From lesion to resolution: A cone-beam computed tomography-based retrospective comparison of bioactive materials in nonsurgical root canal therapy

Abstract

Aim:

To evaluate periapical healing following nonsurgical root canal treatment of large periapical lesions using three bioactive materials, assessed using cone-beam computed tomography (CBCT) at 6 months and 1 year.

Materials and Methods:

A total of 40 teeth were taken for this retrospective study with single or multirooted teeth and periapical pathology of 4–8 mm in diameter, present with preoperative and follow-up CBCT scans available. All the cases considered underwent endodontic treatment using one of three bioactive materials (mineral trioxide aggregate, Biodentine, and bioceramics). Assessment of healing was done based on radiographic CBCT scans and CBCT–periapical index (PAI) criteria. The teeth were divided into healing, healed, or diseased based on the changes in the CBCT-PAI score after 6 months and 1 year. All the data were recorded in a tabular form and sent for statistical analysis using Chi-square test, t-test, and Friedman’s test.

Results:

While there was a statistically significant difference in individual teeth after 6 months (P = 0.01) and 1 year (P = 0.004), with maxillary incisors showing the highest percentage of healing after 1 year (29.6%), no significant difference was seen between the use of the three bioactive materials after 6 months (P = 0.97) or 1 year (P = 0.78), respectively. There was no statistically significant difference in age-wise (P = 0.27; 0.82) or gender-wise (P = 0.82; 0.39) distribution.

Conclusion:

Among all the teeth assessed, single-rooted maxillary teeth showed the highest amount of healing. All three bioactive materials showed a favorable outcome for the treatment regardless of the material used. In addition, healing outcomes were not significantly influenced by patient age or gender.

INTRODUCTION

The rationale for endodontic treatment is to eradicate the infection, to prevent microorganisms from infecting or reinfecting the root and/or periradicular tissues.[1] Most bacteria in the oral microbial flora possess the potential to infiltrate the root canal system both during and after pulp necrosis, thereby contributing to the initiation and progression of root canal infection that results in periapical inflammation.[2]

Periapical healing is a complex process involving interactions between osteoclasts and osteoblasts, resulting in bone replacement both structurally and functionally.[3] In the last decade, the introduction of modern microsurgical techniques, the use of magnification and enhanced illumination, and the availability of novel root-end filling materials have improved the reliability of apical surgery; a favorable outcome of more than 90% over 2 years had been reported.[4] Despite these advancements, surgical procedures do have their drawbacks; surgery affects the patient’s well-being, with swelling, pain, and discomfort being expected. Moreover, many anatomic locations and adjacent structures can affect the feasibility of periapical surgery due to inaccessibility or the risk of damaging adjacent anatomic structures.[5] However, in recent years, there is greater awareness of the root canal morphology, and the development of newer instruments, techniques, and materials has greatly enhanced the clinician’s abilities.[6] Therefore, nonsurgical root canal treatment has been suggested as the initial approach to treating large periapical lesions without surgical intervention.

Since its introduction in the 1980s, cone-beam computed tomography (CBCT) has become an important imaging modality in medicine and dentistry, enabling the detection of periapical pathologies even when conventional radiographs fail to show radiolucency.[7]

Bioactive materials were introduced to endodontics in the 1990s, first as retrograde filling materials and then as root repair cements, root canal sealers, and coatings for gutta-percha cones. These materials promote pulpal and periapical healing because of their biocompatibility and bioactive properties, thereby improving the prognosis for endodontic treatments.[8] Mineral trioxide aggregate (MTA), introduced by Torabinejad et al., is widely used in surgical and nonsurgical endodontics, but is limited by prolonged setting time and difficult handling. Biodentine, an MTA-based calcium silicate cement developed as a dentin substitute, and newer bioceramic materials offer improved handling and favorable biocompatibility, sealing ability, and physicochemical properties.[9,10]

Although all these three biomaterials have been used frequently in clinical practice, a comparison for all three in cases with large periapical lesion is yet to be done. Hence, the purpose of this study is to compare and evaluate the success rate of three bioactive materials in cases with large periapical lesions.

