Effect of four intermediate layer treatments on microleakage of Class II composite restorations

This in vitro study examines the marginal sealing ability of four different intermediate materials applied before placement of a condensable composite. Class II preparations were made with gingival margins placed 1.0 mm apical to the cementoenamel junction of 60 extracted teeth, randomly assigned to five groups of 12. Following restoration, teeth were thermocycled, soaked in 0.5% basic fuchsin, and sectioned longitudinally. The resin-modified glass ionomer cement demonstrated significantly less microleakage than the use of a dentin bonding agent alone or in combination with flowable composite, flowable compomer, or autoploymerizing composite (p < 0.05, Dunn's test). This study supports the use of the glass ionomer open sandwich technique in deep Class II direct composite restorations.     

Effect of non-vital tooth bleaching on microleakage of coronal access restorations

This study evaluated the effect of non-vital tooth bleaching on microleakage of composite resin/bovine tooth interface at different post-bleaching times. A total of 320 teeth were cleaned. A pulp chamber access cavity was made at the lingual surface of each tooth. The teeth were randomly divided into four groups: SPH - sodium perborate + 30% hydrogen peroxide; SPW - sodium perborate + distilled water; CP-37% carbamide peroxide; and CON-distilled water (control). The bleaching agents were replaced every 7 days, over 4 weeks. Following bleaching procedures, the groups were divided into four subgroups (n = 20), according to the post-bleaching times: 0 (baseline), 7, 14 and 21 days. After that, the cavities were restored with an adhesive system (Single Bond; 3M Co., St Paul, MN, USA) and a composite resin (Z100/3M). The specimens were thermocycled, stained with 2% methylene blue solution (pH 7), and sectioned longitudinally. The teeth were evaluated blind and independently by three previously calibrated examiners, to provide representative scores. The data were submitted to Kruskal-Wallis and multiple comparison tests (alpha=0.05). At baseline and 7 days, the SPH group showed a higher degree of dye penetration than the CON (P=0.04). At 14 and 21 days, there were no differences among groups. The association of sodium perborate with 30% hydrogen peroxide or with water may affect the sealing ability of composite resin restorations performed up to 7 days after bleaching procedures.     

Effect of dentin deproteinization on microleakage of Class V composite restorations

The role of the collagen fibers in dentin adhesion has not clearly been established. Therefore, this laboratory study evaluated the microleakage at resin-dentin and resin-enamel interfaces of Class V composite restorations after etching enamel and dentin with phosphoric acid (H3PO4) or after etching with H3PO4 followed by deproteinization with 5% sodium hypochlorite (NaOCl) to prevent the formation of a hybrid layer. Ten extracted human molars were used to prepare standardized Class V cavities on both buccal and lingual surfaces. The teeth were randomly divided in two groups: 1) Class V cavities that were etched with H3PO4 for 15 seconds; b) Class V cavities that were etched with H3PO4 for 15 seconds followed by collagen removal with 5% NaOCl for two minutes. The cavities were restored using the Prime & Bond 2.1 bonding system and TPH resin composite. The specimens were stored in water for 24 hours at 37 degrees C and thermocycled 500 times between water baths kept at 5 degrees C and 55 degrees C. After thermocycling, specimens were immersed in a 0.5% aqueous solution of basic fuchsin for 24 hours. Three longitudinal sections of each restoration were obtained and examined with a stereomicroscope for qualitative evaluation of microleakage. The data were statistically analyzed by Mann-Whitney U and Wilcoxon matched pairs signed ranked tests. Extra specimens were analyzed with the scanning electron microscope (SEM). Occlusal margins (enamel margins) resulted in statistical lower degree of leakage than gingival margins (dentin/cementum margins) in both treatment groups. For each type of margin, there were no statistically significant differences between the etched and the etched and deproteinized groups. Under the SEM, occlusal surfaces showed no detachment between enamel and dentin, while dentin/cementum resulted in gap formation.     

In vitro microleakage of composite restorations after nonvital bleaching.

