Evaluation of chemical and morphological changes in radicular dentin after different final surface treatments.

The aim of this study was to evaluate the chemical and morphological effects of different lasers as a final surface treatment for endodontic therapy through energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Twenty-five maxillary canines were selected and instrumented with K3 system. Roots were randomly distributed into five groups (n = 5) according to the surface treatment: GI (distilled water), GII (NaOCl + EDTA), GIII (NaOCl + EDTA + 980 nm diode laser), GIV (NaOCl + EDTA+ 1,064 nm Nd:YAG laser), and GV (NaOCl + EDTA+ 2,780 nm Er, Cr:YSGG laser). Lasers were applied for 20 s and samples were bisected, exposing the treated surface and then subjected to elements quantification by EDS and morphological evaluation by scanning electron microscope (SEM). EDS data were submitted to ANOVA-two way, and SEM scores were submitted to two-way Kruskal-Wallis and Dunn's tests. The EDS analysis showed no difference for the chemical elements and Ca/P ratio between groups (p > .05). Statistical analysis showed more intense results for GV and less intense results for GI (p < .05). The GIII showed an amorphous organic matrix surface, while GV provided greater removal of intertubular dentin forming craters, and GIV promoted dentin fusion. The EDS method used in this study was not able to verify any chemical changes in root canal dentin; Nd:YAG, Er, Cr:YSGG, and 980 nm diode laser were capable of modifying the dentin morphology, correlating characteristics features for each one, which are essential clinical knowledge to establish the correct indication for each case. RESEARCH HIGHLIGHTS: EDS was not able to verify any chemical changes in root canal dentin after 980 nm diode, Nd:YAG and Er;Cr:YSGG laser treatments Nd:YAG, Er, Cr:YSGG, and 980 nm diode laser modified dentin morphology, correlating characteristics features for each one.

Low-level laser therapy increases interleukin-1ß in gingival crevicular fluid and enhances the rate of orthodontic tooth movement.

INTRODUCTION: The aim of this investigation was to evaluate the effects of low-level laser therapy on interleukin-1ß (IL-1ß) levels in gingival crevicular fluid and its correlation with orthodontic tooth movement. METHODS: A split-mouth design was used in 10 subjects (6 female, 4 male) aged 14 to 25 years, whose maxillary first premolars were extracted. A gallium-aluminum-arsenide semiconductor diode laser (wavelength, 940 nm; energy density, 8 J/cm2; power output, 100 mW) delivered low-level laser therapy to the experimental canine undergoing distalization at 10 points. The control canine was distalized without low-level laser therapy. The experimental and control canines were distalized using a force of 150 g provided by nickel-titanium closed-coil springs. Gingival crevicular fluid was collected at 5 time points from the control and experimental sides, and the levels of IL-1ß were analyzed by enzyme-linked immuno-sorbent assay (ELISA). The distal movements of the maxillary canines were measured and compared. RESULTS: Increased levels of IL-1ß were observed in the experimental canines compared with the control canines (P <0.001). Cumulative tooth movements over an 8-week experimental period were greater for the experimental canines (occlusogram and software, 4.450 and 4.4903 mm, respectively) compared with the control canines (occlusogram and software, 2.025 and 2.0501 mm, respectively). A positive correlation existed between the IL-1ß levels and the amounts of tooth movement across all time intervals. CONCLUSIONS: In combination with light orthodontic force, application of low-level laser therapy increased the levels of IL-1ß in gingival crevicular fluid and accelerated orthodontic tooth movement.

The effect of low-level laser therapy on tooth movement during canine distalization.

The aim of the study is to determine the effects of low level laser therapy on tooth movement during canine distalization by evaluating IL-1ß, TGF-ß1 levels in gingival crevicular fluid. Maxillary first premolars of the 15 Angle Class II division I patients (12-19 years old) were extracted. Right maxillary canines were distalized by standard protocol as control group whereas the left maxillary canines distalized by laser application. A gallium-aluminum-arsenide diode laser with an output power of 20 mW was applied as five doses from the buccal and the palatal side on the day 0, and the 3rd, 7th, 14th, 21th 30th, 33st, 37th, 60th, 63th, and 67th days. Gingival crevicular fluid samples were obtained with filtration paper at the initial, 7th, 14th, and 21th days, and the IL-1ß and TGF-ß1 cytokine levels were analyzed. Orthodontic models and periodontal indices were taken initially and on the days 30th, 60th, and 90th of canine distalization period. Tooth movement was assessed by scanning models (3Shape). The amount of tooth movement in the laser group was 40% more than the control group. First day IL-1ß levels were statistically higher than initial and 21st day levels (P= 0.003, P = 0.012). The rise in IL-1ß levels caused the negative correlations between 7th day IL-1ß and 21st day TGF-ß1 levels describes the tissue effects of laser application. Periodontal indices showed no sign of gingival inflammation during canine distalization period. As conclusion, laser does accelerate tooth movement and could shorten the whole treatment duration.

