Deformation measurements in cortical bone-miniscrew interface in human maxilla by using digital speckle pattern interferometry

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An application of digital speckle pattern interferometry (DSPI) is demonstrated for the measurement of out-of-plane and in-plane deformations in the cortical bone of human maxilla at the bone-miniscrew implant interface. In the experiment, a dry human skull with dental arches and all teeth present was used. A miniscrew implant was inserted in the interradicular region of the maxillary second premolar and molar region with 45-degree angulation. The miniscrew implant was loaded by nickel-titanium coil retraction spring which induces deformation in the cortical bone around the boneminiscrew implant interface. DSPI system was used for the measurement of out-of-plane and in-plane deformations induced in the cortical bone. In DSPI, two specklegrams are recorded corresponding to pre- and post-loading of the retraction spring. The DSPI fringe pattern is observed by subtracting these two recorded specklegrams. The phase information is obtained from a single DSPI fringe pattern by using Riesz transform method. The obtained phase is used to measure the deformation induced in the cortical bone. The experiment was repeated for different miniscrew implants with various lengths and diameters. The experimentally obtained results reveal that implant diameter and implant length affect the deformation induced in the cortical bone layer at the bone-miniscrew implant interface. The experimental results show that by increasing the length and the diameter of the miniscrew implants reduces the deformation in the cortical bone.