Faculty Bibliography

Societal changes, including the aging of the US population and the lack of routine dental service coverage under Medicare, have left many seniors unable to afford any dental care whatsoever, let alone the most advanced treatments.(1) In 2004, the Columbia University College of Dental Medicine and its partners instituted the ElderSmile program in the largely impoverished communities of Harlem and Washington Heights/Inwood in New York City. The long-term goal of this program is to improve access to and delivery of oral health care for seniors; the short-term goal is to establish and operate a network of prevention centers surrounding a limited number of treatment centers. Preliminary results indicate substantial unmet dental needs in this largely Hispanic and Black elderly population.

Clinically, zirconia-supported all-ceramic restorations are failing by veneer-chipping without exposing the zirconia interface. We hypothesized that mouth motion step-stress-accelerated fatigue testing of standardized dental crowns would permit this previously unrecognized failure mode to be investigated. Using CAD software, we imported the average dimensions of a mandibular first molar crown and modeled tooth preparation. The CAD-based tooth preparation was rapid-prototyped as a die for fabrication of zirconia core porcelain-veneered crowns. Crowns were bonded to aged composite reproductions of the preparation and aged 14 days in water. Crowns were single-cycle-loaded to failure or mouth-motion step-stress- fatigue-tested. Finite element analysis indicated high stress levels below the load and at margins, in agreement with only single-cycle fracture origins. As hypothesized, the mouth motion sliding contact fatigue resulted in veneer chipping, reproducing clinical findings allowing for investigations into the underlying causes of such failures

BACKGROUND: The tear trough and the lid/cheek junction become more visible with age. These landmarks are adjacent, forming in some patients a continuous indentation or groove below the infraorbital rim. Numerous, often conflicting procedures have been described to improve the appearance of the region. The purpose of this study was to evaluate the anatomy underlying the tear trough and the lid/cheek junction and to evaluate the procedures designed to correct them. METHODS: Twelve fresh cadaver lower lid and midface dissections were performed (six heads). The orbital regions were dissected in layers, and medical photography was performed. RESULTS: In the subcutaneous plane, the tear trough and lid/cheek junction overlie the junction of the palpebral and orbital portions of the orbicularis oculi muscle and the cephalic border of the malar fat pad. In the submuscular plane, these landmarks differ. Along the tear trough, the orbicularis muscle is attached directly to the bone. Along the lid/cheek junction, the attachment is ligamentous by means of the orbicularis retaining ligament. CONCLUSIONS: The tear trough and lid/cheek junction are primarily explained by superficial (subcutaneous) anatomical features. Atrophy of skin and fat is the most likely explanation for age-related visibility of these landmarks. 'Descent' of this region with age is unlikely (the structures are fixed to bone). Bulging orbital fat accentuates these landmarks. Interventions must extend significantly below the infraorbital rim. Fat or synthetic filler may be best placed in the intraorbicularis plane (tear trough) and in the suborbicularis plane (lid/cheek junction)

This article presents details of processing, characterization and in vitro as well as in vivo evaluations of powder metallurgy processed Ti-13Nb-13Zr samples with different levels of porosity. Sintered samples were characterized for density, crystalline phases (XRD), and microstructure (SEM and EDX). Samples sintered at 1000 degrees C showed the highest porosity level ( approximately 30%), featuring open and interconnected pores ranging from 50 to 100 mum in diameter but incomplete densification. In contrast, samples sintered at 1300 and 1500 degrees C demonstrated high densification with 10% porosity level distributed in a homogeneous microstructure. The different sintering conditions used in this study demonstrated a coherent trend that is increase in temperature lead to higher sample densification, even though densification represents a drawback for bone ingrowth. Cytotoxicity tests did not reveal any toxic effects of the starting and processed materials on surviving cell percentage. After an 8-week healing period in rabbit tibias, the implants were retrieved, processed for nondecalcified histological evaluation, and then assessed by backscattered electron images (BSEI-SEM) and EDX. Bone growth into the microstructure was observed only in samples sintered at 1000 degrees C. Overall, a close relation between newly formed bone and all processed samples was observed.

PURPOSE: In an attempt to overcome the potential long-term limitations observed with plasma-sprayed hydroxyapatite-coated implants, nanothickness bioceramic coatings have been processed onto previously grit-blasted/acid-etched surfaces. Our objective was to evaluate the bone response to alumina-blasted/acid-etched and a thin ion beam-deposited bioceramic (Test) implant surfaces at 2 and 4 weeks in vivo with a dog tibia model. MATERIALS AND METHODS: Plateau root form implants (5 x 6 mm) were placed bilaterally along the proximal tibia of 6 Doberman dogs and remained for 2 and 4 weeks in vivo (n=6 per implant type and time in vivo). After euthanization, the implants were processed in a nondecalcified form and reduced to approximately 30 mum-thickness plates. Transmitted light optical microscopy at various magnifications was used to qualitatively evaluate the bone healing patterns. Bone-to-implant contact (BIC) was determined and 1-way ANOVA at 95% level of significance with Tukey's post-hoc multiple comparisons was used for statistical analysis. RESULTS: Histomorphology showed new bone formation filling the spaces between the plateaus at both in vivo time intervals through large quantities of woven bone formation. A higher degree of bone organization was observed between the plateaus of Test implants at 4 weeks in vivo than the alumina-blasted/acid-etched implants. No significant differences in BIC were observed for the different groups (P> .86). CONCLUSION: Despite nonsignificant differences between BIC for the different implant surfaces and times in vivo, higher degrees of bone organization were observed for the Test implants at 4 weeks, and biomechanical testing is suggested to verify its biomechanical fixation effectiveness.

