Introduction: Minimally invasive endodontics (MIE) is the latest innovation in endodontics that focuses on minimal mechanical preparation; it has a great impact on preserving the fracture strength of teeth.
Aim of the study: To compare the fracture resistance of mandibular molar roots following instrumentation using TruNatomy versus ProTaper Next rotary files.
Materials and methods: This study was conducted on thirty permanent mandibular molars. Teeth were randomly divided into two equal groups. Decoronation of the crown was done and the distal root was sectioned from the mesial root and acted as control. Study Group I: Fifteen mesial roots (MB and ML canals) were prepared using TruNatomy (TRN) rotary files up to the prime file (26/.04). Study Group II: Fifteen mesial roots were prepared using ProTaper Next (PTN) rotary files up to size X3(30/.07). Control Group: The distal root of each tooth. Roots were embedded in acrylic resin blocks and subjected to fracture testing. Data were statistically analyzed.
Results: Roots prepared with TRN were significantly more fracture resistant than roots prepared with PTN. In addition, a significant difference was noted between the mesial and distal roots within each group.
Conclusions: Mandibular molar mesial roots prepared with TRN rotary files (26/.04) are significantly more fracture resistant than those prepared with PTN rotary files (30/.07). In addition, intact mandibular molar distal roots were significantly less prone to fracture than the mesial roots prepared with both systems.