Comparison of the effects of Er,Cr:YSGG laser and different cavity disinfection agents on microleakage of current adhesives

Impact of acid and laser etching of enamel on microleakage in different adhesive systems

This study aimed to evaluate the microleakage of light-cured and self-cured adhesives on enamel surfaces selectively etched with Er, Cr: YSGG laser or 35% phosphoric acid. A total of 60 class V cavities were prepared 1 mm above the cemento-enamel junction (CEJ). The specimens were randomly divided into six groups. Group 1: Clearfil SE Bond with no conditioning, Group 2: Tokuyama Universal Bond with no conditioning, Group 3: Clearfil SE Bond conditioned with 35% phosphoric acid, Group 4: Tokuyama Universal Bond conditioned with 35% phosphoric acid, Group 5: Clearfil SE Bond conditioned with Er, Cr: YSGG laser and Group 6: Tokuyama Universal Bond conditioned with Er, Cr: YSGG laser. Microleakage was evaluated qualitatively (visually) and quantitatively (ImageJ). The data were analyzed using IBM SPSS V23 and submitted to Kruskal-Wallis and Wilcoxon tests. The significance level was set at p < 0.05. In all evaluation methods, the microleakage scores exhibit significant differences (p*<0.001). Group 1 and Group 3 exhibited similar and lower microleakage values than the Group 5. In the occlusal margin, the microleakage values were similar in Group 2, Group 4, and Group 6, whereas in the gingival margin Group 4 showed significantly lower leakage compared to Group 2. Regardless of the etching protocols and adhesive systems used, less microleakage was observed on the occlusal surface than on the gingival surface. Phosphoric acid etching provides better results than laser etching for enamel surface treatment on both occlusal and gingival surfaces.

Disinfection of caries-affected dentin using potassium titanyl phosphate laser, Rose bengal and Ozonated water on shear bond strength of deciduous teeth

AIM

To assess the efficacy of disinfection of caries-effected dentin (CAD) using KTP laser and different decontamination methods using ozonated water (OW), Rose Bengal photosensitizer (RBP), chlorhexidine (CHX), and Er, YAG laser on the shear bond strength (SBS) of adhesive resin bonded to deciduous teeth.

MATERIAL AND METHODS

A total of 50 extracted and radiographically verified carious primary molars were collected and scrutinized according to ICDAS criteria. Specimens were allocated randomly into five groups (n = 10) as per the type of CAD disinfectants. KTP laser, OW, RBP, CHX (control), and Er, YAG laser. After cavity sanitization, a resin adhesive (prime and bond NT) was smeared on the dentinal exterior followed by incremental composite filling. SBS evaluation was performed by employing specimens in the universal testing machine. The debonded surface was assessed under 40x magnification in a stereomicroscope to ascertain fracture mode. Statistical analysis was done by using the ANOVA and the Post Hoc Tukey multiple comparison tests (p < 0.05).

RESULTS

The highest SBS was exhibited by group 2 i.e., when OW was employed for CAD disinfection (10.25 ± 0.24 MPa). Whereas, the lowest SBS bond value was unveiled by samples in group 3 when RBP was applied for dentin surface sanitization (7.85 ± 0.59 MPa).CAD disinfection with KTP laser (8.25 ± 0.41 MPa), CHX (8.19 ± 0.73 MPa), and RBP displayed comparable bond values (p > 0.05).

CONCLUSION

Ozonated water and Er, YAG laser could be employed as cavity disinfectants in primary teeth as they demonstrated better shear bond strength without jeopardizing the adhesive binding capacity of restorative resins bonded to caries-affected dentin.

Nanoparticle incorporated dentin bonding agent to caries effected dentin treated by photodynamic therapy, laser or chlorhexidine

PURPOSE

This study aims to evaluate the microtensile bond strength (µTBS) and failure modes of graphene nanoplatelets doped with hydroxyapatite (GNP-HA) modified self-etch dentin bonding agent (DBA) to caries effected dentin (CAD) after various conventional and laser disinfection protocols.

MATERIALS AND METHODS

Graphene nanoplatelets and HA nanoparticles were doped and incorporated in DBA. Fifty carious human molar teeth were used for the experiment. CAD specimens were divided into five groups (n=10/group) into CAD undergoing no disinfection treatment (Group-CAD), 2% chlorhexidine disinfection (Group-CHX), 6% NaOCl disinfection (Group-NaOCl), methylene blue assisted PDT (Group-MB-PDT), and Er,Cr:YSGG laser application (Group-Er,Cr:YSGG). Following the respective disinfection techniques, the GNP-HA modified adhesive was applied to all treated CAD surface. Subsequently µTBS and failure modes were analyzed.

