Effects of 970 nm diode laser irradiation on morphology, proliferation, and differentiation of gingival mesenchymal stem cells / Efectos de la irradiación con láser de diodo de 970 m sobre la morfología, la proliferación y la diferenciación de las células madre mesenquimales gingivales

Objective: The objective of this study was to investigate the morphology, proliferation, and differentiation of gingival mesenchymal stem cells (GMSCs) irradiated with a 970 nm Diode Laser (LLLT). It is essential to validate the efficacy of treatment, optimize irradiation conditions and guarantee the safety and quality of stem cells for future use in dental applications. Materials and Methods: GMSCs were cultured in standard conditions and irradiated with a Diode laser (970 nm, 0.5W) with an energy density of 9J/cm2. Cell proliferation was assessed with the WST-1 proliferation kit. GMSCs were differentiated into chondrogenic and osteogenic lineages. Cell morphology was performed with Hematoxylin/eosin staining, and quantitative nuclear analysis was done. Cell viability was monitored with trypan blue testing. Results: GMSCs subjected to irradiation demonstrated a significant increase in proliferation at 72 hours compared to the non-irradiated controls (p=0.027). This indicates that the 970 nm diode laser has a stimulatory effect on the proliferation of GMSCs. LLLT-stimulated GMSCs exhibited the ability to differentiate into chondrogenic and osteogenic lineages. A substantial decrease in cell viability was observed 24 hours after irradiation (p=0.024). However, after 48 hours, the cell viability recovered without any significant differences. This indicates that there might be a temporary negative impact on cell viability immediately following irradiation, but the cells were able to recover and regain their viability over time. Conclusions: This study support that irradiation with a 970 nm diode laser could stimulate the proliferation of GMSCs, maintain their ability to differentiate into chondrogenic and osteogenic lineages, and has minimal impact on the mor- phological characteristics of the cells. These results support the potential use of NIR Lasers in combination with GMSCs as a promising strategy for dental treatments.

Objetivo: El objetivo de este estudio fue investigar la morfología, proliferación y diferenciación de las células madre mesenquimatosas (GMSC) irradiadas con un láser de diodo de 970 nm (LLLT). Es fundamental validar la eficacia del tratamiento, optimizar las condiciones de irradiación y garantizar la seguridad y calidad de las células madre para su uso futuro en aplicaciones dentales.Materiales y Métodos: Las GMSC se cultivaron en condiciones estándar y se irradiaron con un láser de diodo (970 nm, 0,5 W) con una densidad de energía de 9 J/cm2. La proliferación celular se evaluó con el kit de proliferación WST-1. Las GMSC se diferenciaron en linajes condrogénicos y osteogénicos. La morfología celular se realizó con tinción de hematoxilina/eosina y se realizó un análisis nuclear cuantitativo. La viabilidad celular se controló con prueba de azul de tripano. Resultados: Las GMSC sometidas a irradiación demostraron un aumento significativo en la proliferación a las 72 horas en comparación con los controles no irradiados (p=0,027). Esto indica que el láser de diodo de 970 nm tiene un efecto estimulante sobre la proliferación de GMSC. Las GMSC estimuladas con LLLT exhibieron la capacidad de diferenciarse en linajes condrogénicos y osteogénicos. Se observó una disminución sustancial de la viabilidad celular 24 horas después de la irradiación (p=0,024). Sin embargo, después de 48 horas, la viabilidad celular se recuperó sin diferencias significativas. Esto indica que podría haber un impacto negativo temporal en la viabilidad de las células inmediatamente después de la irradiación, pero las células pudieron recuperarse y recuperar su viabilidad con el tiempo. Conclusión: En conclusión, este estudio respalda que la irradiación con un láser de diodo de 970 nm podría estimular la proliferación de GMSC, mantener su capacidad para diferenciarse en linajes condrogénicos y osteogénicos y tiene un impacto mínimo en las características morfológicas de las células. Estos resultados respaldan el uso potencial de láseres NIR en combinación con GMSC como una estrategia prometedora para tratamientos dentales.

