Orbital stress analysis, part V: systematic approach to validate a finite element model of a human orbit.

Unlabelled: The progress in computer technology and the increased use of finite element analysis in the medical field by nonengineers and medical researchers lead us to believe that there is a need to develop a systematic approach to validate a finite element model (FEM), of a human orbit, that simulates part of the maxillofacial skeleton and to investigate the effects and the clinical significance of changing the geometry, boundary conditions, that is, muscle forces, and orthotropic material properties on the predictive outcome of an FEM of a human orbit.

Methods: Forty-seven variables affecting the material properties, boundary conditions, and the geometry of an FEM of a human orbit including the globe were systematically changed, creating a number of FEMs of the orbit. The effects of the variations were quantified as differences in the principal strain magnitudes modeled by the original FEM (criterion standard), before the sensitivity analyses, and those generated by the changed FEMs.

Preemptive analgesic effect of low doses of celecoxib is superior to low doses of traditional nonsteroidal anti-inflammatory drugs.

Purpose: The purpose of the study was to compare the preemptive analgesic effect of celecoxib, a cyclooxygenase 2 inhibitor, with a traditional nonsteroidal anti-inflammatory drug, ibuprofen, in patients after minor oral surgery procedures.

Patients And Methods: This randomized, double-blind, placebo-controlled, prospective clinical trial was conducted over an 8-month period. Participants were randomly allocated to receive a standard oral dose of 200 mg celecoxib, 400 mg ibuprofen, or a placebo containing lactose, preemptively 1 h before surgery.

Orbital stress analysis, Part IV: Use of a "stiffness-graded" biodegradable implants to repair orbital blow-out fracture.

Purpose: The purpose of this study was to develop a finite element model (FEM) of a human orbit, of 1 patient, who had an orbital blow-out fracture, to study the effect of using a "stiffness-graded" (SG) biodegradable implant on the biomechanics of bone-fracture repair.

Methods: An FEM of the orbit and the globe, of 1 patient who had an orbital blow-out fracture and was treated with biodegradable poly-L/DL-lactide [P(L/DL)LA 70/30], was generated based on computed tomography scan images. Simulations were performed with a computer using a commercially available finite element software.

Orbital stress analysis: part III: biomechanics of orbital blowout fracture repair using bioresorbable poly-L/DL-lactide (P[L/DL]LA 70:30) implant.

Purpose Of The Study: The purpose was to study the biomechanics of bone fracture repair, of the orbital floor, using osteosynthetic bioresorbable implant and how to improve the implant design.

Materials And Methods: A finite element model of the orbit and the globe of 1 patient who experienced orbital blowout fracture and treated with bioresorbable poly-L/DL-lactide (P[L/DL]LA 70:30) implant (PolyMax; Synthes, Oberdorf, Switzerland) was generated based on computed tomographic scans. Simulations were performed with a computer using a commercially available finite element software.

Orbital stress analysis: part II: design and fixation of autogenous bone graft used to repair orbital blowout fracture.

Purpose Of The Study: The purpose of this study was to develop a finite element model (FEM) of a human orbit, who experienced a pure orbital blowout fracture, to study the effect of the geometrical mismatch-induced stresses on the orbital floor/graft interface and how to improve the graft design when restoring the orbital floor.

Materials And Methods: A FEM of the orbit and the globe of 1 patient who experienced pure orbital blowout fracture and treated with autogenous bone graft was generated based on computed tomographic scans. Simulations were performed with a computer using a commercially available finite element software NISA (EMRC, Troy, MI).

Microvascular stress analysis: Part II. Effects of vascular wall compliance on blood flow at the graft/recipient vessel junction.

Purpose: To develop a finite element model (FEM) to study the effect of the vascular wall compliance on blood flow at the graft/recipient vessel junction.

Materials And Methods: Finite element models of the end-to-end and end-to-side anastomoses were constructed. Simulations were performed with a computer using the finite element software NISA.

The cyclooxygenase-2 inhibitor celecoxib and alveolar osteitis.

Purpose Of The Study: The purpose of this study was to report our clinical experience, in a pilot study, of the use of the selective cyclooxygenase-2 (COX-2) inhibitor celecoxib, pre-emptively, to control pain in patients after surgical extraction of a mandibular molar tooth.

