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Although the reported percentage of bone-implant contact is far lower than 100%, the cause of such low levels of bone formation has rarely been investigated. This study tested the negative biological effect of hydrocarbon deposition onto titanium surfaces, which has been reported to be inevitable. Osteogenic MC3T3-E1 cells were cultured on titanium disks on which the carbon concentration was experimentally regulated to achieve carbon/titanium (C/Ti) ratios of 0.3, 0.7, and 1.0. Initial cellular activities such as cell attachment and cell spreading were concentration-dependently suppressed by the amount of carbon on the titanium surface. The osteoblastic functions of alkaline phosphatase activity and calcium mineralization were also reduced by more than 40% on the C/Ti (1.0) surface. These results indicate that osteoblast activity is influenced by the degree of hydrocarbon contamination on titanium implants and suggest that hydrocarbon decomposition before implant placement may increase the biocompatibility of titanium.

Background: Non-selective cyclooxygenase (COX) inhibitors (non-steroidal anti-inflammatory drugs) inhibit large bowel carcinogenesis in patients with familial adenomatous polyposis (FAP). Their role in the duodenum of these patients is less certain. [...]

The determination of a pure ErVO4 crystal at room temperature using Ramon scattering methods is described.

This article discusses a case of a 64-year-old man who was found to have a pancreatic head mass during a follow-up for colon cancer. The mass was confirmed to be a solid pseudopapillary neoplasm (SPN) through a biopsy. The tumor had invaded the main pancreatic duct and showed high-grade malignant transformation. Metastases developed in the para-aortic lymph nodes and liver one year after surgery. The article highlights the importance of careful treatment for patients with SPN suspected of having high-grade malignant transformation. [Extracted from the article]

The phonon dispersion curves of Nb3Sb have been studied by inelastic neutron scattering. All the branches have been determined in the main symmetry directions and the results are analyzed with Born-von Kármán models of different complexity. A model with general forces up to the eighth-nearest neighbors gives excellent agreement with experiment. However, a rather good description of the dispersion curves is obtained with a model including axially symmetric forces up to the third-nearest neighbors, which indicates that these interactions are dominant. Temperature effects were found to be very small. Additional experiments were performed on polycrystalline samples to determine directly the phonon density of states. Our results obtained on Nb3Sb are compared with the available phonon data on Nb3Sn. © 1983 The American Physical Society.

Purpose: The effect of gingival coverage by removable partial dentures (RPDs) on bacterial accumulation has not been sufficiently established. The aim of this study was to evaluate the periodontal and microbiologic reactions to mandibular major connectors. It was hypothesized that the use of a lingual plate increases the risk of periodontal disease.Materials and Methods: Fourteen subjects (mean age: 69.0 years) received oral hygiene instructions and ultrasonic debridement prior to examination. Each subject received an experimental RPD incorporating either a lingual bar or lingual plate for the first 8 weeks and was then switched to the other option for the next 8 weeks. Clinical parameters (Plaque Index, Gingival Index, probing depth, and tooth mobility) were recorded. Subgingival plaque samples were collected from the periodontal pocket in the test site to measure the colonization of periodontal pathogens after the use of each denture.Results: The mean probing depth was significantly greater after use of the lingual plate compared to the lingual bar (P < .05), whereas the type of connector did not affect the levels of any of the microbial species. All subjects that exhibited at least one bacterial species showed smaller numbers of microorganisms at the second examination than at the first.Conclusions: The lingual cervical coverage did not precipitate the accumulation of anaerobic microorganisms, although it could potentially induce gingival inflammation. The results suggest that a lingual plate can be used as safely as a lingual bar if oral and denture hygiene are carefully monitored. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to assess the influence of mandibular morphology on the stress and strain distributions in the bone supporting an implant. Materials and Methods: Subjects were selected from patients with missing mandibular premolar teeth. Computed tomographic scans of the premolar region were classified into nine groups based on the overall bone morphology and the relative position of the alveolar crest. Finite element models of the bone on the basis of this classification, with inserted implants and superstructures, were constructed. A load of 200 N applied 30 degrees buccal from the vertical axis was directed toward the occlusal surface. Results: One hundred two partially (n = 98) and completely (n = 4) edentulous subjects were recruited. Their ages ranged from 40 to 79 years (mean age, 60.5 years; 41 men and 61 women). Approximately 56% of the patients showed bone widening in the caudal direction. The maximum compressive stresses were shown in the lingual cervical regions. An influence of overall bone morphology on stress distribution was not observed; however, the alveolar crest contour clearly affected the maximum stress and strain values. Compressive microstrain above 4,000 was observed only when the alveolar crest was lingually located relative to the body of the mandible. These high strain levels were concentrated at the lingual cervical margin, with volumes ranging from 0.04 to 0.07 mm3. Conclusion: The contour of the alveolar crest potentially plays a critical role in maintaining the bone levels surrounding implants. Int J Oral Maxillofac Implants 2010;25:482-490. [ABSTRACT FROM AUTHOR]

The phonon modes of a pure ErVO crystal were determined at room temperature using Raman scattering methods, and the observed frequencies were assigned according to group theory in terms of the internal modes of the VO ions and the external modes of the Er(VO) lattice. The assignments of the phonon modes match well with the overall phonon systematics of the rare-earth orthovanadate series, and the results presented here reinforce the general trend of bonding strength in the zircon series of RVO, RAsO, and RPO materials. c 2001 American Institute of Physics. [DOI: 10.1063/1.1384858]. [ABSTRACT FROM AUTHOR]