Clinical Trial of OCT Imaging of Posterior Adhesive Ceramic Restorations

Objectives: In vitro studies have proven that swept source Optical Coherence Tomography (ssOCT) is an extraordinary tool for 3D evaluation of structural integrity and marginal adaptation, detection and quantification of cracks, and interfacial gaps (IG) in adhesive ceramic restorations. This study evaluated the clinical use of ssOCT.
Methods: A clinical trial assessed the clinical performance of a dental adhesive (Adhese Universal, IvoclarVivadent) and dual-curing composite resin cement (Variolink Esthetic) for cementation of 50 posterior CAD/CAM lithium disilicate ceramic restorations. Ceramic onlay preparations were designed with a hollow-ground bevel margin on Non-Supporting Cusps (NSC) and a shoulder margin design on Supporting Cusps (SPC). A completely digital protocol was followed for optical impressions (Trios, 3Shape); virtual model/onlay design (dental design, 3Shape), e.maxCAD milled (Wieland)(all performed virtually with no dies/models); stained/glazed. Then delivery, adjustment, cementation. Imaging with an ssOCT device (Yoshida Dental OCT, Japan) was added to the 6-12 month recall protocol. A standardized protocol for measuring vertical marginal discrepancy (VMD) and horizontal marginal discrepancy (HMD) was followed (Sorensen. J Prosth Dent 1990;64:18-24) with 6 measurement points on both buccal and lingual aspects, and length of IG were recorded. Summary statistics and comparisons were made with nonparametric statistics, MannWhitneyU and Spearman’s correlation.
Results: Twelve onlays were imaged and analyzed (Amira®software). Mean(sd) VMD: NSC=53±104um, Zero Marginal Discrepancy (ZMD)=70%; SPC=72±118um, ZMD=69%. Mean(sd) HMD: NSC=54±76um, ZMD=59%; SPC=94±98um, ZMD=41%. Mean(sd) IG length: NSC=160±344um, Zero IG (ZIG)=71%; SPC=402±963um, ZIG=39%. MannWhitneyU test demonstrated a significant difference in HMD and interfacial gaps between SPC and NSC (p<0.05) but not VMD. For ZIG, significant difference existed between NSC and SPC (p<0.01). Spearman's correlation suggested both VMD (p<0.05) and HMD (p<0.01) discrepancies were significantly correlated with IG.
Conclusions: The only limitation to ssOCT scanning was when margins were located subgingivally.
ssOCT technology provides a powerful tool for in-depth 3D clinical assessment of adhesive ceramic restoration marginal fidelity and interfacial gaps.