The improvement of biocompatibility of adhesives : The effects of resveratrol on biocompatibility and dentin micro-tensile bond strengths of self-etch adhesives.

OBJECTIVE: The aim of this in vitro study is to evaluate the effects of resveratrol (RES) addition on the cytotoxicity and microtensile bond strength (µTBS) of different adhesives. MATERIALS AND METHODS: Five self-etching adhesives (G-aenial Bond-GC, Optibond All in One-Kerr, Gluma Self Etch-Kulzer, Clearfil S3 Bond-Kuraray, and Nova Compo-B Plus-Imicryl) were tested. They were applied to L-929 cell culture by the extract method. In the test groups, 0.5 µM RES (Sigma-Aldrich) was added into the medium. Cell viability was assessed by MTT assay after 24 h. Human extracted third molars were used for µTBS test (n = 7). The adhesives with or without 0.5 µM RES addition were applied on dentin surfaces. A composite build-up was constructed. Then, the specimens were sectioned into multiple beams with the non-trimming version of the microtensile test and subjected to microtensile forces. Statistical analysis was performed using ANOVA and post hoc Tukey test (p Ë‚ 0.05). RESULTS: The extracts of all adhesives decreased the cell viability. However, RES addition increased the cell viability in all groups (p Ë‚ 0.05). RES addition did not cause any decrease in µTBS values of the adhesives compared to baseline. Optibond All in One showed the highest µTBS after RES addition. It was followed by Clerafil S3 Bond and Nova Compo-B Plus. No difference was determined between the Optibond All in One and Clearfil S3 Bond. There was difference between Optibond All in One and Nova Compo-B Plus (p Ë‚ 0.05). CONCLUSION: RES addition may improve the biocompatibility without causing negative influence on µTBS of the adhesives. CLINICAL RELEVANCE: RES addition has clinical applicable potential to overcome the adverse biocompatibility of adhesives.

Bond strengths of a self-etching adhesive to dentin surfaces treated with saliva, blood, and different hemostatic agents.

The aim of this study was to evaluate the microtensile bond strengths of a self-etching adhesive to dentin surfaces after treatment with 4 different hemostatic agents in the presence of saliva and blood. After testing, no significant differences were found between the mean bond strength of Clearfil SE (CSE) Bond resin adhesive to normal dentin and those of CSE to dentin treated with the hemostatic agents ViscoStat Clear, Astringedent, or Astringedent X (P > 0.05). However, the mean bond strength of CSE Bond to dentin treated with Ankaferd Blood Stopper (ABS) was significantly greater than those of the other groups (P < 0.05). Thus, while 3 of the tested hemostatic agents did not have significant effects on the bond strength of composite resin to dentin, ABS increased the bond strength of CSE Bond to dentin.

The effect of prophylactic polishing pastes on surface roughness of indirect restorative materials.

The purpose of this study was to evaluate the influence of prophylactic polishing pastes (PPP; Detartrine (DT), Topex (TP)) on surface roughness (R(a)) of indirect composites (IRC; Tescera (TES), Gradia (GRD), and Estenia C&B (EST)), a glass ceramic (Empress 2 layering (E2)), and a leucite reinforced glass ceramic (Empress Esthetic (EE)) with two different (glazed (G); polished (P)) surface preparations. A total of 90 IRC and 120 ceramic discs, 8 mm in diameter and 2 mm thick, were prepared. E2 and EE specimens were randomly divided into two groups (n = 30). One group was glazed (GE2; GEE), while the other group was polished (PE2; PEE) the same as the IRCs. The specimens in each group were subsequently divided into three subgroups: control (C), DT, and TP. R(a) (µm) was evaluated with a profilometer. Data were analyzed by Kruskal Wallis, followed by the Dunn's multiple comparison tests (P < 0.05). DT and TP resulted in significant surface roughening for TES, GRD, and EST, while no significant differences were detected between DT and TP (P > 0.05). PE2 and PEE were not affected by DT or TP (P > 0.05), while GE2 and GEE exhibited significant roughening after TP (P < 0.05). Surface roughness of IRCs and glazed ceramics can be affected by PPP applications.

