Influence of ZOE temporary restorations on microleakage in composite restorations

This study investigated the influence of zinc-oxide eugenol (ZOE) temporary restorations on microleakage in composite restorations. Class V cavities were prepared on the buccal surfaces of 32 freshly extracted, non-carious human premolars. The teeth were randomly divided into four groups of eight teeth. Specimens in Group 1 (control) received no temporary restoration. Group 2 and 3 specimens were covered with IRM (Type III ZOE cement) mixed at powder:liquid (P:L) ratio of 10g:1g and 10g:2g, respectively. Specimens in Group 4 were covered with poly-carboxylate cement (eugenol-free) mixed at a P:L ratio of 2.85g:1g. The temporary restorations were removed mechanically with an ultrasonic scaler after one week storage in distilled water at 37 degrees C. The preparations were washed and restored with Scotchbond Multi-Purpose Plus and Z100 according to manufacturers' instructions. The restorations were finished, thermally stressed for 400 cycles and subjected to dye penetration testing. Results were analyzed using Kruskal-Wallis and Mann-Whitney tests at a significance level of 0.05. At both enamel and dentin margins, the microleakage associated with Group 3 was significantly greater than for Groups 1, 2 and 4. For Groups 1 and 4, leakage at the dentin margins was significantly greater than in enamel margins. For the groups pretreated with IRM, no significant difference in dye penetration scores was observed between enamel and dentin. Pre-treatment with IRM mixed at a P:L ratio of 10g:2g significantly increased microleakage and is not recommended clinically.     

Adaptation and microleakage of composite resin restorations

A bstract — The ability of composite resins to adapt to acid-etched enamel cavity walls is examined and microleakage which occurs around composite resin restorations placed in etched and unetched cavities is investigated.
The use of an unfilled resin layer prior to application of the composite resin optimized adaptation. Cavity walls for composite resin restorations should be etched. For the teeth investigated, a 2 minute etch produced a more reliable etch pattern on the enamel and less micro-leakage than a 1 minute etch.     

Reduction of microleakage around new amalgam restorations

Microleakage is a problem of all fresh amalgam restorations and is clinically undetectable. Because microleakage may be responsible for pulp irritation, pulp inflammation, necrosis, and recurrent caries, it is essential to prevent and control it. Correct cavity margin preparations, proper amalgam manipulation, proper condensation, and burnishing can minimize microleakage in amalgam restorations. The use of conventional varnish or dentin adhesive on cavity walls before the insertion of the amalgam is the best method to reduce microleakage. Most well-manipulated and well-placed amalgams do not exhibit microleakage after a time.     

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.     

A diffusion model for microleakage in dental restorations

Microleakage is a significant problem in restorative dentistry. A model based on the principle of diffusion was developed to quantify the process of microleakage. The model required a certain quantity of radiotracer to be placed in the cavity and allowed to diffuse through the microgap that existed around the restoration. The rate of the tracer accumulation outside the restoration was found to follow a general relation of C(t)=C_∞ [1-exp(?bt)], when no dimensional change of the restoration was anticipated. “b” was a composite variable of the physical parameters of the restoration and equalled DA/LV₀. If the dimensional change was proportional to tⁿ then the relation would become C(t)=C_∞ [1-exp(?b′tⁿ⁺¹)], where b′=D₀A/[LV₀(n+1)]. The data generated from Finite Element Model simulation of either condition were shown to follow each respective model perfectly. The values of b, b′ and (n+1), which could be determined by a nonlinear regression of experimental data with respect to an appropriate relation, could be used to quantitatively describe the process of microleakage.     

Reinforced matrices for pin-amalgam restorations reduce microleakage

The considerable decrease in microkeakage in the compound-reinforced restorations may be due to the tighter fit of the matrix band at the gingival wall of the preparation, which allows better condensation and marginal sealing of the restoration. The compound prevents lateral migration of the band during condensation pressures.     

Early marginal microleakage in class II resin composite restorations

The aim of this study was to evaluate in vitro the early marginal microleakage around conventional and sandwich Class II (MOD) restorations. Ten different combinations of dentin bonding agents, glass-ionomer cements, and posterior resin composites were used. Class II cavities were prepared in freshly extracted third molars whose root surfaces had previously been coated. All gingival margins were prepared at the cementum-enamel junction. Teeth were filled by use of a multi-incremental technique, finished with discs, and immediately immersed in 2% erythrosin B for 12 h at 37 degrees C. Three transverse sections were made at 0.5 mm, 2 mm, and 3.5 mm over the cementum-enamel margin and evaluated under a stereomicroscope. Microleakage was scored linearly along the dentin/enamel-restoration interface. Sections at the cementum-enamel level showed significantly higher microleakage than the other two. Significant differences were observed between the various combinations of materials. Early marginal microleakage in Class II restorations depends not only on filling technique and on dentin bonding systems but also on the resin composite. Glass-ionomer cements significantly reduce early marginal microleakage in Class II restorations.     