Patient And Methods: This randomised, double-blind, placebo-controlled, prospective clinical trial was conducted over an eight-month period. Participants were randomly allocated to receive a standard oral dose of 200 mg celecoxib, 400 mg ibuprofen, or a placebo containing lactose, pre-emptively, one hour before surgery.

Mobility determination of lead isotopes in glass for retrospective radon measurements.

In retrospective radon measurements, the 22-y half life of (210)Pb is used as an advantage. (210)Pb is often considered to be relatively immobile in glass after alpha recoil implanted by (222)Rn progenies. The diffusion of (210)Pb could, however, lead to uncertain wrong retrospective radon exposure estimations if (210)Pb is mobile and can escape from glass, or lost as a result of cleaning-induced surface modification.

One-stage zygomaticomandibular approach for improved access to the hemimaxilla and the middle base of the skull.

In this report, we describe a 1-stage zygomaticomandibular composite flap for improved access to the retromaxillary space and the base of the skull. The zygoma and the mandible were not detached from the facial musculature or from its overlying tissues, maintaining an optimum bone-soft tissue relationship. The advantage of this approach was the enhanced exposure of the deep lesion, which provided a shorter and wider view to the maxilla, the retromaxillary space, and the base of the skull.

Effects of tissue-engineered articular disc implants on the biomechanical loading of the human temporomandibular joint in a three-dimensional finite element model.

The purpose of this study was to evaluate biomechanical loading of the temporomandibular joint when using a biodegradable laminate implant to replace the articular disc and to test the hypothesis that the use of the implant reduces stress distribution in the condyle, implant, and glenoid fossa. A finite element model of a female human mandible, including the temporomandibular joint, which had two standard endosseous implants inserted bilaterally in the premolar region, was constructed from computed tomography scan images using a commercially available finite element software. The disc, condyle, and glenoid fossa were arbitrarily divided into five regions: the anterior, posterior, medial, lateral, and central.

WITHDRAWN: Stereolithography and the use of pre-adapted or fabricated plates for accurate repair of maxillofacial defects.

This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).

Central adenoid cystic carcinoma of the mandible: case report and literature review of 16 cases.

Central intraosseous adenoid cystic carcinoma (ACC) of the mandible, formerly known as cylindroma, is a rare neoplasm with only 16 cases reported in the literature. We describe the diagnosis, etiology, and treatment of a central ACC located in the mandibular premolar region. We also review the literature.

Microvascular stress analysis. Part I: simulation of microvascular anastomoses using finite element analysis.

Purpose Of The Study: To develop a finite element model (FEM) to study the effect of the stress and strain, in microvascular anastomoses that result from the geometrical mismatch of anastomosed vessels.

Material And Methods: FEMs of end-to-end and end-to-side anastomoses were constructed. Simulations were made using finite element software (NISA).

Reinnervation of arterial grafts by adrenergic nerves occurs in rats as indicated by increased levels of noradrenaline.

To investigate the changes in noradrenaline concentrations in transplanted arterial grafts in rats, 31 female rats 4 to 6 weeks old of the AO/Ks:OC strain were operated on. Femoral arterial grafts were anastomosed to carotid arteries and compared with control femoral segments. Six rats were included in each follow-up group at 0, 1, 4, and 12 weeks, and there were seven rats in the 20-week follow-up group.

Degeneration and regeneration of perivascular innervation in arterial grafts.

Because the understanding of postoperative changes in arterial graft innervation is limited, this study was performed to characterize neuronal degeneration and regeneration events immunohistochemically in femoral arterial grafts transplanted to carotid arteries in rats. Specimens taken 1 day, 3 days, 7 days, 1 month, 3 months, and 5 months after surgery were assessed for vasoactive intestinal peptide, neurofilaments, growth-associated protein 43, tyrosine hydroxylase, and nitric oxide synthase isoenzymes. During neuronal degeneration, vasoactive intestinal peptide disappeared within 1 day, transmitter-synthesizing enzymes (nitric oxide synthase and tyrosine hydroxylase) had vanished by day 7, and neurofilaments (cytoskeletal markers) had essentially disappeared after 1 week.

Noradrenaline levels rise significantly in rat arterial grafts at 6 hours postoperatively, and take 48 hours to come down.

The aim of this study was to investigate the rate of disappearance of noradrenaline in arterial grafts after their transplanation. Arterial grafts were harvested from AO/Ks:OC strain rats. In each rat, a graft was harvested from the femoral artery and transplanted into the common carotid artery.