Microleakage of resin-modified glass ionomer cement restorations: an in vitro study

Influence of occlusal and proximal caries on the outcome of full pulpotomy in permanent mandibular molar teeth with partial irreversible pulpitis: A prospective study

AIM

To assess the influence of occlusal and proximal deep carious lesions on the outcome of full pulpotomy performed in mandibular teeth with pulpal diagnosis of symptomatic partial irreversible pulpitis.

METHODOLOGY

Eighty deep carious mandibular molar teeth with clinical and radiographic diagnosis of symptomatic partial irreversible pulpitis without periapical rarefaction from patients of either gender between the age of 16-35 years were included. Depending upon the location of deep carious lesion, the teeth were distributed equally into occlusal (n = 40) and proximal caries groups (n = 40). Full pulpotomy was performed under local anaesthesia and aseptic conditions. The pulp tissue was removed until the root canal orifices, and 2.5% sodium hypochlorite (NaOCl) was applied to arrest pulpal bleeding. Mineral trioxide aggregate (MTA) was compacted over the radicular pulp. Teeth were restored with resin-modified glass ionomer cement (RMGIC) and bulk-fill composite resin. Pre- and post-operative pain was assessed at 24, 48 and 72 h using a 11-point Numerical Rating Scale (NRS). Patients were followed at 6 and 12 months for clinical and radiographic evaluation. Asymptomatic teeth without any radiographic evidence of periapical rarefaction were considered successful. The data were analysed using the Shapiro-Wilk W test, two-sample Wilcoxon rank-sum test, Pearson chi-square test, Fisher's exact test and Kappa coefficient. The significance level was predetermined at p < .05.

RESULT

An intergroup comparison revealed that the pre- and post-operative pain scores at 24, 48 and 72 h were not significantly different (p > .05). At the end of follow-up period (12 months), success of full pulpotomy in occlusal and proximal caries group was 95% and 92.5%, respectively (p = .644). For both groups, the combined success rate of full pulpotomy was 93.75%.

CONCLUSION

The site of carious lesions (i.e., occlusal or proximal) did not affect the clinical and radiographic outcome of full pulpotomy performed in mature permanent mandibular teeth with symptomatic partial irreversible pulpitis.

Evaluation of sealing ability two self-etching adhesive systems and a glass ionomer lining LC under composite restoration in primary tooth: An in vitro study

Aims and Objectives:

To evaluate the sealing ability of two self-etching adhesive systems and glass ionomer cement (GIC) lining Light cure (LC) under composite restorations in primary teeth.

Materials and Methods:

Class V cavities are prepared on the cervical third of the facial and lingual surfaces of primary molars. The specimens are then assigned into four experimental groups. The restored primary molars are stored in distilled water and subjected to thermocycling. Each section was examined using a stereomicroscope to assess dye penetration at the margin of the restoration and evaluated via pictures.

Statistical Analysis Used:

The degree of microleakage was analyzed using Kruskal–Wallis test and the intergroup significance by multiple comparison analysis.

Results:

The mean rank of the groups are Group I (Adper Prompt™ + Z−100) 19.44, Group II (UniFil BOND + Solare) 5.38, Group III (GIC lining LC + Z−100) 20.06, and Group IV (GIC lining LC + Solare) 21.13 with the P < 0.001.

Conclusion:

Composite resin restorations bonded with two-step self-etching adhesive system (UniFil Bond) exhibited lesser microleakage than one-step self-etching adhesive system (Adperprompt™) in primary teeth.

Experimental initial partial polymerization method for Fuji II placement evaluated for microleakage with/without Fuji Coat

PURPOSE

This laboratory study evaluated an experimental 1-second initial partial polymerization (IPP) technique using Fuji II LC vs the manufacturer's standard placement (control), both with and without Fuji Coat, relative to microleakage.

METHODS

Class V restorative preparations were placed on the buccal and lingual aspects of 30 permanent, caries-free and restoration-free, third molar teeth. Fuji II LC restorations were placed either following manufacturer-specified guidelines or IPP for 1 second prior to contouring and full light curing. Half of the restorations were placed using the IPP experimental technique and half of the teeth were finished using Fuji Coat LC. Following thermocycling, specimens were sectioned and dye penetration was measured. SPSS 16 was used for statistical analysis (p<0.05).

RESULTS

Mean microleakage results: experimental/varnish (0.08 ± 0.15 mm), control/varnish (0.17 ± 0.35 mm), experimental/nonvarnish (0.33 ± 0.33 mm), and control/nonvarnish (0.58 ± 0.47 mm). Univariate analysis of variance demonstrated significantly less microleakage for the experimental technique (p<0.001), use of finishing varnish (p<0.001), and the combination of experimental/varnish (p=0.013).

