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

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. 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. 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). 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.