Influence of mini-screw diameter and loading conditions on static and dynamic assessments of
bone-implant contact: An animal study.
Orthod Craniofac Res 2019;
22 Suppl 1:96-100. [PMID:
31074154 DOI:
10.1111/ocr.12293]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 01/16/2019] [Indexed: 11/29/2022]
Abstract
OBJECTIVES
The goal was to compare static versus dynamic bone-implant interface histology of mini-screws and to evaluate its relation to diameter and load.
SETTING AND SAMPLE POPULATION
Canine animal model.
MATERIAL AND METHODS
Custom-machined, titanium alloy (Ti6AI4V) mini-screws (n = 70) of 1.60, 2.00, 3.00 and 3.75 mm diameter were placed into edentulous sites in five skeletally mature beagle dogs. Using a split-mouth design, no load (NL) was applied to one side while a 2N load (L) was applied by calibrated coil springs on the other side. Intravenous bone labels were administered 21 and 7 days prior to sacrifice. Dogs were euthanized 90 days after screw placement. Bone sections were analysed under bright-field and epifluorescent light. The region of interest was defined as the bone within the threads of the screws. The following parameters were quantified: (a) Static-bone volume/tissue volume (BV/TV %) and bone-implant contact (BIC, %); (b) Dynamic-labelled bone/bone volume (LB/BV, %), and dynamic BIC (DBIC, %).
RESULTS
BV/TV ranged from 71.2% to 85.0% of the screw surface. BIC ranged from 45.7% to 55.4% of the screw surface and was not affected by diameter (P = 0.66). In contrast, the percentage of DBIC did not vary with the applied load (P = 0.41); however, it correlated significantly with the diameter of the screw (P = 0.001).
CONCLUSION
The percentage of DBIC that is actively remodelling increases with increasing diameter of the screw. Dynamic histomorphometry is more sensitive to detecting changes in bone-implant contact when compared to static measurements.
Collapse