Clinical and radiographic performance of preformed zirconia crowns and stainless-steel crowns in permanent first molars: 18-month results of a prospective, randomized trial.

BACKGROUND: The treatment of young permanent first molars with extensive carious tissue loss may often require restoration with preformed crowns. This study compared the clinical and radiographic performance of stainless-steel crowns (SSCs) and preformed zirconia crowns (ZCs). METHODS: Forty-eight molar incisor hypomineralisation (MIH)- or caries-affected permanent molars in 20 healthy patients between 6-13-year-old were randomly divided into ZC and SSC groups (n = 24 teeth/group) in a split-mouth design. The oral hygiene levels of patients were assessed using Greene and Vermillion simplified oral hygiene index (OHI-S). Plaque accumulation and gingival health were evaluated using the Silness&Löe plaque index (PI) and Löe&Silness gingival index (GI), respectively. Clinical retention, marginal extension level, marginal adaptation of crowns and wear of the antagonist teeth were assessed at baseline, 1, 6, 12 and 18 months. The radiological assessments for evaluating the marginal adaptation of crowns and periapical pathology of crowned teeth were performed at 6 and 12 months. The data were analyzed using Kaplan-Meier analysis, Mann-Whitney U test, and two-way ANOVA. RESULTS: A total of forty teeth in 17 children were evaluated for 18 months. ZCs had significantly lower gingival and plaque index values than teeth restored with SSCs during all evaluation periods (p < 0.05). Neither crown type resulted in clinically-detectable wear on opposing dentition or periapical pathology. One ZC was lost at 13 months, while all SSCs survived in function clinically. The cumulative survival rates of ZCs and SSCs were 95.2% and 100% respectively. CONCLUSIONS: Both ZCs and SSCs showed high clinical retention rates in young permanent molars. ZCs had lower plaque accumulation and better gingival health than SSCs, which were consistently associated with mild gingival inflammation. CLINICAL TRIAL REGISTRATION NUMBER: NCT05049694.

Clinical Comparison of Preformed Zirconia and Composite Strip Crowns in Primary Maxillary Incisors: 18-Month Results of a Prospective, Randomized Trial.

Purpose: The purpose of this study was to evaluate the clinical performance of composite strip crowns (SCs) and zirconia crowns (ZCs) on primary maxillary incisors affected by early childhood caries over 18 months. Methods: A total of 111 primary maxillary anterior teeth were included in 25 three-to five-year-old children. In each patient, the teeth were randomized to the SC and ZC groups (n equals 43 teeth/group) and sound teeth as the control group (n equals 25) in a split-mouth design. Patients' oral hygiene and clinical variables, including gingival health, plaque accumulation, pulpal health, secondary caries, retention, color match, and material loss, were assessed at baseline and at one, six, 12, and 18 months. Data were statistically analyzed using Fisher's exact test, the Friedman test, and the Kruskal-Wallis test. Results: Zirconia crowns had significantly lower plaque index values than strip crowns and controls during all recalls (P<0.05). The gingival index scores of both crowns improved after six months, while mild inflammation persisted in both groups due to increased exfoliation mobility. ZCs had better color match and retention (P<0.05) than SCs, with the latter being 100 percent for ZCs and 77.8 percent for SCs. Both crowns had similar and high pulp survival at 18 months (ZC equals 93.1 percent; SC equals 95.4 percent). Conclusions: Zirconia crowns had better clinical performance than composite strip crowns in terms of retention, restoration failure, and color change but similar gingival and pulpal health after 18 months. ZCs showed the lowest plaque accumulation when compared with sound teeth and SCs.