Abstract
Introduction
The application of rotary instrumentation is successful in removing the smear layer and significantly decreasing the root canal microflora, along with superior and consistent obturation in primary teeth. The obturating materials are effective against resistant root canal microflora due to their antimicrobial properties. Aim : To evaluate and compare the combined effect of the type of instrumentation and obturating material on the outcome of pulpectomized primary molars.
Methods
A total of 288 selected primary molars were randomly divided into three treatment groups (Group KS, HS and MF), according to the type of instrumentation used for cleaning and shaping of the root canals. Each group consisted of 96 teeth. In the groups KS, HS and MF, root canal instrumentation was carried-out with Kedo-SG Blue pediatric rotary files, HERO Shaper rotary files, and manual NiTi K-files, respectively. Following instrumentation, these three groups were further subdivided into 3 subgroups consisting of 32 teeth each and obturated using zinc oxide eugenol, Endoflasยฎ, and DiaPex Plusยฎ. The quality of the root filling was assessed immediately and evaluated both clinically and radiographically over a two-year period.
Results
The quality of obturation was superior in the root canals instrumented with rotary file systems compared to manual files. The success rate was not statistically significant on the combination of different types of instrumentation file systems and obturating materials at the end of follow-up period.
Conclusion
The outcome of pulpectomized teeth is not significantly influenced by the advanced physical characteristics of rotary files and the chemical and biological qualities of the obturating materials.
1
Introduction
Endodontic treatment in primary teeth poses more challenges than in permanent teeth due to the anatomical complexities of their root canal systems, their closeness to the developing permanent tooth, the smaller size of the child’s mouth, and the difficulty in managing children’s behavior [ , ]. The intricate morphology of the root canal system in primary teeth complicates the achievement of thorough cleansing through manual instrumentation and irrigation of the root canals [ ]. Further, manual instrumentation is not only time-consuming but also prone to iatrogenic errors [ ].
To address these challenges in pediatric endodontics, an array of NiโTi automated files has been introduced to the market. These files offer several advantages, including better predictability, reduced instrumentation and obturation time, prevention of iatrogenic and/or procedural errors, greater reduction of root canal microflora, and less in-office stress for the child patient. They also result in superior and uniform obturation quality, less apical debris, and consequently less post-operative pain in primary teeth. Moreover, they reduce chair time and prevent fatigue for both the child and the pediatric dentist [ ].
The complex anatomy of the root canals in primary teeth makes it challenging to eliminate all microorganisms from the root canals by instrumentation alone. Therefore, an obturating material should be strongly antiseptic, in addition to its primary requirement of resorbing at a rate similar to that of the physiological primary root. The material should also be radio-opaque, non-toxic to the periapical tissue and tooth germ, easy to insert, and non-shrinkable [ ]. The obturating materials that are currently available commercially are zinc oxideโeugenol, iodoform-based pastes, and calcium hydroxide [ , ]. These are effective against resistant root canal microflora due to their antimicrobial properties, and they also provide an impervious hermetic seal [ ].
The success of pulpectomy treatment depends on the method and quality of instrumentation, irrigation, and disinfection, the type of obturating material, three-dimensional obturation of the root canal, the type of final restoration, and the number of visits [ , , ]. Previous studies have independently evaluated and compared the success of pulpectomized teeth that are instrumented with different file systems and obturated with different materials [ , , ]. However, there is no published data on the success of pulpectomized primary teeth evaluating the combined effect of the type of instrumentation and the material used for obturation. Therefore, the purpose of the present study was to evaluate and compare the combined effect of the type of instrumentation and obturating material on the outcome of pulpectomized primary molars. The null hypothesis was that the combined effect of the type of instrumentation and obturating material does not influence the outcome of pulpectomized primary molars.
2
Methods
2.1
Ethical considerations
The research protocol was approved by the Institutional Research Committee and the Institutional Ethics Committee (IEC/HIMS/RR173). The study adhered to the ethical principles for medical research as outlined by the World Medical Association’s Declaration of Helsinki and followed the CONSORT guidelines for the design and reporting of clinical trials in Pediatric Endodontics ( Figure-1 ).
2.2
Sample size calculation
The sample size was determined based on previously published studies [ , , , , ].
n=Z1โโ/22[P1(1โP1)+P2(1โP2)]d2
Where,
P1 = Proportion in the first group = 0.70 [Percentage of Optimum filling in Hero Shaper Rotary file system was 70%].
