Faculty Bibliography

Among dental implant design alterations, surface modifications have been by far the most investigated topic. Regarding implant surface research, the lack of hierarchical approaches relating in vitro, in vivo, clinical trials, and ex vivo analyses has hindered biomaterials scientists with clear informed rationale guidelines for implant surface design. This manuscript provides a critical hierarchical overview of the in vitro, laboratory in vivo, clinical, and ex vivo methodologies used to investigate the performance of novel biomaterials aiming to allow dental professionals to better evaluate the past, present, and future dental implant surface research. This manuscript also contains an overview of the commercially available surface texture and chemistry modifications including novel nanotechnology-based fabrication processes. Over the last decade, surface texturing has been the most utilized parameter for increasing the host-to-implant response. Recently, dental implant surfaces utilizing reduced length scale physico/chemical features (atomic and nanometric) have shown the potential to synergistically use both texture and the inclusion of bioactive ceramic components on the surface. Although surface modifications have been shown to enhance osseointegration at early implantation times, information concerning its long-term benefit to peri-implant tissues is lacking due to the reduced number of controlled clinical trials. Given the various implants/surfaces under study, the clinician should ask, founded on the basic hierarchical approach described for the in vitro, laboratory in vivo data, as well as the results of clinical studies to effectiveness before use of any dental implant

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.

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

Incorporation of bioceramics on the surface of dental implants has been utilized in an attempt to increase biological response of bone to materials. This paper reports the in vitro biological evaluation of Ca/P-based nanothickness bioceramic coated alumina-blasted/acid-etched titanium implants (AB/AE nanotite implant) and compare its performance to the untreated and uncoated implants, Ca/P-based nanothickness bioceramic coated untreated implants (untreated nanotite implant), alumina-blasted/acid-etched titanium implants (AB/AE implant) and hydroxyapatite plasma-sprayed implants (PSHA Implant). Balb/c 3T3 fibroblasts were used to asses the cytocompatibility of implant materials according to ISO-10993-5 protocols. Osteablasts from Balb/c femurs seeded onto different implant surfaces showed the effect of surface topography and chemistry on cell adhesion. The results showed that all implants were not cytotoxic and that PSHA and AB/AE nanotite implants favored osteoblasts adhesion.

The objective of this series of experiments was to evaluate the effect of bioceramic coatings/ incorporations on implant surfaces as a function of implant and surgical drilling design. Methods: A series of four in vivo studies were conducted utilizing the dog proximal tibia model. The models provided implants that remained from 2 to 5 weeks implantation time. The different studies comprised the placement of implants with intimate contact with bone following placement and implant designs that resulted in healing chambers. The various implant types presented surfaces with and without Ca- and P-based bioceramic incorporations. Biomechanical and histomorphometric measurements along with qualitative bone-implant interface morphology evaluation were performed. For all studies, one-way ANOVA at 95% level of significance was employed along with Tukey's post-hoc multiple comparisons. Results: Close contact between cortical and trabecular bone and all the different implant surfaces irrespective of implant fit (with and without healing chambers) showed that all surfaces were biocompatible and osteoconductive. In general, appositional bone healing was observed at all implant regions that were in intimate contact with bone immediately after placement, and an intramembranous-like healing occurred throughout the whole volume of the healing chambers. Irrespective of implant + surgical drilling design, the presence of Ca- and P resulted in a bone morphology that showed primary osteonic structures at earlier times than uncoated surfaces. Conclusion: Irrespective of implant design and surgical drilling combination, the presence of Ca and P on the implant surface positively modulated early healing around endosseous implants.

Among surface modifications commercially available for dental implants, the incorporation of bioceramic coatings is one of the most popular. However, concerns regarding the effectiveness of the bond between the metallic Surface and the coating have led to the development of thin-film Ca- and P- based bioceramic coatings. The purpose of this study was to evaluate the early bone response to a thin ion bean deposited (Test) bioceramic implant surface compared to an alumina-blasted/acid-etched (Control) surface in a canine model. Results showed that although no difference in bone-to-implant (BIC) could be noted between the two different surfaces, more organized bone architecture was present around the Test implants in 4 weeks. Based on this observation, the incorporation of a thin- film bioceramic coating positively influenced bone healing around dental implants at early times.