Page 102 - Demo

Chapter 6100included. Root canal treatments that had been started outside the undergraduate clinic were excluded. The cohort of patients who received calcium hydroxide intracanal medicament during their molar root canal treatment consisted of patients who were treated between September 2010 and September 2011 (n = 334). The time frame for data collection of this sample could not be expanded without introducing risk of bias because from September 2010, the method of root canal preparation had been revised, and from September 2011, using calcium hydroxide as an intracanal medicament during root canal treatment had been removed from the protocol. Because calcium hydroxide was available in the undergraduate clinic for a few more months, the cohort of patients who did not receive an intracanal medicament during their molar root canal treatment consisted of patients who were treated between September 2012 and September 2014 (n = 385). A sample size calculation was performed with the use of G*Power 3.1.9.7 for Windows (Heinrich Heine University, Düsseldorf, Germany). For this, the incidence of interappointment emergencies was estimated from the literature which indicates that it ranges from 1.5% to 5.5% [4] with a tendency towards 1.5% [1,2,27]. Hence, for the sample size calculation, the lower and upper limit of the reported range of interappointment emergencies were used for proportion 1 and 2, respectively. The sample size calculation revealed that 290 patients were required in each group (α type error = 0.05, power = 0.8).The included treatments were performed by dental students in their final years of undergraduate training. They used the then prevailing protocols, that only differed concerning the intracanal medicament use. All treatments were performed under isolation of rubber dam. Before the root canal treatment was initiated, any caries, if present, were excavated. Throughout the preparation process, the root canal system was irrigated with 2% sodium hypochlorite using 10 cc Luer Lock Tip Syringes (Terumo Medical Corporation, Somerset, NY, USA) with irrigation needles (NaviTip®, Ultradent Products. Inc., South Jordan, UT, USA) until 1-2 mm short of working length. The root canals were prepared with rotary instruments (Mtwo®, VDW, Munich, Germany) in a modified crown down sequence: after the coronal part of the canals were enlarged with rotary size 20.06, the whole Mtwo® sequence from size 10.04 to size 40.04 was used to full working length. The working length was always confirmed by means of a periapical radiograph before rotary preparation was conducted to this length. Electronic length measurement devices were available to determine the working Annemarie Baaij.indd 100 28-06-2023 12:26