Obturation Techniques in Primary Teeth

Dental caries is a global concern affecting children and adults. A pulpectomy is considered to be the treatment of choice to preserve the pulpally involved primary teeth. Among the various factors determining the clinical success of pulpectomy, proper obturation of the root canals plays an important role. Different obturation materials are being used for the obturation of the primary teeth root canal, which includes zinc oxide eugenol, calcium hydroxide, calcium hydroxide iodoform paste and combinations. These materials are available in different forms such as powder, powder and liquid, paste forms. Various techniques are available to introduce the obturation materials into the root canal systems. These techniques have been tried to create a three-dimensional (cid:977)luid-tight seal of the root canals. This review article aims to high-light the different techniques that are being used for the obturation of primary teeth. Each technique has its advantages and disadvantages. Creation of voids within the obturation, under(cid:977)illing or over(cid:977)illing are the common problems that can be encountered during root canal obturation. These factors can com-promise the clinical and radiographic success of pulpectomy treatment. With the current evidence, no de(cid:977)initive conclusions can be made to decide which is the best obturation technique in terms of clinical and radiographic success. The choice of technique selection depends on the clinician’s preference, cost-effectiveness, time consumption, ease of handling.


INTRODUCTION
One of the primary concern in the ield of Paediatric dentistry is the early loss of primary teeth. Premature loss of primary teeth results in space loss which affects the integrity of oral tissues, swallowing, mastication and speech (Fuks, 2000). A pulpectomy is considered to be the ideal treatment to preserve the primary teeth with pulpal involvement (Rodd et al., 2006).
A pulpectomy is the process of complete removal of the pulp from the root canals of the primary teeth and illing them with an inert resorbable material for maintaining the tooth in the dental arch till the time of their exfoliation (Fuks, 2008).
The characteristic features of ideal pulpectomy (Lin et al., 2006)  The three-dimensional hermetic seal of the root canal system is an essential factor that determines the success of pulpectomy. It affects microleakage and cuts off the nutrient supply to any surviving microorganism and prevents the entry of bacterial products into the periapical tissues (Singh et al., 2017).
There are several techniques available in the literature that have been used for introducing obturating material into the root canal. The ultimate goal of any obturation technique is to obtain a complete illing of the root canals from the canal ori ice until the root apex with minimal or no voids (Guelmann et al., 2004). Also, the obturation technique should be easy to use, less time consuming and should have a consistent result (Sevekar et al., 2011).

Endodontic Pressure Syringe
The Endodontic pressure syringe apparatus consists of a syringe barrel, threaded plunger, wrench and threaded needle. The pressure syringe acts by a screw mechanism. The needle is inserted into the root canal until the resistance is obtained. A slow, withdrawing-type of motion with a quarter turn at 3 mm intervals was used until the canal is visibly illed at the ori ice (Aylard and Johnson, 1987). As the needles are lexible, it can be used in the tortuous canals (Sevekar et al., 2011). Over illed obturation is common with pressure syringe.
In the study by Hiremath and Srivastava, endodontic pressure syringe performed the best with a maximum number of optimal illings compared to insulin syringe, jiffy tube, and local anaesthetic syringe (Hiremath and Srivastava, 2016). Aylard and Johnson reported signi icantly better results with endodontic pressure syringe when compared with the mechanical syringe for obturating the curved root canals (Aylard and Johnson, 1987). Practical dif iculties in adjusting the rubber stopper and need to clean the syringe immediately after every use make this method complex and timeconsuming (Memarpour et al., 2013).

Mechanical Syringe
This technique introduced by Greenberg in 1971, utilizes a plunger system. This technique showed poor performance in both curved and straight canals (Aylard and Johnson, 1987).

Tuberculin Syringe
In 1987, Aylord and Johnson used Tuberculin syringe for the obturation of the root canal. 26gauge, the 3/8-inch needle was used, and a slow inger pressure was applied onto the plunger to express the material into the canal (Aylard and Johnson, 1987). The wet cotton pellet was recommended to gently push the illing materials into the root canals (Sevekar et al., 2011). Tuberculin syringe group produced poor results in primary molar teeth obturation (Memarpour et al., 2013).
Needle separation during injection of the material was the main drawback of this technique. This necessitated the need for replacing the needle repeatedly leading to the formation of voids (Memarpour et al., 2013).

