Volumetric misfit in CAD/CAM and cast implant frameworks: a university laboratory study.

PURPOSE

To compare the volumetric misfit between implant restorative platforms of implants and implant frameworks manufactured with two different technologies. One set of implant frameworks was made with a CAD/CAM protocol and a tactile probe; the second protocol consisted of frameworks made with the lost-wax technique and conventional casting technology.

MATERIALS AND METHODS

In this laboratory study, an acrylic resin model with five "inter-foraminal" implants was used as the "patient" model. Implant level impressions were made, and 10 definitive master casts were fabricated. The casts were verified using an index made on the patient model. Five cast high palladium noble alloy and five CAD/CAM titanium alloy frameworks were fabricated. The patient's implants and the frameworks' implant restorative platforms were scanned with a tactile probe, and the data were digitized. The digitized implant restorative platforms of the frameworks were fit onto the patient's digitized implants via a software program, in a process called "lofting." This computerized procedure simulated a 1-screw test; the process was performed on both sides. The volumetric misfit between the implant restorative platforms of the frameworks and the patient's implants were measured. A Welch's t-test was used to determine significant differences (p < 0.05) between the misfit of the two technologies. Wilcoxon Signed-Rank tests were used to evaluate differences between the right and left sides.

RESULTS

On average, the volumetric misfit of the CAD/CAM frameworks was 1.8 mm(3) less than the volumetric misfit of the cast alloy frameworks (p < 0.05). The Wilcoxon Signed-Rank tests showed no significant differences between the right and left sides within both systems (p > 0.05).

CONCLUSIONS

The scanning technology and computer software program used in this study demonstrated that the CAD/CAM implant frameworks had statistically significantly less volumetric misfit when compared with the cast implant frameworks. There were no significant differences between the right and left 1-screw tests within the same type of frameworks.