Status of alloplastic total temporomandibular joint replacement procedures performed by members of the American Society of Temporomandibular Joint Surgeons.

The purpose of this study was to assess the number of alloplastic total temporomandibular joint replacement (TMJ TJR) devices implanted and the complications encountered by members of the American Society of Temporomandibular Joint Surgeons (ASTMJS). A questionnaire was developed using REDCap (Chicago, IL) and an on-line link was e-mailed four times over a 6-week period (February to March 2015) to all members of the ASTMJS. The questionnaire included eight questions related to the surgeon's TMJ TJR experience. A Likert scale was included to assess the respondents' opinions concerning the future demand for TMJ TJR and their thoughts on potential device improvements. The study sample was composed of 36 ASTMJS respondents (42.4%). TMJ TJR is performed successfully and in relatively high numbers by members of the American Society of Temporomandibular Joint Surgeons.

Examination of failed retrieved temporomandibular joint (TMJ) implants.

In the management of end-stage temporomandibular joint disorders (TMD), surgeons must often resort to alloplastic temporomandibular joint (TMJ) total joint replacement (TJR) to increase mandibular function and form, as well as reduce pain. Understanding wear and failure mechanisms of TMJ TJR implants is important to their in vivo longevity. However, compared to orthopedic TJR devices, functional wear of failed TMJ TJR implants has not been examined. Not only do wear and corrosion influence TJR implant in vivo longevity, but so does reactivity of peri-implant tissue to these two events. The aim of this study was to examine and report on the wear of retrieved, failed metal-on-metal (MoM), metal-on-polymer (MoP), and titanium-nitride coated (TiN Coated) TMJ TJR implant components. A total cohort of 31 TMJ TJR devices were studied of which 28 were failed, retrieved TMJ TJRs, 3 were never implanted devices that served as controls. The mean time from implantation to removal was 7.24 years (range 3-15), SD 3.01. Optical microscopy, White Light Interferometry (WLI), Scanning Electron Microscopy (SEM), and Raman spectroscopy were utilized to characterize the surfaces of the devices. Data was acquired and evaluated by analyzing alloy microstructure. Substantial surface damage was observed between the articulating areas of the condylar head and the glenoid fossa components. Damage included pitting corrosion, evidence of deposited corrosion products, specific wear patterns, hard phases, surface depressions, and bi-directional scratches. Electrochemical analysis was performed on the MoM Control, retrieved, failed MoM, and TiN Coated devices. Electrochemical tests consisted of open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests conducted using the condylar head of the retrieved failed devices. EIS confirmed material properties as well as corrosion kinetics in vivo help to mitigate corrosion as reflected by the Raman spectroscopy results. In summary, this study demonstrated the role of wear and corrosion interactions on the early failure of TMJ TJR devices. Since the materials employed in most orthopedic TJR devices are similar to those used in TMJ TJR implants, studies such as this can provide data that will improve future embodiment paradigms for both. Further studies will include in vitro investigation of corrosion kinetics and the underlying tribocorrosion mechanism of TMJ TJR devices. STATEMENT OF SIGNIFICANCE: An attempt is made in this study, to examine the retrieved TMJ implants and conduct surface and electrochemical analysis; further a translation research approach is employed to compare the observations from the total hip replacement (THR) retrievals. A total cohort of 31 TMJ TJR devices were studied of which 28 were failed, retrieved TMJ TJRs, 3 were never implanted devices that served as controls. Data was acquired and evaluated by analyzing alloy microstructure. Substantial surface damage was observed between the articulating areas of the condylar head and the glenoid fossa components. Electrochemical analysis was performed on the MoM Control, retrieved, failed MoM, and TiN Coated devices. This study demonstrated the role of wear and corrosion interactions on the early failure of TMJ TJR devices. Since the materials employed in most orthopedic TJR devices are similar to those used in TMJ TJR implants, a comparison study was conducted.

The role of lipopolysaccharide on the electrochemical behavior of titanium.

UNLABELLED: Lipopolysaccharide (LPS) may induce peri-implantitis and implant failure. However, the role of LPS in titanium (Ti) electrochemical behavior remains unknown. We hypothesized that LPS in saliva with different pHs affects Ti corrosion properties. Thirty-six Ti discs (15 mm × 3 mm) were divided into 12 groups according to saliva pH (3, 6.5, and 9) and Escherichia coli LPS concentration (0, 0.15, 15, and 150 µg/mL). Electrochemical tests, such as open circuit potential, potentiodynamic, and electrochemical impedance spectroscopy, were conducted in a controlled environment. Data were evaluated by Pearson correlation and regression analysis (α = 0.05). LPS and pH affected Ti corrosive behavior. In general, lower pH and higher LPS concentration accelerated Ti corrosion. In the control group, the increase of pH significantly reduced the corrosion rate and increased the capacitance of the double layer. In LPS groups, the decrease of pH significantly increased the corrosion rate of Ti. LPS negatively influenced Ti corrosion behavior. ABBREVIATIONS: C(dl), capacitance of double layer; E(corr), corrosion potential; EIS, electrochemical impedance spectroscopy; I(corr), corrosion current density; I(pass), passivation current density; LPS, lipopolysaccharide; OCP, open circuit potential; R(p), polarization resistance; Ti, titanium.

