Ethical approval for the research protocol was obtained from the Research Ethics Committee, Faculty of Dentistry, Cairo University with the reference code (18 10 53).
The present study was a parallel, randomized clinical trial (RCT) with 1:1:1 allocation ratio; conducted in Pediatric Dentistry and Dental Public Health Department, Faculty of Dentistry, Cairo University. In this study, patients, their guardians and statistician were blinded.
According to Godhi et al 3 and Olatosi et al 10, a sample size of 72 second primary molars (including drop-outs) was determined using G*power Program (University of Düsseldorf, Düsseldorf, Germany).
The study population included four to eight years old, apparently healthy and cooperative patients who presented at the Pediatric Dental Clinic, Faculty of Dentistry, Cairo University and had deep carious mandibular second primary molars indicated for pulpotomy. Written consent was obtained from the parent/guardian after a comprehensive explanation of the study protocol. Personal, medical, dental history and clinical evaluation were obtained from all patients participating in this study.
The criteria for inclusion in this study were:
- Pulp exposure due to caries removal or after a traumatic pulp exposure.11
- No history of spontaneous pain, tenderness to percussion, tooth mobility.
- No clinical evidence of pulpal inflammation or degeneration, such as history of swelling or presence of sinus tract.
- Restorable teeth.
- Absence of radiographic evidence of internal or external root resorption, pulpal calcification, or osseous disease (periapical or furcation infection).
On the other hand, teeth were excluded if:
- Evidence of necrosis after access cavity preparation.
- Hemostasis could not be achieved within three min after direct contact with a wet cotton pellet, after removal of coronal pulp tissue.
Randomization & allocation concealment:
Simple randomization was done, to allocate the molars, using computer sequence generation (www.random.org) by the second investigator with 1:1:1 allocation ratio into three groups (n=24) based on the pulp capping materials. Group 1: NHA (Straumann Bone Ceramic, Switzerland), Group 2: MTA (Angelus- Londrina, Brazil), and Group 3: FC (Formacresol, Prevest DenPro Limited, India) as pulp medicaments. Allocation concealment was done using opaque envelopes.
Sequence generation was done for the molars number (1 to 72) using computer sequence generation (www.random.org). The sequence generator icon was selected from the home page, the sample size was specified, and the format in two columns was ordered. The result was then copied to group 1, group 2 and group 3, with randomized molars’ numbers (24 numbers in each group).
Allocation Concealment Mechanism:
Each of the 72 papers numbered from 1 to 72, was individually packed by the second investigator in an opaque envelope after folding each paper eight folds. Each patient was asked to pick an envelope, after their enrollment in the study and before the beginning of treatment. Numbers in the envelopes determined the group assigned for each molar.
The study was registered with clinicaltrials.gov under the title: Success Rate of Three Capping Materials: A randomized Clinical Trial, with an identifier: NCT03833557.
Preoperative periapical radiograph using periapical film size two (Speed D Film, Kodak, US) was taken for the molars considered for treatment; for proper radiographic diagnosis.
The first investigator performed the pulpotomy procedure. Under local anesthesia and rubber dam isolation, caries was removed and deroofing of the pulp chamber was performed using a #330 high-speed carbide bur mounted in a water-cooled high-speed turbine. The coronal pulp tissue was amputated using a sterile sharp spoon excavator. The pulp chamber was irrigated with normal saline. Pulp hemostasis was achieved using a sterile wet cotton pellet applied for two to three minutes.
In Group 1: NHA was used according to the manufacturer’s instructions; it was mixed with saline and was placed over the pulp stumps using amalgam carrier and condenser.
In Group 2: MTA powder was mixed with sterile water in a 3:1 powder/water ratio, according to the manufacturer’s instructions to obtain a thick creamy paste, placed using a messing gun and compacted against the pulp orifices with a condenser over a moist cotton pellet.
In Group 3: After blood clot formation, a sterile cotton pellet moistened with FC (squeezed twice) was placed over the radicular pulp for 5 minutes and then removed. A thick mix of Zinc Oxide Eugenol (ZOE) paste was placed over the FC fixed tissue using a cement spatula and condensed as previously mentioned.
All molars were finally restored with stainless steel crowns (3M, ESPE, Unitek, US) cemented with GI cement. An immediate postoperative radiograph using periapical film size two was taken. Oral hygiene measures were given to the patients.
Clinical & radiographic evaluation:
All treated patients were followed up by the other investigator at three, six and twelve months after the pulpotomy for clinical and radiographic evaluation. Blinding was not feasible as NHA appears radiolucent in the radiographs.
Molars were judged as clinically successful if they met the following criteria: Absence of sensitivity, pain, tenderness to percussion, abscess, fistula or tooth mobility. Radiographic failure was defined according to radiographic failure score 12 , Table (1) .
For the three groups, clinical and radiographic findings at three, six and twelve months postoperatively were assessed. The difference in success rate between groups at the same time point was evaluated using Chi square test. Significant level was set at p <0.05. Statistical analysis was performed using a commercially available software program SPSS version 21 (Chicago, IL, USA).