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BACKGROUND Because of bisphosphonate medication, dental implantation with a subsequent infection poses a relevant risk factor to suffer from medication-related osteonecrosis of the jaw. This rat study evaluated different implant materials under systemic bisphosphonate delivery using micro-computed tomography (μCT) images. METHODS Fifty-four rats were randomly allocated into a control group 1, test group 2 with intravenous drug application of zoledronic acid and test group 3 with a subcutaneous application of alendronic acid. After 4 weeks of drug delivery, the first molar on each side of the upper jaw was extracted, and either a zirconia or a titanium implant was immediately inserted. Radiological examinations at four timepoints before the operation, 1 week later, 6 weeks later and after 12 weeks of follow up included μCT measurements of the in vivo peri-implant bone loss. μCT measurements of the ex vivo peri-implant bony structure after 12 weeks follow-up covered the bone mineral density, -volume, -trabecular thickness and -separation. RESULTS Both test groups showed a significant increase in bone loss over time (P

The purpose of this study was to evaluate bone healing in calvarial defects using two bone graft substitute materials; biphasic beta-tricalcium phosphate/hydroxyapatite in hydrogel (s-TCP/HA) versus composite non-demineralized xenogenic dentin with s-TCP/HA mixture. Full thickness critical-sized defects were created bilaterally in 10 New Zealand male rabbits. Seven defects were left empty, six filled with biphasic tricalcium phosphate putty, and seven were filled with composite non-demineralized xenogenic dentin with biphasic tricalcium phosphate. Animals were sacrificed at eight weeks postoperatively and the healing of the biomaterial-filled defects was compared radiographically and by histomorphometry. Micro-computed tomography (μCT) was utilized to analyze the osteogenesis and healing patterns of the defects. Quantitative analysis of volume fraction (%) of the newly formed bone and remaining graft material (FV=filling volume/TV=tissue volume) and mean intensity [HU] in the defects were evaluated. Defects filled with composite dentin with biphasic tri-calcium phosphate showed volume fraction (FV/TV) in the order of 55.81% ± 17.72%, whereas defects filled with only biphasic tricalcium phosphate showed a fraction of 39.84% ± 16.06%, which represent the ratio of remaining graft material and new bone formation to the tissue volume. The empty negative control defects showed a volume fraction of 19.14% ± 8.787%. Histological analysis showed significant percentage increase in bone formation and residual graft with the composite Dentin/s-TCP group after 8 weeks. The findings suggest that composite xenogenic dentin with biphasic tricalcium phosphate showed improved osteogenesis when compared to biphasic tricalcium phosphate without the addition of non-demineralized dentin. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 773-782, 2019.

Fluorescence-mediated tomography (FMT) enables noninvasive assessment of the three-dimensional distribution of near-infrared fluorescence in mice. The combination with micro-computed tomography (µCT) provides anatomical data, enabling improved fluorescence reconstruction and image analysis. The aim of our study was to assess sensitivity and accuracy of µCT-FMT under realistic in vivo conditions in deeply-seated regions. Accordingly, we acquired fluorescence reflectance images (FRI) and µCT-FMT scans of mice which were prepared with rectal insertions with different amounts of fluorescent dye. Default and high-sensitivity scans were acquired and background signal was analyzed for three FMT channels (670 nm, 745 nm, and 790 nm). Analysis was performed for the original and an improved FMT reconstruction using the µCT data. While FRI and the original FMT reconstruction could detect 100 pmol, the improved FMT reconstruction could detect 10 pmol and significantly improved signal localization. By using a finer sampling grid and increasing the exposure time, the sensitivity could be further improved to detect 0.5 pmol. Background signal was highest in the 670 nm channel and most prominent in the gastro-intestinal tract and in organs with high relative amounts of blood. In conclusion, we show that µCT-FMT allows sensitive and accurate assessment of fluorescence in deep tissue regions.

Objectives X-ray-based planning and post-implantation assessment of titanium implants is the commonly accepted standard to date. However, new implant materials such as zirconia (ZrO2) have become available, and magnetic resonance imaging may be a valuable alternative with these implants. The present in vitro study investigated artifacts produced by titanium and zirconia implants in magnetic resonance imaging (MRI) and assessed the accuracy of pre-implant planning and post-implantation assessment comparing MRI to standard X-ray-based imaging modalities: Orthopantomogram (OPT), cone beam (CBCT), and computed tomography (CT). Materials and methods Twelve porcine mandibles were prepared and scanned (MRI, OPT, CBCT, μCT), and bone height above the nerve canal was measured. Specimens were implanted with either two titanium or zirconia implants and rescanned to investigate the influence of implant materials on post-implantation assessment. MRI and μCT artifacts were quantified with implants embedded in gelatin phantoms and porcine specimens. Results Compared with CBCT set as standard, μCT, OPT, and MRI showed similar accuracy in pre-op bone height measurements. Post-implantation, while titanium implants induced a strong B0-field distortion resulting in extensive signal voids, zirconia implants were clearly depictable with only minor distortions. Conclusions Excellent contrast, limited artifacts, radiation-free and accurate implant assessment may indicate that MRI is a valuable imaging alternative for zirconia-based implant dentistry.