In vitro wear resistance of conventional and flowable composites containing various filler types after thermomechanical loading.

OBJECTIVE: To comparatively assess the wear resistance of conventional and flowable composites containing different filler types using thermomechanical chewing simulation. MATERIALS AND METHODS: Six different composite resin materials were used: a conventional and flowable composite from each of three manufacturers respectively classified by different filler characterizations: (1), a nanohybrid conventional (G-aenial Posterior, GC) and flowable (G-aenial Universal Injectable, GC), (2) a nanofilled conventional (Filtek One Bulk-fill Restorative, 3M) and flowable (Filtek Ultimate Flow, 3M), and submicron-filled conventional (Estelite Posterior Quick, Tokuyama) and flowable (Estelite Bulk-Fill Flow, Tokuyama). The buccal surfaces of extracted human premolars were planarly abraded and used as control (n = 12). The prepared surfaces were subjected to wear using a thermocycler chewing simulator against 6-mm diameter steatite balls for 240,000 cycles, simulating 1 year of in vivo use. Digital profiles of treated sample surfaces were scanned using a laser scanner, and the volume loss and maximum depth of loss were calculated. Two-way MANOVA was used to compare the wear volume loss and depth according viscosity (conventional/flowable) and filler type (nanohybrid, nanofilled, submicron-filled), and multiple comparisons were performed using Duncan's test. RESULTS: Wear volume loss and loss depth were significantly lower in enamel than in all composite resin groups. The wear volume loss and loss depth of nanofilled composites were significantly higher than the other composite filler types, with no significant difference in either parameter between the nanohybrid and submicron-filled composite groups. With respect to apparent viscosity, wear volume loss and loss depth of conventional composites were significantly lower than the flowable composites. CONCLUSIONS: The type of composite filler and its apparent viscosity significantly influence the in vitro wear resistance of the material. All composite materials tested demonstrated a susceptibility to simulated wear that was two to three times greater than that of human enamel. CLINICAL SIGNIFICANCE: Flowable composite resins provide a level of convenience in clinical application. Despite advancements in their wear characteristics, they continue to display inferior wear resistance compared to conventional composite resins. Nevertheless, all tested composite resins exhibited a significantly higher potential for wear than human enamel.

The prevalence and predictive factors of dentine hypersensitivity among adults in Turkey.

AIM: This study sought to determine the prevalence of dentine hypersensitivity (DH) among adults in Turkey. Also, to ascertain the association between DH and both etiological predictors and demographic patient characteristics. MATERIAL METHOD: Using a questionnaire and thermal and evaporative tests, 259 women and 209 men in the age range of 18 to 72 were analyzed. Individually, a clinical evaluation of DH signs was conducted. The DMFT index, gingival index, and gingival bleeding were reported for each subject. The gingival recession and tooth wear of sensitive teeth were also evaluated. Pearson Chi-square test was used to compare categorical data. Logistic Regression Analysis was used to examine the risk factors of DH. Data with dependent categorical variables were compared using the McNemar-Browker test. The significance level was p < 0.05. RESULTS: The average age of the population was 35.6 years. In the present study, a total of 12,048 teeth were analyzed. 1755 had thermal hypersensitivity (14.57%), while 470 experienced evaporative hypersensitivity (3.9%). The incisors were the teeth most impacted by DH, whereas the molars were the least affected. Exposure to cold air and sweet foods, gingival recession, and the presence of noncarious cervical lesions were all strongly linked to DH (Logistic regression analysis, p < 0.05). The cold stimulus increases sensitivity more than the evaporation stimulus. CONCLUSION: Significant risk factors for both thermal and evaporative DH include cold air, consumption of sweet food, presence of noncarious cervical lesions, and gingival recession. More epidemiological research in this area is still required to fully characterize the risk factors and implement the most effective preventive interventions.

Clinical performance of high-viscosity glass ionomer and resin composite on minimally invasive occlusal restorations performed without rubber-dam isolation: a two-year randomised split-mouth study.

