A retrospective three-dimensional assessment of the prevalence of apical periodontitis and quality of root canal treatment in Mid-West Indian population.

INTRODUCTION: This study aims to report a retrospective observation of the prevalence of apical periodontitis (AP) and quality of root canal treatment in cone-beam computed tomography (CBCT) scans among the Mid-West Indian population.
MATERIALS AND METHODS: A total of 1229 CBCT scans were obtained across different CBCT centers in western India. After the exclusion criteria, those that were included were divided into broadly two groups - those that were filled and those that were unfilled. Various parameters were taken into account such as AP, length of the root canal filled, and coronal filling.
RESULTS: There were a significantly higher percentage of nonfilled canals. Poor filling quality, inadequate coronal restoration, and also missed extra canal were significantly associated with AP. Both males and females showed higher presence of AP in the nonfilled teeth than filled ones (X2 - Chi square value M = 612.156, P < 0.00001, X2 F = 1032.9092, P < 0.00001).
CONCLUSION: (1) The inadequacy of the filling of the root length was a contributory factor to the higher prevalence of AP among the study population. (2) The density of the filling and the quality of the coronal filling also significantly affected the successful outcome of the root canal treatment. Copyright:

INTRODUCTION

Apical periodontitis (AP) is an acute or chronic inflammatory disease occurring in the periodontal tissues mostly by microorganisms from the infected root canal.[12] In nontreated teeth, AP represents a defensive response to infection, however, in post endodontic treated teeth, the presence of AP is either due to reinfection of the root canal system due to inadequate cleaning, obturation, or inadequate coronal seal that allows the bacterial penetration, extrusion of irrigant, medicaments, sealer, and obturating material into the periapical tissue.[2]

An ideal clinical and radiographic scenario should be healing and absence of disease (AP); clinical and radiologic criteria are commonly used to access the status of endodontic treatment, but morphologic variations, bone density, and angulations of radiographs can impact radiographic interpretations.[3] The role of periapical radiographs is indispensable, as it provides evidence of the presence, absence, and persistence of AP,[3] but these are the two-dimensional depictions of three-dimensional structure and the limitations are well entrenched.[4] Cone-beam computed tomography (CBCT) is an advanced technology that is widely applied in various fields of dentistry. It provides three-dimensional (3D) imaging of maxillofacial structures without superimposition of the anatomical landmarks. Studies have reported high accuracy of CBCT in the assessment of AP.[5] Various studies have suggested that the improvement of the quality of root canal treatment is essential to improve the health of the periapical status. One study reports a direct relation of good postendodontic restorations to success rate (80 vs. 75.7%), and poor restorations resulted in significantly more failed cases when compared with poor endodontics (30.2 vs. 48.6%).[67] Unfortunately, a high percentage of randomized controlled trials (RCTs) chiefly performed by general practitioners have been reported in many surveys, i.e., 24.5%–65.8% of the endodontically treated teeth presented with AP.[891011] Very few studies have been reported out among the Indian population regarding root canal filling and periapical status. We report the retrospective observation of CBCT scan reports of the same among the population across Mid-West India.

MATERIALS AND METHODS

Study population

The sample consisted of 1229 CBCT scans of patients reported to the two CBCT centers (3D Accuitomo and Orthophos XG 3D, Sirona, Germany, voxel size 0.5 mm) across the mid-west of India. All the scans were taken between November 16, 2019, and August 16, 2020. A gap of 3 months from March to May was taken for the study, as there was lockdown due to the coronavirus pandemic. All the CBCTs were taken for diagnostic purposes such as implant planning, orthognathic surgery, and endodontic evaluation. No patient underwent CBCT scans exclusively for this study. The study was approved by the ethical committee of the institute (MCES/EC/604-A/2019).

Inclusion criteria were as follows: (1) patients between 25 and 45 years of age, (2) permanent teeth, and (3) good quality scans.

Exclusion criteria were as follows: (1) maxillary and mandibular third molar, (2) distorted and blur scans, and (3) scans with deciduous teeth (pls exclude scans with no teeth). After exclusion criteria were employed, 1016 scans with a total of 26,669 permanent teeth were present.