Classic tissue engineering paradigms are limited by the incorporation of a functional vasculature and a reliable means for reimplantation into the host circulation. We have developed a novel approach to overcome these obstacles using autologous explanted microcirculatory beds (EMBs) as bioscaffolds for engineering complex three-dimensional constructs. In this study, EMBs consisting of an afferent artery, capillary beds, efferent vein, and surrounding parenchymal tissue are explanted and maintained for 24 h ex vivo in a bioreactor that preserves EMB viability and function. Given the rapidly advancing field of stem cell biology, EMBs were subsequently seeded with three distinct stem cell populations, multipotent adult progenitor cells (MAPCs), and bone marrow and adipose tissue-derived mesenchymal stem cells (MSCs). We demonstrate MAPCs, as well as MSCs, are able to egress from the microcirculation into the parenchymal space, forming proliferative clusters. Likewise, human adipose tissue-derived MSCs were also found to egress from the vasculature and seed into the EMBs, suggesting feasibility of this technology for clinical applications. We further demonstrate that MSCs can be transfected to express a luciferase protein and continue to remain viable and maintain luciferase expression in vivo. By using the vascular network of EMBs, EMBs can be perfused ex vivo and seeded with stem cells, which can potentially be directed to differentiate into neo-organs or transfected to replace failing organs and deficient proteins

BACKGROUND: Nasoalveolar molding was developed to improve dentoalveolar, septal, and lower lateral cartilage position before cleft lip repair. Previous studies have documented the long-term maintenance of columella length and nasal dome form and projection. The purpose of the present study was to determine the effect of presurgical nasoalveolar molding on long-term unilateral complete cleft nasal symmetry. METHODS: A retrospective review of 25 consecutively presenting nonsyndromic complete unilateral cleft lip-cleft palate patients was conducted. Fifteen patients were treated with presurgical nasoalveolar molding for 3 months before surgical correction, and 10 patients were treated by surgical correction alone. The average age at the time of follow-up was 9 years. Four nasal anthropometric distances and two angular relationships were measured to assess nasal symmetry. RESULTS: All six measurements demonstrated a greater degree of nasal symmetry in nasoalveolar molding patients compared with the patients treated with surgery alone. Five symmetry measurements were significantly more symmetric in the nasoalveolar molding patients and one measurement demonstrated a nonsignificant but greater degree of symmetry compared with the patients treated with surgery alone. CONCLUSIONS: The data demonstrate that the lower lateral and septal cartilages are more symmetric in the nasoalveolar molding patients compared with the surgery-alone patients. Furthermore, the improved symmetry observed in nasoalveolar molding-treated noses during the time of the primary surgery is maintained at 9 years of age

BACKGROUND: Population-based overall patterns of surgical management of the axilla in women with operable breast cancer during the era of adoption of sentinel lymph node biopsy (SLNB) were studied. METHODS: Women with operable breast carcinoma residing in 14 geographic areas of the Surveillance, Epidemiology, and End Results (SEER) cancer registries (1998-2004, n=239,661) were assessed for axillary surgical patterns of care. RESULTS: Use of SLNB increased from 11 to 59%. Use of no axillary surgery decreased from 14 to 6.6%. In pathologic node-negative women, use of axillary lymph node dissection (ALND) decreased from 94 to 36%. Independent factors most associated with failure to receive SLNB included diagnosis year (2000: 62%; 2004: 29%), surgery (mastectomy: 64%; breast-conserving surgery: 36%), tumor size (T3: 71%; T2: 56%; T1: 40%), age (>or= 70 years: 50%; <70 years: 45%), grade (high: 42%; low: 38%), urbanity (non-large metropolitan area: 49%; large metropolitan area: 42%), and, by quartile, poverty (highest: 47%; lowest: 35%), and white-collar employment (lowest: 56%; highest: 47%). In pathologic node-positive women who had SLNB, failure to undergo completion ALND increased from 20% in 1998 to 32% in 2004. Patients with smaller, lower-grade tumors, and those with smaller size of nodal metastasis, lack of extracapsular extension, age >or= 70 years, increased linguistic isolation, African-American or Hispanic race/ethnicity, and white-collar employment were less likely to undergo completion ALND. CONCLUSIONS: Management of the axilla changed dramatically during the period of rapid adoption of SLNB. Patterns of care suggest both appropriate and inappropriate selection for SLNB and ALND

BACKGROUND: The cross-facial nerve grafting/free-muscle transfer strategy for smile restoration is superior to static reconstruction or regional muscle transposition. The purpose of this study was to evaluate the long-term outcomes of this technique in adult patients. METHODS: Eighty-one adult patients received a free-muscle transfer for midface reanimation in the authors' center. Of this group, the authors identified 24 cases with follow-up of 5 years or longer. Smile symmetry and function were evaluated at three points: preoperatively, early postoperatively, and at long-term follow-up. To better evaluate the effect of time, patients were divided into groups according to 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. Four independent observers rated each patient's smile using a five-category scale ranging from poor to excellent. Panelists were asked to comment on whether the patient's smile weakened over time. RESULTS: All patients obtained higher scores at 2 years from free-muscle transfer in comparison with their preoperative rates (p < 0.0001). Late outcomes demonstrated that muscle regeneration continues beyond the initial 2 years, with a further increase of the scores and motor units on electromyography at the late follow-up (p < 0.0001, p = 0.0313). No significance was found when comparing both variables among the four groups, indicating that time does not have a differential effect on muscle function. In 80 percent of the evaluations, the four observers agreed on maintained smile symmetry over time. CONCLUSIONS: Cross-facial nerve grafting/free-muscle transfer is an effective technique for smile restoration in late facial paralysis. These data indicate maintenance of effective muscle function and progressive improvement with time