Clinical and Radiographic Evaluation of Indirect Pulp Capping with Mineral Trioxide Aggregate and Calcium Hydroxide in Primary Molars: A Systematic Review and Meta-analysis

Abstract

Aims and background

An optimal pulp capping material should promote the formation of reparative dentin, preserve pulpal vitality, and create an effective barrier against bacterial infiltration. Due to issues like disintegration and tunnel defects, mineral trioxide aggregate (MTA) has become a preferred recent alternative to calcium hydroxide (Ca(OH)₂) for indirect pulp capping in primary teeth. In the literature, there have been conflicting opinions regarding the selection of materials for indirect pulp capping. Hence, the aim of this systematic review was to evaluate and compare the effectiveness of MTA and Ca(OH)₂ as indirect pulp capping agents in deep carious lesions of primary molars.

Methods

This review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The databases searched included MEDLINE (via PubMed), Google Scholar, and Cochrane. Randomized clinical trials published until January 31, 2024, without year restrictions, were included. The systematic review assessed the effectiveness of MTA and Ca(OH)₂ as indirect pulp capping agents in primary molars.

Results

The search resulted in 412 published studies. Four hundred and five articles that did not meet the inclusion criteria, were duplicates, or were not in English were excluded. A total of seven studies were included in the systematic review to assess clinical and radiographic effectiveness, and five studies were selected for meta-analysis (radiographic effectiveness). MTA showed greater reparative dentin formation as compared to the Ca(OH)₂ group with a standardized mean difference of 0.45; however, the difference between the two groups was not statistically significant.

Conclusion

Both MTA and Ca(OH)₂ can be effectively utilized as indirect pulp capping agents in deep carious lesions of primary molars.

Clinical significance

This systematic review and meta-analysis highlights the effectiveness of MTA and calcium hydroxide [Ca(OH)₂] as indirect pulp capping agents in primary molars with deep carious lesions, providing valuable evidence-based guidance for pediatric dentists in selecting the most suitable pulp capping agent.

How to cite this article

CK A, Ninawe NS, Sawant S, et al. Clinical and Radiographic Evaluation of Indirect Pulp Capping with Mineral Trioxide Aggregate and Calcium Hydroxide in Primary Molars: A Systematic Review and Meta-analysis. Int J Clin Pediatr Dent 2025;18(8):1031–1038.

Introduction

Dental caries is widely recognized as a major oral health issue among children and stands as one of the most common chronic conditions impacting pediatric populations.¹ Preserving primary teeth is of utmost importance as they serve as indicators of the overall health of pediatric patients.² Moreover, treating deep carious lesions that are nearing the healthy pulp has perpetually presented a significant challenge in dental care.³ When there are no clear clinical signs or symptoms indicating pulpal involvement, indirect pulp capping (IPC) or indirect pulp treatment (IPT) may be considered as suitable approaches for managing deep carious lesions.⁴ Indirect pulp treatment employs a minimally invasive strategy focused on preserving the inner layer of carious dentin, which constitutes a vital tissue containing intact collagen capable of undergoing remineralization.⁵

Numerous materials have been employed as indirect pulp capping (IPC) agents for treating vital teeth with deep carious lesions. Additionally, calcium hydroxide, established as a gold standard for pulp capping, has been utilized since its initial description by Zander in 1939.⁶ It facilitates the development of reparative dentin by stimulating cellular differentiation, promoting extracellular matrix secretion, and facilitating subsequent mineralization.⁷ Furthermore, an ideal pulp capping agent should have the following qualities: the capacity to promote the production of reparative dentin, maintain pulp vitality, eliminate bacteria, ensure sterility and radiopacity, and provide an efficient bacterial seal. However, other agents are being preferred over calcium hydroxide for indirect pulp capping in deciduous teeth because of disadvantages such as disintegration and the formation of tunnel defects.⁸ Additionally, the gradual disintegration of calcium hydroxide after the development of a hard tissue barrier may create pathways for microorganisms, potentially resulting in calcific bridge defects that contribute to pulpal degeneration, dystrophic calcifications, and ultimately, pulpal necrosis.⁹

