Evaluation of antimicrobial photodynamic therapy on wounds infected by Staphylococcus aureus in animal models.

BACKGROUND: Antibiotic-resistant Staphylococcus aureus bacteria are one of the expanding challenges. The purpose of current study is to evaluate the antimicrobial effect of photodynamic therapy (aPDT) on wounds infected to Staphylococcus aureus. METHODS: In this study, 40 six-month-old rats were divided into 4 groups: control, photosensitizer (PS), laser, and aPDT. A full-thickness wound was created on their skin and it was infected by Staphylococcus aureus. For aPDT, the Indocyanine Green (Germany, Nürnberg, A.R.C. Laser, EmunDo) photosensitive agent and laser diod 810 nm (Germany, Nürnberg, A.R.C. Laser) was utilized. The wound healing procedure was monitored every 24 h until the 12th day with photography. The number of the bacteria was counted on the 12th day also. All results were compared using ANOVA and Tukey post hoc tests. Significance level was considered P-Value < 0.05. RESULTS: The average area of wound reduced in days 5-11th in photosensitizer, laser, and aPDT, respectively. The absolute colonization rate of bacteria in the wounds showed a significant decrease in two groups laser and aPDT compared to the control group. However, the lowest value was for the aPDT. CONCLUSION: In the conditions of this study, it emerged that aPDT and laser have an antimicrobial effect against antibiotic-resistant bacteria (particularly Staphylococcus aureus) and improve wound healing.

Combined effects of calcium hydroxide and photobiomodulation therapy on apexogenesis of immature permanent teeth in dogs.

Treatment of high-risk traumatic immature teeth due to incomplete root development is challenging. Apexogenesis is currently the ideal treatment option that allows normal root development. The purpose of this study was to evaluate the apexogenesis process of immature permanent teeth of dogs when co-administered with calcium hydroxide and photobiomodulation therapy (PBMT). A total of 36 immature permanent anterior and premolar teeth were selected from three 4-6-month-old dogs of Iranian mixed generation. The teeth were categorized into two groups, calcium hydroxide with laser irradiation (CHL) and calcium hydroxide without laser irradiation (CH). All the selected teeth received calcium hydroxide pulpotomy. After restoring teeth with amalgam, the CHL group received gallium­aluminum-arsenide (GaAlAs) diode laser (810 nm, 4.2 J/cm2, 0.3 W, 9 s,CW) on apical one-third of both buccal and lingual roots. The irradiation was repeated every 48 h for fourteen days. Intravenous tetracycline was used to observe newly formed dentin in the first, third, seventh, and fourteenth days. The distance between tetracycline lines (DTL) was examined by Fluorescence microscopy. Generalized estimating equations (GEE) were used for data analysis. In all assessments, the mean DTL were greater in the CHL group. However, the two groups had no significant differences in the amount of deposited dentin between the first and third, third and seventh, and first and seventh lines. Meanwhile, there was a significant difference between the two groups in terms of the distances between lines 7 and 14, 1 and 14 and also 3 to 14 (P < .001). In other words, from the 7th day onwards, there was a significant difference between the two groups. Within the limitation of this study, the combination therapy of PBMT and pulpotomy with calcium hydroxide accelerated apexogenesis in immature permanent dogs' teeth.

Photobiomodulation in Oral Medicine.

Objective: To provide a review of the literature about the photobiomodulation therapy (PBMT) dental treatment protocols in oral medicine based on validated clinical studies that have been published so far. Background data: The lack of effective therapies for the treatment of various types of oral diseases or the presence of invasive therapeutic methods along with the use of a wide range of medications has had a significant impact on the quality of life of these patients. PBMT as a noninvasive and nondrug method can play an influential role in the treatment of oral diseases. Methods: In this study, published clinical studies up to April 2019 were reviewed from library sources, Google Scholar, PubMed and Medline, Elsevier, Embase, Cochrane, Scopus, and Web of science (ISI). Results: In general, the findings of this study showed that PBMT has had a positive effect on the treatment of oral lichen planus, recurrent aphthous stomatitis, hyposalivation, pemphigus vulgaris, recurrent herpes simplex, burning mouth syndrome, bisphosphonate-related osteonecrosis of the jaw, trigeminal neuralgia, facial nerve paralysis, geographic tongue, and chronic sinusitis. Conclusions: PBMT can be effective (as an alternative treatment or in combination with other therapies) in improving symptoms or in the complete treatment of oral diseases. However, further clinical studies are still necessary to achieve more robust results.

