Comparison of Gingival Health Outcomes Between Prefabricated Zirconia Crowns and Stainless Steel Crowns in Primary Molars: A Randomized Split-Mouth Clinical Trial

This clinical trial is a prospective, randomized, split-mouth controlled study designed to compare the long-term effects of prefabricated zirconia crowns (PZCs) and stainless steel crowns (SSCs) on gingival health, plaque accumulation, and parental satisfaction in primary molars of young children. The study addresses the need for evidence on how these restorative materials influence periodontal outcomes, given the conflicting data in existing literature regarding their biocompatibility, esthetics, and impact on gingival tissues. SSCs have been the standard for durability and cost-effectiveness in pediatric dentistry, but their metallic appearance and potential for plaque retention due to marginal microgaps raise concerns for esthetics and gingival inflammation. PZCs, offering superior esthetics and a polished surface, may provide advantages in reducing plaque adherence and improving mucosal compatibility, though long-term comparative data are limited.

This trial will employ a split-mouth design at the Pediatric Dental Clinic of Qassim University, Buraydah, Al-Qassim Province, Saudi Arabia. This intra-subject approach minimizes inter-individual variability in factors such as salivary composition, microbial ecology, brushing habits, dietary sugar intake, and systemic health, enabling direct comparison of the two crown types within the same child. One hundred healthy children with bilateral primary molars requiring full-coverage restorations will be enrolled. Randomization using a computer-generated sequence with allocation concealment via opaque envelopes opened chairside post-preparation will be implemented. Contralateral molars will receive either a PZC or SSC (randomly assigned), ensuring balanced distribution.

Tooth preparation will be standardized under local anesthesia (2% lidocaine with 1:100,000 epinephrine): pulpotomy/pulpectomy as indicated, circumferential reduction (1-1.5 mm) with tapered diamond burs, occlusal clearance (1.5-2 mm), and proximal adjustments. PZCs will be fitted without crimping for optimal marginal adaptation (<50 μm target), while SSCs will undergo mechanical crimping for tight cervical fit (<30 μm discrepancy). Both will be luted with resin-modified glass ionomer cement (RelyX™ Luting Plus, 3M™) for fluoride release and reliable bonding. Assessments will be conducted by two independent, calibrated examiners (inter-rater kappa >0.80) blinded to crown type via opaque cheek retractors.