Effect of antimicrobial photodynamic therapy on microleakage of class cavities restored with composite resin

Effect of photodynamic therapy with two photosensitizers on the microtensile bond strength of a universal adhesive to affected dentin

BACKGROUND

This study aimed to evaluate the impact of photodynamic therapy (PDT) using two photosensitizers, methylene blue and indocyanine green, on the microtensile bond strength of a universal adhesive to caries-affected dentin.

METHODS

The occlusal enamel of 60 third molars was cut to expose the inner one-third of the dentin. Artificial caries were induced through a pH cycling process. The samples were divided into three groups: M (Methylene blue+ diode laser), I (Indocyanine green agents+ diode laser irradiation), and control. Each group was further divided into two subgroups according to the adhesive protocol (self-etch, total-etch). After restoring with Gradia composite resin, teeth were sectioned and exposed to 5000 thermal cycles. Microtensile bond strength was measured using a universal testing machine. The data were subjected to two- and one-way ANOVA and paired comparisons were performed by the Tamhane and Tukey tests.

RESULTS

The study found significant effects of the photosensitizer, etching pattern, and their interactions on the microtensile bond strength of composite resin to caries-affected dentin (P < 0.001). In the self-etching mode, PDT with indocyanine green exhibited significantly higher bond strength values compared to PDT with methylene blue (P = 0.001) and the control groups (P < 0.001). However, no significant differences were observed in the total-etch mode. (P = 0.54).

CONCLUSIONS

The etching mode played a more significant role in the bond strength when using the universal adhesive alongside PDT with methylene blue and indocyanine green. Employing two photosensitizers in PDT during the self-etch mode significantly increased the bond strength values.

Effect of varying functional monomers in experimental self-adhesive composites: polymerization kinetics, cell metabolism influence and sealing ability

The aim was to evaluate the effects of adding different functional monomers to experimental self-adhesive composites (SACs) on polymerization kinetics, cell metabolic activity, and sealing ability. SACs were formulated using urethane dimethacrylate as the base monomer and triethylene glycol dimethacrylate. Additionally, 10 wt.% of distinct functional monomers were added - 10-methacryloyloxydecyl dihydrogen phosphate, glycerol phosphate dimethacrylate (GPDM), 2-hydroxyethyl methacrylate (HEMA) or hydroxyethyl acrylamide (HEAA). ATR-FTIR was used to determine real-time polymerization kinetics (20 min,n= 3). The final extrapolated conversion and polymerization rates were determined (DC,max;Rp,max). TheDC,maxvalues were employed to calculate volumetric shrinkage. The MTT assay was performed on MDPC-23 cells using disc extracts at different concentrations (n= 8). Class V cavities were prepared in 60 sound human molars, assigned to six groups (n= 10), depending on the composite used and aging type (T0 or TC, if thermocycled for 10 000 cycles). One-way ANOVA, two-way, andKruskal-Wallistests were employed to treat the data (ɑ= 0.05). Varying the functional monomers had a large impact on DC,max, as confirmed by one-way ANOVA (p<0.001). The highest was obtained for HEMA (64 ± 3%). The HEMA and HEAA formulations were found to be significantly more toxic at concentrations below 100%. For microleakage, having a functional monomer or not did not show any improvement, irrespective of margin or aging period (Mann-Whitney U,p> 0.05). Larger functional monomers MDP and GPDM affected polymerization properties. Conversely, their acidity did not seem to be detrimental to cell metabolic activity. Regarding sealing ability, it seems that the functional monomers did not bring an advantage to the composites. Varying the functional monomer in SACs had a clear impact on the polymerization kinetics as well as on their cytotoxic potential. However, it did not confer better microleakage and sealing. Claiming self-adhesiveness based only on functional monomers seems dubious.

Caries affected disinfection using Phycocyanin activated by PDT, Holy Basil, and Ti-sapphire laser on adhesive bond strength, microleakage, and bond failure

AIM

To investigate the effect of different cavity disinfectants, Phycocyanin (PC), Ocimum Sanctum (OS), and Ti Sapphire Laser, on the bond integrity and microleakage of resin restorations.

