401 - Effect of Incisal Height on Anterior Zirconia Crown Retention of Primary Maxillary Central Incisors

Purpose: This study aimed to test the effects of incisal height of primary maxillary incisors on retention of anterior prefabricated zirconia crowns.

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Methods: Sixty tooth preparations were designed by using the negative of a NuSmile® brand primary prefabricated anterior zirconia crown and created using 3D-printed die resin. These preparations were divided into groups of 10 beginning with the ideal inciso-cervical height of 5.0 mm. The inciso-cervical heights of each remaining group of 10 were reduced in increments of 0.75 mm (5.0 mm, 4.25 mm, 3.50 mm, 2.75 mm, 2.00, 1.25 mm). Sixty NuSmile® brand zirconia crowns were cemented to the 3D tooth preparations using 3M RelyX™ Luting Plus Automix. All groups were placed in an incubator at 37-degree Celsius for twenty-four hours and pulloff tests using the Instron 5566 were completed. Statistical analysis using Pairwise Wilcoxon rank-sum tests was used to compare the force and megapascals among inciso-cervical height groups.

Results: Preparations with inciso-cervical heights ≥ 3.5mm showed statistically significant greater tensile stress compared to shorter heights.

Conclusion: The findings indicate that increased inciso-cervical height increased the retention of primary anterior prefabricated zirconia crowns..

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