Radiographic Assessment of the Quality of Root Canal Filling of Mandibular First Molars Performed by Endodontists in Asir Region, Saudi Arabia

BACKGROUND

The aim of non‐surgical root canal treatment is to prevent or/and treat apical periodontitis, and it is at the center of the discipline of endodontics.¹ The quality of root canal fillings (RCFs) is of utmost importance in ensuring successful outcomes for patients; good quality relies on the proper cleaning, shaping, and obturation of the root canals to prevent periapical inflammation and to provide a good environment for healing of any apical inflammation.² Teeth with inadequate RCFs reveal the presence of periapical pathosis.³ Thus, failure to adequately fill and seal the root canals can lead to reinfection and treatment failure.

The assessment of RCF outcomes involves employing clinical and radiological examinations. Three key factors that determine the quality of RCF are length, density, and taper. Length refers to the accurate measurement and instrumentation at the apex of the root, while density relates to the compactness and uniformity of the filling material within the canal space, and taper related to the gradual reduction in diameter from coronal to apical portions.^4–6

The first permanent molars are the teeth that erupt early in the oral cavity, and they are most susceptible to dental caries.⁷ Molars are mostly treated teeth and they are often subjected to infections and tooth decay. In addition, performing endodontic procedures on molars poses greater challenges compared with root filling on any other single-rooted teeth because of various factors such as increased complexity of molar anatomy and their position in the patient’s mouth.^8,9 Therefore, the expertise of an endodontist is crucial.

Endodontists undergo additional years of training specifically focused on endodontic procedures. Thus, they frequently handle complex or challenging cases that may require advanced skills in RCF.¹⁰ In the last 20 years, notable advancements have been made in technology, materials, and procedures related to endodontic treatment. These achievements encompass various improvements, such as microscopy, rotary nickel titanium files, ultrasonics, improved irrigation solutions and technologies, digital radiography, and bioceramics.^4,11,12

Bioceramic sealers have gained prominence in endodontics because they offer superior sealing abilities and biocompatibility due to their hydrophilic nature, tolerance of residual moisture in the canal, and bioactive properties.¹³ Thus, it results in minimizing leakage and enhancing periapical healing.¹⁴ When combined with a single-cone technique that matches the size and shape of the prepared root canal used for obturation can further enhance the quality of RCF.¹⁵ Cold hydraulic obturation involves using hydraulic pressure to distribute the sealer evenly throughout the root canal system while minimizing the risk of extrusion or overfilling.¹⁶

As mentioned in most previous studies, periapical radiographs are used to assess the quality of RCF.^17–22 Recent studies compared success rates of RCFs performed by endodontists vs general dentists. An unacceptable quality of RCFs performed by GDPs has been reported by Bajawi et al. and Silnovica in SA and Sweden,^17,18 but an acceptable quality of RCTs of GDPs and endodontists has been obtained by Al-Obaida in SA, Laukkanen in Finland, Pietrzycka in Poland, and İnce Yusufoglu in Turkey.^19–22 The findings of these studies have revealed high success rates among specialists, shedding light on the significance of expertise in this aspect of dental care.

Given the lack of the quality of RCF studies among Saudi endodontists in all cities, particularly in the southern region of Saudi Arabia, this radiographic cross-sectional study aimed to evaluate, assess, and compare the quality of RCF done to mandibular first molar teeth performed by endodontists in this region. The following criteria were used: the degree of qualification type, side of the mandibular arch, operator experience, and canal locations.

PARTICIPANTS AND METHODS

RESULTS

A total of 74 mandibular left and right molars with 224 filled canals were assessed in this cross-sectional radiographic study. The patients’ ages were between 18 and 44 years, with a mean age and standard deviation of 21.83 ± 6.446 years. Half of them were males and with treated mandibular first molar on the right side, and 54% of the operators had less than 5 years of experience. Similar percentages without radiographical abnormality were detected in relation to the canal apex. Almost equal percentages (33%) for the number of MB, ML, and distal canals were recorded (Fig. 2). A total of five endodontists performed the RCF of all the canals; three of them were males with a Saudi board certification in endodontics. Percentages of 77, 93, and 91% were recorded for the quality of RCF parameters (taper, density, and taper), respectively. The overall quality of RCF was 87% of the acceptable parameters (Fig. 3).