MATERIAL AND METHOD

60 human mandibular molars were extracted and prepared based on ICDAS scores of 4 and 5. To obtain the CAD surface, a visual examination was supported by tactile sensation and a dye for caries detection. Samples were randomly allocated into 4 groups based on cavity disinfectants applied (n = 15). Group 1: Specimens disinfected with CHX, Group 2: Specimens disinfected with Ti sapphire laser, Group 3: Specimens disinfected with Phycocyanin activated by Photodynamic therapy, and Group 4: Specimens disinfected with OS. Following the disinfection of the CAD surfaces, composite bulk-fill restorative material was bonded to each specimen and all samples were subjected to thermocycling. Ten samples from each group underwent SBS testing performed on a universal testing machine. Five samples were subjected to a microleakage analysis.

RESULT

The maximum microleakage scores were displayed by Group 3: PC (0.521 nm) treated specimens. Whereas, and minimum microleakage was exhibited by Group 4: OS (0.471 nm). Group 4: OS (23.06±0.21 MPa) treated group displayed the maximum bond scores of resin adhesive to the CAD surface. However, Group 3: PC (21.67±0.24 MPa) treated specimens exhibited the lowest bond scores. Failure mode analysis revealed that among all the investigated groups the predominant type of failure was cohesive failure i.e., Group 1 (80%), Group 2 (80%), Group 3 (70%), and Group 4 (90%).

CONCLUSION

Ocimum Sanctum, Phycocyanin activated by Photodynamic therapy, and Ti-sapphire laser for disinfection of caries-affected dentin have shown promise in terms of improved bond strength and reduced microleakage.

Efficacy of methylene blue and curcumin mediated antimicrobial photodynamic therapy in the treatment of indirect pulp capping in permanent molar teeth

PURPOSE

This study aimed to evaluate the adhesive bond strength and antibacterial efficacy of methylene blue (MB)-mediated antimicrobial photodynamic therapy (aPDT) and curcumin (CUR)-mediated aPDT versus the conventional disinfectants, such as chlorhexidine gluconate (CHX) gel and sodium hypochlorite (NaOCl), for indirect pulp capping (IPC) treatment of permanent molars.

METHODS

One Hundred grossly carious human permanent molars were collected through non-traumatic extraction. All specimens were embedded in polyvinyl cross-sections to the cemento-enamel junction. The cavity preparation was conducted by grinding the samples using silicon carbide discs. After culturing Streptococcus mutans (S. mutans), a 10 µL of S. mutans suspension (10⁶ colony forming units/mL) was transferred in each tooth cavity and anaerobically incubated for 48 hours at 37°C. All specimens were randomly divided into 5 groups: Group-I: samples treated IPC; Group-II: samples treated with 2% CHX gel; Group-III: samples treated with 6% NaOCl; Group-IV: irradiation of prepared cavity with MB-mediated aPDT; and Group-V: irradiation of prepared cavity with CUR-mediated aPDT. After disinfection methods, the universal adhesive was used, and all specimens were restored using giomer. Eventually, confocal laser scanning microscopy, shear bond strength (SBS), micro-tensile bond strength (μTBS), four-point bending strength (4P-BS) analyses were performed, and the data were analyzed statistically.

RESULTS

At baseline, the highest SBS (48.8 ± 6.5 MPa), μTBS (54.3 ± 3.9 MPa), and 4P-BS (123 ± 32 MPa) scores were demonstrated by the samples treated with MB-mediated aPDT. However, after 12 months of storage, the highest SBS (42.3 ± 3.9 MPa) and μTBS (45.2 ± 6.6 MPa) scores were shown by samples treated with MB-mediated aPDT, while CUR-mediated aPDT treated samples demonstrated the highest 4P-BS scores (70 ± 18 MPa). Moreover, the highest antibacterial activity against S. mutans was shown by the samples treated with MB-mediated aPDT.

CONCLUSIONS

The application of aPDT, especially MB-mediated, demonstrated superior SBS, μTBS, and 4P-BS values as well as antibacterial activity against S. mutans as compared to 2% CHX gel and 6% NaOCl as cavity disinfectants for IPC treatment of permanent molars.

