Mechanics of the taper integrated screwed-in (TIS) abutments used in dental implants

Abstract

The tapered implant-abutment interface is becoming more popular due to the mechanical reliability of retention it provides. Consequently, understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. This paper focuses on the tapered implant-abutment interface with a screw integrated at the bottom of the abutment. The tightening and loosening torques are the main factors in determining the reliability and the stability of the attachment.Analytical formulas are developed to predict tightening and loosening torque values by combining the equations related to the tapered interface with screw mechanics equations.This enables the identification of the effects of the parameters such as friction, geometric properties of the screw, the taper angle, and the elastic properties of the materials on the mecha nics of the system. In particular, a relation between the tightening torque and the screw pretension is identified. It was shown that the loosening torque is smaller than the tightening torque for typical values of the parameters. Most of the tightening lo ad is carried by the tapered section of the abutment, and in certain combinations of the parameters the pretension in the screw may become zero. The calculations performed to determine the loosening torque as a percentage of tightening torque resulted in the range 85-137%, depending on the values of taper angle and the friction coefficient.

An Overview Regarding Contemporary Biomechanical Aspects on Immediate Loading Dental Implants

“…Another approach is to use a screw with a relatively large tapered end; the term taper integrated screwed-in (TIS) abutment is used to indicate an abutment, which uses simultaneously a screw and a tapered fit. A tapered interference fit (TIF) between the abutment and the implant is also used in some implant systems to provide the connection (Bozkaya & Muftu, 2005). For the systems using a screw, the connection between the implant and the abutment depends on the screw-preload, which is generated by applying a predetermined amount of torque during installation (Bozkaya & Muftu 2003).…”

Analysis of resistance to fatigue between straight solid and anatomic abutments of Morse taper system

“…An internal conical connection (Morse taper) is an alternative to internal and external hex connections. Overlaying the components leads to a better fit between the parts and leaves a smaller gap, which in turn influences bacterial infiltration, reduces bone loss, improves stability and reduces loosening of the abutment 6,7 .…”

Análise da resistência à fratura entre pilares retos e angulados do sistema cone Morse

“…A conexão cone Morse representa atualmente uma alternativa às conexões hexagonais internas e externas 9 . Através da sobreposição dos componentes do sistema implante-pilar, tal conexão ocasiona melhor ajuste entre as partes, proporcionando menor fenda (gap) e, consequentemente, influenciando a infiltração bacteriana; além disso, minimiza o afrouxamento do pilar e melhora a estabilidade mecânica, diminuindo a reabsorção óssea peri-implantar 10,11 .…”