Image-guided removal of occlusal caries lesions with a λ= 9.3-µm CO₂ laser using near-IR transillumination

Previous studies have shown that near-IR transillumination is well suited for imaging deep occlusal lesions. The purpose of this study was to determine if near-IR images can be used to guide a CO₂ laser for the selective removal of natural occlusal lesions on extracted teeth. Near-IR occlusal transillumination images of extracted human teeth with natural occlusal caries lesions were acquired using an InGaAs camera and near-IR light at wavelengths from 1290 to 1470-nm from a filtered tungsten halogen source. A CO₂ laser operating at 9.3-µm with a pulse duration of 10-15-µs and a pulse repetition rate of 100-300-Hz was used for caries removal. Optical Coherence tomography was used to confirm lesion presence and serial scans were used to assess selective removal. Teeth were also sectioned for histological examination using polarized light microscopy. This study suggests that near-infrared transillumination is a promising method for the image guided laser ablation of occlusal caries lesions but the use of serial near-IR transillumination imaging for monitoring lesion removal was limited.