Removal torque of zirconia abutment screws under dry and wet conditions

The aim of this study was to verify whether screw abutment lubrication can generate higher preload values compared to non-lubricated screws, a titanium abutment was screwed onto an implant analog and scanned with the Procera System to generate 20 zirconia abutments. MKIII Brånemark implants were clamped to a precision torque device, and the abutments were distributed in dry and wet groups with 10 specimens each. In the wet groups, the inner threads of the implants were filled with artificial saliva. All abutments were fastened with a Torqtite screw under 32 Ncm. Ten detorque measurements were performed per group pushing the reverse button of the Torque controller soon after screw tightening with values registered. The mean detorque values were calculated and compared by a Student's t test (?=0.05). The wet condition presented significantly higher mean detorque than the dry condition (31.5 ± 1.2 versus 27.5 ± 1.5 Ncm, respectively; p=0.0000024). In conclusion, there was always a loss in the initial torque values when the removal torque was measured under both conditions. The wet condition presented higher mean torque than the dry condition. Better preload values were established in the wet group, suggesting that the abutment screw must be lubricated in saliva to avoid further loosening.A fim de verificar se a lubrificação do parafuso do pilar pode gerar valores maiores de pré-carga do que nos parafusos não lubrificados, um pilar de titânio foi parafusado no análogo do implante e escaneado pelo Sistema Procera para gerar 20 pilares de zircônia. Depois, os implantes MKIII Brånemark foram presos num dispositivo de torque. Os pilares foram distribuídos em grupos seco e úmido com 10 amostras cada. No grupo úmido, as roscas internas dos implantes foram preenchidas com saliva artificial. Então, todos os pilares foram apertados com parafuso Torqtite a 32 Ncm. Dez medidas de destorque foram realizadas por grupo apertando-se o botão reverso do Torque Controller logo depois do parafusamento, e os valores foram registrados. As medias de destorque foram calculadas e comparadas pelo teste t de Student (?=0,05). Os valores médios obtidos nas condições seca e úmida foram 27,5 ± 1,5 Ncm e 31,7 ± 1,2 Ncm, respectivamente. Diferenças estatisticamente significantes foram observadas (p=0,0000024). Observou-se sempre existir uma perda do torque inicial quando o torque de remoção é mensurado em ambas as condições. A condição úmida demonstrou um valor médio maior de torque do que a condição seca. Valores melhores de pré-carga podem ser estabelecidos no grupo úmido, sugerindo que o parafuso do pilar deve ser lubrificado em saliva para evitar seu afrouxamento

Avaliação in vitro da resistência de união de diferentes combinações entre adesivos e resinas compostas

The aim of this work was to evaluate the in vitro compatibility between some composite resins (Herculite XR, Z100 and AP.H) and different adhesives (XR-Bond, Scotchbond MP and PUB3), since for various reasons, the utilization of composite resins and adhesives from different commercial brands is very frequent in the dental practice. We used a device constituted of a base and a matrix which, when juxtaposed, showed a cavity in dumbbell shape which received the composite resin. Firstly, 45 half-specimens of each composite resin were made and stored in distilled water at 37ºC for one week. Then, they were replaced in the matrix for the building of the second half and divided into groups to combine each composite resin with each one of the three adhesives. The specimens were stored in distilled water at 37ºC and after the period of 7 days they were submitted to the tensile strength test in a Kratos machine. It was concluded that: generally, the composite resins and the adhesives showed to be compatible; the combination AP.H/XR-Bond showed the highest discrepancy, since the tensile strength was statistically smaller than that of the combination proposed by the manufacturer; the other combinations of the adhesives and the composite resins showed tensile strengths statistically similar to or greater than that of the combination recommended by the manufacturer.O objetivo desta pesquisa foi avaliar in vitro a compatibilidade entre as resinas compostas Herculite XR, Z100, AP.H e os diferentes adesivos XR-Bond, Scotchbond MP e PUB 3, uma vez que, por uma série de motivos, é muito freqüente na prática clínica do cirurgião-dentista a utilização de resina e adesivo de marcas comerciais diferentes. Utilizou-se um dispositivo constituído de base e matriz, as quais, quando justapostas, apresentavam uma cavidade em forma de halteres que recebeu a resina composta. Inicialmente, confeccionaram-se 45 meio-espécimes de cada resina. Após uma semana armazenados em água destilada a 37ºC, os meio-espécimes foram reposicionados na matriz para confecção da segunda metade e divididos em grupos de modo a combinar cada resina com cada um dos três adesivos. Armazenaram-se os espécimes em água destilada a 37ºC por 7 dias e procedeu-se ao teste de tração na máquina Kratos. Concluiu-se que: de forma geral, as interações entre as resinas e os adesivos testados mostraram-se compatíveis; a combinação AP.H/XR-Bond apresentou a maior discrepância, pois a resistência à tração foi estatisticamente inferior à associação original proposta pelo fabricante; as demais combinações entre os adesivos e as resinas testadas apresentaram resistência à tração estatisticamente semelhantes ou superiores à associação recomendada pelo fabricante

