Marginal and internal fit of zirconia copings obtained using different digital scanning methods

Abstract The objective of this study was to evaluate the marginal and internal fit of zirconia copings obtained with different digital scanning methods. A human mandibular first molar was set in a typodont with its adjacent and antagonist teeth and prepared for an all-ceramic crown. Digital impressions were made using an intraoral scanner (3Shape). Polyvinyl siloxane impressions and Type IV gypsum models were also obtained and scanned with a benchtop laboratory scanner (3Shape D700). Ten zirconia copings were fabricated for each group using CAD-CAM technology. The marginal and internal fit of the zirconia copings was assessed by the silicone replica technique. Four sections of each replica were obtained, and each section was evaluated at four points: marginal gap (MG), axial wall (AW), axio-occlusal edge (AO) and centro-occlusal wall (CO), using an image analyzing software. The data were submitted to one-way ANOVA and Tukey's test (α = 0.05). They showed statistically significant differences for MG, AO and CO. Regarding MG, intraoral scanning showed lower gap values, whereas gypsum model scanning showed higher gap values. Regarding AO and CO, intraoral digital scanning showed lower gap values. Polyvinyl siloxane impression scanning and gypsum model scanning showed higher gap values and were statistically similar. It can be concluded that intraoral digital scanning provided a lower mean gap value, in comparison with conventional impressions and gypsum casts scanned with a standard benchtop laboratory scanner.

Dimensional stability of a novel polyvinyl siloxane impression technique

AIM: To introduce a modification of the reline impression technique (MRIT), and compare the dimensional changes of impressions obtained by MRIT and by conventional reline impression technique (CRIT). METHODS: An acrylic resin tablet was milled by a CAD-CAM system to simulate three abutments (A, B and C) with different distances among them. The abutments were molded using both impression techniques. For MRIT, before completing the putty silicone polymerization, the relieve procedure was made by compression and it was immediately repositioned to complete the polymerization. Impressions were stored dry at room temperature for different periods (immediately, 1 h, 2 days and 7 days). The distances were obtained by scanning. The differences between the impressions and their respective matrix reference measurements were calculated to determine the dimensional changes. Data were subjected to ANOVA and Tukey's test (p<0.05). RESULTS: For AB and BC distances, there was no statistically significant difference between CRIT and MRIT (p=0.0597 and p=0.2167, respectively). For AC, there was statistically significant difference between the techniques for the immediate storage time (p=0.006). In general, for CRIT the material showed expansion, while for MRIT it showed contraction. CONCLUSIONS: It was verified that the addition silicon impressions obtained by both impression techniques showed dimensional stability, except for the immediate time-point...

Analysis of tensile strength of poly(lactic-coglycolic acid) (PLGA) membranes used for guided tissue regeneration

Introduction: The challenge of restoring patient's function that presented some loss of an organ or tissue encourages the Tissue Engineering and Biotechnology to develop materials that promote bone regeneration. Poly(lactic-co-glycolic acid) (PLGA) copolymer is among of the most biomaterials used. Objective: To evaluate the tensile strength of PLGA membranes at different conditions of humidity and temperature. Material and methods: PLGA membranes were hourglass-shape cut and prepared at three different conditions of temperature and humidity (n = 10): (I) dry membrane at environment temperature of about 20ºC (control group), (II) moist membrane plasticized at 55ºC, (III) moist membrane plasticized at 55ºC, which subsequently underwent cooling. Subsequently, the membranes were subjected to tensile tests in a universal testing machine (DL-2000, EMIC) at 1.0 mm/min. Data was submitted to ANOVA and Tukey's test (p < 0.05). Results: Group I showed the highest tensile strength mean (16.7 ± 1.9a MPa, p = 0.0022). There was no statistically significant difference between the means of groups II (14.6 ± 1.4 MPab) and III (13.9 ± 1.7 MPab). Conclusion: The dried PLGA membranes showed higher tensile strength than the membranes that were only either plasticized or cooled.