Therefore, mineral trioxide aggregate (MTA) represents a relatively recent addition to the choices of pulp-capping agents. MTA facilitates the formation of hard tissue by capturing growth factors and cytokines present within the surrounding dentin matrix. Remarkably, MTA exhibits superior marginal adaptation to dentin when compared to calcium hydroxide (CH). Over time, both MTA and CH result in the formation of thicker tertiary dentin; however, the completeness and thickness of the dentin barrier do not consistently correlate with clinical success. The primary determinant of clinical success lies in the sustained preservation of vitality of the pulp without any observable clinical signs or symptoms. Therefore, the selection of the pulp-capping material plays a crucial role in maintaining pulp vitality. Nevertheless, uncertainty persists regarding the comparative clinical and radiographic efficacy of MTA and CH as agents for pulp capping in primary teeth.¹⁰

Hence, the aim of the present systematic review was to assess clinical and radiographic outcomes of indirect pulp capping with mineral trioxide aggregate versus calcium hydroxide in primary molars.

Methods

Protocol and Registration

This systematic review followed the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (http:/www.prisma-statement.org). The protocol of the study was registered with PROSPERO (International Prospective Register of Systematic Reviews) with registration no.: CRD42023442068.

Search Strategy

The search process was performed independently by three examiners. The electronic databases MEDLINE (via PubMed), Cochrane, and Google Scholar were searched for articles published until January 31, 2024, without year restriction but only in English language. For each database, the following terms were combined: MTA, mineral trioxide aggregate, calcium hydroxide, Ca(OH)₂, indirect pulp capping, indirect pulp therapy, IPT. Boolean operators “AND” and “OR” were utilized to merge the search terms and formulate the overall search strategy. The specific strategies employed for each database are outlined in Table 1.

Table 1:

Search strategy in the database

Database	Search strategy	Findings
PubMed	#1 (((((MTA[Title/Abstract]) OR (Mineral trioxide aggregate[Title/Abstract])) OR (White MTA[Title/Abstract])) OR (Grey MTA[Title/Abstract])) OR (WMTA[Title/Abstract])) OR (GMTA[Title/Abstract]) #2 (((((Calcium hydroxide[Title/Abstract]) OR (Dycal[Title/Abstract])) OR (Ca(OH)2[Title/Abstract])) OR (CH[Title/Abstract])) OR (Calcium Hydroxide Cement[Title/Abstract])) OR (CHC[Title/Abstract]) #3 (((((Indirect pulp capping[Title/Abstract]) OR (IPC[Title/Abstract])) OR (Indirect pulp treatment[Title/Abstract])) OR (IPT[Title/Abstract])) OR (Dental cavity liners[Title/Abstract])) OR (Indirect pulp therapy[Title/Abstract]) #4 ((#1) AND (#2)) AND (#3)	6223 126580 8907 34
Cochrane	#1 MeSH descriptor: [Calcium Hydroxide] explode all trees #2 (calcium hydroxide):ti, ab,kw OR (Ca (OH)2):ti, ab,kw OR (Dycal):ti, ab,kw OR (calcium hydroxide cement):ti, ab,kw OR (CHC):ti, ab,kw (Word variations have been searched) #3 #1 OR #2 #4 (“mineral trioxide aggregate”):ti, ab,kw OR (“Mta”):ti, ab,kw OR (White MTA):ti, ab,kw OR (WMTA):ti, ab,kw OR (Grey MTA):ti, ab,kw (Word variations have been searched) #5 (indirect pulp capping):ti, ab,kw OR (IPC):ti, ab,kw OR (Indirect pulp treatment):ti, ab,kw OR (IPT):ti, ab,kw OR (Dental cavity liners):ti, ab,kw (Word variations have been searched) #6 #3 AND #4 AND #5	388 2182 2182 1062 2006 22
Google Scholar	MTA, mineral trioxide aggregate, Calcium hydroxide, Ca (OH)2, Dycal, indirect pulp therapy, indirect pulp treatment, Indirect pulp capping, primary molars, clinical or radiographic evaluation	356

Eligibility Criteria

Studies assessing the clinical and radiographic outcomes of indirect pulp treatment using MTA and calcium hydroxide in primary molars were included. Eligibility criteria were formulated based on the PICOS framework (PRISMA-P 2020):

• Population (P): Maxillary and mandibular primary molars in children aged 4 to 12 years

• Intervention (I): MTA as indirect pulp capping agent

• Comparison (C): Calcium hydroxide as indirect pulp capping agent

• Outcome (O): Clinical and radiographic success rate of MTA and calcium hydroxide as indirect pulp capping agents

• Study design (S): Randomized clinical trials (RCTs)

Studies conducted on animals, studies involving artificial teeth, non-randomized clinical trials, case reports, case series, review papers, conference abstracts, interviews, commentaries, responses to editors or authors, letters, and opinion articles were excluded.

