Influence of bone parameters on peri-implant bone strain distribution in the posterior mandible

Objectives: The success rate of dental implants depends on the type of bone at the implant site. The purpose of the present study was to investigate the effects of the bone parameters at the implant-placement site on peri-implant bone strain distributions. Study Design: The morphologies and bone densities of seventy-five potential implant sites in the posterior mandible were measured using computed tomography (CT). Based on the CT data, we defined bone parameters (low and high in terms of cancellous-bone density and crestal-cortical bone density, and thin and thick in terms of crestal-cortical bone thickness), and we constructed finite-element models simulating the various bone types. A buccolingual oblique load of 200 N was applied to the top of the abutment. The von Mises equivalent (EQV) strains in the crestal-cortical bone and in the cancellous bone around the implant were calculated. Results: Cancellous-bone density greatly affected the maximum EQV strain regardless of the density and thickness of the crestal cortical-bone. The maximum EQV strains in the crestal cortical-bone and the cancellous bone in the low-density cancellous-bone models (of 150 Hounsfield units (HU) were 1.56 to 2.62-fold and 3.49 to 5.31-fold higher than those in the high-density cancellous-bone models (of 850 HU), respectively. The crestal cortical-bone density affected the maximum EQV strains in the crestal cortical-bone and in the cancellous bone in the low-density cancellous-bone models. The crestal cortical-bone thickness affected the maximum EQV strains in the cancellous bone and in the crestal cortical-bone in the low-density cancellous-bone models. Conclusions: Our results confirm the importance of bone types for the peri-implant bone strain distribution. Cancellous-bone density may be a critical factor for peri-implant bone strain. Key words:Dental implant, bone density, finite-element analysis.     

Bone metabolism of residual ridge beneath the denture base of an RPD observed using NaF-PET/CT

PatientA 66-year-old woman, who had a bilateral free-end edentulous mandible and no experience with dentures, was examined for the chief complaint of masticatory dysfunction on left side of dental arch. A unilateral distal extension removable partial denture (RPD) replacing lower-left molars was selected. Tomographic images were obtained using Fluorine-18 NaF positron emission computerized tomography (NaF-PET)/computed tomography (CT) before the RPD use and at 1, 6, and 13 weeks after the RPD use to observe the metabolic changes in residual bone caused by the RPD use. PET standardized uptake values (SUVs) and CT values were calculated for lower-left edentulous site (test side) and lower-right edentulous site (control side). As a result, SUVs on the control side remained static after the RPD use, whereas those on the test side increased at 1 and 6 weeks after the RPD use and then decreased. However, CT images showed no obvious changes in the bone shape and structure beneath RPD, and CT values both on the control and test sides did not change either.DiscussionThis report shows that NaF-PET could detect bone metabolic changes soon after the RPD use, which cannot be detected by clinical X-rays. The SUV changes may be a mechanobiological reaction to the pressure due to the RPD use, and wearing of the RPD may increase the bone turnover beneath denture.ConclusionThis report demonstrates that wearing of an RPD increases bone turnover beneath denture immediately after the RPD use without clinically detectable changes in bone structure or volume.     

LecT-hepa, a glyco-marker derived from multiple lectins, as a predictor of liver fibrosis in chronic hepatitis C patients

Assessment of liver fibrosis in patients with chronic hepatitis C (CHC) is critical for predicting disease progression and determining future antiviral therapy. LecT-Hepa, a new glyco-marker derived from fibrosis-related glyco-alteration of serum alpha 1-acid glycoprotein, was used to differentiate cirrhosis from chronic hepatitis in a single-center study. Herein, we aimed to validate this new glyco-marker for estimating liver fibrosis in a multicenter study. Overall, 183 CHC patients were recruited from 5 liver centers. The parameters Aspergillus oryzae lectin (AOL) / Dature stramonium lectin (DSA) and Maackia amurensis lectin (MAL)/DSA were measured using a bedside clinical chemistry analyzer in order to calculate LecT-Hepa levels. The data were compared with those of seven other noninvasive biochemical markers and tests (hyaluronic acid, tissue inhibitor of metalloproteases-1, platelet count, aspartate aminotransferase-to-platelet ratio index [APRI], Forns index, Fib-4 index, and Zeng's score) for assessing liver fibrosis using the receiver-operating characteristic curve. LecT-Hepa correlated well with the fibrosis stage as determined by liver biopsy. The area under the curve (AUC), sensitivity, and specificity of LecT-Hepa were 0.802, 59.6%, and 89.9%, respectively, for significant fibrosis; 0.882, 83.3%, and 80.0%, respectively, for severe fibrosis; and 0.929, 84.6%, and 88.5%, respectively, for cirrhosis. AUC scores of LecT-Hepa at each fibrosis stage were greater than those of the seven aforementioned noninvasive tests and markers. Conclusion: The efficacy of LecT-Hepa, a glyco-marker developed using glycoproteomics, for estimating liver fibrosis was demonstrated in a multicenter study. LecT-Hepa given by a combination of the two glyco-parameters is a reliable method for determining the fibrosis stage and is a potential substitute for liver biopsy. (HEPATOLOGY 2012).     

Electrochromic Os-based metallo-supramolecular polymers: electronic state tracking by in situ XAFS,IR, and impedance spectroscopies

In this study, the electronic states of Os-based metallo-supramolecular polymers (poly(OsL)²⁺) during electrochromism were tracked by in situ X-ray absorption fine structure (XAFS), infrared (IR), and impedance spectroscopies. The XAFS spectra suggested electronic charge migration in the polymer, and the in situ spectra revealed reversible changes caused by electrochemical redox reactions. The IR spectra of the polymers showed an IVCT band, and we also confirmed the reversible changes by applying a voltage to the redox cell. During the impedance measurements, we found a drastic decrease in the charge transfer resistance (R_CT) of the polymer films near the electrochemical redox potential.

In this study, the electronic states of Os-based metallo-supramolecular polymers (poly(OsL)²⁺) during electrochromism were tracked by in situ X-ray absorption fine structure (XAFS), infrared (IR), and impedance spectroscopies.     

Endoscopic Resection of Tuberculum Sellae Meningiomas

Objective To evaluate the results of endoscopic transnasal resection of tuberculum sellae meningiomas (TSMs) as compared with transcranial approaches.Design We retrospectively analyzed five patients who underwent endoscopic endonasal resection of TSM and performed a comprehensive review of articles published between 2000 and 2012 describing the operative treatment of TSMs.Results Gross total resection (GTR) was achieved in four patients (80%). Transient diabetes insipidus occurred in three patients (60%). Preoperative visual field deficit resolved in all patients. Cerebrospinal fluid (CSF) leak occurred in one patient. Analysis of published studies included 1,026 transcranial and 144 transnasal cases. GTR was achieved in 85% of transcranial and 72% of transnasal cases. Visual field deficit improved in 65% of transcranial and 82% of transnasal cases. Rate of diabetes insipidus and CSF leak was higher in the transnasal series. Rate of GTR and visual improvement was higher in endoscopic endonasal as compared with microsurgical transnasal series.Conclusion The literature supports transsphenoidal surgery for the resection of TSMs with significant optic nerve compromise and limited lateral extension. This approach may have an equivalent if not superior outcome over transcranial surgery in visual outcome. CSF leaks are still a challenge but may improve with the use of vascularized nasoseptal flaps.