# In Vitro Evaluation of Root Surface Temperature Using Different Endodontic Filling Techniques
## 2 Materials and Methods
Before recording, the canal was dried as in the in-vivo procedure using ethanol 90%, 0.5 mL/canal, and paper points until it was visually completely dry. Subsequently, the canal was coated with sealer. The sealer used in this study was AH Plus (Dentsply Sirona Inc., Charlotte, NC, USA). The fluid to simulate the periodontal blood flow was heated up using heating plates (VWR advanced; VWR international, Radnor, PA, USA) according to [PERSON] et al. [21] (Figure 1). The experiment was started as soon as the temperature of the tooth was stable within the range of 36.0-37.0 \({}^{\circ}\)C. The temperature was checked using the IRBIS 3.1 plus software program (InfraTec GmbH Infrarotsensorik und Messtechnik, Dresden, Germany) and the thermal imaging camera (VarioCAM HD; InfraTec GmbH Infrarotsensorik und Messtechnik, Dresden, Germany) to guarantee intra-experimental comparability. At a flow rate of 0 mL/min, the tooth was first heated to 37.0 \({}^{\circ}\)C, and once that temperature was reached, the pump was turned off, and recording started. The sample thus started cooling down passively to room temperature after deactivation of the pump. The camera's running time was 80 s. Obturation was started after 10 s and stopped 10 s before the time expired. Four different warm obturation methods, with \(n\) = 5 in each group, were investigated in this study in relation to heat development in the apical tissue, and the cold single-cone technique was used in the control group. The following obturation methods were investigated:  
1. Single-cone technique (control group);
2. Gutta-percha-coated rigid carrier technique (GuttaFusion);
3. Squirting technique (injection technique);
4. Continuous wave technique;
5. Schilder technique. The single-cone technique (I) was carried out by inserting a previously adapted master point (ISO standardized gutta-percha, 28 mm, taper 2%; VDW GmbH, Munich, Germany) ISO 40 into the canal after the canal walls had been coated with sealer. The master point was then shortened coronally using a heated instrument and compacted vertically using a size 3 plugger. During obturation with the GuttaFusion technique (II), the heating device was set to heat setting 1 for all sizes of GuttaFusion(r) obtutators (ISO 40, VDW GmbH, Munich, Germany; GuttaFusion oven, VDW GmbH, Munich, Germany). A mean temperature of about 160 \({}^{\circ}\)C was measured using a thermocouple (dual-display digital Multimeter, M-3850D; Roline-SECOMP Electronic Components GmbH, Ettlingen, Germany), in compliance with the manufacturer's specifications. A sealer was applied to the root canal, and after the heating time ended, the GuttaFusion obtutator was inserted into the root canal and coronally abbreviated. For the squirting (injection technique) (III), continuous wave (IV), and Schilder (V) techniques, the BeeFill 2 in1 unit with a BeeFill gutta-percha cartridge (23 G = 0.6 mm; VDW GmbH, Munich, Germany) was used and set at 200 \({}^{\circ}\)C for the heat plugger and 180 \({}^{\circ}\)C for the backfill equipment. The squirting technique (III) was performed by inserting the backfill equipment 1 mm short of the root apex and applying heated gutta-percha in helical motions until the entire canal was filled. Subsequently, vertical compaction was carried out. For the continuous wave technique (IV), a size 2 heat plugger was adapted to a working length of 5 mm. After sealer application, the chosen master point was inserted into the canal. Using the heated plugger, the master point was trimmed 5 mm short of the root apex and vertically condensed with a cold plugger of the same size. Backfilling involved the application of heated gutta-percha in 1-2-mm pieces using the BeeFill 2 in1 unit (VDW GmbH, Munich, Germany), followed by vertical condensation with a cold plugger after each section. In preparation for the Schilder technique (V), two heat pluggers were customized at different working lengths. The first plugger was set 7 mm short of the root apex, while the second was set 5 mm short.