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Objective: The present study aimed to evaluate the effectiveness of the application of photobiomodulation therapy (PBMT) in the prevention of recurrent herpes labialis (RHL) through a randomized controlled clinical trial. Background data: RHL is a lifelong infection that effects patients' quality of life. In the literature PBMT has shown positive results preventing RHL, decreasing recurrences and severity of lesions. Despite the good results reported, there are still few controlled clinical studies published on the subject. Methods: For this study, 158 volunteers were recruited and were randomly divided into three study groups: Laser 1-1 J/point (L1J): n = 61, Laser 2-2 J/point (L2J): n = 50, and placebo-0 J/point: n = 47. The treatment consisted of a protocol of 15 sessions throughout 6 months and 2 years of follow-up posttreatment. Results: The results showed that L1J presented the most satisfactory results concerning the reduction of the number of lesions per year and less severity of recurrences in the long-term evaluation when compared with L2J. Both Laser Groups (L1J and L2J) were statistically more efficient than placebo in all aspects analyzed. All patients who received laser treatment (L1J and L2J) and presented recurrences had significant improvement in frequency and/or severity of lesions. No patient had side effects from treatment. Conclusions: PBMT can be effective in the reduction of the frequency of recurrences of RHL and in the severity of postirradiation lesions that may appear.

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OBJECTIVES: This randomized controlled trial aimed to evaluate different protocols for dentin hypersensitivity treatment with low-power lasers and desensitizing agents, and the association between low-power lasers and desensitizing agents. MATERIALS AND METHODS: Fifty-four patients (303 teeth) were randomly allocated to three groups: G1, 3% nitrate potassium gel, UltraEZ (n = 17); G2, photobiomodulation therapy (PBM) with a low-level infrared laser (n = 17), 100 mW, spot size of 0.028 cm2, and dose of 1 J per point; and G3, nitrate potassium + PBM (n = 20). Treatments were applied to the buccal cervical region at intervals of 72 h, and all protocols were performed in three sessions. The patients' response to evaporative stimuli was rated using the visual analog scale (VAS). Re-evaluations were performed immediately after each application and 1 week, 1 month, and 3 months after treatment. A two-way repeated measures test and Tukey's post hoc test were used for multiple comparisons (α = 5%). RESULTS: There was a reduction in pain levels at the end of treatment in all groups. There were no significant differences in VAS score changes between the groups immediately after treatment and after the third month, compared to the baseline (p > 0.05). CONCLUSION: Under the limitations of this in vivo study, the proposed three-session protocol was effective in reducing dentin hypersensitivity after 3 months, regardless of the desensitization mechanism used. Conservative and long-term protocols are interesting for the control of pain caused by dentin hypersensitivity. CLINICAL RELEVANCE: The increase in cervical dentin hypersensitivity prevalence warrants easy-to-apply and long-lasting desensitizing protocols for pain control.

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OBJECTIVES: To evaluate the effect of Nd:YAG laser irradiation as a prior desensitizing strategy on immediate and medium-term microtensile bond strength (µTBS) to simulated hypersensitive dentin. MATERIALS AND METHODS: Flat mid-coronal dentin was obtained from third molars and submitted to a 600-grit SiC paper (1 min; N: normal dentin) or subsequently challenged with citric acid (6%, 1 min; H: simulated hypersensitive dentin). Afterwards, dentin was or was not (C: control; HC, NC - each n = 7) irradiated with Nd:YAG laser (L: laser; 1.0 W/10 Hz/100 mJ/4 irradiations of 50-60 s; HL, NL - each n = 7). A 2-step self-etch adhesive (Clearfil SE Bond) was applied and composite (Filtek Z350) buildups were constructed. After 24-h (distilled water/37 °C) storage, specimens were sectioned into beams and tested (µTBS; 0.5 mm/min) immediately or after 6-month aging. Three-way ANOVA and Tukey tests were applied (α = 0.05). Qualitative evaluation of the adhesive interface (n = 1 extra tooth per group) was performed by Confocal Laser Scanning Microscopy. RESULTS: Substrate condition (p < 0.001), laser irradiation (p < 0.001), and aging (p = 0.002) influenced the results. Furthermore, there was interaction between substrate and irradiation (p < 0.001). Laser irradiation favored µTBS exclusively to hypersensitive dentin immediately and after aging. µTBS to hypersensitive dentin was higher than that to the normal substrate only when it was laser-irradiated. In any case, immediate µTBS was always higher than that after aging. CLSM revealed longer and more numerous resin tags for simulated hypersensitive dentin, and shorter and fewer resin tags for laser-irradiated dentin. No differences were observed in the hybrid layer itself. CONCLUSION: Nd:YAG laser irradiation prior to restoration favored the µTBS of a self-etch adhesive and resin composite to hypersensitive dentin. CLINICAL RELEVANCE: Desensitizing strategies are usually tried before performing restorative treatments in hypersensitive dentin; therefore, they may influence behavior of the adhesive interface established. However, instead of causing concern, Nd:YAG laser irradiation revealed a favorable effect on the aforementioned interface.

