the 14600 cycles (p < 0.05) except for cycles 100 and 5000 (p > 0.05). CONCLUSION: Within the limitations of this in vitro study, both attachments reported satisfactory retentive values during the 14600 cycles, the 'Kerator' attachment showed better retention than the new 'EMI' attachment. The initial retentive force of both attachments has gradually decreased. CLINICAL SIGNIFICANCE: Both attachment systems evaluated in this study can be used in clinical practice for implant-supported overdentures.

A Qualitative Study on Patients' Perceptions of Two Types of Attachments for Implant Overdentures.

The aim of this qualitative study was to gain a deeper understanding of patient perceptions of wearing implant-retained overdentures with ball-shaped or cylindrical attachment systems. Twenty-two wearers of implant-supported overdentures participated in this qualitative study based on a randomized crossover clinical trial that aimed to compare a cylindrical attachment and a ball attachment. In phase I of the study, group A experienced ball attachments (n = 11) and group B Locator attachments (n = 11) for 1 year. Afterward, in phase II, the attachments were changed; group A received Locator attachments and group B received ball attachments. One week after the attachment's replacement, semistructured individual interviews were conducted. All interviews were audiotaped and transcribed. The analysis was guided by thematic content analysis. Most of the patients from both groups preferred the attachment they received in phase II, regardless the type. A major theme raised by the participants to justify their preference between the attachment types was prosthesis retention/stability, sometimes considered as a positive and other times as a negative factor. Other themes were also explored: oral function, pain, hygiene, previous experiences, confidence on the dentist's work, and esthetic. Aspects related to the retention/stability of the overdentures are the main concerns associated with the perceptions of most patients treated with implant overdentures regardless of the type of attachment. Adequate retention level should be identified and adjusted on an individual basis and maintained overtime as possible. Therefore, follow-up appointments should be planned for readjustment of the attachment's retention. Overretention should be avoided.

Influence of Attachment Height and Shape on Lateral Force Transmission in Implant Overdenture Treatment.

PURPOSE: The purpose of this preliminary study was to examine the influence of overdenture attachment height and shape on lateral force on implants and denture displacement. MATERIALS AND METHODS: A straight model was fabricated to simulate the edentulous ridge. Two strain gauges were attached to the mesial and distal surfaces of the implant in the canine area. Five types of ball attachments and three types of Locator attachments with three types of replacement male attachments were used. A vertical load of 49 N was applied. The lateral force on the implant and the denture displacement were measured. Statistical comparisons were performed using one-way analysis of variance, Tukey post hoc comparison test, and multivariate analysis. P < .05 was considered significant. RESULTS: Ball attachments of 4-mm height exerted the highest lateral force on the implant, and the greatest displacement was also observed with attachments of 4-mm height. Different lateral forces were observed for different shapes of ball attachments, but there were no significant differences in denture displacement among the shapes. For Locator attachments, the highest lateral force was observed with the white male type, and the greatest denture displacement occurred with attachments of 4-mm height. There were no significant differences among male white, pink, and blue types. CONCLUSION: The height of the stud attachments in implant overdentures had a marked effect on the lateral force on implants and on denture displacement. To protect implants supporting an overdenture and to prevent bone resorption, the height of the attachment should be carefully considered.