Radiographic assessment

CBCT scans were evaluated using Orthophos XG 3D (Sirona, GmbH, Germany). The scans were evaluated using Galileo's software version (1.9.2) in sagittal and axial sections at the coronal middle and apical portion on a 30” monitor with a resolution of 2660 × 1600 pixels (Dell 3008WFP, Dell Inc.). For every patient, the information was recorded on a customized Excel form: (i) name, (ii) age, (iii) gender, (iv) number and location of root canal-filled teeth with AP, (v) number and location of root-filled teeth without AP, and (vi) the number of unfilled teeth with AP. The total teeth were categorized into two groups: Endodontically treated and nontreated teeth. In endodontically treated teeth, the following parameters were assessed:

Apical periodontitis

AP is radiolucency in connection with the apical part of the root, exceeding at least two times the width of the lateral part of the periodontal ligament

Multirooted teeth were classified according to the root exhibiting the most severe periapical condition.

Root-filled teeth

A tooth with a radiopaque material in the pulp chamber and/or root canals was considered root filled or endodontically treated

An adequate root filling was defined as a root filling contained within the tooth, terminating no more than 2 mm from the radiographic apex and without visible voids

A root filling more than 2 mm short of the radiographic apex, containing voids or extruded beyond the apical foramen, was considered an inadequate root filling

Multirooted teeth were categorized by the root with the most inadequate root filling.

Coronal restoration

Coronal restoration (CR) was defined as a restoration of the coronal part of the tooth

Crowns or partial restorations such as inlays and onlays were considered indirect restorations

The quality of the restoration was also assessed radiographically and classified inadequate if the restorations were absent or if recurrent caries, open margins, or overhangs were detectable

In addition, the presence or absence of posts was noted.

Missed canals

All the scans specific to the teeth were evaluated for missed canals considering the incidence of extra canals.

The descriptions of parameters are listed in Table 1.

Table 1

Description of parameters assessed in the study

Parameters	Score
Apical periodontitis	0 - Intact periapical bone structures
Estrela et al., 2008,[3] cone-beam computed tomography periapical index	1 - Diameter of periapical radiolucency 0.5-1 mm
	2 - Diameter of periapical radiolucency 1-2 mm
	3 - Diameter of periapical radiolucency 2-4 mm
	4 - Diameter of periapical radiolucency 4-8 mm
	5 - Diameter of periapical radiolucency 8 mm score (n) #E*Expansion of periapical cortical bone score (n) #D*Destruction of periapical cortical bone
Length of root canal filling (Moor et al., 2000[12])	Adequate (root canal filling terminating 0-2 mm from the radiographic apex)
	Inadequate (root cabal filling terminating >2 mm from radiographic apex)
	Overfilled (root canal filling extending beyond apex)
	Pulpotomy (root filling limited to pulp chamber)
Technical quality of root filling (European Society of Endodontology 2006[28])	1 Adequate (no voids or defects along the walls of canal, filling terminating between 0-2 mm from radiographic apex)
	2 Inadequate (voids or defects along the walls of canal, filling ending more than 2 mm short of radiographic apex)
Density of root canal filling (Dugas et al., 2003[13]) see some other criteria	1 Adequate (uniform density and adaptation of the filling along the root canal walls)
	2 Inadequate (visible space laterally and voids along the root canal walls)
Coronal restoration (Siqueira et al., 2005[14]) extra canals	1 Adequate (radiographically intact restoration with no signs of leakage)
	2 Inadequate (radiographic signs of overhang restoration, open margin, secondary caries, and fractured restoration)
	1 Filled extra canals (MB2, P2, radix, MM, etc.)
	2 Unfilled extra canals

All the observations were done by two different and experienced radiologists.

Statistical methods

The data were tabulated and statistical analysis was carried out using SPSS, Chicago, USA, 22.0 using Chi-square test. P < 0.05 was considered statistically significant.

RESULTS

A total of 1016 scans with 26,669 permanent teeth were included in the final reporting of this retrospective study. Table 2 shows the distribution of the teeth as per the periapical status.

Table 2

Distribution of cone-beam computed tomography examined teeth according to periapical status P=0.00001

Periapical status	Root-filled teeth	Nonfilled teeth	Total
With apical periodontitis	215 (35.0)	399 (65.0)	614
Without apical periodontitis	243 (0.1)	26,012 (99.9)	26,055
Total	458	26,411	26,669

Chi-square value - 4141.224, df=1. There were significantly higher percentage of non-filled teeth and a teeth without apical periodontitis

We observed that there was a significantly higher percentage of an inadequately filled canal associated with AP. Furthermore, a greater amount of overextended fillings were seen compared to adequate filled canals. A higher percentage of the inadequate density of filling was observed with positive cases of AP. Thus, a statistically significant percentage of adequately filled canals were associated with no AP. Poor filling quality, inadequate CR, and also missed extra canal were significantly associated with AP. Table 3 shows the distribution of various parameters across the different teeth. Table 4 shows the relationship between parameters recorded on CBCT and the type of teeth. Table 5 shows the gender-wise distribution of the presence or absence of AP.