Assesment of radiotherapy effects on the blood flow in gingiva and dental pulp - a laser Doppler flowmetry study.

OBJECTIVE: This study aims to determine and compare the dental pulp and gingival blood flow in patients referred for oropharyngeal radiotherapy (RT) at three different time points: before the start, immediately after, and six months following the completion of RT. The aim is also to evaluate the dependence of the pulp and gingival blood flow on the radiation dose. METHODOLOGY: A prospective study included 10 patients referred for intensity-modulated RT (IMRT) in the oropharyngeal region, with at least one intact tooth surrounded by a healthy gingiva. The dose received by each selected tooth and adjacent gingiva was determined according to the map of treatment planning and computer systems. The blood flow measurements were performed using the laser Doppler flowmetry (LDF) method. RESULTS: Comparing vascular flows at three different time points, the median blood flow in the dental pulp showed no statistically significant difference (p=0.325), contrary to gingiva (p=0.011). Immediately after RT completion, the gingival flow significantly increased compared to its starting point (p=0.012). The pulp flow correlated negatively with the radiation dose, whereas a strong correlation was noted 6 months following the RT completion. CONCLUSIONS: RT caused a significant acute gingival blood flow increase, followed by a long-term (over six months) tendency to return to the starting levels. The dental pulp blood flow is differently affected by higher radiation doses (over 50Gy) in comparison to lower doses (below 50Gy). During RT planning, considering the possibility of protecting the teeth localized near the Gross Tumor Volume as a sensitive organ is recommended.

3D-printed individualized tooth-borne tissue retraction devices compared to conventional dental splints for head and neck cancer radiotherapy: a randomized controlled trial.

BACKGROUND: Despite modern treatment techniques, radiotherapy (RT) in patients with head and neck cancer (HNC) may be associated with high rates of acute and late treatment-related toxicity. The most effective approach to reduce sequelae after RT is to avoid as best as possible healthy tissues and organs at risk from the radiation target volume. Even small geometric changes can lead to a significant dose reduction in normal tissue and better treatment tolerability. The major objective of the current study is to investigate 3D printed, tooth-borne tissue retraction devices (TRDs) compared to conventional dental splints for head and neck RT. METHODS: In the current two-arm randomized controlled phase II trial, a maximum of 34 patients with HNC will be enrolled. Patients will receive either TRDs or conventional dental splints (randomization ratio 1:1) for the RT. The definition of the target volume, modality, total dose, fractionation, and imaging guidance is not study-specific. The primary endpoint of the study is the rate of acute radiation-induced oral mucositis after RT. The quality of life, local control and overall survival 12 months after RT are the secondary endpoints. Also, patient-reported outcomes and dental status, as well as RT plan comparisons and robustness analyzes, will be assessed as exploratory endpoints. Finally, mesenchymal stem cells, derived from the patients' gingiva, will be tested in vitro for regenerative and radioprotective properties. DISCUSSION: The preliminary clinical application of TRD showed a high potential for reducing acute and late toxicity of RT in patients with HNC. The current randomized study is the first to prospectively investigate the clinical tolerability and efficacy of TRDs for radiation treatment of head and neck tumors. TRIAL REGISTRATION: ClinicalTrials.gov; NCT04454697; July 1st 2020; https://clinicaltrials.gov/ct2/show/record/NCT04454697 .

Exosome secreted by human gingival fibroblasts in radiation therapy inhibits osteogenic differentiation of bone mesenchymal stem cells by transferring miR-23a.

