Faculty Bibliography

OBJECTIVE: This work aims to present a pilot study of a non-destructive dental histo-anatomical analysis technique as well as to push the boundaries of the presently available restorative workflows for the fabrication of highly customized ceramic restorations. MATERIALS AND METHODS: An extracted human maxillary central incisor was subject to a micro computed tomography scan and the acquired data was transferred into a workstation, reconstructed, segmented, evaluated and later imported into a Computer-Aided Design/Computer-Aided Manufacturing software for the fabrication of a ceramic resin-bonded prosthesis. RESULTS: The obtained prosthesis presented an encouraging optical behavior and was used clinically as final restoration. CONCLUSION: The digitally layered restorative replication of natural tooth morphology presents today as a clear possibility. New clinical and laboratory-fabricated, biologically inspired digital restorative protocols are to be expected in the near future. CLINICAL SIGNIFICANCE: The digitally layered restorative replication of natural tooth morphology presents today as a clear possibility. This pilot study may represent a stimulus for future research and applications of digital imaging as well as digital restorative workflows in service of esthetic dentistry.

PURPOSE: To assess the probability of survival (reliability) and failure modes of narrow implants with different diameters. MATERIALS AND METHODS: For fatigue testing, 42 implants with the same macrogeometry and internal conical connection were divided, according to diameter, as follows: narrow (O3.3x10mm) and extra-narrow (O2.9x10mm) (21 per group). Identical abutments were torqued to the implants and standardized maxillary incisor crowns were cemented and subjected to step-stress accelerated life testing (SSALT) in water. The use-level probability Weibull curves, and reliability for a mission of 50,000 and 100,000 cycles at 50N, 100, 150 and 180N were calculated. For the finite element analysis (FEA), two virtual models, simulating the samples tested in fatigue, were constructed. Loading at 50N and 100N were applied 30 degrees off-axis at the crown. The von-Mises stress was calculated for implant and abutment. RESULTS: The beta (beta) values were: 0.67 for narrow and 1.32 for extra-narrow implants, indicating that failure rates did not increase with fatigue in the former, but more likely were associated with damage accumulation and wear-out failures in the latter. Both groups showed high reliability (up to 97.5%) at 50 and 100N. A decreased reliability was observed for both groups at 150 and 180N (ranging from 0 to 82.3%), but no significant difference was observed between groups. Failure predominantly involved abutment fracture for both groups. FEA at 50N-load, O3.3mm showed higher von-Mises stress for abutment (7.75%) and implant (2%) when compared to the O2.9mm. CONCLUSIONS: There was no significant difference between narrow and extra-narrow implants regarding probability of survival. The failure mode was similar for both groups, restricted to abutment fracture.

OBJECTIVES/HYPOTHESIS: Quantification of clinical outcomes after vocal fold (VF) interventions is challenging with current technology. High-speed digital imaging and optical coherence tomography (OCT) of excised larynges assess intact laryngeal function, but do not provide critical biomechanical information. We developed a protocol to quantify tissue properties in intact, excised VFs using dynamic nanomechanical analysis (nano-DMA) to obtain precise biomechanical properties in the micrometer scale. STUDY DESIGN: Experimental animal study. METHODS: Three pig larynges were bisected in the sagittal plane, maintaining an intact anterior commissure, and subjected to nano-DMA at nine locations with a 250-mum flat-tip punch and frequency sweep load profile (10-105 Hz, 1,000 muN peak force) across the free edge of the VF and inferiorly along the conus elasticus. RESULTS: Storage, loss, and complex moduli increased inferiorly from the free edge. Storage moduli increased from a mean of 32.3 kPa (range, 6.5-55.38 kPa) at the free edge to 46.3kPa (range, 7.4-71.6) 5 mm below the free edge, and 71.4 kPa (range, 33.7-112 kPa) 1 cm below the free edge. Comparable values were 11.6 kPa (range, 5.0-20.0 kPa), 16.7 kPa (range, 5.7-26.8 kPa), and 22.6 kPa (range, 9.7-38.0 kPa) for loss modulus, and 35.7 kPa (range, 14.4-56.4 kPa), 50.1 kPa (range, 18.7-72.8 kPa), and 75.4 kPa (range, 42.0-116.0 kPa) for complex modulus. Another larynx repeatedly frozen and thawed during technique development had similarly increased storage, loss, and complex modulus trends across locations. CONCLUSIONS: Nano-DMA of the intact hemilarynx provides a platform for quantification of biomechanical responses to a myriad of therapeutic interventions to complement data from high-speed imaging and OCT. LEVEL OF EVIDENCE: NA Laryngoscope, 2016.