The Chi-square and Fisher’s exact tests were used to generate OR and 95% CI to compare the quality of RCF with the parameters assessed. Table 2 shows the association or relation of RCF quality with the holder certificate type of the operators. Adequate length, density, and taper recorded almost equal percentages among the Saudi and non-Saudi board holders, with slightly higher percentages in length and 81.6 and 74.3% in relation to non-Saudi and Saudi board certificate holders, respectively. No significant differences were recorded in the three parameters with p-value between 01.64 and 0.223. The percentage of adequate RCF length in the right side was slightly higher than that in the left side (79.3–74.3%), whereas the density and tapers were slightly higher in the left side (94.7% in comparison with 91.0 and 86.5% for the right side). Only taper showed a significant difference when we compared the left and right sides for RCF quality of the treated lower first molars (OR = 0.4, 95% CI: 0.1–0.9, p = 0.035), as given in Table 3.

Almost similar percentages of adequate RCF length and taper were obtained for both groups with operators’ experiences in less than 5 years at 76.8 and 90.4%, respectively. The quality of adequate density of RCFs with operators with less than 5 years of clinical experiences was slightly higher than that of the other group, with a recorded rate of 96.0%. By contrast, the group with 5 or more years of experience had a rate of 88.9%. We found a significant difference between the two groups in this parameter, with p = 0.040 (Table 4). In relation to canal location, the prevalence of adequate length was more than 79.5, 69.4, and 80.3% for the MB, ML, and distal canals, respectively. Chi-square test showed a significant difference between density, with p = 0.040 (Table 5). Finally, the overall acceptable RCF quality was over 60%, with no significant differences in the four evaluated parameters and characteristics.

DISCUSSION

Among the most significant roles of non-surgical root canal treatment is to eliminate primary bacteriological infection, prevent reinfection, and permit healing of periapical tissues. These measures can be achieved through endodontic treatments, retreatments, and sometimes, apical surgeries.³ This study was carried out to assess the quality of RCF of the mandibular first molar performed by endodontic consultants in the Asir region.

Even though the present study was limited to the Asir region with a small number of endodontists and small number of treated molars, the overall quality of the evaluated teeth that fulfilled the three criteria was between 63 and 70%. This range was not considered high, because endodontists frequently encounter challenging cases and patients with cooperation issues or teeth presenting anatomical difficulties, which may make them more inclined to seek treatment from endodontists. In addition, they consistently strive to reach the apex for improved preparation, resulting in the occurrence of overfilling among endodontists.²¹ Alley et al. (USA) reported that endodontists predominantly treat posterior teeth, and the survival rate of teeth treated by endodontists is significantly better than those treated by general practitioners.²³ Moreover, studies from Helsinki and India suggested that molars have a lower success rate than anterior teeth.^20,24 To enhance the RCF of molars and teeth with curved canals, endodontists must go through adequate training as there are always some difficulties in treating such cases. Those percentages are marginally in parallel with other percentages documented earlier from Saudi Arabia, Poland, and Turki.^17,21,22

Proximity of the RCF to the radiographic apex has been demonstrated to have a significant impact on the outcome of RCF.⁵ In the presence of apical periodontitis, roots filled close (0–2 mm) to the apex are associated with improved healing.³ Acceptable filling length was observed in 77% of all molars, which aligned with the 74.5% reported earlier in Poland.²¹ This ratio was lower than 82.3% reported by İnce Yusufoglu et al. in Turki but superior to 62.5% reported by Bajawi et al. (SA).^17,21 In other studies from Saudi Arabia, Helsinki, Yemen, the acceptable length of RCF of molars was lesser than that of the current study,^19,20,25 and this disparity could be related to the different qualifications of the operators. The results of the present work cannot be easily compared with the results of other studies because of differences in design, evaluation criteria, sample size, and type of study (clinical or preclinical).

