Success of maintaining apical patency in teeth with periapical lesion: a randomized clinical study

Success of maintaining apical patency in teeth with periapical lesion: a randomized clinical study

MENA Dental Science

2. January 2020

Hakan Arslan, Ezgi Doğanay Yıldız, Hüseyin Sinan Topçuoğlu, Ebru Tepecik, Nilay Ayaz

Objective: The aim of this study was to evaluate the effect of maintaining apical patency on periapical healing and postoperative pain levels in teeth with necrotic pulp and apical periodontitis. Method and materials: Fifty mature teeth with periapical lesions were randomly distributed into two treatment groups: patency, and nonpatency (n = 25). Patients were followed up over a 12-month period using clinical and radiographic assessments. The data were statistically analyzed using independent-samples t test and chi-square tests at a 95% confidence level (P = .05). Results: Seventeen teeth in the patency group (85.0%) and 19 teeth in the nonpatency group (86.4%) were classified as being successfully treated (P = .900). Conclusions: Within the limitations of the present study, maintaining apical patency did not affect endodontic treatment outcomes. (Quintessence Int 2019;50:​–0; doi: 10.3290/j.qi.a43047)

Introduction

Cleaning and shaping of the root canal system is one of the most important steps in root canal treatment.1 During the shaping of the root canals, some procedural errors such as blockage, transportation, ledges, and perforations can occur.2 Adequate debridement of the root canals, especially in the apical portion, can help decrease these kinds of procedural errors.3 However, the elimination of organic tissue and dentinal debris reduction is difficult, especially in the apical region, since the complexity of the root canal system increases in this region.3 Maintaining apical patency during instrumentation has been used for the prevention of the accumulation of debris and soft tissue in the apical third of root canals, thereby decreasing the possibility of procedural errors such as blockage, transportation, ledges, and perforations.4,5

Apical patency is defined as a technique that allows for debris elimination in the apical portion of the canal by recapitulation with a small file through the apical foramen.6 A patency file should be a small and flexible, and used by moving it passively through the terminus of the root canal without binding or enlarging the apical constricture.2 A size 10 K-file has been reported to be the most popular size of patency file.4 The patency file is set at 1 mm longer than the final working length.2

Delivering irrigation solutions to the apical region of the root canal in sufficient amounts is also extremely important because, in this complex area (ramifications, deltas, and fins), microorganisms can survive by colonizing organic tissue and dentin or by obtaining nutrients from the periradicular tissue and releasing byproducts associated with the development of apical periodontitis.7,8 Maintaining apical patency improves the delivery of irrigants into the apical third of the canal9 and also leads to minimizing the presence of gas bubbles that can impede irrigation solutions from reaching the apical third.10

The use of this technique is controversial because of the possibility of deleterious effects such as debris extrusion and injury to periapical tissues.2,11 The risk of postoperative pain has been shown to be higher in case of direct mechanical trauma caused by instruments, and by the apical extrusion of infected debris.12 However, in a recent systematic review of randomized controlled trials, it was reported that maintaining apical patency did not increase postoperative pain levels.13

The success of endodontic therapy depends on various factors such as age, gender, and the quality of coronal restoration and canal filling.14 In the last few decades, advances in technology, along with procedural improvements, have changed endodontic therapy. However, it has been shown that these improvements do not obviously affect the success of endodontic therapy.15 Therefore, there is still a need for studies to increase the success of endodontic therapy. One of these methods is apical patency. The literature includes studies evaluating the effect of apical patency on postoperative pain and some in vitro studies.4,5,13 However, there is no published research assessing the effect of periapical lesion healing when apical patency was maintained in relation to when it was not. Thus, the aim of the present study was to evaluate the effect of maintaining apical patency on periapical healing, and also postoperative pain levels in teeth with necrotic pulp and apical periodontitis. The null hypothesis was that there would be no significant difference between patency and nonpatency groups in terms of periapical healing and postoperative pain.

Method and materials

Ethical approval for this study was provided by the Research Ethics Committee (20 December 2016, no. 72/16). The study was also registered to the Clinical Trials Registry (no. TCTR20161230003).

Study specimens were recruited from the pool of patients referred to the Department of Endodontics for root canal treatment. According to the clinical and radiologic examinations, only patients aged 18 to 65 years who had maxillary or mandibular single rooted teeth with pulp necrosis and radiographic evidence of apical periodontitis (with periapical index score 3 or 4),16 without severe preoperative pain levels (visual analog scale [VAS] < 50), were included. Pulp necrosis was confirmed by a negative response to a cold pulp test and was confirmed later by the absence of bleeding on opening the pulp chamber. Exclusion criteria were pregnant females, patients with generalized chronic periodontitis, teeth with previous root canal treatment, periodontal pockets larger than 3 mm, systemic disorders, severe preoperative pain level (VAS > 50), severe preoperative percussion sensitivity (VAS > 50), preoperative palpation sensitivity, presence of a sinus tract, treatment with antibiotics in the past month, and analgesic treatment within the past 5 days.