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Oral leukoplakia is a potentially malignant disorder, defined as a white plaque that cannot be diagnosed as another known disease or disorder, and has an increased risk of malignancy. The aim of the present study was to evaluate the results of CO2 laser treatment in a well-defined cohort of patients with oral leukoplakia in order to identify the occurrence of clinical outcomes of relapse, resolution, or malignancy after treatment. The study group comprised 37 patients. Before treatment, clinical photographs and incisional biopsies were obtained in all cases. In addition, the post-treatment results were documented using photographs. Evaluation of treatment results was performed by an independent researcher who had not performed the surgery. The minimum, maximum, and mean values of continuous variables were calculated. Statistically significant relationships were tested using the Cox regression analysis. A survival curve was constructed according to the Kaplan-Meier method to analyze the malignant transformation and recurrence of oral leukoplakia. The clinical outcomes analyzed were resolution, recurrence, and malignancy. The mean follow-up period was 36 months (range, 6-239 months). In 13/37 patients, leukoplakia recurred between 6 and 93 months (mean, 38.2 months). In 8/37 patients, a malignant transformation occurred (mean, 50.6 months). In 16/37 patients, lesion resolution occurred. No risk factor was statistically significant for malignancy or recurrence of lesions. The treatment of the lesions by CO2 laser was efficient in the removal of the lesions; however, it did not avoid the clinical outcomes of recurrence or malignancy.

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BACKGROUND: Dentin hypersensitivity (DH) is a common problem in the population that can have a significant impact on the quality of life of those who suffer from the condition. OBJECTIVES: Compare the efficacy of two treatments for DH: Ca/PO4 - /F- varnish (Clinpro White Varnish) and ionomeric sealant (IS) (Clinpro XT Varnish) with a placebo. METHODS: Participants (121) with at least one tooth with visual analogue scale (VAS) score of 4 and above were randomly and blindly allocated to the groups. Treatments were performed by a trained researcher. DH was evaluated by another blind researcher after the treatment and after 1 week, 4 weeks, 3 months and 6 months. After 4 weeks, placebo received the DH treatment with IS; thus, the participants were not assessed after 3 and 6 months. Primary outcome was DH reduction after 4 weeks. Differences in VAS scores in the other time intervals and entire values of VAS were considered secondary outcomes. Comparisons were made among the groups (α = 0.05). RESULTS: IS showed the highest VAS value difference between baseline and 4 weeks (mean ± SD: 3.7 ± 2.2), differing significantly from placebo (2.3 ± 1.7) and Ca/PO4/F- varnish (2.6 ± 2.0). Ca/PO4- /F- varnish did not differ from placebo. In all time intervals, VAS values of all groups were significantly lower than the baseline value, without differences among groups. For the long-term differences in VAS values (3 and 6 months), the IS exhibited significantly higher values than Ca/PO4- /F- varnish. CONCLUSIONS: The IS was the most efficacious product for reducing DH, whereas Ca/PO4- /F- varnish did not differ from placebo. Registered in ClinicalTrials.gov (NCT04591444).

