Histological characteristics of newly formed cementum in surgically created one-wall intrabony defect of canine model

Abstract

Periodontal regenerative therapy and tissue engineering of defects destructedby severe periodontitis are mainly focused on bone regeneration. Even thoughcementum regeneration needs more understanding, it is believed to play an importantrole in periodontal regeneration. To fully understand cementum regeneration, thecomparison of pristine cementum and repaired cementum should be clarified first.This study, using histological techniques, was designed to focus on cementumregeneration and to compare pristine cementum and repaired cementum after surgicalprocedures with 8 and 24 week period in canine models. Buccal and lingualmucoperiosteal flaps were reflected to surgically create critical-size, “box-type” (4mm wide, 5 mm depth), one-wall, intrabony defects at the distal aspect of the 2nd andthe mesial aspect of the 4th mandibular premolars in the right and left jaw quadrants.Animals were sacrificed after 8 and 24 weeks and pristine specimens from mesial sideof the 2nd mandibular premolars were compared. The results are as follows. 1.Repaired cementum is mostly composed of acellular cementum and cellular mixedfiber cementum. 2. Repaired cementum is thicker in apical area than coronal area. 3.Acellular cementum of supracrestal area appears to be amorphous. 4. Newly formedcellular cementum is partially detached from underlying circumpulpal dentin which implies weak attachment between new cementum and dentin and this split was lessobserved in 24 week group than 8 week group. 5. Vertical height of repairedcementum is increased in 24 week group compared to 8 week group. 6. The thicknessof subcrestal cementum was slightly increased in 24 week group than 8 week group.Within the limitation to this study, we could conclude that repaired cementum afterroot planing was mainly acellular cementum and cementum tissue matured to shapelike pristine cementum as healing progresses from 8 to 24 weeks.