Comparative Evaluation of Mineral Trioxide Aggregate (MTA), Ferric Sulfate, and Chitosan Hydrogel for Primary Molar Pulpotomy: An 18-Month Randomized Controlled Trial

Why is this study being done? When a child's tooth has a deep cavity, the decay can reach the soft inner part of the tooth called the pulp. A common treatment is called a pulpotomy - the dentist removes the infected part of the pulp and places a special material to protect the healthy root and save the tooth. Several materials are used for this treatment, but dentists do not yet agree on which one works best. This study compares three materials: (1) Mineral Trioxide Aggregate (MTA) - a well-known dental cement; (2) Ferric Sulfate (FS) - a liquid that stops bleeding; and (3) Chitosan Hydrogel - a new, natural gel made from shellfish shells. The goal is to find out which material keeps the treated tooth healthy for the longest time.

Who can take part? Healthy children aged 5 to 8 years who have at least one baby back tooth (primary molar) that needs a pulpotomy treatment may be eligible. Children with tooth pain, swelling, infection, or teeth that are too damaged will not be included. A parent or guardian must give written permission for their child to join the study.

What will happen during the study? 165 children will join the study and be randomly placed (like a coin toss) into one of three groups - each group receives a different pulpotomy material. The treatment is a routine pulpotomy done under local anesthesia (numbing injection) by an experienced pediatric dentist. After the pulpotomy material is placed, the tooth is sealed with a protective metal crown. Children will have check-up visits at 3, 6, 12, and 18 months. At each visit, the dentist checks the tooth by examination and by taking a small X-ray.

What are the possible risks? The risks are similar to those of any routine pulpotomy. Some children may feel mild soreness for 1 to 2 days after treatment. All three materials used in this study have been used in previous dental research. Children with shellfish allergies will be screened before enrollment.

What are the possible benefits? Participating children receive free professional dental treatment and regular check-ups at no cost for 18 months. The treatment aims to save the child's baby tooth, helping with chewing, speech, and guiding permanent teeth into the right position. The results of this study will help dentists choose the best treatment for children's teeth.

Is participation voluntary? Yes. Joining this study is completely voluntary. Parents and children may choose not to participate or may withdraw at any time without any effect on their future dental care. If a family does not join or decides to leave, their child will still receive standard dental treatment.

How is my child's information kept private? All information collected during this study is kept strictly confidential. Children's names are replaced with codes. Only the research team can access identifiable information. Results will be published in a way that does not identify any individual child.

Detailed Description

1. Background and Rationale Dental caries in primary molars frequently progresses to pulp involvement, necessitating pulpotomy - the surgical removal of infected coronal pulp tissue while preserving radicular vitality and function. Despite the availability of numerous pulpotomy medicaments, no consensus exists on the optimal agent, and comparative long-term data remain limited.

   Mineral trioxide aggregate (MTA) is a calcium-silicate cement recognized for its biocompatibility and bioactivity. Upon setting, MTA releases calcium and hydroxyl ions, creating an alkaline, antibacterial microenvironment that promotes dentinal bridge formation and radicular pulp preservation. Its major practical drawbacks are high material cost and handling difficulties, which limit universal adoption in pediatric clinical settings.

   Ferric sulfate (FS) is an inexpensive hemostatic agent that acts by forming ferric ion-protein complexes at the pulp stump surface, mechanically arresting hemorrhage. Unlike MTA, FS provides no bioactive stimulation of healing tissue. Histological investigations have demonstrated that FS-induced protein complexes can penetrate radicular pulp tissue over time, triggering persistent chronic inflammation and contributing to pathological internal root resorption - a recognized long-term liability.

   Chitosan is a naturally derived polysaccharide obtained by deacetylation of chitin from crustacean exoskeletons. It holds FDA approval for topical hemostatic and antimicrobial medical applications. Its relevant biological properties include intrinsic hemostatic capacity (through platelet activation and erythrocyte aggregation), broad-spectrum antimicrobial activity, biocompatibility, and biodegradability. In vitro data further suggest chitosan may promote fibroblast proliferation and angiogenesis, raising the possibility of active pulpal healing rather than mere hemostasis. However, clinical evidence supporting its use as a pulpotomy medicament in primary teeth is restricted to short-term studies (6-12 months) with small sample sizes. No randomized controlled trial has previously compared chitosan against both MTA and FS with simultaneous clinical and radiographic success criteria over an 18-month period. This trial is designed to address that evidence gap.

