One-Year Controlled Clinical Study Status Report: BruxZir and IPS e.maxCAD
A one-year status report on a controlled clinical study now in progress at TRAC Research on three full-contour study materials is posting very positive results. The study includes BruxZir full-contour zirconia and IPS e.maxCAD full-contour lithium disilicate, both fabricated in the laboratory by Glidewell Laboratories, IPS e.maxCAD milled chairside by a group of dentists who are CEREC® experts, and the study control, which is Metoxit zirconia with Swiss NF Metal’s PressCeram veneer ceramic fabricated by Burbank Laboratory. After one year of clinical service, none of the three test materials showed serious problems. In fact, scanning electron microscope images showed the test materials were in excellent condition. The control material showed problems typical of today’s weak veneer ceramics.
Twenty-two dentists from 13 US states are participating in the study. The Sirona AC Bluecam digital intraoral impression scanner was used to transmit design data via CEREC Connect 3.65 to the laboratories for milling single-unit crowns for molars. The first goal of the study was to determine if any differences existed in the success rate of IPS e.maxCAD full-contour restorations fabricated chairside by the dentists using a fast-mill/fast-fire protocol developed by Dr. Paul Child, and those produced by the laboratory using the protocol set forth by Ivoclar Vivadent. The second goal of the study was to compare the clinical durability of single-unit full crowns overlayed with veneer ceramic versus the new monolithic materials. The final goal was to monitor wear on opposing dentition by the crowns and vice versa.
“Right now, although the monolithic crowns themselves are showing the most promising results we have seen at one year compared to over 100 different tooth-colored materials we have followed in controlled clinical trials in the past 35 years, we are keeping a close eye on their wear of opposing dentition,” said Dr. Rella Christensen, lead scientist at TRAC Research. “Right now, all materials in the study and their opposing dentition show small wear facets. However, statistically, wear facets opposing the glazed BruxZir crowns are more numerous and larger. We need more clinical service time to see if this trend persists or if it is just initial wear that will stabilize. At the end of the first year, these restorations look excellent and we have high expectations for the future of the monolithic materials. As we continue this study, we will release status reports frequently to keep laboratories, dentists, and patients informed.”
The below four sets of scanning electron microscope images show representative example cases of BruxZir, e.maxCAD, and the PressCeram study control at initial placement (A) and after one year of service in the oral cavity (B). Careful monitoring of both arches shows normal small wear facets developing on both the test crowns and the full range of materials and enamel that comprise opposing dentitions.