The prevalence, location and conformation of palato-radicular grooves in maxillary incisors.

Palato-radicular grooves in maxillary lateral incisors have been implicated as an initiating factor in localized gingivitis and periodontitis. Focal loss of periodontal attachment associated with these grooves, some of which may extend to the apical third of the root, could result in a hopeless prognosis for tooth retention. There is disagreement as to the prevalence of this anomaly. As well, little is known about the shape, location and length of the defect. This study examined 3168 extracted maxillary lateral and central incisors. Of these teeth 4.6% had a palato-radicular groove. About half of the grooves terminated on the root and 58% of these extended more than 5 mm from the cementoenamel junction. A poorly described deformity, displacement of the cementoenamel junction, occurred in 38% of the grooves which crossed that structure. Although an extension of enamel in the groove has been suggested as a possible factor in the progression of localized periodontal disease, its presence was rarely observed.