Study Selection

Two reviewers independently screened the identified studies by evaluating their titles and abstracts. If the information provided in the title and abstract was inadequate for assessment, the full article was retrieved. During the second stage, full-text articles were examined in detail, and studies were selected according to the predefined eligibility criteria based on the PICOS framework. Any discrepancies in study selection were resolved through discussion with a third reviewer. Duplicate records identified during the database search were included only once.

Data Extraction

Data extraction from the selected studies was performed independently by three authors. Any conflicts were resolved through consensus involving two additional reviewers. The extracted data encompassed publication details (authors and year), study design, age of participants, type of teeth involved, sample size, materials used for indirect pulp treatment, and outcomes related to clinical and radiographic success.

Risk of Bias in Individual Studies

The risk of bias in the included randomized controlled trials (RCTs) was evaluated using the Cochrane Collaboration's Risk of Bias Tool. This assessment method examines seven key domains: (1) generation of the random sequence, (2) concealment of allocation, (3) blinding of participants, (4) blinding of outcome evaluators, (5) completeness of outcome data, (6) reporting bias, and (7) other potential biases. Each domain was individually assessed, and studies were categorized as having a low, high, or unclear risk of bias based on the criteria.

Data Analysis

Meta-analyses were performed using the random-effects model in RevMan 5.4 software (The Nordic Cochrane Centre, Copenhagen). Heterogeneity among studies was evaluated using the Q statistic and quantified with the I² index. Data related to reparative dentin formation and overall sample sizes were extracted from the included studies. When notable heterogeneity was detected (I² >50%), a random-effects model was employed; in cases of low heterogeneity (I² ≤50%), a fixed-effects model was utilized. The standardized mean difference in IL-1β levels between the intervention groups was computed, considering both variability within the comparison groups and differences in follow-up durations.

Results

Selection of Studies

An initial search of electronic databases yielded 412 studies. Of these, 20 were identified as duplicates and subsequently removed. The remaining 392 articles were screened based on their titles and abstracts, resulting in 12 studies considered suitable for further evaluation. Full texts of these 12 studies were retrieved and assessed for eligibility. Following a thorough evaluation, five studies^11–15 were excluded for not meeting the inclusion criteria. Ultimately, seven studies^3,5,16–20 were included in the systematic review. A manual search of the reference lists of the selected articles was also conducted, but no additional relevant studies were identified. The PRISMA flow diagram outlining the search and selection process is presented in Figure 1. Out of the seven included studies, five with comparable data were selected for meta-analysis to evaluate reparative dentin formation using MTA and calcium hydroxide in indirect pulp capping at a 6-month follow-up. The characteristics and findings of all seven studies included in the systematic review are summarized in Table 2.

Fig. 1:

PRISMA flowchart of the literature search and selection process

Table 2:

