Zirconia CAD-CAM Crowns Behavior after Intraoral Digital Impression in Normal versus Dysfunctional Patients: 3 Years Retrospective Study

Abstract

Objectives: The aim of this study was to evaluate the clinical performance and possible complications of single zirconia crowns fabricated using an intraoral digital computer-aided design-computer-aided manufacturing (CAD-CAM) protocol in normal and dysfunctional patients after 3 years of follow-up.

Materials and methods: Seventy patients were included in this study. The teeth were prepared with a knife-edge marginal design, and temporary crowns were placed. Digital impressions were taken using optical scanning, and the frameworks were milled using the same technology. The veneering process was performed by the same dental technician. The occlusal corrections were made before cementation. The outcomes were evaluated in terms of survival, failures, and complications. The marginal adaptation of the crowns was also assessed.

Results: The digital protocol for single zirconia crowns resulted in satisfactory outcomes, with high rates of survival and minimal complications after 3 years of follow-up. The marginal adaptation of the crowns was excellent, with 93% of the restorations achieving the ideal marginal adaptation, while 7% had minor deviations. Parafunctions were found in 41.9% of the prosthetic rehabilitation, but no significant differences were observed between the normal and dysfunctional groups regarding the survival and complications of the crowns.

Conclusion: The digital protocol for single zirconia crowns is a reliable and predictable treatment option, even for patients with parafunction, when proper occlusal corrections are performed before cementation. The use of intraoral digital CAD-CAM technologies with optical impressions can simplify procedures, reduce the workflow time, and minimize the variables linked to the human factor.

Fig. 1

Element structurally compromised and treated endodontically. Prosthetic rehabilitation with crown is required.

Fig. 2

Element prepared with a knife-edge finishing line. Periodontal tissues conditioned by the provisional during optical impression taking.

Fig. 3

Definitive crown delivery.

Fig. 4

Evaluation of the precision of the finishing margin on the model at 40x magnification under an optical microscope.

Fig. 5

Chipping of the distal–palatal cusp of a tooth 1.6.

Fig. 6

Fracture of the distal–lingual shear cusp of a tooth 4.6.

Fig. 7

Distribution of complications in parafunctional and nonparafunctional patients.