[Evaluation of the adhesive resistance of a composite resin to dentin treated with chlorhexidine and photodynamic therapy. in vitro study]

Introduction

Photodynamic therapy consists of the application of a light with an adequate wavelength on the cavities prior to the application of a photosensitizing agent, with the purpose of eliminating remnants of microorganisms remaining after instrumentation.

Objective

Evaluate the adhesive resistance to dentin treated with 2% chlorhexidine and photodynamic therapy with a 660nm diode prior to the insertion of composite resin.

Materials an Methods

In this in vitro experimental study, 60 bovine mandibular incisors were collected, After dentin wear, the samples were divided into 3 groups, with 20 samples per group: control group (no therapy was applied), 2% chlorhexidine, and 660nm diode laser (photosensitizer: methylene blue). Adhesive strength test was measured by shear test compared to kruskall-wallis test and post-hoc pairwise comparison.

Results

The average values from highest to lowest result with the CHX (14.82 ± 3.14), followed by the 660nm diode laser (14.77 ± 4.02) and the control group (9.25 ± 1.16). Similar groups of 660 nm diode laser and 2% CHX changed values (P>0.05), but significantly higher than the control group (P<0.001). Conclusion: Photodynamic therapy increased adhesive resistance as well as chlorhexidine, both therapies presented an increase in adhesive resistance compared to the control group.

The in vitro effect of antimicrobial photodynamic therapy with toluidine blue and indocyanine green on microleakage of class V cavities

INTRODUCTION

Considering the importance of disinfecting dentin and enamel after cavity preparation and the possible effect of disinfection methods on induction of various reactions in the tooth structure the aim of the present study was to evaluate microleakage of composite resin restoration after disinfecting the prepared dentin and enamel surface with antimicrobial photodynamic therapy (aPDT) with toluidine blue (TBO) and indocyanine green (ICG).

MATERIALS AND METHODS

Standard class V cavities were prepared on buccal surface of 71 human premolar teeth. The samples were randomly divided into 3 groups based on disinfection method: Group 1: conventional disinfection method with Phosphoric acid 37% as the control; Group 2: aPDT with TBO and diode laser with wavelength of 635 nm; Group 3: aPDT with ICG and diode laser with wavelength of 808 nm. All the cavities were restored with composite resin (3M™ Filtek™ Z250). After thermocycling and immersing in 0.5% basic fuchsin, the samples were prepared for microleakage evaluation under a stereomicroscope. Data was analyzed with Kruskal-Wallis and Wilcoxon signed-rank tests at P < 0.05.

RESULTS

There were no significant differences in the microleakage of occlusal and gingival margins between the TBO and control groups (P > 0.05). Also, the microleackage of occlusal margins between groups was not significantly different (P > 0.05) but microleackage of gingival margins of ICG group was lower than two other groups in a meaningful way (P < 0.05).

CONCLUSION

Photodynamic therapy with ICG as disinfecting agent in cavity preparations before composite resin restorations decreases the microleackage of gingival margins.

Effect of photodynamic therapy on resin-dentin bonding interface using different illumination time

OBJECTIVES

The aim of the present study was to evaluate the effect of photodynamic therapy(PDT) on the resin-dentin bonding interface using different illumination time.

METHODS

Seventy completed, isolated molar teeth were collected for this study, sixty of them were used in microtensile bond strength tests. These teeth were initially divided randomly in two main groups(n=30) by the random number table method upon the type of using illumination or not respectively. Then these groups followed by dividing each category in five subgroups(n=6): group A, group B1,group B2, group B3, group B4, group a, group b1, group b2, group b3, group b4. After different treatment, the remaining teeth were made specimens which were observed the fracture modes and interfaces under a stereomicroscope and a scanning electron microscope(SEM). The dentin permeability of the specimens were evaluated by a laser scanning confocal microscope(LSCM). To detect significance difference between means of different groups analysis of variance(ANOVA) was performed followed by LSD-t tests.

RESULTS

There was a significant statistical difference in the microtensile bond strength of the different illumination time of PDT between four experimental groups and the control (P<0.05).

CONCLUSION

With the increase of the illumination time in PDT, the bonding strength between resin and dentin decreased gradually.

