A Cross-Sectional Study of the Factors Affecting the Periapical Status of Endodontically Treated Teeth

Abstract

The objective of the study was to evaluate the relation of various clinical and radiographic factors on the periapical status of teeth treated endodontically by postgraduate students. Radiographic and clinical parameters related to root canal fillings, periodontal condition, coronal restorations, caries, endodontic signs and symptoms, and treatment-related complications were evaluated. Bivariate analysis and a multiple logistic regression model were used to analyze the data. In total, 157 endodontically treated teeth in 124 patients were investigated, 86 (54.8%) of which were molars. Radiographically, 136 (86.6%) teeth had periapical normality and 141 (90.5%) were asymptomatic. Only 20 (12.7%) of the root canal fillings were deficient, but 77 (49.1%) coronal restorations were inadequate. Thirty-six (22.9%) teeth had caries, whereas 60 (38.2%) had periodontal disease. Bivariate analysis showed that only the type of caries (p = 0.019) and ideal apical limit of the root canal filling (p = 0.03) were significantly related to the periapical status. However, multiple logistic regression analysis indicated no significant relationships between the periapical status and the parameters studied. In conclusion teeth treated endodontically by postgraduate students showed high-quality root canal fillings and periapical normality. Moreover, the presence of caries, inadequate coronal restorations, and periodontal disease were not related to periapical status of these teeth.

Keywords

Coronal restoration quality, Endodontic treatment, Periapical status, Root canal-filling quality.

Introduction

The prevalence of periapical lesions in endodontically treated teeth varies from 50% to 80% [1,2]. This high prevalence underlines a serious problem in dental public health and has economic, medical, and ethical repercussions, because such pathology can cause local and systemic complications [3,4].

Epidemiological studies of root canal fillings in different populations worldwide [1,3-10] have emphasized that their poor technical quality is associated with apical periodontitis [3-7,10,11]. Other investigations have also shown a relation between inadequate coronal restorations and high rates of apical periodontitis [5,6,10,12]. Given that coronal restorations protect the contiguous fillings from microleakage of fluids and oral microorganisms [2,12,13], restoration failure allows microbial microinfiltration [12,13] and facilitates root canal infection, in turn affecting periapical health [6,14]. Endodontically treated teeth are also susceptible to caries and periodontal disease, which would change their health status [15-17]. Some studies [3,18] showed a positive relation between extensive caries in endodontically treated teeth and increased incidence of apical periodontitis. Furthermore, pulpal infection is a risk factor for periodontitis, which can affect the repair of alveolar bone loss [17,19]. However, limited information is available on periodontal condition and other clinical parameters related to periapical status of endodontically treated teeth [15,17,20,21].

Thus, the purpose of this study was to evaluate the relation of various clinical and radiographic factors on the periapical status of teeth treated endodontically by postgraduate students.

Materials And Methods

This cross-sectional study was approved by the Human Research Ethics Committee of the Federal University of Jequitinhonha and Mucuri Valleys (UFVJM). Patients who had received endodontic treatment at the Clinic of Specialization in Endodontics, UFVJM, between 2002 and 2005 were contacted by either telephone or a home visit and invited to participate in the study. Data were collected through anamnesis and clinical and radiographic evaluations. The clinical evaluation was performed by an examiner with previously assessed expertise (SMCSS). Orthoradial periapical radiographs (Ultra-speed film, Eastman Kodak Co., Rochester, NY) were obtained by an experienced professor (JAS) using the bisecting-angle technique and manually processed using the temperature–time technique. Three different examiners with previously assessed expertise performed the radiographic evaluation.

The intraexaminer and interexaminer correlation values were 0.82–0.92 and 0.76–0.80, respectively, as determined by intraclass correlation coefficients. Disagreements were resolved by consensus.

Clinical and radiographic parameters

The following parameters were analyzed:

I) Age (classified into 4 age groups), gender, type of endodontically treated teeth (topographically classified into 4 groups), and presence of adjacent and opposing teeth to the endodontically treated teeth.

II) Endodontic signs and symptoms (induced or spontaneous painful sensitivity, sinus tract, edema, erythema, and exudation) and treatment-related complications (ledge, perforation, calcified root canal, broken instruments, and overfilling).

III) Coronal restoration

a) Type of material (permanent or temporary).

b) Extension (inlay, onlay, or full crown).

c) Number of involved surfaces (≤ 2 or >2 surfaces).

d) Clinical quality (adequate: intact permanent restoration, appropriate margins, and no fissure during probing; inadequate: permanent restoration with excess material, secondary caries, open margins or fractures, presence of temporary restoration, or no coronal restoration).

e) Radiographic quality (adequate: well-adapted restoration; inadequate: restoration with excess material in contiguous areas, open margins, or recurrent caries).