OBJECTIVE: The aim of this clinical trial was to evaluate the 2-year clinical performances of high-viscosity glass ionomer and nanohybrid resin composite restorations performed without rubber dam isolation. MATERIALS AND METHODS: Occlusal carious lesions on the right and left mandibular second molars of 56 patients (26 female, 30 male patients) were restored in a split-mouth design. High-viscosity glass ionomer (Hv-GIC) (Equia, GC) and nanohybrid resin composite (GrandioSO, Voco) were used as restorative materials. Clinical evaluations of the restorations were performed according to the Fédération Dentaire Internationale criteria. Data were analysed using the Friedman's analysis of variance and Mann-Whitney U tests (α=0.05). RESULTS: After 2 years, the success rate of Hv-GIC restorations was 96% and that of resin composite restorations was 100%. Hv-GIC showed lower marginal discoloration and greater surface wear and loss of anatomic form (p<0.05). Resin composite showed significantly better surface lustre. CONCLUSION: The 2-year performance of resin composite was similar to that of Hv-GIC for the occlusal restorations of mandibular second molars, in spite of being performed without rubber-dam isolation. CLINICAL RELEVANCE: Saliva contamination can be a clinically significant problem for dental restorations. High-viscosity glass ionomers are a satisfactory alternative to resin composites with the advantage of fast application in such situations. TRIAL REGISTRATION: Clinical Trials Registration number-date: NCT04488380-22/07/2020, retrospectively registered.

Three-year clinical evaluation of high-viscosity glass ionomer restorations in non-carious cervical lesions: a randomised controlled split-mouth clinical trial.

OBJECTIVE: To compare the 3-year clinical performance of high-viscosity glass ionomer restorations with that of composite restorations in non-carious cervical lesions (NCCLs). MATERIALS AND METHODS: One hundred thirty-four NCCLs were randomised into two groups according to a split-mouth design. In the experimental group (Hv-GIC), lesions were restored with a high-viscosity glass ionomer (EQUIA Fil, GC), whereas a composite resin (G-aenial, GC) was applied in the control group (E&Ra/comp). All restorative materials were used according to the manufacturers' instructions. Clinical evaluations were performed after 1 week, 6 months, 1 year, 2 years, and 3 years using FDI (World Dental Federation) criteria. Data were analysed using Friedman's ANOVA and Mann-Whitney U tests (α = 0.05). RESULTS: While retention rates of the Hv-GIC group were 98.5%, 96%, 91%, and 87% in respective evaluation periods, no retention loss was observed in the E&Ra/comp group at any time. There was a statistically significant difference between study groups regarding the retention criterion in both the second and third years (p = 0.008 and p = 0.003, respectively). Furthermore, there was a statistically significant difference between the groups in terms of surface lustre at the third-year recall, in favour of the E&Ra/comp group (p = 0.022). CONCLUSIONS: The 3-year clinical performance of E&Ra/comp restorations in NCCLs was better than that of Hv-GIC restorations. The most common problems in Hv-GIC restorations were a loss of retention and reduction in surface lustre. CLINICAL RELEVANCE: Although the 3-year clinical performance of Hv-GIC restorations in non-retentive lesions was acceptable, it was worse than in composites. The operator should consider the benefit/loss ratio of Hv-GIC when he/she decides to use this material in non-retentive cavities, especially those that are shallow.

A Randomized, Controlled, Split-mouth Trial Evaluating the Clinical Performance of High-viscosity Glass-ionomer Restorations in Noncarious Cervical Lesions: Two-year Results.

PURPOSE: To compare the two-year clinical performance of high-viscosity glass ionomer (Hv-GIC) restorations in noncarious cervical lesions with nanohybrid composite restorations applied with a three-step etch-and-rinse adhesive (E&Ra/nanoC). MATERIALS AND METHODS: One hundred thirty-four noncarious cervical lesions were included and assigned to two groups according to the split-mouth design. The cervical lesions in the experimental group were restored with an Hv-GIC (Equia, GC), while a nanohybrid composite (G-aenial, GC) with a three-step etch-and-rinse adhesive (Optibond FL, Kerr) was applied as the control. All tested restorative materials were used according to the manufacturers' instructions. Clinical evaluation was performed after one week, six months, one year, and two years using World Dental Federation criteria. Data were analyzed using Friedman's ANOVA and Mann-Whitney U-tests (α = 0.05). RESULTS: After two years, Hv-GIC restorations had a retention rate of 91% in comparison to 100% for E&Ra/nanoC restorations. Significant differences existed between the two restorative materials solely with respect to the retention parameter after two years (p = 0.008). CONCLUSIONS: The two-year clinical performance of Hv-GIC was clinically acceptable. However, the retention of E&Ra/nanoC restorations was significantly better than that of Hv-GIC restorations after two years.

