Comparison of the Effect of Nd:YAG and Diode Lasers and Photodynamic Therapy on Microleakage of Class V Composite Resin Restorations

Effect of the Nd:YAG laser on the micro-tensile bond strength of composite resin to dentin with hypersensitivity using different universal adhesives

Background

This study aimed to evaluate the effect of the Nd: YAG laser on the tensile bond strength of composite resin to dentin with hypersensitivity using different universal bonding systems.

Material and Methods

After cutting the crown of 252 molars, buccal cervical enamel was removed at a thickness of approximately 2 mm, and 252 smooth dentin surfaces were exposed. Then they were etched with 0.5 M ethylenediaminetetraacetic acid (pH = 7.4) to stimulate hypersensitivity. The specimens were then randomly divided into 12 groups (n= 21) according to the surface treatments performed. After etching and bonding according to the manufacturer's recommendations in each group, the entire dentin surface was restored with Valux Plus composite resin. The samples were thermocycled and a universal test machine was used to measure the microtensile bond strength. The failure mode for each sample was observed under a stereomicroscope. For data analysis, the Bonferroni test, the independent t-test and the three-way anova test were used.

Results

The average microtensile bond strength in non-laser samples was higher than the average in laser samples (P<0.001). In comparison with the bonding agent type in both cases with and without laser, the highest average microtensile bond strength was related to ALL-BOND (P<0.001), meanwhile the lowest average tensile strength in samples without laser was related to G-Premio universal adhesive (P<0.001), and the lowest average microtensile strength in samples with laser belonged to Prime and Bond Elect group (P<0.001).

Conclusions

Nd: YAG laser irradiation of the dentin surface before applying the adhesive significantly decreased the microtensile bond strength of the composite resin to the dentin surface. Key words:Nd:YAG laser, Bond strength, Dentin, hypersensitivity, Universal adhesives.

Comparison the Effect of Bromelain Enzyme, Phosphoric Acid, and Polyacrylic Acid Treatment on Microleakage of Composite and Glass Ionomer Restorations

Statement of the Problem

Resin modified glass-ionomer cement (RMGIC) shows low microleakage values. Bromelain enzyme is a deproteinizing agent with an anti-inflammatory effect in human body.Efective cavity treatment is an important factor in reduction of microleakage.

Purpose

The aim of this study was to determine the effectiveness of the deproteinizing aspect of 10% bromelain enzyme on the microleakage of RMGIC and composite restorations.

Materials and Method

In this experimental study, 40 non-carious extracted human molar teeth were categorized in eight experimental groups (n=5). Standard class V cavities were prepared on the buccal and lingual surfaces of the teeth (n=10). The specimen were classified as Group 1, in which 20% polyacrylic acid (PAA) was applied on the teeth then treated with 10% bromelain enzyme; Group 2: 10% bromelain enzyme was applied; Group 3: 10% bromelain enzyme was applied and then treated with polyacrylic acid; Group 4: 20% polyacrylic acid was applied. Groups1 to 4 were restored with RMGIC (Fuji II LC, GC, Japan). Group 5: etched by 37% phosphoric acid and then treated by 10% bromelain; Group 6: 10% bromelain enzyme was applied without etching; Group 7: teeth were deproteinized with 10% bromelain enzyme and then etched with 37% phosphoric acid; and Group 8: cavities were etched with 37% phosphoric acid. In the groups 5 to 8, Adper single bond (3M, ESPE, USA) and filled with composite resin Z350 (3M, ESPE, USA). After thermocycling, the teeth were sectioned. Microleakage scores were measured using stereomicroscope (40×). Kruskal-Wallis and Mann-Whitney tests were used for data analysis. (p< 0.05).

Results

Statistical analysis did not show any significant difference in occlusal and gingival margin microleakage in glass ionomer groups (1-4) (occlusal p= 0.218, gingival p= 0.192). Kruskal-Wallis revealed significant difference in occlusal and gingival margin microleakage of Groups 5 to 8 (occlusal p= 0.006 and gingival p= 0.00). Group 5 demonstrated the lowest occlusal microleakage (occlusal mean=0.00).

Conclusion

Applying bromelain or polyacrylic acid did not affect the microleakage of glass ionomer filling. Due to the antinflamatory effects of bromelain, we suggest using it instead of PAA. Pretreatment of 10% bromelain enzyme after phosphoric acid significantly decreased microleakage in the occlusal and gingival margin of composite filling.

The effects of cavity disinfection on the nanoleakage of compomer restorations: an in vitro study

Purpose:

Cavity disinfection, in addition to routine caries removal methods, is recommended to eliminate the microorganisms. The aim of this study was to compare the effect of various systems Er,Cr:YSGG lasers, diode lasers and FotoSan and agents Corsodyl; Cervitec and Cervitec Plus and Fluor Protector—on the nanoleakage of compomer restorations when used for cavity disinfection.

Materials and methods:

A total of 40 intact human deciduous molar teeth containing Black V cavities (3×2×1.5 mm) on the buccal and lingual surfaces parallel to the cementoenamel junction were randomly divided into 8 groups according to the cavity disinfection methods. The antibacterial agents and systems were applied according to the manufacturer’s instructions. Restorations were completed using a compomer. The restored teeth were then subjected to thermocycling for 500 cycles in a water bath at 5°C and 55°C with a dwell time of 30 seconds. After the thermocycling procedures, 1-mm sticks were obtained from the center of each cavity to prepare for the nanoleakage test. After the teeth were sectioned, they were immersed in 50 wt % ammoniacal silver nitrate solution for 24 hours and dipped in photo-developing solutions for 8 hours with fluorescent light irradiation. The samples were examined under a scanning electron microscope (SEM). The non-parametric Kruskal-Wallis and Mann-Whitney U test (p<0.05) were applied.

