The Effect of Different Rotary Systems on Creating Intracanal Dentinal Defects: An Ex Vivo Study

The creation of intracanal dentinal defects during root canal preparation is a concern in endodontic treatment; as such defects can compromise the integrity of the tooth and potentially lead to fractures or failure of the treatment. Rotary systems, commonly used for shaping root canals, vary in their design, material, and cutting mechanisms, which may influence the extent of dentinal defects they induce. However, the comparative impact of different rotary systems on the formation of these defects remains unclear.

The aim of this ex vivo study was to compare the effects of four rotary systems (One-curve, One-shape, Neolix, and ProTaper Universal) on the creation of intracanal dentinal defects in extracted human teeth.

In this ex vivo study, seventy extracted human mandibular incisor teeth with straight roots and no extra canals or existing dentinal defects were selected and randomly divided into five groups, including one control group and four experimental groups. In the control group (n=10), no instrumentation was performed. In the experimental groups (n=15 each), instrumentation was done using the rotary systems ProTaper Universal, Neolix, One-shape, and One-curve, respectively. All groups received the same amount of irrigation: 12mL of 2% sodium hypochlorite followed by 3mL of sterile saline. The roots were then horizontally sectioned at 3, 6, and 9 mm from the apex and evaluated under a stereomicroscope for the presence of intracanal defects. Data were analyzed using Chi-square test.

The lowest and highest rates of dentinal cracks were observed in the One-curve and One-shape groups, respectively. No significant differences were observed among the experimental groups (p Value=0.46).

All tested rotary systems induced dentinal defects. The lowest and highest incidence of dentinal defects occurred in teeth prepared using the One-curve (26%) and One-shape (53%) rotary instruments, respectively.