Identification of multi-dimensional thread geometry using depth-resolved swept-source optical coherence tomography for assessment of dental implant fabrication

The geometrical characteristics of dental implants, such as thread depth and width, facing angle, pitch, and surface roughness, are important to assess their stability and osseointegration after implant surgery. Herein, we demonstrate the potential use of depth-resolved swept-source optical coherence tomography (SS-OCT) to assess the structural quality of widely used dental implants. The implemented SS-OCT system was centered at a wavelength of 1300 nm with a 100 nm full-width at half-maximum. Four dental implants with different structural formations fabricated using either titanium or ceramic were visualized. Qualitative assessments were performed using boundary flattening with an amplitude-profiling algorithm to emphasize and compare the thread depths, surface roughness, and inner structures of the experimental samples. Cross-sectional and volumetric OCT data clearly revealed the depth, width, and pitch of the dental implants, and especially, the quantitative assessment of axial and lateral thread depth unobtainable using conventional inspection methods was successfully conducted. The depth of thread was measured using a depth-directional intensity profile. In conclusion, the high-resolution SS-OCT system could be utilized to improve the quality assurance of dental implant products through multi-plane assessment.