LAUSR

AIM To assess postoperative pain and bacterial reduction following the use of XP-endo Shaper versus conventional rotary files in preparation of oval canals with necrotic pulps. METHODOLOGY This superiority, parallel, randomized, double blinded clinical trial was conducted in the clinic of the Endodontic Department, Faculty of Dentistry, Cairo University, Egypt. Sixty single- canalled mandibular premolars with necrotic pulps were randomly assigned into two equal groups. Canals were instrumented using XP-endo Shaper files in the intervention group and iRaCe rotary files in the control group. Bacterial samples were taken before and after canal instrumentation. Incidence and severity of postoperative pain was assessed using a modified VAS after 6, 12, 24 hours and daily for 5 days. A culture method was used to assess the number of bacterial colony forming units. Incidence of analgesics intake as well as flare-ups was recorded. Data were analyzed using Chi-square, Fisher Exact, Mann-Whitney, Independent t-test, and Spearman's correlation for pain and bacterial counts. RESULTS The XP-endo Shaper compared to the iRaCe group was associated with a significantly lower incidence of postoperative pain at 6, 12, and 24 hours (P=0.039, 0.047, and 0.026 respectively), and severity of postoperative pain at 6 hours (mean difference: 1.33, 95% CI: 0.307-2.352, P=0.02), 12 hours (mean difference: 1.1, 95% CI: 0.26-1.936, P=0.007), 24 hours (mean difference: 0.94, 95% CI: 0.178-1.701, P=0.008), and 48 hours (mean difference: 0.97, 95% CI: 0.192-1.747, P=0.038). There was a significant decrease in bacterial count following canals instrumentation in both groups (p<0.001) with no significant difference between them (mean difference: 0.83x105 , 95% CI: 0.336x105 -1.996x105 , P=0.56). A weak correlation existed between postoperative pain severity and bacterial counts (P=0.54). There was no significant difference in analgesics intake between the two groups (P=0.085). Flare-ups occurred in 3.3% of teeth in the iRaCe group, while no flare-ups occurred in the XP-endo Shaper group. CONCLUSIONS XP-endo Shaper was associated with a significantly lower frequency of postoperative pain for up to 24 hours, and lower severity of postoperative pain for up to 48 hours compared to iRaCe files. Both systems were equally effective in bacterial reduction from oval root canals with necrotic pulps.