Resumo O objetivo deste estudo foi avaliar a perda óssea peri-implantar de implantes Hexágono Externo (HE) e Cone Morse (CM) em usuários de sobredentaduras mandibulares com carga imediata por um período de acompanhamento de 1 ano. Este é um ensaio clínico controlado não randomizado que inclui 18 CM e 22 HE. Radiografias periapicais foram obtidas na instalação das sobredentaduras e 1 ano após. A perda óssea peri-implante foi avaliada através da digitalização e análise das radiografias no software Corel DRAW X7. Para tal, a medição foi feita da plataforma dos implantes até a crista óssea nas faces mesiais e distais de cada implante. Os resultados mostraram alta taxa de sucesso nos grupos HE (100%) e CM (94,4%). Para os níveis ósseos peri-implantes, foi encontrada diferença significativa entre os grupos (p = 0,032) e maior perda óssea foi observada no grupo HE. Em média, a perda óssea foi de 0,85 mm (±0,82) para HE e de 0,10 mm (±1,0) para CM. Concluiu-se que uma maior perda óssea ocorreu no grupo HE em comparação com o grupo CM após um acompanhamento de 1 ano.

Abstract The aim of this study was to evaluate the peri-implant bone loss of External Hexagon (EH) and Morse Taper (MT) implants in patients wearing immediately loaded mandibular overdentures during a 1-year follow-up. This is a non-randomized controlled clinical trial including 18 MT and 22 EH implants. Periapical radiographs were taken after overdentures insertion and following 1 year. The peri-implant bone loss was assessed through digitalization and analysis of the radiographs in the software Corel DRAW X7. For this, measurement from implant platform to residual ridge at mesial and distal surfaces of each implant was conducted. The results showed high success rate in the groups EH (100%) and MT (94.4%). For peri-implant bone levels, it was found significant difference between the groups (p=0.032) and greater bone loss was observed in the group EH. In general, bone loss was 0.85mm (±0.82) for EH and 0.10mm (±1.0) for MT. It was concluded that greater bone loss occurred in the group EH in comparison to the group MT after a 1-year follow-up.

This systematic review evaluated the influence played by the number of implants on the results of rehabilitation treatment with mandibular overdentures on 2 or 4 implants. The literature search was conducted using PubMed, Embase and Cochrane databases. Specific terms were used in performing a search from January 1980 to January 2013. The search strategy was applied by two reviewers who extracted the data and compared the results. Discrepancies were resolved by discussion. Great heterogeneity was seen among the selected studies, in regard to survival rates, prosthesis failure and function rates. A medium degree of quality and methodological consistency was found in one study, and no studies showed a high degree. When considering the prosthesis success rate for 2 implants, there was a variation of 23% to 100%. However, when considering the survival rate, the result was 92% to 100%. For 4 implants, prosthesis survival rates showed less variation, i.e., 97.7% to 100%. Ball attachments were the most common type of abutment for 2 implants; however, there was a higher prevalence of bar abutments for 4 implants. Rehabilitations with 2 implants showed more complications and required more maintenance according to the connection type. Given the limitations of this review, mandibular overdentures with 4 implants showed better results with respect to survival and success rates, especially those with a bar connection. Further studies comparing these two treatment types are necessary to improve the scientific evidence in this area.