Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2017  |  Volume : 28  |  Issue : 2  |  Page : 175--180

Volumetric analysis of root filling with cold lateral compaction, Obtura II, Thermafil, and Calamus using spiral computerized tomography: An In vitro Study


Divya Jindal, Medhavi Sharma, Deepak Raisingani, Anupama Swarnkar, Mridu Pant, Rachit Mathur 
 Department of Conservative Dentistry and Endodontics, Mahatma Gandhi Dental College and Hospital, Jaipur, Rajasthan, India

Correspondence Address:
Mridu Pant
Flat No. 203, Plot No. 20, Emerald Greens Society, Sector 52, Gurgaon, Haryana
India

Abstract

Aim: The aim of the present study is volumetric analysis of root canal filling with cold lateral compaction, Obtura II, Thermafil, and Calamus using spiral computerized tomography (SCT). Materials and Methods: Root canals of eighty mandibular premolars were instrumented using rotary ProTaper, and the volume of the canal space was measured using spiral computerized tomography (SCT). The teeth were divided into four groups of twenty teeth each, and root canals filled by lateral compaction technique, Thermafil carriers, Obtura II, and Calamus techniques, respectively. AH Plus was used as a sealer with all techniques. The filled volume in each canal was measured using SCT, and the percentage of obturated volume (POV) was calculated. The data were statistically analyzed using ANOVA, Kruskal–Wallis test, and Mann–Whitney U-test. Results: The four groups were comparable in canal volume. The overall POV was 78.11%, 85.72%, 82.50%, and 87.89% for lateral compaction, Thermafil, Obtura II, and Calamus, respectively (P < 0.05). Conclusion: The greatest POV was obtained with Calamus and Thermafil. Voids were seen in all root fillings.



How to cite this article:
Jindal D, Sharma M, Raisingani D, Swarnkar A, Pant M, Mathur R. Volumetric analysis of root filling with cold lateral compaction, Obtura II, Thermafil, and Calamus using spiral computerized tomography: An In vitro Study.Indian J Dent Res 2017;28:175-180


How to cite this URL:
Jindal D, Sharma M, Raisingani D, Swarnkar A, Pant M, Mathur R. Volumetric analysis of root filling with cold lateral compaction, Obtura II, Thermafil, and Calamus using spiral computerized tomography: An In vitro Study. Indian J Dent Res [serial online] 2017 [cited 2021 Nov 30 ];28:175-180
Available from: https://www.ijdr.in/text.asp?2017/28/2/175/207785


Full Text



 Introduction



Root canal obturation involves the three-dimensional (3D) filling of the entire root canal system and is a critical step in endodontic therapy. There are two purposes of obturation that is elimination of all avenues of leakage from the oral cavity or the periradicular tissues into the root canal system and sealing within the root canal system of any irritants that remain after appropriate shaping and cleaning of the canals, thereby isolating these irritants. The introduction of thermoplastic gutta-percha (GP) to dentistry in the mid-19th century was a turning point in endodontic treatment. Plasticity combined with physical durability made it possible for the material to move into the recesses of the root canal system and to adapt to the canal walls.[1]

Quality of root fillings can be assessed by various experimental methods such as radioisotope, dye penetration, fluid filtration, bacterial leakage, microscopic analysis, clearing techniques, and Micro computerized tomography. It has been reported that spiral computerized tomography (SCT) has been a useful tool in various in vivo and laboratory studies. It was stated that with SCT, 3D volume measurements are possible without sectioning specimens, thus avoiding loss of material.[2]

Hence, the aim of this study was to assess and compare the total percentage of volume (POV) of the root canal filled with GP, as well as POV at three different levels – coronal, middle, and apical third of root canals, obturated with cold lateral condensation, Thermafil, Obtura II, and Calamus techniques using SCT.

 Materials and Methods



Specimen preparation

This study sample comprised eighty extracted, permanent single-rooted human teeth, which were selected, cleaned of extraneous tissue and calculus, and then disinfected by 5.25% sodium hypochlorite for 2 weeks. Subsequently, the teeth were decoronated at the cementoenamel junction (CEJ) and stored in deionized water before instrumentation.

Tooth preparation

Access cavity preparation was carried out using #2, #4 round carbide burs to establish an initial outline form. The remaining pulp was removed, and the working length was determined by introducing a size 10 K-file (Dentsply Maillefer) into the canal until it could be seen at the apical foramen.

