Method: Total of 338 CAD/CAM custom zirconia abutments for cement-retained implant crowns and bridges were included. Group I included 181 zirconia abutments with a zirconia circumference and a friction fit metal component at the implant mating surface (Procera, Nobelbiocare). Group II included 157 abutments made of zirconia entirely (Atlantis, Dentsply). Abutments were fabricated 2 to 8 years prior to data collection in a dental laboratory in the USA. Data collected included tooth number, time from delivery, abutment brand, connection type, and causes for remakes. Probability distributions of remakes and Chi-squared test (with Yates’ correction) for intergroup comparison were used.
Result: Out of 338 abutments included, 274 were anterior (incisors, canines) and 64 posterior (premolars, molars). With a mean 6-year follow-up, 12 abutments required replacement, resulting in 3.6% over all remake rates. Both groups exhibited comparable remake rates (Group I 2.7%, Group II 4.5%) (p=0.74). 9 abutments were anterior (3.3% remake rate), and 3 were posterior (4.7% remake rate) with the anterior area having significantly less remakes than the posterior area (p<0.01). 9 abutments were sent for remake at time of insertion (2.7%) and 3 were remade within 12 to 24 months of service (0.9%). Remake rate after delivery was significantly lower than that at time of insertion (p<0.01). Causes (number of abutments, percentage) were abutment fracture (3, 0.89%), design issues (5, 1.47%), gingival recession (3, 0.89%), and misplacement (1, 0.30%).
Conclusion: Within the limitations of this retrospective laboratory survey, it may be concluded that frequency of remakes of zirconia abutments made by a dental laboratory was low at mean 6 years of service.