CONCLUSIONS

The initial partial polymerization technique of Fuji II LC placement significantly reduces microleakage. Fuji Coat LC results in further diminished microleakage.

Effect of acid etching of glass ionomer cement surface on the microleakage of sandwich restorations

The purposes of this study were to evaluate the sealing ability of different glass ionomer cements (GICs) used for sandwich restorations and to assess the effect of acid etching of GIC on microleakage at GIC-resin composite interface. Forty cavities were prepared on the proximal surfaces of 20 permanent human premolars (2 cavities per tooth), assigned to 4 groups (n=10) and restored as follows: Group CIE – conventional GIC (CI) was applied onto the axial and cervical cavity walls, allowed setting for 5 min and acid etched (E) along the cavity margins with 35% phosphoric acid for 15 s, washed for 30 s and water was blotted; the adhesive system was applied and light cured for 10 s, completing the restoration with composite resin light cured for 40 s; Group CIN – same as Group CIE, except for acid etching of the CI surface; Group RME – same as CIE, but using a resin modified GIC (RMGIC); Group RMN – same as Group RME, except for acid etching of the RMGIC surface. Specimens were soaked in 1% methylene blue dye solution at 24°C for 24 h, rinsed under running water for 1 h, bisected longitudinally and dye penetration was measured following the ISO/TS 11405-2003 standard. Results were statistically analyzed by Kruskal-Wallis and chi-square tests (α=0.05). Dye penetration scores were as follow: CIE – 2.5; CIN – 2.5; RME – 0.9; and RMN – 0.6. The results suggest that phosphoric acid etching of GIC prior to the placement of composite resin does not improve the sealing ability of sandwich restorations. The RMGIC was more effective in preventing dye penetration at the GIC-resin composite- dentin interfaces than CI.

The Influence of Time Interval between Bleaching and Enamel Bonding

OBJECTIVES

The purpose of this study was to investigate the penetration of a conventional adhesive material into enamel bleached with 16% carbamide peroxide and 38% hydrogen peroxide using optical light microscopy.

METHODS

Extracted human teeth were randomly divided into eight experimental groups with six specimens each, according to the bleaching material and time interval after bleaching and before the bonding procedure. Groups were designated as follows: control group, restorations in unbleached teeth; restorations performed immediately after bleaching; restorations performed 7 days after bleaching; restorations performed 14 days after bleaching; and restorations performed 30 days after bleaching. The length of resin tags was measured with an Axiophot photomicroscope at 400x magnification for the calculation of the proportion of tags of study groups compared to the respective control groups. Analysis of variance was applied for comparison between groups; data were transformed into arcsine (p < 0.05).

RESULTS

The specimens of experimental groups, in which restorations were performed 7, 14, and 30 days after bleaching, showed better penetration of adhesive material into enamel than specimens restored immediately after bleaching. There was no statistically significant difference between the bleaching materials employed or in the interaction between bleaching agent and time interval.

CONCLUSIONS

This suggests that a time interval of at least 7 days should be allowed between enamel bleaching and placement of adhesive bonding agents for accomplishment of composite resin restorations.

CLINICAL SIGNIFICANCE

Establishment of adequate time after bleaching is fundamental to allow the normal penetration of a one-bottle conventional adhesive onto the enamel surface.

Class II restorations: influence of a liner with rubbery qualities on the occurrence and size of cervical gaps

The aim of this study was to evaluate the ability of new rubbery liners, used as a cervical increment, to relieve contraction stress and thereby reduce the formation of cervical gaps in class II composite restorations. The investigated liners were made of polyester-acrylate (PE(1), PE(2) or PE(3)) or silicone-acrylate (S), mixed with UDMA, without (A, B, C, D) or with HEMA (AH, BH, CH, DH). A silanized filler was added to the mixture, DH, to give composites with 20, 40, 60, and 70% (w/w) of filler (DHF20, DHF40, DHF60, DHF70, respectively). The presence and width of cervical gaps were determined using a light microscope. Statistical analysis showed that six of the 12 rubbery liners (AH-DH, DHF20-DHF40) significantly decreased gap formation in comparison with the control group. In addition, the polymerization shrinkage, flow, and strain capacity of these liners were measured and the influence of these factors on gap formation was examined. Two- and three-dimensional regression analyses showed significantly negative linear correlations between gap formation and strain capacity, and between gap formation and flow, and a significantly positive linear correlation between gap formation and shrinkage.

