Evaluating the effect of strontium ranelate and photobiomodulation on cementogenic and osteogenic differentiation of buccal fat pad-derived stem cells: An in vitro study.

This study aimed to analyze the impact of strontium ranelate (Str), photobiomodulation (PBM), or their combination of the proliferation, osteogenic differentiation, and cementogenic differentiation of buccal fat pad-derived stem cells. BFPdSCs were exposed to one of the following interventions: (1) PBM (660 nm), (2) PBM (660 nm) + Str, (3) PBM (880 nm), (4) PBM (880 nm) + Str, (5) Str. All study groups had significantly higher osteogenic differentiation than the control group (p < 0.05), and no significant difference existed between the 660 and 808 nm groups (p = 0.97). Compared to the Str group, 660 nm and 880 nm group samples had significantly lower osteogenic differentiation (p < 0.0001), while other groups did not show a significant difference. Regarding cementogenic differentiation, the 660 nm group showed higher values than the 808 nm group (p < 0.01). Compared with the Str group, 660 nm, 660 nm + Str, and 808 nm + Str groups showed significantly higher gene expression (p < 0.05). In the case of osteogenic differentiation, although photobiomodulation alone had a lower inducing effect than strontium ranelate, combining 808 nm diode lasers and strontium ranelate may provide the best results. Moreover, using a 660 nm diode laser and exposing stem cells to strontium ranelate can be the most effective approach to induce cementogenic differentiation.

Evaluation of adding nanosized natural zeolite to photodynamic therapy against P. gingivalis biofilm on titanium disks.

BACKGROUND: Antibacterial photodynamic therapy (aPDT) can be used as an adjunctive therapy for eliminating bacterial biofilm. The application of nanotechnology in aPDT, which is a growing trend, has improved the delivery of photosensitizers (PSs) into microorganisms. Encapsulation of molecules and ions is considered an outstanding potential feature of zeolites. This study sought to enhance the effect of aPDT using a diode laser (810 nm) with a potential PS, indocyanine green (ICG), combined with nanosized natural zeolite (NZ), against biofilm of P. gingivalis on sandblasted, large-grit, and acid-etched (SLA) implant titanium disks surface. METHODS: A bacterial suspension of standard P. gingivalis (™ATCC® 33277) strains was prepared. To prepare bacterial biofilm, the titanium disks were added to 48 microtubes containing bacterial suspension, and divided into eight groups, i.e., the control groups (positive and negative), and 6 test groups (ICG; NZ; Diod laser; NZ+ICG; aPDT; NZ+aPDT). After the treatments, the total number of colony-forming units per disk was calculated. Finally, the data was analyzed, and the eight groups were compared together. RESULTS: The highest reduction in the number of P. gingivalis was seen in group 8 (NZ+aPDT) with 3.55 log10 CFU/ml and the antibacterial effect of 45.7% compared with the negative control group. Conversley, group 5 (Diode Laser solely) represented the highest mean of colony count with the lowest antibacterial effects per disk (6.42 log10 CFU/ml, 1.8%). CONCLUSIONS: The antibacterial effect of NZ+aPDT against P. gingivalis biofilm was noticeable. Thus, adding NZ to ICG improved the result of aPDT in this study.

Sub-lethal doses of photodynamic therapy affect biofilm formation ability and metabolic activity of Enterococcus faecalis.

BACKGROUND: During photodynamic therapy (PDT) in the treatment of a primary endodontic infection, it is extremely likely that microorganisms would be exposed to sub-lethal doses of PDT (sPDT). Although sPDT cannot kill microorganisms, it can considerably influence microbial virulence. This study was conducted to characterize the effect of sPDT using toluidine blue O (TBO), methylene blue (MB), and indocyanine green (ICG) on biofilm formation ability and metabolic activity of Enterococcus faecalis. METHODS: The antimetabolic and antibiofilm potential of ICG-, TBO-, and MB-sPDT against E. faecalis was analyzed at sub-lethal doses (1/2-1/64 minimum inhibitory concentration) using the XTT reduction assay, crystal violet assay, and scanning electron microscopy. RESULTS: Higher doses of sPDT adversely affected biofilm formation ability and metabolic activity. ICG-, TBO-, and MB-PDT at a maximum sub-lethal dose markedly reduced the formation of biofilm up to 42.8%, 22.6%, and 19.5%, respectively. ICG-, TBO-, and MB-sPDT showed a marked reduction in bacterial metabolic activity by 98%, 94%, and 82%, respectively. ICG-PDT showed a stronger inhibitory effect on biofilm formation in E. faecalis than MB- and TBO-PDT at sub-lethal levels. Interestingly, a gradual increase in metabolic activity and biofilm formation upon exposure to a lower dose of test sPDT were observed. CONCLUSION: sPDT showed dual effect on biofilm formation ability and metabolic activity of E. faecalis. High doses revealed antimetabolic and antibiofilm potential activity, whereas lower doses had conflicting results. Hence, when PDT is prescribed in clinical settings, the dose of PDT used in vivo should be taken into consideration.

Evaluation of antimicrobial photodynamic therapy with indocyanine green and curcumin on human gingival fibroblast cells: An in vitro photocytotoxicity investigation.

