An Evaluation of Er:YAG Laser in an Intact Enamel Treatment on Bonding to the Resin Cement Compared to Four Traditional Techniques.

AIM OF STUDY: Evaluation of the bond strength of the resin cement after enamel conditioning with erbium-doped yttrium aluminum garnet laser compared to other four different techniques. MATERIALS AND METHODS: The study consisted of 50 enamel specimens excluded from the smooth surfaces of newly extracted human 3rd molars. The specimens were randomly divided into five groups in terms of the enamel treatment technique. Each group (n = 10) was conditioned differently by bevel and acid etching group (I), acid etching technique group (II), double acid etching technique group (III), air abrasion followed by acid etching group (IV), and Er:YAG laser followed by acid etching group (V). After enamel treatment, a resin cylinder was installed using split Teflon matrix on each enamel specimen. Then the specimens were exposed to a shear strength device, and shear force was applied. The results were recorded with Newton. The required data were collected and statistically analyzed. A one-way ANOVA test was conducted to compare the five study groups using SPSS version 21 (p < 0.05). RESULTS: All groups showed high shear bond strength values ranging from 19.26 MPa (for group III) to 27.05 MPa (for group V). The enamel treatment with Er:YAG laser followed by acid etching gave the best results with significant differences compared to the other groups. CONCLUSION: Within the limitations of the present study, it can be concluded that the combination between the Er:YAG laser and the acid etching enhances the bond strength of resin cement with the enamel. CLINICAL SIGNIFICANCE: The use of Er:YAG laser followed by acid etching can be a successful technique for enamel conditioning and the results showed their superiority over the other groups.

Effect of CPP-ACP on efficacy and postoperative sensitivity associated with at-home vital tooth bleaching using 20% carbamide peroxide.

OBJECTIVES: To evaluate CPP-ACP effect on colour change and tooth sensitivity (TS) associated with at-home vital tooth bleaching using 20% carbamide peroxide (CP). METHODS: A randomised double-blind placebo-controlled clinical trial was conducted to measure the TS and tooth colour change of 24 patients at 3-day, 7-day, 14-day and 30-day periods. The participants were instructed to apply 20% CP (7 days-04 h each) followed by the application of either CPP-ACP or non-active placebo paste, delivered by the bleaching custom tray (7 days-30 min each). Lightness (L*), redness (a*) and yellowness (b*) were measured using a digital spectrophotometer and the overall colour changes ∆E were calculated. ∆E and TS values were statistically analysed. The level of statistical significance was established at p = 0.05. RESULTS: No significant differences were detected between CPP-ACP and placebo groups regarding the ∆E. The ∆E measurements presented significant differences within CPP-ACP groups between 3-day vs. 14-day and 30-day measurements. The CPP-ACP application reduced significantly the TS reported by the participants at 3-day when compared with the placebo group. CONCLUSION: The application of CPP-ACP paste during at-home tooth bleaching with 20% CP was beneficial since its use reduced the TS and presented no deteriorating effect on the colour change. CLINICAL RELEVANCE: The current findings are of importance for clinicians to manage TS reported by patients when a high CP bleaching agent is used.

An Evaluation of GuttaFlow2 in Filling Artificial Internal Resorption Cavities: An in vitro Study.

INTRODUCTION: Obturation of root canal with internal resorption represents a major challenge in Endodontics. In spite of that, usual obturation techniques are often employed without considering the best technique to solve this problem. The goal of this study was to investigate the ability of GuttaFlow2 in filling artificial internal resorption cavities. MATERIALS AND METHODS: The study sample included 36 human upper central incisors that were prepared using Protaper system (F4). Internal resorption cavities were prepared by cutting each tooth at 7 mm from the apex and preparing hemispherical cavities on both the sides and then re-attaching them. The sample was randomly separated into three groups (n = 12 in each group). In the first group, thermal injection technique (Obtura II) was employed and served as the control group. In the second group, injection of cold free-flow obturation technique with a master cone (GF2-C) was employed, whereas in the third group injection of cold free-flow obturation without a master cone (GF2) was followed. The teeth were re-cut at the same level as before and examined under a stereomicroscope. Subsequently, the captured images were transferred to AutoCAD program to measure the percentage of total filling "TF," gutta-percha "G," sealer "S," and voids "V" out of the total surface of the cross sections. RESULTS: All materials showed high filling properties in terms of "total filling," ranging from 99.17% (for Obtura II) to 99.72% (for GF2-C). Regarding gutta-percha percentages of filling, they ranged from 83.15 to 83.93%, whereas those for the sealer ranged from 5.71 to 15.24%. GuttaFlow2 group with a master cone appeared to give the best results despite the insignificant differences among the three groups. CONCLUSION: The GuttaFlow2 with a master cone technique seemed to be a promising filling material and gave results similar to those observed with Obtura II. It is recommended for use to obturate internal resorption cavities in clinical practice due to its good adaptability to root canal walls, ease of handling, and application. CLINICAL SIGNIFICANCE: Internal resorption defects can be successfully filled with GuttaFlow2 material when supplemented with a master cone, and the results are comparable with those obtained with the Obtura II technique.