Preformed pediatric zirconia crown versus preformed pediatric metal crown: study protocol for a randomized clinical trial.

BACKGROUND: Guidelines in pediatric restorative dentistry recommend the use of preformed pediatric stainless steel crowns (SSCs) in cases of severe tooth decay of at least two surfaces. This clinically effective and safe restorative option is frequently refused by parents for esthetic reasons; they prefer conventional restorations using esthetic filling materials (composites, glass ionomer) if lesion severity limited to two surfaces permits. Recently, manufacturers have proposed esthetic preformed pediatric zirconia crowns (ZCs) but these have been assessed in only two randomized clinical trials (RCT) with follow-ups of 6 and 12 months. Only one of these RCTs was carried out on primary molars to test ZCs (NuSmile ZR) without a groove in its inner surface. The primary objective of this proposed RCT is to assess the effectiveness of ZCs compared with SSCs. Our hypothesis is that the effectiveness of ZCs will be equivalent to that of SSCs.

METHODS: In this split-mouth, 2-year RCT, pairs of primary molars in 101 child participants will be randomized and restored with SSCs (ESPE, 3M) and ZCs (EZCrowns, Sprig Oral Health Technologies) characterized by grooves on their inner surface. Primary molars will first be allocated to SSCs, and 1 to 2 weeks later the other primary molar of the same pair will be restored by ZC. The primary outcome is the success defined by the "absence of major clinical and radiographic failure" (e.g., pain, pulp infection, dental abscess or periradicular pathology visible on radiographs). The secondary outcomes include the retention and fracture rates, the gingival condition, the wear of the antagonist of the treated teeth, as well as both parental and child satisfaction.

DISCUSSION: This study will investigate two types of preformed pediatric crowns for the management of severe decay on primary molars. The results may help practitioners choose the better therapeutic option and to explain to parents the advantages and disadvantages of these two therapies.

TRIAL REGISTRATION: NCT03296709 . Registered on  27 September 2017.