Formation of protective deposits by anti-erosive toothpastes-A microscopic study on enamel with artificial defects.

This study investigated formation of protective deposits on the enamel surface after application of several anti-erosive toothpastes with different active ingredients. NaF-containing Sensodyne Pronamel, SnCl2 /F-based Elmex Erosion Protection and calcium phosphate-based BioRepair Plus Sensitivity Control, SensiShield and Enamel Care toothpastes with claimed anti-erosive properties were tested. Artificial saliva and Elmex Erosion Protection mouth rinse served as control groups. The toothpastes were applied 30 times by a toothbrush for 2 min per day, mouth rinse for 30 s on polished enamel of thirty five human molars (n = 5) with series of five rhomboid-shaped indents of various length prepared by a Knoop indentor. After 15 and 30 applications, the shape of the indents and surface morphology was characterised using light and scanning electron microscopy. At the end of treatment, the samples were exposed to 0.2 wt. % citric acid (pH 3.30) to test resistance of the treated enamel to erosion. Pronounced differences were observed between protective properties of the toothpastes. While Sensodyne Pronamel and BioRepair Plus Sensitivity Control did not produce any protective deposits, Enamel Care formed a compact layer of deposits which protected the enamel surface against erosion. With Elmex Erosion Protection and SensiShield fractured indent edges and scratches on the treated enamel suggested that their abrasive properties prevailed over ability of active ingredients to form deposits. These results revealed that toothpastes with strong potential to form acid-resistant deposits on the enamel surface and of low abrasivity should be used for effective prevention of enamel erosion. SCANNING 38:380-388, 2016. © 2015 Wiley Periodicals, Inc.

Comparison of bonding performance of self-etching and etch-and-rinse adhesives on human dentin using reliability analysis.

PURPOSE: To estimate the in vitro reliability of typical self-etching and etch-and-rinse adhesives of various application protocols. MATERIALS AND METHODS: The following adhesives were applied on flat dentin surfaces of extracted human teeth (n = 223): self-etching two-step adhesives: AdheSE (AH), Clearfil SE Bond (CL), OptiBond SE (OS); one-step adhesives: Adper Prompt L-Pop (ADP), Adper Prompt (AD), and Xeno III (XE); all-in-one adhesive: iBond (IB); etch-and-rinse three-step adhesives: OptiBond FL (OF), two-step Gluma Comfort Bond (G), Excite (E) and Prime & Bond NT (PB). Composite buildups were prepared using a microhybrid composite, Opticor New. Shear bond strength was determined after 24 h of storage at 37 degrees C in distilled water. The results were analyzed with a nested ANOVA (adhesive, type of adhesive) followed by the Fisher post-hoc tests of group homogeneity at alpha = 0.05. A two-parameter Weibull distribution was used to calculate the critical shear bond strength corresponding to 5% probability of failure as a measure of system reliability. RESULTS: ANOVA revealed a significant decrease (p < 0.001) in the mean shear bond strength as follows: AH=CL=OS=G=E=OF>AD=IB=XE>PB=ADP, but no significant difference (p > 0.48) between the etch-and-rinse and self-etching adhesives. The corresponding characteristic bond strength of Weibull distribution ranged between 24.1 and 12.1 MPa, Weibull modulus between 8.3 and 2.1, and the critical shear bond strength varied from 16.0 to 3.0 MPa. CONCLUSION: Pronounced differences in the critical shear bond strength suggest reliability variations in the adhesive systems tested, which originate from chemical composition rather than type of adhesive.

Diode laser-activated bleaching.

This study describes a preclinical investigation with laser-activated bleaching agent for discolored teeth. Bleaching techniques involve a broad-spectrum approach utilizing hydrogen peroxide (3-38%) with or without heat or laser, carbamide peroxide (10-30%), or a mixture of sodium perborate and hydrogen peroxide. Extracted human maxillary central incisors were selected. In the bleaching experiment, 38% hydrogen peroxide was used. Two different laser systems and light emission diodes for activation of the bleaching agent were used: diode laser, wavelength 970 nm, and infra-red diode laser, wavelength 790 nm, with eight blue light emission diodes, wavelength 467 nm. The enamel surface was evaluated with the scanning electron microscope. The method of chemical oxidation resulted in a 2-3 shade change in one treatment (15 min). Shorter time (5 min) was not effective. The diode laser, wavelength 970 nm, and the bleaching agent produced the same effect but with a shorter time of bleaching process (5 min - 1 W, 2.5 min - 2 W). Infra-red diode laser, wavelength 790 nm with eight blue light emission diodes, wavelength 467 nm, and the bleaching agent reached the desired color shade also after a shorter time (5 min - 40 mW). Slight surface modification after the bleaching process was detected with scanning electron microscopy. Currently, the laser has been proven the most valuable energy source for power bleaching with simple and short application in the dental office.

Endodontic treatment with application of Er:YAG laser waveguide radiation disinfection.

OBJECTIVE: The objective of this study is to examine the ability of Er:YAG laser radiation. Using a movable waveguide helps to obtain an antibacterial effect, not only in root canal walls but also in the surrounding tissues. BACKGROUND DATA: Conventional endodontic treatment is not fully effective due to microbial colonization of root canal walls dentin in premolars and molars. Various laser systems seem to be effective to kill the remaining microbial content in the root canal. The problem is in the flexibility of laser system tips. MATERIALS AND METHODS: The Er:YAG laser system was designed with a fluorocarbon polymer-coated silver hollow glass waveguide. Root canal systems of 44 premolars and molars were treated endodontically, using a step-back technique; 10 teeth were then treated with calcium hydroxide paste, and 22 teeth were irradiated by a movable waveguide. Before and after treatment, the colony-forming units were counted to determine 21 various microorganisms. RESULTS: Classical enlargement and shaping of the root canal is effective in 60%. Application of calcium hydroxide prepares sterile root canal in 80%. Er:YAG laser irradiation via movable waveguide (energy of 100 mJ, 30 pulses, repetition rate 4 Hz) can ensure residual disinfection of the root canal. CONCLUSION: Application of Er:YAG laser radiation through a flexible waveguide helps to attain antibacterial effect, not only in the root canal walls, but also in the surrounding tissues. Therapeutic doses of laser radiation guarantee one-step disinfection, including of anaerobic microorganisms.