Factors affecting microleakage of a packable resin composite: an in vitro study

This study was designed to determine the effects of three factors on the microleakage of a packable resin composite: different adhesive systems (single-step self-etching adhesive or total-etch and one-bottle adhesive), the use of a flowable resin composite (as a liner) and the different techniques of cavity preparation. Sixty extracted non-carious human first and second molars were selected and randomly divided into six groups. Cervical cavities were prepared using the conventional technique on the distal sides and the air-abrasive technique was used on the mesial sides of the teeth. The experimental groups were restored with PQ1 + SureFil or Prompt L-Pop + SureFil with or without PermaFlo. In the control groups, only SureFil was used on 10 teeth and PermaFlo + SureFil was applied on the remaining 10 teeth. The restored teeth were stored in 100% humidity at 37 degrees C for 24 hours and thermocycled between 5 degrees C and 55 degrees C for 100 cycles. Each tooth was immersed in India ink for 48 hours, then sectioned. Dye penetration at the occlusal and gingival margins was scored by two independent operators. The data were statistically analyzed to assess the differences between the test and control groups. No significant differences among the adhesives in terms of the occlusal margins of the cavities were observed. However, PQ1 led to less microleakage compared to Prompt L-Pop at the gingival margins (p < 0.0062). When flowable resin composite was used with Prompt L-Pop, microleakage was reduced (p < 0.0125). However, no significant difference was observed between the two cavity preparation techniques (p > 0.0125).     

Use of a compomer in Class V restoration: a microleakage study.

OBJECTIVE: The purpose of this investigation was to evaluate the microleakage of Class V lesions restored with a compomer material (Dyractflow) using 2 single-bottle bonding systems. METHOD AND MATERIALS: Sixty-four Class V cavity preparations were made on 32 sound, extracted human premolars, 1 preparation on the facial surface and 1 on the lingual surface. Teeth were then randomly divided into 2 groups. Group 1, which served as the control group, was restored as follows: group 1a, facial surface with PQ1 single-bottle bonding system plus TPH resin composite; group 1b, lingual surface with Prime & Bond NT single-bottle bonding system plus TPH. Group 2 was restored as follows: group 2a, facial surface with PQ1 plus Dyractflow compomer material; group 2b, lingual surface with Prime & Bond NT plus Dyractflow. After 24 hours of storage in water and subsequent thermocycling, each specimen was immersed in 0.2% basic fuchsin dye for 24 hours. The teeth were sectioned longitudinally and horizontally, and dye penetration at enamel and cementum margins was viewed at x30 magnification by 2 independently calibrated evaluators. Specimens were evaluated as either having leaked or not having leaked. RESULTS: No statistically significant differences in microleakage were noted between group 1 and group 2 specimens. CONCLUSION: Both single-bottle bonding systems, PQ1 and Prime & Bond NT, demonstrated equal effectiveness in reducing microleakage beneath compomer and composite restorations.     

Effect of finishing time and techniques on marginal sealing ability of two composite restorative materials

STATEMENT OF PROBLEMS: Finishing of composites may adversely influence the sealing ability of direct adhesive restorations. PURPOSE: This study was conducted to determine whether finishing time and techniques under wet or dry conditions affect the microleakage of 2 types of class V composite restorations. MATERIAL AND METHODS: Eighty class V preparations were made in the buccal surfaces of noncarious molars with the occlusal margins ending in enamel and the gingival margins in dentin. Dental adhesive (Single Bond) was applied according to the manufacturer's instructions. Half of the preparations were restored with a microfilled composite (Silux Plus) and the other half with a hybrid composite (Filtek Z250). Within each major composite group (n = 40), 4 subgroups (n = 10) were established based on finishing technique (diamond finishing burs or aluminum oxide discs) and finishing time (immediate or delayed by 24 hours). The specimens were stored for 24 hours in 37 degrees C water, thermocycled for 250 cycles between 5 degrees C and 55 degrees C, immersed in 2% methylene blue solution for another 24 hours, and sectioned longitudinally. For both enamel and dentin margins, dye solution penetration at the tooth/composite interface was scored from 0 to 4 under stereoscopy at original magnification x 20. Data were analyzed with the Kruskal-Wallis test (P<.05). RESULTS: Significantly lower leakage scores were recorded for teeth restored with microfilled composite and finished under wet conditions after 24 hours (P<.01). No significant differences were found among the hybrid composite groups. CONCLUSION: For microfilled composite restorations on dentin margins, delayed wet finishing with diamond burs resulted in significantly lower microleakage scores than all other finishing protocols. Hybrid composite restorations had equivalent levels of microleakage regardless of the finishing method.     