Effects of different lasers on organic/inorganic ratio of radicular dentin.

The aim of this study was to evaluate the chemical stability of endodontic-treated root dentin after different laser irradiations through Raman spectroscopy. Fifty maxillary canines were selected and prepared with K3 system. Roots were randomly distributed into five groups (n = 10) according to the surface treatment: GI (water), GII (NaOCl + EDTA), GIII (NaOCl + EDTA + 980 nm Diode laser), GIV (NaOCl + EDTA+ 1064 nm Nd: YAG laser) and GV (NaOCl + EDTA+ 2780 nm Er,Cr: YSGG laser). Lasers were applied for 20 s. Samples were bisected, and the organic and inorganic content of dentin was analyzed by Raman spectroscopy. Data were submitted to ANOVA and Tukey tests (p < 0.05). None of the surface treatments alter the inorganic content (cts) (p = 0.183). Roots irradiated with Er,Cr: YSGG laser had a reduced collagen content (GV-290.7 ± 41.7) compared with the water-treated roots (GI-328.3 ± 63.5) and those treated with NaOCl + EDTA (GII-333.9 ± 55.8). Roots irradiated with Er,Cr: YSGG laser also showed a higher inorganic/organic ratio (GV-9.5 ± 1.1) than roots treated with water (GI-7.7 ± 1.5), NaOCl + EDTA (GII-8.0 ± 1.4) and diode laser (GIII-8.2 ± 1.6). Both organic and inorganic contents increased from cervical to apical thirds in all groups. None of the surface treatments were able to promote changes in the inorganic content of the root dentin; treatment with NaOCl + EDTA combined with Er,Cr: YSGG altered collagen.

Impact of extracorporeal shockwave therapy on tooth mobility in adult orthodontic patients: a randomized single-center placebo-controlled clinical trial.

AIM: This RCT investigated the effect of non-invasive extracorporeal shockwaves on tooth mobility in orthodontic patients after active treatment. MATERIALS AND METHODS: Seventy-two adult patients were included in the study. Immediately after active orthodontic treatment, patients were assigned to a treatment or a placebo group based on block randomization. The orthodontic patients were required to be otherwise healthy. The region of interest was the anterior portion of the mandible. The treatment group received a single shockwave treatment with 1000 impulses while the placebo group was treated with an acoustic sham. Tooth mobility was evaluated over a period of 6 months using a Periotest and manual testing. Pocket probing depths, bleeding on probing and the irregularity index were also assessed. RESULTS: Tooth mobility reduced significantly over 6 months in both groups, but shockwaves achieved significantly more rapid reduction on manual testing. Probing depth was significantly reduced while the irregularity index remained stable. Bleeding on probing was significantly reduced in the treatment group. No anti-inflammatory effect could be derived due to possible initial group differences. CONCLUSIONS: The mobility of teeth aligned by orthodontic treatment reduces over time. Shockwave treatment appeared to reduce tooth mobility more rapidly.

Connective tissue graft associated or not with low laser therapy to treat gingival recession: randomized clinical trial.

BACKGROUND: To evaluate the treatment of gingival recession with a connective tissue graft (CTG) alone or in combination with low-level laser therapy (CTG + L). METHODS: Forty patients presenting 40 Miller Class I and II gingival recessions were included. The defects were randomly assigned to receive either CTG (n = 20) or CTG + L (n = 20). A diode laser (660 nm) was applied to the test sites immediately after surgery and every other day for 7 days (eight applications). RESULTS: The mean percentage of root coverage was 91.9% for the test group and 89.48% for the control group after 6 months (p > 0.05). The test group presented more complete root coverage (n = 13, 65%) than the control group (n = 7, 35%) (p = 0.04). Dentine sensitivity decreased significantly after 6 months in both groups (p < 0.001). The two groups showed improvement in aesthetics at the end of treatment. CONCLUSIONS: Low-level laser therapy may increase the percentage of complete root coverage when associated with CTG.