Insulin Syringe Technique
This technique was irst described by (Priya, 2011). The needle is inserted into the canal and is kept 2mm short of apex. The material is expressed into the canal, as the needle is gradually retrieved, thereby avoiding voids. Addition of more material was done by placing the material over the ori ice and is compressed using wet cotton. Optimal illing with less number of voids can be achieved with optimum operator skills and proper material mix (Priya, 2011). (Akhil et al., 2019) stated that insulin syringe produced least voids when compared to endodontic plugger and lentulo spiral.

Disposable Injection Technique
This technique utilizes 2-ml syringe and 24-gauge needle-a stopper adjusted to measured working length. The material is expressed into the root canal similar to insulin syringe technique. This technique is considered to be cost-effective and straightforward (Bhandari et al., 2012).

NaviTip
NaviTips, introduced by Ultradent, is a thin and lexible metal tip used to deliver sealers into the root canals. (Guelmann et al., 2004) stated that NaviTips offered more desirable obturation than the obturation with a syringe with plastic needle (Vitapex), lentulo spirals. (Memarpour et al., 2013) concluded that NaviTip produced the best results. NaviTips showed poor results when compared to Endodontic Plugger and lentulo spirals when Endo las was used (Pandranki et al., 2017). Khubchandani reported that Navitip controlled voids production and produced the best apical seal (Khubchandani et al., 2017).

Endodontic Plugger
Gould irst used the technique of using endodontic plugger for obturation of primary teeth in 1972, and the technique is called an Incremental illing technique. An endodontic plugger, to the size of the previously used ile, was used. The rubber stopper is adjusted 2mm short of the apex. Additional increments were added until the canal is illed until the cervical area (Dandashi et al., 1993). The disadvantage of Endodontic plugger is its limited lexibility, and it does not produce good obturation in narrow and curved canals. Also, repeated insertion of the instrument can lead to large voids. (Memarpour et al., 2013) also found that packing with plugger causes more voids.

Reamer
A reamer is inserted into the root canal using a vibratory motion with clockwise rotation. It is then withdrawn from the canal while continuing the clockwise motion. A rubber stopper was adjusted at the predetermined working length. The process was repeated until the canal ori ice appeared illed with the paste. The results were similar to that produced with an insulin syringe (Priya, 2011).

Jiffy Tube
Rif icin in 1980 popularized the technique of using Jiffy tube. The tip is placed into the canal ori ice, and a downward squeezing motion is used to express the material until the ori ice appears to be illed (Aylard and Johnson, 1987).

PastInject
PastInject (MicroMega, France) has lattened blades, thereby facilitating easy and effective placement of material into the root canal. (Grover et al., 2013) found that PastInject was more comfortable to be used and produced good results of maximum optimally illed canals and with minimal voids.

Lentulospiral
Kopel in 1970 popularized the technique of obturation using Lentulospiral. (Aylard and Johnson, 1987;Dandashi et al., 1993) concluded that the engine-driven lentulo spiral produced best results and there was no signi icant difference between the lentulo spiral and the pressure syringe when used in straight canals. For illing of the apical canal, lentulo spiral at 15000 rpm and for illing of apical and the middle third, lentulo spiral at 5000 rpm was suggested (Deonízio et al., 2011). There was no statistically signi icant difference between the enginedriven lentulo spiral and hand-held lentulo spiral. Highest optimally illed canals were observed in a lentulo spiral when compared to endodontic plugger and insulin syringe (Akhil et al., 2019).
Hand-held lentulo spiral showed maximum post obturation volume followed by engine-driven lentulo spiral (Nagaveni et al., 2017). Effective in obturation of narrow and curved canals due to lexibility of the Lentulospiral. Instrument fracture, over obturation and dif iculties in adjusting the rubber stops, are the major disadvantages of using this technique. (Memarpour et al., 2013)

Bi-Directional Spiral
Dr. Barry Musikant introduced the bidirectional spiral in 1998. Spirals at the coronal end push the material towards the apex and the spirals at the apical end towards the coronal end. At the junction, the material is thrown out laterally. This controls the extrusion of the material beyond the apex. Bidirectional spiral produces a considerable number of voids (Grover et al., 2013). Bi-directional spiral and lentulo spiral produced better results than incremental technique, and past injects and the bidirectional spiral was superior to lentulo spiral in the prevention of over obturation (Chandrasekhar et al., 2018).

CONCLUSIONS
There are different obturation techniques available, each with their pros and cons. Clinician's preference can vary based on cost-effectiveness, time consumption, ease of handling. Therefore, no de initive conclusions can be made to decide which is the best obturation technique.