The effects of soft-start vs continuous-light polymerization on microleakage in Class II resin composite restorations

PURPOSE: Despite the different light sources and polymerization techniques developed to eliminate it, microleakage of resin composite still remains a problem. This in vitro study was designed to compare the effects of exponential mode soft-start polymerization with those of standard and high-intensity continuous light polymerization on microleakage in Class II resin composite restorations. MATERIALS AND METHODS: Standardized Class II cavities (4 mm wide, 4 mm long, 5 to 6 mm high, 2 mm deep) were prepared in 50 extracted human molars. Specimens were divided into 5 groups (n = 10) and restored using the same hybrid resin composite (Z250), but separately polymerized by one of five different methods: group 1: continuous halogen light polymerization for 40 s; group 2: continuous high-intensity halogen light polymerization for 10 s; group 3: exponential mode soft-start halogen light polymerization for a total of 40 s; group 4: continuous LED light polymerization for 40 s; Group 5: exponential mode soft-start LED light polymerization for a total of 40 s. All specimens were thermocycled for 1000 cycles at 5 degrees C to 55 degrees C and then placed in 0.5% basic fuchsin dye for 24 h. Specimens were then rinsed, embedded in resin and sectioned longitudinally. Dye penetration at occlusal and cervical margins was rated using a scale of 0 to 4. Data was analyzed using Kruskal-Wallis and Mann-Whitney U-tests. RESULTS: Significantly lower marginal leakage was recorded with exponential mode soft-start polymerization when compared to continuous light polymerization. No significant differences in microleakage were observed between LED and halogen light polymerization. CONCLUSION: Within the limits of this in vitro study, the use of the soft-start exponential mode of LED and/or halogen light units in the polymerization of hybrid composite was found to produce significantly lower microleakage at both occlusal and cervical margins when compared to continuous light polymerization methods.     

Microleakage evaluation of a new low-shrinkage composite restorative material

PURPOSE: This study compared the microleakage of an experimental low-shrinkage resin composite (Hermes), a nanofilled resin composite material (Filtek Supreme) and a hybrid resin composite (Tetric Ceram) using a dye penetration method. METHODS AND MATERIALS: Class I cavities prepared in 60 human molars were randomly divided into 3 groups according to the restorative material used. The preparations were restored using a bulk or an incremental technique. Half of the specimens from each group were subjected to 200,000 cycles of loading at 50 N, while the other half were stored in distilled water for 24 hours at 37 degrees C. All specimens were immersed in 1% methylene blue (pH = 7.0) for 24 hours and sectioned into 3 slabs. The margins were evaluated for microleakage using an ordinal scoring system (0-4) under a stereomicroscope at 40x magnification. Data were subjected to the non-parametric Kruskal-Wallis analysis of variance and Mann-Whitney test (p<0.05). Data were expressed as median leakage scores and mean ranks. RESULTS: All of the restorative systems had microleakage, regardless of the insertion technique and mechanical load cycling. Incremental placement significantly reduced microleakage as compared to the bulk technique, regardless of the restorative system used. Load cycling significantly affected incrementally placed restorations, except for the Hermes system.     

