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BackgroundA carbon dioxide (CO2) laser has been used to morphologically and chemically modify the dental enamel surface as well as to make it more resistant to demineralization. Despite a variety of experiments demonstrating the inhibitory effect of a CO2 laser in reduce enamel demineralization, little is known about the effect of surface irradiated on bacterial growth. Thus, this in vitro study was preformed to evaluate the biofilm formation on enamel previously irradiated with a CO2 laser (λ = 10.6 µM).MethodsFor this in vitro study, 96 specimens of bovine enamel were employed, which were divided into two groups (n = 48): 1) Control-non-irradiated surface and 2) Irradiated enamel surface. Biofilms were grown on the enamel specimens by one, three and five days under intermittent cariogenic condition in the irradiated and non-irradiated surface. In each assessment time, the biofilm were evaluated by dry weigh, counting the number of viable colonies and, in fifth day, were evaluated by polysaccharides analysis, quantitative real time Polymerase Chain Reaction (PCR) as well as by contact angle. In addition, the morphology of biofilms was characterized by fluorescence microscopy and field emission scanning electron microscopy (FESEM). Initially, the assumptions of equal variances and normal distribution of errors were conferred and the results are analyzed statistically by t-test and Mann Whitney test.ResultsThe mean of log CFU/mL obtained for the one-day biofilm evaluation showed that there is statistical difference between the experimental groups. When biofilms were exposed to the CO2 laser, CFU/mL and CFU/dry weight in three day was reduced significantly compared with control group. The difference in the genes expression (Glucosyltransferases (gtfB) and Glucan-binding protein (gbpB)) and polysaccharides was not statically significant. Contact angle was increased relative to control when the surface was irradiated with the CO2 laser. Similar morphology was also visible with both treatments; however, the irradiated group revealed evidence of melting and fusion in the specimens.ConclusionIn conclusion, CO2 laser irradiation modifies the energy surface and disrupts the initial biofilm formation.

The quality of the dentin root is the most important factor for restoration resin sealing and drives the outcome of endodontic treatment. Objective This study evaluated the effect of different filling pastes and cleaning agents on the root dentin of primary teeth using Fourier-transformed Raman spectroscopy (FT-Raman), micro energy-dispersive X-ray fluorescence (µ-EDXRF) and scanning electron microscopic (SEM) analysis.Material and Methods Eighty roots of primary teeth were endodontically prepared and distributed into 4 groups and filled according to the following filling pastes: Control-no filling (CP), Calen®+zinc oxide (CZ), Calcipex II® (CII), Vitapex® (V). After seven days, filling paste groups were distributed to 4 subgroups according to cleaning agents (n=5): Control-no cleaning (C), Ethanol (E), Tergenform® (T), 35% Phosphoric acid (PA). Then, the roots were sectioned and the dentin root sections were internally evaluated by FT-Raman, µ-EDXRF and SEM. Data was submitted to two-way ANOVA and Tukey tests (α=0.05).Results Regarding filling pastes, there was no significant difference in organic content. CP provided the lowest calcium values and, calcium/phosphoric ratio (Ca/P), and the highest phosphoric values. For cleaning agents there was no difference in organic content when compared to the C; however, T showed significantly higher calcium and Ca/P than PA. All groups showed similar results for phosphorus. The dentin smear layer was present after use of the cleaning agents, except PA.Conclusion The filling pastes changed the inorganic content, however they did not change the organic content. Cleaning agents did not alter the inorganic and organic content. PA cleaned and opened dentin tubules.

Background. CO2 laser has been used to morphologically and chemically modify the dental enamel surface as well as to turn it more resistant to demineralization. Despite a variety of experiments demonstrating the inhibitory effect of CO2 laser in reduce enamel demineralization, little is known about the effect of surface irradiated on bacterial growth. Thus, this in vitro study was preformed to evaluate the biofilm formation on enamel previously irradiated with a CO2 laser (λ = 10.6 µM). Methods. For this in vitro study, it was employed 96 specimens of bovine enamel, which were divided into 2 groups (n = 48): 1) Control-non-irradiated surface and 2) Irradiated enamel surface. Biofilms were grown on the enamel specimens by 1, 3 and 5 days under intermittent cariogenic condition in the irradiated and non irradiated surface. In each assessment time, the biofilm were evaluated by dry weigh, counting the number of viable colonies and in fifth day, were evaluated by polysaccharides analysis, quantitative real time PCR as well as by contact angle. In addition, the morphology of biofilms was characterized by fluorescence microscopy and field emission scanning electron microscopy (FESEM). Initially, the assumptions of equal variances and normal distribution of errors were conferred and the results are analyzed statistically by t-test and Mann Whitney test. Results. The mean of log CFU/ml obtained for the 1-day biofilm evaluation showed that there is statistical difference between the experimental groups. When biofilms were exposed to CO2 laser, CFU/mL and CFU/ Dry Weight in 3 day was reduced significantly compared with control group. The difference in the genes expression (gtfB and gbpB) and polysaccharides was not statically significant. Contact angle was increased relative to control when the surface was irradiated with CO2 laser. Similar morphology was also visible with both treatments, however irradiated group revealed evidence of melting and fusion in the specimens. Conclusion. In conclusion CO2 laser irradiation modify the energy surface and disrupt the initial biofilm formation.

Variable clinical and radiographic alterations were observed, probably due to the large variety of phenotypic characteristics. No specific dental alteration could be related with frontonasal dysplasia.

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