RESUMEN
The aim of this study was to determine the remaining dentin thickness (RDT) in the apical 4 mm following four cleaning and shaping techniques. Sixty human adult extracted mandibular incisors and 60 mesial buccal canals of mandibular molars were assigned to five groups of 12 teeth for each tooth type: Step-down stainless steel hand instrumentation, Lightspeed, Profile GT and 0.4 taper, K3 "g pack," control group. After instrumentation the teeth were sectioned at 0.5, 1.5, 2.5, and 3.5 mm short of working length (WL) and evaluated for the minimum RDT at each level. ANOVA of RDT showed significant differences among levels and techniques. For incisors, no technique yielded greater RDT than the other techniques (p < 0.0001). For molars, K3 had greater RDT than the other techniques (p = 0.0006) at the 1.5, 2.5, and 3.5 mm levels. While there were significant statistical differences in RDT among techniques at different levels, further study would be required to determine any significant clinical difference in RDT.