Ultrasonic Imaging of Bone Graft Healing in Extraction Sockets for Precise and Personalized Implant Therapy

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Abstract Socket augmentation after tooth extraction by placing either allograft or xenograft bone particulates in the socket is frequently applied to reduce the jawbone volume shrinkage for subsequent implant placement. Socket healing after augmentation varies largely, ranging from uneventful healing to infection, failure of bone graft integration and severe bone loss due to bacterial infection and/or local/systemic conditions. The healing duration, which dictates the timing of implant placement, is widely different as well. Currently, an arbitrary waiting time of 6 months after socket augmentation is adopted, when a 2-dimensional (2-D) or 3-D radiograph, along with a visual examination is performed to assess hard- and soft-tissue healing to determine the readiness and strategy for implant surgery. However, 3-D radiographs are not recommended for longitudinal use to monitor socket healing due to radiation concerns. They have low image resolution (250-500 µm), which limits their ability to evaluate bone surface healing, and have inferior soft-tissue contrast. A non-radiation and point-of-care method that can evaluate both hard- and soft-tissue longitudinally is much needed for a definitive, accurate, and timely diagnosis of socket healing pathologies. A high-frequency and miniature-sized intraoral ultrasound probe that can operate on an off-the-shelf scanner has been manufactured in collaboration with industry by our research team. Research conducted by our group demonstrated accuracy of this probe in measuring various oral and dental structures. The central hypothesis is to develop ultrasound-based imaging to characterize and grade socket healing lesions in determining their extent and severity. To test this hypothesis, two aims are proposed in this proposal. Aim 1. Evaluate the diagnostic value of ultrasound images for bone grafting procedures of dental extraction sockets in a longitudinal clinical study (from -2 months to +6 months of graft placement). We will compare other imaging and clinical diagnostic tools for assessing hard- and soft-tissue, anatomical and physiological status throughout the longitudinal study time- course. Aim 2. Develop a concave extended-view transducer array for acquiring large view-angle jawbone images and determine buccal to lingual tissue morphology. We will engage the manufacturer to create an extended aperture transducer for this specific dental application. Design goals will include the creation of an extended, large angle, field-of-view to visualize the buccal to lingual jawbone surface. We will also further our existing machine learning (ML) based measurement tools, including soft- and hard-tissue dimensions and crestal bone surface analysis to yield an ultrasound-based bone quality classification system. Successful execution of the proposed aims will result in a clinical tool for longitudinal socket augmentation evaluation that is based on ultrasound soft- and hard-tissue features and will allow the care provider to choose deviations from current clinical procedures where indicated. Those would be investigated subsequently in a specifically designed clinical trial.