Evaluation of the Efficacy and Color Stability of Two Different At-Home Bleaching Systems on Teeth of Different Shades: A Randomized Controlled Clinical Trial.

OBJECTIVE: This randomized controlled clinical trial compared the bleaching efficacy of two different at-home bleaching systems on teeth of different shades and their color stability after a 6-month follow-up. MATERIALS AND METHODS: Ninety-two patients (777 teeth) were randomly divided into three groups: (a) negative control, (b) patients treated with a custom-made tray containing 10% carbamide peroxide (10% CP/PF) (Opalescence PF), and (c) patients treated with a pre-loaded tray containing 6% hydrogen peroxide (6% HP/Go) (Opalescence Go). Teeth in all groups were divided into three sub-groups according to the VITA Classic Shade Guide: light (A1-C1), medium dark (C2-B3), and dark (A3.5-C4). Bleaching systems were performed in accordance with manufacturers' instructions for 14 days. The color values were measured at the baseline, 10 days and 14 days of bleaching, 2 weeks, and 6 months after bleaching. Three-way ANOVA and Mann-Whitney U tests were used for statistical analysis (α = 0.05). RESULTS: Irrespective of original shade, both bleaching groups showed significantly higher ΔE* values than the control groups, and the ΔE* values were significantly higher in the 10% CP/PF groups than those in the 6% HP/Go groups (p < 0.05). In both bleaching systems, the dark teeth showed higher ΔE* values than the light teeth (p < 0.05). The ΔE* values decreased significantly only in the 10% CP/PF groups after 6 months (p < 0.05). CONCLUSIONS: Both bleaching agents produced a bleaching effect, but 10% CP/PF was more effective. CLINICAL SIGNIFICANCE: A pre-loaded tray system may be used for dental bleaching, but it is still less effective than conventional a 10% carbamide peroxide system, irrespective of the initial shade. (J Esthet Restor Dent 29:325-338, 2017).

Six-month Clinical Evaluation of a Self-adhesive Flowable Composite in Noncarious Cervical Lesions.

PURPOSE: The aim of this randomized, controlled, single-center, split-mouth clinical trial was to evaluate the clinical performance of a self-adhesive flowable composite resin (SAFC) in noncarious cervical lesions in comparison with a nanohybrid composite applied with a three-step etch-and-rinse adhesive system (E&Ra/nanoC). MATERIALS AND METHODS: Eighty noncarious cervical lesions were included and assigned to one of two groups according to the split-mouth design. The cervical lesions in the experimental group were restored with an SAFC (Fusio Liquid Dentin), while a nanohybrid composite (G-aenial) applied with a three-step etch-and-rinse adhesive system (Optibond FL) was used for the control group. Clinical evaluation was performed after 1 week and again at 6 months according to FDI criteria. Data were analyzed using Wilcoxon Signed Rank and Mann-Whitney U-tests (α=0.05). RESULTS: After 6 months, 27 of the 40 SAFC restorations were in clinically unacceptable condition due to retention failure; this corresponded to a success rate of 33% compared to the success rate of 100% for the E&Ra/ nanoC restorations (p<0.05). For other criteria examined, the difference between the two groups was only statistically significant for color and translucency (p<0.05). CONCLUSION: The clinical performance of the SAFC was found to be unacceptable after 6 months of clinical use.

clinical evaluation of enamel microabrasion for the aesthetic management of mild-to-severe dental fluorosis.

