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Monday, September 22, 2008: 11:45 AM
Room C (Palazzo dei Congressi di Stresa)
Rotary endodontic instruments are used in dentistry during the endodontic treatment to shape the root canal of the tooth while removing the pulp when infected. Notwithstanding the use of NiTi instruments is considered the main novelty in the recent evolution of the root canal shaping strategies, up to now a very limited number of numerical and experimental tests has been performed to study deeply their performances and drawbacks.
The aim of this work is to computationally investigate the improvement in the technique due to shape memory alloy versus stainless steel employment. Moreover the behaviour of rotary endodontic instrument produced using Ni-Ti alloys with different mechanical properties is studied. Attention is paid to understand if an appropriate choice of the material could help in reducing the criticality of the treatment in some clinical conditions.
In particular, an accurate geometrical model of a Ni-Ti ProTaper F1 (manufactured by Dentsply Tulsa Dental, USA) was created. The interaction between the rotating file and differently shaped root canals during the insertion and extraction procedure was studied performing FE analyses. The complex thermo-mechanical behaviour of the Ni-Ti alloy was reproduced using an ad hoc computational subroutine (Auricchio F, Petrini L, 2004, International Journal for Numerical Methods in Engineering 61, 716-737). Strain induced by the treatment on a file made of a “standard” Ni-Ti (average properties was used because the specific material employed by the manufacturers was unknown) were compared with the ones of a “virtual” ProTaper F1 made of stainless steel. Moreover, other two Ni-Ti alloys, a “long” and a “super” alloy, was considered. They present respectively, a wider transformation plateau and an extended hookian behaviour without transformation plateau.
The results accurately shown the advantages of the use of Ni-Ti alloy with respect to stainless steel and the better performance of the “long” alloy in every considered case.
The aim of this work is to computationally investigate the improvement in the technique due to shape memory alloy versus stainless steel employment. Moreover the behaviour of rotary endodontic instrument produced using Ni-Ti alloys with different mechanical properties is studied. Attention is paid to understand if an appropriate choice of the material could help in reducing the criticality of the treatment in some clinical conditions.
In particular, an accurate geometrical model of a Ni-Ti ProTaper F1 (manufactured by Dentsply Tulsa Dental, USA) was created. The interaction between the rotating file and differently shaped root canals during the insertion and extraction procedure was studied performing FE analyses. The complex thermo-mechanical behaviour of the Ni-Ti alloy was reproduced using an ad hoc computational subroutine (Auricchio F, Petrini L, 2004, International Journal for Numerical Methods in Engineering 61, 716-737). Strain induced by the treatment on a file made of a “standard” Ni-Ti (average properties was used because the specific material employed by the manufacturers was unknown) were compared with the ones of a “virtual” ProTaper F1 made of stainless steel. Moreover, other two Ni-Ti alloys, a “long” and a “super” alloy, was considered. They present respectively, a wider transformation plateau and an extended hookian behaviour without transformation plateau.
The results accurately shown the advantages of the use of Ni-Ti alloy with respect to stainless steel and the better performance of the “long” alloy in every considered case.