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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.

A Five-Year Clinical Evaluation of Direct Nanofilled and Indirect Composite Resin Restorations in Posterior Teeth

AIM To assess the clinical efficacy of posterior composite resin restorations placed directly and indirectly in posterior teeth after five years. MATERIALS AND METHODS A total of 108 cavities in 54 patients were restored with three direct composite resins (Filtek SupremeXT [FSXT], Tetric Evo Ceram [TEC], AELITE Aesthetic [AA]) and two indirect composite resins (Estenia [E] and Tescera ATL [TATL]). All restorations were evaluated by two examiners using the United States Public Health Service criteria at baseline and five years after placement. Statistical analysis was completed with Fisher exact and McNemar χ(2) tests. RESULTS At baseline, 4% (five) of the restored teeth presented postoperative sensitivity; however, only one of them (a member of the E group) required canal treatment and replacement after two years. At the five-year evaluation, all restorations were retained, with Alpha ratings at 100%. Only one tooth (in the TEC group) required replacement after three years due to secondary caries. Color match, surface texture, and marginal integrity were predominantly scored as Alpha after five years for all groups. After that time, marginal discoloration was scored as Alpha in 64% of AE restorations, 70% of TATL restorations, 73% of E restorations, and 87% of FSXT restorations. There were no Charlie scores recorded for any of the restorative systems. CONCLUSIONS Under controlled clinical conditions, indirect composite resin inlays and direct composite resin restorations exhibited an annual failure rate of 2.5% and 1.6%, respectively, after five years. Therefore, the investigated materials showed acceptable clinical performance, and no significant differences were found among them.

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.

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).

An In Vitro Comparison of Different Diagnostic Methods in Detection of Residual Dentinal Caries

The aim of this study was to investigate the efficiency of different diagnostic methods in detection of residual dentinal caries in excavated cavities. Fifty extracted molar with deep dentinal carious lesions were excavated using a slow-speed handpiece. All cavities were assessed by laser fluorescence(LF) device, electronic caries monitor(ECM), and caries detector dye(CDD) by three independent observers blindly. The measurements were repeated after two weeks. Specimens containing dentin slices 150 μm in thickness were prepared for histological analyses. The existence and absence of carious dentin was determined using a lightmicroscope. The average intraobserver accuracy was 1.00 (perfect agreement) for CDD, 0.86 (excellent agreement) for ECM, and 0.50 (good agreement) for LF. The average interobserver accuracy values were 0.92 (excellent agreement), (0.36 marginal agreement) and 0.48 (good agreement), for CDD, ECM, and LF, respectively. The average specificity was 0.60 for CDD, 73% for ECM, and 0.50 for LF. The average sensitivity was 0.55 for CDD, 0.85 for LF, and 0.47 for ECM. The average accuracy values were 0.53, 0.51, and 0.81 for CDD, ECM, and LF, respectively. LF had the greatest sensitivity and accuracy values of any of the methods tested. As a conclusion, LF device is appeared to most reliable method in detection of remain caries in cavity. However, because of its technical sensitivity it may susceptible to variations in measurements. To pay attention to the rule of usage and repeated measurements can minimize such variations in clinical practice. It was concluded that LF is an improvement on the currently available aids for residual caries detection.

Bond Strength of Self-etch Adhesives After Saliva Contamination at Different Application Steps

This study evaluated and compared the effect of saliva contamination and possible decontamination methods on bond strengths of two self-etching adhesive systems (Clearfil SE Bond [CSE], Optibond Solo Plus SE [OSE]). Flat occlusal dentin surfaces were created on 180 extracted human molar teeth. The two bonding systems and corresponding composite resins (Clearfil AP-X, Kerr Point 4) were bonded to the dentin under six surface conditions (n=15/group): group 1 (control): primer/bonding/composite; group 2: saliva/drying/primer/bonding/composite; group 3: primer/saliva/rinsing/drying/primer/bonding/composite; group 4: primer/saliva/rinsing/drying/bonding/composite; group 5: primer/bonding (cured)/saliva/rinsing/drying/primer/bonding/composite; group 6: primer/bonding (cured)/saliva/removing contaminated layer with a bur/rinsing/drying/primer/bonding/composite. Shear bond strength was tested after specimens were stored in distilled water at 37°C for 24 hours. One-way analysis of variance and Tukey post hoc tests were used for statistical analyses. For CSE, groups 2, 3, and 4 and for OSE, groups 6, 2, and 4 showed significantly lower bond strengths than the control group (p<0.05). CSE groups 5 and 6 and OSE groups 3 and 5 revealed bond strengths similar to the control. When saliva contamination occurred after light polymerization of the bonding agent, repeating the bonding procedure recovered the bonding capacity of both self-etch adhesives. However, saliva contamination before or after primer application negatively affected their bond strength.

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 Dunns 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.

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

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.

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.

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.