Correlation between bond strength and nanomechanical properties of adhesive interface.

OBJECTIVES: The aims of this study were to evaluate the nanohardness and Young's modulus of the adhesive-dentin interface and to correlate them with the microtensile bond strength (µTBS) after storage in water for 24 h and 6 months. METHODS: Eighty human third molar teeth were bonded to composite resin with the Adper Scotchbond Multipurpose (SBMP), Adper Single Bond 2 (SB2), Clearfil SE Bond (CSE) or Clearfil S3 Bond (CS3) adhesive systems and stored in water for 24 h and 6 months. Three bonded teeth were selected for each group for nanoindentation methodology to obtain the nanohardness and modulus values (n = 3), while seven bonded teeth each group were used for µTBS (n = 7). Data were analyzed by two-way ANOVA and Tukey's test (α = 0.05). Spearman correlation between nanohardness and modulus and µTBS values was also calculated. RESULTS: Nanohardness and Young's modulus values for the dentin and hybrid layer were not significantly different regardless of the adhesive system or water storage periods (p > 0.05). Nanohardness and Young's modulus values for the adhesive layer were significantly higher for SB2 than for SBMP, CSE, and CS3 systems in both water storage periods. The µTBS values for SBMP and CSE were significantly higher than for SB2 and CS3 in both storage periods. An inverse correlation between Young's modulus and µTBS was observed for the adhesive layer. CONCLUSION: The water storage periods did not alter nanohardness, Young's modulus, and µTBS of adhesives. The adhesive layer of SB2 showed the highest nanohardness and Young's modulus, but the highest dentin bond strength was obtained with SBMP and CSE. Thus, a lower Young's modulus yielded high bond strength. CLINICAL RELEVANCE: The inverse correlation between the Young's modulus of adhesive systems and dentin bond strength suggests adequate resistance of the adhesive to elastic deformation under stress, which are important properties to predict the success of the dental restoration.

Physicochemical properties, metalloproteinases inhibition, and antibiofilm activity of doxycycline-doped dental adhesive.

OBJECTIVES: To evaluate the incorporation of doxycycline (DOX) into a commercial dental adhesive regarding physicochemical properties, microtensile bond strength (µTBS), nanoleakage (NL), nanohardness (NH) and Young's modulus (YM), metalloproteinases (MMP) inhibition, and antibiofilm activity. METHODS: DOX was incorporated into the adhesive at 0.05, 0.1, 0.5, and 1 wt%. Restored teeth were evaluated for µTBS, NL, NH, and YM after 24 -hs and 1-year of water storage. Biofilms of Streptococcus mutans were grown on top of these adhesives and determined for bacterial viability and amount of biomass. The inhibitory effect on MMP was analyzed by in situ zymography under confocal microscopy. RESULTS: Adhesives with 0.5 and 1 wt% of DOX presented reduced pH and degree of conversion. The incorporation of DOX did not affect µTBS and hybrid layer YM. The control group (no DOX) had a decrease in µTBS and the densest silver nitrate areas after 1-year storage. Hybrid layer NH values increased with 0.1 wt% DOX compared to control and 1 wt% DOX groups, at 24 -hs. After 1-year storage, NH of 1 wt% DOX adhesive decreased compared to the control group. The 0.5 and 1 wt% concentrations of DOX decreased the bacterial viability and the biofilm biomass. Confocal images suggest an increased MMP inhibition proportional to the percentage of DOX. CONCLUSION: At any concentration, DOX-doped dental adhesives were able to inhibit MMP activity, diminish nanoleakage, and maintain the resin-dentin bond-strength after 1 year of artificial aging. CLINICAL SIGNIFICANCE: Doxycycline-doped dental adhesive inhibited metalloproteinases activity and preserved interface bond strength. This formulation has a potential to improve adhesive restorations clinical longevity.

Implantes de zircônia na odontologia: revisão de literatura / Zirconia dental implants - a review

Diante da crescente expectativa quanto à estética em Odontologia e da necessidade de tratamentos metal free para casos específicos em regiões estéticas, o uso de implantes cerâmicos tem se tornado objeto de estudo e investimentos desde a década de 70, tornando-se hoje uma possível alternativa aos implantes de titânio. Assim, o objetivo deste estudo foi sistematizar o conhecimento disponível a respeito de implantes dentários de zircônia, avaliando sua viabilidade na implantodontia e a capacidade deste material em responder às exigências mecânicas e biológicas. Uma busca eletrônica foi realizada por meio do banco de dados PubMed utilizando a combinação das seguintes palavras- -chave: "zirconia", "dental implant", "zirconia implant" e "zirconia dental implant", sem restrição de idioma ou data de publicação. Esta pesquisa resultou em 801 trabalhos de potencial interesse. A seleção de artigos para inclusão no estudo com restrição de acordo com o objetivo proposto levou a seleção de 85 artigos relevantes para a revisão de literatura deste trabalho. De acordo com essa revisão, os resultados das pesquisas a respeito do uso da zircônia como matéria base na fabricação de implantes são promissores, embora a documentação científica disponível seja limitada pelas poucas e curtas experiências clínicas, principalmente em termos de longevidade. Estudos biológicos, mecânicos e clínicos publicados até a data parecem indicar que a zircônia pode ser uma excelente opção para os implantes de titânio, principalmente pelas suas propriedades mecânicas, aparência estética e menor adesão bacteriana.

Due to increasing demand for higher aesthetic in dentistry followed by the necessity of metal free rehabilitation for specific cases in esthetic regions, the use of ceramic implants has been object of study since the 70's, becoming today a possible alternative to titanium implants. The aim of this study was to systematize the knowledge available of zirconia implants, evaluating their viability and the ability of this material to respond to the mechanical and biological requirements. An electronic search was performed using the PubMed database and the combination of the following keywords: "zirconia", "dental implant", "zirconia implant" and "zirconia dental implant", without restriction of language or publication date. Eighty five articles were considered relevant to this study and the selection was fulfilled according to the proposed objective. According to this review, the results of research on the use of zirconia as the base material in implant manufacturing are promising, although available scientific documentation is limited by the few short clinical experiences, especially in terms of longevity. Biological, mechanical, and clinical studies published to date suggest that zirconia may be an excellent choice for titanium implants, mainly because of their mechanical properties, aesthetic appearance and lower bacterial adhesion.