Improved Wound Remodeling Correlates with Modulated TGF-beta Expression in Skin Diabetic Wounds Following Combined Red and Infrared Photobiomodulation Treatments.

Diabetic wounds are a major cause of morbidity among patients with poorly controlled blood glucose levels. Conventional empirical wound care strategies have shown limited efficacy, and there is an urgent need to develop novel therapeutic strategies. Photobiomodulation treatments have shown positive therapeutic effects in several cell culture and animal models. In this study, we examined wound healing in diabetic rats following treatments with two laser wavelengths, namely red (660 nm) and infrared (808 nm) individually and in combination as compared to routine wound dressings. Immunostaining for TGF-ß expression was performed at various times postwounding. We noted that the combination of red and infrared laser treatments correlated with decreased TGF-ß1 levels at late stages in healing. There was no statistical significance with any treatments at an earlier time point. This study emphasizes the role of appropriate laser treatment protocols in modulating wound healing and remodeling responses.

Effects of Photobiomodulation and Mesenchymal Stem Cells on Articular Cartilage Defects in a Rabbit Model.

OBJECTIVE: The aim of this study was to evaluate the effectiveness of the application of cultured autologous bone marrow mesenchymal stem cells (BMSCs) with scaffold and low-level laser therapy (LLLT) on the repair of articular cartilage defects in rabbits. BACKGROUND DATA: For healing of the articular cartilage defects, although positive effects of BMSCs and LLLT have been demonstrated, their combination effect is still unknown; therefore, we investigated combining these two techniques has a synergistic effect. MATERIALS AND METHODS: After bone marrow aspiration from 10 rabbits, BMSCs were isolated, cultured in monolayer, suspended on a type I collagen scaffold and then implanted onto a full-thickness osteochondral defect (4 mm in diameter), artificially made on the patellar groove of both knees in the same rabbits. Then a knee was selected randomly in each rabbit as the experimental group, and subjected to Ga-Al-As (810 nm) laser irradiation with energy density of 4 J/cm2 every other day for 3 weeks. As the control group, the other knee did not receive LLLT. After this period, animals were euthanized and osteochondral defects were evaluated by histomorphometric methods. RESULTS: No significant difference in new cartilage formation and inflammation was found between the groups (p > 0.05). However, there was significantly more new bone formation in the experimental group (p < 0.05). CONCLUSIONS: In terms of our research, although better healing in osteochondral defects was seen when combining BMSCs and LLLT compared with the use of BMSCs alone, this improvement was predominantly caused by new bone formation rather than new cartilage formation.

Effect of Photobiomodulation on Mesenchymal Stem Cells.

OBJECTIVE: The purpose of this study was to review available literature about the effect of photobiomodulation (PBM) on mesenchymal stem cells (MSCs). BACKGROUND DATA: The effects of coherent and noncoherent light sources such as low-level lasers and light-emitting diodes (LEDs) on cells and tissues, known as PBM, form the basis of photomedicine. This treatment technique effects cell function, proliferation, and migration, and plays an important role in tissue regeneration. Stem cells have been found to be helpful elements in tissue regeneration, and the combination of stem cell therapy and laser therapy appears to positively affect treatment results. MATERIALS AND METHODS: An electronic search in PubMed was conducted of publications from the previous 12 years. English language articles related to the subject were found using selected key words. The full texts of potentially suitable articles were assessed according to inclusion and exclusion criteria. RESULTS: After evaluation, 30 articles were deemed relevant according to the inclusion criteria. The energy density of the laser was 0.7-9 J/cm2. The power used for visible light was 30-110 mW and that used for infrared light was 50-800 mW. Nearly all studies showed that low-level laser therapy had a positive effect on cell proliferation. Similar outcomes were found for LED; however, some studies suggest that the laser alone is not effective, and should be used as an adjunct tool. CONCLUSIONS: PBM has positive effects on MSCs. This review concluded that doses of 0.7-4 J/cm2 and wavelengths of 600-700 nm are appropriate for light therapy. The results were dependent upon different parameters; therefore, optimization of parameters used in light therapy to obtain favorable results is required to provide more accurate comparison.

