Postoperative pain following endodontic irrigation using 1.3% versus 5.25% sodium hypochlorite in mandibular molars with necrotic pulps: a randomized double-blind clinical trial.

AIM: This randomized, prospective, double-blind, clinical trial assessed the effect of 1.3% and 5.25% sodium hypochlorite (NaOCl) as irrigants on post-endodontic pain and medication intake following root canal treatment of mandibular molars with nonvital pulps. METHODOLOGY: Three hundred and eight patients, each with one symptomatic or asymptomatic molar, were randomly assigned, using the permuted-block method, into two equal groups according to NaOCl concentration: 1.3% or 5.25% (n = 154). For both groups, syringe irrigation was performed using a 27-gauge needle advanced into the canal to a depth of 3 mm from the working length; 3 mL were used between every two consecutive instruments. All root canal treatments were carried out in two visits, with no intracanal medication, by trained postgraduate students. The canals were prepared using the ProTaper Universal rotary system during the first visit. In the second visit 7 days later, the same irrigant per group was used and the canal walls were reprepared with the final instrument before filling the canal using the modified single-cone technique with an epoxy resin-based sealer. Patients assessed their postoperative pain using a 0-10 numerical rating scale immediately after instrumentation, 3, 24, 48 h and 7 days after the first visit and immediately following root canal filling. The incidence of rescue medication intake (Sham or analgesic) was also recorded; patients received a sham capsule to be used first, but, if pain persisted, an analgesic was prescribed. Outcome data were analysed using Mann-Whitney U-test, Friedman's test, Wilcoxon's rank test and chi-square (χ2 ) test. Relative risk reduction (RRR) and its 95% confidence interval (CI) were calculated for binary data. RESULTS: The incidence and intensity of postoperative pain were significantly lower with 1.3% NaOCl than 5.25% NaOCl at all time-points (P < 0.05). Postoperative pain intensity exceeded preoperative pain at 3 and 24 h with 5.25% NaOCl only (P < 0.05). The RRR in pain incidence was 38% (95% CI: 17%, 54%) immediately after instrumentation, 41% (95% CI: 31%, 49%) at 3 h, 42% (95% CI: 32%, 51%) at 24 h, 59% (95% CI: 45%, 69%) at 48 h, 62% (95% CI: 27%, 80%) at 7 days and 81% (95% CI: 68%, 89%) after root filling. RRR was 38% (95% CI: 1%, 61%) for sham intake and 69% (95% CI: 37%, 85%) for analgesic intake. CONCLUSIONS: Using 1.3% NaOCl was associated with less intense and less frequent post-endodontic pain than 5.25% NaOCl in mandibular molars with nonvital pulps treated in two visits. The incidence of pain was reduced by up to 60% within the week post-instrumentation and 80% after root canal filling and the rescue analgesic intake by about 70% on using 1.3% NaOCl compared to 5.25% NaOCl.

In vitro culture of erythroid colonies from human fetal liver and umbilical cord blood.

Colony formation by erythroid precursors from human fetal liver, umbilical cord blood and adult peripheral blood has been studied in a plasma clot culture system. Fetal liver (FL) was obtained at post-mortem examination from 13-22 week abortuses. After mincing in Hanks' solution, cells in suspension were harvested by Ficoll-Hypaque centrifugation. Mononuclear cells were obtained by centrifugation of umbilical cord blood (CB) and normal adult peripheral blood (PB). All three types of preparations were incubated up to 14 d in 0.1 ml plasma clot cultures containing 0-4 u/ml erythropoietin (Epo) and 10(6) cells/ml. No colonies formed in the absence of Epo. Normal adult PB produced late-appearing colonies; there were no colonies at day 7 and up to 100 colonies/0.1 ml at day 14. CB produced early and late colonies with up to 200 colonies/0.1 ml at day 7 and 125 at day 14. Cells from FL produced many early colonies; over 1500 colonies/0.1 ml were sent at day 7 and there was a subsequent decline in colony count with longer incubation. In cultures of both CB and FL, colonies composed of either mature or immature cells were noted during both early and late stages of incubation suggesting that these cell sources contain a heterogeneous population of erythroid colony progenitors. Measurement of differential beta and gamma globin chain synthesis by erythroid colonies grown from fetal liver and umbilical cord blood gave results similar to those obtained by direct pulse-labelling of the original source of the cultured cells.