Corono-Radicular Grooves in a Large Sample of Human Maxillary Incisors

Abstract

Corono-radicular grooves (CRGs) are developmental anomalies on maxillary incisor teeth that have both anthropological and clinical significance. Their reported prevalence varies from around 2% in modern Caucasoid populations to 18% in Chinese, although methods of classification have differed between studies. The aim of this study was to determine the frequency of occurrence and configuration of these grooves in a large sample of Caucasoid extracted permanent maxillary incisors collected in South Australia during the early 1900s (The Ramsey Smith Collection). A total of 1481 permanent maxillary incisors was examined using a dissecting microscope and classified according to tooth type and side. CRGs were scored according to their location, length, and depth. They were observed in 78 teeth (5.3%), with three teeth displaying two grooves. No significant difference in frequency occurred between central (4.7%) and lateral (5.7%) incisors, nor between right and left sides. Most of the CRGs (51.8%) were located in the mid-palatal region of tooth crowns, originating from the cingulum and terminating on the root surface less than 5.0 mm from the cemento-enamel junction (CEJ). All CRGs were less than 1.0 mm in depth. A higher proportion of CRGs was observed on the distal surface of lateral incisors (28.6%) than central incisors (9.4%). The frequency of occurrence of CRGs recorded in this study was higher than that of some previous reports, although the possibility of sampling bias in collections of extracted teeth needs to be taken into account. The relatively high frequency of CRGs on the distal surface of maxillary lateral incisors has important clinical implications, as plaque accumulation and loss of gingival attachment in this region may lead to severe localized periodontal involvement.