Evaluation of microcrack formation during root canal preparation using hand, rotary files and self-adjusting file in primary teeth: An in vitro study

Abstract

Background. Pediatric endodontics is a field with constant evolution, resulting in the shifting of paradigms from the use of conventional hand files to rotary files for biomechanical preparation in primary teeth. Biomechanical preparation plays a crucial role in the success of root canal treatment. Primary teeth need special attention since they differ from permanent teeth in root canal morphology. Cleaning and shaping of the canals damage the root dentin, leading to dentinal cracks. Newer techniques for root canal preparation, including Ni-Ti rotary files and SAF system, have been developed for use in pediatric endodontics to overcome the drawbacks of conventional methods. The present study compared dentinal defects formed by rotary systems in primary teeth. Methods. Eighty primary teeth were included. The teeth were decoronated with a diamond disc. All the roots were inspected for any pre-existing cracks or craze lines under transmitted light under a stereomicroscope. The specimens were then divided into four groups (n=20): group 1: control, group 2: hand files (HF), group 3: ProTaper files, and group IV: SAF files. The samples were instrumented according to the group they were assigned to. Results. The HF and SAF groups exhibited fewer microcracks. Dentinal microcracks were observed in roots prepared with rotary ProTaper files. There were significant differences between HF/SAF and rotary files (P<0.05). Conclusion. Stainless steel hand K-files and SAF instruments resulted in fewer dentinal damage than the ProTaper Universal files. SAF exhibited satisfactory results with minimal or no crack formation.

Comparative Evaluation of the Incidence of Dentin Microcracks Following Biomechanical Preparation Using Four Different Nickel-Titanium Rotary File Systems: An In Vitro Study

“…Excessive removal of the radicular dentin, especially in "danger zones," may result in strip perforation and vertical root fractures. In addition, the gradual dentinal sclerosis caused by the age-related change in the microstructure of dentin may be correlated with decreased resistance to damage initiation and propagation [ 3 , 10 ]. As the thickness of the dentinal wall directly relates to the tooth's resistance to lateral stresses, excessive canal preparation compromises dentinal thickness and weakens the tooth.…”

“…In endodontic therapy, the prognosis is positively connected with the most effective cleaning and shaping techniques [ 1 ]. Nickel-titanium (NiTi) rotary instruments have significantly improved root canal preparation since they have made instrumentation easier and faster [ 2 , 3 ]. Human dentin is viscoelastic, and during biomechanical preparation, instruments contact the root canal wall and apply forces that lead to a temporary stress concentration on the dentin.…”

Assessment of the Shape and Diameter of the Root Canal and the Risk of Perforation After Using Rotary System Versus Manual Instruments in Extracted Second Primary Molars: An in -Vitro Study

“…Results showed that molars prepared by H-files had higher fracture root resistance (mean ±SD 729.38±110.07) than molars prepared by Fanta AF baby files (±SD 668.19±120.62), but without significant difference (P=0.189). This could be explained by the fact that rotary files cause more microcracks or craze lines on the dentinal walls during preparation (Panda et al, 2021).…”

“…Microcracks or craze lines sometimes appear on the walls because of the rotational force used to prepare root canals with rotary files. The instruments' flute shape, crosssectional geometry, tip design, progressive or continuous taper, constant or variable pitch, and other factors all contribute to the severity of these defects (Panda et al, 2021).…”