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OBJECTIVES: Although ultra-short pulsed laser (USPL) microstructuring has previously improved zirconia bond-strength, it is yet unclear how different laser-machined surface microstructures and patterns may influence the material's mechanical properties. Therefore, the aim of this study was to assess the flexural strength of zirconia after different USPL settings creating three different geometrical patterns with structures in micrometer scale. METHODS: One hundred sixty zirconia bars (3Y-TZP, 21 × 4 × 2.1 mm) were prepared and randomly divided into five groups (n = 32): no surface treatment (negative control-NC); sandblasting with Al2O3 (SB); and three laser groups irradiated with USPL (Nd:YVO4/1064 nm/2-34 J/cm2/12 ps): crossed-lines (LC), random-hatching (LR), and parallel-waves (LW). Bars were subjected to a four-point flexural test (1 mm/min) and crystal phase content changes were identified by X-ray diffraction. Surface roughness and topography were analyzed through 3D-laser-profilometry and SEM. Data were analyzed with parametric tests for roughness and Weibull for flexural strength (α = 5%). RESULTS: LR (Mean[95%CI]: 852.0 MPa, [809.2-894.7]) was the only group that did not show a significantly different flexural strength than NC (819.8 MPa, [796.6-842.9]), (p > 0.05). All laser groups exhibited higher Weibull moduli than NC and SB, indicating higher reliability and homogeneity of the strength data. An increase of monoclinic phase peak was only observed for SB. CONCLUSION: In conclusion, USPL created predictable, homogeneous, highly reproducible, and accurate surface microstructures on zirconia ceramic. The laser-settings of random-hatching (12 ps pulses) increased 3Y-TZP average surface roughness similarly to SB, while not causing deleterious crystal phase transformation or loss of flexural strength of the material. Furthermore, it has increased the Weibull modulus and consequently material's reliability. CLINICAL SIGNIFICANCE: Picosecond laser microstructuring (LR conditions) of 3Y-TZP ceramic does not decrease its flexural strength, while increasing materials realiability and creating highly reproducible and accurate microstructures. These features may be of interest both for improving clinical survival of zirconia restorations as well as enhancing longevity of zirconia implants.

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Abstract Oral leukoplakia is a potentially malignant disorder, defined as a white plaque that cannot be diagnosed as another known disease or disorder, and has an increased risk of malignancy. The aim of the present study was to evaluate the results of CO2 laser treatment in a well-defined cohort of patients with oral leukoplakia in order to identify the occurrence of clinical outcomes of relapse, resolution, or malignancy after treatment. The study group comprised 37 patients. Before treatment, clinical photographs and incisional biopsies were obtained in all cases. In addition, the post-treatment results were documented using photographs. Evaluation of treatment results was performed by an independent researcher who had not performed the surgery. The minimum, maximum, and mean values of continuous variables were calculated. Statistically significant relationships were tested using the Cox regression analysis. A survival curve was constructed according to the Kaplan-Meier method to analyze the malignant transformation and recurrence of oral leukoplakia. The clinical outcomes analyzed were resolution, recurrence, and malignancy. The mean follow-up period was 36 months (range, 6-239 months). In 13/37 patients, leukoplakia recurred between 6 and 93 months (mean, 38.2 months). In 8/37 patients, a malignant transformation occurred (mean, 50.6 months). In 16/37 patients, lesion resolution occurred. No risk factor was statistically significant for malignancy or recurrence of lesions. The treatment of the lesions by CO2 laser was efficient in the removal of the lesions; however, it did not avoid the clinical outcomes of recurrence or malignancy.

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The ultrastructural and mechanical properties of enamel surface were evaluated after prolonged bleaching treatments with 10% carbamide peroxide in the presence or absence of orange juice (erosive challenge) and toothbrushing (abrasive challenge). In total, 145 incisor bovine teeth were used in this study. Twenty-five samples were prepared for the ultrastructural evaluations, and 120 samples were prepared for microhardness and roughness tests. These 120 samples were divided into eight experimental groups (n = 15): G1- artificial saliva; G2- abrasion; G3- erosion; G4- dental bleaching; G5- erosion + abrasion; G6- bleaching + abrasion; G7- bleaching + erosion; and G8- bleaching + erosion + abrasion. All groups were tested at T0 (before treatment), T1 (14 days), T2 (21 days), and T3 (28 days). Two-way analysis of variance for repeated measures and the post hoc Sidak tests (p ≤ 0.05) were used. The roughness evaluation demonstrated an increase in damage for all experimental groups with an increase in the time period. For microhardness, the groups exposed to artificial saliva (AS) and abrasive challenge did not show any differences at any time points, while the other groups showed a decrease in microhardness from T0 to T3. Ultrastructural evaluation showed different surface alterations in response to the treatments. Despite prolonged bleaching periods, the procedure caused lesser enamel surface alterations than exposure to orange juice alone or in combination with brushing.

