Purpose: The purpose of this study was to evaluate the histological changes in dental pulp tissue after diode laser pulpotomy, with an attempt to standardise the duration of laser exposure time. Materials and Methods: Forty-two premolars from six healthy 1-yr-old Coorg local breed dogs were selected. Pulpotomy was initiated after achieving adequate anaesthesia. Hemostasis was achieved by exposure to diode laser (810 nm) at 2 W for 1 s in group II, 3 s in group III, 5 s in group IV, while group I was not treated and used as negative control. The teeth were extracted at the end of 24 h and 7 days. Histological sections using hematoxylin and eosin-stained pulp tissues were made and evaluated by an optical microscope for tissue necrosis, extent of inflammation and extent of pulpal fibrosis, pulpal edema and vascular changes. Results: A necrotic layer surrounded by both acute and chronic inflammatory cells was a common finding adjacent to pulp interface. Only one specimen in group IV showed signs of internal resorption in the dentinal wall. Intact odontoblasts were maintained in most of the specimens but were found disrupted in a few specimens in groups III and IV. Conclusion: Most regressive changes were seen with 5-s laser application. One- and 3- s applications seemed to be ideal for diode laser pulpotomy as most of the specimens showed intact odontoblasts. Hence, diode laser therapy can be an acceptable alternative to the conventional pharmacotherapeutic methods of pulpotomy.
Keywords: pulpotomy, diode laser, exposure time, necrosis, fibrosis, lymphocytic infiltration