Effect of aPDT on Streptococcus mutans and Candida albicans present in the dental biofilm: Systematic review.

To evaluate the effect of aPDT on S. mutans and C. albicans present in the dental biofilm, using methylene blue as a photosensitizer in different pre-irradiation times. The searches were made on Pubmed, Web of Science, Bireme, Scopus and Cochrane Library, and were complemented by screening the references of selected articles in the attempt to find any article that did not appear in the database search. The searches were performed by two researchers and limited to studies involving human subjects published in the English language. Inclusion criteria included in vitro studies with aPDT; studies that used methylene blue as a photosensitizer; studies that used low power laser; studies that evaluated S. mutans or C. albicans. Studies published in a non-English language, patents, in vivo or in situ studies; case reports, serial case, reviews and animal studies were not included. Studies published before 1996 were also not included. Initially, the search resulted in 68 published studies. 16 records were excluded because they were duplicated. The analysis of titles and abstracts resulted in the exclusion of 48 of the published studies, resulting in 4 studies included in the systematic review. The aPDT was effective in three of the four papers selected for the systematic review and the pre-irradiation time used was 5 or 15 min. This therapy had satisfactory results in both C. albicans and S. mutans when using methylene blue as a photosensitizer.

Influence of pre-irradiation time employed in antimicrobial photodynamic therapy with diode laser.

The aim of the present study was to evaluate, in vitro, the effect of different pre-irradiation times of the photosensitizer in photodynamic therapy in biofilms formed by Streptococcus mutans and Candida albicans, through the evaluation of the microbial load. The factors under study were as follows: times of pre-irradiation of the photosensitizer in three levels (1, 2, or 5 min). For the control of the cariogenic dental biofilm with antimicrobial photodynamic therapy (aPDT), methylene blue (0.01%) was used in association with the diode laser (InGaAlP) with a wavelength of 660 nm. Chlorhexidine digluconate (0.12% CHX) and saline were used as positive and negative controls, respectively. The study design was carried out in complete and randomized blocks. The sample consisted of 15 S. mutans biofilms cultures, randomly divided into five groups and 15 C. albicans cultures, also divided into five groups. The experiment was performed in triplicate (n = 3) and the response variables were obtained through quantitative analysis of bacterial viability, expressed in colony-forming units (CFU) per square millimeter of the specimen area. The data were analyzed with the aid of the ANOVA one-way test and Tukey's post-test. All analyses were performed using the Graph Pad Prism 4.0 program, with a significance level of 5%. For the S. mutans group, only the saline solution presented a statistically significant difference when compared to the other treatments (p < 0.05), that is, the treatment with aPDT, irrespective of the irradiation time applied, was similar to the treatment with CHX and both were more effective in reducing cariogenic biofilm compared to saline. For the group of C. albicans, there was no statistical difference between the groups (p > 0.05). Therefore, it can be concluded that the treatment with aPDT reduced the number of CFUs of S. mutans in a similar way to CHX, independently of the pre-irradiation time applied. No effect of this therapy or of the different pre-irradiation times on the C. albicans biofilm could be observed. In this way, the pre-irradiation time of 1 min can be used to reduce the microbial load of S. mutans.

Microleakage of Sealants after Phosphoric Acid, Er: YAG Laser and Air Abrasion Enamel Conditioning: Systematic Review and Meta-Analysis.

PURPOSE: The aim of this systematic review and meta-analysis is to answer the focused question: Does the application of phosphoric acid, Er:YAG laser and air abrasion enamel conditioning methods previous to the oclusal sealant application in human permanent molars influence the microleakage? STUDY DESIGN: A literature research was carried out in the Pubmed Medline, Web of Science, Scopus and Cochrane databases using with the MeSH terms and keyword search strategy. A supplemental hand search of the references of retrieved articles was also performed. Inclusion criteria comprised ex vivo studies (extracted teeth) with permanent human teeth that used chemical (phosphoric acid) or mechanical (Er:YAG laser and air abrasion) conditioning methods previous the sealant application. The studies should evaluate microleakage as an outcome. Meta-analysis pooled plot were obtained comparing the microleakage after pre-treatment with phosphoric acid, Er:YAG and air abrasion enamel conditioning for sealant application using RevMan software. RESULTS: The search resulted in 164 articles, 55 records were excluded because they were duplicated. The analysis of titles and abstracts resulted in the exclusion of 105 studies. Four studies were included in the systematic review and the meta-analysis. According to the risk of bias evaluation, the four studies were considered low risk of bias. The meta-analysis showed that phosphoric acid had lower microleakage than Er:YAG laser (p < 0.001) and air abrasion (p < 0.001), with heterogeinity of I2 = 0% and I2 = 71%, respectively. It was not found statistical difference when compared phosphoric acid and phosphoric acid combined with Er:YAG laser and air abrasion (p > 0.05). CONCLUSION: The evidence supports that the pretreatment with phosphoric acid leads lower microleakage in oclusal sealants than Er:YAG laser and air abrasion.

Validation of pH cycling model to induce artificial carious lesions in bovine dentin

Introduction and objective:The purpose of the study was to evaluate different pH cycling protocols on the induction of artificial carious lesions in bovine dentin, since the most appropriate protocol to be applied is still not fully established. Material and methods: Fragments of bovine dentin (4 x 4 x 2 mm) were embedded in resin, polished and 7 mm² of each fragment was isolated with wax. The specimens were divided into three groups (A, B, C) according to the time of immersion in the demineralizing solution (1.5 ml). Group A - 15 minutes; Group B - 30 minutes; Group C - 60 minutes and subsequently immersed for 22 hours in a remineralizing solution (1.5 ml). Microhardness measurements were conducted initially, daily and after each pH cycling for 4 days. The Split-plot design (ANOVA) was applied. Results: There was a significant interaction between time and cariogenic challenge (p<0.0001). Bonferroni comparisons were executed to identify the differences over the cariogenic challenge, showing that increasing the immersion time in demineralizing solution for each pH cycling assessed, the cariogenic challenge aggressiveness increased (A

Gubernacular cord and canal: does these anatomical structures play a role in dental eruption?

Introduction: The gubernacular cord is an original structure of the dental lamina, which undergoes apoptosis and their remnants were organized in the form of epithelial islets and strands that lined up, leaving the reduced epithelium of the enamel organ towards the oral mucosa. This structure is located within the gubernacular canal, which can be identified as a small opening in the alveolar region of the lingual or palatal surface of the deciduous teeth. Objective: To conceptualize, identify and assess the possible contribution of the gubernacular cord and canal in the process of tooth eruption. Literature review: A review of literature on Pubmed, Medline and Bireme databases, without datum restriction. Little amount of scientific articles were found, and only 14 studies were identified. The authors addressed the matter succinctly, with little information about these structures, which can play an important role in the process of tooth eruption. Conclusion: The gubernacular cord and canal are anatomical structures located in the alveolar bone crest of the maxilla or mandible, behind the deciduous teeth. These structures appear to exhibit the ability to aid the eruption path of the permanent teeth successors. Despite being a relevant subject, few professionals know this structure and its possible role in the process of tooth eruption.