Radiation-induced fibrosis is recently established as a main reason for osteoradionecrosis of the jaw (ORNJ), anti-eradiation fibrosis drugs achieve satisfactory therapeutic effects. However, the molecular mechanism remain to be fully elucidated. In this study, we found the inhibitory effect of irradiation activated gingival fibroblasts on osteogenic differentiation of human bone mesenchymal stem cells (hBMSCs). Moreover, irradiation-activated-fibroblasts significantly increased miR­23a expression in hBMSCs. Decreased miR­23a enhanced osteogenic differentiation of BMSCs, and elevated miR­23a inhibited this process via directly targeting CXCL12. Finally, exosome released from irradiation-activated-fibroblasts inhibited osteogenic differentiation of BMSCs, and these exosome mediated delivery of miR-23a and further regulated miR-23a/CXCL12 axis in hBMSCs. Therefore, our findings suggest that by transferring miR-23a, exosome secreted by human gingival fibroblasts in radiation therapy serves a vital role in osteogenic differentiation of hBMSCs, which may provide novel clinical treatments for ORNJ.

Photobiomodulation with 808-nm diode laser enhances gingival wound healing by promoting migration of human gingival mesenchymal stem cells via ROS/JNK/NF-κB/MMP-1 pathway.

Photobiomodulation (PBM) has been shown to improve wound healing by promoting mesenchymal stem cell migration and proliferation. However, it remains unknown whether an 808-nm diode laser can influence human gingival mesenchymal stem cells (HGMSCs), and which dose this works well. In the present study, it was found that PBM could promote the migration of HGMSCs but not the proliferation. Furthermore, PBM could activate mitochondrial ROS, which could elevate the phosphorylation levels of JNK and IKB in HGMSCs, and further activate NF-κB as the nuclear translocation of p65 is elevated. Taken together, these present results indicate that PBM might promote cell migration via the ROS/JNK/NF-κB pathway.

Ex Vivo Evaluation of Gingival Ablation with Various Laser Systems and Electroscalpel.

Objective: The aim of this study was to perform a systematic and multifaceted comparison of thermal effects during soft tissue ablation with various lasers and an electroscalpel (ES). Materials and methods: Er:YAG, Er,Cr:YSGG, CO2, Diode, Nd:YAG lasers (1 W, pulsed or continuous wave), an ES, and a scalpel (Sc; control), were employed for porcine gingival tissue ablation. Temperature changes during ablation were measured by using an infrared thermal imaging camera and a thermocouple. After ablations, the wounds were observed using stereomicroscopy and scanning electron microscopy (SEM), and histological sections were analyzed. Compositional analysis was also performed on ablated sites by SEM wavelength dispersive X-ray spectroscopy. Results: The surface temperature during irradiation was highest with CO2 (over 500°C), followed by Diode (267°C) and Nd:YAG (258°C), Er:YAG (164°C), ES (135°C), and Er,Cr:YSGG (85°C). Carbonization was negligible (Er:YAG), slight (Er,Cr:YSGG), moderate (Nd:YAG and ES), and severe (CO2 and Diode). Under SEM observation, Er:YAG and Er,Cr:YSGG showed smooth surfaces but other devices resulted in rough appearances. Histologically, the coagulated and thermally affected layer was extremely minimal (38 µm in thickness) and free from epithelial collapse for Er:YAG. Compared with other devices, less compositional surface change was detected with Er:YAG and Er,Cr:YSGG; additionally, the use of water spray further minimized thermal influence. Conclusions: Among various power devices, Er:YAG laser showed the most efficient and refined gingival ablation with minimal thermal influence on the surrounding tissues. Er:YAG and Er,Cr:YSGG lasers with water spray could be considered as minimally invasive power devices for soft tissue surgery.

Evaluation of Light-Emitting Diodes' Effects on the Expression Level of P53 and EGFR in the Gingival Tissues of Albino Rats.

