Evaluation of technical quality and periapical health of root-filled teeth by using cone-beam CT

Abstract

Objective

This study aimed to assess the quality of root fillings, coronal restorations, complications of all root-filled teeth and their association with apical periodontitis (AP) detected by cone-beam computed tomography (CBCT) images from an adult Turkish subpopulation.

Material and Methods

The sample for this study consisted of 242 patients (aging from 15 to 72 years) with 522 endodontically treated teeth that were assessed for technical quality of the root canal filling and periapical status of the teeth. Additionally, the apical status of each root-filled tooth was assessed according to the gender, dental arch, tooth type and age classification, undetected canals, instrument fracture, root fracture, apical resorption, apical lesion, furcation lesion and type and quality of the coronal structure. Statistical analysis was performed using percentages and chi-square test.

Results

The success rate of the root canal treatment was of 54.4%. The success rates of adequate and inadequate root canal treatment were not significantly different (p>0.05). Apical periodontitis was found in 228 (45.6%) teeth treated for root canals. Higher prevalence of AP was found in patients aging from 20 to 29 years [64 (27%) teeth] and in anterior (canines and incisors) teeth [97 (41%) teeth].

Conclusions

The technical quality of root canal filling performed by dental practitioners in a Turkish subpopulation was consistent with a high prevalence of AP. The probable reasons for this failure are multifactorial, and there may be a need for improved undergraduate education and postgraduate courses to improve the clinical skills of dental practitioners in endodontics.

INTRODUCTION

The quality of root canal fillings is associated with the adequate treatment of roots, which depends on their length in relation to the apex, homogeneity and quality and type of coronal restorations ^{23 , 29} . The successful interpretation of endodontic problems was associated with diagnostic imaging techniques that provide information about the teeth and their surrounding anatomy.

Numerous studies have used periapical radiographs to assess the anatomic structure of teeth and to analyze the number and location of root canals ^{23 , 29} . However, periapical radiographs provide two-dimensional images, therefore, they cannot provide adequate information about the root canal configuration. Recently, cone-beam computed tomography (CBCT) is being widely used in dental practice and research. CBCT have been used to provide greater details about the root canal anatomy and their surrounding structures compared to radiographic images ¹⁹ .

Follow-up studies on root canal treatment in educational hospitals, which have showed that the reality for the overall population might be somewhat different, present success rates between 35%-96% ^{14 , 20 , 21} . A root canal treatment applied with the highest standards of care can heal the periapical lesion ¹² . However, regardless of the population group and geographic location, studies confirm that outcomes of root canal treatments performed by general dental practitioners show much lower success rates ^{4 , 23 , 27 , 30} . One of the most important reasons for such poor quality treatment is an increase in the prevalence of apical periodontitis (AP).

The chronic inflammation of the periapical structure usually develops itself without the patient experiencing symptoms, thus, radiological examination is still fundamental for its detection. AP is generally underestimated and sometimes not detectable in panoramic and periapical radiographic images, because of the superposition of anatomical landmarks ⁶ . The main advantage of a 3D view of maxillofacial structures is that they have no superimpositions with anatomical landmarks ¹⁵ .

Previous studies assessed the quality of root canal fillings by radiography ^{23 , 29} . However, no studies have yet assessed the quality of root canal fillings using CBCT in a Turkish subpopulation. This study was aimed to assess the quality and periapical status of root canal fillings by CBCT in a Turkish subpopulation.

MATERIAL AND METHODS

CBCT images of root canal fillings were obtained from patients who first visited the Faculty of Dentistry of Dicle University, Diyarbakir, Turkey, between 2009 and 2011. We assessed a database of 522 CBCT scans of endodontically treated teeth obtained from 276 patients according to sex and age (15-72 years), and records of third molars were excluded. This study was based on a retrospective assessment of CBCT images and approved by the Medical Ethics Committee of Şifa University (Protocol #33-2013).