Effect of antimicrobial photodynamic therapy with different photosensitizers and adhesion protocol on the bond strength of resin composite to sound dentin

OBJECTIVES

The aim of this study is to evaluate the influence of the antimicrobial photodynamic therapy with phycocyanin and toluidine blue on the bond strength of resin composite to the sound dentin.

MATERIALS AND METHODS

The samples include 120 tooth blocks taken from 60 human extracted sound third molar teeth. They were randomly divided into 12 groups and disinfected with two different photosensitizers (Phycocyanin and Toluidine blue) activated by 635 nm diode laser for aPDT procedure. Then two different protocols (total-etch and self-etch) of universal adhesive system (G-Premio BOND, GC Dental Products CORP. Japan) were applied. The samples then filled with resin composite (Gradia® Direct, GC Dental Products CORP. Japan). After 10000 cycles of thermocycling, all samples were subjected to the micro shear bond strength (μSBS) test using a universal testing machine (1 mm/min). The data were analyzed with One Way ANOVA.

RESULTS

The effect of aPDT using both photosensitizers (phycocyanin and toluidine blue O) on the bonding strength to dentin was not significant (P>0.05). However, the bonding strength of total etch groups was reduced significantly (P<0.05) after aPDT using both photosensitizers. Phycocyanin self-etch group showed the greatest bonding strength (19.48 ± 3.89 MPa) in comparison to other aPDT groups. No significant reduction after thermocycling in dentin bond strength was observed in all groups (P>0.05), with exception of control total etch groups, which showed significant difference (P<0.05).

CONCLUSION

aPDT using toluidine blue O and phycocyanin has no adverse effect on bonding to sound dentin when using universal adhesive in self-etch protocol.

CLINICAL RELEVANCE

Phycocyanin is more recommended to be used in aPDT in comparison to toluidine blue as a natural photosensitizer.

Challenging the Concept that OptiBond FL and Clearfil SE Bond in NCCLs Are Gold Standard Adhesives: A Systematic Review and Meta-analysis

PURPOSE

The following PICO (Patient/Population, Intervention, Comparison, and Outcomes) question was proposed: "Are retention rates of composite resin restorations in noncarious cervical lesions (NCCLs) when using adhesives considered "gold standard" (OptiBond FL and Clearfil SE Bond) higher than those obtained with other adhesives brands"?

METHODS

A search was performed in February 2019 (updated in November 2019) in the PubMed/MEDLINE, EMBASE, LILACS, BBO, Web of Science, Cochrane Library, Grey Literature, and IADR abstracts (1990-2018); unpublished and ongoing trial registries, dissertations, and theses were also searched. Only randomized clinical trials (RCTs) conducted in NCCLs that compared either OptiBond FL or Clearfil SE Bond adhesive with other commercially available adhesives were included. The risk of bias (RoB) was applied by using the Cochrane Collaboration tool. A meta-analysis was performed for retention rates at different follow-up times using a random effects model for both the adhesives. Heterogeneity was assessed with the Cochran Q test and I2 statistics. Grading of Recommendations: Assessment, Development and Evaluation (GRADE) assessed the quality of evidence.

RESULTS

After removal of duplicates and noneligible articles, 25 studies remained for qualitative synthesis, as one study was common to the two adhesives, of which 9 studies were used for the OptiBond FL meta-analysis and 14 for the Clearfil SE Bond meta-analysis. No significant differences were observed for retention rates in follow-up periods of 12-24 months (p=0.97), 36-48 months (p=0.72), or 108-156 months (p=0.73) for OptiBond FL; and for 12-24 months (p=0.10) and 36-48 months (p=0.17) for Clearfil SE Bond. A significant difference was only found for OptiBond FL at 60-96 months (p=0.02), but only three studies were included in this meta-analysis.

CONCLUSIONS

The evidence from available RCTs conducted in NCCLs that compared OptiBond FL or Clearfil SE Bond does not support the widespread concept that these adhesives are better than any other competitive brands available in the dental market.

