[Shiau-ROC TAIWAN-O-2] Effect of mechanical loading on peri-implant bone quality in ovariectomized rat maxillae under Bisphosphonate Therapy
[Abstract]
[Objective]
As dental implant prosthetic rehabilitation becomes more prevalent among elderly populations, its long-term outcomes in osteoporotic patients undergoing anti-resorptive agent therapy remain elusive, where MRONJ poses a potential risk. This emphasizes the need for a better understanding of how bones respond to functional loading in systemic conditions, aligning with the latest NIH definition of bone quality. This study aimed to investigate the effect of repetitive mechanical loading on bone quantity and quality around implants in a rat model of osteoporotic-like condition receiving bisphosphonate (BP) medication.
[Method]
The osteoporotic-like condition was induced with bilateral ovariectomy (OVX) in nine female Wistar rats. Three months post-OVX, alendronate (0.14mg/kg) was administrated twice per week subcutaneously until the endpoint. A month after BP administration, grade IV titanium implants were placed bilaterally at the healed extraction site of the maxillary first molars. These healed implant sites were randomly divided into the control and the test groups (designated as non-load and load groups, respectively). Four weeks post-implantation, the test group received a controlled mechanical loading (10N, 3Hz, 1800 cycles, 2 days/week) via the implants for 2 weeks. The maxilla and long bone were dissected and processed for microcomputed tomography (microCT) and histomorphometric analyses. Statistical analyses were performed with the Shapiro-Wilk test to evaluate normality followed by independent t-test and Mann-Whitney U test for parametric and non-parametric data, respectively.
[Results and Discussion]
From microCT analyses, the tibia exhibited significant differences (p-value < 0.05) in most bone remodeling parameters between the BP-treated group and the no-drug control group, whereas peri-implant bone demonstrated non-significant differences among the non-load and load groups. From the histological analysis of peri-implant bone, load group had higher osteocyte density than non-load group. Moreover, load group exhibited a lower number of osteoclast number per bone surface (p <0.04). There were significant differences among the groups’ collagen composition. Load group demonstrated a higher percentage of Type I collagen while more Type III collagen was noted in non-load group. These findings strongly suggest that mechanical loading induces cellular and architectural adaptations which contribute to better bone strength in osteoporotic peri-implant bone under BP therapy.
[Objective]
As dental implant prosthetic rehabilitation becomes more prevalent among elderly populations, its long-term outcomes in osteoporotic patients undergoing anti-resorptive agent therapy remain elusive, where MRONJ poses a potential risk. This emphasizes the need for a better understanding of how bones respond to functional loading in systemic conditions, aligning with the latest NIH definition of bone quality. This study aimed to investigate the effect of repetitive mechanical loading on bone quantity and quality around implants in a rat model of osteoporotic-like condition receiving bisphosphonate (BP) medication.
[Method]
The osteoporotic-like condition was induced with bilateral ovariectomy (OVX) in nine female Wistar rats. Three months post-OVX, alendronate (0.14mg/kg) was administrated twice per week subcutaneously until the endpoint. A month after BP administration, grade IV titanium implants were placed bilaterally at the healed extraction site of the maxillary first molars. These healed implant sites were randomly divided into the control and the test groups (designated as non-load and load groups, respectively). Four weeks post-implantation, the test group received a controlled mechanical loading (10N, 3Hz, 1800 cycles, 2 days/week) via the implants for 2 weeks. The maxilla and long bone were dissected and processed for microcomputed tomography (microCT) and histomorphometric analyses. Statistical analyses were performed with the Shapiro-Wilk test to evaluate normality followed by independent t-test and Mann-Whitney U test for parametric and non-parametric data, respectively.
[Results and Discussion]
From microCT analyses, the tibia exhibited significant differences (p-value < 0.05) in most bone remodeling parameters between the BP-treated group and the no-drug control group, whereas peri-implant bone demonstrated non-significant differences among the non-load and load groups. From the histological analysis of peri-implant bone, load group had higher osteocyte density than non-load group. Moreover, load group exhibited a lower number of osteoclast number per bone surface (p <0.04). There were significant differences among the groups’ collagen composition. Load group demonstrated a higher percentage of Type I collagen while more Type III collagen was noted in non-load group. These findings strongly suggest that mechanical loading induces cellular and architectural adaptations which contribute to better bone strength in osteoporotic peri-implant bone under BP therapy.