Electron microscopic changes in human pulps after intraligamental injection

Because of its advantages, intraligamental injection is becoming a popular anesthetic technique to achieve anesthesia in vital pulps. This study investigated the possible effects of intraligamental injection on human pulps under electron microscope. Forty-two mandibular and maxillary premolars were scheduled to be extracted for orthodontic reasons after being anesthetized with intraligamental injections of 2% lidocaine, 1:100,000 epinephrine (experimental group). The same anesthetic solution was used on the contralateral teeth with either nerve or field blocks (control group). To examine the effects of ischemia on odontoblasts, 12 anesthetized premolars were extracted, and their pulps were placed in physiologic saline solution for different time intervals (15 minutes to 6 hours). The teeth in the experimental and control groups were then reanesthetized with nerve or field blocks of 3% carbocaine without epinephrine after time periods that ranged from 15 minutes to 28 days. After extraction, the teeth were sectioned vertically and their pulps were fixed in 3% glutaraldehyde. The odontoblastic layer of each pulp was examined under electronic microscope. Nuclear and cytoplasmic changes started an hour after ischemia in the pulps placed in physiologic saline. In contrast, little or no cellular changes occurred in pulps of the experimental or controls groups. On the basis of the results, it appears that intraligamental injection has no long-term deleterious effects on pulps of young human premolars.