Mark Beatty | University of Nebraska Medical Center (original) (raw)

Papers by Mark Beatty

The Journal of prosthetic dentistry, Jan 16, 2016

Whether using tap water to rinse off debris will make a clinical difference to the surface detail... more Whether using tap water to rinse off debris will make a clinical difference to the surface detail of a gypsum cast is unknown. In addition, how best to remove debris from the cast is unknown. The purpose of this in vitro study was to evaluate the efficiency of different methods of cleaning a gypsum cast after trimming and the effect of short-term exposure to tap water on the surface quality of the cast. A die fitting American National Standards Institute/American Dental Association specification 25 (International Standards Organization specification 6873) for dental gypsum products was embedded in a Dentoform with the machined lines positioned at the same level as the occlusal surface of the posterior teeth. A flat plate was used to ensure that the plane of occlusion for the die was at the same position as the posterior teeth. Forty polyvinyl siloxane impressions of the Dentoform were made and poured with vacuum-mixed improved Type IV dental stone. Each cast was inspected for the ac...

Journal of Orofacial Pain, 2003

To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc un... more To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc under repeated physiologic loading before and after an impact event. Two groups, each consisting of 10 discs, were subjected to repeated tensile cycling in the dorsoventral (group 1) and mediolateral (group 3) direction. Two additional groups, each consisting of 10 discs, had preconditioning in the form of a 1.18 N.s impulsive load before tensile cycling in either the dorsoventral (group 2) or mediolateral (group 4) direction. Physiologic loads of 1 to 3 N were cycled at 0.1 Hz, and stress-strain responses were recorded every cycle between 1 to 10 cycles, and then periodically at 50, 100, 500, 750, and 1,000 cycles. The properties of elastic modulus, residual strain upon unloading, and area contained within the hysteresis loop were measured. Dorsoventral loading produced 5-fold higher elastic modulus, 5-fold lower residual strain, and 5-fold lower hysteresis compared to mediolateral tensile loading (P < or = .001). Repeated loading effectively reduced the viscous response for all discs, as the elastic modulus increased while residual strain and hysteresis decreased. Impulsive loading caused elastic modulus to increase for dorsoventrally cycled discs, whereas hysteresis decreased for mediolaterally cycled discs (P < or = .05). The findings suggest that damage from the impact load may have increased the porosity of the extracellular matrix, which ultimately resulted in additional stress transfer to the collagen fibers during loading. Impulsive loads may be an important preconditioning factor in the fatigue failure of the TMJ disc in vivo.

Journal of Periodontology, Sep 30, 2014

This study evaluates the performance of self-report against the reference standard of clinically ... more This study evaluates the performance of self-report against the reference standard of clinically defined periodontitis in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) after accounting for factors associated with periodontitis. Six self-report periodontitis questions were evaluated in patients with RA and OA. Questions were validated against a reference standard of severe and moderate-to-severe periodontitis based on full-mouth examination. Multivariable logistic regression was used to evaluate the performance of: 1) self-report alone; 2) age, sex, education, and smoking status; and 3) a combination of the above. Model performance was assessed using the c-statistic. Convergent validity of self-reported "bone loss/deep pockets" and "loose teeth" was assessed; associations of self-report with RA disease characteristics were explored. Self-report performed similarly in RA and OA, with individual question specificity for periodontitis ≥68% and sensitivity from 9.8% to 45%. Question-only models yielded c-statistics of 0.66 to 0.72, whereas risk factor-only models yielded c-statistics of 0.74 to 0.79. The highest-performing models incorporated both self-report questions and periodontitis risk factors, with c-statistics ≥0.79. Greater radiographic alveolar bone loss was observed among participants reporting "bone loss/deep pockets" (P <0.001) and "loose teeth" (P…

Journal of prosthodontics : official journal of the American College of Prosthodontists, Jan 23, 2015

Controversy exists as to whether lining a metal-perforated impression tray with wax will yield a ... more Controversy exists as to whether lining a metal-perforated impression tray with wax will yield a distorted irreversible hydrocolloid impression. Two current textbooks have completely different recommendations, but there is no evidence to support either theory. This project evaluates distortion in gypsum casts that have been prepared from wax-lined and unlined metal impression trays. The purpose of this study was to assess the influence of wax on the border and in the palate of metal-perforated impression trays on the dimensional stability of the resulting irreversible hydrocolloid impression. A dentaform was prepared with marks on the cusp tips of teeth 6 and 11 and distobuccal cusps of teeth 2 and 15. Using a standard maxillary rim lock impression tray, alginate impressions were made using a dentaform with no wax lining, wax lining the border of the tray, and wax lining the border and the palate (n = 10). Casts were randomized. Six measurements were taken using a stereographic meas...