P2 = Proportion in the second group = 0.50 [Percentage of Optimum filling in Manual file system was 50%]
d [ ] = Population risk difference = 0.20.
1-ฮฑ = desired Confidence level = 95%
Z21-ฮฑ/2 = 1.96.
Power of Study = 0.80.
Margin of Error = 0.05.
The required sample size for each group was 93 teeth, which was rounded off to 96 teeth to ensure equal size distribution at sub-group level. In each group, the number of teeth (n = 96) were divided into 3 sub-groups (n = 32) based on 3 obturating materials used. Thus, 288 teeth were selected for the study purpose.
2.3
Selection of study participants
The study was a randomized, controlled, parallel clinical trial with three arms, focusing on treatment. The participants were healthy, cooperative children aged 4โ7 years who required endodontic treatment. Parents/legal guardians of the participating children were thoroughly informed about the study’s objectives, clinical procedures, treatment outcomes, and the risks and benefits of the procedure. After all their questions were answered, their informed written consent was obtained. Children aged over 6 years also gave their assent.
Each child participant was assigned an identification number to ensure confidentiality. Only the principal investigator had access to their records. Intraoral examinations were conducted, and standardized intraoral periapical radiographs were taken for teeth that might require pulpectomy.
2.3.1
Patient selection criteria
Children with special health care needs, those with limited or no cooperative abilities, those requiring sedation or general anesthesia for behavior management, and those with allergies to local anesthetics or any other drugs were excluded [ , ].
2.3.2
Clinical selection of the primary molars
Primary molars with deep carious lesions and pulp vitality, provoked or spontaneous pain unresponsive to analgesic drugs, no hemostasis within 5 min after pulpotomy, necrotic pulp, sinus tract, and other symptoms of irreversible pulpitis were included. Primary molars with inadequate structures for restoration, perforated pulpal floor, swelling (intraoral or extraoral), internal or external pathological root resorption, and excessive mobility were excluded [ , ].
2.3.3
Radiographic selection of the primary molars
Primary molars with radiolucent areas in the furcation or periapical region, at least two-thirds of each root remaining, absence of bone rarefaction, absence of internal or external resorption of more than 2/3 of the root, normal position of the underlying permanent teeth, intact lamina dura, and normal thickening of periodontal membrane were included. Teeth with mobility or rupture of the pericoronal follicle of the permanent successor, signs of internal or external pathological root resorption, and the presence of pulp canal obliteration were excluded [ , ].
A total of 353 teeth were screened for the study, and 288 teeth were selected.
2.4
Randomization
A total of 288 selected primary molars were randomly divided into three treatment groups according to the type of file systems used for cleaning and shaping of the root canals (Group KS- Kedo SG Blue pediatric rotary files, Group HS-HERO Shaper rotary file system, and Group MF- Manual NiTi K-files), each group consisting of 96 teeth. The assignment of teeth to the groups was done using a block randomization technique with varying block sizes, based on a computer-generated sequence provided by an independent researcher not involved in the study. The allocation process used serially numbered, opaque, and sealed envelopes (SNOSE), which were opened by someone other than the operator, immediately after determining the working length. Block randomization ensures equal selection chances, prevents allocation bias, and maintains an evenly distributed sample size at any given time [ , , ].
2.5
Specifications of the rotary file systems used
Kedo- SG Blue pediatric file system: This file system comprises of three NiโTi rotary files namely D1, E1 and U1. The total file length is 16 mm and working length of file is 12 mm along with variable taper corresponding to the diameter of primary root canals. D1 file has a tip diameter of 0.25 mm and are to be used in primary molars with narrow canals (mesial canals in mandibular molars and distobuccal and mesiobuccal canals in maxillary molars). E1 file has a tip diameter of 0.30 mm and can be used in wider molar canals (distal canal in mandibular molars and palatal canal in maxillary molars). U1 has a tip diameter of 0.40 mm and used in primary incisor teeth. The recommended rotation speed is 150โ300 rpm.
HERO Shapers file systems: HERO is an acronym for โHigh Elasticity in Rotation.โ Hero Shaper supplements the existing Hero 642. Compared with other rotary NiTi systems, Hero files have no radial lands but have a triple helix cross-section and a positive rake angle. The Hero Shaper files are supplied in ISO sizes of 20, 25 and 30, and in 0.4 and 0.6 tapers.