2. Study Objectives The primary objective is to compare the 18-month overall success rate - defined as simultaneous clinical and radiographic success - of MTA, FS, and a 2% chitosan hydrogel when used as pulpotomy medicaments in primary molars, and to test the null hypothesis that no statistically significant difference in outcome exists among the three materials.

   Secondary objectives include estimating pairwise risk differences (RD), relative risks (RR), and odds ratios (OR) with Bonferroni correction applied across three comparisons (adjusted α = 0.0167), and documenting clinical and radiographic success rates at each intermediate follow-up interval (3, 6, 12, and 18 months).

3. Trial Design This is a single-center, parallel-group, three-arm randomized controlled trial (RCT) conducted at the Pediatric Dentistry Clinic, Al-Mustansiriyah University College of Dentistry, Baghdad, Iraq, and reported in accordance with the CONSORT 2010 statement. Ethics approval was granted by the institutional review board (REC206, study number MUPEDO6); the trial is registered in the Thai Clinical Trials Registry (TCTR20260309003).

4. Randomization and Allocation Concealment A computer-generated randomization sequence using variable block sizes and a 1:1:1 allocation ratio was prepared by an independent statistician not involved in clinical procedures. Allocation concealment was maintained through sequentially numbered, opaque, sealed envelopes opened only after coronal pulp amputation and confirmation of hemostasis. This sequence ensures that teeth failing to achieve hemostasis within five minutes are excluded prior to group assignment, preventing selection bias related to pulpal status.

5. Blinding Complete operator blinding is not feasible due to the distinct physical forms of the three materials (liquid, powder, gel); this is an inherent limitation common to comparative pulpotomy trials. All participants and parents or guardians are blinded to group assignment. A calibrated pediatric dentist not involved in treatment performs all clinical outcome assessments, blinded to allocation at every follow-up visit. Radiographic assessments are conducted by an experienced endodontist, also blinded to group assignment. Data analysts remain blinded until statistical analysis is complete. Two pediatric dentists performed all procedures, with cases distributed approximately equally across operators and balanced across treatment groups; inter-operator reliability was confirmed on pilot cases (κ = 0.91). Intra-examiner consistency of the blinded clinical assessor was κ = 0.89.

6. Sample Size Sample size was calculated based on published MTA and FS success rate data, assuming an 18% absolute difference between groups (98% for MTA vs. 80% for FS), 80% statistical power, and α = 0.05. This calculation yielded 44 teeth per group. Accounting for an anticipated 20% attrition over 18 months, the final target sample was set at 55 teeth per group (total N = 165 teeth).

7. Interventions - Material Preparation and Application Protocols Ferric Sulfate (FS): Astringedent® 15.5% ferric sulfate solution (Ultradent Products Inc., South Jordan, UT, USA) was applied via a saturated cotton pellet to the pulp stumps for 15 seconds, followed by gentle irrigation with sterile saline. A thick mix of reinforced zinc oxide-eugenol cement (IRM®, Dentsply Sirona) was then placed over the pulp chamber floor.

   Mineral Trioxide Aggregate (MTA): White ProRoot® MTA (Dentsply Maillefer, Tulsa Dental Specialties, Switzerland) was mixed per manufacturer instructions and applied as a 2-3 mm layer directly over the pulp stumps.

   Chitosan Hydrogel (CHI): Medical-grade chitosan powder (Sigma-Aldrich, Product No. 448877; degree of deacetylation: 85%; molecular weight: 300-350 kDa) was dissolved in 1% (v/v) acetic acid at 2% (w/v) concentration under constant magnetic stirring at room temperature for 24 hours. The solution was neutralized to pH 7.0 ± 0.1 by dropwise addition of 1 M sodium hydroxide with continuous stirring and pH monitoring using a calibrated pH meter. The hydrogel was aseptically dispensed into sterile single-use glass vials, sealed, and sterilized by gamma irradiation at 25-30 kGy (Cobalt-60 source; Steris Nordion, Ottawa, Canada) in accordance with ISO 11137 standards. Post-sterilization quality control confirmed sterility per USP <71>, viscosity of 850 ± 50 cP at 25°C, and molecular weight of 290 ± 20 kDa. Vials were stored at 4°C in the dark and used within 3 months of manufacture. The hydrogel was applied 2-3 mm thick directly over the pulp stumps using a sterile 3 mL syringe.