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OBJECTIVE: To evaluate the effect of charcoal-based dentifrices on the color change (CC) and surface wear (SW) of resin composites. MATERIALS AND METHODS: Five dentifrices, including three toothpastes: Colgate total-12 (C12), Black is the new White (CPX), and Natural (NAT); and two powders: Carvvo (CVV) and Whitemax (WMX), were evaluated. Composite blocks (5x5x2mm- Z350 3 M/ESPE, shade A2) were subjected to 417 and 5004 brushing cycles. The CC (n = 7, CIEDE2000; ΔE00 ) was evaluated using a spectrophotometer. SW (n = 5) was assessed using profilometry. The dentifrice particles were characterized by scanning electron microscopy (SEM). RESULTS: In 417 brushing cycles, resin composite exhibited higher color change upon being exposed to NAT, CVV and WMC than to C12 (p ≤ 0.05). In 5004 brushing cycles, resin composite showed higher color change values when exposed to all dentifrices, except C12 (p ≤ 0.05). The powders promoted higher SW on resin composite than C12 in both evaluation times (p ≤ 0.05). In 417 cycles, WMX caused higher SW on composite than C12, CPX, and NAT (p ≤ 0.05). No significant different SW was found between powders and charcoal-based toothpastes after 5004 brushing cycles (p > 0.05). SEM showed larger particles for powder than for toothpaste dentifrices. CONCLUSION: Within the limitations of this study, both null hypotheses have been rejected. Resin composites exposed to charcoal-based dentifrices exhibited significantly (p ≤ 0.05) higher color change and surface wear than conventional toothpastes. CLINICAL SIGNIFICANCE: Color change and surface wear shown by charcoal dentifrices may compromise the longevity of restorations.

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OBJECTIVE: This five-phase, single-blind, crossover in situ trial evaluated the effects of desensitizing or anti-erosive toothpastes on dentin erosive wear and tubule occlusion. MATERIALS AND METHODS: Some characteristics such as relative dentin abrasivity (RDA), viscosity (V), cytotoxicity, and fluoride and calcium (Ca) availability of the toothpastes were also tested. Samples were positioned on removable intraoral appliances from 15 volunteers (n=4), according to the groups, C-control (0 ppm fluoride), F-sodium monofluorophosphate (MFP), A-MFP and arginine+calcium carbonate, CSP-calcium sodium phosphosilicate, and CS-MFP and calcium silicate+sodium phosphate. Erosion-abrasion cycling was performed (1% citric acid, 2min, 6×/day; toothbrushing, 5s, 2×/day). Surface loss (SL) was evaluated by optical profilometry. Environmental scanning electron microscopy images (ESEM) counted the number of open dentin tubules (ODTs). Data were statistically analyzed (α=0.05). RESULTS: There were no significant differences in SL among groups (p=0.468). The ODT for CSP, CS, and A groups were significantly lower than the control. CSP and CS presented significantly less ODT than F, but they did not significantly differ from A. F and CS were more abrasive than all the other toothpastes; CSP was more abrasive than A, and C was the least abrasive. CSP presented higher V (p<0.05). All toothpastes presented lower cell viability than the control without toothpaste exposure. F and A presented significantly higher values of F- (p<0.05). All fluoride toothpastes had similar amount of Ca, differing from the control (p<0.05). CONCLUSION: Although the toothpastes caused similar degree of erosive wear, CSP and CS were able to occlude the dentin tubules. CLINICAL RELEVANCE: Desensitizing toothpastes containing calcium, sodium, phosphate, and silicate could be a suitable option for treating dentin hypersensitivity.

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