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)

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)

Reabilitação oral utilizando prótese parcial removível associada a implantes osseointegrados: relato de caso / Oral rehabilitation using removable partial prosthesis associated with osseointegrated implants: case report

Introdução: As próteses parciais removíveis são alternativas amplamente utilizadas na reabilitação oral de pacientes parcialmente desdentados. Na atualidade os implantes dentais têm sido indicados para tratamento de pacientes edêntulos em associação com próteses parciais removíveis convencionais. Objetivo: Relatar um caso clínico utilizando uma prótese parcial removível convencional associada a implantes osseointegrados em paciente portador de Classe I de Kennedy. Relato de Caso: Paciente N.A.A.S., sexo feminino, 65 anos, procurou atendimento clínico no Instituto de Estudos da Saúde (IES) para reabilitação protética das arcadas dentais superior e inferior. A sua queixa principal era "dificuldade de mastigação". A paciente apresentava prótese total removível insatisfatória na maxila e não utilizava nenhum tipo de prótese dentária na mandíbula, que se apresentava parcialmente edêntula. O tratamento realizado foi a confecção de uma prótese total na arcada superior. Na arcada inferior foram inseridos dois implantes de hexágono externo nas regiões correspondentes às áreas dos dentes 34 e 44, após quatro meses a prótese parcial removível convencional foi confeccionada e incorporada aos implantes osseointegrados utilizando o sistema de retenção do tipo attachments Equator. Conclusão: Os resultados revelaram que a técnica de associação da prótese parcial removível convencional aos implantes osseointegrados demonstrou ser uma opção viável de tratamento com capacidade de devolver a função, a estética e manter a integridade dos dentes e tecidos periodontais(AU)

Introduction: Removable partial dentures are alternatives widely used in the oral rehabilitation of partially edentulous patients. Currently, dental implants have been indicated for the treatment of edentulous patients in association with conventional removable partial dentures. Objective: To report a clinical case using a conventional removable partial denture associated with osseointegrated implants in a patient with Kennedy Class I. Case Report: Patient N.A.A.S., female, 65 years old, sought clinical care at the Institute of Health Studies (HEI) for prosthetic rehabilitation of the upper and lower dental arches. His main complaint was "chewing difficulty". The patient had unsatisfactory removable total prosthesis in the maxilla and did not use any type of dental prosthesis in the mandible, which was partially edentulous. The treatment performed was the manufacture of a total prosthesis in the upper arch. In the lower arch, two external hexagon implants were inserted in the regions corresponding to the tooth areas 34 and 44, after four months the conventional removable partial denture was made and incorporated into the osseointegrated implants using the equator attachments retention system. Conclusion: The results revealed that the technique of associating conventional removable partial dentures with osseointegrated implants proved to be a viable treatment option with the ability to restore function, aesthetics and maintain the integrity of teeth and periodontal tissues(AU)

Three-dimensional finite element analysis of four-implants supported mandibular overdentures using two different attachments / 中华口腔医学杂志

Objective@#To compare the biomechanical characteristics of four-implants mandibular overdentures supported by Locator attachment or bar-clip attachment under different mechanical loads using three-dimensional finite element analysis method.@*Methods@#Two different models of four-implants supported mandibular overdentures using Locator attachment and bar-clip attachment (hereinafter called Locator model and bar-clip model) were established. Each model was subjected to five different mechanical loading conditions: 100 N vertical loading in central incisor (vertical load of incisor), 100 N vertical loading or oblique loading in canine (vertical or oblique loads of canines), 100 N vertical or oblique loading in mandibular first molar (vertical or oblique loads of mandibular first molar). The stress distributions in implants, peri-implant bone and mucosa were recorded under the above five conditions to evaluate the effects of different attachments on the biomechanical properties of implant-supported mandibular overdentures.@*Results@#Regardless of loading conditions and types of attachments, the stress concentration in implants were located at the neck of implants, and the stress concentration in peri-implant bone was located in the cortical bone. The stress values in mucosa were always much smaller than those in implants and cortical bone. Regardless of loading positions (on canine or on mandibular first molar), the maximum stress at the bone interface around the implant under lateral loading was much higher than that under vertical loading. Under various loading conditions, the stress in implants and cortical bone of the Locator model (the highest von Mise stress value was respectively 79.5 and 22.3 MPa) were lower than that of bar-clip model (the highest von Mise stress value was 110.3 and 28.7 MPa respectively) while the maximum compressive stress in mucosa (0.198 MPa) in Locator model was slightly higher than that in the bar-clip model (0.137 MPa).@*Conclusions@#In clinical practice, the lateral force applied to the implant-retained overdenture should be minimized to avoid complications caused by pathological loads. Under the same loading condition, the stress distributions in overdenture using Locator attachment are more dispersed, which is more conducive to long-term stability of implants.

