Repair Versus Replacement of Failed Restorations in Primary Teeth

Restoration survival will be assessed based on clinical evaluation of the restorations at 6, 12, 18, and 24 months. A restoration will be considered to have survived when it remains clinically satisfactory according to the following criteria.

Single-surface restorations will be considered satisfactory when scored as 0 (restoration present and satisfactory), 1 (restoration present, with a slight marginal defect and/or surface wear of less than 0.5 mm in depth, with no need for repair), or 7 (restoration present, with gradual wear involving larger areas of the restoration but less than 0.5 mm in depth at the deepest point, with no need for repair), according to Frencken et al. (1996). Multiple-surface restorations will be considered satisfactory when scored as 00 (restoration present and satisfactory) or 10 (restoration present, with a slight marginal defect and/or surface wear of less than 0.5 mm in depth, with no need for repair), according to Rôlevald et al. (2006).

Treatment success at 24 months will be assessed as a binary outcome. All participants will be clinically evaluated at 24 months, and each treated tooth will be classified as either successful or unsuccessful. Treatment will be considered successful when the treated tooth requires no operative reintervention during the 24-month follow-up period and remains asymptomatic, according to the clinical criteria described above. Natural exfoliation of the treated tooth during the follow-up period will also be considered a successful outcome. Treatment failure will be defined as the need for operative reintervention due to disease progression or treatment failure, including endodontic treatment or extraction.

Before randomization, parents or guardians and the child will receive a standardized explanation of the two therapeutic approaches under investigation (replacement and repair of restorations). To aid comprehension, illustrative images generated by artificial intelligence will be presented, depicting each procedure in a standardized manner. Parents or guardians and the child will then be asked: "If you could choose, which treatment would you prefer?" Responses will be recorded as: replacement, repair, or no preference.

The total treatment time will be measured by a research assistant using a digital stopwatch. Timing will start at the beginning of the clinical intervention and stop immediately after its completion. Time will be recorded and expressed in minutes (min).

The child's perception of the treatment will be assessed immediately after completion of the procedure using the Facial Image Scale (FIS). The scale will be presented by the research assistant, in the absence of the operator, in order to minimize the professional's influence on the response. The child will be asked to indicate the image that best represents how they felt during the treatment, following the question: "How did you feel during the treatment?" The FIS consists of five facial images ranging from a very happy to a very sad expression, allowing assessment of the child's acceptance of the experience.

Immediately after completion of the treatment, parents or guardians will answer the following question: "How satisfied are you with the treatment performed on your child?" The response will be recorded on a five-point Likert scale, ranging from very dissatisfied to very satisfied.

At 30 days after the procedure, parents or guardians will be presented again with illustrative images of the two therapeutic approaches, accompanied by the same standardized explanation used in the initial assessment. They will then be asked: "If you could choose again, which treatment would you choose for your child?" Responses will be recorded as repair, replacement, or no preference.

Additionally, a cost-effectiveness analysis will be conducted comparing the repair and replacement of defective restorations in primary molars over 24 months of follow-up. Restoration survival over this period will be used as the effectiveness measure for the economic analysis. The analysis will adopt the perspective of the Brazilian public health system and will consider only direct treatment costs.

The direct costs associated with the repair and replacement of restorations will be compared, considering the clinical treatment time and materials actually used in each procedure. Treatment time will be measured by a research assistant who is not involved in performing the interventions and will be used to estimate the dental professional's labor cost based on the cost per hour of professional work. Material costs will be estimated based on the actual amount consumed during each procedure and the prices obtained from three quotations from different suppliers, with the mean value of the quotations used for cost calculation. Costs will be expressed in Brazilian reais (BRL), based on the prices prevailing during the study period.