OCT and RX validation of metal-ceramic crowns repaired with ceramic material

Objective: Study's objectives are focused on non-invasive OCT and RX investigations, of interfaces obtained after repairing a metal-ceramic crown with ceramic materials. Material and method: In this study 40 metal-ceramic crowns were involved. Each crown is restoring the first central incisor 1.1. Metallic infrastructure was performed from nickel-chrome WIRON 99 BEGO alloy, and Kiss Ceramic. The defects of 3×3mm were created into ceramic material in the buccal-incisal area with a grinding instrument. The samples were divided into two groups and the defects were reconstructed with two different types of ceramic materials: Kiss and Vita Omega. The interfaces between crown and ceramic material used for reparation were Rx and OCT investigated which are both non-invasive, imagistic investigation techniques. For better investigation three-dimensional reconstructions were performed. Results: The interfaces showed defects for both systems used. Major defects such as gaps could be identified at the ceramic-ceramic interface. Also material defects could be observed at the areas of congruence between the two ceramic materials and smaller defects along the interfaces. The defects were present into the deep and superficial layers of interface. The OCT system used a length wave of 1300nm and worked in B-scan mode along the interfaces to be studied while the C-scan mode was only used at the defect areas. Rx investigation detected the macro defects. Conclusions: Time Domain OCT and RX systems were identifying the faulty areas after repairing artificially created defects, of metal-ceramic crowns with ceramic material, hereby enabling us to establish recommendations for the clinical use.