The canals were prepared using ProTaper nickel–titanium rotary files (Dentsply Maillefer Ballaigues, Switzerland). The canals were irrigated between each file with 2 ml of 5.25% NaOCl. A size 15 K-file was introduced to maintain patency of the apical constriction. The canals were all prepared to a F2 ProTaper file. In between, recapitulation was carried out using #15 K-file. After completion of the preparation, all specimens were irrigated with 5 ml of 5.25% NaOCl for 60 s and dried with paper points (Dentsply/Maillefer). Teeth were then randomly distributed into four groups of twenty each and were mounted on wax.

Specimens were scanned using SCT (Siemens). They were then viewed under high resolution, both cross-sectionally and longitudinally with a constant thickness of 0.5 mm/slice and a constant spiral or table speed of 0.5 and 140 kVp [Figure 1] and [Figure 2]. The scanned data were then transferred to Syngo (Siemens) image analysis and evaluated. The area of prepared root canal in each slice was measured from CEJ to the apex of the root. The volume of root canal in each slice was calculated by multiplying the root canal area by the slice thickness (0.5 mm). Finally, the volume of each canal was calculated. The root length was divided into three equal parts; coronal, middle, and apical thirds, and the volume of each segment was calculated separately. AH Plus was used as the sealer.{Figure 1}{Figure 2}

Group I: Cold lateral compaction

The process included first checking the size F2 cone fitted with tugback. Sealer (AH Plus) was introduced into the canal with a lentulospiral. The master apical cone tip was dipped in sealer and then seated apically. The accessory cones were compacted 1 mm short of working length. No vertical compaction was performed.

Group II: Thermafil obturation technique

Thermafil obturator of the same size as the size verifier that fitted passively at working length was selected. A rubber stop was adjusted to coincide with the working length taken from the root. A thin layer of sealer was placed at the coronal orifice; the Thermafil obturators were heated in the ThermaPrep oven as per manufacturer's instructions, and the thermoplasticized GP was delivered into the canals. The carrier was stabilized with the index finger, and after GP was cooled, the carrier was cut using a round bur.

Group III: Obtura obturation system

A 20-gauge Obtura (Obtura Spartan, Fenton, MI, USA) needle tip was selected. The tip was inserted into the canal 3–5 mm short of the working length. The temperature was set at 200°C, the trigger was pressed so that the molten GP flowed, and the tip was withdrawn slowly out of the canal. The apical segment was compacted using appropriate Obtura Pluggers. Backfilling was achieved by the application of thermoplasticized GP in 4–5 increments, followed by uniform compaction with pluggers.

Group IV: Calamus obturation system

The master cone was lubricated lightly with sealer and gently inserted to length. The Calamus Electric Heat Plugger was activated and utilized to sear off the master cone at the CEJ. This plugger was used with short, firm vertical strokes to scrape warm GP off the canal walls and flatten the material coronally. The working end of the plugger was used to vertically press on this flattened platform of warm GP for 5 s. Calamus backfill was performed by positioning the tip of the warm cannula against the previously packed GP material for 5 s. For backfill, the flow handpiece was activated, and 3–4 mm segment of warm GP was dispensed into the canal. The backfill technique was continued in the manner described until the canal was completely filled.

A second SCT scan was performed to determine the volume of GP and sealer. POV in each tooth was calculated. POV in the coronal, middle, and apical thirds for each tooth was calculated separately.

Statistical analysis

Statistical analysis was performed with nonparametric tests (ANOVA, Kruskal–Wallis, and Mann–Whitney U-test). The level of significance was set at P< 0.05.

 Results



The volume (mean and standard deviation) of root canals after cleaning and shaping for each group is given in [Table 1]. The four groups were statistically comparable in respect of canal volume (P > 0.05). All POV values are summarized in [Table 1]. The Calamus and Thermafil gave the highest POV values and were significantly different in comparison with Obtura II and lateral compaction (P [3] The final objective of endodontic procedures should be the total obturation of the root canal space.[4] Biologic necessity requires the elimination of the protein degradation products, bacteria, and bacterial toxins which emanate from necrotic and gangrenous root canals. While these irritants may be eliminated by extraction of the tooth, the health of the dentition is secured more soundly if they are eliminated by the cleaning and shaping and total obturation of the root canal system. In the final analysis, it is the sealing off of the complex root canal system from the periodontal ligament and bone which insures the health of the attachment apparatus against breakdown of endodontic origin.[5]