Influência do laser de baixa intensidade na movimentação ortodôntica - avaliação clínica e radiográfica / Influence of low-level laser irradiation on orthodontic movement clinical and radiographic evaluation

Este estudo é um ensaio clínico randomizado duplo-cego que avaliou a influência do laser de baixa intensidade (LBI) na movimentação ortodôntica de caninos superiores e inferiores, comparando-os aos caninos contralaterais não irradiados (controle). Foram selecionados 11 pacientes, portadores de má oclusão de Classe I com indicação de extração dos primeiros pré-molares superiores e inferiores. O laser infravermelho de baixa intensidade foi aplicado após a ativação da retração inicial dos caninos, realizada através de mola NiTi com uma força de 150g. A aplicação do laser foi realizada em 10 pontos (5 por vestibular e 5 por lingual) nos caninos superiores e inferiores, utilizando o seguinte protocolo, em dose única mensal: canino inferior por vestibular e lingual e canino superior por vestibular Comprimento de onda de 780nm; Potência de 40mW; densidade de energia de 10J/cm2; 10 segundos por ponto; energia por ponto de 0,4J, uma energia total de aplicação de 4J para o canino inferior e 2J por vestibular dos caninos superiores e para o canino superior por palatino o protocolo foi - Potência de 70mW; densidade de energia de 35J/cm2; 20 segundos por ponto; 1,4J de energia por ponto, energia total de 7J por palatino e total de 9J para o canino superior. A retração durou 3 meses, num total de 3 aplicações de laser. Para mensuração da quantidade de movimentação dos caninos retraídos, medições clínicas mensais foram realizadas com paquímetro digital, logo após as extrações dentárias e antes de cada aplicação do laser. Para comparação da velocidade da movimentação ortodôntica entre os lados irradiado e não irradiado nos três períodos avaliados, foi empregada a Análise de Variância a um critério de medidas repetidas, seguida do Teste de Tukey. Para verificação da integridade tecidual, foram efetuadas radiografias periapicais iniciais e finais dos caninos retraídos, nas quais foram avaliados uma possível reabsorção na crista alveolar...

This study is a double-blind randomized clinical trial that evaluated the influence of low-intensity laser on orthodontic movement of upper and lower canine teeth, compared to the non- irradiated contralateral canines (control). Eleven patients with Class I malocclusion with indication of extraction of the first upper and lower premolars were selected. The infrared low-level laser was applied after the activation of initial retraction of the canine teeth, performed with NiTi coil springs with force of 150g. The laser application was performed in 10 points (5 buccal and 5 lingual) in the upper and lower canines, using the following protocol, in an only monthly dose: Lower canine buccal and lingual and upper canine buccal 780 nm wavelength; 40mW power; an energy density of 10 J/cm2; 10 seconds per point; energy per point 0,4J, a total energy of 4J applying to the lower canine and 2J the buccal of the upper canines and upper canine palatally - 70mW of power; an energy density of 35J/cm2; 20 seconds per point; 1,4J energy per point, the total energy 7J and total 9J to the upper canine. The retraction lasted three months, a total of three laser applications. To measure the amount of movement of canines retracted, monthly clinical measurements were made with a digital caliper (Mitutoyo - Japan), after tooth extractions and before each laser application. To compare the speed of orthodontic tooth movement between the irradiated and non- irradiated sides at the three movement stages, repeated measures one-way analysis of variance was used, followed by the Tukey test. For evaluation of tissue integrity, initial and final periapical radiographs of retracted canines were obtained, to evaluate a possible alveolar crest resorption by assessment of the distance from the alveolar bone crest to the cementoenamel junction, as well as the level of root resorption by the Levander and Malmgreen index, which was evaluated only...