Evaluation of fibroblast attachment in root conditioning with Er, Cr:YSGG laser versus EDTA: a SEM study.

The regeneration of periodontal support is a main concern in periodontal therapy. This study aims to investigate the efficacy of Er, Cr:YSGG laser and EDTA based conditioning in attachment of fibroblast on root surfaces. This in vitro study was conducted on 81 root plates (6 mm × 4 mm × 1 mm) prepared from 27 single-rooted human mature teeth. The samples were divided into three groups: (1) Er, Cr: YSGG laser conditioning with a G6 tip (2.78 µm, 0.75 W, pulse duration of 140 µs, repetition rate of 20 Hz) for 5-7 s; (2) EDTA conditioning (17%, pH: 8) for 1 min; and (3) the control group which were exposed neither to EDTA nor laser. The viability and proliferation rates assessments were performed using MTT assay on days 3 and 5. In addition, the level of cell attachment was studied using scanning electron microscopy. The data indicated Er, Cr:YSGG conditioning increased cell viability by lapse of time (from days 3-5), with significantly better cell attachment compared to the other groups on days 3 and 5 (P < 0.05). In addition, increasing cell attachment in the EDTA conditioning group compared with the control group was statistically significant on day 5 but not on day 3 (P < 0.05). In conclusion, Er, Cr:YSGG laser conditioning can promote enhance fibroblast attachment on dentinal root surfaces more than EDTA.

Cellular effect of low-level laser therapy on the rate and quality of bone formation in mandibular distraction osteogenesis.

OBJECTIVE: Therapeutic lasers have been shown to influence bone physiology and repair. The aim of the present investigation was to evaluate the use of a GaAlAs (λ:810 nm) laser in distraction osteogenesis. BACKGROUND DATA: To reduce problems associated with distraction osteogenesis and shorten the time required for treatment, it is desirable to accelerate the process of bone formation. MATERIALS AND METHODS: Eighteen male rabbits underwent corticotomy of mandibular body, and customized distraction devices were inserted. After a 5-day latency period, the mandibles were lengthened by 0.5 mm/day for 10 days. The rabbits were divided into two groups. A GaAlAs (λ: 810 nm) laser beam with the parameters power (P), 200 mW; energy density (ED), 3 J/cm(2); time (T), 7.5 sec; power density (PD) 400 mW/cm(2); energy (E) 1.5 J and spot diameter, 0.8 mm was directed medially and laterally in the study group; the control group received no laser treatment. The exposure continued with six more doses every other day. Three rabbits from each of the two groups were euthanized on the 10th, 20th, and 40th days post-distraction (consolidation) period. RESULTS: Both light microscopy and scanning electron microscopic (SEM) analysis showed significant improvement in new bone formation in the study group at the 10th and 20th days compared with the control group, but the difference was more prominent on the 10th day. By the 40th day, there were no significant differences between the two groups. CONCLUSIONS: This study shows that a low-level GaAlAs (λ:810 nm; P, 200 mW) laser hastens new bone formation only in the early stages of the consolidation period in distraction osteogenesis, and has no significant effect in later stages.

Effect of low-level laser therapy irradiation and Bio-Oss graft material on the osteogenesis process in rabbit calvarium defects: a double blind experimental study.

