An evaluation of factors associated with persistent primary teeth.

The aim of the present study was to investigate the reasons for the persistence of primary teeth and also use panoramic radiography to determine the characteristics of persistence teeth. Four-hundred and twenty-six panoramic radiographies, which diagnosed one or more retained primary teeth, were selected from 100,577 panoramic radiographic image files from nine clinics and six different cities in Turkey. The selected radiographies were evaluated to determine the reasons for the persistence of primary teeth; furthermore, this study analyzed the characteristics of the retained primary teeth including tooth type, number, location, and root resorption, and whether, or not, the primary teeth showed evidence of pathological conditions, such as periodontal problems, caries, ankylosis, infra-occlusions, or tipping of the adjacent permanent teeth. Six hundred and seventy-seven retained primary teeth were determined in 426 patients (148 males and 278 females). Retained primary teeth were found most frequently in the mandible rather than the maxilla and the left side was more frequently affected than the right side. Level 1 was found as a most frequently encountered root resorption level. Within the limitation of the present study, the most common type of persistent primary teeth seen on the dental arch were mandibular primary second molars, followed by maxillary primary canines. The most frequent reason for the persistence was the congenital absence of successors to the primary teeth, followed by impaction of the successor teeth.