Table 3

Relationship between parameters recorded in root-filled teeth

Parameters	Score	Apical periodontitis		χ2, df, P
		Present	Absent
Length of root filling	1=Adequate	42	212	189.583, 3, 0.0000
	2=Inadequate	114	27
	3=Overextended	48	12
	4=Pulpotomy	3	0
Density of root filling	1=Adequate	27	178	185.0, 1, 0.000
	2=Inadequate	195	58
Technical quality of root filling	1=Adequate	5	182	1960, 1, 0.000
	2=Inadequate	222	49
Quality of coronal restoration	1=Adequate	23	242	144.0, 1, 0.000
	2=Inadequate	186	7
Frequency of missed extra canals	1=Missed extra canals	167	24	189.0, 1, 0.000
	2=Treated extra canals	18	49

Table 4

Relationship between parameters recorded on cone-beam computed tomography and the type of teeth

Parameters	Score	Incisors	Premolars	Molars
Length of root filling	1=Adequate	60	82	98
	2=Inadequate	8	20	119
	3=Overextended	12	13	39
	4=Pulpotomy	0	0	7
Density of root filling	1=Adequate	42	87	119
	2=Inadequate	39	48	123
Technical quality of root filling	1=Adequate	42	62	64
	2=Inadequate	39	58	193
Quality of coronal restoration	1=Adequate	41	73	151
	2=Inadequate	26	58	109
Frequency of missed extra canals	1=Missed extra canals	53	21	117
	2=Treated extra canals	58	89	120

Table 5

The gender-wise distribution of the presence or absence of apical periodontitis

Apical periodontitis	Male		Female		Total
	Filled teeth	Nonfilled teeth	Filled teeth	Nonfilled teeth
Present	59	267	108	435	869
Absent	97	9752	194	15,957	26,000
Total	156	10,019	302	16,392	26,869

Gender-wise distribution of the presence or absence of apical periodontitis is seen in this table. Both males and females showed significantly less prevalence of apical periodontitis in the non-filled teeth than the filled ones Males (x2 =612.156) P<0.00001. Females (x2= 103.9092)

DISCUSSION

To predict the future needs for dental treatment in a growing population, it is important to assess the endodontic and periodontal status of teeth, so as to evaluate the need for improvement or additional expertisation. The quality of root canal preparation, obturation, and coronal seal are essential factors to achieve high success rates even in infected canals. Retrospective studies have demonstrated a high prevalence of AP in many western countries. Prevalence of 20%–60% is commonly reported by German, Dutch Suleiman, Turkish, and other populations.[101115] However, most studies originate from the Scandinavian and European populations. Although the frequency of root-filled teeth and technical quality of the treatment varied among these epidemiological studies, they revealed an association between the quality of root fillings and the periapical status, and this emphasized that improvement in the quality of root fillings is required to promote periapical health.

The variation in these parameters could originate from the different study populations, types of teeth, different age groups, and periods for the data collection. The prevalence of AP and root canal-filled teeth has been studied across the world; however, studies in the Indian population are scarce. Some studies have used periapical radiograph for evaluation of AP[1617] while others used panoramic radiograph[1218] and yet others used a combination of both periapical and panoramic images.[1319] An intraoral radiograph gives a two-dimensional image for three-dimensional structure. Estrela et al., in their review of epidemiological studies, viewed the limits of periapical and panoramic radiography.[3] Wu et al., in the function of the limitation of previous systematic reviews evaluating the root canal outcome, considered the need of re-evaluating the outcome of longitudinal studies using CBCT.[20]

CBCT provides multiplanar images in submillimeter resolution; moreover, the greater sensitivity of CBCT scans will aid in the precise assessment of the periapical region and improve the reliability of prevalence studies on AP.[2122] According to Patel et al., 2019,[3] CBCT provides additional information which improves diagnostic accuracy in decision-making and treatment planning. The previous studies which were based on CBCT images had a small sample size.[21] The current study included scans from 1016 patients. A recognized limitation of cross-sectional studies is the impossibility to determine whether an AP lesion is healing or expanding. Petersson et al.[23] found that after a 10-year period, the number of healed periapical lesions was equal to the number of newly developed lesions, indicating that the results of cross-sectional studies remain meaningful.