RESULTS

Representative scanning electron microscope images (SEM images) of the synthesized GNP-HA indicated flakes of graphene with varying size lengthwise (>500 nm) with 1-2 nm width. The doped HA showed round and spherical morphology conjugated over the surface of the GNP measuring 40 -100 nm in diameter. CAD group that underwent no treatment represented the highest µTBS (29.43 MPa). Within the tested specimens, MB-PDT (22.37 MPa) and Er,Cr:YSGG (21.85 MPa) showed the highest µTBS values than CHX (15.69 MPa) and NaOCl (11.46 MPa). However, there was no significant difference between MB-PDT and Er,Cr:YSGG (p>0.05) and a significant difference existed between CHX and NaOCl (p<0.05). Equal distribution of cohesive and adhesive failures was noted for CAD, CHX and NaOCl treated specimens. A majority of adhesive failures existed in the MB-PDT groups. While admixed and adhesive failures were higher in Er,Cr:YSGG treated samples.

CONCLUSIONS

The outcome of this study suggests that CAD restored by GNP-HA modified self-etch adhesive showed highest bond strength after MB-PDT and Er,Cr:YSGG protocols with low amount of adhesive failure.

Evaluation of Stabilized Chlorine Dioxide in Terms of Antimicrobial Activity and Dentin Bond Strength

BACKGROUND

Antimicrobial agents are recommended for disinfection of the cavity following mechanical dental caries removal prior to application of restorative material. There is limited information about stabilized chlorine dioxide (ClO2) as a cavity disinfectant.

OBJECTIVE

The objective of this study is to determine the antimicrobial activity and effect on dentin bond strength of ClO2 compared to chlorhexidine digluconate (CHX), sodium hypochlorite (NaOCl) and ethanolic propolis extract (EPE).

METHODS

Antimicrobial activities of agents against oral pathogens (Staphylococcus aureus, Enterococcus faecalis, Streptococcus mutans, Lactobacillus acidophilus, Lactobacillus casei, Candida albicans, and Saccharomyces cerevisiae) and analyses of EPE were examined. Seventy-five mandibular third molars were sectioned, prepared and divided into five subgroups (n=15/group). Cavity disinfectants (2% CHX, 2.5% NaOCl, 30% EPE, 0.3% ClO2) were applied to etched dentin prior to adhesive and composite build-up. Shear bond strength (SBS) was evaluated with a universal testing machine at a crosshead speed of 0.5 mm/min. The SBS data were analyzed with one-way analysis of variance (ANOVA) and Tukey's post-hoc test (p <0.05). The failure modes were evaluated with a stereomicroscope.

RESULTS

It was determined that the compared disinfectants were showed different inhibition zone values against oral pathogens. ClO2 exhibited the highest antimicrobial activity, followed by CHX, NaOCI and EPE, respectively. No statistically significant difference was observed in the SBS values between the disinfectant treated groups and control group. The failure modes were predominantly mixed.

CONCLUSION

The use of 0.3% stabilized ClO2 as a cavity disinfectant agent exhibited high antimicrobial activity against oral pathogens and no adverse effects on SBS to etched dentin.

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 different polishing systems and drinks on the color stability of resin composite

AIM

The purpose of this study was to evaluate the color stability of resin composit using different finishing systems and drinks.

MATERIALS AND METHODS

Composit disks (5 mm diameter, 2 mm thickness) were prepared for each nanofilled composite using a brass mold. The specimens were divided into 5 finishing system groups Mylar strip (Mylar, DuPont, Wilmington, Del., USA), Soft Lex (3M(™) ESPE(™) St. Paul, MN, USA), Enhance (Dentsply-DeTrey GmbHD Konstanz, Germany), Hiluster (KerrHawe, Bioggio, Switzerland), Opti Disc (KerrHawe, Bioggio, Switzerland) and each group was divided into 10 subgroups (n = 10) and stored for 24 hours at 37°C in different drinks water coffee, coffee with sugar, tea, tea with sugar, diet coke, coke, light sour cherry juice or sour cherry juice. Color of all specimens was measured before and after exposure with a spectrophotometer using CIE L*a*b* relative, and color changes (ΔE*) were then calculated. The data were analyzed with a twoway analysis of variance (ANOVA), and mean values were compared by the Tukey HSD test (p = 0.05).

RESULTS

For the drinks, the lowest ΔE* values were observed in the water and highest ΔE* values were observed in sour cherry juice. When drinks with and without sugar were compared, all groups with sugar demonstrated a higher color difference than without sugar. For the different finishing systems, Mylar strip group demonstrated significantly highest color change; Enhance groups demonstrated significantly lowest color change.

CONCLUSION

Finishing treatments and storage solutions significantly affect the color stability of resin composite. The presence of sugar in drinks increased the color difference compared to drinks without composit.

CLINICAL SIGNIFICANCE

Polishing techniques and drinking drinks with sugar may affect the color of esthetic restorations.