Study design

In this double-blinded parallel-group randomised controlled trial, we plan to enrol 384 patients, from 5 to 9 years. Clinical and radiographical success will be assessed after 6, 12 and 24 months. Children and their parents will be blinded as to which treatment they will be submitted. Blinding the operator during the liner application step will not be possible. Clinical and radiographical follow-up examinations will be blinded to treatment group allocation. We plan to use the intention-to-treat principle to deal with the data missing at random due imbalanced loss to follow-up by assigning poor outcome to all patients lost in the group that fared better and good outcome to all patients lost in the group that fared worse (extreme case analysis).15. During the study, participants who need other dental treatments will be attended by a paediatric dentist at the Pediatric Dentistry Clinic of the University of São Paulo, Bauru, Sao Paulo, Brazil.

Study setting

Participants will be recruited at municipal schools of Bauru, Sao Paulo Brazil. The children and legal guardians will be instructed about the research and will read and sign a free and clarified consent term. The treatments will take place in the Pediatric Dentistry Clinics of University of Sao Paulo (Bauru, Sao Paulo, Brazil). Efforts will be made to achieve adherence by explaining the treatment importance. Recruitment will take place from September 2019 to August 2020. Each participant will be enrolled in the study for approximately 25 months (1 month for treatment plus 24 months of follow-up).

Eligibility criteria

Inclusion criteria will comprise children aged 5–9 years, from both genders, with restorable maxillary/mandibular first/second primary molars with deep occlusal and occlusoproximal cavities (deep carious lesion reaching pulpal quarter with a zone of dentine separating the lesion from the pulp),16 without pulp exposure; no internal/external root resorption, without mobility; no history of spontaneous pain, fistula/abscess and lesion at furcal/periapical area. Exclusion criteria will be the presence of systemic diseases and history of allergic reaction to dental materials.8 14

Allocation and blinding

Randomisation will be performed after the inclusion of the teeth in the study. The allocation concealment technique will be used to avoid selection bias during the assignment of the selected teeth and the liner material. One molar per patient will be randomly allocated (Microsoft Excel) in the study groups. If the patient has more than one tooth to be included in the study, the tooth mostly meeting the inclusion criteria will be chosen. The selected teeth will be distributed through computerised stratified sampling (Microsoft Excel) according to the child age in months, dmtf index and type of cavity (occlusal or occlusoproximal).17 This study will be composed by three groups according to each material: CH (Hydro C/Dentsply, Philadelphia, USA)—group 1 (G1); MTA (Angelus Londrina PR, Brazil)—group 2 (G2) and without liner—group 3 (G3). The following-up period will be 6, 12 and 24 months (figure 1). An equal number of patients will be assigned to the intervention groups.

• Download figure
• Open in new tab
• Download powerpoint

Figure 1

Flowchart of the study. ANOVA, anaylsis of variance

Randomisation will be independent, that is, the patients and legal guardians will remain blinded to intervention group status. The intervention group identifier will be assigned at random and will not be identified during data analysis, such that data analysts will also remain blinded. This clinical trial follows the guidelines for randomised clinical trials (Standard Protocol Items: Recommendations for Interventional Trials checklist).

Interventions

Clinical analyses will be based on a form and will be performed by two trained and calibrated operators who will be blinded to the clinical procedure. The operators will be trained on the procedures previously on 10 primary molars that will not be part of the study sample. Radiographical procedures will ensure accurate measurement of reference points, each scanned image will be measured more than once by two trained and calibrated examiners with a 15-day interval between measurements. The measurements on the digitised images will be performed by two trained and calibrated investigators who will be blinded to the clinical procedure. The patients will be blinded to the pulp liner materials. It will not be possible to blind the operator during pulp liner application. The statistician will be blinded to patient allocation. A detailed anamnesis and clinical examination will be performed. Then a periapical radiograph of the eligible primary molars will be taken to verify the periapical conditions. All radiographs will be standardised using universal acrylic positioning stents. Satisfied all inclusion criteria of the study and after informed consent is given, treatment will be randomly provided in the second visit. After local anaesthesia and rubber dam isolation, the cavity preparation will be performed using water-cooled diamond instruments. Caries will be completely removed from the lateral walls and enamel–dentine junction with the aid of low-speed round burs until hard dry dentin remains.18 SCTR will comprise selective removal to firm dentine on pulpal wall with the aid of hand excavators. The pulp liners will be mixed according to the manufacturers’ instructions and gently placed on pulp wall at a thickness of approximately 1 mm. The final restorations will be performed with resin-modified glass ionomer cement (Vitremer 3M/ESPE).19 20 If pulpal exposure occurs during excavation, the tooth will be excluded from the study.

