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.     

Effects of various irrigation solutions on microleakage of Class V composite restorations

STATEMENT OF THE PROBLEM: Irrigation solutions used in the preparation of composite restorations have been reported to contain potential contaminants that may interfere with, and compromise, composite bonding. PURPOSE: The purpose of this in vitro study was to evaluate microleakage of Class V composite restorations after irrigation of acid conditioner with various solutions. MATERIAL AND MENTODS: Standardized Class V preparations (5 mm wide, 4 mm high and 2 mm deep) were made at the cemento-enamel junction on available buccal, lingual, mesial, and distal surfaces of extracted human posterior teeth. The prepared teeth, separated into 7 groups (n=10), were etched for 10 seconds with a 37% phosphoric acid gel. Each group was irrigated with 1 of the following solutions: (1) tap water, (2) sterile water, (3) sodium chloride solution, (4) filtered water, (5) chlorhexidine, (6) sodium hypochlorite, and (7) distilled water. Each preparation was treated with a bonding agent (Opti-Bond Solo) and then restored with a hybrid composite (Herculite XRV). The restorations were polished with Soflex polishing disks and then thermal cycled for 1000 cycles between 5 degrees C and 55 degrees C with a 20-second dwell time. Assessment of microleakage was performed by application of a dye penetrant, sectioning of the teeth, and examination at original magnification x 20. The nonparametric Kruskal-Wallis test (alpha=.05) was used for statistical analysis. RESULTS: Microleakage ranging from 10% to 30% was observed in all groups tested. Tap water exhibited the highest incidence of leakage, sterile water the least, with the other irrigation solutions leading to intermediate leakage. However, there was no significant difference in microleakage resulting from any of the irrigation solutions tested. CONCLUSION: The effect of irrigation solutions used in this in vitro study was not significant.     

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 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.     

Effect of eccentric load cycling on microleakage of Class V flowable and packable composite resin restorations.

Class V composite restorations are subject to the stresses that induce non-carious cervical lesions. This study evaluated the effect of eccentric oblique load on microleakage of restorations. Class V cavities were randomly prepared on the buccal surfaces of 40 recently extracted premolars and restored with composite resin according to manufacturers' directions. Teeth were randomly assigned to one of four treatment groups with 10 teeth per group: (1) flowable resin (Revolution) without load cycling; (2) packable resin (Prodigy Condensable) without load cycling; (3) flowable resin with load cycling (200,000 cycles) and (4) packable resin with load cycling (200,000 cycles). All teeth were then immersed in 2% methylene blue solution for 24 hours after thermocycling (500 cycles). Dye penetration was measured (scores 0-3). The results indicated that adding load cycling significantly increased microleakage (p < 0.05). No significant differences in microleakage were observed for flowable resin vs packable resin. Gingival margins had significantly more microleakage (p < 0.05) than occlusal margins.     

In vitro evaluation of microleakage of a flowable composite in Class V restorations

The aim of this study was to evaluate microleakage around class V restorations using a flowable composite compared to a hybrid composite. Forty class V cavities were prepared on buccal and lingual surfaces of 20 human teeth, with occlusal and cervical margins at the enamel and cementum/dentin levels, respectively. Specimens were divided into 2 groups with 10 samples each. Group 1: buccal cavities received Paama 2 (conventional bonding agent) + Wave (flowable composite); lingual cavities were restored with Paama 2 + Glacier (hybrid composite). Group 2: buccal cavities received Optibond Solo (self-priming bonding agent) + Wave; lingual cavities were restored with Optibond Solo + Glacier. After being stored in distilled water and finished, the teeth were thermocycled, immersed in a 50% silver nitrate solution and embedded in resin. They were sectioned and the depth of tracer penetration was scored. The results were analyzed using Kruskal-Wallis and Wilcoxon tests. The restorations with flowable composite and those with hybrid composite from the same group showed similar results of microleakage for both occlusal and cervical margins. Optibond Solo improved the sealing of the restorations when compared with Paama 2 (p < 0.01). None of the restorative materials completely sealed the tooth/restoration interface at the cervical margins.     

The effects of high concentration tooth whitening bleaches on microleakage of Class V composite restorations

OBJECTIVE: To explore the effects of high-concentration hydrogen peroxide bleaching agents on the microleakage of composite restorations. METHODS: In 60 extracted human molars, Class V restorations were prepared with Scotchbond 1/Filtek Z250 composite. Teeth were randomly divided into four groups: (1) no bleaching; (2) bleaching with 14% hydrogen peroxide gel from Crest Whitestrips; (3) bleaching with 20% carbamide peroxide gel from Opalescence PF 20; and (4) bleaching with 38% hydrogen peroxide gel Opalescence Xtra Boost. Bleaching procedures were carried out at 37 degrees C for 21 days/42 hours (2); seven days/42 hours (3); one day/45 minutes (4). Varnish was applied on the apical portion of the teeth only, excluding the restoration, prior to immersion in a 0.1% rhodamin-B-isothiocyanate solution for 24 hours at 37 degrees C. After rinsing, specimens were embedded in methacrylate blocks, and sectioned with a water-cooled microtome with three restoration cuts positioned centrally parallel to the long axis of the tooth. Microleakage was evaluated at the occlusal margins of the Class V restorations using a stereo microscope, separate for dentin and enamel margins. RESULTS: Over 90% of enamel margins exhibited no microleakage following cycling. Bleaching agents had almost no effect on numerical averages. Eighty-eight percent of the dentin margins were free of microleakage for the non-treated control group. Bleaching treatments collectively had slight numerical reductions to around 80%. The statistical evaluation (Kruskal-Wallis-test) showed no significant difference in microleakage between groups for enamel or dentin. CONCLUSION: Bleaching with the materials tested had no influence on microleakage of Filtek Z250 composite bonded with Scotchbond 1.     

