Influence of Apical Diameter on the Outcome of Regenerative Endodontic Treatment in Teeth with Pulp Necrosis: A Review.

INTRODUCTION: The aim of this review was to evaluate whether the apical diameter of teeth with necrotic pulp affects the outcomes of regenerative endodontic treatment and to determine the minimal apical size needed to obtain proper pulp revascularization. METHODS: A literature search was performed from January 1, 2001, to November 25, 2016. Studies that satisfied the inclusion criteria were subjected to data extraction and analysis. RESULTS: In total, 14 studies with 85 patients were included. There were 10 case reports, 3 case series, and 1 prospective cohort study. The apical diameters of the teeth were divided into 3 groups: a narrow-sized group (group N), <0.5 mm (n = 10); a medium-sized group (group M), 0.5-1.0 mm (n = 25); and a wide-sized group (group W), >1.0 mm (n = 60). In group N, 1 tooth failed, 2 teeth completely healed, and 7 teeth incompletely healed. In group M, 2 teeth were excluded, and 1 tooth failed. In group W, 3 teeth were excluded, and 4 teeth failed. The clinical success rates were 90%, 95.65%, and 92.98% in groups N, M, and W, respectively. CONCLUSIONS: Within the limitations, the teeth with apical diameters <1.0 mm achieved clinical success after regenerative endodontic treatment. Meanwhile, the teeth with apical diameters of 0.5-1.0 mm attained the highest clinical success rate, which may be related to other potential factors, including patient age, pulp necrosis etiology, preoperative apical radiolucency, procedure details, follow-up period, and sample size.