Influência do laser de baixa intensidade na movimentação ortodôntica - avaliação clínica e radiográfica / Influence of low-level laser irradiation on orthodontic movement clinical and radiographic evaluation

Este estudo é um ensaio clínico randomizado duplo-cego que avaliou a influência do laser de baixa intensidade (LBI) na movimentação ortodôntica de caninos superiores e inferiores, comparando-os aos caninos contralaterais não irradiados (controle). Foram selecionados 11 pacientes, portadores de má oclusão de Classe I com indicação de extração dos primeiros pré-molares superiores e inferiores. O laser infravermelho de baixa intensidade foi aplicado após a ativação da retração inicial dos caninos, realizada através de mola NiTi com uma força de 150g. A aplicação do laser foi realizada em 10 pontos (5 por vestibular e 5 por lingual) nos caninos superiores e inferiores, utilizando o seguinte protocolo, em dose única mensal: canino inferior por vestibular e lingual e canino superior por vestibular Comprimento de onda de 780nm; Potência de 40mW; densidade de energia de 10J/cm2; 10 segundos por ponto; energia por ponto de 0,4J, uma energia total de aplicação de 4J para o canino inferior e 2J por vestibular dos caninos superiores e para o canino superior por palatino o protocolo foi - Potência de 70mW; densidade de energia de 35J/cm2; 20 segundos por ponto; 1,4J de energia por ponto, energia total de 7J por palatino e total de 9J para o canino superior. A retração durou 3 meses, num total de 3 aplicações de laser. Para mensuração da quantidade de movimentação dos caninos retraídos, medições clínicas mensais foram realizadas com paquímetro digital, logo após as extrações dentárias e antes de cada aplicação do laser. Para comparação da velocidade da movimentação ortodôntica entre os lados irradiado e não irradiado nos três períodos avaliados, foi empregada a Análise de Variância a um critério de medidas repetidas, seguida do Teste de Tukey. Para verificação da integridade tecidual, foram efetuadas radiografias periapicais iniciais e finais dos caninos retraídos, nas quais foram avaliados uma possível reabsorção na crista alveolar...

This study is a double-blind randomized clinical trial that evaluated the influence of low-intensity laser on orthodontic movement of upper and lower canine teeth, compared to the non- irradiated contralateral canines (control). Eleven patients with Class I malocclusion with indication of extraction of the first upper and lower premolars were selected. The infrared low-level laser was applied after the activation of initial retraction of the canine teeth, performed with NiTi coil springs with force of 150g. The laser application was performed in 10 points (5 buccal and 5 lingual) in the upper and lower canines, using the following protocol, in an only monthly dose: Lower canine buccal and lingual and upper canine buccal 780 nm wavelength; 40mW power; an energy density of 10 J/cm2; 10 seconds per point; energy per point 0,4J, a total energy of 4J applying to the lower canine and 2J the buccal of the upper canines and upper canine palatally - 70mW of power; an energy density of 35J/cm2; 20 seconds per point; 1,4J energy per point, the total energy 7J and total 9J to the upper canine. The retraction lasted three months, a total of three laser applications. To measure the amount of movement of canines retracted, monthly clinical measurements were made with a digital caliper (Mitutoyo - Japan), after tooth extractions and before each laser application. To compare the speed of orthodontic tooth movement between the irradiated and non- irradiated sides at the three movement stages, repeated measures one-way analysis of variance was used, followed by the Tukey test. For evaluation of tissue integrity, initial and final periapical radiographs of retracted canines were obtained, to evaluate a possible alveolar crest resorption by assessment of the distance from the alveolar bone crest to the cementoenamel junction, as well as the level of root resorption by the Levander and Malmgreen index, which was evaluated only...

Three-month evaluation of vital tooth bleaching using light units-a randomized clinical study.

The aim of this study was to evaluate the color stability of vital bleaching using a halogen unit, laser, or only chemical activation up to three months after treatment. A total of 60 patients were divided into three groups, and their teeth were bleached with 38% hydrogen peroxide using three methods: acceleration of the bleaching process with halogen (eight minutes), laser (30 seconds), or chemical activation only. All teeth were bleached a maximum of four times (4 × 15 minutes) until a change of six shade tabs took place. The color was evaluated both visually and with a spectrophotometer before bleaching, immediately after bleaching, and one and three months after bleaching. Directly after bleaching, the use of halogen showed better results than laser (p≤0.05). One and three months after bleaching, no significant difference was found between the tested methods relative to the shade change, independent of the method of shade evaluation (p>0.05). As far as the color stability is concerned, bleaching with halogen resulted in stable color throughout the three months (p>0.05), whereas the other two methods resulted in whiter teeth after one and three months compared with the color directly after bleaching (p≤0.05). Bleaching with laser needed more time than halogen for the desired shade change (p≤0.05). Although directly after treatment bleaching with halogen resulted in better results, one and three months after bleaching the kind of acceleration used in the bleaching process did not have any effect on the esthetic results.

Efficacy of low-intensity laser therapy in reducing treatment time and orthodontic pain: a clinical investigation.