There is limited evidence from CBCT-based retrospective studies directly comparing the periapical healing outcomes of different bioactive materials following nonsurgical endodontic treatment. Large periapical lesions pose greater diagnostic and prognostic challenges and their nonsurgical management remains debated. Moreover, although MTA, Biodentine, and bioceramic materials are widely used in clinical practice, evidence directly comparing all three materials together using CBCT for large periapical lesions is limited, making such a comparison both clinically relevant and novel. A standardized, tooth-specific, and time-dependent evaluation is needed to determine whether material choice significantly influences healing when confounding clinical variables are controlled.

MATERIALS AND METHODS

Study design

This retrospective study was approved by the ethical committee of the institute (CDSRC/IEC/2024/37). The research was conducted between January 1, 2024, and December 31, 2024, and the trial was registered under CTRI with reg. no. CTRI/2025/10/096175CTRI/2025/10/096175.

Case selection

Case selection was based on the following inclusion criteria: patients between 20 and 60 years of age having no systemic diseases; fully formed mature teeth, teeth having periapical pathology of 4–8 mm in diameter; cases having preoperative and follow-up CBCT scans and teeth with appropriate hard tissue structure for it to be restored. Cases that were to be excluded were teeth in need of endodontic retreatment; teeth with fractures or perforations and endo-perio lesion.

Root canal treatment protocol

All endodontic procedures were performed under local anesthesia with 2% lignocaine with 1:80000 adrenaline and under rubber dam isolation. After access opening, biomechanical preparation was done using crown-down technique. Working length was taken using electronic apex locator, and preparation was done using a combination of Ni-Ti hand and rotary files, where most canals were prepared with 4% tapers, only anterior teeth as well as distal canals for mandibular molars and palatal canals for maxillary molars were prepared with 6% taper. 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid were used as irrigants, respectively, with sonic activation (EndoActivator) for 30 s, with the tip placed 2 mm above the apex. An interappointment medication with calcium hydroxide paste was placed and left for 1–2 weeks. Temporary restorations were placed at the end of each session.

Second visit

All the cases were divided into three groups based on the bioactive material used for obturation:

• Group 1: MTA

• Group 2: Biodentine

• Group 3: A bioceramic putty.

These materials were used as an apical plug, and gutta-percha was used to fill the rest of the canal. Obturation was checked using a postoperative radiograph, and postendodontic restoration was done using composite resin.

Follow-up

Following treatment, patients were scheduled for recall visits after every 6 months and 1 year until radiographic healing was evident. Information was entered into the patient’s follow-up form together with any signs, symptoms, or postoperative complications.

A total of 60 cases were selected, out of which 40 remained after follow-up, where the remaining excluded cases were majorly lost due to a lack of follow-up CBCT scans (n = 14), while a few were excluded due to unrestorable fracture/loss of tooth (n = 4) or recurrent swelling or sinus tract formation (n = 2).

Follow-up was standardized for inclusion, with a minimum follow-up of 12 months required, and outcome assessments were performed within predefined windows of 6 ± 2 months and 12 ± 3 months to account for variability inherent to retrospective data; CBCT–periapical index (PAI)-based radiographic healing served as the primary surrogate endpoint, supported by the absence of clinical signs or symptoms.

Healing assessment

In the study, healing assessments were based on clinical evaluation and radiographic CBCT scans and CBCT-PAI criteria.[11]

According to clinical and radiographic evaluations, the outcome was classified as follows:

1. Healed: There were no clinical signs or symptoms and no radiographically detected periradicular bone lesion (PAI score 1 or 2)

2. Healing: There were no clinical signs or symptoms, and the size of the radiographic bone lesion decreased (PAI value decreased, but it was still 2)

3. Diseased: The tooth was symptomatic and nonfunctional, with persistent or recurrent sinus tract, and/or the radiographic bone lesion was unchanged or enlarged (PAI score 3–5).

Lesion size was assessed on CBCT using the largest linear dimension (maximum diameter in any plane) at baseline and follow-up, and healing was standardized using CBCT-PAI scoring. All measurements were independently assessed by three different examiners blinded to the material used, and a minimum agreement of at least two examiners was required for the final recorded outcome to ensure measurement reliability.

Outcome assessment

Primary outcome

Periapical healing following nonsurgical root canal treatment assessed radiographically using CBCT and CBCT-PAI criteria at 6 months and 1 year.

Secondary outcome

• Comparative evaluation of periapical healing among three bioactive materials (MTA, Biodentine, and bioceramics) at 6 months and 1 year

• Influence of tooth type (individual teeth and arch location) on healing outcomes

• Association of patient-related variables, namely age and gender, with periapical healing success.