Molecular cloning of wound inducible transcript (wit 3.0) differentially expressed in edentulous oral mucosa undergoing tooth extraction wound-healing.

Tooth extraction is the most commonly prescribed ablation surgery in dentistry and results in the formation of edentulous mucosa. Although the edentulous mucosa serves as the critical interfacial tissue for removable and implant-assisted prostheses, the structure and physiology of this wound-induced tissue are largely uninvestigated. We addressed the hypothesis that tooth extraction activates the expression of a unique set of genes in healing edentulous mucosa. Using the Differential Display Polymerase Chain Reaction and 5' Rapid Amplification of cDNA Ends protocols, we isolated overlapping cDNAs encoding a 3.0-kb-long mRNA, Wound Inducible Transcript, 3.0 (wit 3.0). In situ hybridization demonstrated that wit 3.0 was primarily expressed by the fibroblasts associated with tooth extraction wound-healing. Appearing to generate from the wit 3.0 gene, two alternative transcripts presented, encoding 215-(wit 3.0 alpha) and 253-(wit 3.0 beta) amino-acid-long peptides with the characteristics of an intracellular molecule. Analysis of these data may provide new clues to the molecular mechanism of edentulous mucosa formation.

Ovariectomy hinders the early stage of bone-implant integration: histomorphometric, biomechanical, and molecular analyses.

Postmenopausal osteoporosis is a contributing factor to alveolar bone atrophy associated with tooth loss in the elderly. The use of dental titanium implants has been increasingly adapted to treat these edentulous patients. This study examines whether female gonadal hormone deficiency interferes with the critical integration process between bone and implants. Two types of experimental titanium implants with acid-treated surfaces were placed in the femurs of ovariectomized (ovx) and sham-operated control rats: T-cell implants with a hollow chamber for histomorphometric and steady-state mRNA expression assays, and unthreaded cylindrical implants for biomechanical push-in tests. At week 2, less bone area was found in the ovx-implant group (p = 0.0495) than in the sham-implant group. The implant push-in test showed that the ovx-implant group had approximately half of the withstanding value of the sham-implant group (p = 0.009). However, these differences between the ovx and sham groups became diminished at week 4. Total RNA samples were examined by a reverse transcriptase-polymerase chain reaction assay for col1a1, col3a1, bone sialoprotein (bSP) II, osteonectin, osteopontin, osteocalcin, integrin beta1 and integrin beta3. In untreated bones and in created bone defects without implant placement, ovx did not affect the steady-state levels of the mRNAs tested. When implants were placed, significant upregulation of these genes was observed in the sham-implant group; however, only osteocalcin and integrins were upregulated in the ovx-implant group. The results suggest a biphasic effect of female gonadal hormone deficiency that may temporarily interfere with the early implant-tissue integration process, and which may be associated with a failure to upregulate a selected set of bone extracellular matrix genes. Once established, however, functional bone-implant integration can be achieved even in ovx rats.

Biomechanical evaluation of osseous implants having different surface topographies in rats.

Biomechanical and biological factors can co-dependently influence the establishment of implant-tissue integration; thus, concurrent evaluation of these factors should provide a better understanding of osseointegration. This study aimed to establish and validate an in vivo rat model frequently used in molecular/cellular biology for implant biomechanical studies. We tested the hypotheses that the implant push-in test assesses the degree of osseointegration by the breakpoint load at the implant-tissue interface and that it sensitively differentiates between the effects of different implant surface topographies. The implant push-in test, which produces a consistent load-displacement measurement, was used to test miniature cylindrical titanium implants placed at the distal edge of the adult rat femur. The push-in test values obtained at each post-implantation healing point (weeks 0, 2, 4, and 8) significantly increased in a time-dependent manner. The implant surface after the push-in test was associated with remnant tissues containing host-derived elements, such as calcium, phosphate, and sulfate. In this model, acid-etched implants (average roughness, 0.159 microm) showed significantly greater push-in test values than did turned implants (average roughness, 0.063 microm) throughout the experimental period (p < 0.0001). These results support the validity of the push-in test in rats, which may be used as a rapid and sensitive biomechanical assay system for implant osseointegration research.

Collagen XII mutation disrupts matrix structure of periodontal ligament and skin.

Collagen XII has been postulated to organize the extracellular matrix (ECM) architecture of dense connective tissues such as the periodontal ligament (PDL) and skin. The objective of this study was to test this hypothesis in transgenic mice carrying a dominant interference mutation of collagen XII. The truncated alpha1(XII) collagen minigene construct MXIINC3(-), driven by the mouse alpha2(I) collagen promoter, was prepared and used to generate transgenic mouse lines. The PDL matrix fibers of molar teeth lost the ordered architecture characteristic of ligament tissue without noticeable inflammation. Cellular cement appeared to be disrupted at the PDL insertion. By confocal laser scanning microscopy, the PDL of transgenic mice demonstrated swollen and irregularly arranged collagen fibers associated with internal porosity. The skin of transgenic mice revealed the lack of matrix fiber structure in the papillary dermis. These results indicated that the dominant interference mutation of collagen XII disorganized the ECM architecture of PDL and skin.