OBJECTIVE: To evaluate the effect of light-curing wavelengths on composite filler particle displacement, and thus to visualize localized polymerization shrinkage in a resin-based composite (RBC) containing camphorquinone (CQ) and Lucirin TPO (TPO). METHODS: Three light-curing units (LCUs) were used to light-cure a RBC containing CQ and TPO: a violet-only, a blue-only, and a dual-wavelength, conventional (Polywave(R), emitting violet and blue wavelengths simultaneously). Zirconia fillers were added to the RBC to act as filler particle displacement tracers. LCUs were characterized for total emitted power (mW) and spectral irradiant output (mW/cm2/nm). 2-mm high, 7-mm diameter silanized glass cylindrical specimens were filled in a single increment with the RBC, and micro-computed tomography (mu-CT) scans were obtained before and after light-curing, according to each LCU (n=6). Filler particle movement identified polymerization shrinkage vectors, traced using software, at five depths (from 0 up to 2mm): top, top-middle, middle, middle-bottom and bottom. RESULTS: Considering different RBC depths within the same LCU, use of violet-only and conventional LCUs showed filler particle movement decreased with increased depth. Blue-only LCU showed homogeneous filler particle movement along the depths. Considering the effect of different LCUs within the same depth, filler particle movement within LCUs was not statistically different until the middle of the samples (P>.05). However, at the middle-bottom and bottom depths (1.5 and 2mm, respectively), blue-only LCU compared to violet-only LCU showed higher magnitude of displacement vector values (P<.05). Use of the conventional LCU showed filler displacement magnitudes that were not significantly different than blue-only and violet-only LCUs at any depth (P>.05). With respect to the direction of particle movement vectors, use of violet-only LCU showed a greater displacement when close to the incident violet LED; blue-only LCU showed equally distributed particle displacement values within entire depth among the samples; and the conventional LCU showed greater filler displacement closer to the blue LED locations. SIGNIFICANCE: Filler particle displacement in a RBC as a result of light-curing is related to localized application of light wavelength and total emitted power of the light emitted on the top surface of the RBC. When the violet LED is present (violet-only and conventional LCUs), filler particle displacement magnitude decreased with increased depth, while results using the blue-only LED show a more consistent pattern of displacement. Clinically, these results correlate to production of different characteristics of curing within a RBC restoration mass, depending on localized wavelengths applied to the irradiated surface.

STATEMENT OF PROBLEM: Few studies have investigated the volumetric polymerization shrinkage and film thickness of the different cementation techniques used to cement veneers. PURPOSE: The purpose of this in vitro study was to evaluate the volumetric polymerization shrinkage (VS) and film thickness (FT) of various cementation techniques through 3-dimensional (3D) microcomputed tomography (muCT). MATERIAL AND METHODS: Forty-eight artificial plastic maxillary central incisors with standard preparations for veneers were provided by a mannequin manufacturer (P-Oclusal) and used as testing models with the manufacturer's plastic veneers. They were divided into 8 groups (n=6): RelyX Veneer + Scotchbond Universal (RV+SBU); Variolink Esthetic LC+Adhese Universal (VE+ADU); Filtek Supreme Ultra Flowable + Scotchbond Universal (FF+SBU); IPS Empress Direct Flow + Adhese Universal (IEF+ADU); Filtek Supreme Ultra Universal + Scotchbond Universal (FS+SBU); IPS Empress Direct + Adhese Universal (IED+ADU); Preheated Filtek Supreme Ultra Universal + Scotchbond Universal (PHF+SBU); and Preheated IPS Empress Direct + Adhese Universal (PHI+ADU). Specimens were scanned before and after polymerization using a muCT apparatus (mCT 40; Scanco Medical AG), and the resulting files were imported and analyzed with 3D rendering software to calculate the VS and FT. Collected data from both the VS and FT were submitted to 1-way ANOVA (alpha=.05). RESULTS: VE+ADU had the lowest volumetric shrinkage (1.03%), which was not significantly different from RV+SBU, FF+SBU or IEF+ADU (P>.05). The highest volumetric shrinkage was observed for FS+SBU (2.44%), which was not significantly different from RV+SBU, IED+ADU, PHF+SBU, or PHI+ADU (P>.05). Group RV+SBU did not differ statistically from the remaining groups (P>.05). Film thickness evaluation revealed the lowest values for RV+SBU, VE+ADU, FF+SBU, and IEF+ADU, with an average between groups of 0.17 mm; these groups were significantly different from FS+SBU, IED+ADU, PHF+SBU, and PHI+ADU (P>.05), with an average of 0.31 mm. CONCLUSIONS: Both the VS and the FT of direct restorative composite resins were higher than those of veneer cements and flowable composite resins, whether preheated or not preheated.

