SENSORY CHANGES IN THE TERRITORY OF THE LINGUAL AND INFERIOR ALVEOLARNERVES FOLLOWING LOWER 3RD-MOLAR EXTRACTION

Post-injury inflammation activates nociceptive systems and recruits no rmally non-nociceptive efferents into a pain processing role. During i nflammation, A beta low threshold mechanoreceptor afferents that usual ly mediate tactile sensation acquire properties of nociceptors, allowi ng them to participate in post-injury spontaneous pain and evoked abno rmalities such as tenderness and pain to light touch. This study asses sed the sensory consequences of post-injury inflammation following ext raction of a single, lower third molar tooth. Extensive bilateral eval uations were performed in the territory of nerves assumed to be expose d to both inflammation and mechanical trauma, inflammation alone, or o nly the central consequences of peripheral inflammation. Testing at th e distal termination of nerves assumed to be exposed to local inflamma tion (mental and lingual nerve territory) revealed decreased detection thresholds (P < 0.05) to electrical stimulation and to mechanical sti mulation by sensitive, disposable filaments developed and validated fo r this application. Testing at sites of assumed inflammation and mecha nical trauma (mental nerve territory) showed reduced pain thresholds t o electrical stimulation. Thermal detection and pain thresholds were n ot altered at any location in patients, and no effects were observed i n control subjects receiving only local anesthetic injections. These r esults in humans are consistent with recent experimental evidence that inflammatory processes alter the central consequence of activity in l arge-diameter A beta touch primary afferents evoked under natural cond itions by gentle mechanical stimulation. These effects result in hyper esthesia, increased sensitivity to light touch, and mechanical allodyn ia, pain evoked by normally innocuous stimulation of A beta primary af ferents. (C) 1998 International Association for the Study of Pain. Pub lished by Elsevier Science B.V.