Diagnostic Accuracy of OCT to Detect Secondary Caries Beneath Ceramics

Objectives: Optical coherence tomography (OCT) is a well-established diagnostic tool in ophthalmology, allowing for non-ionising, cross-sectional, non-invasive imaging at a resolution of approximately 10µm. Recently, studies have shown OCT to be useful for detection of caries and tooth demineralization. The aim of this study was to evaluate the diagnostic accuracy of a modified ophthalmic OCT device for the detection of secondary caries beneath ceramic materials.
Methods: Discs made of four widely used ceramic materials (hybrid ceramic, feldspathic ceramic, zirconia-reinforced lithium silicate, and lithium disilicate) were produced. The discs were ground to the minimum material thickness recommended by the manufacturers, and laminated with a 100µm thick layer of one of three adhesive cements (Panavia 21, Variolink Esthetic and RelyX Unicem). These materials were fixed on flattened extracted human molars with or without carious lesions. The lesions were standardized as codes 2 to 4 cavities (International Caries Detection and Assessment System). A total of 192 stacks of cross-sectional OCT-scans was presented to five examiners in random order, after a calibration session. Diagnostic accuracy was determined by rating the teeth beneath the material and cement as carious or healthy.
Results: The samples with lesions were identified from those without lesions with high diagnostic accuracy: sensitivity/specificity (SE/SP) values pooled over all examiners and all materials were 0.87/0.96. When analyzing the influence of ceramic materials and cement type, lithium silicate and zirconia-reinforced lithium silicate showed high SE/SP values (>0.96/>0.91), irrespective of the cement type. While high SE/SP were also detected for hybrid and feldspathic ceramics in combination with Variolink Esthetic, there were particular problems in combination with Panavia 21.
Conclusions: Given its high resolution, OCT could be a valuable diagnostic tool for the detection of dental decay under ceramic restorations.