STATEMENT OF THE PROBLEM: The clinical performance of enamel microabrasion alone for aesthetic management of dental fluorosis is debatable. PURPOSE OF THE STUDY: This study aimed to compare the clinical efficacy of enamel microabrasion for the aesthetic management of mild-to-severe dental fluorosis. METHODS/MATERIALS: A total of 154 fluorosed incisors and canines in 14 patients on the basis of the fluorosis were included; the teeth were classified as mild (group I, n = 53), moderate (group II, n = 56), and severe (group III, n = 45). All teeth were treated with enamel microabrasion (Opalustre, Ultradent Products, South Jordan, UT, USA). "Improvement in appearance," "changes in brown stains," "changes in opaque white areas," and "requirement for further treatments" were assessed by using visual scale systems. The data were analyzed using nonparametric tests (α = 0.05). RESULTS: The "improvement in appearance" score was the worst for group III (p < 0.05), whereas the "changes in opaque white areas" score was the best for group I (p < 0.05). Groups II and III did not differ with respect to "changes in brown stains." The proportion of patients who needed further treatment was the highest in Group III (p < 0.05). CONCLUSIONS: The severity of fluorosis affected the clinical performance of enamel microabrasion except for its performance of removing brown stains. Increase in fluorosis severity led to increased requirements for further treatments. CLINICAL SIGNIFICANCE: The clinical performance of enamel microabrasion is affected by the severity of dental fluorosis, except for its performance of removing brown stains. Even though its performance of improving appearance decreases with the increase in severity of fluorosis, it may not only remove the fluorosis stains but also may increase the success of additional subsequent treatment.

Tensile bond strength of an aged resin composite repaired with different protocols.

PURPOSE: To evaluate the effect of different surface treatments and bonding procedures on the tensile bond strength (TBS) of resin composites repaired 6 months after polymerization. MATERIALS AND METHODS: Resin composite sticks were aged in distilled water at 37°C for 6 months. They were divided into 12 groups (n = 10) according to the combination of surface treatment/bonding procedures [none, only bur treatment, XP Bond (XPB/Dentsply/DeTrey) with/without bur, AdheSE (A-SE/Ivoclar/Vivadent) with/without bur, Composite Primer (CP/GC) with/without bur, CP after bur and acid-etching, XPB after acid etching and CP with bur, A-SE after bur and CP]. The ultimate tensile bond strength (UTS) of the resin composites was tested in intact but aged specimens. Tensile bond strengths were tested with a universal testing machine (Shimadzu). Data were analyzed using one-way ANOVA and Duncan Multiple Comparisons tests (p < 0.05). RESULTS: All repaired groups showed significantly higher TBS than the group without any sureface treatment (p < 0.05). Four groups resulted in TBS similar to those of intact resin composite UTS: A-SE, A-SE with bur, A-SE after CP with bur, and XPB after acid etching+CP with bur. CONCLUSION: Bur treatment, silane primer or etch-and-rinse adhesive application alone were not successful in the repair process of aged resin composite, whereas self-etching adhesive alone showed similar performance to the intact specimens. Combined procedures generally showed better performance: A-SE with bur, A-SE after CP with bur, and XPB after acid etching +CP with bur showed TBS similar to those of the intact specimens. It was concluded that bur roughening of the surfaces and rebonding procedures were essential for repairing aged resin composites.

Color changes of dental resin composites before and after polymerization and storage in water.

