A Study On Application Of Continuous-wave Condensation Technique With Thermoplasticized Gutta-percha

Root canal therapy (RCT) is an essential method for treating various endodontic and periapical diseases. Obturation of the cleaned and shaped root system is vital in endodontic therapy to prevent the imgress of bacteria into the cleaned and disinfected root canal space, in addition to preventing the recolonization of bacteria present at the time of root filling. Providing a filling in the root canal capable of sealing the coronal, apical, and lateral openings is one of the main treatment objectives.With the advent of the thermoplasticized gutta-percha obturation techniques, a lot of new devices have been introduced to achieve a three-dimensional obturation of the canal system. One of these techniques is continuous-wave condensation technique with thermoplasticized gutta-percha that was developed by Buchanan(1994). Further development of the original technique led to the production of E&Q Plus system.E&Q plus system is a root canal filling set, including two techniques. Their working principles are continuous-wave technique and injectable technique. It support faster, safer obturation and provide a better temperature control and duration of heat during application except some limitations.The purpose of this study was to evaluate the quality of continuous wave condensation technique and lateral condensation technique in vivo and in vitro. [Objective] To evaluate the apical sealability of different combinations of root canal preparation and continuous-wave condensation technique in vitro.[Materials and Methods] Twenty-four extracted maxillary premolars with two canals were randomly divided into four equal groups of ten canals, instrumented and obturated according to different techniques. Apical microleakage was determined using dye penetration and clearing technique, and measured under the stereomicroscope.[Results] No statistical differences were found among any combinations of the instrumentation and obturation technique in terms of apical microleakage (P＞0.05).[Conclusion] Apical sealing ability between continuous-wave technique and cold lateral compaction was showing no significance differences; Apical sealing ability was not influenced by preparation technique for straight or slight-waved canals.Experiment two: Endodontic microleakage test by a new quantitative method with glucose[Objective] To assess the sealing ability of continuous-wave condensation technique by a new quantitative method using glucose.[Materials and Methods] Thirty extracted mandibular premolars with one single canal were randomly divided into two experimental groups of ten canals and two control groups with five in each, The experimental groups were prepared using crown-down technique and obturated respectively by lateral condensation of cold gutta-percha or continuous-wave condensation. With the leakage test device, coronal 1 mol/L glucose solution was forced under a hydrostatic pressure of 1.5 kPa toward the apical part of the root. Leakage was measured by the concentration of leaked glucose in apical reservoir at 1, 4, 7, 20 days with the enzymatic glucose oxidase method.[Results] No significant difference of sealing ability was found among two test groups at 1 and 20 days. The difference of leakage between two test groups was significant at 4, 7days. Cold lateral condensation showed the higher leakage than continuous-wave condensation.[Conclusion] Teeth that were obturated using lateral condensation of gutta-percha leaked faster than teeth that were obturated using gutta-percha with the continuous-wave condensation technique. There was no statistical difference between cold lateral compaction and continuous-wave condensation in the numbers of teeth that demonstrated leakage.Experiment three: Analysis of the percentage of gutta-percha filled area (PGP) in apical cross sections[Objective] To compare the apical density of continuous-wave condensation technique and cold lateral compaction in straight canals. [Materials and Methods] A total of twenty freshly extracted human mandibulary premolars with one single canal were divided into two identical groups on the basis of root canal length and apical diameter. The root canals were prepared with a rotary system in a crown-down technique and obturated with either cold lateral compaction or continuous-wave condensation with E&Q plus system. All roots were horizontally sectioned at 2mm, 4mm, 6mm, 8mm from the apical foramen using low-speed saw. The cross-sectional area of the canal and gutta-percha were all measured using an image-analysis programme. The PGP was then calculated.[Results] With regard to PGP, no significant difference was found at 2mm, 4mm, 6ram from apex between cold GP group and warm GP group, but warm GP group were statistically higher than cold GP group at 8mm from apical foramen. [Conclusion] Although continuous-wave condensation technique and lateral compaction technique had no significant difference in the filling of the apical portion of canal, continuous-wave condensation technique was superior to lateral compaction technique in the filling of middle and coronal portions of canals.PartⅡClinical application of continuous-wave condensation technique[Objective] To assess the obturation quality and the short term of clinical curative effect of continuous-wave condensation technique.[Materials and Methods] 32 patients with pulpitis or periodontitis were admitted for continuous-wave obturation. Then the obturation quality and the short stage of clinical curative effect of continuous-wave condensation were assessed by radiography and clinical observation after 1 week, 3 months.[Results] There was no posttreatment pain or failure occurred after 1 week and 3 months.[Conclusion] E&Q plus system is a faster, safer root canal filling set. The short-term clinical curative effect of continuous-wave condensation was quite well.