The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

Caries activity tests are being used to assess caries risk in children. In recent years the purpose of most studies has been to develop practical, quick, reliable and economic tests. Clinical studies showed that the difference in sensitivity to the bitter taste of 6-n-propylthiouracil (PROP) is a heritable trait and may influence children’s nutritional habits and caries development. The aim of this study was to investigate the relation between PROP sensitivity and caries activity in schoolchildren, in comparison with different caries activity tests. One hundred and twenty children aged between 7 and 12 years (mean age 9.97 ± 1.59) were investigated to determine socioeconomic status and oral hygiene habits, fluoride consumption, DMFT, DMFS, df, dfs, plaque indexes, and nutritional habits. Children were divided into three groups according to their caries risk status based on the Cariogram. The solution test and the PROP-impregnated filter paper test were used together to determine PROP sensitivity. After all associated factors had been controlled, stepwise regression analyses revealed that DMFT and dfs scores were important determinants of PROP. According to dfs, the sensitivity of the Cariogram and of PROP tests was 0.85 and 0.70, respectively, and specificity was 0.32 and 0.33, respectively. There was an inverse significant relationship between PROP sensitivity and DMFT, DMFS, and dfs results (p < 0.01). In conclusion, PROP nontasters were significantly more likely to have high caries risk than PROP tasters (p < 0.01).

UNLABELLED:Conservative techniques for treatment of discolored human enamel include in-office bleaching with heat-activated 35% hydrogen peroxide, Nightguard vital bleaching with 10% carbamide peroxide, and enamel microabrasion with 18% hydrochloric acid.OBJECTIVES:In this study, these bleaching techniques were performed on 30 extracted teeth to evaluate their effects on microhardness of enamel surfaces.METHODS:The enamel surface microhardness measurements were performed 0, 24, 48, and 72 hours and 1 week after treatment. Paired t tests were performed in the statistical analyses.RESULTS:No changes were found on specimens treated with carbamide peroxide. There was a significant decrease in the surface microhardness of enamel after 0 and 24 hours when the specimens were treated with 18% hydrochloric acid (softening 85.7 and rehardening 99.4) or with 35% hydrogen peroxide (softening 85.7). However, after 72 hours, significant rehardening was observed in these groups (P <.001).CONCLUSION:According to the results, except Nightguard vital bleaching, all other techniques softened the enamel surface.

OBJECTIVES:The objective of this study was to assess the effect of a one-bottle bonding agent on sealant success after 3, 6, 12, and 24 months.METHOD AND MATERIALS:The sample group consisted of 30 schoolchildren (8 to 10 years of age) who had all their permanent first molars sound and unsealed. Occlusal sealants were placed on first molars according to a split-mouth design. Sealant scoring occurred at 3, 6, 12, and 24 months and was performed by two clinicians blinded to the treatment group. Fisher's exact test was used to analyze the data.RESULTS:The clinically acceptable marginal integrity rates for sealants with a bonding agent after 3, 6, 12, and 24 months were 93%, 93%, 83%, and 79%, respectively. For sealants without a bonding agent, the clinically acceptable marginal integrity rates after 3, 6, 12, and 24 months were 90%, 88%, 81%, and 77%. The rates for no color change in sealants with a bonding agent after 3, 6, 12, and 24 months were 96%, 93%, 81%, and 75%, respectively. For sealants without a bonding agent, the no color change rates after 3, 6, 12, and 24 months were 93%, 93%, 79%, and 72%. After 24 months, 73% of the sample group were available for recall. The retention rates for sealants with and without a bonding agent after 24 months were 79% and 75%, respectively. The results of the statistical analysis showed that there were no differences among the sealants with and without bonding agents evaluated in relation to marginal integrity, marginal discoloration, and anatomic form.CONCLUSION:The success of a sealant is related to whether the sealant is applied under optimal conditions. The results of this study show that at the 2-year mark, the placement of a bonding agent under sealants did not significantly affect the clinical success of sealants.

OBJECTIVES:The aim of this study was to investigate the effect of pre- and postoperative bleaching with 10% carbamide peroxide on marginal leakage of amalgam and resin composite restorations.METHOD AND MATERIALS:Three groups were made using 30 extracted, caries-free third molars (n = 10). In the preoperative group, bleaching was performed with 10% carbamide peroxide, followed by the placement of resin composite and amalgam restorations on Class V cavity preparations. In the postoperative group, bleaching was performed after the resin composite and amalgam restorations were fabricated. The third group served as a control in which no bleaching was performed. Dye penetration was used for evaluation of marginal leakage.RESULTS:Chi-square test showed that marginal leakage of resin composite restorations increased in both pre- and postoperatively bleached groups, but marginal leakage of amalgam restorations showed no alterations.CONCLUSION:Bleaching with carbamide peroxide may alter the marginal leakage of resin composite restorations, but amalgam restorations are not affected adversely in vitro.

