Development of a Raman probe for non-invasive molecular assessment of alveolar bone graft integration

Alveolar ridge preservation relies heavily on bone grafting materials, yet clinicians currently lack a non-invasive method to determine whether graft particles have successfully integrated into host bone. Radiographic techniques such as X-ray and CBCT cannot distinguish mineralised graft granules from regenerating bone, always necessitating surgical re-entry. This project aims to address this critical clinical gap by developing a transmission Raman–based optical system capable of depth-resolved, molecular-specific assessment of alveolar bone regeneration. A comprehensive reference spectral library of graft materials and bone was first established, and controlled demineralisation and deproteinization experiments confirmed that Raman spectroscopy sensitively differentiates mineral and organic components. Soft-tissue phantoms demonstrated that conventional backscattering Raman is limited to ~1.2 mm penetration, failing to detect subsurface bone beneath gingiva. In contrast, multilayer “sandwich” phantoms showed that transmission Raman can detect hydroxyapatite signals through up to 1.5 mm soft tissue and several millimetres of bone, enabling bulk sampling from clinically relevant depths. A compact 3D-printed transmission Raman probe was then designed using a CAD–CAM workflow integrating collimators, filters, lenses, and fibre optics. The prototype produced high-fidelity spectra from polystyrene and human tooth samples, confirming optical alignment, mechanical stability, and functional feasibility. These findings collectively establish the technical foundation for a miniaturised intraoral Raman device. This work provides the first integrated demonstration that transmission Raman can overcome soft-tissue attenuation and enable non-invasive molecular monitoring of graft-to-bone transformation, paving the way for probe optimisation, quantitative modelling, and forthcoming pre-clinical and in vivo validation.