Periodontal regeneration using strontium-loaded mesoporous bioactive glass scaffolds in osteoporotic rats

Abstract

Recent studies demonstrate that the rate of periodontal breakdown significantly increased in patients compromised from both periodontal disease and osteoporosis. One pharmacological agent used for their treatment is strontium renalate due to its simultaneous ability to increase bone formation and halt bone resorption. The aim of the present study was to achieve periodontal regeneration of strontium-incorporated mesoporous bioactive glass (Sr-MBG) scaffolds in an osteoporotic animal model carried out by bilateral ovariectomy (OVX). 15 female Wistar rats were randomly assigned to three groups: control unfilled periodontal defects, 2) MBG alone and 3) Sr-MBG scaffolds. 10 weeks after OVX, bilateral fenestration defects were created at the buccal aspect of the first mandibular molar and assessed by micro-CT and histomorphometric analysis after 28 days. Periodontal fenestration defects treated with Sr-MBG scaffolds showed greater new bone formation (46.67%) when compared to MBG scaffolds (39.33%) and control unfilled samples (17.50%). The number of TRAP-positive osteoclasts was also significantly reduced in defects receiving Sr-MBG scaffolds. The results from the present study suggest that Sr-MBG scaffolds may provide greater periondontal regeneration. Clinical studies are required to fully characterize the possible beneficial effect of Sr-releasing scaffolds for patients suffering from a combination of both periodontal disease and osteoporosis.

Figure 1. Establishment of rat osteoporotic model created by OVX.

3D µ-CT images of normal bone and osteoporotic bone as well as their representative H&E staining.

Figure 2. The overall state of bone regeneration was exhibited by 3D reconstruction.

The red box represented the original extent of surgical defect in general. A, D and G: buccal view; B, E and H: screenshot in horizontal; C, F and I: screenshot in vertical. Bar: 1 mm.

Figure 3. Statistical analysis of periodontal regeneration: A) proportion of mineralized tissue from horizontal cutaway view of 3D construction, B) area of new bone from H&E stain, C) defect fill from Masson trichrome stain and D) the number of TRAP-positive cells from TRAP stain.

Results were given by mean ±SD. *: p<0.05, **: p<0.01.

Figure 4. Representative sections of H&E stain (A, C and E) revealed the osteogenesis among the defects.

New bone was visible in the area adjacent to the old bone and implanted scaffolds. Representative sections of Masson trichrome stain (B, D and F) revealed the compound of collagen in the osteogenic active zone. Bar: 200 µm. R: Root, F =  Fibroblasts, NB =  New bone, OB =  Old bone, M =  Material.

Figure 5. TRAP-staining for A) control, B) MBG alone and C) Sr-MBG scaffolds.

Positive cells were visible in the surface of bone (control, MBG and Sr-MBG) and scaffolds (MBG and Sr-MBG). Bar: 100 µm. Arrows depict areas of TRAP-staining, NB =  New bone, M =  Material.