Factors influencing the longevity of posterior composite restorations: A dental university clinic study.

Objectives: This retrospective study aimed to assess the performance of posterior composite resin restorations (PCRRs) and evaluate the influence of patient-specific factors on restoration outcomes. Methods: A total of 189 PCRRs were examined in 54 patients, with evaluations based on Modified USPHS criteria. Patient-specific factors were analyzed. Statistical analyses, including chi-square tests, independent samples t-tests, and ANOVA tests, were conducted. Results: Patients aged over 50 exhibited higher DMFT averages and a higher rate of unsuccessful restorations. Despite higher DMFT scores in females, gender doesn't significantly impact restoration outcomes. Secondary caries correlated with.plaque scores, significantly affecting restoration survival. Marginal adaptation, retention deficiencies, and secondary caries were primary causes of failure. Multi-surface restorations faced higher failure risk due to elevated plaque scores. Class-V restorations showed a higher failure rate, challenging the number of surfaces and longevity correlation. Conclusions: This study identified key factors influencing posterior composite resin restorations-(PCRRs) in patients over 50, including higher DMFT averages and more unsuccessful restorations. No significant difference was found between brushing; frequency and DMFT rates, possibly due to the absence of non-brushers. Secondary caries; correlated with elevated plaque scores, impacting restoration survival. Primary causes of; failure included marginal adaptation issues, retention deficiencies, and secondary caries, with multi-surface restorations facing a higher risk. However, tooth vitality, beverage and acidic food consumption, and oral hygiene habits did not significantly affect PCRR outcomes. Clinical significance: Patient-specific factors significantly impact PCRRs' long-term performance. Dentists must tailor strategies, emphasizing regular monitoring and preventive measures for extended survival.

The effect of a modeling resin and thermocycling on the surface hardness, roughness, and color of different resin composites.

STATEMENT OF PROBLEM: The application of modeling resin could affect the surface quality and color of resin composites. PURPOSE: To evaluate the effects of modeling resin on the microhardness, roughness, and color of composite restorations, with and without thermocycling. METHODS: Sixty disc-shaped specimens for each resin composite were prepared in three groups: Group 1: A resin composite disc was cured against a polyester matrix and finished/polished; Group 2: A composite instrument was wetted with Bisco Modeling Resin (Bisco, Schaumburg, IL, USA) to smooth the composite surface, which was cured against a polyester matrix and finished/polished; Group 3: A composite instrument was wetted with modeling resin to smooth the composite surface, which was cured against a polyester matrix. Microhardness, roughness, and color were measured 24 hours after curing and after 10,000 thermocycles. RESULTS: Modeling resin significantly influenced the microhardness of GrandioSO (Voco, Cuxhaven, Germany) and Gradia Direct Posterior (GC America, Alsip, IL, USA), and the surface roughness of GrandioSO, Filtek Silorane (3M ESPE, St Paul, MN, USA), and Aelite All Purpose Body (Bisco) (p < 0.05). The microhardness of the Group 1 resin composites was affected by thermocycling (p < 0.05); however, thermocycling had no significant effect on surface roughness (p > 0.05). Tested composites showed clinically perceptible color changes after thermocycling. In Group 1, Filtek Ultimate (3M ESPE) showed the lowest color change (p < 0.05), and in Group 2, Filtek Silorane showed the highest significant color changes (p < 0.05). CONCLUSIONS: Modeling resin did not affect the microhardness, surface roughness, and color of Aelite LS Posterior (Bisco), Filtek Ultimate (3M ESPE), and Clearfil Majesty Esthetic (Kuraray Medical Inc, Tokyo, Japan) specimens. Also, thermocycling process only affected microhardness of tested resin composites. CLINICAL SIGNIFICANCE: The effect of modeling resin on surface microhardness, roughness, and color stability of composite materials depends on the type of resin composite. In clinical practice, the adverse effects of modeling resin might be alleviated by a proper finishing and polishing procedure.

Influence of operator experience on in vitro bond strength of dentin adhesives.