Gingival seal of deep Class II direct and indirect composite restorations

PURPOSE: To evaluate in vitro the gingival microleakage of Class II direct and indirect composite restorations with cervical margins 0.5 mm apical to the cemento-enamel junction (CEJ). METHODS: Mesial-occusal (MO) preparations of similar size were made in 10 homologous pairs of caries-free extracted human third molars. One specimen for each pair was prepared for a direct composite restoration and the other for an indirect composite restoration. Direct preparations were restored per manufacturer's instructions. Indirect preparations were impressed, and composite restorations were fabricated and cemented with a dual-cure cement. A total-etch technique was used for all restorations. Restorations were finished, polished, stored for 1 week in distilled water at 37 degrees C, thermocycled (5 degrees-55 degrees C x 1000), sealed with fingernail polish (leaving a 1.5 mm open periphery adjacent to the gingival margin), and placed in 0.5% basic fuchsin dye for 24 hours. Teeth were sectioned longitudinally (mesio-distally) within the restoration in two cuts and the four resulting surfaces (two inner cut surfaces, two outer cut surfaces) were evaluated for dye penetration with a x10 stereoscope using a scale of 0 (no penetration) to 4 (dye penetration involving more than half the axial wall). RESULTS: All 20 specimens had at least one score of three (dye penetration involving less than half of the axial wall) or four. Statistical analysis (Wilcoxon paired-sample test) disclosed a significant decrease in the indirect composite microleakage scores for the two outer cuts (P = 0.006, P = 0.002). No significant differences in microleakage scores were found between materials for the inner cut surfaces of the specimens. Overall, the results of die penetration showed no statistical difference between Class II direct and indirect composite restorations for microleakage.     

Microleakage of a single-bottle adhesive system with 3 restorative materials: in vitro study and clinical considerations

The purpose of this study is to evaluate whether differences in material composition between 3 restoratives (compomer, packable composite, and amalgam) affect microleakage in class II preparations. Class II cavity preparations were made in the mesial and distal surfaces of a noncarious human premolar with the gingival margins in dentin. Preparations were etched and rinsed, and a single-bottle adhesive agent (Prime & Bond NT) was applied. Preparations were restored with the following materials (n = 8 per group): Dyract AP, SureFil, and Dispersalloy. For Dyract AP total-bond restorations, a new nonrinse conditioner (NRC) was tested against a total-etch with 36% phosphoric acid. Specimens were coated with nail varnish, immersed in toluidine blue for 24 hours, and evaluated for dye penetration, after removal of the restorative material, using a 0-to-4 scale. Statistical analysis using analysis of variance revealed significantly higher leakage scores (P < .05) for the NRC-Dyract AP group when compared with all other groups. Dispersalloy had significantly lower scores compared with Dyract AP and SureFil, all with the total-etch bonding technique. No statistically significant difference was observed between the latter 2 groups. The inability of all 3 materials to create a perfect seal in vitro raises concerns about the ability of the adhesive system to provide completely sealed restorations in vivo. However, bonded amalgam restorations are more effective in reducing marginal microleakage, particularly at the dentinal margin.     

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.     

The effect of current-generation bonding systems on microleakage of resin composite restorations.

OBJECTIVE: The aim of this study was to determine the microleakage of current-generation dentin bonding systems in Class II resin composite restorations. METHOD AND MATERIALS: Class II (occlusodistal or occlusomesial) cavity preparations with a gingival margin 2 mm apical to the cementoenamel junction were prepared on 70 noncarious, extracted human premolar teeth. Teeth were randomly divided into five groups and treated with different-generation bonding systems (Optibond FL, Gluma One Bond, Clearfil SE Bond, acid etching plus Clearfil SE Bond, and Prompt-L-Pop). All cavities were restored in a posterior resin composite and subjected to 200 thermocycles (at 5 degrees C to 55 degrees C; 30-second dwell time). After immersion in 0.5% basic fuchsin dye for 24 hours, the teeth were sectioned longitudinally and evaluated for dye penetration using a binocular stereomicroscope. RESULTS: There was no statistically significant differences among bonding systems in the degree of microleakage in the occlusal walls. For gingival walls, statistically significant differences were found only between the Clearfil SE Bond and Prompt-L-Pop groups and the Clearfil SE Bond with acid etching and Prompt-L-Pop groups. The greatest microleakage was observed in Prompt-L-Pop specimens. CONCLUSION: Most of the tested dentin bonding systems were able to eliminate microleakage completely in the occlusal walls, but some systems exhibited statistically significant differences in leakage in the gingival walls.     