Results:

The Er,Cr:YSGG laser group showed significantly less nanoleakage than all of the tested groups (p<0.01). The diode laser, Fluor protector and FotoSan groups showed similar nanoleakage to that of the control group (p>0.05). The Corsodyl (p<0.01) and Cervitec (p<0.001) groups showed significantly higher nanoleakage than the control group.

Conclusion:

Er,Cr:YSGG laser irradiation which showed lower nanoleakage scores from either control or tested groups can be recommended for cavity disinfection Additionally, a diode laser and FotoSan, which have antibacterial effects and no negative effect on leakage, can be used for cavity disinfection.

Effect of Diode Laser (810 nm) Irradiation on Marginal Microleakage of Multi-mode Adhesive Resins in Class V Composite Restorations

Introduction: Some studies have shown that laser irradiation on unpolymerized adhesives can improve composite-dentin adhesion. The aim of the present study was to evaluate the effect of the diode laser (810 nm) on the microleakage of multi-mode adhesive systems at enamel and dentin margins of composite restorations. Methods: Classic class V boxes were prepared on 48 sound premolar teeth and randomly divided into 6 groups (n=16). In the control groups, Scotchbond Universal (SBC), G-Premio (GBC), and Ambar U (AMC) were used by a self-etch mode. In the test groups (SBL, GBL, ABL), the 810 nm diode laser was irradiated (1 W) for 10 seconds before the polymerization of the adhesive. The boxes were restored by the resin composite. After finishing and polishing, the samples were thermocycled (5°C to 55°C) for 1000 cycles and then immersed in 0.1% methylene blue dye (48 hours). Dye penetration through the gingival and occlusal margins was measured by Stereomicroscope. The data were analyzed at the 5% significance level using Kruskal-Wallis and Mann-Whitney U tests. Results: Significant differences were found between the control and test groups (P < 0.05). The occlusal margins of the SBL and GBL groups and the cervical margin of the SBL group exhibited the lowest microleakage (P < 0.05). The AM control group showed maximum microleakage at cervical and occlusal margins. Conclusion: The irradiation of the 810 nm diode laser on the unpolymerized universal adhesive systems in a self-etch mode caused a significant reduction in enamel and dentin marginal microleakage of composite restorations.

Effect of various dentin disinfection protocols on the bond strength of resin modified glass ionomer restorative material

Background

Disinfection of dentin surface prior to any restorative therapy is important for the longevity of the treatment rendered. However, these dentin disinfection methods should itself not interfere with the adhesion of the restorative material. Therefore the aim of this study was to determine the effect of various dentin disinfection protocols on the shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC).

Material and Methods

The occlusal surface of 40 extracted premolars were trimmed to obtain a flat dentinal surface and was randomly divided into four groups. CTRL was the control group; NaOCl was 1% sodium hypochlorite disinfection group; CHX was 2% chlorhexidine disinfection group; and PAD was the photo-activated disinfection group. Then a predetermined dimension of RMGIC was bonded to the pre-treated dentin surfaces. Following this, each sample was tested for SBS using universal testing machine at a crosshead speed of 0.5mm/min.

Results

Among the test groups, CHX showed the least reduction in SBS and NaOCl the highest reduction in SBS as compared to the control group. PAD on the other hand showed significantly lower SBS than CTRL and CHX groups, but the values were higher than the NaOCl group.

Conclusions

Thus, it could be concluded from the present study that use of chlorhexidine based dentin disinfection does interfere with the adhesion of RMGIC. However, photo-activated disinfection should be done with caution. Moreover, sodium hypochlorite based disinfectants should be avoided prior to the use of RMGIC.

Key words:Chlorhexidine, Dentin disinfection, Photo-activated disinfection, Resin modified glass ionomer cement, Shear bond strength, Sodium hypochlorite.

Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

BACKGROUND

The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching.

MATERIAL AND METHODS

The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05).

RESULTS

A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching.

CONCLUSIONS

The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material.

KEY WORDS

Laser, diode, dentin, tubule, diameter.

An in vitro Evaluation of Microleakage of Posterior Teeth Restored with Amalgam, Composite and Zirconomer - A Stereomicroscopic Study

BACKGROUND

Numerous restorative materials are being used in dentistry to achieve adequate strength and restore aesthetics. However, a perfect ideal restorative material has still eluded dentist. Dental amalgam is versatile material with self-sealing property, but is unaesthetic. Other restorative materials like, composites require conservative preparation, but exhibits polymerisation shrinkage resulting in microleakage. To overcome these drawbacks a high strength restorative material reinforced with ceramic and zirconia fillers known as zirconomer has been introduced. The aim of this study was to evaluate the micro-leakage of these three different restorative materials.

MATERIALS AND METHODS

Thirty non-carious human permanent first and second molars were utilized in this study. Class I cavities were prepared on the occlusal surface; cavities were then restored with amalgam, composite and zirconomer as per manufacture's instruction. All samples were stored for 24 hours in distilled water followed by thermocycling. The entire tooth surface was painted with two coats of varnish to within 1mm of the restoration margins. The teeth were immersed in dye. Teeth were sectioned and observed under stereomicroscope.

RESULTS

In this study the zirconomer exhibited the highest micro leakage as compared to composite and amalgam but composite having higher micro leakage as compared to amalgam and lower micro leakage as compared to zirconomer.

CONCLUSION

Even though composite and amalgam are being marketed aggressively and new material like zirconomer are on origin, amalgam still proves to be one of the best materials.