2.6
Interventions
The pulpectomy began with drying the injection site and applying a topical anesthetic. Local anesthesia (2% lignocaine, Lignox, Bangalore, India) was then administered, with an inferior alveolar nerve block for mandibular teeth and infiltration for maxillary teeth. Caries and overhanging enamel were removed with a #330 high-speed bur with water spray, and access to the pulp chamber was made using a #8 round bur. Coronal pulp was amputated with a spoon excavator, and radicular pulp was removed with H-files (Mani, Inc., Tochigi, Japan) [ ]. The pulpal remnants and dentinal debris were removed with copious irrigation with saline. The root canal’s patency was assessed, and the working length was determined by superimposing an endodontic instrument over the preoperative radiograph and keeping it 1โ2 mm short of the radiographic apex [ , , , ].
The randomization carried out by a study assistant who was blinded to the study, determined the endodontic files to be used for each child. In the KS, HS, and MF groups, root canals are cleaned and shaped with Kedo-SG Blue pediatric rotary files (Reeganz Dental Care Pvt. Ltd., India), HERO Shaper rotary file system, (Micromega, Geneva, Switzerland), and manual NiTi K-files, (Dentsply, Switzerland) respectively. In the KS and HS groups, the orifice of the root canal was enlarged using a coronal-enlarging file (Endoflareยฎ-Micromega, Geneva, Switzerland) before enlarging to the working length. Rotary files were operated with an endodontic motor(X-Smart, Dentsply Maillefer, OK, USA) at 300 rpm and 2.2-Ncm torque, with a lateral brushing motion and care was taken not to enter the root canal more than twice to avoid perforation [ , , ]. In the MF group, hand files were used, starting with the smallest size that meets resistance and enlarging up to three times the size of initial file, using the quarter-turn-and-pullback technique [ , ].
Each file was used on up to five teeth for consistency [ , ]. If resistance was met, no force was applied to minimize the risk of fracture [ ]. Root canals were prepared with intermittent irrigation of saline and a 17% EDTA gel (RC Help, Prime Dental Products, Pvt. Ltd.) as a lubricant [ , ]. After preparation, final irrigation with saline was performed, and the canals were dried with paper points.
Following, primary molars were further subdivided into three groups (KSZ/KSE/KSD, HSZ/HSE/HSD, MFZ/MFE/MFD), totaling 32 teeth per subgroup. Root canals were filled using zinc oxide eugenol cement (Zinc Oxide BP, Eugenol BP, Associated Dental Products Ltd.) in KSZ, HSZ, and MFZ subgroups, while Endoflasยฎ (Sanlor Laboratories S.A.S, Cali-Colombia) was used in KSE, HSE, and MFE subgroups. A uniform mixture of zinc oxide eugenol and Endoflasยฎ was prepared in a 1:1 powder-to-liquid ratio. A lentulospiral #25, cut to half its length for easier handling [ ], delivered the materials into the canals, with a rubber stopper ensuring the correct depth. DiaPlex Plusยฎ (DiaDent Group International, Korea), an iodoform paste, filled the canals in KSD, HSD, and MFD subgroups, applied via a pre-mixed syringe and extruded until visible in the pulp chamber [ ]. The access cavity was restored with type II glass ionomer cement (GC, India).
Post-pulpectomy, stainless steel crowns (3 M ESPE, St. Paul, MN, USA) were placed within a week, in a separate session to suit younger patients and standardize treatment. Participants were instructed to report any post-procedure symptoms. All children received comprehensive dental care, regardless of their participation in the study. The pulpectomy procedures were conducted in a single visit by an experienced operator, using strict aseptic techniques and following manufacturer protocols to ensure uniformity across all cases.
2.7
Evaluation of quality of obturation
Postoperative intraoral radiographs were taken to evaluate the quality of obturation by two pediatric dentists who were unaware of the type of instrumentations and obturating materials used. The kappa test scores for inter-examiner and intra-examiner agreement were 0.86 and 0.93, respectively. Each radiograph was categorized as underfilled, optimally filled, or overfilled [ , ] ( Figs. 2โ4 ). Disagreements defaulted to the lower ranking of filling.