PURPOSE: Currently, surgeons approach autogenous microtia repair by creating a two-dimensional (2D) tracing of the unaffected ear to approximate a three-dimensional (3D) construct, a difficult process. To address these shortcomings, this study introduces the fabrication of patient-specific, sterilizable 3D printed auricular model for autogenous auricular reconstruction. METHODS: A high-resolution 3D digital photograph was captured of the patient's unaffected ear and surrounding anatomic structures. The photographs were exported and uploaded into Amira, for transformation into a digital (.stl) model, which was imported into Blender, an open source software platform for digital modification of data. The unaffected auricle as digitally isolated and inverted to render a model for the contralateral side. The depths of the scapha, triangular fossa, and cymba were deepened to accentuate their contours. Extra relief was added to the helical root to further distinguish this structure. The ear was then digitally deconstructed and separated into its individual auricular components for reconstruction. The completed ear and its individual components were 3D printed using polylactic acid filament and sterilized following manufacturer specifications. RESULTS: The sterilized models were brought to the operating room to be utilized by the surgeon. The models allowed for more accurate anatomic measurements compared to 2D tracings, which reduced the degree of estimation required by surgeons. Approximately 20 g of the PLA filament were utilized for the construction of these models, yielding a total material cost of approximately $1. CONCLUSION: Using the methodology detailed in this report, as well as departmentally available resources (3D digital photography and 3D printing), a sterilizable, patient-specific, and inexpensive 3D auricular model was fabricated to be used intraoperatively. This technique of printing customized-to-patient models for surgeons to use as 'guides' shows great promise.

OBJECTIVE: This study evaluated the osseointegration of commercially pure titanium (Ti) grade-2 (G2) and Ti-6Al-4V alloy (G5) implants with the same geometry and surface treatment. MATERIALS AND METHODS: Thirty-six dental implants with a grit-blasted acid-etched surface were used (n = 18, each). Two implants, one per group, were installed in each subject, in the radius diaphysis (n = 18 beagle dogs), with interchanged fixture position (proximal-distal) between animals for a balanced number of devices per group and time in vivo (1, 3, and 6 weeks). RESULTS: Similar topographical parameters between G2 and G5 were observed for average surface roughness, root mean square, developed surface ratio, maximum height of surface, and density of summits. Removal torque was significantly higher for G5 than for G2. No differences were observed for bone-to-implant contact and bone-area-fraction occupancy. Removal torque significantly increased with time for both groups. At 1 week, new bone formation in direct contact with the implant surface and osteogenic tissue migration was observed with an increase in woven bone formation at 3 weeks followed by the onset of lamellar bone formation at 6 weeks. CONCLUSION: Although both surfaces were biocompatible and osteoconductive, increased removal torque was observed for Ti-6Al-4V compared with commercially pure Ti implants.

