Efeitos do laser de diodo de alta potência e da fotobiomodulação em dentes de ratos reimplantados tardiamente / Effects of high power diode laser and photobiomodulation therapy prior delayed replantation in rats

Resumo Introdução A busca por protocolos efetivos para reduzir a incidência de reabsorções radiculares e favorecer a reparação do ligamento periodontal perdido ainda representa um grande desafio, tendo em vista o prognóstico desfavorável dos reimplantes dentais tardios. Objetivo Avaliar, por meio da análise histológica, os efeitos do laser de alta potência e da fotobiomodulação na ocorrência de reabsorção radicular e no reparo periodontal, em dentes reimplantados tardiamente. Material e método Foram utilizados 50 incisivos centrais direitos de ratos Wistar. Após a extração, os espécimes foram divididos em cinco grupos (n = 10): G1 (controle positivo): reimplante imediato; G2 (controle negativo): reimplante tardio (RT): espécimes mantidos em ambiente seco por 60 minutos, sem tratamento adicional; G3: RT associado ao tratamento da superfície radicular com laser diodo de alta potência (810 nm, 1.5 W); G4: RT + superfícies radiculares e feridas alveolares tratadas com fotobiomodulação (laser diodo 660 nm, 30 mW e 780 nm, 40 mW, respectivamente); G5: RT + superfícies radiculares irradiadas com laser de alta e alvéolos com fotobiomodulação, nos mesmos parâmetros que G3 e G4, respectivamente. Após 60 dias, os animais foram eutanasiados. Os espécimes foram processados para análise histológica. Resultado G3 e G5 apresentaram as menores médias de scores com relação à ocorrência de reabsorções radiculares e anquilose, quando comparados a G2 e G4 (Teste Kruskall-Wallis, p<0,05). Com relação ao reparo periodontal, todos os grupos experimentais (G3, G4 e G5) apresentaram médias de escores inferiores (Teste Kruskall-Wallis, p<0,05) comparadas ao G1 e semelhantes ao G2 (Teste Kruskall-Wallis, p>0,05). Conclusão O laser de alta potência, associado ou não à fotobiomodulação, diminuiu a ocorrência das reabsorções radiculares e da anquilose, e a fotobiomodulação não favoreceu o controle das reabsorções radiculares nem o reparo periodontal.

Abstract Introduction The search for effective protocols for a lower incidence of root resorptions reduction and for a favor periodontal repair still represents a great challenge, considering the unfavorable prognostic of the delayed replanted tooth. Objective To evaluate by histologic analyses the effects of high power diode laser and photobiomodulation on the occurrence of root resorption and on the tissue repair of delayed replanted teeth. Material and method Fifty right central incisors of Wistar rats were used. After the extraction, the specimens were assigned to 5 groups (n=10): G1 and G2 were the control groups-with no treatment and they were respectively submitted to immediate and delayed replantation (DR- 60 minutes after the extraction). The other three groups received tissue repair treatment prior the DR: G3 - root surfaces were irradiated with high power laser (810 nm, 1.5 W); G4- root surfaces and the alveolar wounds were irradiated with low power laser (photobiomodulation), respectively with 660 nm, 90 mW and 780 nm, 40 mW; G5- root surfaces were irradiated with high power and the alveolar wound received photobiomodulation with the same parameters used in G3 and G4. After 60 days the animals were euthanized. The specimens were processed for histological analyses. Result The histologic analysis showed lower means values of scores of root reabsorptions and ankylosis in G3 and G5 when compared to G2 and G4 (Kruskall-Wallis test, p>0.05). Regarding the periodontal repair, all the experimental groups (G3, G4 and G5) presented lower means values of scores than G1 (Kruskall-Wallis test, p <0.05) and similar values to G2 (Kruskall-Wallis test, p>0.0.5). Conclusion High power laser reduced the occurrence of root resorption and photobiomodulation did not enhance the tissue healing process in delayed tooth replantation in rats.

Assessment of smear layer removal protocols in curved root canals.

This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty-four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1 mL of 17% ethylenediaminetetraacetic acid (EDTA) ), 5EDTA (syringe irrigation with 5 mL of 17% EDTA), 1EDTA-P (syringe irrigation with 1 mL of 17% EDTA + pumping with gutta-percha point), 5EDTA-P (syringe irrigation with 5 mL of 17% EDTA + pumping with gutta-percha point), 1EDTA-EA (syringe irrigation with 1 mL of 17% EDTA + EndoActivator) and 5EDTA-EA (syringe irrigation with 5 mL of 17% EDTA + EndoActivator). Final rinsing was carried out over 3 min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA-EA group and the other groups (Kruskal-Wallis and Dunn's post-hoc tests, P < 0.05). The combination of 5 mL of 17% EDTA and 3 mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used.

Effect of chemical substances in removing methylene blue after photodynamic therapy in root canal treatment.