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.

Comparação dos sistemas de retenção para overdenture / Comparison of different attachment systems for overdenture

As próteses totais convencionais inferiores são as mais difíceis de adaptar, devido à perda óssea ser maior e consequentemente à baixa estabilidade e pouca retenção. Entretanto, com o aparecimento dos implantes osse-ointegráveis surgiram os tratamentos com próteses do tipo overdenture, as quais oferecem melhor estabilidade e retenção. O objetivo deste trabalho foi comparar os três principais tipos de sistemas de retenção para a pró¬tese overdenture encontrada na literatura. Para isso, foram realizadas pesquisas com os termos "overdenture"; "attachment", "implant-supported", "dental prosthesis", "denture" e "oral rehabilitation" nas bases de dados PubMed, Science Direct e Scielo. Os sistemas barra-clipe e esférico apresentaram semelhanças estatísticas quanto à retenção e estabilidade. Já o sistema magnético apresentou pouca retenção e baixa estabilidade

The conventional lower total prosthesis is the most difficult dental prosthesis to adapt in the patients mouth, due to bone loss be greater in this region, which consequently decreases stability and retention of the prosthe¬sis. However, the appearance of osseointegrated implants gave rise to treatments with overdenture prostheses, which offer better stability and retention to the prostheses. The aim of this study was to compare the three main types of overdenture prosthesis restraint systems found in the literature. For this research, we used the terms: "overdenture"; "attachment", "implant-supported", "dental prosthesis", "denture" and "oral rehabilitation" in the databases of PubMed, Science Direct and Scielo. The clip bar and spherical systems presented statistical similarities regarding retention and stability. Already, the magnetic system presented little retention and low stability

Reabilitação oral com uso de prótese parcial removível com encaixe de precisão em paciente que fez uso de bisfosfonatos ­ relato de caso / Oral rehabilitation with removable partial prosthesis with attachments in bisphosphonates user ­ case report

Os medicamentos antirreabsortivos, como os bisfosfonatos, são usados para tratamento de diversas patologias ósseas. Uma de suas complicações relacionadas à Odontologia é a osteonecrose dos maxilares e o tratamento conservador deve ser a primeira opção. Em casos de pacientes total ou parcialmente edêntulos que fazem uso de medicamentos desta classe, as próteses são mais convenientes para reabilitação. Sabemos que estética é um dos fatores de maior relevância para o paciente, o que torna cada vez mais difícil a aceitação de próteses que contenham grampos, como as próteses parciais removíveis e que, por mais criterioso que seja o planejamento, a associação de suporte, retenção, estabilidade e estética sempre deixa a desejar. O objetivo deste relato de caso foi mostrar uma reabilitação sem a instalação de implantes, a prótese parcial removível, com encaixe de precisão em paciente que faz uso do medicamento e que prezava por uma estética satisfatória.

Antiresorptive drugs such as bisphosphonates are used to treat several bone diseases. Their complication related to Dentistry is osteonecrosis of the jaw and a conservative treatment should be the first option. In cases of total or partially edentulous patients that make use of this class of medication prostheses are more convenient for rehabilitation. It is known that aesthetics is one of the most important factors for the patient and this hampers the acceptance of prostheses with staples such as removable partial dentures. And it doesn't matter how judicious the planning the association of retention, support, stability and aesthetics always falls short. The objective of this report was to present rehabilitation without implant installation using removable partial denture with precision fit in a bisphosphonates who wished a satisfactory aesthetic outcome.

Prosthetic reconstruction with an obturator using swing-lock attachment for a patient underwent maxillectomy: A clinical report

Patients who underwent resection of maxilla due to benign or malignant tumor, or accident will have defect in palatal area. They get retention, support and stability from remaining tissues which are hardly optimal. The advantage of swing-lock attachment design is having multiple contacts on labial and lingual side of the abutment teeth by retentive strut and palatal bracing component. Because the force is distributed equally to abutment teeth, abutment teeth of poor prognosis can be benefited from it. It is also more advantageous to cover soft tissue defects which are hard to reach with conventional prosthesis. A 56-year-old female patient who had undergone a maxillectomy due to malignant melanoma complaining of loose and unstable surgical obturator. Surveyed crowns were placed on #12, 26, and 27. Teeth #11, 21, 22, and 23 had lingual rest seat and #24 had mesial rest seat to improve stability and support of the obturator. This clinical report presents the prosthetic management of a patient treated with obturator on the maxilla using swing-lock attachment to the remaining teeth.