General dentistry

Trace-element neurotoxicity contributing to the development of Alzheimer's disease (AD) m... more Trace-element neurotoxicity contributing to the development of Alzheimer's disease (AD) may be an important etiologic factor for this disorder. This clinical study was conducted to determine the urine concentrations of mercury (Hg) from patients with AD disorders. Within the confines of a nursing home, all subjects were exposed to the same environment and a diet that excluded seafood. The results of this study do not indicate that subjects with AD have a greater body burden of Hg, according to urinary excretion. This can be further evidence that Hg from amalgam restorations or diet is not related to etiology and pathogenesis of AD.

Objective: Little is known about nanoparticle size and elastomer reinforcement. This study's ... more Objective: Little is known about nanoparticle size and elastomer reinforcement. This study's purpose was to assess tensile mechanical and Durometer properties of PDMS loaded with 2-3 nm (S), 20-30 nm (M) and 200-300 nm (L) ZrO2. Methods: 1 wt% nanoparticles and 0.2% functional intrinsic yellow pigment were mixed into vinyl-terminated PDMS, then polymerized into dumbbells (ASTM D412, n=12) and discs 34 mm diameter x 6 mm thick (n=5). Samples were weathered for 3000 h in UVB (UV) (0.72 J/cm2/h), heat (H) (65C), humidity (Hu) (80%r.h.) or control (C) (darkness, 25C, 30%r.h.). Strength (UTS), Strain at break (ε), Modulus (E) and Durometer disc hardness (D) were measured at baseline (B) and after weathering. Property differences were compared according to nanoparticle size and test condition (ANOVA/Tukey). Results: UTS: S<M=L (p<0.05), not affected by test condition (p≥0.05). ε: S=L<M, UV<H=Hu=C=B (p<0.05). D: S<M=L (p<0.05) at baseline, overall changes caused by...

Cyclic tensile tests of thin PDMS dumbbells are capable of detecting early mechanical changes cau... more Cyclic tensile tests of thin PDMS dumbbells are capable of detecting early mechanical changes caused by UVB exposure (#3186,IADR 2008). Objective: This study assessed the same fatigue protocol for identifying early physical changes within PDMS following short-term exposures to heat and humidity. Methods: PDMS dumbbells (ASTM D412,n=6) were constructed with 13 wt% silica, no pigment, thickness either 2 mm or 0.3 mm and placed into one of four groups: (I) immediate mechanical testing, (C) 600h control (25C,30%r.h.), (Ht) 600h heat exposure (65C,30%r.h.), (Hu) 600h high humidity (25C,80%r.h.). A modified Stepwise Increasing Strain Test (El Fray et al., Polymer, 2004) was followed to produce 4 stress-strain (s-s) curves for each dumbbell: (1) baseline, (2) after 1000 cycles 25% tensile strain, (3) additional 1000 cycles 50% strain, (4) additional 1000 cycles 100% strain. Triangular waveforms and 1 Hz cycling were followed. Measured parameters: Elastic modulus at 80-100% strain, area wit...

Objective: Previously yellow glass-based pigments demonstrated improved color stability in weathe... more Objective: Previously yellow glass-based pigments demonstrated improved color stability in weathered elastomers (AADR 2010 #724). This study assessed tensile properties of elastomers colored with intrinsic, extrinsic and glass pigments. Methods: 10 wt% red, yellow, violet or tan pigments were mixed into vinyl-terminated PDMS containing 13 wt% silica filler. Each mixture was combined with equimolar polymethyl hydrogen siloxane crosslinker and materials were polymerized into dumbbells (ASTM D412, n=20). 3000 h weathering challenges included UVB (0.72 J/cm2/h), heat (65C), humidity (80% r.h.) and control (darkness, 25C, 30% r.h.). Uniaxial tensile tests at 500 mm/min with extensometer measured strength (UTS), breaking strain (BS) and Young's modulus between 50-100% strain (M). Tensile property differences were compared according to color, pigment type and weathering exposure (ANOVA/Tukey, p≤0.01). Results: UVB- UTS(MPa): Color- red(1.12)a yellow(1.08)a violet(0.96)b tan(0.86)b. Typ...