OBJECTIVE: After bleaching treatment, esthetic restorations often need to be replaced due to color changes. Some papers have shown alterations in the bond of adhesive restorations to bleached teeth. The purpose of this study was to evaluate tooth and resin composite adhesion when submitted to nonvital dental bleaching. METHOD AND MATERIALS: One hundred and twenty bovine teeth were assigned to 3 groups (n = 40); paste of sodium perborate and water; 37% carbamide peroxide gel; and no bleaching (control). After 3 weeks of continuous bleaching treatment, standardized Class V cavities were prepared at the cementoenamel junction and restored with Single Bond adhesive system and Z100 resin composite. The samples were thermocycled 1,500 times (5 +/- 1/55 +/- 1 degrees C) with a 1-minute dwell time. Then, they were immersed in a 2% methylene blue solution (pH 7) for 4 hours, sectioned, and analyzed by stereomicroscopy. Microleakage analyses were done, using scores from 0 to 4, considering leakage on the incisal wall (enamel) and the cervical wall (dentin). Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (alpha = 0.05). RESULTS: The results showed that sodium perborate and carbamide peroxide gel significantly increase the microleakage in Class V resin composite restorations to dentin but not to enamel margins. CONCLUSION: The risk of microleakage in dentin margins is increased soon after bleaching treatment.     

Effect of bonding application time on the microleakage of Class V sandwich restorations

Background: The aim of this study was to assess the effect of bonding application time on the microleakage of Class V sandwich restorations. Methods: Eighty non‐carious third molars were randomly divided into 16 groups. Two Class V cavities were prepared on the buccal and lingual surfaces of teeth. Three groups were restored with Fuji II GIC and treated with a total‐etch bonding system (Stea/SDI) immediately after insertion, at 7 minutes and 15 minutes after mixing the glass ionomer cements (GICs). Another three groups were restored with Riva Self Cure GIC and treated with the total‐etch system identically. The other six groups were subjected to self‐etching bonding (Frog/SDI) after GIC placement in an identical procedure. The remaining groups were made using light cure GICs (Fuji II or Riva Light Cure) in conjunction with the total‐etch or self‐etching systems. Cavities were then restored with composite (Valux plus, 3M/ESPE). Samples were subsequently immersed in 2% methylene blue solution for 48 hours and observed under a stereomicroscope after sectioning. Four‐scale grading was used to assess microleakage in occlusal and gingival walls. Data were analysed using Kruskal–Wallis and Mann–Whitney tests. Results: The self‐etching bonding system exhibited more microleakage in occlusal margins regardless of time. Over time, microleakage significantly decreased in gingival margins in all self‐cure groups except for Riva Self Cure treated with the total‐etch system (p < 0.05). Conclusions: Bonding application time had no effect on the microleakage of occlusal margins. However, maturation of GICs induced a decreased microleakage in gingival margins.     

Effect of bonded amalgam restorations on microleakage

The purpose of this study was to evaluate quantitatively the effectiveness of adhesive dentin bonding systems in decreasing microleakage at the tooth-amalgam restoration interface. The results indicated that microleakage was significantly reduced when Amalgambond Plus or All-Bond 2 was used as liners in comparison to either Copalite varnish or no linear under amalgam restorations. No significant difference was found between the two dentin bonding systems at all time periods studied.     

Effect of LED curing on microleakage and microhardness of Class V resin-based composite restorations

BACKGROUND: Polymerisation shrinkage is a critical limitation of dental composites and may contribute to microleakage, postoperative pain, tooth fracture, and secondary caries. It has been shown that curing methods play a significant role in polymerisation shrinkage of light-cured dental resins. The purpose of this study was to investigate the effect of a LED curing light on microleakage as well as microhardness of a dental composite. METHOD: For the microleakage test 32 Class V cavities were prepared in human premolars, conditioned with 35% phosphoric acid and treated with the bonding agent Prime & Bond NT. They were then incrementally filled with the composite Esthet-X and randomly divided into two groups of 16 each. The first group was cured by means of a Spectrum 800 set at 500 mW/cm2 for 40 seconds and the second group with the GC E-Light in standard mode. The specimens were thermo-cycled in a 0.5% basic fuchsin solution, sectioned and evaluated for dye penetration. For the microhardness test two groups of 6 specimens each were exposed using either the LED- or the Halogen curing unit. Vickers microhardness tests were performed immediately after curing as well as 24 hours later, on the top, and at the bottom surface. RESULTS: At the dentine/cementum interface, significantly less microleakage (p=0.004) was found when the restorations were cured with the LED-unit. At the enamel interface no significant difference (p=0.340) in microleakage was found between curing methods. Immediately after exposure significantly harder surfaces were found at the top (p<0.001) as well as at the bottom (p<0.001), using the halogen unit (p<0.05). CONCLUSION: Although a reduction in microleakage could be demonstrated exposing the composite restoration to an LED LCU, an effective microhardness ratio was not achieved.     

Prerestorative bleaching: effect on microleakage of Class V cavities.

