This is an original in vitro research conducted in Department of Conservative Dentistry and Endodontics, Ghaziabad in November, 2014. In this study 30 periodontally compromised freshly extracted human single-rooted premolars, verified radiographically were selected. Teeth with curved roots, fractures, cracks or any other defects were excluded from the study. The consent from patients and ethical board was obtained for procuring the extracted teeth. They were stored in a 0.1% thymol. Access cavity preparation was done and working length was determined by inserting a size 10 K file (Dentsply Maillefer) into the root canal until it was visible at the apical foramen and subtracting 1mm from that length. Biomechanical preparation of the root canal using a single use instrument i.e. Reciproc R25 was done. A VDW Silver electric motor was used to activate the instrument in a reciprocating motion. Gently an in-and-out pecking motion was used to reach the apex with amplitude of approximately 3 mm. A brushing action was combined with a gentle apical pressure against the lateral walls. Irrigation is done by 25 mL of 2.5% NaOCl followed by 5 mL of 17% EDTA aqueous solution. Five mL of a 2.5% NaOCl solution was used for final irrigation. The canals were dried with paper points after irrigation. The same operator did all intracanal procedures to eliminate interoperator variability. Teeth were randomly divided into three experimental groups according to the obturation technique [10].

The Calamus Flow handpiece was used with a one-piece gutta percha cartridge and integrated cannula to dispense warm gutta-percha. The cartridges was used on a single patient [11]. The Calamus dual 3D obturation system (Dentsply Maillefer, Ballaigues, Switzerland) was used along with AH Plus root canal sealer (Dentsply De Trey, Konstanz, Germany).

A size #25 verifier was checked for its fitting in the canal at the working length. The same size obturator was selected and heated in the ThermaPrep Plus Oven (Dentsply Maillefer, Holland). The canal was dried followed by application of AH Plus sealer to the coronal portion of the canal. Then the obturator was slowly placed in a single motion at the working length. The obturator was severed at canal orifice after cooling the gutta percha [3].

Cold lateral compaction was done by a master gutta-percha cone of size 25 and accessory gutta-percha points of size 20 and 15 with AH Plus sealer. The excess coronal gutta-percha was removed by a heated instrument [12].

The above mentioned three experimental groups were compared with control group which consists of two teeth without obturation. The canal access of all the teeth was restored with Cavit-G (3M Espe, Germany), and the teeth were stored under 100% humidity at 37°C. Teeth were radiographed in buccolingual and mesiodistal direction to confirm the adequacy of root fillings. Assessment of quality of obturation was done by calculating the filling area and voids in each tooth at coronal, middle and apical third of the root canal by CS9300 CBCT scanner (Carestream Healthcare India (P) Ltd, India) in the high resolution dental mode (i.e. 90 micron resolution) using the On Demand 3D App software.

The amount of filling area in the obturation in all the three groups is shown in [Table/Fig-1]. The CBCT images of the obturated tooth are shown in coronal, sagittal, axial and 3D view [Table/Fig-2]. Voids were observed in all obturated samples regardless of the groups examined. The data was statistically analysed by One-Way ANOVA test followed by multiple comparisons by Tukey HSD. A p-value of 0.05 was considered to be statistically significant. These results demonstrated that group I (Obturation by Calamus) resulted in maximum filling area followed by group II (Thermafill) and group III (Lateral compaction). Maximum amount of obturating material was seen with obturation by Calamus technique which was also statistically significant. Maximum amount of gutta-percha was found at coronal third and least in apical third of the root canal in all the groups [Table/Fig-1,2]. There were no voids with Calamus at three level cervical middle and apical, with Thermafill voids are seen at cervical region only but with lateral condensation voids are seen at all the three levels cervical and middle region.

[Table/Fig-2]:

CBCT images of the obturated tooth (a) Coronal (b) Sagittal (c) Axial (d) 3D images

Improper obturation of root canal leads to post-operative complications resulting in failure of endodontic therapy. The root canal space is sealed perfectly by a three-dimensional obturation of the root canal system [11]. It prevents penetration of bacteria and their products into the periradicular tissues and create a favourable biological environment for the healing of peri-apical tissues.

The disposable instruments have been recommended to decrease instrument fatigue and cross contamination. It also reduces the cost and the number of NiTi rotary instruments required for root canal preparation. Reciproc instrument (VDW, Munich, Germany) is made of standard NiTi alloy with M-wire treatment [10,12]. Three sizes R25, R40 and R50 are used according to the initial canal diameter. The taper of the instrument is 0.08, 0.06 and 0.05 mm for the R25, R40 and R50 instruments, respectively. A reciprocating movement of 10 cycles per second is used. The instrument is rotated at 360 degrees at three reciprocating cycles [13]. There is no dental literature regarding the quality of obturation after using Reciproc rotary file for biomechanical preparation.

Different type of obturating systems can influence the quality of obturation [14]. In this study lateral compaction, Thermafil and Calamus were used for obturation to ensure which technique have the maximum voids and filling area after obturation. The quality of obturation after using Calamus obturating system has not been assessed yet. The Calamus dual 3D (Dentsply Maillefer, Ballaigues, Switzerland) Obturation System is one unit that conveniently combines both Calamus “Pack” and Calamus “Flow” handpiece. With the Pack and Flow positioned side-by-side, a dense apical plug is created. Then Flow will be used to deliver the gutta-percha. An ergonomically designed hand piece has a 360 degree activation cuff which provides a smooth, continuous expression of gutta-percha [6].

The Calamus Pack handpiece with an Electric heat plugger (EHP) is utilized to thermosoften, remove and condense guttapercha in the downpacking phase of obturation. The EHPs are available in three ISO colour black, yellow, and blue which correspond to working end diameters and tapers of 40/03, 50/05, and 60/06, respectively. The cone beam computed tomography was used to outweigh the limitation of the methodologies previously applied in endodontic treatment studies, such as displacement of the filling debris during cleavage and two-dimensional imaging on a three-dimensional structure in a non-invasive manner [15,16].

The 3D obturation was best with Calamus as compared to Thermafill and lateral condensation. Best results with Calamus could be explained on the basis of the maximum inert core material, minimum amount of sealer and a higher degree of homogeneity associated with the calamus [6]. Poor results with Thermafill as compared to calamus can be explained by the fact that as in Thermafill obturation, guttapercha can flow through the apical foramen. Thermafill obturation has some other disadvantages like the carrier in the guttapercha may get stripped off in curved and elliptical canals. Worst results were shown by lateral compaction which lack homogeneity of gutta percha mass, less adaptation to canal walls, irregularities and increased number of voids. This is supported by previous studies [10]. Thermafil technique was superior to lateral condensation. It is less time consuming, resulted in filling of accessory canals with gutta percha, more homogeneous mass, had fewer voids and replicated the surface of the roots better.

Maximum amount of voids were also seen in lateral compaction followed by Thermafill and Calamus. More voids were seen in coronal as compared to middle and apical third. This can be due to more amount of guttapercha in coronal third of the root canal. The quality of root canal obturation in thirds of the root length was also assessed using micro-CT. The lowest mean volume of voids was found in the coronal and middle third. None of the tested materials led to a void free canal filling [15].

Within the limitations of this study, it can be concluded that none of the obturation technique is able to seal the root canal completely. The Calamus may be a good alternative for perfect quality of 3D Obturation and it may be helpful in obtaining the good hermatic seal in endodontically treated teeth in future. Further research is required in determining the amount of filling area and voids in other obturation techniques.