Periodontal inflammation triggers a site‐specific and wide radius of calcium metabolic effects on alveolar bone

Abstract

Background and Objective There is a close relationship between inflammation and bone remodeling in the periodontium. However, previous studies have not delineated the alterations in calcium (Ca) metabolism during periodontitis progression. The aim of this current investigation was to examine Ca dynamics in alveolar bone of rats during progression of ligature‐induced periodontal inflammation by using 45Ca, which is an index of hard tissue neogenesis. Material and Methods To induce periodontitis, the maxillary right first molar (M1) of 8‐week‐old male rats was ligated with a silk suture for 1, 3, 7, and 28 days. The left M1 was not ligated as a control. To evaluate resultant changes in bone neogenesis, 45CaCl2 was injected intraperitoneally 24 hours before euthanasia. The left‐and‐right palatal mucosa, molar teeth (M1 and M2), and alveolar bone were harvested for evaluation of 45Ca radioactivity using a liquid scintillation counter. The distribution of 45Ca in maxillary tissues was evaluated using autoradiography (ARG). In addition, we analyzed the bone volume fraction (BV/TV) and bone mineral density (BMD) of the alveolar bone by micro‐computed tomography. To investigate the number of osteoclasts and osteoblasts, tartrate‐resistant acid phosphatase (TRAP) and bone‐specific alkaline phosphatase (BAP) were measured by an enzymatic assay and immunohistochemistry, respectively. Results 45Ca radioactivity in the alveolar bone of the ligature side decreased by 8% compared to the unligated control‐side on day 1, whereas on day 7, it markedly increased by 33%. The 45Ca levels in the gingival tissue and molar teeth were slightly but significantly lower than the control‐side on day 1 and higher from day 3 to 28. The variation in 45Ca levels for the alveolar bone was greater and specific compared with other tissues. Furthermore, on day 7, ARG data revealed that 45Ca on the control side was primarily localized to the periodontal ligament (PDL) space and alveolar bone crest and barely detected in the gingival tissues and deeper parts of the alveolar bone. On the ligature side, 45Ca disappeared from the PDL and alveolar crest, but instead was broadly and significantly increased within the deeper zones of the alveolar bone and furcation areas and distant from the site of ligature placement and periodontal inflammation. In the shallow zone of the alveolar bone, these changes in 45Ca levels on day 7 were consistent with decreases in the bone structural parameters (BV/TV and BMD), enhanced osteoclast presence, and suppressed levels of BAP expression in osteoblasts. In contrast, the deep zone and furcation area showed that TRAP‐positive cells increased, but BAP expression was maintained in the resorption lacunae of the alveolar bone. Conclusion During periodontitis progression in rats, 45Ca levels in the alveolar bone exhibited biphasic alterations, namely decreases and increases. These data indicate that periodontitis induces a wide range of site‐specific Ca metabolism alterations within the alveolar bone.

Wound healing in periodontal disease induces macrophage polarization characterized by different arginine‐metabolizing enzymes

“…In our previous study using a ligature‐induced periodontitis rat model, we observed increased inflammatory cell infiltration and decreased bone density after 7 days of ligation compared with the control group before ligation 24,37,38 . Spolidorio et al 22 removed the ligature on rat molars 7 days after placement and reported significant recovery of periodontal tissue 8 days later.…”

“…The mean of these three points was used as the representative measurement for each mouse (Figure 2A). In addition, the bone volume fraction (BV/TV) and bone mineral density (BMD) of the alveolar bone were measured within a region of interest (ROI) normalized to the following anatomic indices 23,24 : horizontal section, 300 μm in vertical diameter from 150 μm lateral to the root apex from the CEJ of the second molar; sagittal section, 1,000 μm in proximal diameter from the proximal surface of the third molar; and anterior section, 800 μm in buccal diameter from the palatal root bone wall of the second molar. The total volume of the ROI was 300 × 1000 × 800 μm 3 .…”

Deuterohemin-Ala-His-Thr-Val-Glu-Lys (DhHP-6) Mimicking Enzyme as Synergistic Antioxidant and Anti-Inflammatory Material for Periodontitis Therapy

“…Micro-CT analysis of the protective effect of DhHP-6 rats on alveolar bone resorption. To evaluate the effect of DhHP-6 on alveolar bone resorption in rats with periodontitis, we used micro-CT scanning to compare alveolar bone loss and bone structure parameters of the left maxillary first molar of each group of rats [ 33 ]. A 3D reconstruction of the left maxillary of the rats revealed that alveolar bone resorption was obvious in the periodontitis group and the low-dose DhHP-6 group.…”

Genetic analysis of impaired healing responses after periodontal therapy in type 2 diabetes: Clinical and in vivo studies

“…Both oral microbiome alterations and physical stimuli by ligation involve the induction of periodontal tissue inflammation 38,39 . In this model, significant inflammation is well‐established at 7 days after ligature placement, 40–42 and the ligation‐induced periodontal tissue destruction reaches an approximate plateau after 14 days 20 . This experimental model can be also used to observe periodontal tissue healing after ligature removal because tissue attachment recovers with the disappearance of inflammation after ligature removal 24 .…”