The effect of bleaching extracted teeth on the microleakage of subsequently placed Class V composite resin restorations was evaluated. Ten extracted premolars were stored in water at 37 degrees C to serve as controls. Ten premolars were exposed to a carbamide peroxide gel for three 2-hour periods per day for 9 days. These specimens were stored in water at 37 degrees C except during treatment periods. Class V cavity preparations were then placed at the cementoenamel junction of the facial and lingual surfaces of all teeth. Half of the teeth of each group were restored with Scotchbond 2/Silux Plus and half were restored with Prisma Universal Bond 3/AP.H. After 24 hours of storage in 37 degrees C water, the teeth were thermally stressed for 100 cycles. Microleakage was assessed by dye penetration. The results demonstrated that prerestorative bleaching did not affect the marginal seal of subsequently placed restorations.     

Relationship between bond strength and microleakage measured in the same Class I restorations.

Microleakage measurements were made by use of a pressurized fluid method in Class I restorations prepared in extracted human teeth just prior to measuring the tensile bond strengths of the same restorations. The restorative materials included dentin bonding systems that are applied to smear layers as well as those which remove the smear layer. A light-cured glass-ionomer cement was also included. The results demonstrated that there was an inverse relationship between dentin bond strength and microleakage in some materials and that the bond strengths made to three-dimensional Class I cavities were much lower than those made to flat dentin surfaces. Measurement of microleakage by fluid filtration had no apparent effect on bond strength.     

Effect of centripetal and incremental methods in Class II composite resin restorations on gingival microleakage

AIM: The aim of this study was to evaluate the microleakage at gingival margins below the cementoenamel junction (CEJ) of Class II composite restorations using various placement techniques. METHODS AND MATERIALS: Sound human maxillary premolars were selected. Eighty slot-style cavities on the mesial or distal surfaces were prepared with the cervical margins located apical to the CEJ. The specimens were divided into two groups based on the restorative technique utilized (centripetal or incremental). Each group was then categorized into two subgroups according to the type of matrix used resulting in a total of four experimental groups as follows: IP=Incremental and Palodent matrix, IT = Incremental and Transparent matrix, CP= Centripetal and Palodent matrix, and CT = Centripetal and Transparent matrix. Following restoration with a total etch adhesive (Single Bond) and a resin composite (Z100), the teeth were thermocycled. Then specimens were immersed in 0.5% basic fuchsin dye for 24 hours at a temperature of 37 degrees C. Sectioned restorations were examined under a stereomicroscope (40X magnification), and the extent of the microleakage was scored and recorded. Data were analyzed using the Kruskal-Wallis non-parametric statistical test (P=0.05). RESULTS: In the four groups of the study no significant differences in the mean rank of microleakage were observed (p>0.05). CONCLUSION: When the gingival margin was located on cementum, the kind of matrix and filling technique did not reduce the microleakage.     

Effect of insertion technique and adhesive system on microleakage of Class V resin composite restorations

PURPOSE: To evaluate the effect of different insertion techniques and adhesive systems on microleakage of Class V composite resin restorations. MATERIALS AND METHODS: Forty-eight human molars were randomly assigned to four groups (n = 12). Standardized mixed Class V cavities (enamel and dentin margins) were prepared at the CEJ. A total-etch (Adper Scotchbond MultiPurpose) and a self-etching (iBond) adhesive system were evaluated using either an incremental or single-step (bulk) insertion technique. The preparations were restored with Esthet*X micromatrix hybrid composite. The teeth were thermocycled 1000 cycles, immersed in 1% methylene blue dye for 24 h, and invested in acrylic resin. The specimen blocks were then sectioned longitudinally, with dye penetration (microleakage) examined with a 20X binocular microscope. Enamel and dentin margins were scored separately for microleakage using an ordinal ranking system. Results were analyzed using non-parametric tests at a p < 0.05 level of significance. RESULTS: Significance was exhibited between the groups (adhesive material/insertion technique) at the coronal and apical margins. At the coronal margin, the total-etch adhesive/incremental insertion group exhibited significantly less leakage than the other groups, while at the apical margin, the total-etch adhesive/incremental insertion group showed significantly less leakage than the self-etching adhesive/bulk insertion group. Significantly less leakage was found at the coronal margins compared to the apical margins of the material/technique groups. CONCLUSION: The use of a total-etch adhesive system and incremental insertion of composite significantly reduced microleakage at the coronal and apical margins of Class V composite restorations.     