UNLABELLED: The aims of this study were to: (1) evaluate the A2 shades of various types and brands of resin composites to determine if any color differences occurred before and after polymerization and after 1 month of storage in water and (2) examine the correlation among the color changes and changes in Commission internationale de l'éclairage L*, a*, and b* values after polymerization and after 1 month of storage in water. One submicron-hybrid (Spectrum TPH3, DENTSPLY DeTrey, Milford, DE, USA), one nano-filled (Filtek Supreme XT, 3 M ESPE, St. Paul, MN, USA), three micro-hybrid (Filtek Z250, 3 M ESPE; Esthet X, DENTSPLY DeTrey; and Gradia Direct, GC, Tokyo, Japan), and five nano-hybrid (Ceram X, DENTSPLY DeTrey; Clearfil Majesty Esthetics, Kuraray, Osaka, Japan; Premise, Kerr Corporation, Orange, CA, USA; Tetric Evo Ceram, Ivoclar Vivadent, Schaan, Liechtenstein and Tetric N Ceram, Ivoclar Vivadent) light-curing resin composites were tested. The specimens (N = 10 for each composite) were prepared as discs, 12 mm in diameter and 2 mm in thickness, using round molds. The measurements were performed "before polymerization,""after polymerization," and "after 1 month of storage in water" using a contact type dental spectrophotometer (Vita Easyshade, Vident, Brea, CA, USA). The range of ΔE* values after polymerization (ΔE*1) and storage in water (ΔE*2) were 4.59 to 14.13 and 1.26 to 6.29, respectively. Nested analysis of variance and post hoc tests revealed that the type of resin composites significantly affected Δa*1, Δa*2, Δb*1, Δb*2, ΔE*2-values, whereas the brand of resin composites affected the changes in all color parameters (p < 0.05). In spite of many improvements in chemical compositions and fillers of the contemporary composites, color changes after polymerization were perceptible in all resin composites. However, color changes after storage in water were in the acceptable ranges for all resin composites except Clearfil Majesty Esthetic and Gradia Direct. CLINICAL SIGNIFICANCE: In spite of many improvements in chemical compositions and fillers of the contemporary resin composites, the color changes after polymerization were still perceptible in all the resin composites tested in this study, regardless of their types and brands. Such changes may cause esthetic problems clinically, thus should be taken into account when the shade selections are performed. Alternatively, a piece of unpolymerized resin material can be placed on, or adjacent to the tooth to be restored and polymerized to confirm the selected shade of the esthetic material.

One-year clinical evaluation of the efficacy of a new daytime at-home bleaching technique.

The aim of this study was to compare the clinical efficacy and side effects of a new daytime at-home bleaching technique (28% carbamide peroxide [CP] gel) with the overnight application of 10% CP and to determine the change of tooth color 1-year post-treatment. Twenty healthy volunteers were assigned to one of two sample groups of 10. All participants employed one of the two at-home bleaching systems: (1) the new daytime at-home bleaching system including 28% CP gel with a non-custom-fit tray (Meta Tray, Remedent, Deurle, Belgium) for 20 minutes, and (b) the conventional overnight at-home bleaching system with a 10% CP gel and a custom-fit tray (Opalescence PF, Ultradent, South Jordan, UT, USA) for 6 to 8 hours. Digital images and CIE (International Commission on Illumination) L*, a*, and b* spectrophotometric measurements were taken at baseline, after the bleaching treatment and 1-year post-treatment. Tooth and gingival sensitivity was measured with a specially designed 4-point scale. Significant differences were found in L*, a*, and b* values, between initial and post-treatment, for both bleaching systems (p < 0.05). However, no significant difference was detected between post-treatment and 1-year follow-up. The bleaching effectiveness of Opalescence PF was found to be superior to that of Meta Tray, considering the color parameter of DeltaE (p < 0.05). Meta Tray provoked less tooth sensitivity (p < 0.05), however gingival sensitivity appeared more in this group (p < 0.05). Within the limitations of this study, it can be concluded that the new daytime at-home bleaching system tested (Meta Tray) produced significant bleaching effects. However, the clinical efficacy of the overnight bleaching system was found to be superior to the daytime at-home bleaching system evaluated in this study. The whitening effect remained similar 1-year after the bleaching treatment for both at-home bleaching systems. CLINICAL SIGNIFICANCE Although the new daytime at-home bleaching system tested exhibited significant bleaching effects, overnight bleaching with a 10% CP gel resulted in a higher bleaching effectiveness than this new system. Although the participants using the new bleaching system exhibited less tooth sensitivity probably because of the reduced contact time of bleaching gel with tooth surfaces, the application of the bleaching agent with a non-customized tray provoked more gingival sensitivity in this group.

Can the hydrogel form of sodium ascorbate be used to reverse compromised bond strength after bleaching?

