Faculty Bibliography

Purpose: To investigate the reliability of titanium abutments veneered with indirect composites for implant-supported crowns and the possibility to trace back the fracture origin by qualitative fractographic analysis. Materials and Methods: Large base (LB) (6.4-mm diameter base, with a 4-mm high cone in the center for composite retention), small base (SB-4) (5.2-mm base, 4-mm high cone), and small base with cone shortened to 2 mm (SB-2) Ti abutments were used. Each abutment received incremental layers of indirect resin composite until completing the anatomy of a maxillary molar crown. Step-stress accelerated-life fatigue testing (n = 18 each) was performed in water. Weibull curves with use stress of 200 N for 50,000 and 100,000 cycles were calculated. Probability Weibull plots examined the differences between groups. Specimens were inspected in light-polarized and scanning electron microscopes for fractographic analysis. Results: Use level probability Weibull plots showed Beta values of 0.27 for LB, 0.32 for SB-4, and 0.26 for SB-2, indicating that failures were not influenced by fatigue and damage accumulation. The data replotted as Weibull distribution showed no significant difference in the characteristic strengths between LB (794 N) and SB-4 abutments (836 N), which were both significantly higher than SB-2 (601 N). Failure mode was cohesive within the composite for all groups. Fractographic markings showed that failures initiated at the indentation area and propagated toward the margins of cohesively failed composite. Conclusions: Reliability was not influenced by abutment design. Qualitative fractographic analysis of the failed indirect composite was feasible.

Nanostructure modification of dental implants has long been sought as a means to improve osseointegration through enhanced biomimicry of host structures. Several methods have been proposed and demonstrated for creating nanotopographic features; here we describe a nanoscale hydroxyapatite (HA)-coated implant surface and hypothesize that it will hasten osseointegration and improve its quality relative to that of non-coated implants. Twenty threaded titanium alloy implants, half prepared with a stable HA nanoparticle surface and half grit-blasted, acid-etched, and heat-treated (HT), were inserted into rabbit femurs. Pre-operatively, the implants were morphologically and topographically characterized. After 3 weeks of healing, the samples were retrieved for histomorphometry. The nanomechanical properties of the surrounding bone were evaluated by nanoindentation. While both implants revealed similar bone-to-implant contact, the nanoindentation demonstrated that the tissue quality was significantly enhanced around the HA-coated implants, validating the postulated hypothesis.

BACKGROUND: : Free tissue transfer to improve bulk and contour in facial deformities has been proven useful, yet refinements that turn an acceptable result into an excellent result are essential to reconstruction. The authors reviewed their experience and described these refinements. METHODS: : The charts of 371 free tissue transfer cases (1989 to 2010) performed by the senior author (J.W.S.) were reviewed. Free tissue transfer of a circumflex scapular variant flap or superficial inferior epigastric was performed to treat deformities arising from hemifacial atrophy (n = 126), hemifacial microsomia (n = 89), radiation therapy (n = 40), bilateral malformations including lupus and polymyositis (n = 50), other congenital anomalies (n = 25), facial palsy (n = 17), and burns and trauma (n = 24). RESULTS: : Revision surgery planning began at initial flap operation where the flap was stretched maximally and interdigitated with recipient tissue. More tissue was required in the malar region. Revision refinement was indicated in all cases (after 6 months). Flap revision involved liposuction, debulking, reelevation, and release of tethering, followed by tissue rearrangement by means of advancement, rotation, transposition, and/or turnover flaps of subcutaneous tissues from the previous free flap. The jawline frequently required more debulking. Periorbital reconstruction was combined with lower lid support with or without canthal repositioning. Conventional face-lift techniques with the flap as superficial musculoaponeurotic system augmented the result. Autologous fat injection to the alar rim, medial canthus, upper eyelid, and lip was a useful adjunct. Severe lip deficiencies were addressed with local flaps. CONCLUSION: : The keys to improving results were continual critical reassessment, open-mindedness to new approaches, and maintaining high expectations. CLINICAL QUESTION/LEVEL OF EVIDENCE: : Therapeutic, V.

BACKGROUND: : The graying of our population has motivated the authors to better understand age-related impairments in wound healing. To increase research throughput, the authors hypothesized that the Hutchinson-Gilford progeria syndrome Zmpste24-deficient (Zmpste24) mouse could serve as a model of senescent wound healing. METHODS: : Using a stented excisional wound closure model, the authors tested this hypothesis on 8-week-old male Zmpste24 mice (n = 25) and age-matched male C57BL/6J wild-type mice (n = 25). Wounds were measured photogrammetrically and harvested for immunohistochemistry, enzyme-linked immunosorbent assay, and quantitative real-time polymerase chain reaction, and circulating vasculogenic progenitor cells were measured by flow cytometry. RESULTS: : Zmpste24 mice had a significant delay in wound closure compared with wild-type mice during the proliferative/vasculogenic phase. Zmpste24 wounds had decreased proliferation, increased 8-hydroxy-2'-deoxyguanosine levels, increased proapoptotic signaling (i.e., p53, PUMA, BAX), decreased antiapoptotic signaling (i.e., Bcl-2), and increased DNA fragmentation. These changes correlated with decreased local vasculogenic growth factor expression, decreased mobilization of bone marrow-derived vasculogenic progenitor cells, and decreased new blood vessel formation. Age-related impairments in wound closure are multifactorial. CONCLUSIONS: : The authors' data suggest that the Hutchinson-Gilford progeria syndrome Zmpste24 progeroid syndrome shares mechanistic overlap with normal aging and therefore might provide a uniquely informative model with which to study age-associated impairments in wound closure.