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.     

Influence of light intensity and curing cycle on microleakage of Class V composite resin restorations

The aim of this study was to determine the effect of a softstart polymerization method from Quartz-Tungsten-Halogen (QTH) and Plasma Arc (PAC) curing units on microleakage of Class V composite resin restorations with dentin cavosurface margins. Seventy-five bovine incisors received standardized class V cavities in all dentin margins. Teeth were divided into 5 equal groups according to the curing cycle. The cavities were incrementally restored with a composite resin (Single Bond/Z-100, 3M). Light curing was applied as follows: Group I: PAC light continuous-cycle curing at 1600 mW/cm2 for 3s; Group II: PAC light step-cycle curing (2s at 800 mW/cm2 then 4s at 1600 mW/cm2); Group III: QTH light continuous-cycle curing at 400 mW/cm2 for 40s; Group IV: QTH light ramp-cycle curing (from 100 to 600 mW/cm2 in 15s followed by 25s at 600 mW/cm2); Group V: QTH light pulse-delay curing (200 mW/cm2 for 3s followed by 3 min delay then 600 mW/cm2 for 30s). Teeth were stored in distilled water at 37oC for 30 days and then subjected to thermocycling for 500 cycles at 5 and 55oC. Root apices were sealed and teeth coated with nail varnish before they were immersed in 0.5% fuchsine red dye solution. Teeth were then sectioned and slices were scanned with a computer scanner to determine the area of dye leakage using a computer program (Image Tools). Images of tooth slices were also visually examined under magnification and dye penetration along the tooth/restoration interface was scored. Significant differences in the degree of dye penetration and leakage were detected between groups (p<.05). Groups I and II had significantly higher values of dye penetration and leakage than groups III, IV and V. In conclusion, the use of PAC light curing in a continuous or step cycle modes resulted in increased microleakage of Class V resin composite restorations compared with medium intensity QTH light curing. Pulse, ramp and continuous-cycle curing modes with QTH light resulted in similar degrees of microleakage.     

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 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).     

The effect of thermocycling on microleakage of several commercially available composite Class V restorations in vitro

STATEMENT OF THE PROBLEM: Microleakage is a major factor contributing to the occurrence of secondary carious lesions around composite restorations. PURPOSE OF STUDY: This in vitro study investigated the effect of thermocycling on microleakage of several composite Class V restorations. MATERIAL AND METHODS: One hundred twenty molars were randomly distributed into 6 groups of 20 teeth. Class V preparations were made in the buccal and lingual surfaces of each tooth and restored in bulk by use of 6 composites (Arabesk, Silux-Plus, Solitaire 2, Durafill VS, Charisma, and Renew) according to the manufacturers' recommendations. The teeth were stored in distilled water at room temperature for 24 hours. The teeth in each group were divided randomly into 2 subgroups: (a) thermocycled for 500 cycles between 5 degrees and 55 degrees C with a dwell time of 30 seconds, (b) no thermocycling treatment. All restored teeth were immersed in 1% methylene blue dye for 4 hours and sectioned buccolingually with a diamond wheel. Dye penetration was scored by use of a stereomicroscope at original magnification x4. The generalized linear models statistical analysis was used (alpha=.05). RESULTS: The preparation margins (enamel/dentin) and thermocycling had a significant effect on microleakage (P=.0351, P<.0001, respectively); the type of material had no significant effect (P=.1689). CONCLUSIONS: Thermocycling significantly increased the microleakage (P<.0001). The overall microleakage at the enamel margins was significantly less than at the dentinal margins (P=.0351).     

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.     

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.     

Factors associated with microleakage in Class II resin composite restorations

This in vitro study investigated the correlation between factors related to cavosurface marginal adaptation and microleakage in Class II cavities restored with a light- or chemical-activated resin composite. Standardized cavities were prepared in 40 molars that were randomly divided between both materials. Each of the groups was, in turn, divided, so that the restorations were placed by incremental and bulk techniques. The resultant four groups (n = 10), each with material/technique variations, had their marginal gaps measured by environmental scanning electron microscopy at randomly selected facial and lingual points of the proximal box of each restoration. After sectioning the teeth, interfacial dye penetration was assessed by light stereomicroscopy according to an ordinal scale at the same locations as for the marginal gaps. In a general linear model with microleakage as a dependent variable, no correlation between marginal gap size and microleakage was found (p = 0.802), although the interaction of the material and placement technique (p = 0.028) and material alone (p = 0.063) influenced microleakage. The model explained 63% of the variation in microleakage. It was concluded that, irrespective of the possible role of marginal gap in the occurrence of microleakage, the choice of material and placement technique are important determining factors in microleakage.