Effect of Apical Third Enlargement to Different Preparation Sizes and Tapers on Postoperative Pain and Intra-canal Bacterial Reduction: A Randomized Clinical Trial.

BACKGROUND

Apical preparation size plays a vital role in root canal instrumentation, yet the ideal size and taper remain a subject of debate. This randomized clinical trial was designed to assess the influence of different apical preparation sizes and tapers on postoperative pain and intracanal bacterial reduction.

MATERIALS AND

METHODS

Fifty-six patients, diagnosed with necrotic mandibular premolars, were randomized into two groups according to apical enlargement size (#35 or #45). Each group was further divided by taper (0.04 or 0.06), resulting in four groups. Microbiological samples were collected before and after instrumentation, while postoperative pain was assessed at 6, 12, 24, 48, and 72 hours using the Numeric Rating Scale (NRS). Data analysis involved Kolmogorov-Smirnov and Shapiro-Wilk tests for normality, with Kruskal-Wallis, Friedman, and Fisher's exact tests; statistical significance was set as p < 0.05.

RESULTS

At 6 and 12 hours, pain scores differed significantly between groups (p < 0.05), with the highest levels at 6 hours followed by a significant decline by 12 hours (p < 0.05). All treatment groups showed a marked reduction in bacterial counts after instrumentation (p < 0.001). The percentage reduction varied significantly among groups (p < 0.001).

CONCLUSIONS

Larger apical preparations may induce early postoperative pain, yet improve intracanal bacterial reduction. Increased taper also contributes to enhanced bacterial reduction.