Introduction Ankylosis is a serious and handicapping problem and has been associated with a lot of hazards from chewing problems and malnutrition up to frank sleep apnoea syndrome (OSA) and life threatening upper air way complications during anaesthesia. On the other hand, trigeminocardiac reflex (TCR) consists of dysrhythmias, hypotension, apnoea and gastric hypermotility. Clinically, it is encountered in cranio-maxillo facial and occular surgeries. In this study we try to study the incidence of TCR due to forcible mouth opening by bi-block prosthesis following TMJ procedures after regional nerve blocks of maxillary and mandibular nerves. Materials and methods 100 patients enrolled for TMJ surgeries are grouped into 2 groups each containing 50 patients, control group (C-group) and nerve block group (NB-group) in which maxillary and mandibular nerves are blocked. Acrylic – bi-block prosthesis is inserted. The incidence of TCR (which is defined by a drop in both HR and MABP in > 20% of the base line values), also lowest H.R, occurrence of asystole, dysrhythmias and lanyngospasm, all are reported intraoperatively. Results There is a significant drop of incidence of TCR in the NB group (0%) compared to the C-group (2/50 – 4%). The lowest H.R. is insignificantly higher in the NB-group (49+3) Than the C-group (44+2). There was no haemodynamically significant hypotension, arrhythmias or laryngospasm. Conclusion Prophylactic nerve blockade at end of TMJ procedures and before bi-block prosthesis application is efficient to reduce the incidence of TCR.