Shear bond strength of resin modified glass ionomer cement following photodynamic therapy, Er,Cr:YSGG and chlorhexidine in hypoplastic primary teeth

PURPOSE

This study investigates the micro shear bond strength of resin-modified glass ionomer cement (RMGIC) bonded to hypoplastic teeth after the application of chlorhexidine (CHX), sodium hypochlorite (NaOCl), Er;Cr:YSGG and methylene blue mediated antimicrobial photodynamic therapy (APDT).

METHODS

A total sample of 60 erupted and extracted hypoplastic teeth collected from < 16 years children were subjected to different conditioning protocols including control group that involved bonding of hypoplastic teeth with RMGIC; CHX and NaOCl groups that included hypoplastic enamel being treated with 0.2% CHX and 2% NaOCl solution for 30 s followed by rinsing and drying for 5 s, MB-PDT group involved methylene blue photosensitizer and Er,Cr:YSGG group. All specimens were processed for microshear bond strength in a universal tester. The fractured surface was examined using a stereomicroscope at 40 × magnification and categorized under adhesive, cohesive and mixed.

RESULTS

The highest microshear bond strength was noted for the control group (∼29 MPa). Whereas the specimens conditioned by NaOCl showed the lowest microshear bond strength (∼17 MPa). Among the treatment groups, APDT showed the highest bond strength values (∼22 MPa) as compared to chemical disinfection protocols. However, Er, Cr:YSGG showed slightly lower microshear bond strength as compared to APDT. No significant difference was noted between CHX and NaOCl groups (p > 0.05). There was a statistically significant difference when all the groups were compared together (p < 0.05). Microscopic analysis revealed that specimens bonded after APDT showed the highest adhesive failures (70%). The highest cohesive failures were seen in NaOCl group (40%). The mixed type of failures was seen in the control groups with none appearing for chemical disinfection protocols.

CONCLUSIONS

This study concludes that APDT could be a potential therapeutic strategy for increasing the microshear bond strength of RMGIC to hypoplastic enamel.

Influence of methylthioninium chloride, curcumin and Er, Cr: YSGG on caries affected dentin bonded to bioactive and conventional bulk fill dental restorative material

AIM

The study aimed to determine the influence of Er, Cr: YSGG (ECL), methylene blue photosensitizer (MBP), and curcumin photosensitizer (CP) disinfection on CAD and its bond strength and microleakage to bioactive (BA) and multicore (MC) bulk-fill composite.

MATERIALS AND METHODS

Sixty carious mandibular molars were collected based on the criteria of ICDAS Code 6 (International Caries Detection and Assessment system). Specimens were embedded in polyvinyl pipes up to CEJ and subjected to preparation of standard class II cavity leaving CAD in situ for bonding. All samples were randomly assigned to eight groups based on disinfection regimes and type of bulk-fill material. Samples in group 5 and 6 didn't undergo any disinfection; group 1: ECL + BA, group 2: ECL+ MC; group 3 MBP + BA, group 4: MBP + MC; group 5: Conventional Etch and Rinse + BA (Control), group 6 Conventional Etch and Rinse + MC (Control); group 7: CP +BA and group 8 CP+MC. Specimens were tested for SBS using a universal testing machine and the debonded surfaces were evaluated under a stereomicroscope to determine modes of failure. A dye penetration test was performed for microleakage assessment. For intergroup comparison test analysis of variance (ANOVA) was performed using means and standard deviation from each group. Tukey HSD was used for multiple group comparison tests. The level of significance was established at p < 0.05.

RESULTS

The maximum mean bond strength was shown by group 6 (18.96 ± 0.31 MPa) conventional etch and rinse+ MC (control). Whereas, the minimum SBS was recorded in specimens of group 7 CP +BA (13.04 ± 0.81 MPa). SBS values among group 3 (14.05 ± 0.10 MPa- MBP+BA), group 4 (13.66 ± 0.39- MBP+MC) group 7 (13.04 ± 0.81 MPa- CP +BA and group 8 (14.21 ± 0.59 MPa- CP+MC) were found to be comparable (p>0.05). There was no statistically significant difference among the study groups concerning microleakage (p >0.05).

CONCLUSION

CAD treated with ECL for the adhesive bonding of BA and conventional bulk-fill composite MC has shown potential to be used clinically. Moreover, MBP and CP for conditioning of CAD need further investigation.

