Luiz Thadeu de Abreu Poletto

Light Transmission through a Translucent Fiber Post

This study is a quantitative assessment of the luminous energy transmitted through different translucent fiber posts. After embedding the posts in black resin, the blocks were submitted to sequential cuts in a precision machine, and depths of 16 mm, 12 mm, 8 mm, and 4 mm were assessed for light transmission with a digital photometer. The quantitative analysis showed significant differences between different posts and depths. Furthermore, the values obtained revealed that the quantity of luminous energy transmitted depends on the type of post and that for all of them there was a significant reduction of the quantity of light transmitted as the depth increased. Even without the post, the luminous intensity inside the canal seems to decrease to levels that are insufficient for polymerization, especially in the apical third.

Antimicrobial effect of photodynamic therapy in carious lesions in vivo, using culture and real-time PCR methods

BACKGROUND The aim of this study was to evaluate the antimicrobial effect of photodynamic therapy (PDT) in carious lesions in vivo by culture and real-time PCR methods. METHODS Ten teeth with deep active carious lesions were selected and five portions of carious dentin were removed for each tooth. Two increments were used as control, to represent the superficial and deep dentin, respectively. Methylene blue at 100mg/L was placed in contact with the cavity for 5min, before being irradiated with a halogen light source for 1min. Then, after PDT, other three portions were removed. The samples were processed in laboratory and the number of viable cfu was obtained. The real-time PCR analyses were performed in two increments of carious dentin, removed before and after PDT. The Streptococcus mutans DNA was isolated from carious dentin samples and amplification and detection of DNA were performed with real-time PCR. The cavities were then restored with glass-ionomer cement. RESULTS Using conventional culture methods, the results demonstrated that viable bacteria were significantly reduced in all of the agar plates following photosensitization. No difference was found between both groups regarding S. mutans DNA quantification by real-time PCR. CONCLUSION Although PDT may not affect the number of S. mutans DNA copies immediately after the treatment, clear reduction of the number of cfu was found. Despite its promising use for eliminating bacteria in dental caries treatment, further studies are necessary to establish an effective clinical protocol for the PDT.

Ultrastructural evaluation of the hybrid layer after cementation of fiber posts using adhesive systems with different curing modes

This in vitro study evaluated the adhesive interface of intraradicular fiber glass posts and root dentin using scanning electron microscopy (SEM). Forty-eight single-rooted premolars were randomly divided into 6 groups consisting of chemical, dual, or light cured adhesive systems combined with either chemical or dual cure resin cements. Scanning electron microscopic analysis showed the best results for continuity, density and morphology of the hybrid layer and resin tags for the combination of a self-cure adhesive with self-cure cement resin, followed by a dual-cure adhesive with self-cure cement resin, and finally a light-cure adhesive with self-cure cement. For the dual-cure resin cement, the same relation may be observed. The apical third was the most critical region for evaluated the criteria for all combinations of materials (Kruskal-Wallis and Friedman tests; p<0.001). Generally, the simplification of steps in the adhesive system and the polymerization reaction of resin adhesives and cements produced a direct effect on the quality of the adhesive post/dentin substrate interface.

Photodynamic therapy of cariogenic agents: A systematic review

The purpose of this systematic review was to evaluate the current status of the photodynamic therapy (PDT) against cariogenic micro-organisms. Publications with abstracts, published in English and available online in PubMed, were included. To identify relevant publications, all abstracts obtained from the search in PubMed were read independently by the authors. In total, 19 studies were reviewed. It was difficult to compare the results among all the studies because of their heterogeneity regarding photosensitizer, light source, exposure time, and photosensitizer incubation period before the irradiation. All but one in vitro studies assessed showed significant killing of micro-organisms demonstrating the antibacterial effect of PDT against cariogenic bacteria. Due to heterogeneity in the treatment parameters, there are no available clinical protocols to apply the PDT in vivo and further works are now being undertaken to make this treatment clinically accessible and to determine the efficacy of PDT on carious dentin in vivo.The purpose of this systematic review was to evaluate the current status of the photodynamic therapy (PDT) against cariogenic micro-organisms. Publications with abstracts, published in English and available online in PubMed, were included. To identify relevant publications, all abstracts obtained from the search in PubMed were read independently by the authors. In total, 19 studies were reviewed. It was difficult to compare the results among all the studies because of their heterogeneity regarding photosensitizer, light source, exposure time, and photosensitizer incubation period before the irradiation. All but one in vitro studies assessed showed significant killing of micro-organisms demonstrating the antibacterial effect of PDT against cariogenic bacteria. Due to heterogeneity in the treatment parameters, there are no available clinical protocols to apply the PDT in vivo and further works are now being undertaken to make this treatment clinically accessible and to determine the efficacy of PDT on cario...