The influence of surface treatment on the implant roughness pattern

An important parameter for the clinical success of dental implants is the formation of direct contact between the implant and surrounding bone, whose quality is directly influenced by the implant surface roughness. A screw-shaped design and a surface with an average roughness of Sa of 1-2 µm showed a better result. The combination of blasting and etching has been a commonly used surface treatment technique. The versatility of this type of treatment allows for a wide variation in the procedures in order to obtain the desired roughness. OBJECTIVES: To compare the roughness values and morphological characteristics of 04 brands of implants, using the same type of surface treatment. In addition, to compare the results among brands, in order to assess whether the type of treatment determines the values and the characteristics of implant surface roughness. MATERIAL AND METHODS: Three implants were purchased directly from each selected company in the market, i.e., 03 Brazilian companies (Biomet 3i of Brazil, Neodent and Titaniumfix) and 01 Korean company (Oneplant). The quantitative or numerical characterization of the roughness was performed using an interferometer. The qualitative analysis of the surface topography obtained with the treatment was analyzed using scanning electron microscopy images. RESULTS: The evaluated implants showed a significant variation in roughness values: Sa for Oneplant was 1.01 µm; Titaniumfix reached 0.90 µm; implants from Neodent 0.67 µm, and Biomet 3i of Brazil 0.53 µm. Moreover, the SEM images showed very different patterns for the surfaces examined. CONCCLUSIONS: The surface treatment alone is not able to determine the roughness values and characteristics

Avaliação clínica de inlays e onlays confeccionadas com dois tipos de cerâmica, após 06 meses

The aim of the present study was to evaluate the clinical performance of two types of ceramics: a slurry-powder ceramic (Duceram Plus, Degussa) - D and a hot-pressed leucite-based glass-ceramic (IPS Empress, Ivoclar Vivadent) - IPS. Eighty-six restorations, 44 IPS and 42 D, were made by one operator. A total of 33 onlays and 53 inlays on twenty-seven premolars and 59 molars were cemented in 35 patients of both sexes, mean age 35 years. All restorations were cemented with the dual-resin cement (Variolink, Ivoclar-Vivadent) under rubber dam and were evaluated at the baseline and after six months, using the modified U.S.P.H.S. criteria for postoperative sensitivity, secondary caries, fracture, color match, marginal discoloration, marginal integrity and surface texture. Additionally radiographs and intraoral photographs were carried out. At baseline 86 restorations were analyzed and all of them received Alfa rating, except for the following that received Bravo rating for postoperative sensitivity - IPS (2.27%); D (7.14%); for color match - IPS (2.27%); D (2.38%) and for surface texture - IPS (2.27%); D (11.90%). After 6 months 100% of the restorations were analyzed and the following received Bravo rating: color match - IPS (4.55%) and D (9.52%); surface texture - IPS (2.27%) and D (11.9%); marginal discoloration - IPS (6.82%) and D (4.76%) and marginal integrity - IPS (4.55%) and D (7.14%). The results were submitted to the Fisher and McNemar Statistical Tests. No significant differences were noticed between the two ceramics. Both ceramics demonstrated satisfactory clinical performance after six months.Este trabalho se propôs a avaliar a performance clínica de dois tipos de cerâmica: IPS Empress, Ivoclar-Vivadent - IPS e Duceram Plus, Degussa - D. Foram realizadas 86 restaurações por apenas um operador, sendo 44 IPS e 42 D. Vinte e sete pré-molares e 59 molares, num total de 33 onlays e 53 inlays, foram cimentadas em 35 pacientes de ambos os sexos, com idade média de 35 anos. A cimentação das restaurações foi realizada com cimento resinoso dual (Variolink, Ivoclar-Vivadent) sob isolamento absoluto e avaliadas no baseline e após 06 meses, mediante o critério U.S.P.H.S. modificado, quanto à sensibilidade pulpar, reincidência de cárie, fratura, reprodução de cor, descoloração marginal, integridade marginal e textura superficial. Adicionalmente foram realizadas radiografias e fotografias. No baseline foi obtida a classificação Bravo nos itens sensibilidade pulpar - IPS (2,27%); D (7,14%); reprodução de cor - IPS (2,27%); D (2,38%) e textura superficial - IPS (2,27%); D (11,90%). Após 06 meses foram analisadas as 86 restaurações, nas quais foi constatada a classificação Bravo para os itens reprodução de cor - IPS (6,82%); D (2,38%); textura superficial - IPS (2,27%); D (9,52%); descoloração marginal - IPS (6,82%); D (4,76%) e integridade de superfície- IPS (4,55%); D (7,14%). Os resultados obtidos foram submetidos ao Teste Estatístico de Fisher e McNemar. Não houve diferença estatisticamente significante entre as cerâmicas. Pode-se concluir que os dois tipos de cerâmica demonstraram uma performance clínica satisfatória após 06 meses

