Title: 0253 - 3D Real-time Monitoring of Adhesive Ceramic Cementation Phenomenon Using ssOCT
John Sorensen (Presenter)
University of Washington
Alireza Sadr, University of Washington School of Dentistry
Objectives: The high C-Factor of resin composite cements for adhesive ceramics generate extraordinary polymerization shrinkage stresses that test the bond to dentin substrates. This study evaluated different cementation polymerization scenarios, photopolymerized and autopolymerized, for adhesive ceramics in real-time 3D using swept-source Optical Coherence Tomography (ssOCT) during cementation.
Methods: Human molars were ground flat (600-grit) exposing dentin and enamel periphery. Lithium-disilicate (e.max, Ivoclar-Vivadent) flattop onlays 1.0 mm thick were milled and sintered. Onlays: HF-etched and MonoBond-Plus applied. Enamel: phosphoric acid-etched 40 sec. No dentin-adhesive was applied. Variolink Esthetic Cement-DC (Ivoclar-Vivadent) was applied, onlay seated, positioned on ssOCT (Yoshida, Japan) stage, and pressure maintained during excess cement removal and photopolymerization. Utilizing ssOCT 1300 nm center wavelength, specimens were scanned every 30 seconds. Group-1: Photopolymerized for 1 min at occlusal, buccal, lingual aspects. Group-2: Autopolymerized mode initial 2 minutes then photopolymerized as Group-1. Times compared: 0,120,300 seconds. Amira® software used to visualize/quantify interfacial gaps. A novel variable was calculated from 3D images: Total Gap Percentage (TGP)=Sum of Area of all Interfacial Gaps/Total Cementation Substrate Area x 100.
Results: Dentin-cement interfacial (DCI) gaps formed initially towards middle growing larger, sometimes several gaps merging, spreading to tooth center. With n=5 per group, Mean(SD) TGP at 0,120,300 seconds- Group 1: 29.3(8.3); 30.8(8.5); 32.2(9.2). Group 2: 17.1(4.4); 18.1(4.3); 26.7(8.2). Repeated Measures ANOVA showed overall, time was a significant factor, indicating growth of TGP over time (p<0.05). In first 2 minutes of polymerization, there was a significant difference between groups (p<0.05). However, t-test at 300 seconds, indicated no difference in final gap formation between groups (p>0.05).
Conclusions: While the TGP at the dentin-cement interface was significantly different at the initial 2 minute autopolymerized mode, after photopolymerization no difference existed between groups. OCT is a powerful tool for 3D detection, real-time dynamic visualization and quantification of interfacial gaps in cemented ceramic restorations.
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: None