The effects of superficial roughness and design on the primary stability of dental implants.
BACKGROUND
Primary implant stability has been used as an indicator for future osseointegration and whether an immediate/early loading protocol should be applied. Implant stability is the key to clinical success.


OBJECTIVE
The aim of this work was to analyze the influence of the design and surface morphology on the primary stability of dental implants. The insertion torque and resonance frequency analysis (RFA) were the parameters used to measure the primary stability of the implants.


METHODS
Thirty implants, divided in six groups of five samples were placed in cylinder of high molecular weight polyethylene. The groups were different upon two designs (cylindrical and conic) and three implant surfaces finishing (machined, acid etched, and anodized). The insertion torque was quantified by a digital torque driver (Lutron Electronic Enterprise Co., Taipei, Taiwan) and the resonance frequency was measured by Osstell mentor™ (Integration Diagnostics AB, Göteborg, Sweden). The implant surface morphology was characterized by scanning electron microscopy, roughness measurement, and friction coefficient.


RESULTS
The machined implants showed smaller insertion torques than treated implant surfaces. There were no differences between the RFA measurements in all tested surfaces. Statistical analyses demonstrated no correlation between the dental implant insertion torque and primary stability measured by the RFA. The implants with treated surfaces showed greater roughness, a higher friction coefficient, and demanded a larger insertion torque than machined implants. The results of the surface roughness and friction coefficients are in accordance with the results of the insertion torque. The difference, across the insertion torque values, between conical and cylindrical implants, can be explained by the different contact surface area among the thread geometry of these implants.


CONCLUSIONS
The maximum implant insertion torque depends on the implant geometry, thread form, and implant surface morphology. The placement of conical implants with treated surfaces required the highest insertion torque. There was no correlation between RFA and insertion torque implant.
Dos Santos
Mychelle Vianna
MV
Biomaterials Laboratory, Instituto Militar de Engenharia, Rio de Janeiro, RJ, Brazil.
Elias
Carlos Nelson
CN
Cavalcanti Lima
Jose Henrique
JH
D000134:Acid Etching, Dental; D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D003799:Dental Stress Analysis; D017276:Friction; D006244:Hardness; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium; D019415:Torque; D014732:Vibration
D020099:Coated Materials, Biocompatible; D015921:Dental Implants; D014025:Titanium