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Updated: Sep 2, 2026
Real-Time Imaging of Bonding in 3D-Printed Layers
Published on: September 1, 2023
Non-Destructive Assessment of Dentin Composite Bond Integrity using Laser Speckle Imaging and Machine Learning
Doaa Youssef1, Doaa M Sadony2, Mona A Sabry3
1Engineering Applications of Lasers Department, National Institute for Laser Enhanced Sciences, Cairo University, Giza, Egypt. doaaysf@niles.edu.eg.
Purpose:
Accurate evaluation of dentin-composite bond integrity is essential for predicting the longevity of resin-based restorations. However, conventional mechanical testing methods are destructive and do not provide a non-destructive means of assessing early interfacial changes. Owing to the complex microstructure and heterogeneous composition of dentin, reliable non-destructive assessment remains challenging. This study proposes a novel optical-machine learning framework based on laser speckle imaging for non-destructive assessment of dentin-composite interfacial bond integrity.
Methods:
Different bonding protocols involving an Au NP-modified adhesive system and laser irradiation at controlled stages of the bonding procedure were investigated to produce variations in the dentin-composite interfacial conditions. Speckle patterns were collected from the bonded interface using a 632 nm He-Ne laser and morphologically processed to extract statistical features characterizing interfacial heterogeneity. Permutation-based feature importance ranking was applied using a random forest (RF) model. The top seven ranked features were subsequently used to train support vector regression (SVR) and RF models using specimen-level measurements of shear bond strength as the reference outcome.
Results:
SVR achieved a calibration coefficient of determination (R2) of 0.914 and a test RMSE of 0.234 MPa, while RF achieved a calibration R2 of 0.919 and a test RMSE of 0.228 MPa. Both models showed strong agreement between predicted and mechanically measured shear bond strength values.
Conclusion:
Morphological laser speckle descriptors provide a promising non-destructive approach for characterizing dentin-composite interface heterogeneity under controlled in vitro conditions, supporting the potential feasibility of laser speckle imaging as an optical predictive tool for interfacial bond integrity assessment. These encourgaing results support further investigation of the proposed approach under clinically relevant conditions.