Glass ionomer microleakage from preparations by an Er/YAG laser or a high-speed handpiece

OBJECTIVE

The purpose of this study was to compare microleakage of glass ionomer materials (GIC) using two different modes of cavity preparation: a high-speed hand piece and an erbium/yttrium-aluminum-garnet (Er/YAG) laser.

METHODS

Eighty caries free permanent molar teeth had class V preparations cut on both the buccal and lingual surfaces. The high-speed hand piece was used to prepare a class V cavity preparation on the buccal surface and an Er/YAG laser was used to prepare a class V cavity preparation on the lingual surface. GIC or resin modified GIC was used as the restorative material. The teeth were thermocycled for 7000 cycles, placed in 2% basic fushin for 24h, sectioned in the center of each restoration, and analyzed under a stereomicroscope.

RESULTS

There was no statistical difference in microleakage between the two modes of cavity preparations. The gingival margins had more microleakage than the occlusal margins for both GIC materials and the resin modified GIC showed significantly more leakage than the conventional GIC.

CONCLUSIONS

The Er/YAG laser provided an equivalent method of tooth removal when evaluated for microleakage of GIC materials compared to a high-speed hand piece.

[Assessment of microleakage of adhesive restorative materials in deciduous teeth]

The microleakage of Chelon-Fil, Vitremer, Compoglass-F and Z100 was evaluated in deciduous teeth. Class V restorations were placed in the buccal aspect of 40 extracted primary canines; they were thermocycled, and immersed in 0.5% basic fuchsin. Three slices of each tooth were obtained in order to analyze the penetration of dye in the gingival and occlusal walls, under magnification of 40 X. The results showed that Chelon-Fil had the highest degree of marginal leakage. Vitremer, Compoglass-F and Z100 presented similar penetration of dye. The microleakage of Chelon-Fil and Vitremer was greater in the gingival wall than in the occlusal wall. Microleakage was the same in both gingival and occlusal walls when cavities were filled, either with Z100 or with Compoglass-F.

Fluoride release, microbial inhibition and microleakage pattern of two orthodontic band cements

OBJECTIVES

To compare, in vitro, the fluoride release, microbial inhibition and microleakage pattern of a conventional glass ionomer cement (Ketac-Cem) and an acid-modified composite (Ultra Band-Lok) for band cementation.

METHODS

Fluoride release was measured from cement discs (3.0 mm diameter and 1.5 mm thick) at regular intervals over 40 days using a potentiometric method. Microbial inhibition was determined for each cement using an agar diffusion test against one of four different strains of Streptococcus mutans. Thirty pairs of banded third molars (15 banded pairs for each cement) were thermocycled and microleakage determined by a dye penetration method. The depth of microleakage was assessed by an index applied by two examiners independently to photographic records taken of the mid-buccal aspect of each tooth.

RESULTS

The cumulative and daily fluoride release for days 5, 15 and 40 were significantly greater for Ketac-Cem than for Ultra Band-Lok (all p < 0.05). After the initial set, the anti-microbial activity was significantly greater for Ketac-Cem than for Ultra Band-Lok over the following 24 h period for all four strains of S. mutans (all p < 0.05). There was no significant difference between the two cement groups for microleakage at the cement/enamel interface (p = 0.66) but a borderline significance was detected for microleakage at the cement/band interface (p = 0.051).

CONCLUSIONS

The fluoride release and anti-microbial activity of Ketac-Cem were greater than that of Ultra Band-Lok. There was no significant difference in microleakage between the cements at the cement/enamel interface but a borderline difference existed between the cements at the cement/band interface.

Microleakage of Class V resin-modified glass ionomer and compomer restorations

STATEMENT OF PROBLEM

Resin-modified glass ionomers and polyacid-modified resin composites (compomers) have been introduced to provide esthetic restorations. However, there is concern about the marginal sealing ability of these materials, especially at the dentin (cementum) aspects of restorations.

PURPOSE

This in vitro study evaluated the microleakage of Class V restorations made with resin-modified glass ionomers or a compomer.

MATERIAL AND METHODS

Thirty noncarious human molar teeth were used. Standardized kidney-shaped Class V cavity preparations were placed in the buccal and lingual surfaces at the cementoenamel junction. Teeth were randomly assigned to 3 experimental groups of 10 teeth each and restored as follows: group 1, Fuji II LC; group 2, Vitremer; and group 3, Dyract. In all cases, the manufacturers' instructions were strictly followed. All materials were placed in a single increment. Unfinished restorations were immediately coated with the respective manufacturers' sealer or varnish and this was either light cured for 20 seconds or allowed to air-dry. After 24 hours, teeth were finished to contour and to the cavosurface margins, coated with nail varnish except for 1 mm around the restoration margin, thermocycled (1000x, 5-55 degrees C) and placed in a solution of 2% basic fuchsin dye for 24 hours at room temperature. The staining along the tooth restoration interface was recorded.

