Monolithic lithium-disilicate single crowns supported by zirconia oral implants: three-year results of a prospective cohort study.
OBJECTIVE
To determine the survival and success rate of CAD/CAM-fabricated monolithic lithium-disilicate crowns supported by zirconia oral implants after 3 years.


METHODS
Twenty-four patients in need of a single tooth replacement received a zirconia implant and were finally restored with 24 single crowns (SCs) ground out of pre-crystallized lithium-disilicate blanks. The restorations were adhesively cemented and evaluated using modified United States Public Health Service (USPHS) criteria. In case of clinically relevant defects that could be repaired to an acceptable level, SCs were regarded as surviving. Restorations with minor chippings, a small-area roughness (ø <2 mm), slightly soundable marginal gaps, minimal under-/overcontours, and tolerable color deviations (<1 Vitashade) were regarded as success. The Kaplan-Meier method and log-rank tests were used for the success/survival analyses and the calculation of potential group differences (gender, location, jaw). Additionally, several patient-reported outcome measures (PROMs) were evaluated.


RESULTS
Twenty-three patients were seen 3 years after implant placement. No SC had to be replaced, resulting in 100% survival. No chippings were observed. As one SC showed a major occlusal roughness, the Kaplan-Meier success rate after a mean observation period of 31 months was 95.7%. No group differences could be calculated. Compared with the pre-treatment surveys, the further PROMs showed a permanently improved perception of function, esthetics, sense, and speech.


CONCLUSIONS
Monolithic lithium-disilicate SCs supported by zirconia implants showed promising survival and success rates after an observation period of 3 years. It remains to be seen whether the further observation period confirms this positive results.
Center for Dental Medicine, Department of Prosthetic Dentistry, Medical Center - University of Freiburg, Freiburg, Germany.
Benedikt Christopher
BC
Spies
Center for Dental Medicine, Department of Prosthetic Dentistry, Medical Center - University of Freiburg, Freiburg, Germany.
Sebastian Berthold Maximilian
SB
Patzelt
Center for Medical Biometry and Medical Informatics, Institute for Medical Biometry and Statistics, Medical Center - University of Freiburg, Freiburg, Germany.
Kirstin
K
Vach
Center for Dental Medicine, Department of Prosthetic Dentistry, Medical Center - University of Freiburg, Freiburg, Germany.
Ralf-Joachim
RJ
Kohal
D000328:Adult; D017076:Computer-Aided Design; D003442:Crowns; D003776:Dental Porcelain; D017267:Dental Prosthesis Design / Q000379:methods; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D055815:Young Adult; D015040:Zirconium
C493120:lithia disilicate; D003776:Dental Porcelain; D015040:Zirconium; C028541:zirconium oxide
ceramics; cohort study; computer-aided design - computer-assisted manufacturing; crown; dental implant; dental porcelain; lithium disilicate; zirconia