Will Topical Application of Alendronate Disodium to Dental Roots Reduce Osteoclast Adherence and Resorption in Vitro?

Abstract

Introduction: The purposes of this study were: 1. To demonstrate the presence of fully differentiated, multinucleated human osteoclasts on bovine and human dentin and cementum in vitro. 2. To comparatively quantify osteoclast presence and distribution on tooth sections and adjacent lab wells following differentiation. 3. To comparatively quantify the amount of resorption that occurs when human root sections are subjected to a bisphosphonate antiresorptive treatment in comparison to no treatment. Materials and Methods: 30 sections of human tooth root and 48 sections of bovine tooth root were created using an IsoMet saw. The tooth sections from both groups were then divided into 2 equal groups of 15 and 24 sections respectively. One group received no treatment and the second group was soaked in 2mM Alendronate Disodium prior to transfer to culture. All sections were then plated in sterile culture wells with osteoclast precursor cells derived from whole human blood. The sections remained in culture until completion of osteoclastic differentiation, which took approximately 24 days. The supernatant was recovered from each well and used in an ELISA to determine the CTX-1 breakdown products from each section. The sections were fixed in paraformaldehyde and TRAP stained for visualization of osteoclasts. TRAP+ cell counts were performed on tooth sections and residual treatment wells. Student t-tests were used to determine differences between groups Results: Osteoclast attachment was observed on all human and bovine samples with the exception of one bacterially contaminated sample. The no treatment group had significantly more TRAP+ cells than the ALN group on both the human and bovine tooth sections. The no treatment group also had significantly more cells per residual well than the ALN group. No evidence of osteoclastic resorption could be demonstrated with the ELISA. Conclusions: Within the limitations of this study, it can be concluded that: 1. Fully differentiated, multinucleated osteoclasts can be successfully isolated from whole human blood and seeded onto human tooth sections in vitro. 2. Topical application of ALN disodium to extracted and sectioned tooth surfaces suppresses osteoclastic proliferation and differentiation in vitro. 3. Bovine teeth and human teeth allow for similar human osteoclast attachment and distribution in an in vitro model. 4. Mononuclear osteoclasts do not exhibit appreciable resorptive potential on sectioned surfaces in vitro.