We aimed to compare subjective (S) vs. objective (O) selective carious tissue removal using hand-excavation versus a self-limiting polymer bur, respectively. A community-based single-blind cluster-randomized controlled superiority trial was performed. This is a 1-year-interim analysis. 115 children (age 7–8 years) with ≥1 vital primary molar with a deep dentin lesion (>1/2 dentin depth) were included (60 S/55 O). The cluster was the child, with eligible molars being treated identically (91 S/86 O). Cavities were prepared and carious tissue on pulpo-proximal walls selectively removed using hand instruments (S), or a self-limiting polymer bur (Polybur P1, Komet). Cavities were restored using glass-hybrid material (Equia Forte, GC). Treatment times and children’s satisfaction were recorded. Generalized-linear models (GLM) and multi-level Cox-regression analysis were applied. Initial treatment times were not significantly different between protocols (mean; 95%CI S: 433; 404–462 sec; O: 412; 382-441 sec; p = 0.378/GLM). There was no significant difference in patients’ satisfaction (p = 0.164). No pulpal exposures occurred. 113 children were re-examined. Failures occurred in 22/84 O-molars (26.2%) and 26/90 S-molars (28.9%). Pulpal complications occurred in 5(6%) O and 2(2.2%) S molars, respectively. Risk of failure was not significantly associated with the removal protocol, age, sex, dental arch or tooth type (p > 0.05/Cox), but was nearly 5-times higher in multi-surface than single-surface restorations (HR: 4.60; 95% CI: 1.70-12.4). Within the limitations of this interim analysis, there was no significant difference in treatment time, satisfaction and risk of failure between O and S.