Effect of LED curing modes on the microleakage of a pit and fissure sealant

PURPOSE: To evaluate in vitro the curing effect of a very high intensity light-emitting diode (LED) unit and a conventional LED unit (including "soft-start" modes) on the microleakage of a pit and fissure sealant. METHODS: 120 intact caries-free human molars were randomly divided into six groups (n=20), sealed with Fissurit-F and polymerized using either a conventional halogen unit (Optilux) (Control group) in standard mode (40 seconds @ 600 mW/cm2); a very high intensity LED unit (Mini LED) in fast (10 seconds @ 1,100 mW/cm2) or soft-start mode (pulse mode: ten 1-second flashes @ 1,100 mW/cm2; exponential mode: exponential increase from 0 to 1,100 mW/cm2 within 10 seconds followed by 10 seconds @1,100 mW/cm2); or a conventional LED unit (Elipar Freelight) in standard (40 seconds @ 400 mW/cm2) or exponential mode (exponential increase from 0 to 400mW/cm2 within 12 seconds followed by 28 seconds @ 400 mW/cm2). Restored specimens were stored in distilled water at 37 degrees C for 24 hours. Specimens were then immersed in a 0.5% fuchsin dye solution for 24 hours, with half of the specimens from each group subjected to thermocycling (5/55 degrees C; x 1000) prior to dye immersion. After removal from the dye solution, specimens were sectioned and the degree of dye penetration scored. Data was statistically analyzed using the Kruskal-Wallis H test and the Mann-Whitney U-test (P< 0.05). RESULTS: There was no statistically significant difference in microleakage of pit and fissure sealant polymerized using various curing techniques. Thermocycling regimens had no effect on either LED- or halogen-cured specimens.     

Microleakage of Class II silver glass ionomer/composite restorations

This in vitro study examined the marginal integrity of Class II lesions using three restorative techniques. Class II preparations (MO and DO) were placed in 30 teeth. Half had the cervical margin placed 1 mm below the CEJ, the remaining had cervical margins 2 mm above the CEJ. The preparations were randomly restored using three techniques: 1) Glass ionomer liner and posterior composite resin; 2) Glass ionomer silver cermet placed in the proximal box to the contact area and the remainder restored with posterior composite resin; 3) Glass ionomer silver cermet only. All 30 teeth were loaded with 17 kg, thermocycled and stored in 37 degrees C solution for 30 days. The teeth were again loaded, immersed in 2% basic fuchsin solution for 24 hours, sectioned and photographed. Microleakage was calculated, according to the depth of dye penetration. Results demonstrated Techniques 1 and 2 to have less marginal leakage than Technique 3 when preparations remained in enamel and Techniques 1, 2 and 3 when preparations were below the CEJ. The chi-square test indicated a statistically significant difference between restoration technique and marginal microleakage (P less than 0.001).     

In vitro marginal leakage of cervical composite restorations lined with a light-cured glass ionomer.