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.

Impact of riboflavin and curcumin mediated photodynamic therapy and Er,Cr:YSGG on microleakage of class V resin glass ionomer restorations in permanent molar teeth

PURPOSE

The present study aimed to evaluate the impact of PDT using curcumin and riboflavin as photosensitizers and Er,Cr:YSGG on microleakage in class V RMGIC restorations in permanent teeth.

MATERIALS AND METHODS

Eighty permanent molars were investigated and randomly divided into 4 groups: control group: resin-modified glass ionomer restoration with no treatment, R-PDT: PDT with riboflavin, Cu-PDT: PDT with curcumin (Cu) and, Er,Cr:YSGG: laser application. All the teeth in each group were restored with the help of RMGIC. The samples were dipped for 24 h in 0.5 % Fuchsine solution, and subsequently fixed in acrylic resin-based molds. Microleakage scores were estimated considering both cervical and occlusal boundaries. Intergroup comparisons were made at each margin, and intragroup comparisons made at the cervical and occlusal margins. The Shapiro Wilk test was used to check the normality of the values. Whereas, the analysis of data was conducted using SPSS version 25 via the Kruskal-Wallis and Wilcoxon tests. P < 0.05 was contemplated to be statistically important.

RESULTS

A high frequency (95%) of the enamel walls were not penetrated when subjected to treatment with R-PDT, followed by Cu-PDT and Er,Cr:YSGG. The highest amount of microleakage was observed (55%) Cu-PDT at the site of the cavity near the cementum. The least amount of microleakage was observed in the control group. A statistically significant difference in microleakage was noted at the cervical wall (p=0.015), while no significant difference was seen at the occlusal wall (p=0.789) between the groups. A significant difference was noted at the cervical wall between the control and R-PDT group (p=0.021) and Cu-PDT group (p=0.005), respectively. A significant difference in microleakage was observed when occlusal was compared with cervical walls within each group (p<0.05).

CONCLUSION

Photosensitizers using riboflavin and curcumin may reduce the microleakage within the enamel surface restored with RMGIC in class V lesions that may not interfere with bonding. However, extreme caution should be taken while considering riboflavin and curcumin for class V RMGIC restorations extending to cementum surface.

Bonding of an ion-releasing restorative material to caries-affected dentin disinfected with photodynamic therapy, Er,Cr:YSGG laser, and chemical disinfectants

AIM

The study aimed to evaluate the microtensile bond strength (μTBS) of giomer, an ion-releasing restorative material, to caries-affected dentin (CAD) when different cavity disinfectant protocols were applied before the restoration.

MATERIAL AND METHODS

Thirty extracted non-carious human third molars were embedded in acrylic resin. The occlusal portions of the samples were excised using an IsoMet saw. After creating artificial caries, samples were divided into six groups (n = 12): sound dentin with no disinfection (Group SD), CAD with no disinfection (Group CAD), CAD disinfected with 2% chlorhexidine gluconate (Group CHX), CAD disinfected with 6% NaOCl (Group NaOCl), CAD disinfected with photodynamic therapy with methylene blue photosensitizer (Group PDT), and CAD disinfected with Er,Cr:YSGG (Group ECYL). Following disinfection protocols, the universal adhesive was applied, and all samples were restored using giomer. Subsequently, μTBS analyses were performed, and data were analyzed statistically.

RESULTS

The highest μTBS values were obtained from the SD and CAD groups, which exhibited no statistical differences (p > 0.05). The PDT and ECYL groups had higher μTBS values compared with the CHX and NaOCl groups (p < 0.05), and all disinfection protocols decreased the bond strength to CAD (p < 0.05).

CONCLUSION

The microtensile bond strength of disinfected CAD was greater with Er,Cr:YSGG laser and photodynamic therapy treatment than with chemical disinfectants. Giomer may enhance the bond strength to CAD, which has a weaker bonding potential than sound dentin due to structural differences. However, disinfection protocols adversely affect adhesion between the restorative material and CAD.

