Epithelial remnants in the crestal periodontium of the deciduous and permanent dentition of beagle dogs
Epithelial remnants in the crestal periodontium (EPRs) are a part of periodontal tissues of man and persist throughout life. The purpose of this animal study was to document and characterize EPRs of crestal periodontium of the deciduous dentition of a diphyodont and compare them with EPR units found in the corresponding area of the permanent dentition. Seven beagle dogs were used for the present study. At the age of 10 weeks (deciduous dentition of a diphyodont) and 15 months (permanent dentition), respectively, a six-week plaque-control period was initiated. At the end of each plaque-control period, biopsies were taken from the mandibular, P2, P3 (deciduous dentition) and P3, P4, (permanent dentition) premolar regions and prepared for histologic analysis. Three sections from each tooth unit, representing the central portion of the root, were selected for investigation. The region analyzed was divided into two subregions: the periodontal ligament region and the supracrestal region. EPR frequency, size, root distance, bone distance, and cell area were determined in the PDL region. The supracrestal region was subdivided into four equal compartments.
Results show that EPR units were distributed uniformly throughout the supracrestal and the coronal periodontal ligament connective tissue of all regions for both dentitions. Most of the remnants were of spherical shape. No EPR were seen in contact with the root surface nor found incorporated in the bone marrow spaces. Conclusions are that EPR are normal structures of the periodontium in the beagle dogs in the deciduous dentition and they appear to be similar to those found in the deciduous dentition and they appear to be similar to those found in the permanent dentition of young dogs. [M.O.]
Sterrett, J.D., T. Berglundh, and J. Lindhe, J Clin Periodont, 21:621, 1994