Pre-operative drilling simulation method for dental implant treatment.

The position, depth and direction of implant placement are often planned based on evaluation of radiographs and study casts. Insertion planned in such a manner may not be adequate for precise and safe surgery in some cases due to inadequate working clearance in the oral cavity. In order to obtain high initial stability and ensure osseointegration at the implant-bone interface, careful and precise drilling must be performed at the implant placement site. Therefore, we propose the necessity of evaluating the operability of implant treatment-devices prior to surgery. The amount of handling space needed during implant placement surgery was determined. The results showed that for implants with a length of 7-18 mm, a vertical distance of as much as 50-60 mm was required, depending on the implant platform. These results suggest the necessity of pre-operative drilling simulation in each individual. Handling space was measured with angled heads and probes fabricated on a trial basis for pre-surgical drilling simulation in the oral cavity. We believe that these instruments may be clinically useful in estimating the amount of handling space required prior to surgery and ensuring precise implant placement. Evaluation of the intra-oral environment for handling of treatment devices should be included in the pre-surgical intra-oral evaluation of dental implant cases to avoid changes in treatment planning due to intra-oral interference during the course of surgery.

A model for studying epithelial attachment and morphology at the interface between skin and percutaneous devices.

Percutaneous devices are indispensable in modern medicine, yet complications from their use result in significant morbidity, mortality, and cost. Bacterial biofilm at the device exit site accounts for most infections in short-term devices. We hypothesize that advanced biomaterials can be developed that facilitate attachment of skin cells to percutaneous devices, forming a seal to preclude bacterial invasion. To study the skin/biomaterial interface systematically, we first identified biomaterials with physical properties compatible with histological processing of skin. Second, we developed an organ culture system to study skin response to implants. Organ cultures implanted with porous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] or polytetrafluoroethylene (PTFE) could easily be evaluated histologically with preservation of the skin/biomaterial interface. Epithelial cells migrated down the cut edges of the biomaterial in a pattern seen in marsupialization of percutaneous devices in vivo. This in vitro model maintains skin viability and allows histologic evaluation of the skin/biomaterial interface, making this a useful, inexpensive test-bed for studies of epidermal attachment to modified biomaterials.

Globular domains 4/5 of the laminin alpha3 chain mediate deposition of precursor laminin 5.

In epidermal wounds, precursor laminin 5 (alpha3beta3gamma2) is deposited in the provisional basement membrane (PBM) before other BM components. Precursor laminin 5 contains G4/5 globular domains at the carboxyl terminus of the alpha3 chain. Here, the function of G4/5 was evaluated in deposition of laminin 5. Soluble laminin 5, secreted by keratinocytes in culture, is cleaved by an endogenous protease releasing G4/5. Thrombin, a serum protease, cleaves G4/5 indistinguishably from endogenous protease. Soluble human precursor laminin 5, but not cleaved laminin 5, was bound and deposited by mouse keratinocytes null for mouse alpha3 chain (alpha3-/- MKs). The deposition rescued adhesion and spreading and survival. In a model for PBM assembly, precursor laminin 5 was deposited along fibronectin fibrils at the junction between co-cultures of keratinocytes and fibroblasts. In both models, the deposition of precursor laminin 5 was inhibited by removal of G4/5 with thrombin. To confirm that G4/5 participates in deposition, the human LAMA3A gene was modified to produce alpha3 chains either without or with G4/5 that cannot be cleaved. Both precleaved and noncleavable alpha3 isoforms were expressed in alpha3-/- MKs, where they deposited sufficiently to rescue adhesion via integrins alpha3beta1 and alpha6beta4. Despite this similarity, noncleavable laminin 5 was at least threefold more efficiently deposited than precleaved isoform. We conclude that the G4/5 domain in the alpha3 chain facilitates deposition of precursor laminin 5 into the PBM in epidermal wounds.

Clinical evaluation of osseointegrated implants in Tokyo Dental College Hospital (third report): long-term observation of functioning survival rate of fixtures.

The objective of this report was to review 365 cases of Brånemark Implant Bridge including 1,444 fixtures in patients of Tokyo Dental College Chiba Hospital. The term of implantation was divided into several phases; less than 1 year, from 1 year to 3 years, from 3 years to 5 years, from 5 years to 7 years, from 7 years to 10 years, more than 10 years, and the survival rate was calculated for each phase. The removal rate of fixture after connecting the superstructure was 13% in maxillary cases and 2% in mandibular cases. The functioning survival rate in maxillary cases slightly decreased from 91% in less than 1 year to 87% after more than 10 years; however, the functioning survival rate in mandibular cases was about 99% in all periods. The removal rate of fixtures per patient was 23% in maxillary cases and 6% in mandibular ones. The average removal number of fixtures was 1.8 in maxillary cases and 1.2 in mandibular ones. The removal of the fixture occurred most frequently at less than 1 year in maxillary cases, but there was no tendency for a pattern of removal of fixture in mandibular cases.

Painful indurated erythema suggestive of Kikuchi-Fujimoto disease in a patient with primary Sjögren's syndrome.

We report a patient with primary Sjögren's syndrome who developed pyrexia, cervical lymphadenopathy, and painful indurated erythema on the forehead, back, chest, abdomen, and limbs. Laboratory data showed an elevated erythrocyte sedimentation rate, C-reactive protein and CH50 in addition to existing autoantibodies including anti-nuclear antibody, anti SS-A antibody, and anti SS-B antibody. A skin biopsy specimen showed focal infiltration of histiocytes with non-neutrophilic karyorrhetic debris in the dermis and subcutaneous fat tissue. Immunohistochemically the infiltrated cells were stained for CD68, suggesting cutaneous involvement of Kikuchi-Fujimoto disease. All symptoms and laboratory data improved within three weeks after treatment with 20 mg/day of prednisolone. The present case suggests that a pathophysiological condition similar to Kikuchi-Fujimoto disease can develop during the long-term course of Sjögren's syndrome.