EPITHELIAL REMNANTS IN THE CRESTAL PERIODONTIUM OF THE DECIDUOUS AND PERMANENT DENTITION OF BEAGLE DOGS

The purpose of this study was to document and characterize epithelial remnants (EPRs) of the crestal periodontium of the deciduous dentition of a diphyodont and compare them with EPR units found in the correspo nding area of the permanent dentition. 7 beagle dogs were used. At the age of 10 weeks (deciduous dentition) and 15 months (permanent dentit ion), respectively, a 6-week plaque control period was initiated. At t he end of each plaque control period, biopsies were obtained from the mandibular P-02, P-03 (deciduous dentition) and P-3, P-4 (permanent de ntition) premolar regions and prepared for histologic analysis. 2 regi ons, (1) the supracrestal region and (2) the periodontal ligament regi on, were identified. The supracrestal region was divided into 4 compar tments of equal height. The histologic parameters studied included the (i) EPR frequency: number of EPRs/mm of root length, (ii) EPR size, ( iii) EPR-root distance, (iv) EPR-bone distance and (v) cell area. No d ifferences were observed between the 2 dentitions with respect to the number, size and relative location of EPR units in the supracrestal re gions or the periodontal ligament regions. Epithelial remnants of the supracrestal region in both dentitions tended to be more frequent, lar ger and positioned further from the root surface than the EPRs of the periodontal ligament region. EPR units of the periodontal ligament reg ion were located significantly further from the bone in the deciduous dentition than in the permanent dentition. The cell area of EPRs did n ot differ between the 2 dentitions. It was concluded that EPRs are a n ormal component of the crestal periodontal tissues of the deciduous de ntitions of the diphyodont beagle dog and they appear to be similar to those found in the permanent dentition of young dogs.