2.8
Evaluation of outcome of pulpectomized teeth
Pulpectomized teeth underwent clinical and radiographic assessments every three months for two years. High kappa scores indicated strong examiner agreement, with disagreements resolved through discussion or marked as failures. A pulpectomy was considered clinically successful if there were no symptoms such as pain, tenderness to percussion, gingival swelling, sinus tract formation, or abnormal tooth mobility [ , ]. Similarly, a pulpectomy was considered radiographically successful if there was no increase in the size of pre-operative furcal or periapical radiolucency, development of new radiolucency on subsequent follow-ups, or development of internal or external root resorption, changes in lamina dura/width of periodontal ligament space, and deviation in the path of succedaneous tooth eruption. Further, the radiographic examination also included the resorption of intraradicular material and extraradicularly extruded materials [ , ]. The clinical and radiographic success was determined independently as not all radiographic failures are associated with clinical symptoms and vice versa [ , , ]. Blinding was maintained for all except the operator, due to the recognizable nature of the materials used.
2.9
Statistical analysis
Statistical Package for Social Sciences [SPSS] for Windows Version 22.0 Released 2013. Armonk, NY: IBM Corp., was used to perform statistical analyses. Descriptive Statistics: Descriptive analysis of all the explanatory and outcome parameters was done using frequency and proportions for categorical variables, whereas in Mean & SD for continuous variables. Inferential Statistics: The Chi-Square Test was used to compare the distribution of study participants according to age and gender, radiographic findings based on type of instrumentation and obturating materials at different time intervals, quality of obturation, and outcome of pulpectomized teeth based on type of Instrumentations and obturating materials at different time intervals and to correlate the type of instrumentations, obturating materials, quality of obturation with outcome of pulpectomized teeth. The level of significance was set at P < 0.05.
3
Results
The study involved 288 children (102 males and 186 females) aged between 4 and 7 years, with an average age of 5.31 ยฑ 1.09 years. Both maxillary and mandibular first and second molars were treated in equal numbers. There were no dropouts during any of the evaluation periods.
3.1
Quality of obturation
In the teeth instrumented with KS files and obturated with zinc-oxide eugenol, Endoflasยฎ and DiaPex Plusยฎ, 24 (75%), 27 (84.4%) and 23(71.9%) teeth were optimally filled, respectively. In the teeth instrumented with HS files and obturated with zinc-oxide eugenol, Endoflasยฎ and DiaPex Plusยฎ, 22 (68.8%), 25 (78.1%) and 23(71.9%) teeth were optimally filled, respectively. In teeth instrumented with MF and obturated with zinc-oxide eugenol, Endoflasยฎ and DiaPex Plusยฎ, 17 (53.1%), 18 (56.3%) and 17(53.1%) teeth were optimally filled, respectively ( Table 1 ).
| Quality of obturation | Kedo-SG files (n = 96) | HERO Shapers files (n = 96) | Manual files (n = 96) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| ZOE (n = 32) n(%) | EF (n = 32) n(%) | DP (n = 32) n(%) | ZOE (n = 32) n(%) | EF (n = 32) n(%) | DP (n = 32) n(%) | ZOE (n = 32) n(%) | EF (n = 32) n(%) | DP (n = 32) n(%) | |
| Underfilled | 3 (9.4) | 2 (6.3) | 3 (9.4) | 2 (6.3) | 2 (6.3) | 1 (3.1) | 11 (34.4) | 10 (31.3) | 10 (31.3) |
| Optimally filled | 24 (75) | 27 (84.4) | 23 (71.9) | 22 (68.8) | 25 (78.1) | 23 (71.9) | 17 (53.1) | 18 (56.3) | 17 (53.1) |
| Overfilled | 5 (15.6) | 3 (9.4) | 6 (18.8) | 8 (25) | 5 (15.6) | 8 (25) | 4 (12.5) | 4 (12.5) | 5 (15.6) |
| P-value | <0.001* | <0.001* | 0.99 | ||||||
The quality of obturation according to the combined effect of type of instrumentation file systems and type of obturation materials was not statistically significant. On multiple comparison, the teeth in group KS and HS rotary files showed significantly superior obturation quality compared to group MF (p โค 0.001). However, obturation quality did not significantly differ between groups KS and HS (p โค 0.33). The obturation quality did not show a statistically significant difference between all three obturating materials ( Table 2 ).
