Micro-leakage at the implant-abutment interface with different tightening torques in vitro

OBJECTIVES: This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques. MATERIAL AND METHODS: A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (

Avaliação das coroas de dissilicato de lítio obtidas por sistemas CAD/CAM de consultório e pela técnica de prensagem a quente por meio da adaptação marginal utilizando a micro-tomografia computadorizada

Objectives: The current study evaluated the marginal fit of lithium disilicate crowns fabricated by different chairside CAD/CAM systems (CEREC and E4D) and hot-pressed technique using micro-CT. Methods: A human mandibular premolar was mounted with its adjacent teeth on a typodont model, and prepared for an all-ceramic crown. In the first group, the control group P, five restorations were fabricated from lithium disilicate glass ceramics, using a combination of the lost-wax and hot-pressed technique. Five different impressions, designs and crowns were made for each CAD/CAM system: group C, scanned with CEREC, using a thin layer of titanium dioxide powder, and group E, scanned with E4D, without powdering. Each crown was fixed. All specimens were scanned using a micro-CT to obtain images for marginal gap measurements. Fifty-two measurements were done for each specimen (n=260). Three independent examiners were calibrated prior to the measurements of the marginal gaps. Results: Considering the percentage of vertical marginal gap up to 75 μm, the results were: P 83.85%, C 83.85% e E 65%. The percentages of horizontal measurements with overextension of the crowns were: P 19.61%, C 21.16%, and E 23.85% Conclusions: Within the limitations of this study, it was concluded that vertical misfit below 75 μm, the group had 35% of the E4D values greater than desired, against 16.25% of the groups Pressed and CEREC, apparently having worse performance. As the horizontal misfit three techniques had the same performance with 20% of overextension areas, suggesting that all techniques can be improved.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorMestre em OdontologiaObjetivos: O presente estudo avaliou coroas de dissilicato de lítio fabricadas por diferentes sistemas CAD/CAM de consultório (CEREC e E4D) e pela técnica de prensagem à quente pela análise da adaptação marginal vertical e horizontal por meio do micro-CT. Métodos: Um pré-molar inferior humano anteriormente extraído foi montado com os dentes adjacentes em um modelo Typodont e preparados para receber uma coroa total cerâmica. No primeiro grupo, o grupo controle P, cinco restaurações foram fabricados a partir de cerâmica de dissilicato de lítio, utilizando uma combinação da técnica de cera perdida e prensada a quente. Cinco diferentes moldagens digitais, desenhos e coroas foram feitos para cada sistema CAD / CAM: grupo C, CEREC, os modelos foram escaneados usando uma fina camada de pó de dióxido de titânio, e grupo E, E4D, o escaneamento foi realizado sem pulverização. Cada coroa foi fixada no dente e foram escaneadas utilizando um micro-CT para obter imagens que possibilitem as medições da desadaptação marginal. Cinquenta e duas medidas foram feitas para cada amostra resultando em 260 medidas por grupo. Três examinadores independentes foram calibrados antes de realizar as medidas dos espaços marginais. Resultados: Considerando a porcentagem de desadaptação vertical, inferior a 75 μm, grupos P e C apresentaram 83,85%, e grupo E 65%. As porcentagens de medidas horizontais com sobrextensão foram: grupo P 19,61%, grupo C 21,16%, e grupo E 23,85%. Conclusões: Dentro das limitações deste estudo, concluiu-se quanto à desadaptação vertical que analisando os valores abaixo de 75 μm, o grupo E4D apresentou 35% dos valores maiores que o desejado, contra 16,25% dos grupos Prensado e CEREC, tendo aparentemente pior desempenho. Quanto às desadaptações horizontais as três técnicas tiveram o mesmo desempenho, com cerca de 20% das áreas em sobre-extensão, sugerindo que todas técnicas possam ser melhoradas

Indirect unitary restorations obtained by CAD / CAM chairside technology: laboratory evaluation

