Prevalence of impacted teeth and associated pathologies--a radiographic study of the Hong Kong Chinese population.

OBJECTIVES To investigate the prevalence and pattern of impacted teeth and associated pathologies in the Hong Kong Chinese population. SETTING The Reception and Primary Care Clinic, Prince Philip Dental Hospital, Hong Kong. DESIGN Retrospective study. SUBJECTS AND METHODS The records of 7486 patients were examined to determine whether the chief complaints were related to impacted teeth and associated pathologies, which were investigated using panoramic radiographs. RESULTS A total of 2115 (28.3%) patients presented with at least one impacted tooth. Among the 3853 impacted teeth, mandibular third molars were the most common (82.5%), followed by maxillary third molars (15.6%), and maxillary canines (0.8%). Approximately 8% of mandibular second molars associated with impacted third molars had periodontal bone loss of more than 5 mm on their distal surfaces. Caries were also found on the same surfaces in approximately 7% of the second molars. Approximately 30% of patients with dental impaction had symptoms, and 75% had complaints limited to one side of the mouth. CONCLUSIONS The prevalence of impacted teeth was high, and there was a predilection for impacted third molars in the mandible. More than 50% of maxillary third molars had erupted, creating potential trauma of the pericoronal tissues of the partially erupted mandibular third molars. Caries and periodontal diseases were commonly seen in relation to the impacted third molars, whereas cystic pathology and root resorption were rarely observed.