The selection criteria included the following:

1. Patients over 14 years old;

2. Patients visiting the clinic for the first time;

3. CBCT images of good quality;

4. Previous root canal treatment performed by general practitioners.

Exclusion criteria included the following:

1. CBCT images presenting deformations;

2. Unsatisfactory coronal restoration;

3. Recently traumatized and treated teeth;

4. Orthodontic patients.

The CBCT images were obtained using a CBCT scanner (I-CAT Vision TM Imaging Science International, Hatfield, USA, 2008) at 120 kVp, 18.54 mA, with an exposure time of 8-9 s. The voxel size of the images was 0.3 mm. The acquisition process was performed by an experienced radiologist according to the recommendations of the manufacturer, with the minimum exposure necessary for adequate image quality. Intraexaminer calibration of the CBCT images was first performed to evaluate the reliability of the assessment. All images were assessed separately two times by two examiners (an endodontist and a maxillofacial radiologist) with a 2-week interval between the assessments. In the case of disagreements between the pair, these were discussed with another radiologist until a consensus was reached. The following factors were assessed in all images: sex, dental arch, tooth type and age classification, undetected canals, instrument fracture, root fracture, apical resorption, apical lesion, furcation lesion, type and quality of the coronal structure and sufficient (overfilled) and insufficient (underfilled) root canal filling (RF) (Figure 1). The criteria used for the examination were slightly modified from those described by De Moor, et al. ⁴ (2000): sufficient RF was defined as a root canal space that was completely filled, ending 1–2 mm from the apex, and with no voids; insufficient RF was defined as a root canal space that was poorly condensed, ending more than 2 mm from the apex, and with voids. Additionally, the quality of coronal restoration was assessed according to any permanent restoration, radiographic signs of recurrent caries, open margins or presence of temporary coronal restorations or no restoration (Figure 2).

Figure 1. A-E) Insufficient (underfilled) root canal filling; B) undetected canals; C,G) Apical lesion; F) Overfilled root filling and instrument fracture I); Apical resorption H,J); Sufficient root filling.

Figure 2. Parameters recorded on endodontically treated teeth with cone-beam computed tomography (CBCT).

Statistical analysis

The CBCT images used to assess the technical quality of root canal fillings were analyzed using the chi-square test (p<0.05).

RESULTS

In this study, a total of 522 teeth obtained from 276 patients (134 females and 142 males), aging from 15 to 72 years, were assessed. Of these teeth, 265 (50.8%) were from females, and 257 (49.2%) were from males; the difference between genders was statistically significant (p<0.05). With regard to age, patients under 20 and over 60 years presented lower prevalence of endodontic treatment (Table 2).

Table 1 lists the types and prevalence of root-filled teeth. There were 370 (70.9%) maxillary teeth and 152 (29.1%) mandibular teeth. Incisors and canines (𝑛=232) were treated most frequently, followed by premolars (𝑛=166) and molars (𝑛=124). The periapical status of all root-treated teeth is presented in Table 1. Of all the endodontically treated teeth, 54.3% showed a healthy periapical structure, whereas 45.7% showed the presence of AP lesions in dental arches, and the difference was not statistically significant (p>0.05). The distribution frequency of the AP affected the maxillae [168 teeth (45.4%)] and mandible [70 teeth (46%)] in the dental arch was similar. There were found 238 (45%) AP lesions. The AP lesions were located most frequently in maxillary incisors and canines [80 (15.3%) teeth], followed by maxillary premolars [50 (9.6%) teeth] and maxillary molars [38 (7.3%) teeth]. The AP lesions were located less frequently in mandibular incisors and canines [17 (3.3%) teeth]. In addition, without considering the technical quality of root canal treatments, the prevalence of apical health and coronal structure of the teeth showed no statistically significant difference (p>0.05). An assessment of the coronal structure of the teeth with root canal fillings revealed that 61.9% had coronal restorations, whereas 38.1% had been crowned. The relationship between the periapical status and type and quality of coronal structure was not statistically significant (p>0.05); the distribution is presented in Table 1.

Table 1. The outcome of 522 endodontically treated teeth as determined cone-beam computed tomography (CBCT).