This study aims to assess the effect of low-level laser therapy (LLLT) irradiation and Bio-Oss graft material on the osteogenesis process in the rabbit calvarium defects. Twelve white male New Zealand rabbits were included in this study. Four 8-mm diameter identical defects were prepared on each rabbit's calvarium. One site was left as an untreated control (C), the second site was filled with Bio-Oss (B), the third site was treated with laser irradiation (L), and the fourth site treated with Bio-Oss and laser irradiation (B + L). In the laser group, a diode laser (wavelength 810 nm, output power 300 mW, irradiation mode CW, energy density 4 J/cm2) was applied immediately after surgery and then one other day for the next 20 days. After 4 and 8 weeks, the animals were sacrificed and histological and histomorphometric examinations were performed and the data were subjected to Friedman and repeated measurements ANOVA tests. Significant differences were not found regarding inflammation severity, foreign body reactions, and vitality of newly formed bone on 4th and 8th week after operation. The mean amount of new bone was 15.83 and 18.5% in the controls on the 4th and 8th week; 27.66 and 25.16% in the laser-irradiated group; 35.0 and 41.83% in Bio-Oss and 41.83 and 47.0% in the laser + Bio-Oss treated specimens with significant statistical differences (p <0.05). Application of LLLT in combination with Bio-Oss® can promote bone healing. Therefore, LLLT may be clinically beneficial in promoting bone formation in skeletal defects.

Reconditioning of ceramic orthodontic brackets with an Er,Cr:YSGG laser.

It is now known that erbium lasers are effective in composite removal, but there is minimal information about their efficacy on recycling of ceramic brackets. This study, therefore, aimed to determine the percentage of remaining adhesive on the base and the shear bond strength of debonded ceramic brackets after being reconditioned by an Er,Cr:YSGG (erbium, chromium: yttrium-scandium-gallium-garnet) laser. Thirty premolars were divided into three groups, then bonded with mechanical retention ceramic brackets according to the bracket base conditions: (1) new brackets; (2) debonded brackets cleaned of adhesive with the Er,Cr:YSGG laser at 3.5 W; and (3) debonded brackets cleaned of adhesive with the Er,Cr:YSGG laser at 4 W. Before bonding, the percentage of remaining adhesive on the bases of reconditioned brackets was calculated by using stereomicroscopic images through an image processing software. The brackets were then tested in shear mode in a universal testing machine and the adhesive remnant index scores were determined. The percentage of remaining adhesive on the bases of brackets that were cleaned by the Er,Cr:YSGG laser at 4 W (3.1 %) was significantly lower than that of the 3.5-W laser group (5.9 %) (p = 0.03). No significant difference was found in bond strengths between the new and the reconditioned brackets (p = 0.19). The frequency of bond failure at the enamel-adhesive interface was lower in the laser-reconditioned brackets when compared to the new brackets. The application of Er,Cr:YSGG laser was efficient in removing adhesive from bases of debonded ceramic brackets because it produced comparable bond strengths to new brackets while reducing the risk of enamel damage during debonding.

Er,Cr:YSGG laser influence on microleakage of class V composite resin restorations.

One of the most challenging issues following restoration is microleakage. The aim of this study was to investigate the effects of Er,Cr:YSGG laser with and without acid etching on microleakage of class V composite restorations. A total of 68 human intact premolars were selected, disinfected, and randomly allocated to four experimental groups (n = 16) as well as positive and negative controls (n = 2 each). Dimensionally, similar class V cavities were prepared on buccal surface of each tooth under the following conditions: group 1, bur cavity preparation and chemical etching (BE); group 2, bur cavity preparation and Er,Cr:YSGG laser conditioning (BLc); group 3, Er,Cr:YSGG laser cavity preparation and chemical etching (LE); and group 4, Er,Cr:YSGG laser cavity preparation and Er,Cr:YSGG laser conditioning (LLc). All samples were restored with composite. The teeth were sealed and immersed in 1 % methylene blue for 48 h before being sectioned. The microleakage evaluation was done under a stereomicroscope (×20). The leakage scores were recorded and Kruskal-Wallis and Mann-Whitney tests were used for statistical evaluations. The highest microleakage score was seen in gingival margins of group 4 (LLc) and the lowest in occlusal margins of group 3 (LE). The overall difference in leakage scores among the groups was statistically significant (p < 0.001) with gingival margins showing a significantly higher score than its occlusal counterparts (p < 0.001). It was noted that less microleakage could be achieved when cavities were prepared by laser compared to bur. In addition, less microleakage was seen in acid-etched cavities than laser-conditioned counterparts.

