Evaluation of Pre- and Post-loading Peri-implant Crestal Bone Levels Using Cone-beam Computed Tomography: An In Vivo Study.

AIM: To evaluate the buccal, lingual, mesial, and distal crestal bone around implant using CBCT analysis having buccal crestal bone width of 1 mm after placement of implant and after 3 months of loading. MATERIALS AND METHODS: Twenty-five patients between 18 and 60 years of age with adequate bone width and height were selected for this in-vivo study with single or multiple missing teeth. Surgical stent was fabricated for all of them by using self-cure acrylic resin for selection of implant according to the availability of bone, and gutta-percha was used as radio-opaque marker to locate the implant site. After proper analysis, in the first stage surgery, implants were placed. After 3 months to this, the second stage surgery was performed followed by elastomeric impression for porcelain fused to metal prosthesis fabrication. The buccal, lingual, mesial, and distal bone width and height were evaluated by using cone-beam computed tomography (CBCT). CBCT was standardized in terms of FOV (field of vision), slice thickness, and interval. After 3 months of loading, CBCT was taken to evaluate the alteration in the crestal bone around implants. Pre- and post-loading, crestal bone on four locations was measured by using CBCT software. RESULTS: There is significant bone loss at all the locations, buccal, lingual, mesial, and distal, at the time of placement and after 3 months of loading of implant (p <0.05). The mean difference of 0.840, 0.933, 0.840, and 0.380 at buccal, lingual, mesial, and distal locations, respectively, shows statistically significant difference in pre- and post-values of mean bone loss at buccal, lingual, mesial, and distal positions. Pre-loading bone loss was maximum in the distal surface, while post-loading bone loss was maximum in the buccal surface. CONCLUSION: From this study, it is concluded that although crestal bone loss was higher before implant placement, there was significant alteration in crestal bone even after loading of implant. CLINICAL SIGNIFICANCE: It is widely accepted that the bone loss around the implant crest module is multidisciplinary in nature. Long-term preservation of the crestal bone is a paramount for successfully functioning of dental implants. Preserving crestal bone will help in dissipating the functional load. With proper treatment planning by the practitioner, this technical contribution to the crestal bone loss can be minimized and long-term survival of dental implants can be achieved.

Pre-surgical Prediction of Ischemic Mitral Regurgitation Recurrence Using In Vivo Mitral Valve Leaflet Strains.

Ischemic mitral regurgitation (IMR) is a prevalent cardiac disease associated with substantial morbidity and mortality. Contemporary surgical treatments continue to have limited long-term success, in part due to the complex and multi-factorial nature of IMR. There is thus a need to better understand IMR etiology to guide optimal patient specific treatments. Herein, we applied our finite element-based shape-matching technique to non-invasively estimate peak systolic leaflet strains in human mitral valves (MVs) from in-vivo 3D echocardiographic images taken immediately prior to and post-annuloplasty repair. From a total of 21 MVs, we found statistically significant differences in pre-surgical MV size, shape, and deformation patterns between the with and without IMR recurrence patient groups at 6 months post-surgery. Recurrent MVs had significantly less compressive circumferential strains in the anterior commissure region compared to the recurrent MVs (p = 0.0223) and were significantly larger. A logistic regression analysis revealed that average pre-surgical circumferential leaflet strain in the Carpentier A1 region independently predicted 6-month recurrence of IMR (optimal cutoff value - 18%, p = 0.0362). Collectively, these results suggest greater disease progression in the recurrent group and underscore the highly patient-specific nature of IMR. Importantly, the ability to identify such factors pre-surgically could be used to guide optimal treatment methods to reduce post-surgical IMR recurrence.

Individualized Characterization of the Distribution of Collagen Fibril Dispersion Using Optical Aberrations of the Cornea for Biomechanical Models.

Purpose: The spatial distribution of collagen fibril dispersion has a significant impact on both corneal biomechanical and optical behaviors. The goal of this study was to demonstrate a novel method to characterize collagen fibril dispersion using intraocular pressure (IOP)-induced changes in corneal optical aberrations for individualized finite-element (FE) modeling. Methods: The method was tested through both numerical simulations and ex vivo experiments. Inflation tests were simulated in FE models with three assumed patterns of collagen fibril dispersion and experimentally on three rhesus monkey corneas. Geometry, matrix stiffness, and the IOP-induced changes in wavefront aberrations were measured, and the collagen fibril dispersion was characterized. An individualized corneal model with customized collagen fibril dispersion was developed, and the estimated optical aberrations were compared with the measured data. Results: For the theoretical investigations, three assumed distributions of fibril dispersion were all successfully characterized. The estimated optical aberrations closely matched the measured data, with average root-mean-square (RMS) differences of 0.29, 0.24, and 0.10 µm for the three patterns, respectively. The overall features of the IOP-induced changes in optical aberrations were estimated for two ex vivo monkey corneas, with average RMS differences of 0.57 and 0.43 µm. Characterization of the fibril dispersion in the third cornea might have been affected by corneal hydration, resulting in an increased RMS difference, 0.8 µm. Conclusions: A more advanced corneal model with individualized distribution of collagen fibril dispersion can be developed and used to improve our ability to understand both biomechanical and optical behaviors of the cornea.