OBJECTIVES/HYPOTHESIS: To evaluate reconstructive outcomes following oncologic temporal bone resection. STUDY DESIGN: Retrospective review. METHODS: Subjects consisted of 117 patients undergoing temporal bone resection and reconstruction between 2000 and 2010. Reconstructive outcomes, including results following facial nerve repair, were analyzed. RESULTS: Reconstruction was performed with a regional flap in 27 patients and a microvascular free flap in 90 patients. Operative time was shorter for cases involving reconstruction with regional flaps compared to free flaps (6.9 vs. 11.2 hours, P < .0001), as were intensive care unit and hospital stays (0.4 vs. 3.4 days, P < .0001 and 4.1 vs. 8.6 days, P < .0001, respectively). Overall complication rates were similar for regional and free flap cases (22.2% vs. 23.3%, P = 1.00), although donor site complications were more common with free flaps (0% vs. 13.3%, P = .07). Facial nerve repairs were performed in 19 patients. Of 14 patients with more than 12 months of follow-up, 71.4% demonstrated signs of reinnervation and 42.9% achieved a House-Brackmann score of 3 or better. The mean time to reinnervation was 7.9 months. Recovery was not significantly affected by preoperative nerve function, postoperative radiation, or advanced age (P = 1.00 in each case). CONCLUSIONS: We recommend regional flaps for small defects based on minimal donor site morbidity, and shorter operative times, intensive care unit, and hospital stays. For extensive defects and in cases involving prior surgery or radiation, free flaps are preferred. Facial nerve repair should be attempted whenever feasible, even in the setting of preoperative weakness, planned postoperative radiation, and advanced age.

Study purposes were to determine the prevalence of persistent pain in the breast; characterize distinct persistent pain classes using growth mixture modeling; and evaluate for differences among these pain classes in demographic, preoperative, intraoperative, and postoperative characteristics. In addition, differences in the severity of common symptoms and quality of life outcomes measured prior to surgery, among the pain classes, were evaluated. Patients (n = 398) were recruited prior to surgery and followed for 6 months. Using growth mixture modeling, patients were classified into no (31.7%), mild (43.4%), moderate (13.3%), and severe (11.6%) pain groups based on ratings of worst breast pain. Differences in a number of demographic, preoperative, intraoperative, and postoperative characteristics differentiated among the pain classes. In addition, patients in the moderate and severe pain classes reported higher preoperative levels of depression, anxiety, and sleep disturbance than the no pain class. Findings suggest that approximately 25% of women experience significant and persistent levels of breast pain in the first 6 months following breast cancer surgery. PERSPECTIVE: Persistent pain is a significant problem for 25% of women following surgery for breast cancer. Severe breast pain is associated with clinically meaningful decrements in functional status and quality of life.

The primary stability of dental implants has been investigated before, but a study of the influence of implant shape, size and surface morphology (machined, acid etched or anodized), surgical technique (press-fit or undersized) and substrate (natural or simulated bone) on the primary stability of dental implants has not been reported. The present work intends to fill this gap. In this work, six different dental implants were inserted into and removed from synthetic and natural bone while measuring the torque. A total of 255 dental implants with three shapes, four sizes and three surface topographies were inserted into pig rib, PTFE and polyurethane. The implant sites were prepared using straight and tapered drills. The primary stability was estimated from the maximum insertion torque. Comparisons between samples were based on the maximum insertion torque (MIT), the maximum removal torque (MRT) and the torque ratio (TR=MRT/MIT). The insertion torque into pig ribs showed larger dispersion. All parameters (shape, size and surface morphology of the implant, surgical technique and substrate type) were found to have a significant influence on primary stability. The insertion of a tapered implant requires a higher torque than the insertion of a straight implant. Surface treatments improve the primary stability. The influence of the surgical technique is smaller than that of implant size and shape. The highest insertion torque was that of anodized tapered implants inserted into undersized sites. Finally, the primary stability of dental implants is highly dependent on implant design, surgical technique and substrate type.

STATEMENT OF PROBLEM: Currently, there is no commercially available method to provide non-invasive, non-ionizing, real-time imaging of the gingival form and bony architecture of implant sites, before, during, and after implant placement. PURPOSE: The purpose of this study was to demonstrate the feasibility of 2-dimensional (2-D) ultrasound imaging of soft and hard tissues for implant diagnosis and treatment planning. MATERIAL AND METHODS: A sector scanning ultrasound system was applied. Five representative clinical features (implant in an edentulous ridge, single implant tooth replacement, implant dehiscence, tooth dehiscence, and mental foramina) were created or identified in each of the 5 porcine jaws, which were then covered with soft tissue and imaged in an acoustic water tank. RESULTS: All of the 5 model features, in all 5 jaws, were clearly visible with the ultrasound. Most objects were visible over a large range of positions and angles. Each of the features, as well as the soft tissue and bone surfaces, were recognized by specific acoustic signatures, with the same signature recurring for each object type among all 5 of the jaw specimens. All implants were highly reflective and clearly visualized. CONCLUSIONS: A 2-D sector scanning ultrasound system was demonstrated to be capable of imaging representative features for implant treatment planning in a porcine model; these included implants placed in edentulous ridges; implants placed for single tooth replacement; implants with simulated dehiscences; teeth with simulated dehiscences; and mental foramina. Specific acoustic signatures for these features were defined. Qualitative differences between ultrasound and other dental imaging techniques were described.