Tendon disorders with a chronic nature, including the rotator cuff, are extremely common, and represent a major clinical problem. Mechanical overload has been proposed as an important etiologic factor in tendinopathies. Nitric oxide (NO), a free radical produced by nitric oxide synthases (NOSs), is a potent regulator and stimulator of biological processes including tendon degeneration and healing. It is also involved in response to mechanical stimuli in different tissues. In an animal model of acutely injured tendon healing temporal and differential expression of NOS isoforms has been demonstrated, suggesting that different patterns of NOSs expression may have different biological functions. Therefore, we hypothesized that tendon overuse may result in a differential upregulation of NOSs, particularly iNOS. An animal model of supraspinatus tendon overuse was utilized, which consisted of treadmill running. A group of animals of the same strain and age subjected to normal cage activity were used as controls. Following a 4-week exercise protocol supraspinatus tendons were harvested, RNA was extracted, and subjected to competitive reverse transcription and polymerase chain reaction (RT-PCR) to determine the expression levels of inducible-, endothelial-, and neuronal-NOS isoforms (i-, e-, and nNOS). The mRNA expression of all three NOS isoforms increased in the supraspinatus tendons as a result of overuse exercise. iNOS and eNOS mRNA expression increased fourfold (p < 0.01), and there was an increase, but statistically not significant, in nNOS mRNA expression in the overused tendons when compared with the controls. This study is the first to show that NOS isoforms are upregulated in rotator cuff tendon as a result of chronic overuse, and suggests the involvement of nitric oxide in the response of tendon tissue to increased mechanical stress.

Several caries activity tests were used to investigate the caries risk of patients with fixed orthodontic appliances. Twenty young individuals, with a mean age of 11 years, participated in this study. Ten subjects were free of any orthodontic appliances and formed the control group. The other 10 individuals had been wearing fixed orthodontic appliances for at least 4 months. Stimulated saliva samples were obtained from all patients. Saliva samples were used to investigate the salivary flow rate, the salivary buffer capacity, and mutans streptococci and lactobacilli counts. The orthodontic patients exhibited a significant increase in salivary flow rate. Results of statistical analyses were nonsignificant in all other tests, suggesting that fixed orthodontic appliances are not the sole factor increasing the patient's caries risk during orthodontic treatment.

This study was performed to determine the fluoride concentration of the various cementum surfaces in different tooth groups to find out the most proper teeth and tooth surfaces for different cementum studies. For this purpose, direct measurements of phosphorus and fluoride were carried out in an acid etch biopsy solution. The findings indicate that incisors with exposed cementum are the most inappropriate teeth in comparison with the other groups. According to the results obtained it may be recommended that the studies related to fluoride uptake for cementum should be performed on teeth with no gingival recession or on the unerupted teeth.

The purpose of this study was to investigate the fluoride releasing pattern of several visible light-curing glass-ionomers and one fluoride-containing filling material, from the viewpoint of curing time. Standardized blocks of Time Line (Caulk-USA), XR-Ionomer (Kerr-USA), Vitrebond (3M-USA) and Heliomolar-Ro (Vivadent-Lichtenstein) were light cured for 20, 40 and 60 s, and then stored in deionized distilled water at 37 degrees C for 24, 48, 72 h and 7 days. The water was changed every day and measurements of the fluoride released from the materials were made daily. The results were compared statistically with the results obtained from Ketac-Bond (Espe-Germany) prepared in the same manner. The levels were highest for the first 24 h; in the following days they decreased rapidly. The fluoride-releasing patterns of all these materials were similar to each other. The fluoride release was the highest from XR-Ionomer, and the lowest from Heliomolar-RO. For Time Line glass-ionomer, the fluoride release from 20 s cured blocks was significantly higher than the fluoride release from 40 and 60 s cured blocks at the end of 1 week. It was observed that the fluoride release from Ketac-Bond was significantly lower than XR-Ionomer and Vitre-Bond and higher than Time Line and Heliomolar-Ro.