The effect of an Er,Cr:YSGG laser on the micro-shear bond strength of composite to the enamel and dentin of human permanent teeth.

The bond strength of resin composite to Er,Cr:YSGG laser-irradiated enamel and dentin has been evaluated in only a few studies. Therefore, we measured and compared the micro-shear bond strength of composite restorations to enamel and dentin using two different cavity-preparation tools and conditioning methods. One hundred and seventy-five caries-free human third molars were sectioned longitudinally into two different thicknesses and randomly assigned to seven subgroups (n = 25). Enamel groups included laser-cut without etching (LO), laser-cut and laser-etched (LL), laser-cut and acid-etched (LA), bur-cut and laser-etched (BL1), and bur-cut and acid-etched (BA1-comparison group). Dentinal groups included bur-cut and laser-etched (BL2) and bur-cut and acid-etched (BA2-comparison group). The specimens were bonded by Single Bond and Tygon tubes and were restored with Z100 composite. Failure patterns were evaluated using a stereomicroscope, and a shear bond test was performed at 0.5 mm/min. The mean shear bond strength values (MPa) for the LO, LL, LA, BL1 and BA1 enamel groups were 23.14, 23.77, 23.51, 19.30, and 28.99, respectively, whereas for the BL and BA dentinal groups, these values were 22.44 and 26.15, respectively. In enamel specimens, BA1 and LL groups presented the highest shear bond strength values, and the bur-cut and laser-etched (BL1) group showed the lowest values. In the laser-etched groups, bond strength values for bur-cut surfaces were significantly higher than those for laser-cut surfaces. Moreover, there was a significant difference between the BL2 and BA2 dentinal groups. The results of this study indicate that re-etching with acid phosphoric would be recommended if an Er,Cr:YSGG laser is used for tooth preparation or surface treatment.

Treatment of oral squamous cell carcinoma using anti-HER2 immunonanoshells.

BACKGROUND: Worldwide, oral squamous cell carcinoma (potentially mediated by HER2) is recognized as the most commonly occurring malignant neoplasm of the oral cavity. Anti-HER2 nanobodies conjugated to gold-silica nanoshells and used as photothermal treatment for oral squamous cell carcinoma may provide a novel therapeutic alternative to current treatment for this disease. METHODS: KB epithelial or HeLaS3 cell cultures (controls) were exposed to these immunonanoshells, and plasmon resonance electron initiation specific to gold was employed to burn the tumor cells. RESULTS: Following this treatment, significant cell death occurred in the KB tumor cell cultures while there was no evidence of cellular damage or death in the HeLaS3 cell cultures. CONCLUSION: These findings suggest that photothermal treatment of oral squamous cell carcinoma has considerable advantages.

An evaluation of the occluding effects of Er;Cr:YSGG, Nd:YAG, CO2 and diode lasers on dentinal tubules: a scanning electron microscope in vitro study.

