Implant design evolved alongside the development of implant therapy. The purpose of this finite element analysis (FEA) study was to analyze the influence of different implant designs on the stress and strain distribution to the implants and surrounding bone. Three implant designs with the same length and diameter were used. The three-dimensional geometry of the bone was simulated with a cortical bone of three different thicknesses and two medullar bone densities: low density (150 Hounsfield units) and high density (850 Hounsfield units). A 30° oblique load of 150 N was applied to the implant restoration. Displacement and stress (von Mises) results were obtained for bone and dental implants. The strain and stress distributions to the bone were higher for the tissue-level implant for all types of bone. The maximum principal strain and stress decreased with an increase in cortical bone thickness for both cancellous bone densities. The distribution of the load was concentrated at the coronal portion of the bone and implants. All implants showed a good distribution of forces for non-axial loads, with higher forces concentrated at the crestal region of the bone–implant interface. Decrease in medullar bone density negatively affects the strain and stress produced by the implants.

The aim of this study was to evaluate the effects of different implant sites an under-preparation sequence associated with two different implant designs on implant primary stability measured by two parameters: insertion torque (IT) and implant stability quotient (ISQ). It used two different implants: one cylindrical as a control and another one with a tapered design. The implants were inserted in type III fresh humid bovine bone and four drilling sequences were used: one control, the one proposed by the implant company (P1), and three different undersized (P2, P3 and P4). P2 was the same as P1 without the cortical drill, P3 was without the last pilot drill and P4 was without both of them. The sample size was n = 40 for each of the eight groups. Final IT was measured with a torquemeter and the ISQ was measured with Penguin resonance frequency analysis. Results showed that both ISQ and IT have a tendency to increase as the preparation technique reduces the implant site diameter when compared with the standard preparation, P1. The preparations without cortical drill, P2 and P4, showed the best results when compared with the ones with a cortical drill. Tapered implants always showed higher or the same ISQ and IT values when compared with the cylindrical implants. Giving the limitations of this study, it can be concluded that reducing implant preparation can increase IT and ISQ values. Removing the cortical drill and the use of a tapered design implant are also effective methods of increasing primary implant stability.

Objective: The main aim of this study was to assess the clinic atmosphere quality regarding the Index of Air Microbial contamination (IMA), according to dental aerosols bacterial counts, when different dentistry procedures are performed. Material and methods The aerosols generated by dentistry and endodontic procedures were analyzed in 26 dental units of the dental clinic. Blood agar plates (n = 244) were incubated at 37 °C/48 h and the colony forming units (CFU) were calculated. All statistical analysis methods were conducted using the SPSS^® vs.17.0 software (SPSS Inc., IL, Chicago, USA), using α = 0.05 for the comparison tests used (non parametric tests of Mann–Whitney and Wilcoxon). Results: The IMA median value in the dental clinic was of 10.4 CFU/dm²/h. Aerosols’ CFU counts were significantly higher at 0.5 m and during endodontic treatments. Longer treatment times were associated with higher CFU counts both in dentistry and endodontic procedures. The use and time of turbine use did not significantly affect the CFU counts. Micrococcus sp., Staphylococcus sp. and Streptococcus sp. were identified with presumptive tests after isolation of representative colonies. Conclusion: Considering the IMA, the dental clinic atmosphere quality was found to be good. Objetivo: O objetivo principal deste trabalho foi determinar a qualidade do ar da clínica utilizando o Index of Air Microbial contamination (IMA), mediante utilização de contagens bacterianas em aerossóis dentários produzidos durante a realização de diferentes procedimentos dentários. Material e métodos Foram analisados aerossóis gerados por procedimentos de dentística e endodontia em 26 unidades dentárias distribuídas pela clínica de medicina dentária. As placas de agar de sangue (n = 244) foram incubadas a 37 °C/48 h e foram calculadas a unidades formadoras de colónias (UFC). A análise estatística foi realizada recorrendo ao software SPSS^® vs. 17.0 software, utilizando α = 0.05 em todos os testes de comparação estatística realizados (testes não paramétricos de Mann–Whitney e de Wilcoxon). Resultados: A mediana do IMA na clínica de medicina dentária foi 10,4 UFC/dm²/h. As contagens de UFC nos aerossóis foram significativamente superiores na distância 0,5 m e durante tratamentos endodônticos. Tratamentos mais longos estão associados a contagens mais elevadas de UFC, tanto para procedimentos de dentística como de endodontia. A utilização e tempo de utilização de turbina não afetou significativamente as contagens de UFC. Após isolamento de colónias representativas e utilizando de testes presumptivos, foi possível identificar Micrococcus sp., Staphylococcus sp. e Streptococcus sp. Conclusão: A qualidade do ar na clínica de medicina dentária, utilizando o IMA, foi considerada como boa.