INTRODUCTION: The long duration of orthodontic treatment is a major concern for patients. A noninvasive method of accelerating tooth movement in a physiologic manner is needed. The aim of this study was to evaluate of the efficacy of low-intensity laser therapy in reducing orthodontic treatment duration and pain. METHODS: Twenty patients requiring extraction of first premolars were selected for this study. We used a randomly assigned incomplete block split-mouth design. Individual canine retraction by a nickel-titanium closed-coil spring was studied. The experimental side received infrared radiation from a semiconductor (aluminium gallium arsenide) diode laser with a wavelength of 810 nm. The laser regimen was applied on days 0, 3, 7, and 14 in the first month, and thereafter on every 15th day until complete canine retraction was achieved on the experimental side. Tooth movement was measured on progress models. Each patient's pain response was ranked according to a visual analog scale. RESULTS: An average increase of 30% in the rate of tooth movement was observed with the low-intensity laser therapy. Pain scores on the experimental sides were significantly lower compared with the control sides. CONCLUSIONS: Low-intensity laser therapy is a good option to reduce treatment duration and pain.

Bactericidal effects of two parameters of Er:YAG laser intracanal irradiation: ex-vivo study.

The success of endodontic treatment depends on the complete elimination of microorganisms from the root canal system, thus the search for new procedures to eliminate them is justified. The aim of this study was to assess bacterial reduction after intracanal irradiation with the Er:YAG laser. The canals of 70 extracted human maxillary canines were prepared up to file #40 using 1% NaOCl, irrigated with 17% EDTA, and then washed with physiological solution activated by ultrasound. The roots were sterilized by autoclaving, inoculated with 10 µl of a suspension containing 1.5 × 10(8) CFU/ml of Enterococcus faecalis ATCC 29212 and incubated at 37°C for 72 h. The canals were irradiated with the Er:YAG laser using two energy settings: 60 mJ and 15 Hz, and 100 mJ and 10 Hz. The remaining bacteria were counted immediately and 48 h after laser irradiation. The results showed a high bacterial reduction at both time points. With 60 mJ and 15 Hz there was an immediate reduction of 99.73% and the reduction was 77.02% after 48 h, and with 100 mJ and 10 Hz there was an immediate reduction of 99.95% and the reduction was 84.52% after 48 h. Although the best results were observed with 100 mJ of energy, the difference between the two settings was not statistically significant. The count performed 48 h after irradiation showed that E. faecalis were able to survive, and can grow even from small numbers.

Microhardness of radicular dentin treated with 980-nm diode laser and different irrigant solutions.

OBJECTIVE: The aim of this study was to evaluate the microhardness of radicular dentin after treatment with 980-nm diode laser and different irrigant solutions. BACKGROUND DATA: There are few reports of the consequences of diode laser irradiation emitted at 980 nm on the mechanical properties of dentin. METHODS: Seventy-two single canal, human canines with complete root formation were randomly distributed among three groups (n=24), according to the irrigant solution used in the biomechanical preparation: distilled water; 1% NaOCl; and, 1% NaOCl + 17% EDTA. These groups subsequently were divided into three subgroups (n=8), according to the diode laser parameter: no irradiation (control); 1.5 W/100 Hz; and 3.0 W/100 Hz. Laser was applied with helicoidal movements for 20 sec. Roots were sectioned in slices and the fragment corresponding to the middle third was submitted to the microhardness test (KHN) at depths of 30, 90, 150, and 300 µm. RESULTS: ANOVA and Tukey tests showed that the microhardness of the groups irradiated with 1.5 W/100 Hz (49.7±11.2) and 3.0 W/100 Hz (50.6±11.9) were statistically similar to each other (p>0.05) and different (p<0.05) from the non-irradiated group (45.0±9.7). Higher microhardness values were obtained at 150 µm (49.2±11.0) and 300 µm (52.3±11.3) which were similar among themselves and different (p<0.05) only at the depth of 30 µm (44.4±10.5). No differences were found among the irrigant solutions (p>0.05). CONCLUSIONS: The microhardness of the radicular dentin increased after irradiation with 980-nm diode laser.

Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation.

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

The effect of a 980 nm diode laser with different parameters of irradiation on the bond strength of fiberglass posts.