Randomization and blinding

Fifty subjects were enrolled in the study. Patients were randomly assigned to one of two groups using a web program (available at www.randomizer.org): patency and nonpatency. Patients were blinded and not informed of the allocation. Since the nature of the interventions was not appropriate, the practitioner could not be blinded. 

Clinical procedures

All endodontic treatments were performed in a single-visit approach, and a standardized treatment protocol was used for all. The standard treatment protocol was as follows: after each patient signed the informed consent forms, s/he was given local anesthesia (1.8 mL of 4% articaine with 1:100,000 epinephrine) (Ultracaine DS forte, Aventis). Rubber dam isolation was used, and an access cavity was prepared in all cases. 

For the nonpatency group, determination of the working length was made using an apex locator (Raypex 6, VDW). The working length was also confirmed with an intraoral periapical radiograph. In the nonpatency group, all instruments were used up to the working length. During the procedure, 2 mL 2.5% sodium hypochlorite was used after each instrumentation cycle for irrigation of the root canal. 

For the patency group, determination of the working length was made using an apex locator (VDW) and confirmed by an intraoral periapical radiograph. A size 10 K-file was used as a patency file, by being moved passively through the terminus of the root canal (1 mm longer than the working length) without enlarging the apical foramen, to maintain patency between each instrument and before each irrigation sequence. This procedure was performed to improve the efficiency of irrigants in the apical third, to prevent the accumulation of debris and soft tissue in the apical third of the root canal, and to prevent procedural errors. 

For root canal preparation, FlexMaster File System (VDW) was used. The handpiece was used with an endodontic motor (XSmart Plus, Dentsply Maillefer). After preparation, for the final rinse, the canals were irrigated with 5 mL 2.5% NaOCl followed by 5 mL 10% citric acid for 1 minute. The root canals were dried using sterile absorbent points, and then the canals were filled using lateral condensation technique and 2Seal sealer (VDW). The final restoration was performed with dentinal adhesive and composite resin (Filtek P60, 3M Dental Products). 

Clinical assessment

Patients were informed that they might experience pain in the days following treatment. If patients experienced unbearable pain, they were instructed to use 400 mg ibuprofen (Brufen, Abbott). They were instructed to record their pain experience at 1, 3, 5, and 7 days after the treatment on a 10-cm VAS, and the details of analgesic intake on a customized form. At reevaluation visits (at 1 week and 3, 6, 9, and 12 months), pain levels, percussion and palpation sensitivity, swelling, and the presence of sinus tract were recorded. Pain levels (spontaneous pain and percussion) were also recorded.

Radiographic assessment

Standardized, periapical radiographs were taken for each tooth prior to root canal treatment, after root canal treatment, and at the 3-, 6-, 9-, and 12-month reevaluation visits. For standardization of periapical radiographs, a sensor holder (Super-Bite, Kerr) was used. Periapical radiographs were taken using the Belmont Phot-X II (Takara-Belmont) with phosphor plates (VistaScan II, Dürr Dental). According to the radiograph, which was taken just after the root canal treatment, the quality of root canal treatment (vertically [normal, short, or over] and horizontally [with voids or without voids]) was noted. 

Two operators evaluated the periapical radiographs in order to assess the periapical lesions. A standardized protocol was used among the operators with a scoring system described by Ørstavik et al.16 The periapical radiographs were evaluated twice by each operator, with 15 days between each evaluation. The scores for the periapical lesions were as follows:17,18

Absence of a periapical lesion: if the postoperative radiographic periodontal ligament space was no wider than 0.5 mm

Reduction of the periapical lesion: if the decrease in the size of radiographic lesion was 20% or more

Enlargement of the periapical lesion: if the increase in the size of radiographic lesion was 20% or more

Uncertain: if the case cannot be defined as absence, reduction, or enlargement of the periapical lesion.

Assessment of success of the treatment 

Only cases with both periapical lesion scores of 1 or 2 and clinically asymptomatic (without sinus tract, swelling, with no spontaneous palpation or percussion pain) were recorded as successful. Cases with periapical lesion scores of 3 or 4, or a symptomatic tooth were recorded as unsuccessful.

Statistical analysis

All statistical analyses were performed at a 95% confidence level (P = .05) by an examiner who was blinded to the assignment of the groups and the outcome. The statistical analyses were performed using SPSS version 20 software (IBM). Intra-examiner reproducibility was performed, and the inter-examiner agreement was analyzed using Kappa test. The data with regard to pain level and pain on percussion were statistically analyzed with independent-samples t test. The other data were analyzed using chi-square tests. 

