PREEMPTIVE ANALGESIA USING LOCAL-ANESTHESIA - A STUDY IN BILATERALLY SYMMETRICAL SURGERY

Two studies were carried out in patients undergoing bilaterally symmet rical lower third molar surgery under general anaesthesia. In the firs t study observations were carried out in 40 patients, using McGill pai n questionnaires and visual analogue scales (VAS), to assess the varia tion in pain intensity between the two sides in each individual on the morning after surgery. The within-patient variation in pain intensity indicated that a sample size exceeding 30 was required to show a diff erence of more than 10 mm on the VAS and achieve a power of 90% at the 5% level of significance. The second study was carried out to determi ne if local anaesthesia administered before rather than after tooth re moval rendered any benefit. Each of the 38 patients acted as their own control; one side was allocated randomly to receive the local anaesth etic before operation and the other side after operation. The differen ce in pain between the pretreated and post-treated sides in each indiv idual was assessed using a McGill pain questionnaire on the morning af ter surgery in addition to two VAS (one for each operation side) after operation, at 6 h, 1 and 6 days after surgery. There were no signific ant differences in pain at any time using any of the above methods.