Faculty Bibliography

BACKGROUND: The versatility of the temporalis muscle justifies its wide popularity in reconstructive craniomaxillofacial surgery. In late facial paralysis, results of neural reconstructive techniques such as cross-facial grafting or mini-hypoglossal-to-facial nerve transfer are partial at best. In this series, the authors have used a segmental temporalis transfer, the 'mini-temporalis,' to augment the function attained with neural microsurgery. The aim of this present study was to present the experience of the authors' center with the use of the mini-temporalis as an adjuvant to facial nerve microsurgery for smile restoration. METHODS: Data were collected from 31 patients who underwent mini-temporalis transfer for smile restoration. In all patients, the mini-temporalis was used to augment the results of neural reconstructive techniques. Opting for the mini-temporalis related to a variety of reasons, after preoperative evaluation was weighed against the advantages and disadvantages of different reconstructive strategies on individual bases. Aesthetic and functional outcomes were evaluated by a panel of five independent observers using a five-category scale ranging from poor to excellent. RESULTS: All patients observed a follow-up longer than 3 months. Of 31 patients, 61.3 percent achieved excellent or good results and 29 percent achieved moderate results. All patients demonstrated an increase in the observers' scores after mini-temporalis transfer in comparison with the scores granted preoperatively or after neural microsurgery. Highly motivated patients committed to postoperative motor reeducation exhibited the best results. CONCLUSION: The clinical data presented support the use of mini-temporalis transposition in association with facial nerve microsurgery as a valuable alternative to free muscle transfer in selected cases

BACKGROUND: Evaluation of long-term outcomes of free-muscle transfer for smile restoration is overdue. Arguments for and against free-muscle transplantation in children are considered, and the debate on the influence of the growing skeleton on muscle function is revisited. This study evaluated the fate of free-muscle transfer over long follow-up periods in pediatric patients. METHODS: Thirty-two children with follow-up of 5 years or longer who received a free-muscle transfer for smile restoration were reviewed. To better analyze the effect of time, patients were classified into groups based on the length of follow-up: group A, 5 to 6 years; group B, 7 to 10 years; group C, 11 to 15 years; and group D, more than 15 years. Patients were videotaped at three stages: preoperatively, 2 years after free-muscle transfer, and at the last follow-up visit. Four independent observers graded patients' videotapes using a five-category scale ranging from poor to excellent. Panelists were asked to comment on any noticeable craniofacial disharmony with growth. RESULTS: All patients exhibited improved function and symmetry at 2 years after free-muscle transfer (averaged scores, p < 0.0001). A positive effect of time was seen in the long-term evaluation; observers' scores (p < 0.0001) and motor units on electromyography (p = 0.001) showed further improvement. No significance was found when comparing measured outcomes among the four follow-up groups, indicating that despite the growing skeleton, muscle function was maintained over time. CONCLUSIONS: These clinical data support the use of free-muscle transfer for smile restoration in children. The transplanted muscle appears to grow harmoniously with the craniofacial skeleton, and muscle function and aesthetic outcomes improved over time

BACKGROUND: Tissue engineering is often limited by the time required for culture expansion of cells necessary for scaffold seeding. Cell cycle regulators control entry and exit into the cell cycle and as such regulate cellular proliferation rates. The authors hypothesized that transient alteration in cell cycle regulators can be utilized as a means to accelerate stem cell proliferation. METHODS: Mesenchymal stem cells were harvested from wild-type mice and mice deficient in the cell cycle regulator p21. Wild-type cells were treated with small interfering RNA against p21 in two- or three-dimensional cultures in vitro. Cellular proliferation and the potential for cellular differentiation into the bone or fat lineage were assessed. RESULTS: Mesenchymal stem cells treated with small interfering RNA targeting p21 demonstrated a significant decrease in p21 protein and mRNA expression 96 hours after treatment. They also proliferated significantly faster than control cells (2.5 to three times) in both two- and three-dimensional culture. Similarly, cells harvested from p21-deficient mice demonstrated a significant acceleration in cellular proliferation. Inhibition of p21 expression was not associated with significant changes in spontaneous cellular differentiation. However, transient p21 inhibition promoted both osteoblastic and adipogenic differentiation when cells were exposed to differentiation medium. CONCLUSIONS: Transient inhibition of the cell cycle regulator p21 results in significant acceleration of mesenchymal stem cell proliferation without promoting spontaneous cellular differentiation. Exposure to differentiation medium results in increased cellular differentiation toward the osteoblast and fat lineage. Manipulation of cell cycle regulators may represent a novel means by which stem cell proliferation can be accelerated, thereby decreasing the time required for scaffold synthesis in tissue engineering.