Characteristics of included articles

Author	Study design	Age (year)	Tooth	Sample size	Agents used for indirect pulp capping (Intervention)	Agents used for indirect pulp capping (comparator)	Final restoration after indirect pulp capping	Follow up	Outcomes
									Clinically	Radiographically
George et al.18	Randomized control trial	5 to 9 years	Primary molars	40	MTA	Calcium hydroxide (Dycal)	GIC	3rd and 6th month	Clinical evaluation was done for pain, tenderness to percussion, discoloration of teeth, and presence of sinuses. one patient had reported with sinus opening during the course of follow-up of the study with no cases of radiographic failure in the Dycal group. No clinical failure in MTA group.	The increase in dentin thickness was measured using Corel Draw software, Version 13, at baseline, third, and sixth month. At the end of 6 months, in MTA group tertiary dentin deposition was 0.143 mm of dentin and Dycal group, dentin deposit was 0.097 mm which were also statistically significant with a p-value of 0.004
Mathur et al.3	Randomized control trial	7 to 12 years	Mandibular second primary molars and permanent first molars	50 primary molar, 45 permanent first molars	GIC (Type VII) MTA	Calcium hydroxide	Light cure composite resin	8 weeks, 6 months and 1 year	Clinical and radiographic success rate with calcium hydroxide was found to be 93.5% and with 100% with MTA.	CBCT scan was performed, the scans were viewed and analyzed using i-CAT Vision software or dentine thickness. The mean percent increase in radiodensity values at 6 month post operative scan was between 78% and 84% in all groups.
Chauhan et al.5	Randomized control trial	4 to 9 years	Primary molars	45	MTA Biodentine	Calcium hydroxide	GIC (Type II)	3rd, 6th month	Patients were evaluated clinically for the presence of pain, tenderness, loss of restoration, abnormal tooth mobility, or presence of sinuses in relation to the tooth in question and recorded as yes or no at 3 and 6 months, respectively. Clinically, 100% success rate was observed.	Radiographically, the treatment was considered successful when no signs of periodontal space widening, interrupted lamina dura, interradicular radiolucency, and furcation involvement were seen. Statistically significant difference in dentin thickness was observed in all the groups. The increment in dentin bridge was more for MTA than Dycal
Stafuzza et al.17	Randomized Clinical trial	5 to 8 years	Primary molars	36	MTA Portland Cement with added Zirconia	Calcium hydroxide	RMGIC	6 and 12 months	At following-up period, clinical criteria local pain, dental mobility, percussion sensitivity, periapical abscess, and restoration failure such as secondary caries were evaluated. The overall success rate of the therapy for the three groups was 94.11% and no statistically significant differences occurred in the comparison among groups (p >0.05)	MTA group showed increase of the dentin barrier, over time, 6- to 12-month follow-up. The intergroup comparison revealed no statistically significant differences (p >0.05).
Divyashree R16	Randomized Clinical trial	4 to 9 years	Primary molars	50	MTA	Calcium hydroxide	RMGIC	1st, 6th month	Criteria for clinical success included no pain, no sensitivity to percussion, no swelling and/or fistula, no pathologic tooth mobility, Retention of the restoration (Marginal integrity). At the end of 1 and 6 months both groups showed good biological seal and maintained vitality of the pulp	The increase in dentin thickness was measured using Corel Draw software. There was highly statistically significant difference among all the experimental groups at the end of 6th month (p-Value < 0.001). The amount of reparative dentin formed was highest in Dycal group followed by MTA group.
Divyashree et al.19	Randomized Clinical trial	5 to 9 years	Primary molars	75	MTA Silver Diamine Fluoride	Calcium hydroxide	RMGIC	1, 3 and 6 months	Criteria for clinical success included no pain, no sensitivity to percussion, no swelling and/or fistula, no pathologic tooth mobility, Retention of the restoration (Marginal integrity). At the end of 1 and 6 months both groups showed good biological seal and maintained vitality of the pulp	Amount of reparative dentin formed was highest in the Dycal group followed by MTA group.
Gupta et al.20	RCT	3 to 9 years	Primary molars	36	White MTA Biodentine	Calcium hydroxide	RMGIC liner and composite restoration	24 hours, 1,3,6,12 months	Teeth were assessed for clinical parameters, pain, sensitivity, tenderness on percussion, swelling, mobility, and loss of capping material. The 100% success rate was achieved in the MTA group followed by Dycal group	Radiographic changes evaluated were furcation radiolucency, Widening of PDL, Pathological root resorption, Deviated axial inclination of underlying tooth, Postoperative caries, Calcific degeneration. MTA had 100% success rate for IPC and while 81.8% for Dycal

Risk of Bias

The Cochrane Collaboration's Risk of Bias Tool was employed to evaluate the methodological quality of the included randomized controlled trials. Each study was assessed across various domains and categorized as having a low, high, or unclear risk of bias. Adequate reporting of random sequence generation was observed in only two studies, while the remaining five provided insufficient information, resulting in an unclear risk rating. None of the studies reported on allocation concealment, which was therefore classified as high risk. Similarly, blinding of participants and investigators was absent across all studies, contributing to a high risk of bias in this domain. Blinding of outcome assessment was reported in just three studies, which were also considered high risk. Although all studies addressed attrition, none implemented appropriate strategies to manage participant dropouts. Additional concerns included lack of sample size calculation and absence of examiner calibration. Only one study reported performing a sample size estimation (Figs 2 and 3).