Background and objectives: The light-curing unit is considered an essential piece of equipment in every dental office. This study was conducted to evaluate the effect of Light-Emitting Diodes (LEDs) by the light cure (LC) device on gingival tissues of albino rats histologically and by regarding the expression of P53 and epidermal growth factor receptor (EGFR). Materials and methods: Gingival tissues of the rats were exposed to LEDs for 30 s with an interval of 30 s for periods of 2 and 5 min and were examined after two and four weeks of light exposure. After the set time, histological sections were studied and the P53 and EGFR expressions were evaluated immunohistochemically and by molecular methods. Results: Mild hyperplasia and mild inflammatory response were detected in higher rates after two weeks of exposure when compared to 4 weeks postexposure. Whereas fibrosis was found at a higher rate after four weeks than that found after two weeks postexposure, parakeratosis was seen only in the group that was exposed for 5 min to LC and when biopsies were taken after 2 weeks. We found that the immunohistochemical expression of P53 was not changed. Similarly, the alteration of EGFR expression was statistically nonsignificant (p > 0.05) when compared to the control group. The data obtained from the qRT-PCR reaction was analyzed using the comparative CT (2-ΔΔCT) method. Statistically, there was no significant difference in the expression of EGER and P53 gene transcripts. Conclusions: LED causes no serious alteration in P53 and EGFR expression, and only trivial histopathological changes occurred, most of which recovered after a 4-week interval.

The Effects of Ultraviolet Light-Emitting Diodes with Different Wavelengths on Periodontopathic Bacteria In Vitro.

Objective: The aim of this study was to examine effects of recently developed ultraviolet light-emitting diodes (UV LEDs) wavelengths on in vitro growth and gene expression of cultural periodontopathic bacteria, and on viability of experimental gingival fibroblasts. Materials and methods: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Streptococcus oralis were irradiated by UV LEDs (265, 285, 310, 365, and 448 nm) at 600 mJ/cm2 and grown anaerobically in vitro. The colony forming units were counted after 1 week. Cell morphology was observed using a scanning electron microscope (SEM). Quantitative real-time polymerase chain reaction was performed to investigate gene expression changes by 310 nm irradiation. Viability of the irradiated human gingival fibroblasts was evaluated using WST-8 assay. Results: Both 265 and 285 nm resulted in the complete death of bacteria and fibroblasts, whereas 310 nm caused partial killing and suppression of bacterial growth and much less damage to the fibroblasts in vitro. Both 365 and 448 nm resulted in no significant change. SEM showed that P. gingivalis cells gradually degraded from day 2 or 3 and were severely destructed on day 5 for 265, 285, and 310 nm. The 310 nm irradiation transiently suppressed the transcripts of SOS response- and cell division-relative genes. Conclusions: Both 265 and 285 nm may induce powerful bactericidal effects and severe fibroblast phototoxicity, and 310 nm may induce partial killing or growth suppression of bacterial cells with much less fibroblast phototoxicity. UV lights may have potential for bacterial suppression, with situations dependent on wavelength, in periodontal and peri-implant therapy.

Exome Sequencing Discloses Ionizing-radiation-induced DNA Variants in the Genome of Human Gingiva Fibroblasts.

Ionizing radiation can induce genomic lesions such as DNA double-strand breaks whose incomplete or faulty repair can result in mutations, which in turn can influence cellular functions and alter the fate of affected cells and organ systems. Ionizing-radiation-induced sequence alterations/mutations occur in a stochastic manner, which contributes to an increased cancer risk in irradiated individuals. Ionizing radiation exposure, and particularly acute doses at high dose rates (as often observed in radiation accidents), induce alterations in the genome that in part will reflect specific characteristics of the DNA damage response and the repair mechanisms involved. Here, the exome of primary human gingival fibroblasts not exposed or exposed to 0.2, 2, 5, or 10 Gy of x rays was investigated after 16 h of DNA repair for ionizing-radiation-induced mutations. The irradiation effect with varying dose was investigated using three different bioinformatic filters for the analysis of accumulated variants per Mb of genomic DNA and per cytogenetic bands. A highly stringent cutoff of 20-fold coverage was used for all analyses. Comparing exome DNA from irradiated and nonirradiated cells disclosed a characteristic variation of the frequency of ionizing-radiation-induced single-nucleotide variants as well as small insertions and deletions among chromosomes and their subregions. Increases in ionizing-radiation-induced variants with increasing dose were highly significant (p = 2.2 × 10, Kruskal-Wallis test). These results indicate that certain chromosomal regions may be more prone to accumulating particular ionizing-radiation-induced alterations than others, which points to a characteristic metasignature in the irradiated exome.