RESULTS

Kruskal-Wallis 1-way analysis of variance revealed significant differences among all restorative materials for the overall, occlusal, and gingival scores (P =.03, P =.01, P =.01, respectively). Occlusal and gingival scores for each matched pair of restorative materials using the Wilcoxon test showed statistically significant differences between Fuji II LC glass ionomer cement and Dyract composite, both for the occlusal (P =.005) and gingival (P =.005) margins and also as an overall evaluation (P =.01), with Fuji II LC showing the least dye penetration. Vitremer revealed dye penetration scores not significantly different from Fuji II LC glass ionomer cement or Dyract composite.

CONCLUSION

Resin-modified glass ionomers showed less or similar microleakage than the polyacid-modified composite resin tested.

Resin-ionomer restorative materials for children: a review

Hybrid restorative materials comprising resins and components of conventional glass ionomers have been widely introduced and accepted by the dental profession in recent years. These include the resin-modified glass ionomer cements and the polyacidmodified resin composites or compomers. They are developed in an attempt to overcome the problems of traditional restoratives, such as moisture sensitivity and reduced early strength, while at the same time maintaining their clinical advantages of command setting, adhesion to tooth structures, adequate strength to occlusal load, fluoride release and aesthetics. This paper reviews the development, composition and properties of these new materials. Their clinical performance appears to be promising and they should be considered as good alternatives to amalgam and other conventional restorative materials in the future.

Interfacial characteristics of resin-modified glass-ionomer materials: a study on fluid permeability using confocal fluorescence microscopy

The tooth interface with resin-modified glass-ionomer cements (RM GICs) is poorly understood. This study examined the interface, especially with dentin. Cervical cavities in extracted teeth were restored with Fuji II LC, Vitremer, Photac-Fil, or a conventional GIC, Fuji Cap II. Fluorescent dye was placed in the pulp chambers for 3 hrs before the specimens were sectioned. Examination of the tooth/material interface with a confocal microscope showed that dye uptake by the restoration varied among materials. A "structureless", non-particulate, highly-stained layer of GIC was observed next to dentin in Fuji II LC. This layer varied in width, was prominent where the dentin tubules were cut "end-on" and in areas closer to the pulp, and was not seen adjacent to enamel. Vitremer showed minimal dye uptake, and the "structureless" layer was barely discernible. Photac-Fil showed more uniform uptake and absence of this layer. Cracking of enamel was also noted with these materials. The conventional GIC did not show any dye uptake, presence of a "structureless" layer, or enamel cracking. We elucidated the potential mechanisms involved in the formation of a "structureless" interfacial layer in Fuji II LC by studying the variables of cavity design, surface pre-treatment, water content of the tooth, time for it to develop, early finishing, and coating of the restoration. This layer, the "absorption layer", is probably related to water flux within the maturing cement, depending on environmental moisture changes and communication with the pulp in a wet tooth. The "micropermeability model" was useful in this study of the interfacial characteristics of RM GICs.

Long-term mechanical characteristics of resin-modified glass ionomer restorative materials

OBJECTIVES

The purpose of this study was to compare the effects of long-term water storage on the mechanical characteristics of four resin-modified glass ionomer restorative materials with those of a conventional glass ionomer cement and a resin composite material.

METHODS

Cylindrical specimens were prepared and stored in water for 1 h, 24 h, 1 wk, 1 mon, 3 mon and 6 mon prior to determination of diametral tensile strength (DTS) and depth of surface indentation both under 1 N load and after removal of the load.

RESULTS

Diametral tensile strength was lowest for the conventional glass ionomer cement and highest for the composite; the resin-modified glass ionomer cements were intermediate between the reference materials. Water storage reduced DTS between 24 h and 1 wk or 1 mon but then remained unaffected until the final measurements after 6 mon. The materials showed a trend toward a slight increase in the depth of indentation both under load and after removal of the load with increasing storage time. These mechanical properties indicate the position of four resin-modified glass ionomer cements on a continuum with conventional glass ionomer cement and resin composite as the end points.

SIGNIFICANCE

The mechanical properties of resin-modified glass ionomers show that this group of materials is weaker than resin composite but stronger than conventional glass ionomer cement. Water storage for 6 mon has little adverse effect on the mechanical properties.