Faculty Bibliography

The indications for free muscle transfer in brachial plexopathies are prolonged denervation time or inadequate upper extremity function after primary nerve reconstruction. The purpose of this study is to analyze the outcomes of free muscle transfer for elbow flexion and extension in brachial plexopathies in relation to the different muscles used and the respective motor donors. Seventy-three muscles were transferred for elbow flexion and ten for elbow extension. Latissimus dorsi (LD) was used in 37 cases, gracilis in 28, rectus femoris (RF) in seven, and vastus lateralis in one. Five LD and five gracilis were transferred for elbow extension. Patients younger than 15 years yielded better results than older patients for elbow flexion. When LD was transferred, the mean muscle grading (MG) was 3.33 +/- 0.25 when the neurotization was from intercostals; these outcomes were statistically significant when compared with outcomes of free gracilis transfer (MG 2.25 +/- 0.6). There was also a statistically significant difference when free LD was neurotized with three intercostals as compared with two intercostals nerves. RF yielded also good results when neurotized from contralateral C7 (cC7; MG 3.67 +/- 0.6). For elbow extension, the better outcomes of LD were not statistically significant. Among all the free muscle transfers for upper extremity reconstruction, elbow reanimation yielded the most rewarding outcomes. The selection of powerful muscle units was more important than the effect of neurotization which was not as strong as it was in muscle transfers for facial or hand reanimation

PURPOSE: The purpose of the present study was to assess the safety and efficacy of oral diclofenac potassium liquid-filled soft gelatin capsule (DPSGC) that uses ProSorb dispersion technology (Xanodyne Pharmaceuticals, Inc, licensed from AAIPharma, Wilmington, NC), to treat adult patients with acute pain after third molar extraction. PATIENTS AND METHODS: In the present multicenter, randomized, double-blind, placebo-controlled trial, patients experiencing a baseline level of pain (>/= 50 mm on a 100-mm visual analog scale within 4 hours after surgery) were randomized to receive a single dose of DPSGC at 25, 50, or 100 mg or placebo. Pain intensity and relief were assessed for 6 hours after dosing. The efficacy endpoints included the summed pain intensity difference, total pain relief, and the median time to the onset of perceptible and meaningful pain relief (using the 2-stopwatch method). RESULTS: A total of 249 randomized patients had a significant increase in the summed pain intensity difference and total pain relief values at 3 and 6 hours across all DPSGC-treated groups compared with the placebo group (P < .0001). The onset of perceptible and meaningful pain relief was significantly faster in all DPSGC groups than in the placebo group, including the DPSGC 25-mg group (25 minutes [P = .0002] and 52 minutes [P < .0001] for perceptible and meaningful pain relief, respectively). Significantly fewer patients in the DPSGC groups required rescue medication compared with those in the placebo group (P < .0001). The global evaluation scores were significantly greater for the patients who received DPSGC than for those who received placebo (P < .0001), and more than 65% of DPSGC-treated patients rated the medication as good, very good, or excellent compared with 18% of the placebo-treated patients. DPSGC was generally well tolerated, and no serious adverse events were reported. CONCLUSIONS: The results from the present single-dose study of postoperative dental pain suggest that DPSGC offers significant pain relief compared with placebo and that the study medication provided was well tolerated by patients who required pain relief after third molar extraction

ABSTRACT Purpose: Chipping within veneering porcelain has resulted in high clinical failure rates for implant-supported zirconia (yttria-tetragonal zirconia polycrystals [Y-TZP]) bridges. This study evaluated the reliability and failure modes of mouth-motion step-stress fatigued implant-supported Y-TZP versus palladium-silver alloy (PdAg) three-unit bridges. Materials and Methods: Implant-abutment replicas were embedded in polymethylmethacrylate resin. Y-TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact-tested to obtain ultimate failure load. In each framework group, 18 specimens were distributed across three step-stress profiles and mouth-motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. Results: PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y-TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (two-sided at 90% confidence intervals) for a 'mission' of 50,000 and 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft, Tucson, AZ, USA). No difference in reliability was observed between groups for a mission of 50,000. Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y-TZP. Conclusions: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300 N. Failure modes differed between materials