	Total	Apical periodontitis	Periapical status Healthy	Chi-square P values
	n %	n %	n %
Sex
Female (n:134)	265 50.8%	103 38.9%	162 61.1%	0.01
Male (n:142)	257 49.2%	135 52.5%	122 47.5%
Dental arch
Maxilla	370 70.9%	168 45.4%	202 54.6%	0.484
Mandible	152 29.1%	70 46%	82 54%
Tooth type
Incisors+Canines	232 44.5%	97 40.5%	135 47.5%	Maxilla:0.04
Premolars	166 32%	71 30%	95 33.5%	Mandible:0.29
Molars	124 23.5%	70 29.5%	54 19%
Age classification
14-20	44 8.4%	12 27.3%	32 72.7%	0.016
20-30	119 22.8%	64 53.8%	55 46.2%
30-40	107 20.5%	52 48.6%	55 51.4%
40-50	117 22.4%	47 40.2%	70 59.8%
50-60	109 20.9%	47 43.1%	62 56.9%
60 and ↑	26 5%	16 61.5%	10 38.5%
Undetected canals	44 8.4%	30 68.2%	14 31.8%	0.002
Filling length
Underfilled	152 29.1%	113 74.3%	39 25.7%	0.000
Adequate	323 61.9%	80 24.8%	243 75.2%
Overfilled	47 9%	45 95.7%	2 4.3%
Instrument fracture	1 0.2%	1 100%	-	0.456
Root fracture	2 0.4%	1 50%	1 50%	0.704
Apical resorption	77 14.8%	69 89.6%	8 10.4%	0.000
Apical lesion	76 14.6%	74 97.4%	2 2.6 %	0.000
Furcation lesion	1 0.2%	1 100%	-	0.456
Type and quality of coronal structure
Restoration	323 61.9%	156 65.5 %	167 58.8%	0.06
Crowned	199 38.1%	82 34.5%	117 41.2%

Of 522 teeth, 199 (38.1%) had inadequate length of filling, being short of the radiographic apex or overfilled, whereas only 323 (61.9%) had ideal filling length. The prevalence of AP was 113 (74.3%) in underfilled teeth, and 45 teeth (95.7%) had been overfilled with gutta-percha or sealer material. Overall, a root canal filling was considered as an adequate filling length with periapical healing in only 243 (75.2%) of all ideal filling length, whereas AP was recorded in 80 teeth (24.8%). In the present study, the complications of all root-filled teeth were assessed. One (0.02%) had broken instruments inside the canals, 44 (8.4%) had undetected root canals, 2 (0.4%) had root fractures, 77 (14.8%) showed apical resorption, 76 (14.6%) had apical lesions, and 1 (0.2%) had furcation lesions.

DISCUSSION

This study is the first to assess the periapical status of root-filled teeth using CBCT images of a Turkish subpopulation. The negative factor of this study is that the data analyzed are restricted to available information and thus may suffer from preconception ²⁴ . However, the most important advantage of this method is the comprehensive sample size ⁸ . Previous studies typically used conventional panoramic ¹⁷ or full-mouth periapical radiographs ^{8 , 23 , 29} . The main disadvantage of conventional radiographs is that they only provide static information about a dynamic process and it is impossible to estimate whether a periapical lesion is increasing or decreasing in size ²³ . Recently, CBCT has been widely used in endodontic therapy ⁵ . The most important advantage of CBCT in endodontics is that it allows a better visualization of the details of the root canal anatomy than radiographic images and provides a 3D view for diagnosing and managing endodontic complications ^{5 , 19} , therefore, we used CBCT images in this study. In our study, endodontic treatment was more prevalent in patients aging between 20 and 30 (22.8%) and between 40 and 50 (22.4%) years, and these results lead to tooth loss with advancing age. Furthermore, patients aging over 60 years presented lower prevalence of endodontic treatment than those under 60 years in this study, because this population probably have extracted teeth - especially molar teeth.

In previous studies of root-filled teeth in a Turkish subpopulation, 40.5-74% of root fillings were reported to be inadequate; many of these were undertaken in general practice or hospital settings ^{7 , 8 , 10 , 22 , 23} . Kayahan, et al. ¹⁰ (2008) assessed 1268 teeth from 280 panoramic radiographs and found apical lesions in 40.5% (514) of the teeth. Sunay, et al. ²² (2007) assessed panoramic radiographs of 375 patients and found pathological findings in 53.5% of the teeth. In this study, 238 (45.6%) teeth showed periapical lesions, and the other 284 (54.4%) showed a healthy periapical structure.

The present study targets a population from a rural area and parallel results regarding the prevalence of periapical lesions presented in other studies of a Turkish subpopulation ^{7 , 10 , 22 , 29} . The relation between this study and these results lies in the fact that the income and treatment opportunities for patients, particularly those living in the rural areas of Turkey, are limited. Finally, the extraction of teeth due to low socioeconomic status leads to a limited epidemiological increase in the number of root-filled teeth.

