Abstract Given the growing trend towards medical indications for continuous use of anticoagulants, the number of patients on these medications continues to rise. The management of patients on oral anticoagulants requiring oral surgical procedures has aroused much controversy. Changes in an anticoagulation regimen are associated with an increased risk of thromboembolism. However, it seems logical and advantageous for the patients’ health if surgery could be performed without any change to the anticoagulation therapy. In dentistry, high-power lasers have been poorly explored in this field. The hemostatic properties of high-power lasers could be helpful during oral soft tissue surgeries in anticoagulated patients. The aim of this study was to compare bleeding time in anticoagulated rats after lingual frenectomy performed with a scalpel or diode laser with bleeding time in healthy animals. Twenty-four male Wistar rats were assigned to four groups (n = 6): (CS) Control-Scalpel Surgery; (AS) Anticoagulated-Scalpel Surgery; (CL) Control-Laser (diode laser 810 nm/1.5 W) Surgery; and (AL) Anticoagulated-Laser Surgery (diode laser 810 nm/1.5 W). Warfarin administration was used to induce anticoagulation. Blood was blotted every 30 seconds with filter paper until bleeding stopped to verify bleeding time. Two blinded researchers performed the surgeries and collected the bleeding time data. Diode laser surgery led to complete hemostasis in rats during and after lingual frenectomy. Zero bleeding was assessed during surgeries and after diode laser surgeries in anticoagulated rats. Laser-induced hemostasis offered an alternative solution to the controversial issue of intraoperative and postoperative bleeding control in patients on anticoagulation therapy.

This in vitro study aimed to investigate the potential of CO2 lasers associated with different fluoride agents in inhibiting enamel erosion. Human enamel samples were randomly divided into 9 groups (n = 12): G1-eroded enamel; G2-APF gel; G3-AmF/NaF gel; G4-AmF/SnF2 solution; G5-CO2 laser (λ = 10.6 µm)+APF gel; G6-CO2 laser+AmF/NaF gel; G7-CO2laser+AmF/SnF2solution; G8-CO2 laser; and G9-sound enamel. The CO2 laser parameters were: 0.45 J/cm2; 6 μs; and 128 Hz. After surface treatment, the samples (except from G9) were immersed in 1% citric acid (pH 4.0, 3 min). Surface microhardness was measured at baseline and after surface softening. The data were statistically analyzed by one-way ANOVA and Tukey’s tests (p < 0.05). G2 (407.6 ± 37.3) presented the highest mean SMH after softening, followed by G3 (407.5 ± 29.8) and G5 (399.7 ± 32.9). Within the fluoride-treated groups, G4 (309.0 ± 24.4) had a significantly lower mean SMH than G3 and G2, which were statistically similar to each other. AmF/NaF and APF application showed potential to protect and control erosion progression in dental enamel, and CO2 laser irradiation at 0.45J/cm2 did not influence its efficacy. CO2 laser irradiation alone under the same conditions could also significantly decrease enamel erosive mineral loss, although at lower levels.

Studies have shown the cariostatic effect of Er,Cr:YSGG (2.78 mm) laser irradiation on human enamel and have suggested its use on caries prevention. However there are still no reports on the intrapulpal temperature increase during enamel irradiation using parameters for caries prevention. The aim of this in vitro study was to evaluate the temperature variation in the pulp chamber during human enamel irradiation with Er,Cr:YSGG laser at different energy densities. Fifteen enamel blocks obtained from third molars (3 x 3 x 3 mm) were randomly assigned to 3 groups (n=5): G1 - Er,Cr:YSGG laser 0.25 W, 20 Hz, 2.84 J/cm², G2 - Er,Cr:YSGG laser 0.50 W, 20 Hz, 5.68 J/cm², G3 - Er,Cr:YSGG laser 0.75 W, 20 Hz, 8.52 J/cm². During enamel irradiation, two thermocouples were fixed in the inner surface of the specimens and a thermal conducting paste was used. One-way ANOVA did not show statistically significant difference among the experimental groups (a=0.05). There was intrapulpal temperature variation <0.1ºC for all irradiation parameters. In conclusion, under the tested conditions, the use of Er,Cr:YSGG laser with parameters set for caries prevention lead to an acceptable temperature increase in the pulp chamber.

