Bone Density and Implant Primary Stability. A Study on Equine Bone Blocks.

Francesco Orlando,Paolo Arosio,Danilo Alessio Di Stefano,Federico Arosio

doi:10.3390/dj7030073

Abstract

Previous results on synthetic blocks mimicking bone indicate that bone density can be measured by the friction encountered by a rotating probe while it descends into bone, and that primary implant stability may be measured through the integral (I) of the torque–depth curve at implant insertion. This study aims to repeat those tests on collagen-preserving equine bone blocks as they better reproduce the mechanical properties of natural bone. Fifteen cancellous equine blocks had their density measured using a measuring probe. This was compared to their known physical density through linear regression analysis. Implant placement was carried out into six cancellous equine blocks and primary stability was measured using (I), as well as the insertion torque (IT), the implant stability quotient (ISQ), and the reverse torque (RT). The relation between (I), (IT), (ISQ), and (RT) was investigated by correlation analysis. Bone density measured using the probe correlated significantly with actual density, both with (r = 0.764) and without irrigation (r = 0.977). (I) correlated significantly with IT and RT under all irrigation conditions, and with ISQ only without irrigation (r = 0.886). The results suggest that the probe provides actual bone density measurements. They also indicate that (I) measures primary implant stability and is more sensitive to density variations than IT, RT, and ISQ. Results are consistent with those obtained on synthetic blocks but suggest that equine bone blocks may better reproduce the mechanical properties of human cancellous alveolar bone. This should be the subject of additional studies.

Highlights

Bone density is one of the main factors determining implant stability [1,2]
Previous results on synthetic blocks mimicking bone indicate that bone density can be measured by the friction encountered by a rotating probe while it descends into bone, and that primary implant stability may be measured through the integral (I) of the torque–depth curve at implant insertion
Results are consistent with those obtained on synthetic blocks but suggest that equine bone blocks may better reproduce the mechanical properties of human cancellous alveolar bone

Summary

Introduction

Bone density is one of the main factors determining implant stability [1,2]. This, in turn, determines successful osseointegration [3]. Displays significantly different anatomical features than cancellous bone, namely no trabecular spaces, which are replaced by a dense matrix made of mineralized collagen fibers [8]. This gives cortical bone significantly different mechanical properties: cortical bone has a greater density, compressive strength and stiffness [7,8,9,10]. When a dense a thick cortical bone layer is present at the implant insertion site, according to the position in the jaw [12], it may be exploited by the oral surgeon to give the implant additional primary stability, especially when trabecular bone has a low density. The implant head, may engage the cortical bone layer to an extent that depends on the implant site underpreparation [13,14,15]

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