Influence of attachment type on stress distribution of implant-supported removable partial dentures / 北京大学学报(医学版)

Objective: To compare influences of different retention attachments on stress among supporting structures .Methods: By 3-dimensional laser scanner and reverse engineering computer aided design ( CAD) software , a basic partially edentulous digital model with mandibular premolar and molar missing was established .Implant attachment and removable partial dentures ( RPD) were added into the basic model to build three kinds of models: RPD only, RPD +implant +Locator attachment , and RPD +implant +Magfit attachment .Vertical and inclined loads were put on artificial teeth unilaterally . By means of 3-dimensional finite element analysis , the stress distribution and displacement of the main supportive structures were compared . Results: A complete 3-dimensional finite element model was established , which contained tooth structure , and periodontal structures .The displacement of the denture was smaller in Locator (9.38μm vertically, 45.48μm obliquely) and Magfit models (9.54μm vertically, 39.45 μm obliquely) compared with non-implant RPD model (95.27 μm vertically, 155.70 μm oblique-ly) .Compared with the two different attachments , cortical bone stress value was higher in Locator model ( Locator model 10.850 MPa vertically , 43.760 MPa obliquely;Magfit model 7.100 MPa vertically , 19.260 MPa obliquely).The stress value of abutment periodontal ligamentin Magfit model (0.420 MPa vertically) was lower than that in Locator model (0.520 MPa vertically).Conclusion:The existence of implant could reduce maximum von Mises value of each supportive structure when Kennedy Ⅰpartially edentulous mandible was restored .Comparing the structure of Magfit and Locator attachment , the contact of Magfit attachment was rigid , while Locator was resilient .Locator attachment could improve stability of the denture dramatical -ly.Locator had stronger effect on defending horizontal movement of the denture .

A meta-analysis of effectiveness of an implant-supported mandibular overdenture retained with a ball attachment / 中国组织工程研究

BACKGROUND:There is no design that can completely rule out the intermittent impact damage to implants, therefore, a new bal attachment-retained implant system is constantly updated and developed. OBJECTIVE:To evaluate the clinical effectiveness of an implant-supported mandibular overdenture retained with a bal attachment. METHODS: We searched the Cochrane Library, PubMed, Medline, EM-base, WanFang Data, CNKI, VIP and other databases by computer to colect randomized controled trials addressing the implant-supported mandibular overdenture retained with a bal attachment and other control methods for dentures. The time limit was from database creation to February 2014. Two researchers independently completed literature screening according to inclusion and exclusion criteria, data extraction and quality assessment. RevMan 5.1 software was used for meta-analysis. RESULTS AND CONCLUSION: There were 10 studies included in result analysis, including 7 from China and 3 from other countries. Analysis results showed that statistical heterogeneity was remarkable in included studies, and there was no significant difference in patient’s satisfaction, clinical and objective indicators, and complications, suggesting that this approach continues to be explored in clinic. The implant-supported bal attachment-retained mandibular overdenture is relatively expensive, which is identical with the current research progress that is in the exploration stage worldwide. Due to the limited quantity and quality of included studies, the conclusions of this systematic review only provide references for clinical practice and research. The implant-supported bal attachment-retained mandibular overdenture stil needs further exploration and improvement.

Uso do sistema MK1 em overdenture implantossuportada para reabilitação do suporte labial deficiente / Restoring deficient upper lip support with implant-supported overdentures associated with the MK1 attachment system

A reabilitação com implantes da maxila desdentada é muitas vezes dificultada pela reabsorção óssea excessiva em sua região anterior, após a perda dos dentes, levando a um suporte labial deficiente. As overdentures são recomendadas para estes casos pela presença da flange vestibular, que se estende até o fundo de vestíbulo labial e proporciona maior suporte ao lábio do paciente. O objetivo deste estudo foi apresentar o caso clínico de um paciente reabilitado com overdenture suportada por implantes e fixada pelo sistema de encaixes MK1. Durante exame clínico inicial, foi identificada a ausência de suporte labial para proporcionar a estética labial necessária para a resolução do caso com próteses fixas totais convencionais suportadas por implantes (prótese/protocolo). A overdenture suportada por implantes dentários permitiu o restabelecimento do suporte labial perdido pelo paciente, contribuindo para a boa estética facial final do caso e o restabelecimento da função mastigatória. O sistema de encaixes MK1 também proporcionou o conforto de uma prótese fixa, sem cobertura palatina, mas com fácil dispositivo para sua remoção, facilitando a higienização adequada.

