Aim:The aim of this study was to evaluate the surface/mineral changes on enamel before and after the application of acidulated phosphate fluoride (APF) gel, fluoride enhanced hydroxyapatite gel and propolis in conjunction with carbon-dioxide (CO2) laser.Materials and Methods:Crowns of 40 human maxillary central incisors were collected and were divided into four groups of 10 each: Topical fluoride application only, topical fluoride application followed by CO2 laser irradiation, CO2 laser irradiation followed by topical fluoride application and CO2 laser irradiation before and after topical fluoride application. The 10 crowns in each group was again sectioned into four equal parts of mesio-incisal, disto-incisal, mesio-cervical and disto-cervical sections rendering 40 samples in each group. Each group was again subdivided into four subgroups: Subgroup C - untreated enamel surface (control). Subgroup A - APF gel application, subgroup R - fluoride enhanced hydroxyapatite gel application and subgroup P - propolis application. The surface morphology of the test samples were analyzed by scanning electron microscopy and mineral changes by energy dispersion X-ray spectrophotometer.Results:Total mineral content is maximum in Group 4A (CO2 laser irradiation before and after APF gel application) and calcium/phosphate ratio is highest in Group 4R (CO2 laser irradiation before and after Remin-Pro application). Group 2A (APF gel application followed by CO2 laser irradiation) has the maximum fluoride retention.Conclusion:Laser irradiation of enamel through a topically applied APF gel is effective in the prophylaxis and management of dental caries.

No abstract

Aims:The aim of this in vitro study was to evaluate comparatively the effects of multiple autoclaving on surface topography and cyclic fatigue of three different rotary nickel-titanium (Ni-Ti) instruments.Materials and Methods:Twenty-one files each of Twisted Files (TF), Revo-S, and RaCe were used in this study. They were grouped as group 1-TF, group 2-Revo-S, and group 3-RaCe. All the files were autoclaved and subjected for scanning electron microscopic analysis and cyclic fatigue analysis.Results:Data were subjected to statistical analysis using one way analysis of variance (ANOVA) and post hoc Tukey's Kramer multiple comparison test. TF exhibited the highest cyclic fatigue resistance followed by Revo-S and RaCe. Scanning electron photomicrographs showed no obvious surface changes in the files after three autoclaving cycles.Conclusions:Within the limitation of this study, it can be concluded that Twisted Files was the most fatigue resistant compared to Revo-S and RaCe, and multiple autoclaving cycles did not have any significant alterations in the cyclic fatigue resistance of rotary Ni-Ti files.