The prevalence of AP was higher than the previously reported epidemiological studies by Chala et al.[2] and Tavares et al.[24] In the present study, we observed that inadequate or overfilling of the canal was strongly associated with the AP similar to the results of Sunay et al.[11] We also observed that there was lesser AP associated with nonendodontically filled canals, similar to the reports by Van der Vekeen et al.[22] In the present study, the prevalence of AP in endodontically treated teeth was 35%, which is less than the studies reported from Scotland (51%),[23] Canada (51%),[13] Denmark (52%),[10] Turkey (53%),[11] Spain (65.8%),[8] and Germany (61%).[25] The discrepancies observed between the results of different studies might be explained by the following aspects: (i) lack of an equal proportion of the populations being compared, (ii) lack of standardization of the methods of radiographic assessment, (iii) use of teeth or individuals as referential, (iv) quality of endodontic treatment rated by either general dentists or endodontists, and (v) different levels of endodontic practice and infection control in the different populations as stated by Khullar et al.[7] We also observed that there was an apparent increase in AP with an increase in the tendency to miss an extra canal. Gender wise, there was an increased AP observed regarding both filled and nonfilled teeth among the females compared to the males. This probably could be because of more number of female samples in our study. Although there is no specific literature to support gender-based failure cases of RCTs, further observations on this parameter could add to interesting insights.

There were significantly fewer filled teeth than unfilled ones, which could be due to lack of awareness, affordability, and neglect among the Indian population. This was in contrast to the reports by Van der Vekeen et al., where a higher percentage of filled canals were present in the study.[22] Furthermore, the same study reported 54.5% of the inadequately filled canal, whereas we observed 55.24% of teeth to be inadequately filled. Kirkevang et al.[10] observed that the success of the root canal also depended upon the coronal filling, and not only on the adequacy of the apical seal,[11] but Siqueira et al.[14] report that this may not always be essential. The observations by Van der Vekeen et al.[22] provide no significant association between these parameters, which is in contrast to our findings, where significant association was observed between the poor quality of coronal filling and AP.[22] An Indian study reported that AP was present in approximately 37% of the teeth which had adequate CRs compared to 83% of the teeth which did not have adequate CRs. Furthermore, the mixture of adequate CR and adequate root filling resulted in a significantly reduced incidence of AP (21.6%) compared to the presence of AP (97%) when both parameters scored as inadequate. AP was four times more likely to be presented in unacceptable RCTs, and three times more likely in inappropriate CR compared with the appropriate ones, which was very much higher than the observations of our study.[7]

Artifacts such as metallic objects may hinder the observation of CBCT images and hence it is difficult to assess the coronal restorations. A combination of clinical and radiographic diagnostic tests would be useful.[326]

Gender-wise no significant difference was present in terms of apical periodontitis in this study. These results are inconsistent with other studies reported in the literature.[13] Siqueira et al. found that the quality of the CR was significantly less important than the quality of the root filling.[14] Hommez et al., 2002,[27] found both quality of root filling and CR to be equally important. The results of the present study revealed the significant impact of the CR on AP when the root filling was adequate. Study protocols evaluating the quality of CRs concerning the prevalence of AP should combine both clinical and radiographic examinations. It seems reasonable to emphasize that, in the interest of the patient, both CR and root canal treatment should be of the best possible quality.

The study has certain limitations:

We cannot generalize this finding to entire India, since no specific random sampling was followed. Subjecting the patients to CBCT simply for the sake of the study was not considered to be an ethical approach by the authors

More detailed distribution of the patients across other parameters such as age and sex was essential. However, previous studies also have not reported much of any significant gender and age predilection of AP and endodontically treated teeth

This study can serve as a planning guideline in a teaching institute set up well equipped with CBCT.

CONCLUSION

We conclude the following from our observation:

The inadequacy of the filling of the root length was a contributory factor to the higher prevalence of AP among the study population

The density of the filling and the quality of the coronal filling also significantly affected the successful outcome of the RCT

Missed canals gave rise to higher AP

Untreated or unfilled teeth showed significantly lesser AP than the endodontically filled teeth.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.