Estética periimplantar em cirurgias de segundo estágio: relato de caso / Peri-implant esthetics in second-stage surgeries: a case report

Artigo de apresentação de caso clínico em que se utilizam técnicas de manejo tecidual associadas a procedimentos protéticos preestabelecidos na região do dente 11, os quais proporcionam completa reabilitação da estética e função. Por meio da discussão e descrição detalhada dos procedimentos cirúrgico-protéticos envolvidos, concluímos que os cuidados ao se manipular os tecidos moles na cirurgia de segundo estágio de implantes, assim como a utilização conjunta dos recursos advindos das técnicas protéticas, são fundamentais quando se quer aperfeiçoar a estética e aumentar a proteção natural dos implantes

The aim of this article is to report a clinical case in which an alternative procedure was used at the second-stage implant surgery of a right central maxillary incisor (tooth #8). A detailed description of surgical and prosthetic procedures in provided and discussed. It was concluded that the second-stage implant surgery should be performed in association with prosthetic procedures in order to optimize the esthetics and to achieve natural life-like implants rehabilitations

Adaptação marginal em prótese livre de metal, observada por meio de microscopia eletrônica de varredura, após três anos em função / Marginal fit of metal-free crown, observed in scanning electron microscope after three years in function

Introdução: As cerâmicas são consideradas uma excelente alternativa como material estético restaurador, entretanto questões relevantes, como adaptação marginal, exigem um maior critério na confecção quando comparadas aos sistemas convencionais. Objetivo: Este trabalho avaliou a adaptação marginal de uma coroa In-Ceram confeccionada sobre um dente que, após 3 anos, teve sua extração indicada pela ortodontia. Material e métodos: A avaliação deu-se por meio de microscópio eletrônico de varredura. Resultados e conclusão: Foram encontrados valores de falta de adaptação entre 157 e 390 um, obtendo uma média estatística acima do considerado aceitável clinicamente pela literatura.

Introduction: Ceramics are considered an excellent choice as esthetic restorative material, but relevant questions like marginal fit require more attention in manufacturing than conventional systems. Objective: This work evaluated the marginal adaptation of an In-Ceram crown over a tooth that, after three years, had been indicated to extraction by orthodontics. Material and methods: The evaluation was by mean scanning electron microscope. Results and conclusion: It was found values of gaps between 157 and 390 um, getting a statistic average considered greater than the accepted by literature.

Avaliação da satisfação de pacientes reabilitados por implantes osseointegráveis / Evaluation of patients satisfaction treated by osseointegrated implants

O objetivo deste estudo é avaliar a satisfação com o tratamento restaurador de um grupo de pacientes que receberam implantes osseointegráveis. Assim como correlacionar tais escores com as etapas cirúrgicas e/ou protéticas e com os resultados funcionais deste tratamento. Por meio de uma análise retrospectiva foram selecionados 122 pacientes tratados com implantes dentários utilizando-se protocolo de dois estágios, sendo que 43 são homens e 79 mulheres, na faixa etária entre os 22 e 74 anos. Os implantes foram instalados e restaurados com próteses fixas metalocerâmicas, metaloplásticas e coroas puras de acrílico. Num período de 12 a 72 meses após a instalação da prótese fixa, estes pacientes responderam a um questionário de 22 perguntas relativas à etapa de instalação dos implantes, segunda etapa cirúrgica, confecção e adaptação com a nova prótese, custo, qualidade mastigatória e dificuldade de mastigação, utilizando a Escala de Análise Visual (VAS). Os valores atribuídos foram transformados em escores e divididos em quatro grupos de acordo com o grau de satisfação do paciente. Os valores atribuídos às respostas foram mensurados e agrupados em escores assim divididos: (1) Totalmente insatisfeitos (de zero a 25 mm); (2) Parcialmente insatisfeitos (de 26 mm a 50 mm); (3) Parcialmente satisfeitos (de 51 mm a 75 mm); e (4) Totalmente satisfeitos (de 76 mm a 100 mm). Dos 122 pacientes analisados, 48 demonstraram não estar totalmente satisfeitos. Os motivos manifestados de algum descontentamento estavam na etapa de instalação do implantes (15); segunda etapa cirúrgica (9), dificuldades no momento de confecção ou adaptação com a nova prótese (6). Os outros motivos também manifestados de insatisfação parcial foram o custo do tratamento, a qualidade mastigatória e a dificuldade de higienização. Com relação aos pacientes avaliados neste estudo, o tratamento com implantes osseointegráveis e próteses fixas sobreimplantes apresentaram um grau elevado de satisfação...

