StomatologyEduJournal1-2015 | Page 66

GERODONTOLOGY (29-36), monitoring different systems’ behavior and mentioning varying results. The incidence ranges from 1.3% - 10% (36) with a mean prevalence of 1.6% (37). Retrospective clinical studies have shown that the separation incidence for rotary NiTi instruments is 7 to 8 times greater than that of hand instruments (38, 39). The use of rotary instruments can be significantly improved with the combined use of lubricant agents inside the root canal. These agents facilitate the movement of the instrument inside the narrow environment of the root canal, by decreasing cyclic fatigue and torque load of rotary instruments, especially when they have extra chelating action (40). This way the clinician can handle the rotary instruments more easily and decrease the chance of iatrogenic events and particularly instrument separation. The application of sodium hypochlorite and aqueous chelating solutions (i.e. EDTA) compared to agents in paste form (PC-Prep) has been shown to cause less instruments’ fractures (41). 2.2. Dentine microcracks The use of rotary systems for root canal preparation has been related to the creation of deformations and mostly microcracks in the inner walls of dentine due to tensions’ accumulation, especially in the apical third (4244). Similar deformations were not observed after preparation with hand files. Dentine loses its elasticity with age. Consequently, it is possible that these microcracks appear to greater extend in elderly teeth, which may affect their prognosis and increase the possibility of a root fracture. However, this hypothesis has not yet been confirmed. Discussion The investigation of the existing literature has shown that more research is necessary on the application of rotary systems in older people and more emphasis should be placed on Geriatric Endodontics. Conclusions Rotary systems