The aim of the present study was to determine on panoramic radiographic images the effect of the distance between the root curvatures and inferior alveolar canal (IAC) root tip overlap on the surgeon's risk assessment predicting inferior alveolar nerve (IAN) paresthesia after lower third molar removal. In this case-control study 41 cases with postoperative IAN paresthesia and 359 controls without any postoperative complications were involved. Demographic data, root curvatures and the extent of IAC-root tip overlap were registered. The cases of major curvature--larger than 90 degrees (P=0.015; odds ratio [OR]=2.65), the "deepest" superimposition (P<0.001; OR=1.96), female gender (P=0.020) and increased age (P=0.008) were significantly associated with IAN paresthesia. Assessing root curvatures and the extent of IAC-root tip overlap for predicting IAN paresthesia after mandibular third molar removal should help to improve risk assessment.