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

Abstract

Purpose: Periodontal regenerative therapies for defects created by severe periodontitis are mainly focused on bone regeneration. Although cementum regeneration needs to be better understood, it is believed to play an important role in periodontal regeneration. The first step toward a full understanding of cementum regeneration is to compare repaired cementum to pristine cementum. This study, which used histological techniques, was designed to focus on cementum regeneration and to compare pristine cementum to repaired cementum after surgical procedures with 8 and 24 week healing periods in a canine model.

Methods: Buccal and lingual mucoperiosteal flaps of 10 beagle dogs were surgically reflected to create critical-sized defects. Intrabony one-wall defects, of which dimension is 4 mm width and 5 mm depth, were made at the distal aspect of mandibular second premolars and the mesial aspect of mandibular fourth premolars in the right and left jaw quadrants. Animals were sacrificed after 8 and 24 weeks post-surgery for histological specimen preparation and histometric analysis.

Results: The repaired cementum was composed mostly of acellular cementum and cellular mixed fiber cementum and was thicker in the apical area than in the coronal area. The acellular cementum of the supracrestal area appeared to be amorphous. The newly formed cellular cementum was partially detached from the underlying circumpulpal dentin, which implied a weak attachment between new cementum and dentin, and this split was observed to a lesser extent in the 24 week group than in the 8 week group. The vertical height of the repaired cementum was greater in the 24 week group than in the 8 week group.

Conclusions: Within the limitations of this study, we can conclude that repaired cementum after root planing was mainly acellular cementum and cementum tissue that matured to a shape similar to pristine cementum as the healing progressed from 8 to 24 weeks.

Keywords: Animal models; Dental cementum; Periodontal guided tissue regeneration.

Figure 1

Surgically created, critical-size, one-wall, intrabony, periodontal defect at the distal aspect of mandibular second premolars and the mesial aspect of mandibular fourth premolars. Mucoperiosteal flaps are adapted and sutured for primary intention healing. The right panel shows healing at week 8 postsurgery.

Figure 2

Periodontal healing illustrated as a percentage of defect height after 8 weeks and 24 weeks postsurgery.

Figure 3

Mesio-distal section of a pristine specimen (H&E stain, left ×20 and right ×200).

Figure 4

Mesio-distal section of an 8 week specimen (H&E stain, left ×20 and right ×200).

Figure 5

Mesio-distal section of a 24 week specimen (H&E stain, left ×20 and right ×200).

Figure 6

Acellular cementum coverage between junctional epithelium and alveolar crest. Pristine, 8 weeks and 24 weeks (H&E stain, ×400).

Figure 7

Cellular cementum coverage over notch area (H&E stain, ×1,000). Corresponding area for notch formation is shown in pristine group. Pristine, 8 weeks and 24 weeks.