The purpose of this research effort was to investigate the microleakage of cervical restorations lined with a light-cured glass-ionomer liner. Wedge-shaped cervical cavities were cut on extracted teeth with the gingival cavosurface margin involving dentin. The cavities were randomly assigned to each of each of three groups: (1) restored with a microfilled composite resin, (2) restored with a light-cured glass-ionomer liner and microfilled resin as in the "sandwich" technique, and (3) restored entirely with the light-cured glass-ionomer liner. Half of the specimens in each group were thermocycled. Microleakage of these restorations was assessed by dye penetration. The results showed that differences were more pronounced at the gingival margin. Composite restorations inserted over the glass-ionomer liner demonstrated significantly less leakage than when the liner was not used.     

Comparison of microleakage of experimental and selected commercially available bonding system

The microleakages of composite restorations bonded with two commercial and two experimental systems were observed. A high-viscosity condensable composite and a low-viscosity composite were used as the restorative materials. The bonding systems used were two widely accepted commercial brands and two experimental systems, one containing ferric oxalate and the other aluminum oxalate. Restorations were placed in cavities prepared in extracted human teeth and treated with the various bonding systems. These restorations were stored in 37 degrees C water for 24 hours and then polished. The restored teeth were subjected to seven days of thermocycling (5 degrees C-55 degrees C for 540 cycles per day). Microleakage was detected and scored from 0-4 according to the degree of stain penetration. The experimental systems had lower scores than the commercial systems. The high-viscosity composite restorations had microleakage scores higher than those of the lower-viscosity composite restorations.     

Effect of pre-heating resin composite on restoration microleakage

Improving the adaptation of resin composites during placement is necessary to increase durability and reduce microleakage. Flowable resin liners have been introduced to improve adaptation in composite restorations. In addition, a device that lowers the viscosity of regular dental composites has been introduced (Calset, AdDent Inc, Danbury, CT, USA). This device lowers the viscosity of composites by preheating them to 54.4 degrees C, which should lead to improved adaptation. This study compared microleakage in Class II composite restorations prepared using: 1) preheated resin composite, 2) unheated composite and 3) a flowable liner followed by unheated composite. Class II cavities were prepared on the mesial and distal surfaces of extracted third molars. Ten preparations were restored with resin composite (Esthet-X, Dentsply, York, PA, USA) for each of the following four techniques: Control (Esthet-X with Prime & Bond NT, Dentsply), Flowable (f) (as Control but used Esthet-X Flow liner), Preheated (p) (as Control but with preheating composite to 54.4 degrees C) and Delay (d) (as Preheated but followed by a 15-second delay before curing). The teeth were restored, finished, stored in distilled water for 24 hours, then thermocycled between water bath temperatures of 5 degrees C and 55 degrees C with a one-minute dwell time for 1000 cycles. Tooth apices were sealed with epoxy and varnish was applied to within 1 mm of the restoration margins. The teeth were placed in 0.5% basic fuschin dye for 24 hours, rinsed, then embedded in self-curing resin. The embedded teeth were sectioned mesiodistally with a slow-speed diamond saw, providing multiple sections per restoration. Microleakage was rated by two evaluators using a 0-4 ordinal scale at the occlusal and cervical margins of each restoration and light microscopy (40x). The data were analyzed with Kruskal-Wallis ANOVA and pairwise testing with the Sign test (alpha=0.05). No statistical differences were observed among materials at the occlusal margin. However, at the cervical margin, the preheated samples P showed statistically lower microleakage than the controls and all other treatments. The D samples showed higher microleakage than the P and F samples. Ranked sum scores for the cervical were D (4516), C (3974), F (2756) and P (1958). There was a statistically greater amount of leakage at the cervical margins compared to the occlusal p<0.05. Preheating the composite resulted in significantly less microleakage at the cervical margins compared to the flowable liner and control. Delaying light curing of the preheated composite for 15 seconds (D) was counterproductive and led to increased microleakage.     