Summary form only given. This study aims to evaluate the potential of atmospheric pressure non-thermal plasma technology (NPT) to enhance the adhesive bond strength on normative dentin substrates. Two different microplasma jets were used in our experiments, a direct-current driven microhollow cathode discharge jet operated in air and a rf-driven jet operated in Ar. Other gas mixtures, e.g. He/O2 are also being explored.Initial experiments were carried out using fresh, non-carious third molars obtained under a protocol approved by the New York University College of Medicine Institutional Review Board. The occlusal enamel of each tooth was removed perpendicular to the long axis of the tooth to expose a flat dentin surface, which was subsequently polished. The specimens were randomly assigned to 3 groups for bonding and NPT applications. For the control group, three teeth were etched with phosphoric acid etched, the dentin bonding agent (DBA) was applied and the teeth were restored with a 4 mm thick resin composite. Another group of 3 teeth was treated with an Ar plasma and a third group was exposed to an air plasma. For the plasma-treated groups, the dentin substrates were etched for 15 s, rinsed for 10s and treated by the plasma for 20 s followed by DBA application and resin composite placement. All specimens were stored in water for 24 h prior to a microtensile bonding test. Preliminary data indicate that the bond strength values were not significantly affected by the Ar or air plasma treatment. We observed that teeth treated with the Ar plasma exhibited an enhanced premature failure rate (-50%) during the cutting or specimen mounting phases. This was not observed for the control or for the air plasma treated groups. Extensive surface characterization studies using various microscopy techniques, XPS, and micro-Raman are underway to assess the effect of the plasma on the surface. Optical emission spectroscopy is used to monitor the presence of reactive spe- - cies (eg. OH, O) in the plasma for various operating conditions and feed gases or gas mixtures. The results of these studies will be presented and discussed in detail at the Conference

In a crown system, core fracture requires replacement of the restoration. Understanding maximum principal stress concentration in the veneered core of a tooth-crown system as a function of variations in clinically relevant parameters is crucial in the rational design of crown systems. This study evaluated the main and interacting effects of a set of clinical variables on the maximum principal stress (MPS) in the core of an anatomically correct veneer-core-cement-tooth model. A 3D CAD model of a mandibular first molar crown was generated; tooth preparation was modeled by reducing the proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. A cemented veneered core crown was modeled on the preparation. This 'crown system' permitted finite element model investigation of the main and interacting effects of proximal wall height reduction, core material, core thickness, cement modulus, cement thickness, and load position on the maximum stress distribution in a factorial design. Analysis of variance was used to identify the main and interacting influences on the level of MPS in the crown core. Statistical significance was set at p<0.05. MPS levels varied as a function of two-way interactions between the following: core thickness and load position; cement thickness and load position; cement modulus and load position; cement thickness and core thickness; and cement thickness and cement modulus; and also three-way interactions among the load position, core material, and proximal wall height reduction, and among the core thickness, cement thickness, and cement modulus. MPS in the crown-tooth system is influenced by the design parameters and also by the interaction among them. Hence, while the geometry of molar crowns is complex, these analyses identify the factors that influence MPS and suggest levels that will minimize the core MPS in future studies of crown design

OBJECTIVES: To compare the reliability of the disto-facial (DF) and mesio-lingual (ML) cusps of an anatomically correct zirconia (Y-TZP) crown system. The research hypotheses tested were: (1) fatigue reliability and failure mode are similar for the ML and DF cusps; (2) failure mode of one cusp does not affect the failure of the other. METHODS: The average dimensions of a mandibular first molar crown were imported into CAD software; a tooth preparation was modelled by 1.5 mm marginal high reduction of proximal walls and occlusal surface by 2.0 mm. The CAD-based tooth preparation was milled and used as a die to fabricate crowns (n=14) with porcelain veneer on a 0.5 mm Y-TZP core. Crowns were cemented on composite reproductions of the tooth preparation. The crowns were step-stress mouth motion fatigued with sliding (0.7 mm) a tungsten-carbide indenter of 6.25 mm diameter down on the inclines of either the DF or ML cusps. Use level probability Weibull curve with use stress of 200 N and the reliability for completion of a mission of 50,000 cycles at 200 N load were calculated. RESULTS: Reliability for a 200 N at 50,000 cycles mission was not different between tested cusps. SEM imaging showed large cohesive failures within the veneer for the ML and smaller for the DF. Fractures originated from the contact area regardless of the cusp loaded. CONCLUSION: No significant difference on fatigue reliability was observed between the DF compared to the ML cusp. Fracture of one cusp did not affect the other