Background: Ectopic beats are frequently associated with morphologic repolarization alterations of ensuing sinus beats. Less is known about repolarization duration alterations of post-ectopic sinus beats. In one patient who developed long QT and torsades de pointes upon exposure to a class III antiarrhythmic drug, and was later genotyped as being a carrier for long QT syndrome (LQTS) type 1, review of a pre-drug Holter monitor study revealed marked QT prolongation of post-ectopic sinus beats. In wondering whether this might be a common clue to "concealed" unexpressed LQTS, we realized that we must first characterize the range of post-ectopic QT prolongation present in normals. Prolongation beyond the upper limit of this range might then raise suspicion of possible LQTS and alter the antiarrhythmic drug selection process for the suppression of atrial fibrillation or other arrhythmias. Methods: Accordingly, we assessed the presence/degree of repolarization prolongation following premature ectopic impulses in 166 subjects with normal conduction intervals and normal repolarization on their resting 12-lead ECG, 75 of whom had no known associated cardiovascular disorder of any kind. That is, in our subjects, the maximal prolongation of the QT interval of the sinus beat following isolated ventricular and atrial premature complexes was characterized. Results: QT prolongation is common in post ectopic sinus beats. However, in our subjects the uncorrected QT interval of post-ectopic sinus beats never exceeded 480 ms in duration [which was much shorter than that seen (510-590 ms) in our gene carrier]. CONCLUSIONS: The QT interval in normal subjects may prolong following premature complexes but not to a value in excess of 480 ms.

The fundamental aspects of damage initiation and accumulation in one-piece zirconium oxide endosseous dental implants remain to be investigated. Aims: This study tested the null hypothesis that there is no influence on mouth-motion fatigue reliability and failure modes between as-received and after full crown preparation on one-piece ceramic implants. Methods: Forty-eight one-piece Y-TZP ceramic implants (Nobel Biocare, Goteborg, Sweden) were utilized. All specimens were embedded in acrylic resin exposing the first two threads at 30 degrees angulation with respect to the vertical axis (as per ISO specification 14801). Full crown preparations were performed following prosthodontic guidelines for half of the specimens. As-received and prepared specimens were distributed among three step-stress profiles based on the specimens ultimate fracture strength. Specimens were step-stress fatigued until failure or survival. A master Weibull curve was generated from the data and the reliability for completion of a mission of 50,000 cycles at 600 N load calculated. Results: No differences between the groups' reliability was observed. Failure mode for both groups was similar, where cracks initiated mainly at the tensile bending side of the second thread's internal diameter. The low Weibull modulus (<1) indicates that fatigue (<150,000 cycles) did not influence failure. Failure depended upon the applied load. Conclusion: Crown preparation did not influence the reliability of the one-piece ceramic implant. The null hypothesis was accepted. Fatigue did not influence the life time of ceramic implants at loads under 600 N. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008

Large acquired intracranial defects can result from trauma or surgery. When reoperation is required because of infection or tumor recurrence, management of the intracranial dead space can be challenging. By providing well-vascularized bulky tissue, intracranial microvascular free flaps offer potential solutions to these life-threatening complications. A multi-institutional retrospective chart and radiographic review was performed of all patients who underwent microvascular free-flap surgery for salvage treatment of postoperative intracranial infections between 1998 and 2006. A total of six patients were identified with large intracranial defects and postoperative intracranial infections. Four patients had parenchymal resections for tumor or seizure and two patients had posttraumatic encephalomalacia. All patients underwent operative debridement and intracranial free-flap reconstruction using the latissimus dorsi muscle ( N = 2), rectus abdominis muscle ( N = 2), or omentum ( N = 2). All patients had titanium ( N = 4) or Medpor ( N = 2) cranioplasties. We concluded that surgery or trauma can result in significant intracranial dead space. Treatment of postoperative intracranial infection can be challenging. Vascularized free tissue transfer not only fills the void, but also provides a delivery system for immune cells, antibodies, and systemically administered antibiotics. The early use of this technique when intracranial dead space and infection coexist is beneficial

The objective of this study was to physico/chemically characterize a commercially available and a newly developed Bioglass and also to evaluate their degradation properties. Materials and Method: Two bioresorbable glasses were utilized, a bioglass synthesized at Chemical Engineering College (University of Sao Paulo, Lorena, Sao Paulo) (BG1), and the other bioglass utilized was Biogran (BG2) (3i Implant Innovations, Brazil). Particles size distribution histograms were developed for both materials, and then they were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XR-D) and Fourier Transform Infrared (FTIR) before and after immersion in simulated body fluid (SBF) for 30, 60, and 90 days. Results: The particle size distribution showed that the mean particle diameters at 10%, 50%, and 90% of the total volume were 17.65, 66.18, and 114.71 mu m for BG1, and 354.54, 437.5, 525.00 mu m for BG2. SEM images of BG1 showed that the as-received material had a rough Surface and as the time of degradation elapsed, this surface became smooth. The images of BG2 showed that the as-received material also had a rough surface, and after immersion in SBF, the material's crystalline content/morphology could be observed. The X-ray diffraction recorded that BG1 showed a silica peak, not seen at BG2. FTIR revealed that both bioglasses were of similar composition, except for the CO3-carbonate minor peak, present at the BG2 sample. Conclusions: 1. The particle size distribution showed a polydispersed pattern for both materials. 2. The material Suffered degradation, and the decomposition increased as a function of immersion in SBF. 3. Both bioglasses had similar composition.