| Instrumentation file systems | Obturating materials | |||||
|---|---|---|---|---|---|---|
| Groups | Kedo SG Vs HERO Shapers | Kedo SG Vs Manual files | HERO Shapers Vs Manual files | ZOE Vs EF | EF Vs DP | DP Vs ZOE |
| p-value | 0.33 | <0.001* | <0.001* | 0.63 | 0.68 | 0.59 |
3.2
Radiographic evaluation of pulpectomized teeth
The evidence of radiographic failure was not observed in any of the three groups (KS, HS, and MF) until the end of 9 months. However, from the 12th month onwards, radiographic failure was seen in the MF group, and subsequently in all three groups. By the end of the follow-up period, a total of 7 teeth with furcal radiolucencies, 7 teeth with periapical radiolucencies, and 5 teeth with changes in the lamina dura were observed. The comparisons of radiographic failures between the groups were not statistically significant differences ( Table 3 ).
| Follow-up | Radiographic findings | Kedo-SG files n = 96 n(%) |
HERO Shapers files n = 96 n(%) |
Manual files n = 96 n(%) |
||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ZOE n = 32 n(%) |
EF n = 32 n(%) |
DP n = 32 n(%) |
ZOE n = 32 n(%) |
EF n = 32 n(%) |
DP n = 32 n(%) |
ZOE n = 32 n(%) |
EF n = 32 n(%) |
DP n = 32 n(%) |
||
| Radiographical evaluation | ||||||||||
| 12-Mon | FR | โ | โ | โ | โ | โ | โ | โ | โ | โ |
| PR | โ | โ | โ | โ | โ | โ | โ | โ | โ | |
| PDL | โ | โ | โ | โ | โ | โ | 1(3) | โ | โ | |
| 15-Mon | FR | 1(3) | โ | โ | โ | โ | โ | 1(3) | โ | โ |
| PR | โ | โ | โ | โ | โ | โ | โ | 1(3) | โ | |
| PDL | โ | โ | โ | โ | โ | โ | โ | โ | 1(3) | |
| 18- Mon | FR | โ | โ | โ | 2(6) | โ | โ | 1(3) | โ | โ |
| PR | โ | 1(3) | โ | โ | โ | 1(3) | 1(3) | โ | โ | |
| PDL | โ | โ | โ | โ | โ | โ | โ | โ | 1(3) | |
| 24-Mon | FR | โ | โ | 1(3) | โ | โ | 1(3) | โ | โ | โ |
| PR | โ | โ | โ | 1(3) | โ | โ | 1(3) | 1(3) | โ | |
| PDL | โ | โ | โ | โ | 1(3) | โ | โ | โ | 1(3) | |
| Total | Failures | 1(3) | 1(3) | 1(3) | 3(9) | 1(3) | 2(6) | 5(16) | 2(6) | 3(9) |
| Success | 31(97) | 31(97) | 31(97) | 29(91) | 31(97) | 30(94) | 27(84) | 30(94) | 29(91) | |
| p-value | 0.37 | 1.00 | 0.36 | |||||||
| Fate of obturating materials | ||||||||||
| 9-Mon | IR | โ | โ | โ | โ | โ | 1 | โ | โ | 1 |
| REM | โ | 1 | 3 | โ | 1 | 4 | โ | 1 | 1 | |
| 12-Mon | IR | โ | โ | 1 | โ | โ | โ | โ | โ | โ |
| REM | โ | 1 | 1 | โ | 1 | 1 | โ | 1 | 1 | |
| 15-Mon | IR | โ | 1 | โ | โ | 1 | โ | โ | โ | |
| REM | โ | โ | 2 | โ | 2 | 3 | โ | 1 | 3 | |
| 18-Mon | IR | โ | โ | 1 | โ | โ | โ | โ | โ | 1 |
| REM | โ | 1 | โ | 1 | โ | โ | 1 | |||
| 24-Mon | IR | โ | โ | โ | โ | โ | 1 | โ | 1 | |
| REM | โ | โ | โ | โ | โ | โ | โ | โ | โ | |
| Total | IR-09 | โ | โ | 03 | โ | – | 03 | โ | 03 | |
| REM-31 | โ | 03 | 06 | โ | 05 | 08 | โ | 04 | 05 | |
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