CAD / CAM system in dentistry is an alternative to obtain all-ceramic crowns. The marginal adaptation of these crowns depends on the correct use of the scanner, software and milling machine. The type of ceramic material selected CAD / CAM crowns could influence the marginal adaptation. It is known that the selection of the ceramic material is carried out considering physical and optical properties and a region to be rehabilitated, but identifying the materials that bring the best fit may be another factor (Chapter 1). In addition, new data acquisition technologies of different scanners could minimize the marginal adaptation (Chapter 2). Finally, the range of the luting space parameters determines the degree of marginal and internal seating of the crown. Consequently, an internal fit is correlated to the space occupied by the resin cement and a variation could influence a quantity of cement and a crown resistance. In addition, the ceramics thickness could attenuate the irradiation and the wavelength, which alter the polymerization and deformation of the crown (Chapter 3). Therefore, the balance between the use of scanner technology, software, resin resin thickness and ceramic material should be considered to have a crowns with good marginal and internal fit.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTese (Doutorado)O sistema CAD/CAM na Odontologia é uma alternativa para a confecção de coroa totais cerâmicas. A adaptação marginal destas coroas depende da correta utilização do escâner, software e fresadora. O tipo do material cerâmico selecionado para a fabricação das coroas no sistema CAD/CAM, pode influenciar na qualidade final da adaptação marginal. Sabe -se que a seleção do material cerâmico é realizada considerando as propriedades mecânicas físicas e óticas e a região a ser reabilitada, porém identificar materiais que trazem melhor adaptação pode ser mais um fator importante nesta seleção (Capitulo 1). Além disso, novas tecnologias de aquisição de dados de diferentes escâneres podem impactar na adaptação marginal e o uso de técnicas devem ser estudadas para minimizar esta influência (Capitulo 2). Por fim, a variação dos parâmetros definidos no software, como o espaço de cimentação, determina a precisão de assentamento marginal e interno da coroa. Por consequência, a adaptação interna está correlacionada ao espaço ocupado pelo cimento resinoso e a variação deste pode influenciar a quantidade de cimento e fragilizar a restauração devido a contração de polimerização e deformação da coroa. Além disso, fatores relacionados com a espessura das cerâmicas, podem atenuar a irradiância e o comprimento de onda, que altera o padrão de polimerização e deformação da coroa (Capítulo 3). Portanto, o equilíbrio entre a utilização adequada da tecnologia do escâner, parâmetros do software, espessura do cimento resinoso e do material cerâmico devem ser consideradas para se obter boa adaptação marginal e interna das coroas

Micro-leakage at the implant-abutment interface with different tightening torques in vitro

OBJECTIVES: This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques. MATERIAL AND METHODS: A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.5: 0.5 µL; V1.0: 1.0 µL e V1.5: 1.5 µL, and tightened to the manufacturer's recommended torque. The second phase of this experiment used 27 assemblies that were similar to those used in the first phase. These samples were inoculated with 0.5 µL of bacterial suspension and divided into three groups (n=9). T10: 10 Ncm; T20: 20 Ncm and T32: 32 Ncm. The samples were evaluated according to the turbidity of the broth every 24 hours for 14 days, and the bacteria viability was tested after that period. The statistical evaluation was conducted by Kruskal-Wallis testing (p<.05). RESULTS: During the first phase, groups V1.0 and V1.5 was presented with bacterial contamination in all samples after 24 h. During the second phase, two samples from group T10 and one from T20 presented positive results for bacterial contamination. Different amounts of bacterial solution led to overflow and contamination during the first 24 h of the experiment. The tightening torques did not statistically affect the microleakage in the assemblies. However, the group that was tightened to 32 Ncm torque did not show any bacterial contamination. CONCLUSION: After 14 days of experimentation, the bacteria were proven to remain viable inside the implant internal cavity