Fig. 2:

Overall risk of bias assessment graph of included randomized controlled studies

Fig. 3:

Risk of bias assessment of included randomized controlled studies

The funnel plot indicated a low likelihood of publication bias, as the studies were clustered toward the top half of the plot and exhibited a symmetrical distribution (Fig. 4).

Fig. 4:

Funnel plot; assessment of publication bias

Comparison of Reparative Dentin Thickness (mm) between MTA and Calcium Hydroxide

A meta-analysis was conducted using five studies that met the inclusion criteria and provided sufficient data for quantitative analysis. The results of the overall comparison have been depicted as a forest plot. As the meta-analysis of the included studies revealed substantial heterogeneity (I² = 57%), a random-effects model was employed for data synthesis. Participants treated with MTA exhibited increased reparative dentin thickness (mm) compared to those treated with calcium hydroxide, with a standardized mean difference of 0.45 (95% CI: −0.04 to 0.94; Z = 1.81). However, this difference was not statistically significant (p = 0.07) (Fig. 5).

Fig. 5:

Forest plot; comparison of reparative dentin thickness (in mm) between MTA and calcium hydroxide

Discussion

Premature loss of deciduous teeth can result in functional loss, disintegration of dental arches, malocclusion, and loss of esthetics. Thus, it is essential to preserve their vitality until the time of natural exfoliation in order to maintain the form and integrity of the arch.⁸ Managing teeth with deep carious lesions is very challenging. Indirect pulp treatment is considered a conservative approach for managing deep carious lesions in teeth without signs of pulpitis or those exhibiting reversible pulpitis. In this technique, a thin layer of demineralized but firm dentin is deliberately retained over the pulp to avoid exposure. Nevertheless, deep caries may still present a risk of bacterial infiltration into the coronal pulp, which can jeopardize the vitality of the pulp tissue. Consequently, careful consideration of the capping material is paramount. The chosen material should be biocompatible and possess antibacterial properties to foster a conducive environment for pulpal healing.²¹

In a systematic review by Santos et al., it was stated that the current evidence does not favor recommending any specific material for IPC in primary molars, as all materials demonstrate comparable efficacies in the studies examined. Additionally, there is no evidence supporting the superiority of using a liner, as advised in the American Academy of Pediatric Dentistry (AAPD) guidelines, over directly restoring cavities using alternative adhesive materials.²²

This systematic review evaluated seven randomized clinical trials, all of which compared the clinical and radiographic outcomes of mineral trioxide aggregate (MTA) and calcium hydroxide in the indirect pulp capping of primary teeth. Studies varied in their evaluation criteria, final restoration, follow-up period, and results. Clinical success was determined by the absence of symptoms such as pain, sensitivity to percussion, restoration failure, abnormal mobility, and the presence of sinus tracts. Radiographic evaluation focused on indicators such as furcation radiolucency, internal or external root resorption, widening of the periodontal ligament space, and the thickness of reparative dentin formation.

Based on the assessment of risk of bias in six studies, MTA was found to have a success rate that was either superior or comparable to that of calcium hydroxide in indirect pulp capping procedures. However, the clinical parameters were different. On the contrary, one article reported equal clinical success rates between MTA and calcium hydroxide, with a higher radiographic success observed in the calcium hydroxide group. Hence, a meta-analysis was subsequently conducted to further investigate and clarify the differences in success rates between MTA and calcium hydroxide in indirect pulp capping procedures.

The quality assessment of all seven included studies was carried out systematically. Adequate reporting of random sequence generation was observed in only two studies, while the remaining five lacked sufficient detail and were therefore classified as having an unclear risk of bias. Allocation concealment was not addressed in any of the studies, leading to its classification as high risk. Additionally, none of the studies reported blinding of investigators or participants, which was also considered a high risk. Blinded outcome assessment was documented in only three studies, resulting in a high-risk categorization. Although all studies reported attrition, none implemented strategies to address or compensate for participant dropouts. Other unspecified types of bias were also considered as associated with the lack of information on sample size estimation, examiner calibration, etc. Only one study had mentioned the sample size estimation.