PURPOSE: To examine the influence of operator experience level on shear bond strength (SBS) of a self-etching adhesive (Clearfil SE Bond [CSE], Kuraray) and an etch-and-rinse adhesive (Single Bond [SB], 3M ESPE). MATERIALS AND METHODS: Flat dentin surfaces were created on 120 extracted human third molars. Bonding agents and composite resin were applied and light cured according to manufacturers' directions (n = 15). Four operators with different levels of experience in operative dentistry performed the same specimen preparation steps independently: group 1: specialist in operative dentistry; group 2: post-graduate student; group 3: undergraduate dental student; group 4: private general practitioner. Specimens were stored in distilled water for 24 h at 37°C before SBS testing. Statistical analyses were carried out with Mann-Whitney U- and Kruskall-Wallis tests. RESULTS: For CSE, mean SBS and standard deviations were: (1) 54.4 ± 15.6(a), (2) 55.3 ± 7.6(a), (3) 49.4 ± 10.5(ab), (4) 41.6 ± 13.1(b). For SB, they were: (1) 28.6 ± 10.3(c), (2) 32.7 ± 11.2(c), (3) 17.5 ± 5.6(d), (4) 24.4 ± 9.5(cd). Groups with the same superscript letters are not significantly different. CSE showed higher bond strengths than SB in all groups (p < 0.05). There was no significant difference in mean bond strengths between groups 1 and 2 for each adhesive (p > 0.05). Depending on the adhesives, groups 3 and 4 were significantly different from groups 1 and 2, but not different from each other. CONCLUSION: Operator experience influences dentin bond strength values of dentin adhesives. An increased level of experience with a specific adhesive system and the associated application procedures correlates with higher SBSs.

In vivo and in vitro evaluations of microleakage around Class I amalgam and composite restorations.

This study evaluated and compared microleakage values of in vivo and in vitro placed Class I amalgam restorations with or without three different lining materials and posterior composite restorations with two dentin bonding agents. For the in vivo group, 72 standardized Class I cavities were prepared on the occlusal surfaces of molars scheduled for extraction. The test groups (n = 12) were: amalgam without lining (A), amalgam with cavity varnish (A+C), amalgam with Clearfil SE Bond (A+CSE), amalgam with Clearfil 2V (A+C2V), composite with Clearfil SE Bond (C+CSE) and composite with Protect Bond (C+PB). The restored teeth were extracted after seven days. The same grouping, materials and techniques were used in 72 extracted molars for the in-vitro part of the study. The specimens were immersed in basic fuchsin for 24 hours and sectioned. Microleakage was examined and scored at 20x magnification. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney U-tests with the 5% level of significance. Overall, the in vivo and in vitro test groups were not different from each other. No significant differences in microleakage values were observed between the unlined and lined amalgam groups (p > 0.05). However, since lined amalgam restorations did not reveal any marginal leakage, the application of an adhesive bonding material under the amalgam restorations can be considered. In general, cavity varnish was not as effective as adhesive bonding agents in preventing microleakage in amalgam restorations. Composite restorations demonstrated higher leakage values than amalgam restorations (p < 0.05), except for A+C (p > 0.05) in the in vivo group. There was no significant difference between the two composite groups for in vitro and in vivo conditions (p > 0.05).

One-year clinical evaluation of direct nanofilled and indirect composite restorations in posterior teeth.

The aim of this study was to assess the clinical performance of three direct composite resins and two indirect inlay systems in posterior teeth using the modified USPHS criteria. A total of 100 restorations were placed in the molars of 54 patients by one operator. All restorations were directly evaluated by two examiners at baseline, 6 months, and 12 months. Statistical analysis was conducted using McNemar chi-square test at a significance level of 5% (p<0.05). Recall rate was 100% at 6 and 12 months, and all the restorations evaluated (i.e., 100%) received Alpha rating for the criteria of retention and gingival adaptation. At 12 months for the surface texture criterion, 80% of Filtek Supreme XT received Alpha rating while it was 95% for Tetric EvoCeram and AELITE Aesthetic. For marginal discoloration, 85% of Tescera ATL and Filtek Supreme XT received Alpha rating while it was 95% for Tetric EvoCeram and AELITE Aesthetic. Further, none of the restorative systems received a Charlie rating for any of the criteria at all evaluation periods. In summary, all the restorations demonstrated clinically satisfactory performance with no significant differences detected among them.