Microleakage of cervical cavities restored with flowable composites

PURPOSE: To investigate the microleakage of cervical cavities restored with flowable composites in conjunction with an all-in-one adhesive system (AQ Bond) and an experimental two-step self-etching primer system (ABF) after thermocycling or flexural load cycling. METHODS: 180 wedge-shaped cervical cavities on the labial surfaces of bovine incisors were treated with AQ Bond or ABF according to the manufacturers' instructions. The treated cavities were filled with one of three flowable composites (AElite Flo, Metafil Flo or Protect Liner F). Ten of 30 specimens for each group were immersed in 0.5% basic fuchsin solution immediately after finishing of the restorations. Specimens to be subjected to thermocycling (5-60 degrees C, 15 seconds dwell time, 5000 cycles) or to flexural load cycling (approximately 0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 Hz) prior to immersion in the dye were also prepared. After 24-hour storage in the dye solution, the teeth were sectioned longitudinally through the center of the restorations, and the degrees of dye penetration scored. The microleakage scores of a hybrid composite (Clearfil AP-X) obtained from our previous study were used for comparison. The data were analyzed with the Kruskal-Wallis test and the Mann-Whitney U-test (P < 0.05). RESULTS: No significant differences in the microleakage patterns and scores were found among the flowable composites. On the other hand, significant differences in the microleakage patterns and scores were observed between the flowable and the hybrid composites. Thermocycling caused deterioration of marginal integrity, and the flowable composites showed more microleakage than the hybrid composite. In contrast, flexural load cycling did not cause deterioration of the marginal integrity when the cavities were filled with the flowable composites. Statistical analysis also revealed that the adhesive systems played a large role in the microleakage patterns.     

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).     

The effect of fiber placement or flowable resin lining on microleakage in Class II adhesive restorations

PURPOSE: The aim of this in vitro study was to evaluate the effect of two fibers (polyethylene or glass) and a flowable resin liner on microleakage in Class II adhesive restorations. MATERIALS AND METHODS: Class II adhesive cavities were prepared on mesial and distal surfaces of 40 extracted sound human molars. The cavity margins were below or above the CEJ. The teeth were randomly divided into four groups according to the restoration technique: group 1: restored with a resin composite (AP-X, Kuraray) in bulk after SE Bond (Kuraray) treatment; group 2: flowable resin liner (Protect Liner F, Kuraray) was used before composite restoration; in group 3, a polyethylene fiber (Ribbond) and in group 4, a glass fiber (everStick NET, StickTech) was placed into the bed of flowable resin before composite restoration. Samples were finished, stored in distilled water for 7 days at room temperature, and then thermocycled for 300 cycles between 5 degrees C and 55 degrees C. After sealing the apices, the teeth were varnished within 1 mm of the margins and placed in 0.5% basic fuchsin dye for 24 h at 37 degrees C. After rinsing, the teeth were sectioned longitudinally through the restorations and microleakage was evaluated with a stereomicroscope. Marginal penetration was scored on a 0 to 4 scale, and the data were statistically analyzed using Kruskal-Wallis and the Mann-Whitney U-test. RESULTS: Flowable resin, everStick NET, and Ribbond THM used in combination with flowable resin significantly reduced leakage at occlusal margins in cavities with enamel margins (p < 0.05). When the leakage values on cervical dentin margins were evaluated, there was no statistically significant difference among the tested groups (p > 0.05). CONCLUSION: Use of flowable composite alone or in combination with polyethylene or glass fibers reduces occlusal leakage in Class II adhesive cavities with enamel margins.     

