Paradental cysts: a role for food impaction in the pathogenesis? A review of cases from Northern Ireland.

We present the clinical, radiographic and histological findings of 15 paradental cysts. These were the second most common type of cyst associated with mandibular third molars, comprising 25% of all lesions at this site. Ten patients were aged 30 years or younger and 13 gave a history of pericoronitis. There was a close relationship between the site of the cyst and the angle of the impacted tooth; the cyst lay mesially to two mesioangularly impacted teeth, buccal to two vertically impacted teeth and distal/distobuccal to the remainder, all but one of which were distoangular in impaction. The pericoronal follicular space was preserved in nine cases, a useful diagnostic sign. Most cysts were lined with epithelium that resembled that seen in radicular cysts, although the lining of three cysts resembled that of unicystic ameloblastoma, a potential diagnostic pitfall. We propose that the relation between location of cyst and angle of impaction points to a role for food impaction in the pathogenesis of paradental cysts.