Long-term Clinical Performance of Prefabricated Zirconia Crowns in the Primary Dentition

Objectives: This study prospectively evaluated children who had received zirconia full coverage restorations in their primary teeth due to caries or developmental defects.
Methods: Consecutive patients were evaluated at 4 monthly intervals following restoration with zirconia crowns. Survival of the crowns was the primary outcome, however gingival response, occlusal changes and wear of opposing dentition was also monitored using clinical, radiographic and photographic evaluation by a single operator.
Results: 22 patients were reviewed. There were 13 girls and 9 boys with a total of 94 crowns (28 upper incisors, 16 canines, 30 first primary molars, 16 second primary molars and 4 lower incisors). Seven patients with 17 crowns have over 36 months follow up and 15 patients (77 crowns) were followed over 24 months. Four upper incisor crowns, one canine crown and one first molar crown were dislodged by trauma, all were replaced but two crowns subsequently were not retained. In addition, one primary molar crown partially fractured , did not debond or require further treatment. A successful outcome was recorded therefore in 97% crowns placed. No adverse pulpal, gingival or occlusal changes were noted and wear on opposing teeth was minimal. Two teeth were extracted prematurely to manage ectopic eruption of a permanent mola r and incisor. Crowns on these teeth were not considered clinical failures.
Conclusions: This study demonstrates that zirconia crowns are durable over 2-3 years and can compete with SSC and strip crowns for longevity and clinical performance. Traumatic injury was the main factor for crown loss and replacement crown did not require further tooth preparation.