The as a carrier for obturating primary

The best obturation technique is the one that provides optimal filling (apical seal) with least number of voids5. In present study for standardization, a common biomechanical procedure followed by obturating with ZOE obturating material of same radioopacity and consisitency were selected as it is easily available and widely used one and have a moderate to high success rate4,5,6. It is a slowly resorbable obturating material and on extrusion it may cause a foreign body reaction, alteration in path of eruption and irritation of the periapical tissue17. In present study the 3 obturation methods were selected based on cost effectiveness, ease of availability and manipulation of materials (Obturation). Lentulospiral is one of the most effective, economical and widely accepted obturation technique1,7,9,18. Design and flexibility of lentulospiral makes it superior in carrying the paste and endodontic sealers in both narrow and curved canals of primary and permanent tooth root7,9,10,18,19. But it’s use is limited due to difficulty in fitting the rubber stopper, instrument fracture and a tendency for extrusion beyond the apex19. During obturation lentulospiral were kept 1mm short of working length which gives less chance for getting engaged in the narrow root canals. This provides enough space for lentulospiral to rotate freely and reduces the risk of fracture1. Insulin syringe is cost effective and is easy to use as a carrier for obturating primary teeth8.  It has a small and slender hub that provide an easy access to the pulpal orifice. Endodontic plugger are most commonly used, simple and effective for incremental packing of thick consisitency filling materials into the canal18. It shows high success rate in long and straight canals such as those of primary anterior teeth19. Due to the limited flexibility of endodontic plugger, it is difficult to obturate a narrow and curved canal till apical portion10.More number of underfilling was shown by insulin syringe (36.4%) group and overfillings by endodontic plugger(18.2%) group(Table 1). Dandashi et al and  Reddy et al in their study found no significant differences between lentulospiral and endodontic plugger for obturation quality6,20.  Memarpour et al and Pandranki et al showed that lentulospiral group had better optimal filling than endodontic plugger which is in accordance to our result10,18. Findings in the present study is in accordance with an in-vitro C.B.C.T study conducted by Nagaveni et al, where they observed highest percentage of obturated volume in lentulospiral method compared to endodontic plugger, tuberculin and local anesthetic syringe21. Whereas Singh et al, found highest percentage of obturated volume with syringe systems (navitip and endodontic pressure syringe) compared to lentulospiral with slow speed handpiece, while least percentage of obturated volume was shown by insulin syringe on C.B.C.T evaluation5. In contrast to our study, Gandhi et al reported maximum underfills by lentulospiral technique in an in-vivo study with Ca(OH)2 obturation on comparing with pastinject and disposable syringe9. Lentulospiral gave optimal filling with minimum extrusions may be due to adequate flexibility of instrument and thicker consistency of mix or due to counter clockwise rotation of lentulospiral at predetermined length of canal rather than being pushed by pressure19,22. Insulin syringe has a thin non-flexible needle that reaches only to the middle 1/3rd of the canals and there by causing less fill of the material and comparatively more voids of larger size5,8.The more number of voids seen in lentulospiral in present study is in accordance with  various studies such as Vasishta et al and Gandhi et al whereas Peters et al found fewer voids in lentulospiral method compared to injection system with Ca(OH)2 obturation9,22,23. Memarpour et al showed more number of voids in endodontic plugger than lentulospiral technique which is contrary to our result10.An in-vivo study conducted by Pandranki et al reported no significant differences in number of voids between lentulospiral and endodontic plugger (31% voids in both techniques) on obturating with Endoflas18.. Hiremath et al, in his in-vitro study reported the second highest number of voids in insulin syringe system on comparing with various syringe systems like Jiffy tube, Endodontic pressure syringe and local anesthetic syringe with ZOE obturation3. The presence of voids in root canal fillings of primary teeth may provide pathways for leakage, leading to bacterial regrowth and infection. Voids in the apical or coronal portion or extending through the entire root canal length which increases the risk of endodontic therapy failure which may finally lead to retreatment1,5.Frequent presence of voids observed in lentulospiral technique is probably due to thicker consistency, smearing action of ZOE and repeated removal and reinsertion of the lentulospiral during the filling procedure. Since all the small irregularities in the canal cannot be completely obliterated, small air bubbles might get entrapped creating voids1,19. In syringe system as there is need to remove and reinsert the syringe repeatedly, which in turn may displace the paste, creates voids, and thus decrease filling quality. In addition, there is need to clean the syringe immediately after use which makes this method more complex and time-consuming10. In this study, on comparison of the mean number of voids in each one-third of root canal with R.V.G and C.B.C.T showed least number of voids in apical third and highest number of voids in middle third of root which was in agreement with the results of Memarpour et al10. In accordance with present study, Estrela et al also reported more number of voids in middle one-third1,10. In contrast to this, Singh et al and Peters et al studies showed more number of voids in coronal third than in the middle third1,23. The lower void formation in the coronal third in our study may be due to the finishing procedure of packing ZOE paste into the access cavity with a cotton pellet. Deveaux et al showed more number of voids in the apical third10. It has been observed that factors that influence the location and size of the voids include the type, viscosity, and consistency of the paste, the method used to apply the paste, and operator skill and experiences19.