PURPOSE: To assess the effect of the hydrogel form of different concentrations (2.5%, 5%, and 10%) of sodium ascorbate on the shear bond strength of composite after bleaching of the enamel with 10% carbamide peroxide gel. MATERIALS AND METHODS: Sixty flat buccal enamel surfaces obtained from 30 bovine incisors were divided into 6 treatment groups: group I, control (nonbleached); group II, no antioxidant treatment after bleaching; group III, 10% sodium ascorbate solution after bleaching; group IV, 2.5% sodium ascorbate hydrogel after bleaching; group V, 5% sodium ascorbate hydrogel after bleaching; group VI, 10% sodium ascorbate hydrogel after bleaching. The specimens were bonded with Clearfil SE Bond, then thermocycled and subjected to the shear test until failure. Fracture analysis of the bonded enamel surfaces was examined using a stereomicroscope. Statistical analysis was carried out using Kruskal-Wallis and the Mann-Whitney U-test. RESULTS: While the samples that were not treated with antioxidant after bleaching (group I) demonstrated significantly lower shear bond strengths and the 10% sodium ascorbate gel group (group VI) demonstrated significantly higher bond strengths than the control group (p < 0.05), no significant differences were found between the other groups and control group (p > 0.05). Among the antioxidant groups, only the groups treated with the 10% solution and the 10% hydrogel form of sodium ascorbate (group III and VI) revealed significantly higher bond strengths than the bleached group without antioxidant (group II) (p < 0.05). Higher scores were obtained with 10% sodium ascorbate gel (group VI) when compared with the other antioxidant-treated groups (p < 0.05). CONCLUSION: Within the limitations of this study, it can be concluded that the 10% hydrogel form of sodium ascorbate may be used in clinical procedures instead of its solution form. However, using sodium ascorbate hydrogel with concentrations lower than 10% may not be as reliable as using this agent in 10% concentration for reversing the compromised bond strength.

Clinical evaluation of a two-step etch&rinse and a two-step self-etch adhesive system in Class II restorations: two-year results.

OBJECTIVE: This study evaluated the clinical performance of a two-step etch&rinse and a two-step self-etch adhesive system in Class II restorations after two years of clinical service. METHODS: Thirty-three patients with primary caries or insufficient restorations were enrolled in the study. A total of 87 Class II cavities were restored, 44 using a two-step etch&rinse adhesive system (Single Bond, 3M ESPE) and 43 cavities using a two-step self-etch adhesive (Clearfil SE Bond, Kuraray). Filtek Z250 (3M ESPE) was used as a restorative material for all the restorations. The restorations were evaluated at baseline, six months, and one and two years after placement for retention, marginal discoloration, marginal adaptation, postoperative sensitivity, secondary caries, color match and anatomical form, according to the modified Ryge criteria. RESULTS: At two years, the retention rates for Single Bond and Clearfil SE Bond were 94% and 100%, respectively, (p = 0.493). No significant differences were found between both groups for the other parameters evaluated. CONCLUSION: Both of the adhesive systems that were tested demonstrated similar clinical performance at the end of this two-year clinical trial.

Noncarious class V lesions restored with a polyacid modified resin composite and a nanocomposite: a two-year clinical trial.

PURPOSE: The purpose of this study was to compare the clinical performance of a polyacid modified resin composite and a nanocomposite applied with an antibacterial adhesive system over a period of 2 years in noncarious Class V lesions. MATERIALS AND METHODS: Twenty-four patients with at least two noncarious cervical lesions were enrolled in the study. The teeth were restored with a polyacid modified resin composite (Dyract eXtra, Dentsply DeTrey) or a nanocomposite (Filtek Supreme, 3M/ESPE). Fifty restorations of each material were placed with no marginal bevels and no mechanical retentions using an antibacterial self-etching adhesive system (Clearfil Protect Bond, Kuraray). All lesions were evaluated at baseline, 6, 12, and 24 months periods using the USPHS criteria for color match, marginal discoloration, marginal adaptation, caries formation, anatomic form, postoperative sensitivity, surface roughness, and retention. The changes across the four time points were assessed using Friedman and Wilcoxon Signed Ranks tests. The two restorative materials were compared in the same recall period for each of the criteria using chi-square test (p = 0.05). RESULTS: Dyract eXtra restorations exhibited a significantly better color match than Filtek Supreme restorations; however, all restorations in both groups were clinically acceptable. Filtek Supreme's retention rate (100%) was found to be significantly better than that of Dyract eXtra (96%). Two Dyract eXtra restorations were completely lost while one was partially fractured (p < or = 0.05). Significant differences were observed in marginal adaptation and color match of Filtek Supreme restorations and marginal discoloration of Dyract eXtra and Filtek Supreme restorations between the baseline and the 2-year scores (p < or = 0.05). CONCLUSION: Both restorative materials showed acceptable clinical performance in Class V noncarious lesions after 2 years of clinical service.