UNLABELLED: Recent investigations have suggested that antimicrobial photodynamic therapy (aPDT) can be an alternative treatment for the management of periodontal infections. However, currently there is very limited data regarding the photocytotoxicity of this method on human gingival fibroblast (HuGu) cells. AIM: The in vitro optimal concentrations of indocyanine green (ICG) and curcumin as photosensitizers (PSs) and the irradiation time of diode laser emission were evaluated by assessing the photocytotoxicity of the treatment on HuGu cells. MATERIALS AND METHOD: Monolayers of HuGu cells were incubated with various final concentrations of ICG (500, 750, 1000, 1250, 1500, 1750, and 2000µg/ml) and curcumin (3, 4, 5, 10, and 20mM). Three exposure times of the diode laser (30s, 60s, and 2×30s irradiation with an interval of 1min between each) and one of exposure time of 5min for LED were tested; cell viability was determined using neutral red assay. Chlorhexidine (CHX) as a gold standard antimicrobial agent for periodontal disease was considered as a control group. RESULTS: ICG and curcumin significantly reduced HuGu cell viability at concentrations below 1000µg/ml and 10mM, respectively (P<0.01). Cytotoxicity was higher when the cells were treated for 2×30s irradiation with an interval of 1min and then again exposed to the laser for 30s (2% and 0.1%). CHX demonstrated no significant reduction in HuGu cell survival. CONCLUSION: Photocytotoxicity is influenced by PS concentration, exposure time of PS, and time of irradiation. High doses of ICG and curcumin with lowest exposure time of light source and without cytotoxic effects may be an effective strategy for aPDT as an alternative treatment for periodontal disease.

Comparison of Microleakage of Glass Ionomer Restoration in Primary Teeth Prepared by Er: YAG Laser and the Conventional Method.

OBJECTIVE: One of the main criteria in evaluating the restorative materials is the degree of microleakage. The aim of this study was to compare the microleakage of glass ionomer restored cavities prepared by Er:YAG laser or turbine and bur. MATERIALS AND METHODS: Twenty extracted caries-free deciduous posterior teeth were selected for this study. The teeth were randomly divided into two groups for cavity preparation. Cavities in group one were prepared by high speed turbine and bur. In the second group, Er:YAG laser with a 3W output power, 300 mJ energy and 10 Hz frequency was used. Cavities were restored with GC Fuji II LC. After thermocycling, the samples were immersed into 0.5% methylene blue solution. They were sectioned for examination under optic microscope. RESULTS: The Wilcoxon signed ranks test showed no significant difference between microleakage of the laser group and the conventional group (P>0.05). CONCLUSION: Er:YAG laser with its advantages in pediatric dentistry may be suggested as an alternative device for cavity preparation.

The effect of low level laser therapy on pain reduction after third molar surgery.

AIM: The aim of this study was to evaluate the effects of low level laser on the postoperative pain of patients who had to undergo third molar surgery. METHODS: In a randomized clinical setting, 100 patients were assigned to two groups of 50 in each. Every patient underwent surgical removal of one mandibular third molar (with osteotomy). After suturing the flap, the soft laser was applied to every patient. In group I laser radiation was applied by the dental assistant with output power of 100 mW, in continuous mode with sweeping motion, in group II, the laser hand piece was only brought into position without releasing energy, so that no patient knew which group he belonged to. The patient was given a pain evaluation form where they could determine their individual pain level and duration. RESULTS: The statistical tests showed significant difference in pain level between laser and control group (P<0.001) but no significant difference found in pain duration in two groups (P=0.019). CONCLUSION: The result of this study verifies the positive effect of the soft-laser therapy in the postoperative complication after third molar extraction.

Comparison of Shear Bond Strength of Orthodontic Brackets Bonded to Enamel Prepared By Er:YAG Laser and Conventional Acid-Etching.

INTRODUCTION: The purpose of this study was to compare shear bond strength (SBS) of orthodontic brackets bonded to enamel prepared by Er:YAG laser with two different powers and conventional acid-etching. MATERIALS AND METHODS: Forty-five human premolars extracted for orthodontic purposes were randomly assigned to three groups based on conditioning method: Group 1- conventional etching with 37% phosphoric acid; Group 2- irradiation with Er:YAG laser at 1 W; and Group 3- irradiation with Er:YAG laser at 1.5 W. Metal brackets were bonded on prepared enamel using a light-cured composite. All groups were subjected to thermocycling process. Then, the specimens mounted in auto-cure acryle and shear bond strength were measured using a universal testing machine with a crosshead speed of 0.5 mm per second. After debonding, the amount of resin remaining on the teeth was determined using the adhesive remnant index (ARI) scored 1 to 5. One-way analysis of variance was used to compare shear bond strengths and the Kruskal-Wallis test was performed to evaluate differences in the ARI for different etching types. RESULTS: The mean and standard deviation of conventional acid-etch group, 1W laser group and 1.5W laser group was 3.82 ± 1.16, 6.97 ± 3.64 and 6.93 ± 4.87, respectively. CONCLUSION: The mean SBS obtained with an Er:YAG laser operated at 1W or 1.5W is approximately similar to that of conventional etching. However, the high variability of values in bond strength of irradiated enamel should be considered to find the appropriate parameters for applying Er:YAG laser as a favorable alternative for surface conditioning.