Results

Out of 50 patients, 42 (20 teeth for the patency and 22 teeth for the nonpatency groups) successfully attended the follow-up clinical and radiographic assessment (Fig 1). One tooth was extracted because of nonrestorable fracture of the restorative material. 

Figure 1

CONSORT flow diagram.

 

There were no significant differences in terms of demographic data (age, P = .746; sex, P = .491) between the groups (Table 1). 

Patient distribution to the groups according to the demographic data

Parameter Patency (n) Nonpatency (n) P value
Patients 20 22 NA
Age (y) < 35 9 11 0.746
≥ 35 11 11
Gender Male 7 10 0.491
Female 13 12
Tooth type Maxillary central incisor 2 4 0.173
Maxillary lateral incisor 8 5
Maxillary canine 0 3
Mandibular central incisor 6 4
Mandibular lateral incisor 1 2
Mandibular canine 0 3
Mandibular premolar 3 1
Initial periapical lesion score Score 3 7 5 0.379

Success

Based on clinical and radiographic examinations (Fig 2 and Table 2), the treatment 17 teeth in the patency group (85.0%) and 19 teeth in the nonpatency (86.4%) were classified as being successful (P = .900). There was no significant difference between the males and females in terms of the outcome of the root canal treatment success (P = .700). 

Effect of gender, age, tooth type, root canal filling, and maintaining apical patency on the success of the treatment

Parameter Successful (n) Unsuccessful (n) P value
Gender Male 15 2 0.7
Female 21 4
Age (y) < 35 20 0 0.012
≥ 35 16 6
Tooth type Maxillary central incisor 6 0 0.301
Maxillary lateral incisor 11 2
Maxillary canine 3 0
Mandibular central incisor 9 1
Mandibular lateral incisor 2 1
Mandibular canine 3 0
Mandibular premolar 2 2
Root canal filling vertical Normal 31 5 0.498
Short 3 0
Over 2 1
Root canal filling horizontal Sufficient (without voids) 34 4 0.032
Insufficient (with voids) 2 2
Maintaining apical patency Patency 17 3 0.9
Nonpatency 19 3

Successful treatment outcomes were affected by age according to the results of the present study. Out of 20 teeth on patients less than 35 years old, the treatment of 20 was successful (100.0%), while in the case of the treatment of 22 teeth on patients at least 35 years old, 16 were successful (72.7%). Mandibular lateral incisors (66.7%) and mandibular premolars (50.0%) had the lowest rates of treatment success. Maxillary central incisors and maxillary/mandibular canines had the high rates of success (all 100.0%). Horizontal sufficiency of the root canal filling was a predictor of the success rate (P = .032). Horizontally sufficient root canal fillings (89.5%) had higher rates of success than insufficient ones (50.0%). However, the success rate was not affected by the vertical limit of the root canal filling (normal, short, or over) (P = .498) (Table 2).

Pain

There were no significant differences between groups in terms of the pre- (P = .810) and postoperative pain level (P = .412), preoperative pain level on percussion (P = .173), and postoperative pain level on percussion (P = not applicable) (Table 3).

Effect of gender, age, tooth type, root canal filling, and maintaining apical patency on the success of the treatment

Preoperative and postoperative pain (visual analog scale) of the patients and number of patients who needed analgesics according to the group

Parameter Patency Nonpatency P value
Preoperative pain (mean ± SD) 3.75 ± 7.81 4.55 ± 12.70 0.81
Preoperative percussion pain (mean ± SD) 7.50 ± 14.08 2.73 ± 7.51 0.173
Postoperative percussion pain (mean ± SD) 0.00 ± 0.00 0.00 ± 0.00 NA
Pain at day 1 (mean ± SD) 2.85 ± 8.51 5.77 ± 11.25 0.352
Pain at day 3 (mean ± SD) 3.25 ± 8.17 3.45 ± 6.87 0.93
Pain at day 7 (mean ± SD) 1.65 ± 7.37 0.32 ± 1.49 0.412
Patients who needed analgesics postoperatively (n) 1 1 0.945
NA, not applicable; SD, standard deviation.

Discussion

To the best of the present authors’ knowledge, this is the first study on the effect of maintaining apical patency on periapical healing in teeth with necrotic pulp and apical periodontitis. In both groups, the percentage of success rate was high and similar (85.0% for the patency group and 86.4% for the nonpatency group). However, there was no significant difference among groups. In addition, there was no significant difference among groups in terms of postoperative pain. Therefore, the null hypothesis could not be rejected.