Success criteria

• Absence of any clinical sign (swelling and sinus tract) and/or symptom (spontaneous or provoked pain and tenderness to percussion/palpation) after 6-month and 1-year follow-up period

• Radiographically, a successful outcome was defined for cases showing a reduction in the volume of the lesion and categorized as healed or healing in CBCT-PAI assessment [Figure 1].

Figure 1.

Cone Beam Computed Tomography sections (a–b) Preoperative lesion (c-d) one year follow up with complete healing. (e–f) Pre-operative lesion and (g-h) reduction in size of the lesion over the 6 months follow up

Failure criteria

• Biological failure, involving presence of pain, swelling, sinus tract, etc., after the follow-up period

• Structural failure, involving fracture or removal of the restoration and/or the tooth.

Statistical analysis

Acquired data were recorded in tabular form and examined using SPSS 20.0 Windows Version (IBM, Armonk, USA). Given the relatively limited sample size inherent to the retrospective design, the statistical analysis was exploratory in nature and intended to identify trends and associations rather than establish definitive causal inferences. Chi-square test was used for comparison of demographic tables (age and Gender) and comparison of biomaterials, whereas Friedman’s test was done for intra-arch comparison. The analysis was done at 95% level confidence at P < 0.05 considered statistically significant.

RESULTS

The overall success rate was 90% at 6 months and 92.5% at 1 year, with a progressive shift from healing to healed status over time. No statistically significant differences were observed among the three bioactive materials at 6 months (P = 0.97) or 1 year (P = 0.78), nor across age (P = 0.27; 0.82) or gender groups (P = 0.82; 0.39). In contrast, tooth type showed a significant influence on healing at both 6 months (P = 0.01) and 1 year (P = 0.004); the detailed results are presented in Tables 1 and 2.

Table 1.

Combined healing assessment after 6 months

	Healing	Healed	Diseased	Total	P
Age
20–40	6	8	1	15	0.27
40–60	15	7	3	25
Gender
Male	9	8	2	19	0.82
Female	12	7	2	21
Tooth type
Maxillary incisors	4	4	1	9	0.01*
Maxillary canines	0	0	0	0
Maxillary premolars	2	2	0	4
Maxillary molars	3	2	0	5
Mandibular incisors	4	2	2	8
Mandibular canines	1	1	0	2
Mandibular premolars	4	2	0	6
Mandibular molars	3	2	1	6
Biomaterials
MTA	9	5	2	16	0.97
Biodentine	5	4	1	10
Bioceramics	7	6	1	14

* P<0.05=Statistically significant. MTA: Mineral trioxide aggregate

Table 2.

Combined healing assessment after 1 year

	Healing	Healed	Diseased	Total	P
Age
20–40	3	11	1	15	0.82
40–60	7	16	2	25
Gender
Male	3	14	2	19	0.39
Female	7	13	1	21
Tooth type
Maxillary incisors	1	8	0	9	0.004**
Maxillary canines	0	0	0	0
Maxillary premolars	1	3	0	4
Maxillary molars	2	3	0	5
Mandibular incisors	2	4	2	8
Mandibular canines	0	2	0	2
Mandibular premolars	2	4	0	6
Mandibular molars	2	3	1	6
Biomaterials
MTA	3	8	2	13	0.78
Biodentine	3	10	0	13
Bioceramics	4	9	1	14

* P<0.05=Statistically significant. MTA: Mineral trioxide aggregate

DISCUSSION

The present retrospective CBCT-based study evaluated the outcome of nonsurgical root canal treatment in teeth with large periapical lesions using three different bioactive materials. Although large periapical lesions have traditionally been associated with a reduced prognosis, growing evidence supports conservative endodontic management as a predictable and effective treatment option. In the present study, lesions >4 mm were included, in accordance with previous outcome-based studies that categorize lesions beyond this threshold as large, allowing meaningful comparison with existing literature.[12,13]

The overall success rate observed in this study was 90% at 6 months and 92.5% at 1 year, which is consistent with previously reported success rates for nonsurgical root canal therapy ranging between 70.9% and 90.9%.[14] The progressive increase in healed cases and reduction in diseased cases between the 6-month and 1-year follow-up periods highlight the time-dependent nature of periapical healing. These findings support the concept that radiographic healing often continues beyond early follow-up intervals and should be interpreted in conjunction with clinical findings.[15]