The effect of different restoration techniques on the fracture resistance of endodontically-treated molars.

AIM: This study compared the fracture resistance of endodontically-treated mandibular molars with mesio-occluso-distal (MOD) cavities restored using different restoration techniques. METHODOLOGY: Sixty sound extracted mandibular molars were randomly assigned to six groups (n=10). Group 1 did not receive any preparation. The teeth in Groups 2-6 received root canal treatment and a MOD cavity preparation. The teeth in Group 2 were kept unrestored. Group 3 was restored conventionally with amalgam. Group 4 was restored with a dentin bonding system (DBS, Clearfil SE Bond) and resin composite (CR) (Clearfil Photoposterior). Group 5 was restored with indirect hybrid ceramic inlay material (Estenia). In Group 6, polyethylene ribbon fiber (Ribbond) was inserted into cavities in a buccal-to-lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens, except for Group 2, were loaded to failure by a chewing simulation device (60,000 cycles x 50 N load, 1.3 Hz frequency) in an artificial environment at 37 degrees C. Each tooth was subjected to compressive loading perpendicular to the occlusal surface at a crosshead speed of 1 mm/minute. The mean loads necessary to fracture were recorded in Newtons and the results were statistically analyzed. RESULTS: The mean fracture values were as follows: Group 1: 2485.3 +/- 193.98a, Group 2: 533.9 +/- 59.4a, Group 3: 1705.8 +/- 135.7a, Group 4: 2033.3 +/- 137.6cd, Group 5: 2121.3 +/- 156.5d, Group 6: 1908.9 +/- 132.2cd. There were statistically significant differences between the groups annotated with different letters. Thus, Group 1 (intact teeth) had the greatest fracture resistance and Group 2 (non-restored teeth) the poorest. No statistically significant differences were found between Groups 3 (amalgam), 4 (resin composite) and 6 (polyethylene ribbon fiber reinforced composite) (p > 0.05). Group 5 (indirect hybrid ceramic inlay) had greater fracture resistance than Group 3 (p < 0.05). CONCLUSIONS: Within the limitations of this study, although all of the restoration groups were stronger than the prepared-only group, none of the restoration techniques tested was able to completely restore the fracture resistance lost from MOD cavity preparation. However, use of indirect hybrid inlay restorations in these teeth may be recommended, because this restoration technique indicated more favorable fracture failure modes than other restoration techniques used in this study and particularly greater fracture strength than amalgam restorations. The promising result of indirect hybrid inlay restorations may need to be confirmed by long-term clinical studies.

Bond strengths of three different dentin adhesive systems to sclerotic dentin.

The two-fold aims of this study were: (1) to evaluate the microtensile bond strengths of different adhesive systems to sclerotic and sound palatal dentin; and (2) to observe the respective resin-dentin interfaces. Thirty extracted human incisor teeth were divided into two groups. Group I comprised sclerotic defects in the palatal zone. Group II comprised sound palatal dentin surfaces as control. Each group (n=15) was divided into three subgroups according to dentin adhesive systems: self-etch (Clearfil SE Bond), total-etch (Scotchbond Multi-Purpose Plus), and glass ionomer (Reactmer Bond) adhesive systems. The specimens were subjected to tensile forces. Obtained data were analyzed by two-way ANOVA and post hoc Duncan's test. Fracture sites and resin-dentin interfaces were observed using a light microscope and SEM. With sound dentin, Clearfil SE Bond showed a significantly higher bond strength than the other adhesives (p < 0.05). With sclerotic dentin, although there were no significant differences in bond strength among the adhesives groups (p > 0.05), the bond strength values of Clearfil SE Bond and Scotchbond Multi-Purpose Plus were significantly decreased. On resin-dentin interface observation, different images were presented by different bonding systems.

Effectiveness of different preventive agents on initial occlusal and proximal caries lesions: A follow-up study.

