A comparison of differences of some aesthetic criteria between highly translucent zirconia crowns and IPS-Emax crowns on maxillary premolars

Abstract

Background and Aim of study: Any discrepancies in the anterior maxillary teeth can greatly affect the aesthetic outcomes; these teeth can be treated with several prosthodontic options such as full ceramic crowns and ceramic veneers. For many years, the treatment of choice has been full ceramic crowns. But this is a non-conservative method that requires the removal of large portions of the prosthodontic bearing teeth to achieve certain criteria needed for some ceramic materials. The amount of preserved dental tissue achieved when using Lava Plus led to the design of this study.

Materials and Methods: The specimen consists of 60 full ceramic crowns divided in two groups; group one consists of 30 full ceramic crowns – translucent zirconia from 3M Lava Plus Zirconia, manufactured using CAD/CAM technology. Group two consists of 30 full ceramic crowns – IPS E-Max from Ivocal Vivadent manufactured using CAD/CAM technology. These clinical cases were evaluated regularly after one week, three months, six months, and one year after crown adhesion. And were corrected by three dentists independently from the researcher and without knowing the materials used in the manufacturing of the crowns after being trained to conduct proper evaluation. Making this a double blinded study. The materials used in the manufacturing of crowns were unknown to the patients and control committee. The Mann-whitney U test was used to assess differences of aesthetic outcomes between the two groups (Lava plus CAD, IPS E-max CAD) during the evaluation period.

Results: All ceramic crowns had a gloss resembling that of enamel one week after adhesion. 15% of crowns in the high translucent zirconia group and 3% of crowns in the IPS-Emax group had a loss of gloss and became dull 3 months, 6 months, and 12 months after adhesion. No cases in both groups had any score on the surface pigmentation index and marginal pigmentation index..

Conclusions: Within the parameters of this study we conclude that there are evident clinical differences between the two groups regarding the relevant aesthetic criteria. The zirconia crowns are superior in retaining gloss during the evaluation period.