Bone remodeling surrounding primary teeth in skeletally immature dogs

Abstract

Objective: To quantify remodeling in the bone surrounding fully erupted primary teeth and to compare bone remodeling in the primary and permanent dentitions.

Materials and methods: Two bone sections were obtained bilaterally from the maxilla and mandible of the primary molar region of approximately 5-month-old male beagle dogs. Histomorphometric methods were used to estimate the osteonal remodeling in the alveolar and basal regions of the tooth supporting bone. The following variables were calculated: mineral apposition rate (MAR, µm/d), mineralizing surface/bone surface (MS/BS, %), bone formation rate (BFR, %/y), and erosion surface/bone surface (ES/BS, %). Comparisons were made between jaws (maxilla vs mandible) and bone types (alveolar vs basal), and data analyzed by analysis of variance (ANOVA) and Tukey-Kramer tests. Remodeling (BFR) surrounding primary teeth was compared to existing data from bone surrounding permanent teeth.

Results: The mean and standard deviation BFR values (%/y) were as follows: mandibular alveolar, 44.10 (±26.89); maxillary alveolar, 3.54 (±3.57); mandibular basal, 22.65 (±14.65); and maxillary basal, 12.33 (±7.11). The mandibular BFR was significantly (P < .05) higher than the maxillary bone. The BFR of the alveolar bone of primary teeth was not significantly (P = .48) different from the alveolar bone supporting permanent teeth.

Conclusions: The remodeling rate of alveolar bone in skeletally immature dogs was greater in the mandible than in the maxilla and remained unaltered between primary and permanent dentitions.

Figure 1

Composite epifluorescent photomicrographs (each taken at magnification 12.5×) from skeletally immature (approximately 5-month-old) dog illustrating bone formation in the (A) mandible and (B) maxilla, surrounding a portion of the primary tooth (P) and developing permanent tooth (∗). In Figure 1A, remodeling (R) is apparent in the alveolar and basal bone, and modeling (M) is seen near the apex of the primary tooth in (A) and buccal (B)/lingual (L) surfaces. The primary tooth root apex indicated the approximate anatomically separation of alveolar (A) and basal (Ba) bone. In Figure 1B, A indicates the alveolar region, and B indicates basal regions.

Figure 2

Epifluorescent photomicrograph (total magnification 40×) from the skeletally immature mandibular alveolar bone (same specimen as Figure 1A) demonstrating areas of modeling (M) and remodeling (R).

Figure 3

Epifluorescent photomicrographs (total magnification 100×) from the skeletally immature mandibular basal bone demonstrating intracortical bone with remodeling (R) and multiple secondary osteons (example in the white rectangle), with a portion of modeling bone included for comparison (M) and separated by the solid lines. Area of neurovascular bundle (∗).

Figure 4

Epifluorescent photomicrograph (same specimen as Figure 1A) (total magnification 100×) of skeletally immature mandibular alveolar bone demonstrating erosion cavities (E) and partial erosion cavities (PE). PDL indicates periodontal ligament.