BACKGROUND/PURPOSE: Monitoring the effects of different caries-preventive agents on initial caries lesions in orthodontic patients is important. Therefore, the purpose of this study is to investigate the efficacy of different preventive methods in preventing occlusal and proximal incipient lesions (ILs) during fixed orthodontic treatment. MATERIALS AND METHODS: Forty-eight subjects at the beginning of fixed orthodontic treatment were included. All subjects were well educated and motivated to use the fluoride toothpaste (Colgate Total, 1450 ppm F) three times a day during the study period. Four different groups were created with a split-mouth design: placebo, fluoride gel, fluoride varnish, and chlorhexidine varnish. The occlusal surfaces of the second molar teeth were assessed with DIAGNOdent pen (DD) during the first 12 months (6th and 12th), and the proximal surfaces of each quadrant were monitored using bitewing radiographs until the 24th month (baseline and 24th month). RESULTS: The mean DD values increased in each group during the first 6 months compared to the baseline, but a significant increment was only obtained in the control and fluoride gel groups (p < 0.05). Fluoride and chlorhexidine varnish had significantly more preventive effects than the control and the fluoride gel for occlusal surfaces at the 6th and 12th month and for intact proximal surfaces at the 24th month, but no significant differences were found between the two varnish groups (p > 0.05). No significant differences were found between the four methods in terms of caries progression for proximal ILs after 24 months. CONCLUSION: Effective toothbrushing with 1450 ppm fluoridated toothpaste and topical fluoride gel application seems to be inadequate for prevention of new proximal ILs during fixed orthodontic treatment. Fluoride and chlorhexidine varnish showed more protection in relation to occlusal surfaces.

Effectiveness of Different Preventive Programs in Cariogram Parameters of Young Adults at High Caries Risk.

OBJECTIVE: To evaluate the effectiveness of different preventive programs in young adults at high caries risk using Cariogram software. METHODS: Sixty-six young adults with high caries risk were evaluated. Dental caries risk for all subjects was determined according to WHO criteria. Subjects were divided into three different preventive groups (control: OH, fluoride varnish: FV, and chlorhexidine varnish: CV). They were followed for 12 weeks (baseline: T0, 1 week: T1, 4 weeks: T2, and 12 weeks: T3). Plaque index, diet frequency, and salivary chairside tests (to record the flow rate, buffer capacity, and mutans streptococci and lactobacillus counts) were performed at each visit. Based on these data, ten caries-related variables were collected and inserted into the Cariogram software to calculate the predicted chance of avoiding caries for each subject. RESULTS: Significant changes were obtained about the Cariogram parameters (diet, bacteria, susceptibility, circumstances, and Cariogram risk group). No significant differences were found between the three methods regarding mean Cariogram scores after 3 months (p > 0.05). CONCLUSIONS: The regular and effective short-term (three months) use of 1450 ppm fluoridated toothpaste, one visit application of fluoride, and chlorhexidine varnishes were effective for reducing caries risk in young adults, which can be clearly demonstrated using Cariogram software.

Effects of different desensitizers and lasers on dentine tubules: An in-vitro analysis.

BACKGROUND: Dentin hypersensitivity is an important clinical problem affecting a large percentage of the population, and various therapies have been suggested for its treatment-among them desensitizing agents and lasers. The aim of this study was to evaluate the in vitro effects of different in-office desensitizing agents and different type lasers, alone or in combination, on human dentinal tubules. MATERIALS AND METHODS: Eighty-four dentinal specimens obtained from freshly extracted impacted third molars were included and subsequently divided into seven groups: Group 1 (Control), Group 2 (Gluma desensitizer), Group 3 (Teethmate desensitizer), Group 4 (Nd:YAG laser), Group 5 (Er:YAG laser), Group 6 (Gluma desensitizer + Er:YAG laser), and Group 7 (Teethmate desensitizer + Er:YAG laser). The dentinal specimens of all groups were evaluated using SEM. A total of 12 images per sample were taken, and the numbers of open, partially occluded, and totally visible (open + partially occluded) dentinal tubules were counted. AFM was used to further substantiate the blocking mechanism. The data were analyzed by one-way ANOVA and Dunnett-C tests. RESULTS: Comparison of the number of occluded dentinal tubules per 100 µm2 revealed that the laser and laser combined-treated groups showed the most occluded dentinal tubules. Gluma desensitizer + Er:YAG laser combination demonstrated significantly more tubule occlusion than all the other groups (p < .05). CONCLUSIONS: The results of this study show that combined treatment methods were effective in the occlusion of dentinal tubules.

