Assessment of stress/strain in dental implants and abutments of alternative materials compared to conventional titanium alloy-3D non-linear finite element analysis.

The aim of this study was to assess the stress/strain in dental implant/abutments with alternative materials, in implants with different microgeometry, through finite element analysis (FEA). Three-dimensional models were created to simulate the clinical situation of replacement of a maxillary central incisor with implants, in a type III bone, with a provisional single crown, loaded with 100 N in a perpendicular direction. The FEA parameters studied were: implant materials-titanium, porous titanium, titanium-zirconia, zirconia, reinforced fiberglass composite (RFC), and polyetheretherketone (PEEK); and abutment materials-titanium, zirconia, RFC, and PEEK; implant macrogeometry-tapered of trapezoidal threads (TTT) and cylindrical of triangular threads (CTT) (ø4.3 mm × 11 mm). Microstrain, von Mises, shear, and maximum and minimum principal stresses in the structures and in peri-implant bone were compared. There was increased stress and strain in peri-implant bone tissue caused by implants of materials with lower elastic modulus (mainly for PEEK and RFC). They also presented higher concentration of stresses in the implant itself (especially RFC). Zirconia implants led to lower stress and strains in peri-implant bone tissue. Less rigid abutments (RFC and PEEK) associated with titanium implants led to higher stress in the implant and in peri-implant bone tissue. The TTT macrogeometry showed a higher stress concentration in the implant and peri-implant bone tissue. The stress/strain in peri-implant bone tissue and implant structures were affected by the material used, where reduced values were caused by stiffer materials. Lower stress/strain values were obtained with cylindrical implants of triangular treads.

Influence of Implant Inclination and Prosthetic Abutment Type on the Biomechanics of Implant-Supported Fixed Partial Dentures.

Obtaining parallelism during implant placement is often difficult, leading to inclination of implants. The present study evaluated the stress distribution in 3-unit fixed partial dentures supported by 2 implants with different inclinations and prosthetic abutments. Universal castable long abutments (UCLAs) or tapered abutments were used considering 17° of implant angulation in different directions (mesial, distal, buccal, or lingual). To do so, 3-dimensional finite element models were built and exported to specific analysis software. Forces were applied to the functional cusps. Data were obtained with regard to the maximum principal and von Mises stresses (in MPa). No relevant differences were observed in the stress values in the cortical and cancellous bone nor in the prosthesis with UCLA or tapered abutments. However, a relevant stress reduction in the prosthetic screws of the tilted implant was observed when using UCLA abutments. According to the obtained results, it is possible to suggest that both UCLA or tapered abutments can be used for 3-unit fixed partial dentures when 1 of the implants is tilted. UCLA abutment might lead to less biomechanical problems related to screw loosening or fracture.

Eficácia e segurança da sedação consciente com óxido nitroso no tratamento pediátrico odontológico: uma revisão de estudos clínicos / Effectiveness and safety of nitrous oxide in pediatric dentistry: a review of clinical studies

Objetivo: analisar a utilização da sedação consciente com óxido nitroso/oxigênio, sua eficácia e segurança durante o tratamento pediátrico. Métodos: foi realizada busca nas bases de dados do Pubmed/Medline e manual nas principais revistas da área. Todavia, não avaliando somente eficácia e segurança, mas também, comparando a sedação com óxido nitroso com demais técnicas tradicionais, sendo usada como complemento de técnicas ou analisando diferenças na aplicação do óxido nitroso. Resultados: os estudos demonstraram que a sedação consciente foi eficaz no tratamento odontopediátrico e segura quando realizada por profissionais treinados para exercer esta aplicação em determinados pacientes, sendo estes corretamente avaliados quanto a estarem aptos a receber a sedação. Nos demais resultados, foi obtido bom atendimento, com diminuição do choro e estado de alerta da criança, ao combinar, por exemplo, manejo comportamental com óxido nitroso, o medo diminuiu ainda mais, entretanto, não foi apresentado efeitos analgésicos na maioria dos casos e não houve diminuição no tempo de consulta com o uso do óxido nitroso, embora, também não requereu maior número de seções. Conclusão: A sedação consciente com oxido nitroso foi uma técnica segura e eficaz para utilização em crianças, desde que o profissional seja habilitado e a criança apta para passar pelo processo de sedação inalatória(AU)

Objective: to analyze the use of conscious sedation with nitrous oxide / oxygen, its efficacy and safety during pediatric treatment. Methods: we searched the Pubmed/Medline databases and searched the main journals in the area. However, not only evaluating efficacy and safety, but also comparing sedation with nitrous oxide with other traditional techniques, being used as a complement to techniques or analyzing differences in the application of nitrous oxide. Results: the studies demonstrated that conscious sedation was effective in pediatric dentistry and safe when performed by professionals trained to exercise this application in certain patients, being correctly evaluated in terms of being able to receive sedation. In the other results, good care was obtained, with decreased crying and alertness of the child, by combining, for example, behavioral management with nitrous oxide, fear decreased even more, however, no analgesic effects were present in most cases and there was no decrease in the time of consultation with the use of nitrous oxide, although it did not require a greater number of sections. Conclusion: Conscious sedation with nitrous oxide was a safe and effective technique for use in children, provided that the professional is qualified and the child is able to undergo the process of inhalation sedation(AU)