The purpose of the present study was to evaluate the degree of satisfaction of a group of patients treated by osseointegrated implants. So that, correlate the scores with the surgical and/or prosthetic procedures, and with the functional results. One hundred twenty two patients treated by dental implants in a two stage protocol were selected for the study. All the implants were placed and restored by fixed prostheses and investigated during a period of 12 to 72 months. The patients answered to 22 questions regarding to the treatment by mean of a visual analog scale(VAS), 12 to 72 months after the prostheses confection. The values were transformed in scores and divided into 4 groups in accordance with the patient satisfaction degree. Among the 122 analyzed patients, 48 seem to be not completely satisfaction. From this 48 patients group, 15 expressed discomfort during placing the implants, 9 during the reopening and 6 during the new prostheses confection period. Another points cited as partial satisfaction results were the treatment coast, masticator quality and hygiene difficult. Among the patients evaluated in the present study, dental implants and fixed prostheses presented high degree of general satisfaction with the treatment.

Evaluation of the marginal adaptation of a fibre glass reinforced resin crown using a scanning electronic microscope / Avaliação da adaptação marginal de coroa deresina reforçada com fibra de vidro emmicroscópio eletrônico de varredura

Introduction and objective: Dental prostheses manufactured using reinforced resins are an alternative to the rehabilitative treatment of one or more dental elements. With the aim of forecasting the longevity of these prosthetic pieces, this study evaluated the marginal adaptation of a complete crown made from fibreglass reinforced resin. Material and methods: A tooth having orthodontic indication for extraction was prepared and a prosthetic piece was cemented over it so that, 48 hours later, the extraction could take place. The ensemble was taken in a laboratory and was examined using a scanning electron microscope (SEM). There were made 30 readings in a 8mm toothcement-restoration interface and revealed various gaps throughout the sample. Results: The lowest value found was 15,82 µm and the highest was 72,81 µm showing an average value of 40,82 µm. Conclusion: The gaps were within the limits of clinical tolerance and considering the clinical difficulty in making the prosthetic piece, the treatment was shown to be satisfactory with regard to marginal adaptation.

Introdução e objetivo: As próteses fabricadas com resinas reforçadas são alternativas para o tratamento reabilitador de um ou mais elementos dentários. Objetivando prever a longevidade dessas peças, este trabalho avaliou a adaptação marginal de uma coroa total confeccionada com resina reforçada com fibra de vidro. Material e métodos: Um dente com indicação ortodôntica de exodontia foi preparado e sobre ele uma peça protética foi cimentada para que, 48 horas depois, a extração fosse executada. O conjunto foi levado ao laboratório para leitura em microscópio eletrônico de varredura (MEV). Foram feitas 30 leituras em uma interface de dente-cimento-restauração de 8 mm e reveladas diferentes gaps em toda a amostra. Resultados: O menor valor achado foi de 15,82 µm, e o maior de 72,81 µm, resultando em uma média de 40,82 µm. Conclusão: As gaps estavam dentro dos limites de tolerância clínica e, considerando a dificuldade clínica de produção da peça protética, o tratamento mostrou-se satisfatório no que concerne à adaptação marginal.