The aim of this study was to assess bond strength of fiberglass posts to root canal dentin irradiated with a 980 nm diode laser at different parameters of power and frequency. Fifty human maxillary canines were separated into five groups (n = 10) according to the following parameters of laser power and frequency: Group 1 (1.5 W/100 Hz), Group 2 (1.5 W/continuous wave [CW]), Group 3 (3.0 W/100 Hz), Group 4 (3.0 W/CW), and Group 5 (no irradiation). Following post cementation, samples underwent a push-out test (0.5 mm/min); next, fracture analysis was performed with a light microscope at 50x and 100x magnification. All of the irradiated groups had increased bond strength values compared to the nonirradiated group. Groups 1 and 2 demonstrated the highest bond strength values; however, statistically significant differences were observed for only the cervical third of Group 4 and the cervical/apical thirds of Group 5. Fracture analysis showed a predominance of mixed failures for Groups 1 and 2 and adhesive failures between dentin and cement for the other groups.

Influence of low-level laser on the speed of orthodontic movement.

INTRODUCTION: This study evaluated the effect of low-level laser irradiation on the speed of orthodontic tooth movement of canines submitted to initial retraction. METHODS: Twenty-six canines were retracted by using NiTi spring (force of 150 g/side). Thirteen of those were irradiated with diode laser (780 nm, 20 mW, 10 sec, 5 J/cm(2)) for 3 days, and the other 13 were not irradiated and thus were considered the control group. Patients were followed up for 4 months, and nine laser applications were performed (three each month). The movement of the canines was evaluated through 3D casts, and the statistical analysis was performed with ANOVA and Tukey tests (p < 0.05). Periapical radiographs of the studied teeth were submitted to Levander, Malmgreen, and alveolar bone ridge analyses to evaluate tissue integrity and were compared with the Wilcoxon test (p < 0.05). RESULTS: A statistically significant increase in the movement speed of irradiated canines was observed in comparison with nonirradiated canines in all evaluation periods. No statistically significant difference was observed in bone and root resorption of canines, whether irradiated or not. CONCLUSION: The diode laser used within the protocol guidelines increased the speed of tooth movement. This might reduce orthodontic treatment time.

Effectiveness of Er,Cr:YSGG laser on dentine hypersensitivity: a controlled clinical trial.

AIM: Attempts have been made to treat dentine hypersensitivity (DH) with lasers. However, there is limited knowledge on the effects of erbium, chromium-doped:yttrium, scandium, gallium and garnet (Er,Cr:YSGG) laser on DH. The aim of this study was to evaluate the efficacy of Er,Cr:YSGG laser on reduction in DH. METHODS: Forty-two patients (146 teeth) were included. Teeth were assigned to an experimental group and irradiated with the Er,Cr:YSGG laser. In the control group same clinical instrument was used without laser emission. DH was assessed for both groups utilizing the visual analog scale. Plaque index (PI) scores were recorded immediately following treatment, at 1 week, 1 and 3 months. RESULTS: The results showed that Er,Cr:YSGG laser irradiation had a significantly higher desensitizing effect compared with the placebo immediately after treatment (p<0.05). Intra-group comparisons revealed no statistically significant differences within the placebo group (p>0.05). For the test group, the differences between baseline and all time points following treatment were statistically significant (p<0.05). No significant differences were observed in PI between the test and control groups at any follow-up examination (p>0.05). CONCLUSION: Within the limits of this study, it appears that Er,Cr:YSGG laser is effective in the treatment of DH compared with the placebo treatment.

Apical microleakage and SEM analysis of dentin surface after 980 nm diode laser irradiation

This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.

Este estudo avaliou o efeito do laser de diodo 980 nm na microinfiltração apical e na morfologia intrarradicular da dentina. Raízes de 110 incisivos inferiores foram utilizadas no estudo: 92 para o teste de microinfiltração e 18 para microscopia eletrônica de varredura (MEV). As raízes foram divididas em 3 grupos de acordo com a solução irrigante (água, NaOCl e NaOCl/EDTA) e subdivididas em 3 de acordo com a irradiação laser (sem irradiação, irradiados com 1,5 W e irradiados com 3,0 W). Duas amostras de cada subgrupo foram preparadas para MEV. As raízes restantes foram preenchidas com AH Plus e guta percha. A infiltração apical foi avaliada nas raízes por meio da penetração do corante e os dados foram analisados por ANOVA e teste de Tukey-Krammer (α=0,05). Os resultados da MEV mostraram intensificação das mudanças quando se aumentou a potência do laser e variações de acordo com a solução irrigadora. Camada de smear modificada foi observada em espécimes tratados com água e irradiados com laser. Raízes irrigadas com NaOCl/EDTA tiveram níveis menores de infiltração (0,17 ± 0,18 mm) estatisticamente diferente (p<0,05) das raízes irrigadas com água (0,34 ± 0,30 mm), mas semelhante (p>0,05) aos irrigados com NaOCl (0,28 ± 0,29 mm). As raízes não irradiadas tiveram níveis menores de infiltração (0,10 ± 0,14 mm), diferente (p<0,05) de 1,5 W (0,32 ± 0,22 mm) e 3.0 W (0,37 ± 0,32 mm). O laser de diodo 980 nm alterou a morfologia da dentina e aumentou a infiltração marginal apical.