Traditional methods of evaluating root fillings have disadvantages. On sectioning the root, there could be a loss of material which might mimic voids. Radiographs give only two-dimensional interpretations. The time taken for fluid filtration and clearing techniques may be a concern. Dye penetration studies do not correlate clinically, whereas dye extraction studies evaluate only the apical third of the tooth.[6] Bacterial leakage studies do not simulate exact clinical conditions, need long periods of observation, and do not allow quantification of the number of penetrating bacteria.[7],[8] A literature search revealed that only sectioning studies have been undertaken to assess thermoplasticized root fillings at various levels.[2] SCT, a noninvasive technique, gives a 3D interpretation at various levels, avoids loss of material, yields reproducible results, and the specimens can be used for further research. The specific location of voids can be determined accurately.[9],[10]

In this study, Calamus and Thermafil gave the highest overall POV. The reason could be that the use of heat-softened GP had created a better homogeneous mass with less voids and better adaptation of the GP to the canal wall, whereas cold lateral compaction gave the least POV.[11]

Overfilling is the most common concern expressed about using the Obtura system [Figure 3]. Pressure should be applied only on the softened GP but not on canal walls during condensation. The tapered preparation enhances the flow of the plasticized material, whereas the Coke bottle preparation negates the flow. While attempting to provide a hermetic seal, we have to keep in mind that when heated GP cools, always there is contraction.[12]{Figure 3}

Lateral compaction had 78.1% of overall filling, the lowest value of all the fillings [Figure 4]. This was mainly because this technique does not produce a homogeneous mass and may leave spaces between the GP and the dentinal walls or accessory cones. The accessory and master cones are laminated and remain separate from each other. Sometimes, the sealer fills the space between the cones, often depicting a denser root fill. Sequential injection and then multiple compactions of warm GP compensate for the contraction of GP that takes place on cooling and hence creates a dense obturation.{Figure 4}

Group IV (Calamus obturation system) [Figure 5] showed the maximum POV. This comparatively newer system is based on the principle of warm vertical compaction where the objective is to continuously and progressively carry a wave of warm GP along the length of the master cone, starting coronally and ending in apical corkage. This method advantageously serves to initially thermosoften the master cone, maximizes the volume of GP, and effectively increases hydraulics during obturation. It utilizes different sizes manual pluggers with different working end diameters to compact GP efficiently to the canal walls.[13] The consistent flow of the Calamus unit does make the obturation of curve quicker and easier. The warm GP needs to be compacted as it cools to overcome any shrinkage that will normally occur. Since the softness of the GP is mass dependent, the GP at the orifice level has the greatest mass and will stay softest for the longest time in the canal, regardless of which technique is utilized.{Figure 5}

Thermafil produces a homogeneous 3D obturation [Figure 6]. It allows simple, fast, and predictable fillings of root canals, especially useful for small curved canals. Thermafil technique requires minimal compaction only in coronal end, so it produces few strains during compaction of GP. It easily flows around curves and canal irregularities providing a greater density of GP at the apical portion of the filling. Thermafil technique leaves a plastic carrier in the canal which poses a problem if post is required or the case has to be retreated. Special oven (ThermaPrep plus oven) is required to heat thermafil cones. In curved canals, carrier usually gets stripped of GP in curvature.[14],[15]{Figure 6}

When comparing the POV of coronal, middle, and apical thirds of lateral compaction, Thermafil, Obtura, and Calamus techniques, there was a difference in the efficacy of fillings. It was seen that the POV of coronal third was slightly more than apical third [Figure 7]. Even though pluggers were used in case of Obtura for coronal compaction and lack of additional vertical condensation with pluggers in the Thermafil group, there was a decrease in efficacy. This could be due to the mismatch in taper of the instrument to that of the enlarged canal orifice.{Figure 7}

 Conclusion



The aim of obturating the root canal system is to perfectly seal the root canal space to prevent penetration of bacteria and their products into the periradicular tissues and create a favorable biological environment for healing of periapical tissues to take place. A hermetic 3D obturation of the root canal system is one of the conditions under which long-term successful root canal therapy can be achieved. Voids created by inadequate fusion of the GP cones; penetration of bacterial toxins and their flow into periapical tissue from oral cavity jeopardize the endodontic treatment success.

Voids were seen in all the root fillingsCalamus obturating technique showed the least spaces or voidsLateral compaction produced the maximum spaces or voidsWarm vertical compaction exhibited least voids than cold lateral compaction.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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