Effect of different laser devices on the composition and microhardness of dentin.

This study determined the compositional changes and microhardness of the cavity floor prepared by Er,Cr:YSGG and Er:YAG lasers and compared the results with the conventional method of bur preparation. Fifteen non-carious human molars were used in this study. On the buccal and lingual surfaces of each tooth, two cavities (mesio-distal 3 mm, inciso-gingival 3 mm, depth 2 mm) were prepared with two different laser devices (Er,Cr:YSGG laser; Waterlase MD and Er:YAG laser; KaVo Key Laser 3) and a high-speed turbine. The teeth were embedded into polyester resin and cross-sectioned. The microhardness measurements from the floor of each half cavity were recorded with the Vickers surface hardness tester. The remaining halves of the cavities were subjected to SEM-EDS atomic analysis. The results were statistically evaluated by one-way ANOVA and Kruskal Wallis tests (p = 0.05). No significant differences were observed among the microhardness values, quantities of Ca (Ca weight %), P (P weight %) and Ca/P ratio of the lased and conventionally prepared cavities (p > 0.05). The cavity preparation techniques and differences in laser devices did not significantly alter the composition and microhardness of dentin tissue. Both laser devices used in this study were observed to lead to minimal thermal damage in the dentin tissue and minimal thermally-induced changes in dentinal compositions.

Can different chlorhexidine agents be used as cavity disinfectants?

This study used the agar well method to compare the antimicrobial effect of cavity disinfectants containing chlorhexidine with other chlorhexidine agents (such as mouthrinses and antiseptics) and to determine whether there was a difference in composite bond strength when these chlorhexidine agents were applied to the dentin surface. All tested solutions showed antimicrobial effect against Streptococcus mutans, Lactobacillus acidophilus, and Candida albicans (p < 0.05). However, Savlex was found to be the most effective antibacterial agent against all microorganisms (p < 0.05). There were no significant differences between the bond strengths obtained from the cavity disinfectants and those of the control group (p > 0.05). However, the mouthrinse and the antiseptic decreased the shear bond strength compared with the control group (p < 0.05).

Microleakage study of different adhesive systems in Class V cavities prepared by Er,Cr:YSGG laser and bur preparation.

This study sought to compare the microleakage of composite resin restorations using two different dentin adhesive systems and two different modes of cavity preparation: a high-speed handpiece and an Er,Cr:YSGG laser. Twenty-five caries-free permanent human premolars were assigned randomly into five groups of five. A high-speed handpiece was used to prepare Class V cavities on the buccal and lingual surfaces of 10 randomly selected teeth. Class V cavities were cut on the buccal and lingual surfaces of the remaining 15 teeth using the Er,Cr:YSGG laser system. Fifty cavities were prepared with enamel and dentin margins 1.0 mm below the cemento-enamel junction and assigned into five groups: I, II, and III by the Er,Cr:YSGG laser and IV and V by the high-speed handpiece. In all groups, the differences between gingival and occlusal leakage scores were statistically significant (p < 0.05). The occlusal and gingival scores of groups I and IV demonstrated statistically significant differences (p < 0.05). The lased group with additional acid etching revealed less microleakage than groups III and IV (p < 0.05). Both self-etch and total-etch adhesive systems demonstrated acceptable microleakage scores when used on Er,Cr:YSGG laser-prepared cavities; however, additional acid etching after Er,Cr:YSGG laser preparation is recommended.