   Common restoration protocol (all groups): A reinforced glass ionomer base (Fuji IX GP, GC Corporation) was placed over the pulp chamber floor, followed by cementation of a preformed stainless-steel crown (3M™ ESPE™) with occlusal adjustment. A postoperative periapical digital radiograph was taken immediately to serve as a quantitative baseline.

8. Follow-Up Schedule Participants attend scheduled follow-up visits at 3, 6, 12, and 18 months (primary endpoint). Each visit includes standardized clinical examination by the blinded assessor and a periapical digital radiograph evaluated by the blinded endodontist.

9. Statistical Analysis All analyses follow an intention-to-treat approach using IBM SPSS Statistics v26.0. Teeth lost to follow-up are classified as treatment failures. Baseline characteristics are compared using chi-square tests or one-way ANOVA as appropriate. Success rates are compared with chi-square or Fisher's exact tests, with Bonferroni correction applied for three pairwise comparisons (adjusted α = 0.0167). Effect measures include risk differences with 95% confidence intervals (Newcombe's method), relative risks, and odds ratios with exact confidence intervals. Number needed to treat (NNT) is calculated as 1/RD for statistically significant pairwise comparisons only.

10. Anticipated Limitations Operator blinding is not achievable due to the differing material forms, as noted above. Histological confirmation of pulpal healing is ethically precluded in a pediatric clinical trial. The chitosan formulation is prepared in-house; findings may not be directly generalizable to future commercial chitosan products. The single-center design may limit external generalizability. Variables such as pulp exposure size, carious lesion depth, and precise hemostasis time are not captured as independent covariates. The 18-month follow-up, while more extended than prior chitosan studies, may not capture late failures occurring before natural tooth exfoliation. No cost-effectiveness analyses, patient-reported pain outcomes, or quality-of-life data are collected.

11. Relation to Existing Evidence Systematic reviews and meta-analyses consistently demonstrate that calcium-silicate cements, including MTA, achieve higher pulpotomy success rates in primary molars compared with hemostatic agents. Ferric sulfate provides effective hemostasis but has been linked histologically to persistent inflammation and internal resorption over time. Prior chitosan pulpotomy studies are limited to short follow-up periods and small samples, and none have included a simultaneous three-arm comparison with MTA and FS using both clinical and radiographic success criteria at 18 months. This trial provides the most rigorous and temporally extended evaluation of chitosan's role in pediatric pulp therapy to date.

Inclusion Criteria:

• Children aged 5-8 years
• At least one carious primary molar requiring pulpotomy treatment
• Vital pulp confirmed at the exposure site after caries removal
• Tooth restorable with a stainless-steel crown
• Parent or legal guardian willing and able to provide written informed consent

Exclusion Criteria:

• Non-vital pulp (no bleeding after pulp amputation)
• History of spontaneous pain (suggesting irreversible pulpitis)
• Presence of soft tissue swelling or sinus tract related to the target tooth
• Pathological tooth mobility
• Radiographic evidence of:
• Internal or external pathological root resorption
• Furcation or periapical radiolucency
• More than one-third physiological root resorption
• Any condition preventing successful stainless-steel crown placement (e.g. Insufficient coronal tooth structure)

Individual participant data will not be shared because the study was conducted at a single center with a relatively small sample size, and participant consent obtained did not explicitly include provisions for data sharing beyond the primary analysis. Additionally, the ethical approval (Al-Mustansiriyah University College of Dentistry Ethics Committee, REC206) did not authorize public deposition of de-identified participant data. Data are available only to the research team for verification purposes upon reasonable request to the corresponding author, subject to institutional approval.