Anus neoplasm: study of a case series

Anus neoplasm accounts for 2 to 4% of colorectal tumors, being more prevalent around the seventh and the eighth decades. Females are mostly affected, and the ratio is 3:1. Its increased prevalence amongst the population in the past years is probably related to the higher number of people that are affected by sexually transmitted diseases, mainly human papillomavirus (types 16 and 18, mostly) and/or the human immunodeficiency virus. Diagnosis is based on clinical findings and anatomopathological tests. The treatment of choice is radiochemotherapy, and the rescue surgery with abdominoperineal resection is used for recurrence and persistence cases. A retrospective and prospective longitudinal observational study was performed with 11 patients diagnosed with anal neoplasm from 2004 to 2010. Six (54.5%) were females and five (45.5%) were males. The incidence was higher in the sixth decade, at the mean age of 54.45 years. The most frequent histological type observed was the epidermoid carcinoma, and the most frequent cell differentiation type was the moderately differentiated. Chemotharapy associated with radiotherapy was used in 81.9% of the patients, and abdominoperineal resection was necessary as a rescue surgery in 18.2% of the patients

Bacterial microleakage at the implant-abutment interface in Morse taper implants

AIM: To evaluate the microleakage at the implant-abutment (I-A) interface of Morse tapered implants inoculated with different volumes of bacterial suspension.METHODS: Morse tapered I-A sets were selected and divided in two groups depending on the type of abutment: passing screw (PS) and solid (S), and then subdivided into four subgroups (n=6) according to the suspension volume: PS1: 0.1 µL; PS3: 0.3 µL; PS5: 0.5 µL; PS7: 0.7 µL; S1: 0.1 µL; S3: 0.>3 µL; S5: 0.5 µL and S7: 0.7 µL. A control test was performed to verify the presence of external contamination during the inoculation and the implants were incubated for microbiological analysis. The microleakage was evaluated every 24 h for 7 days by the clarity of solution. After this period, the implants were disassembled for confirmation of bacterial viability.RESULTS: All the specimens with 0.7 µL and one sample of S5 presented turbidity in the control test indicating external contamination, and were excluded from the study. After 7 days of observation, none of the specimens presented positive results for microleakage and the bacterial viability was confirmed in all specimens. The 0.1 µL and 0.3 µL volumes did not present bacterial microleakage, meaning that these volumes may be inadequate for analysis.CONCLUSIONS: None of the sets evaluated showed bacterial microleakage at the I-A interface and the volume of 0.7 µL exceeded the internal capacity of the implants

Bacterial microleakage at the implant-abutment interface in Morse taper implants

evaluate the microleakage at the implant-abutment (I-A) interface of Morse tapered implants inoculated with different volumes of bacterial suspension. Methods: Morse tapered I-A sets were selected and divided in two groups depending on the type of abutment: passing screw (PS) and solid (S), and then subdivided into four subgroups (n=6) according to the suspension volume: PS1: 0.1 µL; PS3: 0.3 µL; PS5: 0.5 µL; PS7: 0.7 µL; S1: 0.1 µL; S3: 0.3 µL; S5: 0.5 µL and S7: 0.7 µL. A control test was performed to verify the presence of external contamination during the inoculation and the implants were incubated for microbiological analysis. The microleakage was evaluated every 24 h for 7 days by the clarity of solution. After this period, the implants were disassembled for confirmation of bacterial viability. Results: All the specimens with 0.7 µL and one sample of S5 presented turbidity in the control test indicating external contamination, and were excluded from the study. After 7 days of observation, none of the specimens presented positive results for microleakage and the bacterial viability was confirmed in all specimens. The 0.1 µL and 0.3 µL volumes did not present bacterial microleakage, meaning that these volumes may be inadequate for analysis. Conclusions: None of the sets evaluated showed bacterial microleakage at the I-A interface and the volume of 0.7 µL exceeded the internal capacity of the implants