ABSTRACT
The present study analyzed stress distributions in craniofacial structures around implant-supported maxillary prostheses. Using post-hemimaxillectomy computed tomography (CT) of a patient, the authors constructed a three-dimensional (3D) solid model using Digital Imaging and Communications in Medicine data (DICOM data) for maxillofacial and cranial bones. The effects of different prosthesis designs on stress distributions in craniofacial bones and osseous tissues around the implants were biomechanically investigated using 3D finite-element analysis. Maxillary prostheses were designed with 2 implants in the zygoma on the affected side and 2-3 implants in the maxillary alveolar bone on the unaffected side, without using a cantilever. Zygomatic implants provided suitable stress dispersal to the zygomatic and craniofacial bones on the affected side. This information is useful for designing maxillary prostheses.
Subject(s)
Dental Abutments , Dental Implantation, Endosseous/methods , Dental Prosthesis Design/instrumentation , Dental Prosthesis, Implant-Supported , Dental Stress Analysis/instrumentation , Maxillary Neoplasms/surgery , Biomechanical Phenomena , Computer Simulation , Dental Implants , Dental Stress Analysis/methods , Finite Element Analysis , Humans , Imaging, Three-Dimensional , Jaw, Edentulous/diagnostic imaging , Jaw, Edentulous/surgery , Male , Middle Aged , Models, Dental , Patient Care Planning , Radiography , Stress, Mechanical , Zygoma/surgeryABSTRACT
The objective of this study was to analyse stress distribution in craniofacial structures around zygomatic osseointegrated implants. An integrated system for Digital Imaging and Communications in Medicine (DICOM) data were utilized to create a three-dimensional model of craniofacial structures. The amount and distribution of the main stresses were compared using three-dimensional finite elemental analysis. The system allowed visual confirmation and analysis of stress distribution as well as the convenient and simple construction of a digital biomechanical model that provided details of anatomical structures in the regions of interest. Zygomatic implants with or without connected implants supporting the superstructure were compared. Stresses in severely resorbed maxillae with connected implants were not concentrated around the alveolar bone supporting the zygomatic implants. Stresses where there were no connected implants tended to be generated in the zygomatic bone, at the middle part of the zygomatic implant and at the joint of the fixture-abutment. Stress due to occlusal forces is mainly supported by the zygomatic bone, is transferred predominantly through the infrazygomatic crest, and is divided between the frontal and temporal processes of the zygomatic bone in different directions.
Subject(s)
Dental Implants , Finite Element Analysis , Zygoma/physiology , Alveolar Process/physiopathology , Biomechanical Phenomena , Bite Force , Bone Resorption/physiopathology , Dental Abutments , Dental Prosthesis Design , Humans , Image Processing, Computer-Assisted , Imaging, Three-Dimensional , Maxilla/physiology , Maxilla/surgery , Maxillary Diseases/physiopathology , Osseointegration/physiology , Stress, Mechanical , Tomography, X-Ray Computed , Zygoma/surgeryABSTRACT
A cleavage product of alpha-fodrin may be an important organ-specific autoantigen in the pathogenesis of Sjogren's syndrome (SS), but the mechanisms of alpha-fodrin cleavage remain unclear. Since EBV has been implicated in the pathogenesis of SS, we determined whether EBV activation could induce the SS-specific 120-kDa autoantigen alpha-fodrin. ZEBRA mRNA expression, a marker for activation of the lytic cycle of EBV, was found in the salivary gland tissues from SS patients, but not in those from control individuals. ZEBRA-expressing lymphoid cells were also found in the SS glands in double-stained immunohistochemistry. Furthermore, a significant link between production of Abs against 120-kDa alpha-fodrin and reactivated EBV Ag was found in sera from patients with SS, but not in those from control individuals. EBV-activated lymphoid cells showed specific alpha-fodrin cleavage to the expected 120-kDa fragments in vitro. Pretreatment with caspase inhibitors inhibited cleavage of alpha-fodrin. Thus, an increase in apoptotic protease activities induced by EBV reactivation may be involved in the progression of alpha-fodrin proteolysis in the development of SS.
Subject(s)
Autoantigens/immunology , Autoantigens/metabolism , Carrier Proteins/immunology , Carrier Proteins/metabolism , Herpesvirus 4, Human/immunology , Leucine/analogs & derivatives , Microfilament Proteins/immunology , Microfilament Proteins/metabolism , Sjogren's Syndrome/immunology , Amino Acid Chloromethyl Ketones/pharmacology , Apoptosis/immunology , Aprotinin/pharmacology , Autoantigens/biosynthesis , Carrier Proteins/antagonists & inhibitors , Carrier Proteins/biosynthesis , Caspases/metabolism , Cysteine Proteinase Inhibitors/pharmacology , DNA-Binding Proteins/biosynthesis , Humans , Hydrolysis , Leucine/pharmacology , Leupeptins/pharmacology , Microfilament Proteins/antagonists & inhibitors , Microfilament Proteins/biosynthesis , Molecular Weight , Organ Specificity/immunology , Pepstatins/pharmacology , Sjogren's Syndrome/enzymology , Sjogren's Syndrome/virology , Trans-Activators/biosynthesis , Tumor Cells, Cultured/cytology , Tumor Cells, Cultured/enzymology , Tumor Cells, Cultured/metabolism , Viral Proteins/biosynthesis , Virus Activation/immunologyABSTRACT
AIM: To determine whether transforming growth factor-beta 1 (TGF-beta 1) has a pathogenetic role in disease of the salivary glands. METHODS: An indirect immunohistochemical technique was used to analyse TGF-beta 1 expression in six specimens of normal salivary gland and 23 surgical specimens. RESULTS: TGF-beta 1 was strongly expressed in the ductal epithelial cells of normal salivary gland tissues (six of six cases) and in inflammatory conditions (eight of 11 cases). In contrast, TGF-beta 1 was not detectable in ductal epithelial cells expressing HLA-DR around infiltrating CD4+ CD45RO+ activated T cells, in the salivary gland tissue of patients with Sjögren's syndrome. CONCLUSION: Because TGF-beta 1 has an essential role in the mucosal immunity of salivary glands, abnormal expression of this cytokine must be regarded as a candidate in the pathogenesis of Sjögren's syndrome.
