Reasons for Crown Failures in Primary Teeth: Systematic Review and Meta-Analysis

Background: Understanding long-term retention rates and complications associated with different materials for fabricating pediatric crowns for primary teeth is crucial for material selection and optimizing clinical outcomes. objectives: This systematic review aimed to descriptively analyze the crown-retention rates and complications associated with crown retention, as well as the biological and technical complications of pediatric crowns, for primary teeth. The meta-analysis reported herein was performed to estimate long-term (3-year and 5-year) retention rates of these pediatric crowns fabricated using various materials. Methods: Using the PICOS (Population, Intervention, Comparison, Outcomes, and Study design) paradigm, a systematic search was conducted between July and August 2023 in the Cochrane, Embase, and PubMed databases to identify randomized controlled trials (RCTs) and clinical (prospective and retrospective) studies reporting retention rates, complications of crown retention, and biological and technical complications. After selecting studies with a predefined set of selection criteria, data from included studies were used for a systematic review aimed at a descriptive analysis of factors associated with the failure of crowns for primary teeth. Data from the included RCTs were used for meta-analysis, wherein 3-year and 5-year crown-retention rates were estimated using Poisson regression models. Results: This systematic review included 13 RCTs and 5 clinical studies on dental crowns for primary teeth, involving 454 children (1172 crowns) in RCTs and 810 children (2667 crowns) in clinical studies. The median follow-up durations were 12 months for RCTs and 20.8 months for clinical studies, with a 10.6% (124/1172) dropout rate in RCTs. Meta-analysis of pooled 5-year retention rates for different crown materials revealed the following retention rates: 88.90% for compomer crowns, 92.18% for composite resin crowns, 90.30% for resin-modified glass ionomer cement (RMGIC) crowns, and 97.88% for stainless steel crowns. Additionally, strip crowns exhibited a retention rate of 83.48%, while zirconia crowns had a retention rate of 97.09%. Poisson regression estimated 3-year and 5-year crown-retention rates, indicating good outcomes across materials. Complications included secondary caries (up to 21.8% in zirconia crowns) and marginal adaptation issues (up to 22.2% in compomer crowns). These findings highlight material-specific considerations necessary for optimizing outcomes in pediatric dental crown treatments. Conclusions: While retentive complications such as chipping, material loss, and fractures do occur across materials, compomer, composite resin, stainless steel, strip, and zirconia crowns all have clinically acceptable retention rates. However, the differences in biological and technical complications between materials may provide insights for selecting appropriate materials for pediatric crowns based on clinical considerations.