Bacterial microleakage of barrier materials in obturated root canals.

The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarboxylate cement, resin modified glass ionomer cement, and flowable composite resin) used as a base over obturated root canals were evaluated during a 5-month period. Sixty single-rooted mandibular premolars were obturated with cold lateral compaction of gutta-percha. The teeth were randomly divided into five groups of 10 teeth each and positive and negative control groups of five. The access openings were filled with one of the tested barrier materials in four groups. In group 5, no barrier material was placed. Samples were incorporated in a model system using Staphylococcus epidermidis as a microbial marker. Results were analyzed with Kaplan-Meier survival analysis (p = 0.05). The sealing ability of all tested materials was better when compared with group 5 (no barrier material) (p < 0.05). Within the limitations of this study, the glass ionomer cement leaked significantly less when compared with the flowable composite resin (p < 0.05).

Shear bond strength of different adhesives to Er:YAG laser-prepared dentin.

PURPOSE: The aim of this study was to examine the influence of Er:YAG laser on the shear bond strength of three different adhesives to lased dentin. MATERIALS AND METHODS: Seventy specimens obtained from 35 extracted human molars were embedded in polyester resin and ground with silicon carbide papers. The samples were divided into seven groups. 1. Er:YAG laser (Key Laser 3, KaVo) + Clearfil Protect Bond (Kuraray); 2. Er:YAG laser + Clearfil tri-S Bond (Kuraray); 3. Er:YAG laser + 37% H3PO4 + Single Bond 2 (3M-ESPE); 4. Er:YAG laser + Single Bond 2; 5. conventional method + Clearfil Protect Bond; 6. conventional method + Clearfil tri-S Bond; 7. conventional method + 37% H3PO4 + Single Bond 2. The samples were subjected to shear bond testing 24 h after bonding. Statistical analyses were carried out by two-way ANOVA, t-test, one-way ANOVA, post-hoc Tukey's and Dunnett C test (p = 0.05). RESULTS: Only the Er:YAG laser + Clearfil tri-S Bond group demonstrated significantly higher bond strengths vs conventionally prepared specimens (p < 0.05). There were no significant differences between the shear bond strengths of Single Bond 2 adhesive applied to laser- vs bur-treated specimens (p > 0.05). In laser prepared samples, Clearfil Protect Bond showed the highest scores (p < 0.05), whereas in conventionally prepared groups, no statistical differences were observed between Clearfil Protect Bond and Clearfil tri-S Bond (p > 0.05). CONCLUSION: Er:YAG laser irradiation did not adversely affect the shear bond strength of Single Bond 2 and Clearfil Protect Bond to dentin, whereas it increased the shear bond strength values of Clearfil tri-S Bond.

Bactericidal effect of Er,Cr:YSGG laser on Streptococcus mutans.

The aim of this study was to compare the antibacterial activities of Er,Cr:YSGG laser with two different power outputs against a chlorhexidine gluconate-based cavity disinfectant. A cavity tooth model test was used to determine the antibacterial activity. Four cylindrical cavities were prepared on the dentin surface of 10 bovine incisors and left in contact with Streptococcus mutans for 72 hours to allow bacterial invasion. Following which, Er,Cr:YSGG laser with 0.75 W and 1 W power outputs and a chlorhexidine gluconate-based cavity disinfectant were applied separately on one of the three infected cavities, whereas the fourth was left untreated for control. Standardized amounts of dentin chips were obtained from the cavity walls, and the number of bacteria recovered was counted. Statistical analysis was carried out using one-way ANOVA and Dunnett's C test (p=0.05). No significant differences were observed among the data obtained from the chlorhexidine gluconate-based cavity disinfectant and the two Er,Cr:YSGG laser groups (p>0.05). However, when compared to the control group, both Er,Cr:YSGG laser groups and the chlorhexidine gluconate-based cavity disinfectant resulted in significantly less bacterial recovery (p<0.05). In conclusion, the antibacterial activity on S. mutans demonstrated by Er,Cr:YSGG laser with both energy outputs was similar to that of the tested chlorhexidine gluconate-based cavity disinfectant.