The effect of antimicrobial photodynamic therapy on shear bond strength of orthodontic bracket: An in vitro study

OBJECTIVES

The aim of this study was to evaluate the effect of antimicrobial photodynamic therapy (aPDT) with methylene blue (MB) and indocyanine green (ICG) on bond strength of orthodontic brackets to enamel.

MATERIALS AND METHODS

A total of 45 non-carious and sound human premolar teeth were used in this study. All teeth were examined under a stereomicroscope at ×10 magnification. The samples were divided to 3 groups including no treatment (control group), aPDT with MB and 660 nm diode laser and aPDT with ICG and 808 nm diode laser. After aPDT procedure, orthodontic brackets were bonded to enamel surfaces. Then, the samples were thermocycled for 5000 cycles between 5° and 55° C in water bath. The brackets were then debonded using a universal testing machine. The adhesive remnant index (ARI) score and SEM microscope evaluation were assessed. One-way analysis of variance (ANOVA) with Post-hoc test were used to compare the SBS values among groups.

RESULTS

The highest SBS mean value was presented in group 1 (control) (31.98 ± 6.36). Whereas, the lowest SBS mean value was observed in group 3 (aPDT with ICG) (24.11 ± 5.78). There were significant differences in SBS values between control and aPDT groups (P < 0.05). Some superficial porosity and irregularity was presented following aPDT on surface of enamel when examined by scanning electron microscope. The mode of failure was mostly score 0 and score 1 in all groups.

CONCLUSION

MB and ICG mediated antimicrobial photodynamic therapy both reduced the bond strength of orthodontic brackets compared to control group.

Photoactivated resveratrol controls intradermal infection by Staphylococcus aureus in mice: a pilot study

Staphylococcus aureus is one of the main causative agent of infections acquired in both community and hospital environment. In this context, photodynamic therapy (PDT) consists in using a photosensitizer that, activated by light, evokes the formation of reactive oxygen species (ROS), which lead to the death of microorganisms due to oxidative damage; it is useful tool since this action, harmful to pathogens, does not significantly injure human cells. In view of this, this work proposes a more in-depth study on the use of resveratrol (RSV) as a possible photosensitizer. It was observed, in the intradermal infection model in animals' ear dermis, that photoactivated resveratrol promotes an increase in myeloperoxidase expression with reduced bacterial load in the draining lymph node. Besides that, the draining lymph node of the animals treated with photoactivated RSV controls inflammation through IL-10 production. These are pioneers data and this work being a pilot study; then, other works must be conducted with the objective of elucidate the photoactivated resveratrol mechanism of action.

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.

Influence of antimicrobial photodynamic therapy in carious lesion. Randomized split-mouth clinical trial in primary molars

BACKGROUND

The literature presents many studies regarding photodynamic antimicrobial therapy (aPDT). However, the great variety of protocols to be used can directly influence its effectiveness in reducing microorganisms. The aim of this randomized split-mouth clinical study was to evaluate the effect of aPDT in the reduction of Streptococcus mutans and their effect on restorations performed.

METHODS

Twenty children between 6 and 8 years old with active caries and dentin cavitation, located on the occlusal surface of homologous primary molars were included. The selective removal of carious tissue was performed in both molars, than one was subsequently restored and the other received aPDT treatment on the affected dentin with low intensity laser (InGaAlP) associated to 0.005% methylene blue photosensitizer before restoration. Dentin collections were performed only in the tooth submitted to aPDT in three moments: before and after selective caries removal and after application of aPDT. The restorations were analyzed after polishing and after 6 months using United States Public Health Service (USPHS) method. Data were analyzed using ANOVA with repeated measures and Bonferroni post-hoc test with a significance level of 5%.

RESULTS

There was a significant reduction on the amount of microorganisms after selective caries removal (p = 0.04) and also after the application of aPDT (p = 0.01). The reduction of S. mutans CFU was of 76.4% after caries removal, but associated with aPDT was 92.6%. After 6 months of clinical evaluation, no difference between groups was found for retention, marginal adaptation, color, marginal discoloration, and secondary caries.

CONCLUSIONS

aPDT can be used as an additional treatment against cariogenic microorganisms after selective caries removal without compromising composite resin restorations.