Influence of kinematic motion and instrumentation strategy on apical debris extrusion during root canal preparation: An in vitro study.

BACKGROUND

Endodontic treatment aims to eliminate infection while maintaining the health of the tooth and surrounding tissues. Apical extrusion of debris during instrumentation is unavoidable and may lead to inflammation, postoperative pain, or delayed healing. The extent and direction of extrusion are influenced by the instrumentation system and motion pattern.

AIMS: This study aimed to evaluate the effect of kinematic motion (continuous rotary vs. reciprocating) on apical debris extrusion during mechanical root canal preparation.

MATERIALS AND

METHODS

Thirty freshly extracted human single-rooted teeth with fully formed apices were standardized in length and mounted in preweighed Eppendorf tubes to collect extruded debris. The samples were randomly assigned into two groups (n = 15 each) and instrumented using either ProTaper Gold (PTG; continuous rotation) or ZenFlex ONE (reciprocating files) according to manufacturer instructions. A single operator performed all instrumentation. Irrigation was carried out using 2.5% sodium hypochlorite. The volume of irrigant was kept consistent for all samples to ensure standardization. After instrumentation, the extruded debris was incubated until complete drying. The debris was then weighed using a high-precision microbalance.

STATISTICAL ANALYSIS USED: Mann-Whitney U test was used for statistical analysis; the significance level was set at P < 0.05.

RESULTS

PTG produced significantly more apically extruded debris (1.49 ± 0.69 g) than ZenFlex ONE (0.85 ± 0.47 g), with P = 0.009.

CONCLUSIONS

This study demonstrates that the ZenFlex ONE reciprocating system significantly reduces apical debris extrusion compared to the PTG rotary system. The reciprocating motion appears to favor coronal evacuation of debris, thereby limiting its apical displacement. This may reduce postoperative pain and inflammatory complications, particularly in teeth with necrotic pulps or periapical lesions.