To compare root canal treatment of teeth with apical periodontitis (AP) in a single or two visits, using cone beam computed tomography (CBCT).

Twenty-six pairs of teeth (13 patients) were assigned to two groups: Group single-session (GSS): Instrumentation and root canal filling in the same session; and group two-session (GTS): A calcium hydroxide intracanal medication (Calen^® paste) was used for 14 days between two sessions. Cone beam computed tomography scans were obtained before and 12 months after treatment. The pre- and postoperative volume of the AP lesions was measured in mm³. The percentages of volume reduction was compared using Student's t-test and the existence of significant difference between the groups for cases with ≤50% or > 50% lesion volume reduction was assessed by chi-squared test ratio likelihood test (α = 5%).

The volume reduction was greater in GTS (79.25%) than GSS (68.35%), though without significant difference (p > 0.05). After 12 months, complete repair was not observed in any specimen. Lesion volume reduction > 50% was significantly greater with the use of an intracanal medication (p < 0.05).

Twelve months posttreatment, CBCT did not show complete repair in any of the teeth, suggesting that this follow-up period is not sufficient for complete lesion regression. In both groups, similar AP lesion volume reduction was observed after 12 months, with a more advanced repair (> 50% volume reduction) in the teeth medicated with calcium hydroxide intracanal dressing.

Calcium hydroxide intracanal dressing provided clinical evidence to indicate its use in teeth with apical periodontitis prior to definitive root canal filling.

de Castro Rizzi-Maia C, Maia-Filho EM, Nelson-Filho P, Segato RAB, de Queiroz AM, Paula-Silva FWG, da Silva Pereira SM, Borges AH, da Silva LAB. Single vs Twosession Root Canal Treatment: A Preliminary Randomized Clinical Study using Cone Beam Computed Tomography. J Contemp Dent Pract 2016;17(7):515-521.