Background/Purpose: Autogenous ear reconstruction remains one of the most technically challenging procedures in plastic surgery. Current methods to autogenous ear construct design entail tracing the contralateral (unaffected) ear, if available, and using this 2 dimensional outline as a surgical model. This study explores the feasibility of creating in-house patient specific intraoperative 3D models of autogenous ear reconstruction. Methods/Description: A 3 dimensional photograph of the unaffected ear (3DMD, Atlanta, GA) of a patient with unilateral microtia was uploaded into Amira (FEI Company, Hillsboro, Oregon, USA) and transformed to a (.stl) digital model. After rendering the (.stl) model of the ear, it was imported into Blendere (Amsterdam, The Netherlands) where it was inverted along the vertical axis to create a working template of the contralateral ear. The depths of the scapha, triangular fossa and cymba were all deepened to accentuate these contours. Additional relief was added to the helical root to further define this structure. The final template was digitally separated to create the requisite auricular components for the Nagata technique reconstruction: helix; antihelical fold with the superior and inferior crus; base frame. The patient had an intact tragus. The helix was digitally straightened to optimize its use as a model. The complete auricular model and the separated auricular components were all individually 3D printed (Builder Premium 3D Printer, Noordwijkerhout, The Netherlands) using a polylactic acid filament and sterilized following the manufacturer's specifications (1218C for 1 hour and 30 minute dry cycle). Results: The total time of digital preparation was 5 hours. Total time of 3D printing was 5.5 hours. Total cost of manufacturing was $0.78. On the day of surgery these sterilized, patient-specific 3 dimensional models were brought to the operating room and placed on the back table with the ear sculpting tools and carving block. The sterilized models were placed on the cartilage grafts and the forms and relief of the cartilage construct was easily appreciated and incorporated into the cartilage shape. Compared to the classic auricular tracings also present during this surgery these 3D printed models contained more detailed anatomic information which eliminated much of the guesswork from auricular reconstruction and resulted in a more efficient and precise operation. Conclusions: Leveraging hardware, expertise and software platforms already existing within an academic medical center, affordable, sterilizable, patient-specific 3D auricular models can be manufactured and used during autogenous ear construction

PURPOSE: The present study hypothesized that different bone healing patterns through initial stages of osseointegration would be observed when three distinct commercially available implant systems (Nobel Groovy, Implacil, and Zimmer TSV) were used, leading to significant variations in histometric levels of total bone and new bone formation during the osseointegration process. MATERIALS AND METHODS: A total of 48 implants were placed bilaterally on the tibias of eight beagle dogs and allowed to heal for 2 and 6 weeks. Following euthanasia, nondecalcified specimens were processed for morphologic and histometric evaluation. Bone-to-implant contact (BIC) and new bone area fraction occupancy (BAFO) analyses for native and new bone were performed along the whole perimeter of each implant and separately for the cortical and trabecular bone regions. RESULTS: Morphologic evaluation of cortical bone presented different healing patterns and osseointegration levels for different implant systems as time elapsed in vivo. Interfacial remodeling was the chief healing pattern in Zimmer implants, while a combination of interfacial remodeling and healing chambers was observed in Nobel and Implacil implants. When trabecular bone was evaluated, similar bone healing patterns were observed between systems despite different levels of osseointegration observed as a function of implantation time, implant system, and native and/or new bone BIC and BAFO. CONCLUSION: Different implant systems led to different healing patterns during early stages of osseointegration. Such variation in pattern was more noticeable in the cortical regions compared to the trabecular regions. The variation in bone healing pattern did significantly influence overall indicators of native and new BIC and BAFO during the osseointegration process. The postulated hypothesis was accepted.

PURPOSE: To investigate the influence of different materials and fixation methods on maximum principal stress (MPS) and displacement in reconstruction plates using in silico 3-dimensional finite element analysis (3D-FEA). MATERIALS AND METHODS: Computer-assisted designed (CAD) models of the mandible and teeth were constructed. Champy and AO/ASIF plates and fixation screws were designed with CAD software. 3D-FEA was performed by image-based CAE software. Maximum and minimum values of biomechanical stability, MPS, and displacement distribution were compared in Champy and AO/ASIF plates made from commercially pure titanium grade 2 (cp-Ti) and a titanium-and-molybdenum (14.47% wt) alloy (Ti-15Mo). RESULTS: For plates fixed on a model of a fractured left angle of the mandible, the maximum and minimum values of MPS in the cp-Ti-constructed Champy plate, upper AO/ASIF plate, and lower AO/ASIF plate were 19.5 and 20.3%, 15.2 and 25.3%, and 21.4 and 4.6% lower, respectively, than those for plates made from Ti-15Mo. In the same model, the maximum and minimum values of displacement in the cp-Ti-constructed Champy plate, upper AO/ASIF plate, and lower AO/ASIF plate were 1.6 and 3.8%, 3.1 and 2.7%, and 5.4 and 10.4% higher, respectively, than those for plates made from Ti-15Mo. CONCLUSIONS: This in silico 3D-FEA shows that Ti-15Mo plates have greater load-bearing capability.