Outcomes

The primary outcome of the study will be success of the in vivo response of dentine–pulp complex (not requiring pulp treatment and maintenance until the normal exfoliation period). The evaluated criteria will include clinical (history of pain, dental mobility, sensitivity to percussion, abscess/fistula and restoration failure) and radiographical aspects (presence/absence of internal/external resorption, signs of furcal impairment, advanced rhizolysis stage and restoration failure including fracture and loss). Secondary outcome comprises the dentine barrier formation. All radiographs will be subsequently digitised and transferred to the computer to be analysed. A baseline radiograph with grid was made with an X-tension C-one P-arallelying (XCP) holder. To assess the dentin barrier thickness, the measurements on the digitised radiographs will be performed at baseline, 6-month, 12-month and 24 month following-up through Corel Draw X3 software (V.13).21 To perform the measurement of dentin barrier thickness, the most central point located in the pulp wall of the cavity will be considered. All measurements of the scanned images will be performed by two trained and calibrated investigators who will be blinded to the clinical procedure and the pulp liner materials22.

Sample size

The sample size calculation will be performed based on data from a pilot study. For the sample calculation, alpha and beta errors of 5% and 20% will be considered, respectively. The sample size also provides 80% power. The sample will be of 103 teeth per group to detect significant differences. A drop-out rate of 20% will be estimated then, the number of eligible teeth will be 128. Thus, the final sample size for this study will be 384 teeth (128 for each study material).

Statistical evaluation

All data will be analysed using the PASW Statistics V.20 software (SPSS). During all study, two trained and calibrated examiners will evaluate the treated teeth clinically and radiographically. Interexaminer and intraexaminer reliability will be verified by casual and systematic error. The Kolmogorov–Smirnov test will be adopted to test the normality of continuous variables, which will be expressed as median for the variables with a non-normal distribution and a mean value±SD for the variable with a normal distribution. Comparisons among groups will be performed by using the χ² test and analysis of variance, followed by Tukey test. The level of significance of 5% will be adopted for all comparisons. The effects of possible confounders (number of involved surfaces, maxillary/mandibular, first or second molar, age, gender cavity size) will be analysed. The relative cost-effectiveness will be described via the net-benefit approach. The multiple imputation methods will be used to verify sensitivity analysis with regard to missing values. The logistic regression will be applied, and the degrees of this association will be measured via using the OR and 95% CI.

Trial status

The trial was registered at ensaiosclinicos.gov.br and the study is open for recruitment in July (). Recruitment will take place from September 2019 to August 2020.

Data collection methods, management and monitoring

The clinical and radiographical aspects of teeth will be evaluated at 6, 12 and 24 months after SCTR procedures. Data will be collected and registered on case report forms by trained researchers blinded to group allocation. Data quality will be ensured by validation checks that include missing data. Clinical and radiographical data will be inserted directly in clinical and radiographical evaluation forms. The data of the scanned X-rays will be entered in Corel Draw X3 software for further analysis. The data will be monitored by an independent clinical research assistant, one statistician and one dental surgeon. No interim analysis beyond that described above is planned. Data monitoring committee (DMC) will independently check data and report any problem. DMC is independent from the sponsor and competing interests.

Ancillary and post-trial care

After completing the study, participants will continue to receive dental treatments, if needed, in the Pediatric Dentistry Clinics of University of Sao Paulo, Bauru, Sao Paulo, Brazil.

Harms

It is unlikely that the procedures will result in any adverse effects. The side effects are usually those expected in any conventional dental treatment performed in paediatric dentistry clinical practice.

Patient and public involvement

Neither patients nor the public will be involved in the design of this study. Our study will only evaluate caries removal treatment in children as described.

Ethics and dissemination

Availability of data and materials

The datasets generated and/or analysed during the current study will be available from the corresponding author on reasonable request.