Hemolasertherapy: A Novel Procedure for Gingival Papilla Regeneration-Case Report.

BACKGROUND: Interdental papilla is of major importance to patients' orofacial aesthetics, especially regarding anterior teeth as part of the smile's harmony. Loss of gingival tissue, which constitutes interdental papilla, forms what in odontology is called black spaces. This loss, besides affecting the smile's aesthetics, also provokes phonetic and functional damage. OBJECTIVE: The objective of the authors is to present the result of three clinical cases treated with an innovative technique called hemolasertherapy, which stimulates growth of gingival papilla and thus permanently fills in the black spaces. METHODS: The photobiomodulation therapy (PBMT) used a 660 nm diode laser (Laser Duo, MMO-São Carlos, SP, Brazil), punctual, contact mode in two steps: before the bleeding (first PBMT) and immediately after bleeding (second PBMT). Parameters used were power output: 100 mW, CW; diameter tip: 5 mm; spot area: 0.19 cm2; irradiation exposure time per point: 20 sec; 14 points per daily session; total of 2 sessions, with a 1-week interval; E: 2 J per point; E: per daily session, 28 J; irradiance per point: 0.52 W/cm2; fluence per point: 10.4 J/cm2. Total in two daily sessions: total energy: 56 J; total fluence: 294.75 J/cm, 560 sec total time. An in vitro preliminary study was simultaneously carried out to demonstrate what could happen at cellular level in hemotherapy clinical cases associated with PBMT laser application. RESULTS: This initial study demonstrated that the blood clot originated from the bleeding provoked in the gingival area is rich in mesenchymal stem cells. PBMT enables preservation, viability, and further differentiation, stimulating the return of gingival stem cells, which would support their survival and differentiation in the blood clot, thus favoring interdental papilla regeneration. CONCLUSIONS: Follow-up was done for a time span of 4-5 years and considered excellent with regard to papilla preservation.

Histological and Thermometric Examination of Soft Tissue De-Epithelialization Using Digitally Controlled Er:YAG Laser Handpiece: An Ex Vivo Study.

OBJECTIVE: The purpose of this study was histological and thermometric examination of soft tissue de-epithelialization using digitally controlled laser handpiece (DCLH) - X-Runner. BACKGROUND DATA: Commonly used techniques for de-epithelialization include scalpel, abrasion with diamond bur, or a combination of the two. Despite being simple, inexpensive and effective, these techniques are invasive and may produce unwanted side effects. It is important to look for alternative techniques using novel tools, which are minimally invasive and effective. MATERIALS AND METHODS: 114 porcine samples sized 6 × 6 mm were collected from the attached gingiva (AG) of the alveolar process of the mandible using 15C scalpel blade. The samples were irradiated by means of Er:YAG laser (LightWalker, Fotona, Slovenia), using X-Runner and HO2 handpieces at different parameters; 80, 100, and 140 mJ/20 Hz in time of 6 or 16 sec, respectively. The temperature was measured with a K-type thermocouple. For the histopathological analysis of efficiency of epithelium removal and thermal injury, 3 random samples were de-epithelialized with an HO2 handpiece, and 9 random samples with an X-Runner handpiece with different parameters. For the samples irradiated with DCLH, we have used three different settings, which resulted in removing 1 to 3 layers of the soft tissue. The efficiency of epithelium removal and the rise of temperature were analyzed. RESULTS: DCLH has induced significantly lower temperature increase compared with HO2 at each energy to frequency ratio. The histological examination revealed total epithelium removal when HO2 handpiece was used at 100 and 140 mJ/20 Hz and when DCLH was used for two- and threefold lasing at 80, 100, and 140 mJ/20 Hz. CONCLUSIONS: Er:YAG laser with DCLH handpiece may be an efficient tool in epithelium removal without excessive thermal damage.

