An interventional study of Repair of Failed Restoration and Replacement of Failed Restoration in Dental Caries, Restoration Defects and Primary Teeth, sponsored by University of Sao Paulo. Not yet recruiting at 1 site in Brazil. Open to participants aged 4 Years to 8 Years. Per ClinicalTrials.gov, last updated 2026-09-21.
Sponsored by University of Sao Paulo · Not applicable, Interventional, and Treatment
Dental caries affect approximately 573 million children globally, and the management of failed restorations is a frequent clinical issue in pediatric dentistry. Although complete replacement of restorations is traditionally the most commonly adopted approach, repair represents a minimally invasive alternative that preserves healthy dental structure and reduces the risk of pulpal complications. Studies in permanent teeth demonstrate that repair may present longevity similar to replacement; however, there is no robust evidence regarding this comparison in primary teeth. This randomized controlled clinical trial, with parallel groups and a 1:1 allocation ratio, aims to evaluate the non-inferiority of repair compared with replacement of failed restorations in primary molars, using encapsulated high-viscosity glass ionomer cement. Children aged 4 to 8 years with at least one failed restoration eligible for repair in primary molars will be included. Randomization will be stratified by number of surfaces. Teeth (n=824) will be randomly allocated to one of the groups: repair or replacement. The primary outcome will be restoration survival at 24 months. Cost-effectiveness will be evaluated as a secondary outcome. Statistical analysis will use Kaplan-Meier curves and Cox regression with shared frailty (¿=5%).
Exclusion Criteria:
Repair of Failed restoration in primary teeth.
Procedure: Repair of Failed Restoration
Replacement of Failed Restoration in primary teeth.
Procedure: Replacement of Failed Restoration
Prior to the procedure, when needed, local anesthesia with 2% lidocaine and 1:100,000 epinephrine will be used, with relative isolation (cotton rolls and saliva ejector). The defective area will be clinically identified. When present, carious tissue will be selectively removed with hand instruments (dentin curettes) suited to the cavity, preserving as much of the intact original restoration as possible. If no hand instrument fits, the cavity will be enlarged with a small spherical diamond bur at high speed under cooling. The surface will be conditioned with 20% polyacrylic acid (GC Cavity Conditioner) for 10 s, rinsed abundantly, and dried with cotton pellets. For proximal surfaces, a metal matrix and wedge will be placed before the GIC. The capsule will be activated, mixed for 10 s, inserted with an applicator, and adapted by digital pressure with petroleum jelly. Occlusion will be checked with articulating paper and adjusted; surface protection applied with petroleum jelly.
Prior to the procedure, when needed, infiltrative local anesthesia with 2% lidocaine and 1:100,000 epinephrine will be administered. Relative isolation will be used, with cotton rolls and a saliva ejector. Complete removal of the defective restorative material will be performed with spherical diamond burs at high speed under cooling, complemented by round burs at low speed to remove remaining restorative material. Selective removal of carious tissue, when present, will be carried out with hand instruments (dentin curettes) suited to the cavity, preserving soft or leathery dentin according to the depth of the lesion. The new restoration will then be placed following the same protocol described for the repair group: conditioning with 20% polyacrylic acid (GC Cavity Conditioner) for 10 s, rinsing and removal of excess water; placement of a metal matrix and wedge, when needed; insertion of the GIC into the cavity; adaptation by digital pressure with petroleum jelly; occlusal adjustment; a
Restoration survival rate
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).
Time frame: 24 months
Treatment success rate
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.
Time frame: 24 months
Parents' and Child's Preference
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.
Time frame: Before randomization and prior to treatment
Treatment Time
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).
Time frame: From the beginning to the completion of the treatment procedure
Child's perception of treatment measured by the Facial Image Scale
The child's perception of the treatment will be assessed immediately after completion of the procedure using the Facial Image Scale (FIS). The scale consists of five facial images scored from 1 to 5, ranging from a very happy expression (score 1) to a very sad expression (score 5). Higher scores indicate a more negative perception of the treatment, whereas lower scores indicate a more positive perception. The scale will be presented by a research assistant, in the absence of the operator, in order to minimize the professional's influence on the child's 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?"
Time frame: Immediately after the procedure (Day 0)
Parents'/Guardians' satisfaction with the treatment using five-point Likert scale
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 using a five-point Likert scale, ranging from 1 (very dissatisfied) to 5 (very satisfied). Higher scores indicate greater satisfaction with the treatment, whereas lower scores indicate lower satisfaction.
Time frame: Immediately after the procedure (Day 0)
Parents'/Guardians' Willingness to Choose the Treatment Again
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.
Time frame: 30 days after the procedure
Incremental cost-effectiveness ratio (ICER) of restoration repair versus replacement
A cost-effectiveness analysis will be conducted comparing the repair and replacement of defective restorations in primary molars over 24 months of follow-up. Costs will be measured as direct treatment costs in Brazilian reais (BRL), and effectiveness will be measured as restoration survival over 24 months. The incremental cost-effectiveness ratio (ICER) will be calculated as the difference in mean costs between the repair and replacement groups divided by the difference in mean effectiveness between the groups. The ICER will therefore represent the additional cost per additional surviving restoration associated with one treatment strategy compared with the other. The analysis will adopt the perspective of the Brazilian public health system and will consider only direct treatment costs..
Time frame: 24 months
Mean direct treatment cost per restoration in Brazilian reais (BRL)
The direct costs associated with the repair and replacement of restorations will be calculated and 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. The total direct treatment cost for each restoration will be calculated by summing the labor and material costs and will be expressed in Brazilian reais (BRL), based on the prices prevailing during the study period. The mean direct treatment cost per restoration will be reported for each treatment group.
Time frame: Immediately after the procedure (Day 0)
Plan to share: Yes — Anonymized individual participant data (IPD) collected from parents and/or caregivers will be shared, including demographic and study-related data, treatment preference, treatment satisfaction, willingness to choose the treatment again, and other participant-level outcome data collected during the study. All data will be fully anonymized prior to sharing to prevent identification of participants or disclosure of sensitive information.
Supporting information: Study protocol, Sap
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University of Sao Paulo