Cervical microleakage in composite restorations of primary teeth--in vitro study

OBJECTIVE: The purpose of this study is to evaluate in vitro the cervical microleakage of two bonding systems (Group 1: Scotchbond Multi-Purpose-3M; Group 2: Clearfil Mega Bond-Kuraray) in occluso-proximal composite restorations of primary molars. METHODS: Two occluso-proximal standard cavities preparations (vertical slots) were made in each one of the 11 primary molars. The cavities were filled using adhesive systems (one for each cavity) and hybrid composite (Filtek Z250-3M) by incremental technique. The first increment was inserted horizontally at the cervical wall and light-cured with 100 mW/cm2 intensity for 60 s (VIP-Bisco). Other two increments were inserted diagonally on the buccal and lingual portion and each one light-cured with 200 mW/cm2 intensity for 60s. The restorations were finished and polished, and then partially sealed and embedded in 0.5% methylene blue solution for 24 h. The specimens were sectioned mesio-distally and the dye penetration was evaluated (score from 0 to 3) under a stereomicroscope. RESULTS: The statistical analysis (Qui square and Mann-Whitney non-parametric test) revealed no statistical difference (p=0.193) between the two adhesive systems tested. CONCLUSIONS: Both bonding systems provided small early cervical microleakage in occluso-proximal restorations of primary molars.     

Effect of endodontic irrigants on microleakage of coronal restorations

PURPOSE: To evaluate the effect of endodontic irrigants on the sealing ability of resin composite coronal restorations bonded with two different bonding systems, Clearfil SE Bond and PQ1. METHODS: The specially designed coronal preparations with distal margins on dentin and mesial margins on enamel were performed on 100 single-rooted teeth. They were initially divided into five groups. Irrigants used during the root canal preparation in each group were as follows: sodium hypochlorite, hydrogen peroxide, Tubulicid Plus, Cetrexidin and saline (control). After root canal filling, each irrigation group was divided into two bonding groups. Following the placement of the composite restorations, the specimens were immersed in India ink and cleared to allow visualization of the leakage. RESULTS: The differences among the irrigation groups were statistically significant only at margins remaining on dentin structures for both of the bonding resins (P< 0.05). Sodium hypochlorite, hydrogen peroxide groups demonstrated higher leakage scores than the controls (P< 0.005). Leakage patterns of Cetrexidin and Tubulicid Plus groups did not differ significantly from the controls (P> 0.005). Cetrexidin allowed better sealing than Tubulicid Plus in PQ1 bonded restorations, but did not in Clearfil SE Bond samples.     

Marginal quality and microleakage of adhesive class V restorations

OBJECTIVES: The aim of this in vitro study was to determine the marginal quality and microleakage of composite resin class V restorations. METHODS: Standardized mixed class V cavities (diameter: 4mm, depth: 2mm) with half of the finish lines limited within dentin were cut in 90 freshly extracted human molars and randomly assigned to nine groups (n=10). After etching enamel and dentin, the cavities were restored with nine different restorative systems (Syntac Sprint/Tetric Ceram=SS, Syntac Single-Component/Tetric Ceram=SC, Onestep/Aeliteflo=OS, Aquaprep+Onestep/Aeliteflo=OA, Prime & Bond 2.1/TPH=PB, Optibond Solo/Prodigy=OP, Singlebond/Z100=SB, Tenure Quik/Marathon=TQ, Solobond M/Arabesk=SM) using a wet-bonding procedure. After finishing and polishing, the teeth were stored for 24h in distilled water at 37 degrees C before they were subjected to thermocycling (5/55 degrees C, 1000x). Epoxy replicas were made for margin analysis in the SEM. Specimens were stained in methylene blue, sectioned, and evaluated for microleakage. Dye penetration was scored on a 0-3 ordinal scale. RESULTS: Statistical analysis (Kruskal-Wallis H-test, Mann-Whitney U-test) revealed significant differences (P<0.05) among the groups at dentin and enamel margins for the microleakage scores as well as for the results of the quantitative SEM margin analysis. SC revealed a significantly higher percentage of perfect margins in the SEM than OS and SM in enamel and dentin, respectively. OA exhibited significantly more leakage in enamel than all other groups. CONCLUSIONS: None of the tested restorative systems achieved a perfect seal in dentin and enamel of mixed class V cavities. Marginal quality and sealing ability of adhesive systems to dentin, using a wet-bonding procedure, is still inferior compared with enamel margins.     