Reversal of drug-induced gingival overgrowth by UV-mediated apoptosis of gingival fibroblasts - an in vitro study.

Gingival overgrowth (GO) is an undesirable result of certain drugs like Cyclosporine A (CsA). Histopathology of GO shows hyperplasia of gingival epithelium, expansion of connective tissue with increased collagen, or a combination. Factors such as age, gender, oral hygiene, duration, and dosage also influence onset and severity of GO. One of the mechanisms behind uncontrolled cell proliferation in drug-induced GO is inhibition of apoptotic pathways, with a consequent effect on normal cell turnover. Our objective was to determine if UV photo-treatment would activate apoptosis in the gingival fibroblast component. Human gingival fibroblast cells (HGF-1) were exposed to 200ng/ml or 400ng/ml CsA and maintained for 3, 6, and 9 days, followed by UV radiation for 2, 5, or 10min (N=6). Naïve (no CsA or UV), negative (UV, no CsA), and positive controls (CsA, no UV) were designated. Prior to UV treatment, growth media was replaced with 1M PBS to prevent absorption of UV radiation by serum proteins, and cells were incubated in growth media for 24h post-UV before processing for TUNEL assay, cell proliferation assays, or immunofluorescence. Data showed a temporal increase in proliferation of HGF-1 cells under the influence of CsA. The 200ng/ml dose was more effective in causing over-proliferation. UV treatment for 10min resulted in significant reduction in cell numbers, as evidenced by counts and proliferation assays. Our study is a first step to further evaluate UV-mediated apoptosis as a mechanism to control certain forms of GO.

Effectiveness of laser adjunctive therapy for surgical treatment of gingival recession with flap graft techniques: a systematic review and meta-analysis.

Various flap graft techniques in the treatment of gingival recession have already been reported in the literatures for root coverage. Laser therapy has effects of ablative, hemostatic, and decontamination. Therefore, we performed a meta-analysis of randomized controlled trials (RCTs) to compare the efficacy of flap surgery combined with laser with surgery alone for treating gingival recession. The studies were searched from PubMed, Embase, Web of science, and the Cochrane Central Register of Controlled Trials by two reviewers up to August 2017. The quality of RCTs was assessed by Cochrane Handbook. Data were extracted from studies and analyzed by Review Manager 5.3. 95% confidence interval (CI) and risk ratio (RR) were calculated for dichotomous data. Seven RCTs with 173 patients and 296 teeth were included in the meta-analysis. We found no statistically significant differences between two groups in GRD (gingival recession depth) (P = 0.21), GRW (gingival recession width) (P = 0.92), RES (root esthetic score) (P = 0.21), and CRC (complete root coverage) (P = 0.09). Statistically significant differences were found between two groups in the WKT (width of keratinized tissue) (P < 0.0001) and 1-year follow-up of PD (probing depth) (P = 0.03) and CAL (clinical attachment level) (P < 0.00001). The meta-analysis found that surgery with laser therapy provided clinical advantages in terms of WKT and 1-year follow-up of PD and CAL. However, flap graft associated with laser did not offer additional benefit to root coverage and esthetics in treating gingival recession. More long-term studies are required to assess these parameters.

Gingival depigmentation using Er:YAG laser and scalpel technique: A six-month prospective clinical study.