Analysis of the distribution of stress and deformation in single implant-supported prosthetic units in implants of different diameters

Abstract Introduction When stress and strain levels in the bone-implant system exceed It's capacity, a mechanical fatigue occurs, resulting in collapse and loss of osseointegration. Objective Analyze biomechanical behavior in single implant-supported prosthesis with implants of different diameters in the posterior mandible. Material and method Three different finite element models of Cone-Morse implants with the same height were created, varying the diameter (3.3 mm, 4.1 mm and 4.8 mm). The mandibular first molar area was the location of the implant, with It´s component and overlying prosthetic crown. The jawbone was composed of cortical and cancellous bone. Refined mesh of 0.5 mm was created in the critical interfaces to be analyzed. The loading of the models was performed at the point of occlusal contact with an occlusal load of 400 N. Result Maximum stress and strain occurred in the cervical regions of the implants in all groups, either in the implants or in components as well as in the analysis of cortical bone. The greater the diameter, the lower the stress and strain found in the implant. The 3.3 mm group had the highest strain in peri-implant cortical bone, and the 4.1 mm group had the smallest deformation, significantly lower than in the 4.8 mm group. Conclusion Although the biggest implant diameter (4.8 mm) appears to have lower values of stress and strain, the group of intermediate implant diameter (4.1 mm) showed less deformation rate in the cortical peri-implant bone. Therefore it is concluded that the 4.1 mm implant platform presented a more biomechanically effective peri-implant bone maintenance

Analysis of the distribution of stress and deformation in single implant-supported prosthetic units in implants of different diameters

Abstract Introduction When stress and strain levels in the bone-implant system exceed It's capacity, a mechanical fatigue occurs, resulting in collapse and loss of osseointegration. Objective Analyze biomechanical behavior in single implant-supported prosthesis with implants of different diameters in the posterior mandible. Material and method Three different finite element models of Cone-Morse implants with the same height were created, varying the diameter (3.3 mm, 4.1 mm and 4.8 mm). The mandibular first molar area was the location of the implant, with It´s component and overlying prosthetic crown. The jawbone was composed of cortical and cancellous bone. Refined mesh of 0.5 mm was created in the critical interfaces to be analyzed. The loading of the models was performed at the point of occlusal contact with an occlusal load of 400 N. Result Maximum stress and strain occurred in the cervical regions of the implants in all groups, either in the implants or in components as well as in the analysis of cortical bone. The greater the diameter, the lower the stress and strain found in the implant. The 3.3 mm group had the highest strain in peri-implant cortical bone, and the 4.1 mm group had the smallest deformation, significantly lower than in the 4.8 mm group. Conclusion Although the biggest implant diameter (4.8 mm) appears to have lower values of stress and strain, the group of intermediate implant diameter (4.1 mm) showed less deformation rate in the cortical peri-implant bone. Therefore it is concluded that the 4.1 mm implant platform presented a more biomechanically effective peri-implant bone maintenance