In the final classification of coronal restoration, clinical and radiographic parameters were simultaneously considered.

f) Intraradicular post (present or absent, length of remaining gutta-percha, and presence of a space between the filling material and the post).

IV) Root canal-filling quality: Three independent examiners assessed the quality of the root canal fillings by developing the periapical radiographs in the dark room, with a 6-fold increase on a millimeter grid. Apical limit, taper, and homogeneity were graded according to ideal or altered scores. The combination of these scores defined the quality of root canal fillings, as illustrated in Figure 1.

Figure 1: “Drawing of root filling quality standard as a function of radiographic parameters.”

V) Periapical status: The periapical status was assessed radiographically as follows3:

a) Normal (no change or the apical periodontal ligament space does not exceed twice the lateral periodontal ligament space).

b) Periapical lesion (periapical radiolucency exceeding at least twice the lateral periodontal ligament space).

VI) Caries: Teeth were classified according to the presence or absence of caries, type of caries (primary or secondary), degree of involvement of mineralized structures (enamel and dentin), presence or absence of cavitation, and activity (active or inactive).

VII) Periodontal condition: Four surfaces (vestibular, lingual/palatine, mesial, and distal) were examined. Altogether, 6 positions for the anterior teeth and premolars and 8 positions for the molars were evaluated and higher values or worse condition were considered at each location. The results were classified as follows:

a) Visible plaque(22) (absent: no visible plaque in every evaluated region; present: visible plaque in at least 1 position).

b) Bleeding on probing(1) (present: visible bleeding until 15 s after probing in at least 1 position; or absent).

c) Degree of mobility(15) (absent or present).

d) Furcation involvement(15) (absent or present).

e) Periodontal disease23 (present: tooth simultaneously presenting probing depth ≥ 4 mm and insertion loss ≥ 3 mm at 1 or more sites; absent).

In this study, the tooth was considered a sample unit. Therefore, for multirooted teeth, the periapical status and condition of the root canal with the worst root filling quality were evaluated. Endodontic treatment was deemed clinically successful if induced or spontaneous painful symptoms were absent and contiguous tissues were normal. Radiographic success was based on the normality of the apical periodontal ligament space. The combination of the clinical and radiographic evaluations determined the success or failure of the treatment.

Statistical Analysis

The data were initially analysed by a descriptive approach, using frequency distributions. Pearson's chi-square and Fisher's exact tests were used to identify the potential relations between the dependent variable (periapical status) and the independent variables. Then, multivariate forward logistic regression analysis was performed to verify the possible relations between these variables and the periapical status of the endodontically treated teeth. The level of significance was set at 5% (p < 0.05).

Results

The study included 124 patients (35 men and 86 women; age range, 19–65 years; mean 39.9 ± 11.5). In total, 157 endodontically treated teeth were evaluated, including anterior teeth (17.2%), premolars (28%), maxillary molars (26.1%), and mandibular molars (28.7%). Radiographically, 136 (86.6%) teeth had periapical normality; therefore, periapical lesions were infrequent (21 [13.4%] teeth; p = 0.001). About 20.0% of the teeth had some treatment-related complications.

The root canal-filling quality was significantly related to the type of endodontically treated teeth (p = 0.001): 63% of the anterior teeth had perfect root fillings, whereas 17.1% of the maxillary molars had deficient root fillings (p < 0.05). However, the quality of the root filling did not affect the periapical status (p = 0.858; Table 1). Further, the 3 filling quality-related parameters frequently had high ideal scores (p > 0.05), but only the ideal apical limit was significantly related to the periapical status (p = 0.03; Table 1).

Table 1: Influence of independent variables in the periapical status of endodontically treated teeth.

The coronal restoration-related parameters did not significantly alter the periapical status (p > 0.05; Table 2). Therefore, no relations were observed on quality of root canal filling/restoration with the periapical status (p > 0.05). With regard to caries, only the type of caries was significantly related to the periapical status (p = 0.01; Table 3). Periodontal disease was diagnosed in 38.2% of the endodontically treated teeth; however, no periodontal condition-related parameters were significantly related to the periapical status (p > 0.05).

Table 2: Association between clinical and radiographic findings of the coronal restoration and respective periapical status.

Table 3: Association between periodontal parameters and caries and respective periapical status.

