Prospective randomized clinical trial of primary molar crowns: 36-month results

To clinically evaluate the clinical success of a primary zirconia molar crown, compared with stainless steel crowns (SSCs).

This randomized, controlled clinical trial was designed as a split-mouth study. 50 subjects ranging in age from 3-7 years were recruited to provide a total of 50 paired teeth requiring primary molar crowns, each participant receiving a SSC and zirconia crown. Restorations were evaluated at 6-, 12-, 24-, and 36-month recall appointments examining the following criteria: gingival health, estimate of the degree crown was high in occlusion, surface roughness, staining on crown surface, wear of opposing arch tooth, color match, anatomic form, marginal integrity, marginal discoloration, proximal contact area, secondary caries at crown margin and parent/guardian satisfaction with crown appearance.

The 36-month follow up included 23 subjects (46%). 35 crowns (35%) were evaluated; of the 18 zirconia crowns and 17 SSCs, there were no failures at the 36-month evaluation. The only significant differences in the parameters evaluated were parent satisfaction, with the zirconia crown preference (P< 0.05) and gingival health, with the zirconia crowns having healthy adjacent gingiva (P< 0.01). The 36-month results indicated that zirconia primary molar crowns performed similarly to an established SSC for restoration of primary molars.

The findings from this study indicated that at 36 months, NuSmile ZR zirconia crowns clinically performed as well as stainless steel crowns.