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Updated: Apr 21, 2026
An Improved Mechanical Testing Method to Assess Bone-implant Anchorage
Published on: February 10, 2014
Surface microtexture and hydroxyapatite coating integrity of titanium dental implants following clinically relevant
Mahmoud Elkahly1, Mohamed Elshewy1, Rafael Rocha Pacheco1
1Department of Restorative Sciences, Dental College of Georgia, Augusta University, Augusta, Georgia, USA.
Purpose:
To evaluate the effect of clinically relevant insertion torque on implant surface microtexture, hydroxyapatite coating integrity, and material transfer following single-direction torsional insertion of titanium dental implants.
Materials And Methods:
Nanohydroxyapatite-coated, cold-worked commercially pure Grade 4 titanium implants were inserted into standardized polyurethane bone analogs at target torques of 30, 60, and 80 Ncm. As-manufactured implants served as controls. Surface alterations were evaluated using scanning electron microscopy (SEM) across defined implant regions. Quantitative surface texture changes were assessed using gray-level co-occurrence matrix (GLCM) analysis. Energy-dispersive spectroscopy (EDS) was used to assess changes in surface chemistry and detect material transfer to the surrounding substrate. Macroscopic coating loss was quantified using standardized photographic analysis.
Results:
Implants inserted at 30 Ncm exhibited limited and localized surface wear, with most of the nanohydroxyapatite coating preserved. At 60 Ncm, coating loss became substantial, accompanied by surface smoothing and longitudinal striations oriented parallel to the direction of rotation. At 80 Ncm, extensive coating delamination, deep abrasion marks, and particulate debris were observed across multiple implant regions. GLCM analysis demonstrated a torque-dependent reduction in surface roughness and complexity. EDS revealed progressive loss of nanohydroxyapatite-associated elements on implant surfaces and increased detection of titanium and calcium within the surrounding substrate at higher torque levels.
Conclusions:
Within the limitations of this in vitro study and the specific implant system evaluated, increasing insertion torque produced progressive, torque-dependent degradation of implant surface microtexture and nanohydroxyapatite coating integrity, with corresponding evidence of material transfer to the surrounding substrate. Surface changes were limited at 30 Ncm but became substantial at 60 Ncm and extensive at 80 Ncm, despite no gross macroscopic deformation. These findings suggest that higher insertion torques may compromise engineered surface features intended to support early osseointegration and reinforce the clinical value of controlled insertion torque that prioritizes both mechanical stability and surface preservation.
