Comparison and evaluation of the morphology of crowns generated by biogeneric design technique with CEREC chairside system.

OBJECTIVES: To better guide clinicians to choose the appropriate chairside system, we compared and evaluated the morphology of crowns generated by three different biogeneric design modes (biogeneric copy (BC), biogeneric individual (BI), and biogeneric reference (BR)) of the CEREC software. METHODS: Maxillary and mandibular casts were obtained from twelve volunteers and digital impressions were acquired. All ceramic crown preparations of all right maxillary central incisors were prepared and digital impressions were taken. Then, crowns were automatically designed under BC, BI and BR modes separately and their morphologies were evaluated by six doctors. The "optimal fitting alignment" and "3D analysis" functions of the Geomagic Qualify software were carried out between original teeth and auto-generated full crowns. The auto-generated crowns were modified by a technician according to clinical criteria and the adjustment time was recorded. The discrepancies between technician modified crowns and the auto-generated full crowns were evaluated with the same functions in the Geomagic Qualify software. RESULTS: The subjective evaluation results of BC group were significantly better than those of BI and BR group (p < 0.05). Compared with the original teeth and modified crowns, auto-generated crowns in BC group all had the smallest differences, followed by BR and BI group (p < 0.05). BC group needed the shortest adjustment time than BI and BR group (p < 0.05). CONCLUSIONS: Using crowns generated by BC mode is more aesthetic and suitable in clinics use than those generated by BI and BR modes and can reduce clinic adjustment time.