Severe bone resorption of the edentulous anterior maxilla leads to deficient upper lip support and difficult implant rehabilitation. Overdentures are recommended because of the presence of the anterior flange extension that provides adequate lip support. This study present a clinical case of an edentulous patient rehabilitated with an overdenture supported by dental implants and associated with the MK1 precision attachment system. Deficient upper lip support was diagnosed during clinical exam preventing treatment with an implant-fixed dental prosthesis. The use of the MK1 attachment system on the implant-supported overdentures allowed the adequate upper lip support that the patient needed, contributing to the final facial esthetics and the reestablishment of masticatory function. The attachment system also provided characteristics of an implant-fixed restoration, without palatal covering and also provided easy access for adequate oral hygiene procedures.

Prótese parcial removível com attachment para reabilitação oral: relato de caso / Removable dental prosthesis with attachment for oral rehabilitation: a clinical report

Abordar os principais aspectos relacionados à reabilitação oral ao relatar um caso clínico utilizando prótese parcial removível (PPR) com attachment ball. Discussão: As próteses implanto-suportadas são consideradas um tratamento efetivo para a reabilitação de muitos pacientes desdentados parciais. No en¬tanto, limitações ósseas e/ou sistêmicas e o custo elevado dos implantes podem contraindicar essa modalidade terapêutica. Assim, a reabilitação oral com PPR torna-se uma ótima opção de tratamento. É conhecido que as PPRs a grampo não apresentam boa estética em muitas situações clínicas; porém, PPRs associadas a attachments permitem diversas possibilidades de soluções clínicas quando um diagnóstico e plano de tratamento mais elaborado podem ser executados. Conclusão: A PPR retida por attachment propicia resultado estético superior, transmissão adequada da carga mastigatória aos dentes suportes e excelente retenção...

To discuss the main aspects related to oral rehabilitation through the report of a clinical case using removable dental prosthesis (RDP) with ball attachment. Discussion: The implant-supported fixed restorations are considered an effective treatment for the rehabilitation of many partially edentulous patients. However, bone and/or systemic limitations and the high cost of implants may contraindicate this therapeutic modality. Thus, the oral rehabilitation using RDP becomes a great treatment option. It is known that RDP retained to a clip do not present a good esthetic in several clinical conditions; however, the RDP with attachments allows several possibilities for clinical solutions when a diagnosis and a more elaborated treatment plan can be performed. Conclusion: The RDP with attachment provides better aesthetical result, adequate transmission of masticatory load to support teeth and an excellent retention...

Performance of attachments used in implant-supported overdentures: review of trends in the literature

The purpose of this review is to examine the performance of attachments used in implant-supported overdenture (IOD) in both clinical and in vitro settings and report the compiled findings, comparisons, and trends in the research literature. Articles published in PubMed on IOD attachment systems and performance were reviewed. Non-original articles were excluded. For each article included, the type of study, number of implants, number of attachment systems, and study outcome were recorded. Of the 283 articles found, 158 met the inclusion criteria. Ninety-four articles were clinical studies and 64 articles were in vitro studies. Studies on retention were the most common for in vitro studies, and four or more attachment systems were compared in most articles with significant differences in outcome. A clinical outcome of one attachment system was most common for clinical studies, while most studies had neutral outcomes overall. Ball attachment was the most commonly tested IOD attachment system. The trend in the literature showed that there is a large discrepancy between the study designs and outcomes between the clinical and the in vitro studies for IOD. Further clinical studies that can validate in vitro research should be encouraged to address this discrepancy between the two areas.

