| 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 ingression 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-Pereha 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 supports 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. The main contents and results of the study are presented as follows:1 The microleakage study on continuous-wave condensation technique with thermoplasticized gutta-percha applied in root canal fillingForty four entire extracted human single-rooted teeth were selected, root canals were instrumented using the ProTaper Nickel-Titanium hand-files. The samples were randomly divided into A, B groups. Group A was obturated with E&Q plus system, Group B was obturated with the cold lateral condensation of gutta-percha. Dyeing lines were measured to reflect the micro-leakage of different obturated materials. Micro-chink between root canal and the fillings was measured under SEM. The results showed apical micro-leakage lines of group A had mean length of (1.26±0.44)mm; micro-chink of group A had mean length of (2.87±1.07)μm. Apical micro-leakage lines of group B had mean length of (2.35±0.67) mm; micro-chink of group B had mean length of (5.80±0.74)μm. Microleakage and micro chink were significantly different between E&Qplus system and cold lateral condensation of gutta-percha(P< 0.01). These results suggested that under in vitro condition, the continuous-wave condensation with thermoplasticized gutta-percha adapts better to the canal wall, showing better root canal sealing ability.2 The microleakage study on continuous-wave condensation technique with thermoplasticized gutta-percha applied in root canal filling prepared with different methods.Forty four entire extracted human single-rooted teeth were selected, root canals were instrumented using the ProTaper Nickel-Titanium hand-files. The samples were randomly divided into four groups which each contained 10 teeth. During root canal preparation every canal in group A was rinsed with 3% hydrogen peroxide solution and saline alternatively, every canal in group B was rinsed with 3% hydrogen peroxide solution and saline alternatively and assisted with ultrasound technique, every canal in group C was rinsed with EDTA solution and sodium hypochlorite solution with prepared and assisted with ultrasound technique, every canal in group D was rinsed with EDTA solution and sodium hypochlorite solution and assisted with ultrasound technique. The specimens in Group A ,B,C were filled with AH-plus sealer; The ones in Group D were filled with RoekoSealsealer. All canals were obturated with E&Q plus system. The results showed apical micro-leakage lines of group A had mean length of (1.33±0.46)mm, apical micro-leakage lines of group B had mean length of (1.44±0.40)mm, apical micro-leakage lines of group C had mean length of (1.34±0.42)mm, apical micro-leakage lines of group D had mean length of (0.99±0.19)mm. No significant difference was found between group A and group B (P>0.05). No significant difference was found between group B and group C (P>0.05). Microleakage was significantly different between group C and group D (P<0.05). These results suggested that that root canal preparation had not significant effect on microleakage of thermoplasticized gutta-pereha obturation, but the type of sealer had more influence on it. RoekoSeal adapts better to root canal than AH-plus sealer, showing better root canal sealing ability with continuous-wave condensation technique. 3 Short-term curative effect of filling with continuous-wave condensation technique with thermoplasticized gutta-perchaIn order to observe the short-term curative effect of heated gutta-percha of the E&Q plus system, Fifty teeth were divided into 2 groups. Group A contained 24 teeth, group B contained 26 teeth. All the teeth were instrumented using the ProTaper Nickel-Titanium hand-files. Group A was obturated with E&Q plus system, Group B was obturated with the cold lateral condensation of gutta-percha. The patients were examined respectively after 1 week,1 months and 3 months. Then the success rates were treated statistically. Results: After 1 months and 3months of therapy, the success rates of Group A were 95.83%, 95.65% respectively, while those in Group B were 92.30%, 92.30%. There was no statistical difference between the two groups (P>0.05). But absolute value of the achievement ratio of the continuous-wave condensation group is higher than cold lateral condensation of gutta-percha group. Continuous-wave condensation technique, to a certain extent, can improve the short-term curative effect of root canal filling, It is an ideal root canal filling technique. The long-term clinical efficacy of the technology needs further observation.
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