Characterization of root surface periodontal ligament following avulsion, severe intrusion or extraction: preliminary observations.

This study employed novel topographic and histological techniques to assess remaining periodontal ligament (PDL) in a convenience sample of avulsed and intruded human permanent incisors and extracted premolars. Seventeen human teeth (eight avulsed, five severely intruded and four uninjured extracted) were evaluated for the distribution and physical characteristics of adherent root surface PDL. The topographic distribution of PDL was assessed by staining roots with malachite green and determining the proportion of remaining PDL within selected regions on four aspects of each tooth. In order to characterize mechanical damage to PDL, serial transverse sections of roots were stained with hematoxylin and eosin and examined at magnifications of 40x to 800x. The sections were photographed and imaging software was used to calculate the percentage of remaining PDL in the circumference of each root section. Topographic analysis demonstrated that 54% of the PDL remained on roots of avulsed and severely intruded incisors and 36% of the PDL remained on the extracted single-rooted premolars. Examination of serial transverse root sections revealed that 58% of the PDL remained on roots of avulsed or severely intruded incisors and 54% on extracted premolars. Avulsed and severely intruded incisors demonstrated similar amounts of retained PDL. In both injuries, almost half of the root surface was denuded of PDL.