A randomized clinical trial of cavity liners after selective caries removal: one-year follow-up

Abstract Alternatives for the treatment of caries disease, such as minimally invasive approaches, have been developed in recent years. Objective: To carry out clinical and radiographic evaluations of three cavity liners after selective caries removal. Methodology: Thirty-six primary molars with deep occlusal caries lesions without pulp involvement (from children of both genders, aged between 5 and 8 years) were randomly divided into the following groups: calcium hydroxide cement (CHC) group; mineral trioxide aggregate (MTA) group and Portland cement with added zirconium oxide (PCZ) group. The following-up period was 6- and 12-month. The clinical and radiographic success rates were evaluated through chi-square test. The radiographic measurements were compared by ANOVA followed by Tukey's test (p<0.05). Results: Thirty-six patients were included, but thirty-four returned for 12-month follow-up. The overall success rate of the therapy for the three groups was 94.11% and no statistically significant differences occurred in the comparison among groups (p>0.05). Nineteen radiographs were selected to measure the dentin barrier thickness. The intragroup comparison presented a statistically significant increase of the dentin barrier for all groups, at 12-month follow-up. However, the MTA group showed increase of the dentin barrier, over time, 6- to 12-month follow-up. The intergroup comparison revealed no statistically significant differences (p>0.05). Conclusion: The clinical and radiographic data showed that all cavity liners provided effective treatment of primary teeth after selective caries removal.


Introduction
The selective caries removal is a minimally invasive approach consisting of non-removal of the affected dentin followed by hermetic sealing of the cavity. [1][2][3] This technique reduces the number and diversity of the bacteria, stops the caries process, 4,5 and decreases the risk to pulp exposure, [4][5][6][7] presenting clinical advantage over complete caries removal. 5 For restorative interventions cavity lining has been recommended for a long time. 8 Researches has shown that Calcium Hydroxide (CH) promotes a decrease in the number of cariogenic bacteria, favoring remineralization. 9 However, a systematic review of incompletely excavated teeth found a tendency to fail in CH lining cavities despite the adequacy of this protective material for deep carious lesions. 6 CH exhibits unfavorable effects such as internal resorption, degradation over time and defects in dentin barrier formation. 10  properties. 12,13 There are few studies that use PC in human teeth, but this material presented satisfactory clinical and radiographic results. [12][13][14][15] Current evidence indicates that less invasive strategies are effective for managing carious lesion, 8   The clinical and radiographic success rates were evaluated through chi-square test. The radiographic measurements were compared by ANOVA followed by Tukey's test. A level of significance of 5% was adopted.

Patient sample and study design
Of 578 evaluated molars, 542 did not fill the inclusion criteria and were excluded from the study.

Clinical and radiographic assessment
The systematic and casual error was verified, and no statistically significant differences occurred (p>0.05). Thirty-six patients were included, but thirty- Values represent the number of teeth treated, per group However, the MTA group showed increase of the dentin barrier, over time, 6-to 12-month follow-up ( Table 3).
The intergroup comparison revealed no statistically significant differences (p>0.05).

Discussion
The present randomized clinical study applied a standard methodology well described in the literature 11,17,22,23 to evaluate the in vivo response of different cavity liners in procedures of selective caries removal from primary teeth, after 12 months of follow-up. The difficulty of this technique, however, is the subjective criterion to evaluate the amount of carious tissue that must be removed. 3 Recently, it has been determined that the best guidance is the tactile sensation of the operator. 24 In this study, the dentin consistency was taken into consideration. The selective caries removal was performed until firm dentin, resistant to cut, with a leather-like texture. 3,24 Currently, the literature lacks consensus on the ideal liner to be used on the remaining affected dentin. CH is effective in reducing bacteria. 25

Group
Immediate post-operative 6-months control 12-months control p CHC  This study was the first randomized clinical trial that compared the clinical and radiographic outcomes of CH, MTA, and PC after the selective caries removal in primary teeth, however, the number of teeth used for analysis was small and more studies will be required. The occlusal caries that reach two-thirds of the dentin, without pulp involvement, was a difficult finding, since interproximal caries and deep cavities with pulp involvement were more commonly found in dental practice. The findings of this study are an