Effect of flowable composite lining on microleakage and internal voids in Class II composite restorations

PURPOSE: The aim of this study was to determine the influence of four flowable composite linings on marginal microleakage and internal voids in Class II composite restorations with the margins above the cementoenamel junction (CEJ). MATERIALS AND METHODS: Class II cavities were randomly divided into 8 groups (n = 10). Group 1: One Step Plus/Aelite LS Packable; group 2: One Step Plus/Aelite Flow/Aelite LS Packable; group 3: Comfort Bond/Solitaire 2; group 4: Comfort Bond/Flowline/Solitaire 2; group 5: Solobond M/Grandio; group 6: Solobond M/Grandio Flow/Grandio; group 7: Admira Bond/Admira; Group 8: Admira bond/Admira Flow/Admira. After restoration, all teeth were stored for 24 h, thermocycled (at 5 degrees C to 55 degrees C) 500 times, and soaked in 0.5% basic fuchsin dye for 24 h. After soaking, the teeth were sectioned and observed under a stereomicroscope. Gingival marginal microleakage and internal voids (at the gingival wall interface and in the cervical and the occlusal parts) were recorded. Data were analyzed with the Mann-Whitney U- and Kruskal-Wallis tests (p < 0.05). RESULTS: Statistical analyses indicated that the use of flowable resin composites provided a reduction in microleakage in groups 6 and 8. Groups 2 and 4 showed fewer voids in the cervical area than without flowable composites. CONCLUSION: It was concluded that none of the materials tested was able to eliminate the marginal microleakage on the cervical wall. Flowable resin composites under nanohybrid (group 6) and ormocer (group 8) composites provided a significantly different reduction in microleakage compared to restorations without flowable liners. Fewer cervia voids were observed in packable composites with flowable liner (groups 2 and 4) than without flowable liner (groups 1 and 3s).     

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).     

Quantitative microleakage evaluation around amalgam restorations with different treatments on cavity walls

The purpose of this in vitro study was to evaluate the dye penetration around amalgam restorations in dentin cavities by a quantitative test. Standardized circular cavities were prepared on the facial surface of 75 extracted human single-rooted teeth, and restored with dental amalgam. Different bonding/sealing treatments were used on the cavity walls before the restorations were placed. The specimens were thermo-cycled between 5 +/- 2 degrees C and 55 +/- 2 degrees C for 500 cycles with 1-minute dwell times, followed by immersion in a 2% methylene blue solution for 12 hours at 37 degrees C. The quantitative microleakage was evaluated by spectrophotometry and was expressed by microgram dye per tooth structure. The results showed that the use of bonded amalgam restorations was more effective in reducing microleakage.     

Effect of surface roughness of cavity preparations on the microleakage of Class V resin composite restorations

This study determined whether surface roughness of the internal walls of a Class V resin composite preparation, using a carbide bur, a medium-grit diamond bur and a fine-grit diamond bur, affected the degree of microleakage of the restoration. The facial and lingual surfaces of 45 non-carious extracted human molars provided 90 samples for evaluation. The specimen surfaces were assigned randomly in equal numbers to one of three groups (n = 30). Conservative Class V composite preparations were made using one of three different burs: a 330-carbide bur, a 330 fine-grit diamond bur or a 330 medium-grit diamond bur (Brasseler USA). After acid etching, PQ1 (Ultradent Products Inc) primer/bonding resin and Vitalescence (Ultradent Products Inc) were applied and cured following the manufacturers' instructions. After minor finishing, the apices of all root surfaces were sealed with Vitrebond (3M), and the unprepared external surfaces were sealed with nail polish to within 1 mm of the restoration margins. The specimens were stored in distilled water at room temperature for 24 hours, then subjected to 1,200 thermocycles at 5 degrees C and 55 degrees C with a 30-second dwell time. After cycling, the teeth were immersed in a 5% solution of methylene blue dye for 12 hours. The molars were invested in clear acrylic casting resin, labeled, then sectioned once vertically approximately midway through the facial and lingual surfaces using a diamond coated saw blade. Microleakage was evaluated using a 10x microscope for the enamel and cementum surfaces and blindly scored by two independent examiners. In all cases, regardless of the examiner, at both the enamel and the dentin margins, the analysis revealed no statistically significant differences in microleakage across bur types. Further results show that dentin margins leaked significantly more than enamel margins for all bur types.     

Margin quality and microleakage of Class II composite resin restorations

Margin quality and isotope microleakage analyses of Class II restorations placed in extracted human molars were compared using various composite resins and placement techniques. At occlusal margins, the traditional (experimental) composite resin restoration placed by the incremental technique showed less microleakage than did the traditional (commercial) [corrected] composite resin restoration placed by the bulk technique. In each group, the occlusal and proximal adaptations had significantly higher "excellent margin" than did the cervical adaptation. Thus, the marginal adaptation at the cervical aspect of conventional Class II composite resin restorations may present a problem with respect to microleakage.