This study was designed as a randomized controlled two-armed clinical trial. By using a randomization program (available at www.randomizer.org), the subjects were randomly divided into two groups. Thus, the best evidence was provided (level 1 evidence). The degree of standardization was another strength of the present study. Only single-rooted teeth with periapical lesions were included in the study. The treatment protocols were also standardized. Those allowed as much standardization as possible and limited bias. 

Although it has been stated that maintaining apical patency during instrumentation decreases the possibility of procedural errors,4,5 improves the delivery of irrigants into the apical third of the canal,9 and helps remove the bacterial biofilm that is present around the apical foramen,19 it did not affect endodontic treatment outcomes in the present prospective clinical study. This could be due to a variety of reasons, including the complexity of root canals, microbial factors (structure and the presence of external biofilm), root fillings, the sample size used in the study, and the fact that improved cleaning does not result in a better outcome.18

The majority of the study population was female (59.5%). However, there was no significant difference between the male and female groups in terms of the outcomes of the root canal treatment (P = .700). This finding is in accordance with those of previous reports on this topic.20,21

In the present study, all of the patients who had failure in root canal treatment were older than 35 years of age. Thus, the cutoff was set at 35 years. Successful treatment outcomes were affected by age according to the results of the present study. Out of the treatment of 20 teeth on patients less than 35 years old, 20 were successful (100.0%), and in the case of treatment of 22 teeth on patients at least 35 years old, 16 were successful (72.7%). This finding is in accordance with one previous report,22 but not in accordance with another.20 The difference between the studies can be explained by the presence or absence of periapical lesions. In the present study, teeth with periapical lesions were included.

In total, mandibular lateral incisors (66.7%) and mandibular premolars (50.0%) had the lowest rates of treatment success. Maxillary central incisors and maxillary/mandibular canines had the high rates of success (100.0%, 100.0%, and 100.0%, respectively). Also, maxillary lateral incisors (84.6%) and mandibular central incisors (90.0%) had a high but not 100.0% success rate. The failures in the case of mandibular incisors and premolars may be associated with their complex anatomy,23-25 and in maxillary lateral teeth with the curvature at the apical third.26 Although the numbers for assessment of success in terms of tooth type are very low, it can be stated that maxillary lateral incisors and mandibular incisors/premolars require special attention. 

According to the results of the present study, horizontal sufficiency of the root canal filling was a predictor of success rate. Horizontally sufficient root canal fillings (89.5%) had higher rates of success than insufficient ones (50.0%). However, the success rate was not affected by the vertical limit of the root canal filling (normal, short, or over). This finding was not in accordance with those of previous studies.20,27 The different results between the studies can be explained by the sample size. 

In a study evaluating the radiographic success of endodontic treatment and periapical status, Kielbassa et al14 reported that the percentage of periapical pathosis increased for higher age groups, women’s periradicular health was better than that of men, and inadequate lengths or nonhomogenous obturations increased the apical pathosis. The results of the present study are in accordance with the study by Kielbassa et al14 in terms of age and the horizontal sufficiency of root canal filling, but not in terms of gender and the vertical sufficiency of root canal filling. The different results between the studies can be explained by the different methodologies used in the studies.14

There are many studies related to the effect of maintaining apical patency on postoperative pain levels after root canal treatment, with different results of these studies. Although some authors have concluded that there is no significant effect of maintaining apical patency on postoperative pain levels,28,29 others have concluded that maintaining apical patency is associated with lower postoperative pain levels when compared with nonpatency groups.30,31 A recent systematic review of randomized controlled trials reported that maintaining apical patency does not increase postoperative pain levels in teeth with vital/nonvital pulp.13 This result is in accordance with the results of the present study. 

Conclusion

According to this prospective outcome study of root canal treated teeth with periapical lesions, it can be concluded that maintaining apical patency during instrumentation does not affect endodontic outcomes. The success of the endodontic treatment is affected by the age of the patient, horizontally insufficient root canal filling, and tooth type. 

Declaration

The authors deny any conflicts of interest related to this study. 

 

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Hakan Arslan
Hakan Arslan
Associate Professor Dr

Department of Endodontics, Health Sciences University, Üsküdar, İstanbul, 34688, Turkey.

Ezgi Doğanay Yıldız
Assistant Professor

Department of End- odontics, Faculty of Dentistry, Kırıkkale University, Kırıkkale, Turkey

Hüseyin Sinan Topçuoğlu
Associate Professor

Department of Endodontics, Faculty of Dentistry, Erciyes University, Kayseri, Turkey

Ebru Tepecik

Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey

Nilay Ayaz

Department of Endodontics, Faculty of Dentistry, Ataturk University, Erzurum, Turkey