OBJECTIVE: To compare the 6-month clinical efficacy of Er:YAG laser and standard scalpel technique in treating gingival hyperpigmentation. METHOD AND MATERIALS: Patients requesting treatment for moderate to severe gingival hyperpigmentation in the maxilla were enrolled in this split-mouth study. The contralateral maxillary sides were randomly assigned to receive either Er:YAG laser (continuous wavelength of 2,940 nm) with a noncontact tip or the standard scalpel technique. Dummett oral pigmentation index (DOPI) and Hedin melanin index (HMI) were compared at the baseline and at 1 and 2 weeks, and 1, 3, and 6 months following the treatment. Bleeding Index, total treatment time, patient preference, pain perception at the first 3 days, wound healing, and level of satisfaction were also compared. Mann-Whitney test, Kruskal-Wallis test, and chi-square test were used to test the significance between variables. A P value of less than or equal to .05 was considered statistically significant. RESULTS: Of the 22 patients enrolled, 20 completed this study. After assessing DOPI and HMI at 1 and 2 weeks, and at 1-, 3-, and 6-month follow-up appointments, both Er:YAG laser and scalpel were significantly effective in treating gingival hyperpigmentation when compared to baseline (P < .001) but with no statistically significant difference between the two treatment methods (P > .05). More patients preferred the scalpel technique as it was associated with slightly shorter treatment time and less postoperative pain when compared to Er:YAG laser, but with no statistical significance (P > .05). Er:YAG laser sites showed minimal bleeding and more rapid wound healing (P < .001). CONCLUSION: Both Er:YAG laser and scalpel technique achieved similar outcomes regarding the efficacy of gingival depigmentation, postoperative pain perception, and the time required for the treatment. Laser therapy requires more advanced technology and is associated with higher financial costs. Therefore, the scalpel technique is still considered the gold standard treatment for gingival depigmentation.

Analysis of temperature increase in swine gingiva after exposure to a Polywave® LED light curing unit.

OBJECTIVE: This study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave® LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). METHODS: After local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n=10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni's post-hoc test (α=5%). A binary logistic regression analysis determined the risk of gingival lesion development. RESULTS: Without RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p=0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. SIGNIFICANCE: Exposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD.

Role of the adjunctive antimicrobial photodynamic therapy to periodontal treatment at plasmatic oxidative stress and vascular behavior.

BACKGROUND: To evaluate for the first time in vivo the effects of methylene blue (MB) photosensitizer dissolved in ethanol in antimicrobial photodynamic therapy (aPDT) as adjuvant periodontal treatment, at plasmatic oxidative stress and vascular behavior in rat model. METHODS: Wistar rats were divided into negative control (NC, no periodontitis) and positive control (PC, with periodontitis, without any treatment). The other groups had periodontitis and were treated with scaling and root planing (SRP); SRP+aPDT+MB dissolved in water (aPDT I); SRP+aPDT+MB dissolved in ethanol (aPDT II). The periodontitis was induced by ligature at the mandibular right first molar. At 7/15/30days, rats were euthanized, the plasma was used to determine oxidative stress parameters and gingival tissue for histomorphometric analysis. RESULTS: PC showed higher thiobarbituric acid reactive substances levels in 7/15/30days. aPDT II was able to block the lipid peroxidation, especially between 15th and 30th days. Glutathione reduced levels were consumed in PC, aPDT I and II groups throughout the experiment. aPDT II increased the vitamin C levels which were restored in this group in the 30th day. aPDT II group showed the highest number of blood vessels. CONCLUSION: In summary, the aPDT with MB dissolved in ethanol provides better therapeutic responses in periodontitis treatment.

Efficacy of surgical laser therapy in the management of oral pigmented lesions: A systematic review.