Effects of flowable composite lining and operator experience on microleakage and internal voids in class II composite restorations

STATEMENT OF PROBLEM: When inexperienced clinicians perform class II composite restorations, improper placement techniques can lead to problems, including marginal adaptation and void formation. PURPOSE: The aim of this study was to determine the influence of flowable composite linings on marginal microleakage and internal voids in class II composite restorations performed by practitioners with different levels of experience. MATERIAL AND METHODS: Eighty extracted molars were prepared with mesial and distal class II cavity preparations and divided into 4 groups. Each group was restored separately with the following materials: Prodigy/Revolution lining (group I), Prodigy (group II), Tetric Ceram/Tetric Flow lining (group III), and Tetric Ceram (group IV). Each group was equally divided and restored by 2 practitioners, one experienced and another untrained in composite restorations. After restoration, all teeth were stored for 24 hours, thermocycled (at 5 degrees C to 60 degrees C) 1500 times, and soaked in 2% basic Fuchsin dye for 24 hours. After soaking, the teeth were sectioned, and 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 Kruskal-Wallis test. RESULTS: There was no significant reduction in microleakage for either practitioner. There were fewer interface voids within pairs with or without flowable composite linings made by the experienced practitioner (P<.05). CONCLUSION: When flowable composite lining was placed at the gingival floor of a class II composite restoration by an experienced practitioner, voids in the restored interface were reduced. Gingival marginal sealing was not improved by the same technique.     

Microleakage of different resin composite types.

OBJECTIVE: The purpose of this study was to evaluate the microleakage of Class V cavity preparations restored with three different types of resin composite and an ormocer. METHOD AND MATERIALS: Forty Class V cavities were prepared in buccal and lingual surfaces of 20 recently extracted molar teeth. The occlusal margin of each restoration was on enamel and the gingival margin on dentin. Teeth were randomly assigned to four groups of 5 teeth each and restored as follows: Group I, flowable resin composite (Tetric Flow); Group II, hybrid resin composite (Z100); Group III, packable resin composite (Solitaire 2); Group IV, organically modified ceramics-ormocer (Admira). In all groups, the manufacturers' instructions were strictly followed. All restorative resin composite materials were placed in one increment. All teeth were then immersed in 0.5% basic fuchsin solution for 24 hours after thermocycling (200 cycles; between 4 degrees C to 60 degrees C). The teeth then were longitudinally sectioned and observed under a stereomicroscope. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney tests. RESULTS: No statistically significant differences in microleakage were observed between groups either on enamel or dentin. CONCLUSION: All restorative materials demonstrated equal effectiveness in reducing microleakage.     

Microleakage of bonded amalgam restorations: effect of thermal cycling

This study examined the effect of thermal cycling on the microleakage of bonded amalgam restorations. Three dental amalgam alloys and a gallium alloy were tested with two adhesive resin systems and copal varnish as a control. Class V cavity preparations were prepared on 168 freshly extracted premolars or molars. The preparations were placed parallel to and 1.0 mm occlusal to the cementoenamel junction (CEJ). Four groups of 42 teeth each were treated with one of the following adhesive dentin systems: Bond-It, All-Bond 2/Resinomer or a copal varnish (Copalite). The four groups of 42 teeth each were then restored with one of three dental amalgams: Orosphere Plus, Indiloy, Oralloy or a Gallium alloy (Galloy), resulting in 12 test groups of 14 teeth each. The specimens were stored in double distilled water at 37 degrees C for 24 hours. Final contouring and polishing of the restorations were performed under water spray. Half of the restorations in each group were thermocycled for 3000 cycles (5 degrees C-37 degrees C-55 degrees C-37 degrees C) with a dwell time of 15 sec at each temperature. The other half were stored in double distilled water at 37 degrees C for 24 hours. Then all 168 restorations were stained with dye, sectioned and scored for microleakage. Results showed that the adhesive dentin systems reduced microleakage in amalgam restorations compared to copal varnish only in non-thermocycled specimens. Statistical analysis of the results showed that there was an extremely significant difference (p < 0.001) in microleakage between the non-thermocycled and the thermocycled specimens in all test groups, whereas, there was no significant difference (p > 0.05) among thermocycled specimens. The reduction of microleakage was not significantly different between Bond-It and All-Bond 2/Resinomer in non-thermocycled specimens. Oralloy showed the most microleakage in the non-thermocycled groups when compared to the other alloys using the same adhesive liner.