OBJECTIVE AND BACKGROUND: Dentin hypersensitivity (DH) is one of the most frequent problems causing patients' complaints following stimulation of cervically exposed dentin. Studies have shown that different lasers have various occluding effects on dentinal tubules. This study is aimed at evaluating the occluding effects of Er;Cr:YSGG (P:0.25W,F:20Hz,Pd:140µS), Nd:YAG (P:1W,F:20Hz), CO(2) (P:1W, Pd:50µs), and 810-nm diode (P:2 W, Pd:30ms) lasers on dentinal tubules. METHODS: Fifteen human third molars were collected and ground-sectioned vertically on the buccal and lingual surfaces to yield two dentin disks of 2-mm thickness. Then, four sites for laser irradiation and one control site were marked in the cervical areas of the dentin disks. Before laser application, specimens were exposed to a 14% EDTA solution to expose dentinal tubules and were then evaluated by scanning electron microscopy (SEM). The tubules' entrance diameters were determined by "scale-bar" software (Phillips Scale-Bar, Phillips, Amsterdam, The Netherlands), which is specifically designed for SEM. The mean diameters for the tubules were then estimated for each site and analyzed statistically. RESULTS: The mean dentinal tubule entrance diameters for Er;Cr:YSGG, 810-nm diode, CO(2), and Nd:YAG, were 1.73, 3.27, 2.10, and 1.64 microns, respectively, compared with 3.52 microns before laser irradiation. Overall, the furthest reduction in mean tubule diameter resulted from the Nd: YAG laser (53%). However, tubular diameter reduction in all laser groups (p<0.05) was found to be statistically significant. In all laser groups, melting of the peritubular dentin was the dominant observed phenomenon. CONCLUSION: Our results indicate that Nd: YAG, Er; Cr: YSGG, and CO(2) lasers, through their ability to melt peritubular dentin, can occlude dentinal tubules partially or totally, and therefore reduce patients' hypersensitivity symptoms. The 810-nm diode laser sealed tubules to a far lesser degree, with negligible effects on desensitization.

Evaluation of the effects of CO2 laser on debonding of orthodontics porcelain brackets vs. the conventional method.

Debonding of ceramic brackets due to their high bond strength and low fracture toughness is one of the clinician's complications. The purpose of this study is to evaluate the effect of a laser on shear bond strength, site of debonding, and ARI index during debonding of ceramic brackets and then compare it to the conventional method used for this procedure. Thirty polycrystalline alumina (G & H Series, Germany) brackets were bonded to 30 intact extracted first and second maxillary premolars and stored in a 1% thymol solution. A chemically cured orthodontic composite resin (No-mix, Unitek, USA) was used for bonding the brackets to the enamel surface on all teeth. All brackets were positioned 4 mm from the incisal edge of the teeth with an orthodontic bracket-positioning device. Then the teeth with bonded brackets were embedded in auto-polymerized polymethylmethacrylate (2.2.3 cm) blocks using a special device to make their slots horizontally parallel. These 30 teeth were then divided into two subgroups: control or no-lased (n = 15) and super pulse CO(2) laser (n = 15). To characterize the peak of SBS in two groups, we used an Instron machine while its blade was moving at a constant speed of 1 mm/min. For evaluating the site of debonding and the adhesive remnant index (ARI index), a light microscope and the Photoshop program were used. Means and standard deviations of the SBS in two subgroups shows that in the control group, the teeth have definitely higher values in comparison to the experimental group. The results of the two groups drew no substantial differences with respect to the surface of debonding, which was mostly within the adhesive. However, observing the results of ARI presented a significant distinction between the control and experimental group. This index denoted that the debonding site in the control group was closer to the enamel adhesive interface and, consequently, the rate of enamel damage in this group would be greater. The present study shows that a CO(2) laser has the potential to replace the conventional method for debonding ceramic brackets due to less debonding force and more adhesive remnant index on the tooth surface.

An in vitro study of root and canal morphology of human deciduous molars in an Iranian population.

Dental caries is the most common chronic childhood disease. Deep caries and dental trauma are the two main etiologic factors responsible for pulp involvement. Better knowledge of the morphology of the root canals of deciduous teeth can improve the outcome of pulp treatment. In this study, 90 deciduous molar teeth (27 first mandibular molars, 27 first maxillary molars, 22 second mandibular molars and 14 second maxillary molars) were prepared using the clearing technique, and then dye was injected into the pulp cavity of each tooth. The roots of the teeth were examined under a stereomicroscope at × 10 magnification from different aspects. Measurements of root length and angulation were also recorded, and the data were analyzed using SPSS-16 software. Deciduous molar teeth in all four classes showed variability in the number of roots and root canals, and also differed in mean root length and angulation. Type I and IV root canal configurations were observed in the samples, and different types of curvature were recorded for the root canals in all four classes. As deciduous molar teeth exhibit morphologic differences from permanent teeth, a thorough knowledge of the root canals in the former can improve the outcome of pulp treatment.