A systematic review by Dr. Yingying Su, et al published in the Journal of Endodontics compared the healing rate and postobturation pain of single- versus multiple-visit root canal treatment for teeth with infected root canals. The literature search was "exhaustive" and was combined with specified inclusion criteria to identify randomized or quasi-randomized controlled trials comparing root canal treatment in single and multiple appointments (2 or more visits) in patients with infected root canals. The review found no significant difference in the healing rate between single- versus multiple-visit root canal treatment, nor any significant difference in the incidence of medium-term postobturation pain. In the short-term follow-up, the prevalence of postobturation pain was significantly lower in single-visit than in the multiple-visit group.
Dr. Su, et al concluded in this review that on the basis of current studies, the healing rate of single- and multiple-visit root canal treatment is similar for infected teeth. Patients experience less frequency of short-term postobturation pain after single-visit treatment than those patients having multiple-visit root canal treatment.
(Source: Journal of Endodontics, February 2011, Volume 37, Issue 2, Pages 125 to 132)