O objetivo do presente estudo foi analisar morfologicamente, através de microscopia eletrônica de varredura, os efeitos do laser de Er:YAG no tratamento de superfícies radiculares submetidas à raspagem e aplainamento radicular com instrumentos manuais. Foram utilizados 18 espécimes (n = 18) de superfícies radiculares que após ser submetidos à raspagem e aplainamento radicular foram divididos em 3 grupos (n = 6). O grupo controle (G1) não sofreu nenhum tratamento; Grupo 2 (G2) foi irradiado com laser de Er:YAG (2,94 mim) 47 mJ/10 Hz, focalizado,com refrigeração à água durante 15 s e fluência de pulso de 0,57 J/cm²; Grupo 3 (G3) foi irradiado com laser de Er:YAG (2,94 mim), 83 mJ/10 Hz, focalizado, com refrigeração à agua durante 15 s e fluência de pulso de 1,03 J/cm². Através da análise dos resultados podemos concluir que o laser de Er:YAG nos parâmetros utilizados no G3 promove a remoção de "smear layer" da superfície radicular e exposição dos túbulos dentinários, porém o laser promove aspecto irregular na superfície, apesar de não demonstrar crateras, fendas, fraturas e carbonização, necessitando de estudos que demonstrem a biocompatibilidade desta superfície no processo de reparo periodontal.

The purpose of this study was to morphologically evaluate, by means of scanning electron microscopy, the effects of Er:YAG laser on the treatment of root surfaces submitted to scaling and root planing with conventional periodontal instruments. Eighteen root surfaces (n = 18), which had been previously scaled and planed, were assigned to 3 groups (n = 6). The control Group (G1) received no further treatment; Group 2 (G2) was irradiated with Er:YAG laser (2.94 mum), with 47 mJ/10 Hz, in a focused mode with air/water spray during 15 s and with 0.57 J/cm² of fluency per pulse; Group 3 (G 3) was irradiated with Er:YAG laser (2.94 mum), with 83 mJ/10 Hz, in a focused mode with air/water spray during 15 s and with 1.03 J/cm² of fluency per pulse. We concluded that the parameters adopted for Group 3 removed the smear layer from the root surface, exposing the dentinal tubules. Although no fissures, cracks or carbonized areas were observed, an irregular surface was produced by Er:YAG laser irradiation. Thus, the biocompatibility of the irradiated root surface, within the periodontal healing process, must be assessed.

Este estudo foi conduzido a fim de comparar a resistência à força de cisalhamento de uma resina composta aderida à superfície do esmalte dental após condicionamento com ácido fosfórico a 35% ou com a irradiação de um laser Nd:YAG, com densidade de energia de 165,8 J/cm2 por pulso. Após o condicionamento e a adaptação da resina a essas superfícies, os espécimes sofreram ciclagem térmica e foram, então, submetidos ao teste de resistência à força de cisalhamento em uma velocidade de 5 mm/min. Os resultados encontrados, após análise estatística pelo teste t de Student, revelaram que a adesão foi significantemente maior no grupo tratado pelo ácido fosfórico a 35% do que no grupo tratado pelo laser Nd:YAG, revelando, dessa forma, a necessidade do desenvolvimento de novos estudos, a fim de se alcançarem os parâmetros ideais para o condicionamento da superfície do esmalte, bem como adesivos e resinas compostas específicas, quando o laser Nd:YAG é utilizado

This study has been focused on a comparison between the shear bond strength of a composite resin attached to dental enamel surface, after a 35% phosphoric acid etching and after a Nd:YAG laser irradiation with 165.8 J/cm2 of energy density per pulse. After etching and attaching resin to these surfaces, the specimens were thermocycled and then underwent the shearing bond strength tests at a speed of 5 mm/min. The results achieved, after statistical analysis with Student's t-test, showed that the adhesion was significantly greater in the 35% phosphoric acid treated group than in the group treated with the Nd:YAG laser, thus demonstrating the need for developing new studies to reach the ideal parameters for an effective enamel surface conditioning as well as specific adhesives and composite resins when Nd:YAG laser is used