However, Fernandes, et al. ¹⁵ (2013) evaluated a total of 5585 teeth of 300 Brazilian patients assessed by CBCT images and found periapical lesions in only 192 teeth (3.4%). Peak, et al. ¹⁶ (2001) evaluated the treatment outcome of a total of 406 teeth with root canal fillings done by military general dentists in the Royal British Army and found periapical lesions in 62 (15%) teeth. On the other hand, in a Taiwanese population, Chueh, et al. ² (2003) assessed a total of 1085 teeth and found that the rate of root canals with adequate fillings were 61.7%. While unacceptable fillings due to inadequate root fillings were of 25.0% and overfilling were of 12.6%, 0.6% had no fillings in their root canals. Similarly, in a Senegalese subpopulation, only 17.7% of the root fillings were technically acceptable ²⁷ . In the Kosovan population, Kamberi, et al. ⁹ (2011) found that, following endodontic procedures by general dentists, 30.5% of the root filled teeth were technically acceptable.

Unlike the results of the studies mentioned above, Tarim, et al. ²³ (2013) assessed 1448 roots of 831 teeth obtained from 484 patients. They found that 73.4% of these showed periapical lesions and the other 26.6% showed a healthy periapical structure. In another study ⁷ , the panoramic and periapical radiographs of 400 patients were investigated and the root canal treatment was applied to 890 teeth, and the presence of periapical lesions could be found in 658 (73.9%) teeth.

In our study, we found that 45.5% (238) of the teeth showed periapical lesions. This can be explained by the fact that the survey population did not represent the entire country; there were differences in healthcare services and socioeconomic factors; and the age of the assessed patients, sample of patients, and assessment methods differed from each other.

In addition, a common problem in endodontics is the limitation of conventional radiographic images, where the anatomical structures may be confused with periapical pathosis, and the number of canals in root canal treatment might often be unclear ¹⁹ . Furthermore, internal, external, buccal or lingual lesions could not be identified by conventional radiography when compared with CBCT ¹³ .

The correct diagnosis of complications such as perforations, resorptions, undetected canals and root fracture can be challenging and may result in an unsuitable treatment ^{7 , 19} . Therefore, the assessment of such complications is particularly important in endodontics. These problems may be overcome using the CBCT technique that provides a 3D view for diagnosing and managing endodontic complications ³ .

The results of this study agree with those of other studies that found the quality of root canal treatment to be an important factor for prognosis of the coronal restorations. Different studies have disputed the effects of coronal restorations and quality of root canal treatment on periradicular tissues ^{8 , 11 , 18 , 28} . Most studies recognized that a relationship exists between the type of restoration and the periradicular health. They concluded that the quality of the root canal filling was much more important than the type of restoration ^{8 , 23} . Kayahan, et al. ¹⁰ (2008) reported that healthy periradicular tissues were significantly higher in teeth with optimal root canal fillings in any type of restoration. Furthermore, Tronstad, et al. ²⁸ (2000) demonstrated that the quality of a well-sealed coronal restoration influenced the outcome significantly positively when combined with optimal root canal treatment. In the present study, root filled teeth restored with or without crowns showed no statistically significant differences in the occurrence of periapical pathology (p>0.05), but teeth without crowns showed more AP than crowned teeth.

In the literature, many epidemiological studies have shown that there is a high prevalence of periapical disease in the root filled teeth with poor technical quality ^{1 , 22 , 23} . It is because bacteria can remain within the root canal system in filled teeth, and their products may cause reinfection of the root canal system in a relatively short time ^{25 , 26} . The results from the present study confirm the findings of other studies that afirmed that inadequate root filling teeth present higher AP prevalence (74.3% underfilled and 95.7% overfilled, p=0.00). Adequate root canal fillings were found in 323 (61.9%) of all examined samples, 24.8% of these teeth were recorded with presence of AP.

Finally, it is clear that the quality of the root canal fillings is associated with higher professional standards and a better technique, undergraduate and postgraduate training and better equipment. Furthermore, we believe that an adequate coronal restoration and root canal treatment were important to the overall success of the root canal treatment.

CONCLUSION

The technical quality of root canal filling performed by dental practitioners in a Turkish subpopulation was consistent with a high prevalence of AP. The present study, despite its limitations, confirmed the findings of other studies. The probable reasons for treatment failure are multifactorial and may indicate the need for improved undergraduate education and postgraduate courses to improve the clinical skills of dental practitioners in endodontics. There is a need to standardize the assessment of the quality of root canal fillings, therefore, this study provides useful information about general dental conditions in a Turkish subpopulation, which can help in describing new strategies for the treatment and protection of periradicular tissues. Additionally, this study contributes toward future applications of CBCT images in cross-sectional studies.