In Vitro Evaluation of Manual Torque Values Applied to Implant-Abutment Complex by Different Clinicians and Abutment Screw Loosening

Abstract

Preload is applied to screws manually or using a torque wrench in dental implant systems, and the preload applied must be appropriate for the purpose. The aim of this study was to assess screw loosening and bending/torsional moments applied by clinicians of various specialties following application of manual tightening torque to combinations of implants and abutments. Ten-millimeter implants of 3.7 and 4.1 mm diameters and standard or solid abutments were used. Each group contained five implant-abutment combinations. The control and experimental groups comprised 20 and 160 specimens, respectively. Implants in the experimental group were tightened by dentists of different specialties. Torsional and bending moments during tightening were measured using a strain gauge. Control group and implants with preload values close to the ideal preload were subjected to a dynamic loading test at 150 N, 15 Hz, and 85,000 cycles. The implants that deformed in this test were examined using an optical microscope to assess deformities. Manual tightening did not yield the manufacturer-recommended preload values. Dynamic loading testing suggested early screw loosening/fracture in samples with insufficient preload.

The Accuracy of New and Aged Mechanical Torque Devices Employed in Five Dental Implant Systems

“…In this situation, the surface connection between the implant and abutment is lost, leading to the exertion of abnormally directed forces to the screw. These phenomena cause complications, such as inflammation/infection of the soft tissues and fracture of the screw [ 11 ]. As hand-held drivers do not adequately tighten abutments, the use of mechanical torque-limiting devices has become standard [ 12 ].…”

“…As hand-held drivers do not adequately tighten abutments, the use of mechanical torque-limiting devices has become standard [ 12 ]. Application of the optimum torsional force to the implant–abutment connection, ideally using a torque-calibrated ratchet wrench, is crucial [ 11 ].…”

Avaliação da plataforma tri-channel por meio de microtomografia computadorizada e suas propriedades mecânicas após torque de inserção, fadiga e fratura

“…Para justificar tais achados, é necessário discorrer a respeito da perda de torque (afrouxamento). A literatura é vasta e demonstra que é uma das complicações mecânicas mais frequentes clinicamente (Dincer Kose et al, 2017;Ha et al, 2011;Tsuge, Hagiwara, 2009). Além disso, é parâmetro importante para o reconhecimento de problemas no quesito biomecânico ou em eventuais parafunções (Winkler et al, 2003).…”

“…Quando em posição, ao conjunto implante/pilar/parafuso é aplicada uma força denominada pré-carga, cujo objetivo principal é manter estável todo o sistema; tal força é essencialmente axial e incide ao longo do parafuso, segundo limites de deformação elástica do material -aproximadamente 75% do limite de proporcionalidade (Coppedê et al, 2009). Em geral, tem-se que, quanto maior a précarga, mais estabilidade haverá na conexão entre implante e componentes protéticos (Dincer Kose et al, 2017).…”

“…Consequentemente, ao se comparar o torque inicial com o final, há redução de força, via resistência à fricção do conjunto (Dincer Kose et al, 2017).…”