纤维桩修复的冠向微渗漏研究概况

随着口腔材料学的发展,纤维桩得以面世并迅速推广。纤维桩的美学性能优良,大多数体外实验表明其物理和机械性能均能满足临床使用的要求,且更有利于保存牙体组织,但目前有关纤维桩的长期临床报道较少。冠向微渗漏是导致桩核修复失败的常见原因,与纤维桩修复的长期临床效果有密切联系。本文就纤维桩修复的冠向微渗漏研究概况作一综述。     

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.     

Evaluation of microleakage of composite resin restorations by an electrochemical technique: the impedance methodology.

OBJECTIVES: The aim of our in vitro study was to quantitatively evaluate dentin microleakage by means of the impedance technique. METHODS: Forty-five 2 mm thick dentin disks were embedded in a hollow polyurethane resin cylinder. The system used was a 'like' permeation cell. Standard cylindrical cavities (1.5 mm deep, 3.5 mm diameter) were prepared on the occlusal side of the disk. The current passing through the dentin was measured to calculate impedance and to establish resistance of the sample. The doses were then randomly divided into nine groups (n = 5). Each group was bounded with a different adhesive system and filled with microhybrid composite resin (Filtek P60). The initial measurement with the empty cavity and the record measurement (t = 0) were performed to evaluate initial resistance after filling. Samples were then thermocycled. RESULTS: At t = 0, the highest value was obtained with EP (550%), the lowest with PLP (115%). The values of other adhesives ranged in a group (350-450%) without statistical difference. After thermocycling, all groups exhibited no significant difference (350-230%) except PLP (50%). The lower joint degradation rate (5%) was obtained with OS with a significant difference for all systems, the higher with PLP (35%). The results for other adhesives ranged from 20 to 27% without significant difference. SIGNIFICANCE: Dentin microleakage may be quantified with the impedance technique and this has shown that, except for PLP, the differences between the two families of adhesives are slight. This methodology is able to prove the influence of thermocycling in terms of joint degradation.     

The effects on pulp tissue of microleakage in resin composite restorations

The purpose of this study was to evaluate histopathologically the effect on pulp tissue of microleakage in resin composite restorations. Seventy-two class V cavities were prepared on buccal surfaces of monkeys and divided into 3 groups, F, O, and S. Every cavity was etched with 37% phosphoric acid. In group F cavities, each cavity was restored with photo-curable composite without any dentin adhesives. In group O, the cavities were left unfilled. In group S, each cavity was treated with a dentin adhesive system and restored with a restorative composite. After 3, 30, or 90 days, animals were sacrificed and the subjected teeth were immediately removed, then fixed and decalcified. Following sectioning and staining with hematoxylin and eosin or Taylor's modified bacteria staining, each sample was examined with a light microscope. In most teeth with group S cavities, bacterial invasion was not found indicating excellent marginal sealing. The pulpal reaction was much less than that in other groups. In group F as well as in group O, bacteria were frequently observed in the cavity; however, bacteria penetrated into dentinal tubules more in group F than in group O at 30 and 90 days. A correlation between the presence of bacteria and pulpal inflammation was strongly indicated. It was suggested that a leaky restoration was more harmful to the pulp than an open prepared cavity without restoration.     

In vitro microleakage of packable composites in Class II restorations.

OBJECTIVES: To evaluate the microleakage in Class II resin restorations at different margins and the polymerization shrinkage of the composites used. METHOD AND MATERIALS: Four standardized Class II (3 x 5 x 2 mm) cavities were prepared in 32 teeth. The sample had the gingival margin either 1 mm below or above the cementoenamel junction. Teeth were divided and restored according to the following protocols: (1) Single Bond + P60; (2) Prime & Bond NT + Surefil; (3) Bond-1 + Alert; and (4) Prime & Bond 2.1 + TPH. After 7 days, the specimens were thermocycled (500 cycles between 5 to 55 degrees C with a 15-second dwell time), immersed in 0.5% methylene blue for 24 hours, sectioned, and evaluated (both surfaces) at the gingival margin by two examiners, using a 0 to 3 marginal infiltration score system. The polymerization shrinkage of the composites (n = 6) was evaluated by the disk deflective method. Microleakage data was evaluated by nonparametric repeated measures ANOVA. The percentage of polymerization shrinkage was evaluated by ANOVA and Tukey's test. RESULTS: Only protocol 3 showed a significant difference between enamel and cementum margin. No difference was detected among the protocols in the enamel margin. Only protocol 1 provided a good seal in the cementum margin. All packable composites showed lower polymerization shrinkage than the hybrid tested. CONCLUSION: All protocols are able to prevent dye penetration in enamel margins; however, protocol 1 is preferable to reduce the microleakage in the cementum margin. The packable composites showed lower polymerization shrinkage compared to the hybrid resin.     

Reducing microleakage in composite resin restorations: an in vitro study

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