BACKGROUND: Oral pigmentation, especially in the gingiva poses esthetic problems. Laser therapy has been widely used for cosmetic therapy in dentistry. The aim of the present study was to systematically review the efficacy of surgical laser therapy (SLT) in the management of oral pigmented lesions (OPL). MATERIALS AND METHODS: The addressed focused question was "Is SLT effective in the management of OPL?" Databases (MEDLINE via PubMed; EMBASE; Cochrane Central Register of Controlled Trials and Cochrane Oral Health Group Trials Register databases) were searched from 1970 up to and including February 2017. RESULTS: Ten studies were included. The reported number of OPL ranged between 8 and 140. Oral pigmented sites included, gingiva, buccal and labial mucosa, alveolar mucosa and lips. Lasers used in the studies included Q-switched alexandrite, Neodymium-doped yttrium aluminium garnet, diode, Erbium: yttrium aluminium garnet and carbon dioxide laser. Laser wavelength, power output and number of irradiations were 635-10,600nm, 1-10W and 1 to 9 times, respectively. The follow up period ranged from 6 to 24months. All studies reported SLT to be effective in the treatment of OPL. In five studies, recurrence of OPL occurred which ranged from 21.4% to 45%. CONCLUSIONS: Lasers are effective in the management of OPL including physiologic gingival pigmentation, smokers' melanosis and pigmentation in Laugier-Hunziker syndrome. Different laser types (CO2, Er:YAG and Diode) showed comparable outcomes in the treatment of OPL.

Effects of two wattages of low-level laser therapy on orthodontic tooth movement.

INTRODUCTION: Mixed outcomes have been found in animal and clinical studies with regard to the use of low-level laser therapy (LLLT) as a modality to accelerate orthodontic tooth movement (OTM). One major reason for the variable findings is the different methodologies and protocols for laser therapy use. OBJECTIVE: The aim of this study was to determine whether orthodontically moved molars exposed to two different wattages at the same energy density of LLLT exhibited differences in the amount of tooth movement and molecular and histological changes in the adjacent periodontal areas. METHODS: An orthodontic force was applied to rat upper first molars exposed to 500mW (EX-500) and 1000mW (EX-1000) of laser application, with a control group (CT) with no laser application. Gene expression in the periodontal ligament (PDL) and histology of the palatal gingiva of the molars were analyzed. RESULTS: There was a statistically significant difference for OTM between EX-500 but not between EX-1000 and CT groups. RANKL and MMP-13 expression levels in the PDL of orthodontically moved molars, however, were increased significantly in laser-exposed groups compared to CT. Early signs of dysplasia were observed in over half of the animals in the EX-1000 group. CONCLUSIONS: Our results provide evidence for molecular changes and the potential dysplastic effects of laser on the surrounding soft tissues. Further studies are needed to better identify an optimum laser protocol to maximize the desired effect.

Cytogenetic biomonitoring in individuals exposed to cone beam CT: comparison among exfoliated buccal mucosa cells, cells of tongue and epithelial gingival cells.

OBJECTIVES: To evaluate chromosomal damage and cytotoxicity in exfoliated buccal mucosa cells, cells of the tongue and epithelial gingival cells from adults following CBCT scan and to compare the sensitivity of the different exfoliated cells to a same dosage of ionizing radiation. METHODS: The study included 46 healthy participants (median age 27 years; age range 23-42 years) who had a CBCT scan. Exfoliated mucosa cells were collected immediately before the CBCT scan and 10 days after. Cells were centrifuged, fixed in the fluid of methanol : glacial acetic acid (3 : 1) and stained using the method of Schiff's reagent and fast green. One observer analyzed all the slides. For interobserver variances, a second observer scored 16 slides chosen from all the subjects. The same set of 16 slides were analyzed once again a month later for intraobserver variances. RESULTS: There is no significant differences for micronucleated cells before and after a CBCT scan in exfoliated buccal mucosa cells (p = 0.476), cells of the tongue (p = 0.884) and epithelial gingival cells (p = 0.362). The frequencies of pyknosis cell and karyolysis cell had significantly increased after CBCT scan in the three groups. No significant difference was found among the three kinds of mucosa cells (p = 0.557). The interobserver (p = 0.624) and intraobserver (p = 0.193) variances were not significant. CONCLUSIONS: A CBCT scan may induce cytotoxicity but not chromosomal damage in the oral mucosa cells, including buccal mucosa cells, cells of the tongue or epithelial gingival cells. The sensitivity of the different exfoliated cells to the same dosage of radiation had no statistically significant difference.