Dental findings in marfan syndrome: a case report.

Marfan syndrome is an autosomal dominant disorder of connective tissue primarily characterized with anomalies affecting the musculoskeletal system, the cardiovascular system and the eyes. It has been suggested that early diagnosis of the syndrome is important, because of the risk of infective endocarditis. A 7-year-old female was referred to our clinic, with a chief complaint of dental crowding in the anterior region of mandible. It was observed that the patient needed multiple treatments based on detailed clinical and radiographic examinations. The treatment was carried out with antibiotic prophylaxis an hour prior to her appointment considering her profound caries. The patient was advised to visit regularly for follow up and she was referred for orthodontic evaluation.

Treatment of post-orthodontic white spot lesions with CPP-ACP paste: A three year follow up study.

To determine the efficacy of topical applications of 10% casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste in reverting white spot lesions (WSLs) after fixed orthodontic treatment. Forty one participants were randomly assigned to either the test group (CPP-ACP) or the control group (only fluoride toothpaste). All patients used regular fluoride-containing toothpaste. CPPACP paste or fluoridated toothpaste was applied on to tooth surfaces with WSLs twice a day during 36-month after de-bonding. The labial/buccal surfaces of teeth were assessed by use of DIAGNOdent pen (DD), Gorelick Index and ICDAS II criteria at baseline (T1) and 36-month (T2) follow-up visits. The total counts of Streptococcus mutans and Lactobacillus were obtained at T1 and T2. DMFT, DMFS, stimulated flow rate and buffer capacity were calculated in two appointments. Daily usage of CPP-ACP paste was not better than normal care for improving the appearance of WSLs after 36 months.

Three-year clinical evaluation of fiber-reinforced composite fixed partial dentures using prefabricated pontics.

PURPOSE: The purpose of this study was to evaluate the clinical performance of surface-retained adhesive composite fixed partial dentures reinforced by an ultra-high molecular weight polyethylene (UHMWP) fiber (Ribbond THM). MATERIALS AND METHODS: Twenty-three surface-retained fiber reinforced composite (FRC) fixed partial dentures (FPD) were placed by two operators in 23 patients, each with a single missing tooth. The restorations included prefabricated composite resin pontics, and no preparations were done on the lingual surfaces of the abutment teeth. The patients were recalled for examinations every year for up to 3 years. Restorations were evaluated directly using the modified Ryge criteria. The minimum observation period was 1 year and the maximum observation period was 3 years. RESULTS: At baseline, 23 restorations were graded as Alpha for all parameters. At one year and two years (n = 21), three Bravos for wear resistance and surface texture/gingival inflammation and two Bravos for color match were observed. Twenty-one of 23 restorations were retained at the end of two years (91.3%) and 78.3% were retained after a maximum of 3 years. CONCLUSION: The results of this clinical study suggestthat UHMWP FRC FPDs are quite acceptable at least forthree years. However, further clinical investigations are still needed for improved long-term clinical performance.

Microtensile bond strength of two resin composite materials placed with direct and indirect techniques under simulated pulpal pressure.

