Influence of connector cross-sectional geometry on the load-bearing capacity under fatigue of implant-supported zirconia fixed partial prosthesis.

STATEMENT OF PROBLEM: Zirconia has been reported to be suitable for multiunit monolithic restorations. However, as the connector region is the weakest part of the system, studies are needed to determine the optimal connector geometry. PURPOSE: The purpose of this in vitro study was to evaluate the load-bearing capacity under fatigue of implant-supported fixed partial prostheses made of monolithic zirconia with different connector cross-sectional geometries. MATERIAL AND METHODS: Three-unit monolithic fixed partial prostheses (from mandibular second premolar to the second molar) were fabricated in zirconia (Zenostar T) by computer-aided design and computer-aided manufacture (CAD-CAM). Different connector cross-sectional geometries, with an area of 9 mm2, were tested (n=10): round, square with rounded angles, or trapezoid with rounded angles. The prostheses were screwed over 2 implants and inserted into acrylic resin bases. The specimens were submitted to a mechanical fatigue test until failure, with load applied to the pontic using the stepwise stress methodology (initial load of 100 N for 5000 cycles, followed by an increase to 200 N for 20 000 cycles, with a subsequent increase of 50 N each step). For data analysis, fatigue failure load (FFL) and cycles for fatigue failure (CFF) were recorded. Failed structures were analyzed by fractography. The Kaplan-Meier test followed by a log-rank Mantel-Cox post hoc test was used to analyze FFL and CFF (α=.05). Weibull analysis was also performed. RESULTS: The round (1065 N) and trapezoid (1010 N) groups presented higher FFL values than the square one (870 N) (P≤.05). For CFF, the round connector (358 777) was better than the square (280 310) (P=.006), and the trapezoid (337 773) was statistically similar to both (P>.05). No difference among groups was observed in Weibull modulus either for CFF or FFL data. All failures were catastrophic, originating at the base of the connector and propagating toward the occlusal surface of the pontic (region under loading). CONCLUSIONS: The connector cross-sectional geometry significantly influenced the mechanical fatigue performance of implant-supported fixed partial prostheses made of monolithic zirconia.

Use of platelet concentrates in oral surgery of patients with osteonecrosis: a scoping review.

The objective of this study was to map, through a scoping review, the evidence available in the literature on the use of platelet concentrates in compromised patients undergoing oral surgeries. Searches were performed in electronic databases for clinical studies with compromised patients undergoing oral surgery who used platelet concentrates. Only studies published in English were included. Two independent researchers carried out the selection of studies. The study design and objective, surgical procedure and platelet concentrate used, systemic involvement, analyzed outcome, and main results were extracted. A descriptive analysis of the data was performed. Twenty-two studies met the eligibility criteria and were included. Case series was the most frequent study design among the included studies (41.0%). In terms of systemic disability, 19 studies reported patients with cancer and related to surgical treatment 16 studies reported patients underwent treatment for osteonecrosis related to the use of the drug. The most used platelet concentrate was pure platelet-rich fibrin (P-PRF). In general, most studies recommend the use of platelet concentrates. Thus, the results of this study suggest that the evidence related to the use of platelet concentrates in compromised patients when undergoing oral surgeries is still initial. Also, most studies assessed the use of platelet concentrates in patients with osteonecrosis.

Use of platelet concentrates in oral surgery of patients with osteonecrosis: a scoping review

Abstract The objective of this study was to map, through a scoping review, the evidence available in the literature on the use of platelet concentrates in compromised patients undergoing oral surgeries. Searches were performed in electronic databases for clinical studies with compromised patients undergoing oral surgery who used platelet concentrates. Only studies published in English were included. Two independent researchers carried out the selection of studies. The study design and objective, surgical procedure and platelet concentrate used, systemic involvement, analyzed outcome, and main results were extracted. A descriptive analysis of the data was performed. Twenty-two studies met the eligibility criteria and were included. Case series was the most frequent study design among the included studies (41.0%). In terms of systemic disability, 19 studies reported patients with cancer and related to surgical treatment 16 studies reported patients underwent treatment for osteonecrosis related to the use of the drug. The most used platelet concentrate was pure platelet-rich fibrin (P-PRF). In general, most studies recommend the use of platelet concentrates. Thus, the results of this study suggest that the evidence related to the use of platelet concentrates in compromised patients when undergoing oral surgeries is still initial. Also, most studies assessed the use of platelet concentrates in patients with osteonecrosis.

Resumo O objetivo do estudo foi mapear, através de uma revisão de escopo, as evidências disponíveis na literatura sobre o uso de agregrantes plaquetários em pacientes comprometidos e que realizaram cirurgias odontológicas. Pesquisas foram realizadas em bases de dados por estudos clínicos com pacientes comprometidos que realizaram cirurgia odontológica e usaram agragantes plaquetários. Apenas estudos em inglês foram incluídos. Dois pesquisadores independentes realizaram a seleção dos estudos. Os seguintes dados foram extraídos: desenho do estudo, objetivo, procedimento cirúrgico, agregante plaquetário usado, envolvimento sistêmico, desfecho analisado e principais resultados. Uma análise descritiva dos dados foi realizada. Vinte e dois estudos preencheram os critérios de elegibilidade e foram incluídos. Série de casos foi o desenho de estudo mais frequente entre os estudos incluídos (41,0%). Em relação ao comprometimento sistêmico, 19 estudos reportaram pacientes com câncer e em relação ao tratamento cirúrgico, 16 estudos reportaram pacientes que realizavam tratamento para osteonecrose relacionada ao uso de medicamentos. O agregante mais utilizado foi o plasma rico em fribina (P-PRF). Em geral, maioria dos estudos recomendou o uso dos agregantes plaquetários. Assim, os resultados desse estudo sugerem que a evidência relacionada ao uso de agregantes plaquetários em pacientes comprometidos que realizam cirurgia odontológica é ainda inicial. Ainda, a maioria dos estudos avaliaram o uso de agregantes plaquetários em pacientes com osteonecrose.