Effect of Erbium:yttrium aluminum garnet laser on bond strength of a total-etch adhesive system to caries-affected dentin on gingival wall.

PURPOSE: To assess the effect of the erbium:yttrium aluminum garnet (Er:YAG) laser on bond strength of a total-etch adhesive system to the caries-affected dentin on the gingival wall. MATERIALS AND METHODS: Ten human molars with proximal carious lesions were randomly divided into two groups. In the first group, the carious dentin was removed with a bur, whereas in the second group it was removed with the Er:YAG laser. Carious lesions were excavated with one of these two techniques until laser fluorescence values decreased to 15 in the center of the lesions. The teeth were then restored with a total-etch adhesive system (Adper Single Bond 2) and composite resin (Filtek Z250). Five teeth from each group were sectioned to obtain 1 mm2 stick-shaped microtensile specimens from each tooth. Twenty-five specimens were obtained for each group with using this technique. The data were analyzed in independent-samples t-test (α = 0.05). For each removal technique, one sample was analyzed using scanning electron microscopy. RESULTS: No statistically significant differences were found between the bond strength of the Er:YAG laser and the bur-treated groups (P > 0.05). CONCLUSION: The Er:YAG laser treatment did not negatively affect the bonding performance of the total-etch adhesive system to caries-affected dentin on the gingival wall.

Effects of hemostatic agents on shear bond strength of orthodontic brackets.

OBJECTIVES: The aim of this study was to determine the effects of blood contamination and hemostatic agents on shear bond strength (SBS) of brackets and bond failure. MATERIALS AND METHODS: The study material consisted of 57 freshly extracted human premolar and randomly divided into four groups: Group I, control group (n0 = 14); Group II, contamination with blood (n = 13); Group III, contamination with epinephrine ( n = 14); and Group IV, contamination with Ankaferd blood stopper (ABS) ( n = 16). After the bracket bonding procedure, all bonded teeth thermal cycled in deionized water at 5 ± 2°C to 55 ± 2°C for 500 cycles. SBS was applied using a universal test machine. RESULTS: According to Kruskal-Wallis test significant differences were found among the groups P < 0.05. Furthermore, significant differences were recorded between groups with Mann-Whitney U statistical test with Bonferroni correction (P = 0.0083). CONCLUSIONS: Examples contaminated with blood showed a statistically significant lower in vitro SBS than those contaminated with epinephrine, ABS, and control groups. CLINICAL SIGNIFICANCE: In impacted tooth surgical operations, blood contamination poses a substantial risk of bond failure in bonding attachments applications to the impacted teeth. Epinephrine and ABS may be used on surgical exposed impacted teeth operation for the prevention of blood contamination.

Bonding performance of two newly developed self-adhering materials between zirconium and dentin.

PURPOSE: This study evaluated the effect of four resin materials on the shear bond strength (SBS) of a ceramic core material to dentin. MATERIALS AND METHODS: Sixty molar teeth were embedded in a self-curing acrylic resin. All specimens were randomly divided into four groups of teeth, each according to the resin cement used. Sixty cylinders were then luted with one of the four resin materials to dentin (GC EQUIA, Panavia F, Variolink II and Vertise). Then, specimens were stored in distilled water at 37 o C for one day. Shear bond strength of each specimen was measured using a universal testing machine at a crosshead speed of 0.5 mm/minute. The bond strength values were calculated in N, and the results were statistically analyzed using a Kruskal-Wallis and Bonferroni corrected Mann-Whitney U tests. RESULTS: The shear bond strength varied significantly depending on the resin materials used ( P < 0.05). The specimens luted with GC EQUIA showed the highest shear bond strength (25.19 ± 6.12), whereas, the specimens luted with Vertise flow (8.1 ± 2.75) and Panavia F (11.17 ± 3.89) showed the lowest. CONCLUSION: GC EQUIA material showed a higher shear bond strength value than other resin materials.

Effect of caries removal techniques on the bond strength of adhesives to caries-affected primary dentin in vitro.

AIM: The aim of this in vitro study is to evaluate the effects of three different caries removal techniques on the microtensile bond strength of adhesive materials to caries-affected dentin. MATERIALS AND METHODS: Thirty primary molar teeth were used. The teeth were randomly divided into three groups according to the caries removal technique employed: conventional steel bur (group 1); Er:YAG laser (group 2); chemomechanical method (group 3). Each group was divided into two subgroups according to bonding agents: one-step self-etch adhesive and etch-and-rinse adhesive. The teeth were restored with composite resin. Vertical sticks were obtained and subjected to tensile stress. Data were analyzed by two-way analysis of variance (ANOVA), Tukey's test and an independent samples t-test. RESULTS: The values for the laser groups were significantly lower than those of the bur groups for both bonding agents (p<0.05). There were no significant differences between the bur and chemomechanical groups (p > 0.05). CONCLUSION: Bur and chemomechanical techniques in primary teeth were found more successful. Similar results were found according to the adhesives used for each caries removal techniques.

Evaluation of micro-tensile bond strength of caries-affected human dentine after three different caries removal techniques.

OBJECTIVE: This study evaluated the effect that different techniques for removing dental caries had on the strength of the microtensile bond to caries-affected human dentine created by three bonding agents. MATERIALS AND METHODS: Forty-five human molar teeth containing carious lesions were randomly divided into three groups according to the technique that would be used to remove the caries: a conventional bur, an Er:YAG laser or a chemo-mechanical Carisolv(®) gel (n=15). Next, each of the three removal-technique groups was divided into three subgroups according to the bonding agents that would be used: Clearfil(®) SE Bond, G-Bond(®), or Adper(®) Single Bond 2 (n=5). Three 1mm(2) stick-shaped microtensile specimens from each tooth were prepared with a slow-speed diamond saw sectioning machine fitted with a diamond-rim blade (n=15 specimens). For each removal technique one dentine sample was analysed using scanning electron microscopy. RESULTS: There were statistically significant differences in the resulting tensile strength of the bond among the techniques used to remove the caries and there were also statistically significant differences in the strength of the bond among the adhesive systems used. The etch-and-rinse adhesive system was the most affected by the technique used to remove the caries; of the three techniques tested, the chemo-mechanical removal technique worked best with the two-step self etch adhesive system. CONCLUSION: The bond strength values of the etch-and-rinse adhesive system were affected by the caries removal techniques used in the present study. However, in the one- and two-step self etch adhesive systems, bond strength values were not affected by the caries removal techniques applied. While a chemo-mechanical caries removal technique, similar to Carisolv(®), may be suggested with self etch adhesive systems, in caries removal techniques with laser, etch-and-rinse systems might be preferred. CLINICAL SIGNIFICANCE: Caries removal methods may lead to differences in the characteristics of dentine surface. Dentine ultra structure generally affects the bonding of adhesive materials commonly used in restorative dentistry. Whereas etch-and-rinse system, like the ones used in the present study, are affected by these changes, the self etch systems are not affected. Hence, clinicians may opt for caries removal methods and systems appropriate for each patient and practice.