Discussion

In the present study, contrary to other investigations [1,2,7,10], low prevalence of periapical lesions (13.4%), deficient root canal fillings (12.7%), and symptomatic teeth (9.5%) were observed. Furthermore, 44% of the root canal fillings had ideal scores in all the quality-related parameters, and 44.3% had altered scores only one parameter; therefore, 88.3% of these fillings presented high technical quality. The prevalence of periapical normality (~86.6%) was similar to that in other studies carried out in similar settings with standardized clinical protocols [11,21-24]. The prevalence of treatment-related complications was 20%, which could be explained by the fact that approximately 55% of the endodontic treatments were performed in molars, whose complex root canal anatomy would be technically challenging for the operator [2,24]. These results have been largely attributable to the skill of postgraduate students. Endodontic treatment performed by specialists is generally assumed to be of better quality and more successful than that performed by general practitioners or graduate students [5,24]. Nevertheless, Kereks and Tronstrad18 showed high-quality root canal fillings in treatments performed by students who followed standardized clinical protocols.

With regard to the parameters influencing the technical quality of the root canal fillings, 93.6% of the teeth had the ideal homogeneity, 77.7% had the ideal taper, and 59.8% had the ideal apical limit. However, bivariate analysis showed that only the ideal apical limit was significantly related to the periapical status, confirming previous outcomes [2,21].

Corroborating the findings of Kirkevang et al. [23] and Ørstavik et al. [25], no significant relation was observed between the periapical status and the root canal-filling quality or type of teeth. Similarly, Sidaravicius et al. [10] found that the quality of the root filling has little impact on the periapical status of endodontically treated teeth, except for cases of overfillings. Moreover, Chen et al. [3] showed that properly root-filled teeth have a similar rate of periapical lesions to those with deficient root fillings.

Analysis of the parameters related to coronal restorations revealed that 49.1% of the restorations were clinically and radiographically inadequate, and among these, 33.7% were absent. However, none of these parameters was significantly related to the periapical status of the teeth, as previously reported [3,5,6,17]. Conversely, other studies showed a significant effect of the coronal restoration quality on periapical normality [10,12,18]. In the present study, only 4 (15.4%) teeth without coronal restorations had periapical lesions, confirming the results found in previous investigations [10,26]. With regard to the presence of intraradicular posts or space between the posts and the filling material, no significant differences were found in the periapical status of the teeth. Eventually, this space might have developed in most of the teeth (80.4%), which had remaining gutta-percha with satisfactory length (>4 mm) [20,27,28].

In addition, the quality of the coronal restorations had no relation with the periapical status of the teeth, again confirming previous findings [29,30]. Siqueira Jr et al. [14] observed that the coronal restoration quality affected the periapical status of inadequately root-filled teeth or those without restorations. However, a significant prevalence of periapical lesions has also been observed in adequately root-filled teeth. Considering this, coronal restoration-related parameters have almost no relation with the presence of periapical lesions in adequately root-filled teeth. In vitro studies have shown bacterial microleakage in root canal fillings when the coronal seal is inadequate [13,20]. However, for the development of a pathological periapical process, it would be necessary to consider the interaction between the amount of microorganisms, their virulence capacities, and the immunological defense mechanisms of the patient [26].

Periodontal and periapical lesions have similar microbiota and pathophysiology, in addition to the communication links between the periodontium and the endodontium. Therefore, cross-infection between these environments might occur [17]. In this study, approximately 40% of the endodontically treated teeth had periodontal disease. However, similar to previous observations [21,25], none of the periodontal condition-related parameters was related to the periapical status. On the other hand, Chen et al. [3] and Stassen et al. [17] showed that the presence of apical periodontitis dictates the severity of horizontal bone loss and periodontal attachment.

In this study, primary caries were significantly related to the periapical status of the endodontically treated teeth, confirming the results of Kirkevang, et al. [23]. Although the teeth radiographically presented high-quality root canal fillings, microorganisms in the carious lesions might have infiltrated the root canal system to reach the periapex and cause lesions [3]. In a recent study, teeth with caries extending to the pulp chamber presented a high incidence of periapical lesions [3]. Although caries and periodontal disease represent the foci of infection in dental tissues, the lack of a relation between periodontal disease and the periapical status, when compared with caries, could be explained by the protective effect of the immune system in inhibiting the entry of periodontal microorganisms and their toxins into the periapex. However, multivariate logistic regression analysis showed that the periapical status of the teeth studied did not relate with any of the investigated clinical and radiographic parameters.

Conclusion

The teeth treated endodontically by postgraduate students had high-quality root canal fillings and periapical normality. The clinical and radiographic factors such as caries, coronal restorations, and periodontal condition showed slight or no relation with the periapical status of these teeth..

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