Root surface treatment using diode laser in delayed tooth replantation: radiographic and histomorphometric analyses in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Background aim: The aim of this study was to evaluate, by radiographic and histomorphometric analyses, the effects of high-power diode laser irradiation on the root surfaces of delayed replanted rat teeth. Material and methods: Maxillary right incisors were extracted from 60 Wistar rats and kept dry for 60 min. Subsequently, the root canals were prepared and filled with calcium hydroxide paste. According to the root surface treatment before the replantation, the teeth were assigned to four groups (n = 15): G1 (negative control) no root surface treatment; G2 (positive control) treated with 2% sodium fluoride solution; G3 irradiated with a high-power diode laser (810 nm, continuous mode, 1.0 W, 30 s); and G4 irradiated with a diode laser using the same parameters as those used for G3 but in pulsed mode. The rats were euthanized after 15, 30, and 60 days of replantation. The specimens were digitally radiographed and processed for histomorphometric analysis to determine the average root resorption areas and to evaluate the histological events. Results: The percentage of root resorption was in the following order: G1 > G2 > G4 > G3. Both histomorphometric and radiographic analyses showed significantly lower means (P < 0.05) of the occurrence of root resorption in the irradiated groups (G3 and G4) when compared to the control groups (G1 and G2). Replacement resorption and ankylosis were observed in histological sections only after 30 and 60 days; however, such events were not observed in G3. Conclusion: Root surface treatments with high-powered diode laser irradiation prior to delayed replantation reduced the occurrence of external root resorption compared to no treatment or sodium fluoride treatment at up to 60 days.