Successful periapical healing depends on effective elimination of intracanal infection and the creation of a favorable biological environment for tissue regeneration. The biocompatibility and sealing ability of the endodontic materials can have a significant effect on the treatment outcome.[16] Calcium silicate-based bioactive materials are used commonly due to their excellent sealing ability, biocompatibility, and potential to induce hard tissue formation, which is an advantageous property in periapical healing.[17] It forms calcium hydroxide that releases calcium ions for cell attachment and proliferation. It also encourages differentiation and migration of hard tissue-producing cells. In addition, the sustained release of Ca²⁺ and OH⁻ ions increase the local pH, creating an alkaline environment that is both antimicrobial and conducive to mineralized tissue formation. The interaction of these calcium ions with phosphate present in tissue fluids results in the rapid precipitation of hydroxyapatite on the surface of the material. The development of an apatite layer is initiated by the release of calcium ions from calcium-silicate particles along with the formation of Si–OH groups on the cement surface. This biologically active apatite coating enhances protein adsorption, leading to the formation of a protein-rich layer that facilitates osteoblast attachment.[18]

CBCT was used in this study for the assessment of periapical healing, as it provides superior diagnostic accuracy compared with conventional two-dimensional radiography. CBCT allows three-dimensional visualization of lesion size and bone changes, enabling more reliable detection of healing progression. Previous studies have demonstrated that the most substantial reduction in periapical lesion size occurs within the 1^st year following treatment, which supports the selected follow-up intervals of 6 months and 1 year in the present study.[19]

Despite these favorable biological properties, the present study found no statistically significant difference in healing outcomes among MTA, Biodentine, and bioceramic materials at either the 6-month or 1-year follow-up. This finding is in agreement with previous studies reporting comparable clinical outcomes among different calcium silicate-based materials, suggesting that their shared bioactivity and sealing ability may play a more important role than differences in material composition or handling characteristics.[20]

Patient-related factors such as age and gender did not significantly influence healing outcomes in this study. These findings are consistent with previous reports that found no significant association between demographic variables and the outcome of nonsurgical root canal treatment.[21,22,23] This suggests that biological healing following adequate endodontic therapy may be largely independent of age and gender within the adult population studied.

In contrast, tooth type had a significant influence on periapical healing, with single-rooted maxillary teeth, particularly maxillary incisors, demonstrating the highest percentage of healed cases. This observation is in agreement with previous studies reporting more favorable outcomes for anterior and single-rooted teeth compared with posterior and multirooted teeth.[24] This may be attributable to the complex anatomy of multirooted teeth, accessibility, and technical difficulties in treating them, as well as to heavy occlusal stresses acting on these teeth. In addition, the higher vascularity of maxillary bone compared with mandibular bone may further enhance healing potential.

The present study design inherently carries several limitations associated with its retrospective nature, which may have introduced heterogeneity and potential confounding factors. Variations in canal anatomy, lesion size within the defined range, operator skill, instrumentation techniques, irrigation protocols, and obturation approaches could not be fully standardized and may have influenced healing outcomes. In addition, differences in occlusal loading, quality of coronal restoration, and patient compliance with follow-up visits represent further confounding variables that could not be entirely controlled. To minimize these effects, strict inclusion and exclusion criteria were employed, limiting the sample to systemically healthy adults with mature teeth, comparable lesion sizes, and available preoperative and follow-up CBCT scans, thereby reducing biological and diagnostic variability.

Although the absence of a control group and the loss of cases due to unavailable follow-up CBCT scans may limit the generalizability of the results, the study design reflects real-world clinical practice and provides valuable comparative data on the performance of bioactive materials in nonsurgical management of large periapical lesions. Future prospective, randomized studies with standardized treatment protocols, larger sample sizes, and longer follow-up durations are recommended to further clarify the influence of individual materials and reduce the impact of confounding variables.

CONCLUSION

Within the limitations of this retrospective CBCT-based study, nonsurgical root canal treatment demonstrated favorable periapical healing in teeth with large periapical lesions at 6 months and 1 year follow-up. Comparative evaluation showed no significant difference in healing outcomes among MTA, Biodentine, and bioceramic materials, indicating similar clinical effectiveness. Periapical healing was influenced more by tooth-related factors than by patient age or gender, supporting the use of a conservative, nonsurgical approach and highlighting the need for future prospective studies with standardized protocols to further refine outcome prediction.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.