Wear of double crown systems: electroplated vs. casted female part

OBJECTIVES: The wear of telescopic crowns is a common problem often reducing the patient's satisfaction with the denture and resulting in a renewal of the denture. The study aims to compare the wear behavior of conical crowns using electroplated copings (group E ) with standard telescopic crowns with cast female parts (group C). MATERIAL AND METHODS: 10 conical crowns were milled for each group of a cast gold alloy. The specimen of group E had a conicity of 2º. The cast secondary crowns of group C had a 0º design. The electroplated coping was established by direct electroforming. An apparatus accomplishing 10,000 wear cycles performed the wear test. The retentive forces and the correlating distance during insertion and separation were measured. The wear test was separated in a start phase, an initial wear phase and the long term wear period. The retention force value and the force-distance integral of the first 0.33 mm of each cycle were calculated. RESULTS: The retentive forces were significantly higher for group E and the integrals were significantly lower for this group except the integral at cycle 10,000. The changes of retention force and integral did not differ significantly between both groups in all phases. The change of the integrals as well as the integral at the particular cycles showed higher interquartile distances for group C. CONCLUSIONS: Within the limitations of this study the tested conical crowns showed clinically acceptable retentive properties. The values reached a range comparable to retentive elements tested in recent literature. The values of group C showed higher ranges. The force measured for group E was significantly higher than for group C but the integrals showed an opposite tendency. The results indicate that an exclusive analysis of the force is not sufficient as the integral is not equivalent to the force although it describes the retentive property of the system in a better way than the force over a distance is described. Both systems seem to be suitable for clinical practice.

Comportamento de desgaste “in vitro” de encaixes de precisão extracoronários / “In vitro” wear behavior of extracoronal precision attachments

The objective of this study was to evaluate the retentive ability and weight change of two extracoronal attachments after repeated insertion/removal cycles. Material and methods: Two extracoronal attachments were used, one with plastic inserts and the other one with conventional metal-alloy. Initial retentive ability was checked under a 20kgf load cell at 5mm/min. The weight of the fixed/removable pairs was verified with an electronic mass comparator. Fixed/removable pairs were tested with an insertion/removal cycling machine, for 5800 cycles (corresponding to 5 years) at a speed of 32 rpm speed. Insertion/ removal cycles were performed under artificial saliva. Weight change and retentive ability of attachments were verified at baseline, six-month, one-year, two-year, three-year, four-year and five-year time intervals. The two-way ANOVA for repeated measurements test was used to verify possible interactions between precision attachment type and retentive ability/weight change over time. Statistically significant associations were found between attachment type and retentive ability over time (P=0.006). Metal-alloy group showed signifi cant differences between baseline and first year (P=0.005), baseline and second year (P=0.001), and between baseline and five years (P=0.035) of insertion/removal cycles. In the plastic insert group, no significant differences were found over time. No statistically significant associations were found between precision attachment types and weight change over time (P=0.643). Initial retentive ability can not be standardized for both attachments; the metal-alloy showed better performance than the plastic insert after five years. Both attachments did not show weight change after five years of simulated use.

O objetivo deste estudo foi avaliar a capacidade retentiva e a alteração do peso de dois encaixes extracoronários após repetidos ciclos de inserção e remoção. Materiais e métodos: Dois encaixes extracoronários foram usados, um com fêmea em plástico e o outro em metal. A capacidade retentiva inicial foi verificada em uma máquina de ensaio universal com célula de carga de 20kgf a velocidade de 5mm/min. O peso do conjunto macho/fêmea foi verificado com uma balança eletrônica. Os conjuntos macho/fêmeas foram testados em um simulador de ciclos por 5800 vezes (correspondendo a 5 anos) a uma velocidade de 32 rpm. Os ciclos de remoção e inserção foram realizados com saliva artificial. A alteração de peso e a capacidade retentiva dos encaixes foi verificada inicialmente e nos intervalos de tempo de 6 meses, um, dois, três, quarto e cinco anos. O teste ANOVA foi usado para verificar possíveis interações entre o tipo de encaixe e a capacidade retentiva/alteração de peso com o tempo de uso. Associação estatisticamente significativa foi encontrada entre o tipo de encaixe e a capacidade retentiva com o tempo de uso (P=0.006). O grupo metálico mostrou diferença significante entre o tempo inicial e o primeiro ano (P=0.005), tempo inicial e o segundo ano (P=0.001), e entre o tempo inicial e cinco anos (P=0.035) de inserção e remoção. No grupo com fêmea de plástico, não foram encontradas diferenças significativas. Associações estatisticamente significativas não foram encontradas entre os tipos de encaixes e a alteração de peso em tempo algum. (P=0.643). A capacidade retentiva inicial não pode ser padronizada nos dois encaixes; o grupo com fêmea em metal mostrou melhor performance retentiva que o grupo com fêmea em plástico após cinco anos. Ambos encaixes não mostraram alteração no peso após uso simulado de cinco anos.