Inadequate RCF with voids was the most affected by bacterial leakage. Therefore, apical periodontitis is associated with the residual microorganisms in the root canal.²⁶ Several regions of the root canal system, including ramifications, dentin tubules, and apical delta, are not accessed by endodontic instrumentation, irrigating chemical agents, and medications, allowing the presence of residual bacterial debris.²⁷ A homogeneous filling was found in 93% of root canals. This percentage was less than that reported from Poland (99.3%).²¹ By contrast, it was greater than that reported from Saudi Arabia (81.3%) and Turkey (62.7%).^17,21 Drukteinis et al. documented the quality and homogeneity of single-cone RCF, which revealed comparable findings between the GDP and endodontist groups in the apical and middle thirds, and the only significant differences were observed in the coronal third.²⁸ The current study showed that the acceptable density of the RCF was significantly associated with canal locations (p = 0.040), revealing that the distal canal was mostly associated with the presence on inadequate density, which was probably due to its large diameter.

Inadequate sealing of the obturation could supply nutrients for microorganism metabolism and growth through the infiltration of tissue fluid or saliva, consequently resulting in harm to periapical tissues.²⁷ The utilization of a rubber dam in RCF is connected to enhanced success rates, primarily due to the prevention of bacterial contamination of the root canal system originating from the oral cavity.²⁹ Additionally, employing a bioceramic sealer not only enhances the sealing but also contributes to achieving high clinical success rates in primary RCF and endodontic retreatment.^14,30 Given the physicochemical characteristics of hydraulic calcium silicate-based sealers, they can serve as fillers rather than just sealers, providing the clinician with the ability to augment the material’s volume within the root canal.³¹ Tapered gutta-percha points are employed to raise hydraulic pressure within the RCF, enhancing the distribution of the sealer. However, a recent systematic review showed that endodontic sealers do not influence the treatment outcome of permanent teeth with apical periodontitis.³² Bioceramic sealers have been reported to have a low incidence of postoperative pain,³³ but other studies demonstrated the opposite results.^34,35 Thus, this type of sealer was selected in the treatments of those cases.

In the present study, no associations were found between the RCF parameters and degree of qualification of the operator, location of the canal, and the side involved. By contrast, Pietrzycka et al. reported underfilling in the mesiobuccal canal of the first mandibular molars among Polish.²¹ In addition, Al-Anesi et al. revealed that inadequate length is frequent in distobuccal and mesiobuccal canals.²⁵ We did not record any significant differences between the right and left sides, except in terms of taper, which could be related to the chewing side of the involved participants and the use of brushing after eating. Marginally, similar percentages were recorded in the percentage of the persistence of radiographical abnormality associated with the apex of RCT teeth. This result was parallel to findings from previous studies carried out in Saudi Arabia that investigated this parameter.^36,37

Endodontists in this study used rotary NiTi instruments as part of their instrumentation technique. The advancement of NiTi rotary instruments into endodontic practices brought about a revolutionary change in the cleaning and shaping techniques applied to the root canal system.¹¹ NiTi rotary systems induce minimal canal transportation and working length (WL) alteration compared with stainless steel instruments, owing to their enhanced flexibility.^11,38 This technique enables faster and more precise root canal preparation compared with what can be achieved with stainless steel hand instruments. In their study, Arvaniti and Khabbaz noted negligible variance in root canal cleanliness when using different tapers (0.04, 0.06, and 0.08) for root canals prepared to a standardized apical size.³⁹ Consequently, all treated molars were prepared by taper (0.04) and filled by bioceramic and SC gutta-percha of the same taper. An association was found between taper of RCF and side involvement (p = 0.035), but no association was found in terms of operator experience and canal location.

The current cross-sectional radiographical study had some limitations. First, the sample size and the study area were small. Second, intraoral periapical radiographic analysis cannot replicate the exact quality of root canal obturation. This type of radiograph is a 2D image of a 3D object, so superimposition of anatomical structures may occur when radiographs were assessed.

CONCLUSION

The following conclusions were drawn from this cross-sectional radiographic study. The quality of RCFs was high in the density and taper parameters in all variables with particular needs for improvements in length. The overall quality was acceptable, which indicated that the delivered treatments by endodontists were performed according to the recommendations in the literature.

DECLARATION OF FIGURES’ AUTHENTICITY

All figures submitted have been created by the authors, who confirm that the images are original with no duplication and have not been previously published in whole or in part.

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