Color differences of canines and incisors in a comparative long-term clinical trial of three bleaching systems.

This study was a long-term clinical trial of home and in-office LED and laser bleaching systems comparing for the first time interdental color differences (differences between the central labial surfaces of the canine and the central incisor). A total of 90 patients were divided into three groups of 30 each. One group received day guard vital bleaching, and the other two groups received one bleaching session for 20 min accelerated by a diode laser for 30 s per tooth or a blue LED for 3 min per tooth, and both groups received additionally day guard for 7 days. A total of four color measurements were carried out during the study period of 3 months and 3 weeks. The group treated with the LED tended to show the highest degree of equalization of lightness, chroma and hue. A significantly stronger overall increase in lightness was observed for canines after treatment when compared with incisors resulting in more homogeneous lightness values.

Temperature variation at the external root surface during 980-nm diode laser irradiation in the root canal.

OBJECTIVE: To assess the temperature variation in the cervical, middle and apical thirds of root external wall, caused by 980-nm diode laser irradiation with different parameters. METHODS: The roots of 90 canines, had their canals instrumented and were randomly distributed into 3 groups (n=30) according to the laser potency (1.5 W, 3.0 W and 5.0 W). Each group was subdivided into 3 (n=10) according to the frequency (CM, 100 Hz and 1000 Hz), and each subgroup divided into 2 (n=5): dried canal or filled with distilled water. The maximum temperature values were collected by 3 thermocouples located at each third of the root external wall and recorded by digital thermometers. RESULTS: The groups irradiated in the continuous mode (CM) presented the highest values (11.82+/-5.78), regardless of the canals were dry or not, which were statistically different (p<0.01) from those obtained with 100 Hz (6.22+/-3.64) and 1000 Hz (6.00+/-3.36), which presented no statistical difference between them (p>0.01). The groups irradiated with 5.0 W presented the greatest temperature variation (12.15+/-5.14), followed by 3.0 W (7.88+/-3.92) and 1.5 W (4.02+/-2.16), differing between them (p<0.01). The cervical third of the root presented the highest temperature rises (9.68+/-5.80), followed by the middle (7.66+/-4.87) and apical (6.70+/-4.23), with statistical difference among them (p<0.01). After 30s from the end of irradiation, all the specimens presented temperature variation lower than 10 degrees C. CONCLUSIONS: Application of 980-nm diode laser in the root, at 1.5 W in all operating modes, and 3.0 W, in the pulsed mode, for 20s, can safely be used in endodontic treatment, irrespective of the presence of humidity.

Effects of low-level laser therapy on the rate of orthodontic tooth movement.

OBJECTIVES: To test the hypothesis that mechanical forces combined with low-level laser therapy stimulate the rate of orthodontic tooth movement. STUDY DESIGN: This study was a double blind, randomized placebo/control matched pairs clinical trial to test the efficacy of GaAlAs low-level laser therapy (LLLT) on 12 young adult patients who required retraction of maxillary canines into first premolar extraction spaces using tension coil springs with fixed edgewise appliance. LLLT was applied on the mucosa buccally, distally and palatally to the canine on the test side and using a pseudo-application on the placebo side. Dental impressions and casts were made at the commencement of the trial and at the end of the first, second and third months after starting the trial. Measurement of tooth movements was made on each stage model using a stereo microscope. RESULTS: There was no significant difference of means of the canine distal movement between the LLLT side and the placebo side for any time periods (p-value = 0.77). CONCLUSION: The energy density of LLLT (GaAlAs) at the surface level in this study (25 J/cm(2)) was probably too low to express either stimulatory effect or inhibitory effect on the rate of orthodontic tooth movement.