PURPOSE: The aim of this in vitro study was to compare the dentin bond strength of directly and indirectly inserted composite restorations. MATERIALS AND METHODS: Twenty extracted human mandibular molars were prepared to form a flat occlusal dentin surface using an Isomet saw under water. Five-mm-thick composite restorations (Filtek Z 250 and Clearfil AP-X) were placed on the dentin surfaces by direct or indirect techniques. The direct restorations were bonded with Single Bond and Clearfil SE Bond bonding agents. Indirect restorations were cemented with two composite luting cements (3M Opal Luting Cement and Panavia F). All restorative procedures were applied under simulated pulpal pressure (15 cm H2O). Each tooth was then vertically sectioned with an Isomet saw through the composite buildups and the dentin. Thus, for microtensile testing, 0.65 x 0.65 mm specimens were obtained from pulpal and remote dentin regions. The results were analyzed according to the regional dentinal surfaces (pulpal and remote dentin). For statistical analyses, two-way ANOVA and Duncan post-hoc tests were used (p < 0.05). RESULTS: Direct application of Clearfil AP-X showed that tensile bond strengths were higher than those obtained for directly and indirectly applied Filtek Z 250 and indirectly applied Clearfil AP-X. No significant difference in tensile bond strengths was demonstrated between pulpal and remote dentin (p > 0.05). CONCLUSION: It is concluded that the bond strengths of resin luting cements to dentin need further improvement.

Effect of home bleaching agents on the roughness and surface morphology of human enamel and dentine.

AIMS: Carbamide peroxide (CP) containing bleaching agents are now widely used in different concentrations. In this study, the effect of 10% and 15% CP containing home bleaching agents on the surface roughness and morphology of human enamel and dentine were evaluated in vitro. METHODS: 90 non-carious human mandibular incisors were divided randomly into two equal groups (enamel and dentine). The dentine group specimens were ground to expose dentine surfaces. The samples in both groups were then randomly divided into three main groups and then divided into three subgroups, according to bleaching application times (n=15). The samples in both enamel and dentine groups were treated with 10% CP at Group 1 and 4, 15% CP at Group 2 and 5 and distilled water at Group 3 and 6. The surface roughness of the samples was analysed before bleaching (1a, 2a, 3a for enamel, 4a, 5a, 6a for dentine), after 4hr (1b, 2b, 3b for enamel, 4b, 5b, 6b for dentine) and after 28hr of bleaching application (1c, 2c, 3c for enamel, 4c, 5c, 6c for dentine) using a computerised roughness tester. The surface morphologies of treated and control specimens were also examined by SEM. RESULTS: There were no statistically significant differences between the surface roughness of untreated control specimens and the specimens treated with the bleaching materials (10% and 15% CP) for both enamel and dentine at any given measurement time (p>0.05). CONCLUSION: Under the careful guidance of a dentist, home bleaching can be thought a reliable treatment for both stained enamel and dentine, regardless of whether 10% or 15% CP is used.

Reducing microleakage in composite resin restorations: an in vitro study.

The purpose of this in vitro study was to evaluate the effect of a resin lining on microleakage around composite resin restorations. Standard slot cavities were prepared on the approximal surfaces of 48 extracted human molar teeth. The cavities were restored with two conventional or two condensable composite resins, placed with or without a flowable composite resin lining. The teeth were subjected to thermal stress and immersed in dye solution. Dye penetration was viewed with both a stereomicroscope and a scanning electron microscope. Flowable resin lining material under condensable composites may be beneficial in reducing microleakage around cervical margins.

Clinical wear rate of direct and indirect posterior composite resin restorations.

The purpose of this randomized clinical trial was to determine the clinical wear behavior of three nanofilled composites (Filtek Supreme XT [FS], Tetric EvoCeram [TEC], and Aelite Aesthetic [AA]) with two indirect composites (Estenia [E] and Tescera ATL [TATL]) on permanent molar teeth. Fifty-four patients whose treatment plans included moderate Class I and/or II restorations on molar teeth were selected for inclusion in this study. Wear was measured by use of gypsum replicas at baseline and 6 and 12 months using three-dimensional scanning and rapid-form software to elucidate the wear mechanisms. For statistical analyses, one-way analysis of variance and the Scheffe test were used. Statistical results revealed that wear behavior of TATL was significantly different from that of AA (P < .05). No significant differences were detected between AA and E (P > .05) or between TEC, FS, and TATL composite resins (P > .05). The results showed similar clinical performance between the five composite resins evaluated. Therefore, composite resins may be indicated for the restoration of posterior teeth. However, the composition of the composite resin did affect the wear behavior of the composite material.