BACKGROUND AND OBJECTIVE: The disadvantage of photodynamic therapy (PDT) is in the photosensitizing agents that may stain the tooth structure. There is no register of PDT studies evaluating protocols to minimize that concern. The present study evaluated the efficiency of chemical adjuncts in methylene blue dye (MB) removal after PDT. MATERIALS AND METHODS: Forty single-rooted teeth, after root canal preparation, were filled with 0.01% MB for 5 min, and irradiated with diode laser 660 nm at 40 mW for 240 sec (total energy 9.6 J). The specimens were divided into four groups (n = 10), according to the chemical adjuncts used for dye removal: (a) 2.5% sodium hypochlorite (NaOCl); (b) 2.5% NaOCl + Endo-PTC cream; (c) 70% ethyl alcohol and (d) saline (control). The crowns were sectioned and fixed in a device. Photographs were taken before the PDT (T0), immediately after (T1) and upon dye removal (T2). The chromatic alterations were evaluated using Adobe Photoshop and K values were determined in four fixed points of each crown. RESULTS: K values (dental staining) increased in all groups when comparing T0 and T1. The effectiveness of the tested adjuncts was, in decreasing order: G1 (-3.11) > G2 (-2.97) > G3 (-1.28) > G4 (-1.19), not observing significant statistical differences (p < 0.05) between G1 and G2 and also between G3 and G4. CONCLUSIONS: Protocols to remove photosensitizing dyes should be applied after PDT in order to minimize dental stain. The protocols tested in this study by using 2.5% NaOCl, associated or not with Endo-PTC cream, were effective in avoiding tooth staining caused by MB during PDT.

Effect of nitric oxide inhibitor and donor substances on the inflammatory process caused by endodontic irrigants.

UNLABELLED: Nitric oxide (NO) has been considered a key molecule in inflammation. OBJECTIVE: The aim of this study was to evaluate the effect of treatment with L-NAME and sodium nitroprussiate, substances that inhibit and release NO, respectively, on tissue tolerance to endodontic irrigants. MATERIAL AND METHODS: The vital dye exudation method was used in a rat subcutaneous tissue model. Injections of 2% Evans blue were administered intravenously into the dorsal penial vein of 14 male rats (200-300 g). The NO inhibitor and donor substances were injected into the subcutaneous tissue in the dorsal region, forming two groups of animals: G1 was inoculated with L-NAME and G2 with sodium nitroprussiate. Both groups received injections of the test endodontic irrigants: acetic acid, 15% citric acid, 17% EDTA-T and saline (control). After 30 min, analysis of the extravasated dye was performed by light absorption spectrophotometry (620 nm). RESULTS: There was statistically significant difference (p<0.05) between groups 1 and 2 for all irrigants. L-NAME produced a less intense inflammatory reaction and nitroprussiate intensified this process. CONCLUSIONS: Independently of the administration of NO inhibitors and donors, EDTA-T produced the highest irritating potential in vital tissue among the tested irrigating solutions.

Effect of nitric oxide inhibitor and donor substances on the infammatory process caused by endodontic irrigants

Nitric oxide (NO) has been considered a key molecule in infammation. OBJECTIVE: The aim of this study was to evaluate the effect of treatment with L-NAME and sodium nitroprussiate, substances that inhibit and release NO, respectively, on tissue tolerance to endodontic irrigants. MATERIAL AND METHODS: The vital dye exudation method was used in a rat subcutaneous tissue model. Injections of 2 percent Evans blue were administered intravenously into the dorsal penial vein of 14 male rats (200-300 g). The NO inhibitor and donor substances were injected into the subcutaneous tissue in the dorsal region, forming two groups of animals: G1 was inoculated with L-NAME and G2 with sodium nitroprussiate. Both groups received injections of the test endodontic irrigants: acetic acid, 15 percent citric acid, 17 percent EDTA-T and saline (control). After 30 min, analysis of the extravasated dye was performed by light absorption spectrophotometry (620 nm). RESULTS: There was statistically signifcant difference (p<0.05) between groups 1 and 2 for all irrigants. L-NAME produced a less intense infammatory reaction and nitroprussiate intensifed this process. CONCLUSIONS: Independently of the administration of NO inhibitors and donors, EDTA-T produced the highest irritating potential in vital tissue among the tested irrigating solutions.

Attachment of cultured fibroblasts and ultrastructural analysis of simulated cervical resorptions treated with high-power lasers and MTA.

OBJECTIVE: The present study evaluated the fibroblast attachment and the morphologic changes of simulated cervical root resorptions after irradiation with high-power lasers and the use of mineral trioxide aggregate (MTA). STUDY DESIGN: Standardized cavities were done on the coronal third of 40 single-rooted teeth and assigned into 4 groups according to the treatment applied: (1) untreated control, (2) use of MTA, (3) irradiation with Er:YAG laser (42 mJ, 10 Hz, 10 s), and (4) irradiation with high-power diode laser (1 W, 10 s). Fragments were prepared for SEM analysis: 6 samples of each group were plated with human gingival fibroblasts and 4 samples were used for ultrastructural analysis. RESULTS: The cells' attachment was in decreasing order: G3 > G4 > G1> G2, with statistical differences among all groups (P < .05). The samples irradiated with Er:YAG exhibited roughness on the dentinal surface, no smear layer, and open dentinal tubules; those irradiated with diode laser exhibited a smooth surface, more smear layer, and closed dentinal tubules; and the control group showed high amount of smear layer and closed dentin tubules. CONCLUSIONS: Irradiation with Er:YAG and diode lasers caused morphologic changes on the dentinal surfaces of simulated resorptions that favored cells' adhesion. MTA showed lower biocompatibility than irradiated groups but allowed cells' adhesion.

Treatment options for teeth with open apices and apical periodontitis.

Three clinical cases involving teeth with open apices and apical periodontitis were treated using different protocols. The first case was managed with intracanal calcium hydroxide paste for 12 months before obturation with gutta-percha and sealer. In the second case, an apical plug of mineral trioxide aggregate (MTA) was used before obturation with gutta-percha and sealer and treatment was completed during 2 appointments. In the third case, the tooth, which had a divergent root canal system, was completely obturated with MTA and treatment was also completed over 2 appointments. In all 3 cases, signs of bone healing were observed after treatment.