In the study by George et al., it was reported that both MTA and Dycal demonstrated favorable clinical outcomes as IPT agents in primary teeth. However, radiographic findings indicated that MTA was more effective than Dycal. Additionally, greater dentin deposition was observed with MTA compared to Dycal at both the 3-month and 6-month follow-ups.¹⁸

The study conducted by Mathur et al. concluded that calcium hydroxide, type VII glass ionomer cement, and MTA were all comparably effective for indirect pulp treatment, as evaluated through both clinical and radiographic outcomes. The increase in reparative dentin thickness was measured by CBCT of teeth. The success rates were 93.5% for calcium hydroxide, 97% for glass ionomer cement (GIC) (type VII), and 100% for MTA, respectively. In this study, permanent teeth were included; however, the amount of reparative dentin formed in primary teeth was not specified separately.³

In a study conducted by Divyashree,¹⁶ the success of an IPT procedure was compared clinically and radiographically using Dycal, MTA, and silver diamine fluoride (SDF) as IPT materials on primary molars. It was observed that calcium hydroxide resulted in greater reparative dentin formation, followed by MTA. Stafuzza et al.¹⁷ mentioned that the MTA group exhibited an increase in dentin barrier formation during the 6- to 12-month follow-up period, and the overall success rate of the therapy was 94.11%. Gupta et al.²⁰ mentioned 100% clinical success in IPT with MTA and 75% with Dycal, but this study did not mention the increase in thickness (mm) of reparative dentin and considered direct pulp capping treatment along with indirect pulp capping.

The choice of final restorative material after indirect pulp capping also varied among the studies. Resin-modified glass ionomer cement (RMGIC) was used in three studies, type II GIC in two studies, while one study utilized light-cured composite, and another study employed an RMGIC liner in combination with composite restoration.

A meta-analysis was conducted on five studies that provided sufficient outcome data for quantitative evaluation. The meta-analysis of the selected studies revealed a heterogeneity exceeding 50%. Although the MTA group demonstrated a greater thickness of reparative dentin (in mm) compared to the calcium hydroxide group, the difference between the two was not statistically significant (p = 0.07). Meta-analysis of clinical outcomes was not feasible due to variations in the clinical criteria assessed.

The limited number of included trials, along with the small sample sizes within each study, may have impacted the ability to detect significant differences between the materials used for indirect pulp therapy in this review. Based on the findings of this systematic review and meta-analysis, it can be concluded that the use of MTA as an indirect pulp capping material is associated with a higher prevalence of dentin bridge formation. However, due to heterogeneity in the studies, conclusive determination of clinical success for any one material is challenging. Thus, the current findings do not support recommending one specific material as superior for indirect pulp treatment in primary molars. Further studies with reduced risk of bias are required to enhance the reliability of the results.

Conclusion

This systematic review evaluates whether calcium hydroxide or MTA, as an indirect pulp capping material, can attain adequate clinical and radiographic success for a duration of at least 6 months and up to 1 year. After considering all biases, it can be concluded that subjects treated with mineral trioxide aggregate demonstrated a greater thickness of reparative dentin compared to those treated with calcium hydroxide; however, it is not statistically significant. Based on these results, further studies are recommended to evaluate the long-term effectiveness of materials used for indirect pulp capping. Moreover, conducting more extensive, double-blind, randomized controlled trials is essential to establish more reliable clinical evidence.

Clinical Significance

This systematic review and meta-analysis highlights the effectiveness of MTA and Ca(OH)₂ as indirect pulp capping materials in primary molars with deep carious lesions, offering evidence-based insights to assist pediatric dentists in choosing the most appropriate material.

Orcid

Anija CK https://orcid.org/0009-0002-8153-2895

Ninawe Nupur S https://orcid.org/0000-0003-1403-4634

Shivani Sawant https://orcid.org/0009-0002-8176-6974

Honaje Nilam V https://orcid.org/0000-0001-6738-5046