Prótese parcial removível destacável com sistemas MK1: descrição de técnica laboratorial / Dettachable removable partial denture with MK1 system: description of laboratory technique

A reabilitação oral através de próteses parciais removíveis ainda é uma constante na clínica odontológica apesar do grande avanço técnico-científico da Odontologia Restauradora. Dentro da reabilitação com próteses parciais removíveis, os attachments merecem especial destaque, e o sistema MK1 representa um tipo de attachment de precisão do tipo trava e com funcionamento rígido, que pode ser utilizado sobre dentes, raízes e implantes. Na reabilitação de desdentados parciais, esse sistema pode ser empregado conjugado a próteses fixas convencionais, servindo-se de retenção para próteses parciais removíveis. Em virtude da pouca visibilidade do sistema MK1 perante os protesistas e os técnicos em prótese dental e das dificuldades de execução da técnica laboratorial, esse trabalho tem o objetivo de retratar os mais relevantes aspectos relacionados à execução laboratorial desse sistema. Os autores concluem que a utilização do sistema MK1 constitui-se uma alternativa protética satisfatória, apesar de exigir experiência e uma rigorosa execução dos procedimentos laboratoriais.

Oral rehabilitation removable partial denture has been a very common clinical treatment although it may be seen a great technical and scientific increasing of restorative dentistry. Considering the use of removable partialenture, attachments are in ividence, and MK1 system reoresents a precision locked attachment with rigid working, and it may be used over teeth, roots and implants. That system can be used together fixed partial dentures, offering retention for removable partial dentures in the partially edentulous patients. Because of the little use of MK1 system by prosthodontists and dental technicians, and the difficulties that characterizes its laboratory technique, this work has an aim to present the more important aspects about the MK1 technique. Authors conclude the use of MK1 attachment together removable partial denture represents a satisfactory prosthetic options, although that technique requires experience and a meticulous execution of the laboratory procedures.

Comparison of stress distribution in abutment and alveolar ridge between two kinds of distal-extention absence dentures / 吉林大学学报(医学版)

Objective To analyze the stress distribution of abutment and alveolar ridge between two kinds of distal-extention absence dentures,and provide evidence for the application of different dentures in clinic.Methods Attachment denture and cantilever fixed bridge were used to restore the distal-extention absence respectively,the stress distribution of abutment and alveolar ridge was compared by three-dimensioal finit element method.Results The stress peak values of abutmen root,periodontal membrance,alveolar ridge were(1.42E+5)MPa,(1.33E+4)MPa and(3.49E+5)MPa,respectively,in attachment denture;while in cantilever fixed bridge,the stress peak values of them were(1.45E+7)MPa and(2.25E+6) MPa,(1.45E+3)MPa,respectively.And the stress peak values of these two kinds of dentures were all located in the mid-upper 1/3 and the cervical of abutment.Conclusion Compared with cantilever fixed bridge,the attachment denture could decrease the stress of abutment and be helpful to its protection,the hight of residual alveolar ridge should be taken into account when the two kinds of dentures are used for distal-extention absence.

A pilot study on the effects of Mini-SG~ F attachments on periodontal health of the abutment teeth used in free-end partial removable dentures / 北京大学学报(医学版)

Objective : To investigate the effects of Mini-SG~ F attachment on periodontal health of the abutment teeth in restoring free-end removable partial dentures (RPDs). Methods : The periodontal status of the abutments in restoring free-end RPDs was longitudinally observed with periodontal indices commonly used in clinics, and a group comparison was made using a one-way analysis of variance (ANOVA). Results: The stability and retention of free-end RPDs retained by Mini-SG~ F attachments were excellent during the whole observation course. Compared with the periodontal status of the first and the second abutments before restoration respectively, no significant differences in gingival indices, plaque indices, periodontal probing depth, alveolar bone resorption levels of those were shown 6 months after restoration. The mobility of the abutments was significantly reduced when they were splinted together. Conclusion: Mini-SG~ F attachments used in free-end RPDs have no evident adverse effect on periodontal health of the abutment teeth, and the way of splinting the abutments is advantageous to their long-term health and stability.