OBJECTIVES: This study compared the reliability and fracture patterns of zirconia cores veneered with pressable porcelain submitted to either axial or off-axis sliding contact fatigue. METHODS: Forty-two Y-TZP plates (12mm x 12mm x 0.5mm) veneered with pressable porcelain (12mm x 12mm x 1.2mm) and adhesively luted to water aged composite resin blocks (12mm x 12mm x 4mm) were stored in water at least 7 days prior to testing. Profiles for step-stress fatigue (ratio 3:2:1) were determined from single load to fracture tests (n=3). Fatigue loading was delivered on specimen either on axial (n=18) or off-axis 30 degrees angulation (n=18) to simulate posterior tooth cusp inclination creating a 0.7mm slide. Single load and fatigue tests utilized a 6.25mm diameter WC indenter. Specimens were inspected by means of polarized-light microscope and SEM. Use level probability Weibull curves were plotted with 2-sided 90% confidence bounds (CB) and reliability for missions of 50,000 cycles at 200N (90% CB) were calculated. RESULTS: The calculated Weibull Beta was 3.34 and 2.47 for axial and off-axis groups, respectively, indicating that fatigue accelerated failure in both loading modes. The reliability data for a mission of 50,000 cycles at 200N load with 90% CB indicates no difference between loading groups. Deep penetrating cone cracks reaching the core-veneer interface were observed in both groups. Partial cones due to the sliding component were observed along with the cone cracking for the off-axis group. No Y-TZP core fractures were observed. CONCLUSIONS: Reliability was not significantly different between axial and off-axis mouth-motion fatigued pressed over Y-TZP cores, but incorporation of sliding resulted in more aggressive damage on the veneer

OBJECTIVE: To evaluate the effects of clinically relevant variables on the maximum principal stress (MPS) in the veneer layer of an anatomically correct veneer-core-cement-tooth model. METHODS: The average dimensions of a mandibular first molar crown were imported into CAD software; a tooth preparation was modeled by reducing the proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. 'Crown systems' were composed by varying characteristics of a cement layer, structural core, and veneer solid, all designed to fit the tooth preparation. The main and interacting effects of proximal wall height reduction, core material, core thickness, cement modulus, cement thickness, and load position on the maximum stress distribution were derived from a series of finite element models and analyzed in a factorial analysis of variance. RESULTS: The average MPS in the veneer layer over the 64 models was 488 MPa (range = 248-840 MPa). MPS increased significantly with the addition of horizontal load components and with increasing cement thickness. In addition, MPS levels varied as a function of interactions between: proximal wall height reduction and load position; load position and cement thickness; core thickness and cement thickness; cement thickness and proximal wall height reduction; and core thickness, cement thickness and proximal wall height reduction. CONCLUSION: Rational design of veneered structural ceramics must consider the complex geometry of the crown-tooth system and integrate the influence of both the main effects and interactions among design parameters

This study evaluated the stress levels at the core layer and the veneer layer of zirconia crowns (comprising an alternative core design vs. a standard core design) under mechanical/thermal simulation, and subjected simulated models to laboratory mouth-motion fatigue. The dimensions of a mandibular first molar were imported into computer-aided design (CAD) software and a tooth preparation was modeled. A crown was designed using the space between the original tooth and the prepared tooth. The alternative core presented an additional lingual shoulder that lowered the veneer bulk of the cusps. Finite element analyses evaluated the residual maximum principal stresses fields at the core and veneer of both designs under loading and when cooled from 900 degrees C to 25 degrees C. Crowns were fabricated and mouth-motion fatigued, generating master Weibull curves and reliability data. Thermal modeling showed low residual stress fields throughout the bulk of the cusps for both groups. Mechanical simulation depicted a shift in stress levels to the core of the alternative design compared with the standard design. Significantly higher reliability was found for the alternative core. Regardless of the alternative configuration, thermal and mechanical computer simulations showed stress in the alternative core design comparable and higher to that of the standard configuration, respectively. Such a mechanical scenario probably led to the higher reliability of the alternative design under fatigue