Objective: Facial prostheses fade and harden with repeated weathering challenges. This study'... more Objective: Facial prostheses fade and harden with repeated weathering challenges. This study's purpose was to assess the UV-blocking potential of nano-sized TiO2 when added to facial elastomers. Methods: 0, 100, 500 ppm rutile TiO2 (30-40 nm diameter) were ultrasonically dispersed into vinyl-terminated PDMS. Silica filler (13 wt%) and functional intrinsic yellow pigment (0.5 wt%) were added and the mixture combined with equimolar polymethyl hydrogen siloxane crosslinker. Materials were polymerized into dumbbells (ASTM D412,n=6) and weathered in either UVB (0.72 J/cm2/h) or darkness (control) for 600h,1800h,3000h. CIEL*a*b* color was measured at each time interval and tensile properties measured separately for groups constructed immediately and those weathered for 3000h. Color and tensile property differences were compared according to TiO2 additions and weathering exposure (ANOVA/Tukey). Results: 3000h data are presented in the table below. Mean(s.e.m.) values are shown; all sup...

Objective: Facial prosthetic elastomers with wide ranges in hardness are now available, yet mater... more Objective: Facial prosthetic elastomers with wide ranges in hardness are now available, yet material weatherability is unknown. This study assessed color, durometer and tensile property changes after 3000 hours of outdoor weathering in Lincoln, NE, USA. Methods: Unpigmented elastomers with durometer values 5, 30, 50, 70 and controls (A2186) were polymerized into dumbbells (ASTM D412) and discs 34 mm diameter x 6 mm thick (all Factor II materials). Materials were subjected to outdoor or control (25C, 30% r.h., darkness) environments for 3000 hours. CIEL*a*b* color (n=5), durometer hardness (n=5) and tensile properties (n=10) were measured at 0 & 3000 hours, and group differences were assessed by material and weathering condition (ANOVA/Tukey). Results: Mean durometer changes for all materials were ≤3.0, with no significant differences observed between control and weathered groups for any material (p>0.05). 3000 hour color and tensile property results are presented below (mean (s.e...

Objective: Colorants in facial prostheses fade after repeated weathering exposures. This study&#3... more Objective: Colorants in facial prostheses fade after repeated weathering exposures. This study's purpose was to assess color stability of experimental glasses and commercial pigments following exposures to isolated components of weathering. Methods: Red (RG) and yellow (YG) glass powders (Kugler) were sieved to produce particle diameters <38 um. To achieve color saturation, powders were mixed 10% by weight into silica-filled, vinyl-terminated PDMS. Commercially pigmented mixtures containing functional intrinsic red (IR), extrinsic red (ER), intrinsic yellow (IY), extrinsic yellow (EY) were prepared (Factor II), plus an unpigmented mixture (U). Materials were polymerized into dumbbells (ASTM D412,n=10) and were weathered for 3000 h in UVB (0.72 J/cm2/h), heat (65C), humidity (80%r.h.), outdoors or control (darkness, 25C, 30%r.h.). Changes in L*a*b*E* color were measured and compared according to pigment and test condition (ANOVA/Tukey). Results: Greater color parameter changes...

Objectives: This study assessed color and durometer hardness changes resulting from controlled UV... more Objectives: This study assessed color and durometer hardness changes resulting from controlled UVB exposures delivered to pigmented PDMS elastomers. Cosmetic red (CR) and yellow (CY), nanoclay red (NR) and orange (NO), functional intrinsic red (IR) and yellow ochre (IYO), extrinsic red (ER) and yellow ochre (EYO) pigments, plus unpigmented controls (U) were compared. Methods: 0.1 wt% pigment was mixed into vinyl-terminated PDMS containing 13 wt% silica filler. Equimolar polymethyl hydrogen siloxane crosslinker was added and the mixture polymerized into discs 34 mm diameter x 6 mm thick. Each formulation was subjected to UVB radiation (0.72 J/cm2/h,25C,30% r.h.) or control environment (darkness,25C,30% r.h.). CIEL*a*b* color and durometer hardness were measured at 0, 600, 1800 hours (n=5), and group differences assessed by pigment and environment (ANOVA/Tukey, p≤0.01). Results: After 600 hours, color changes were imperceptible (ΔE*<1.1), except for UVB-exposed NO (ΔE*=6.8) and NR ...

Seminars in Orthodontics, 2003

The efficiency of tooth movement associated with orthodontic sliding mechanics can be compromised... more The efficiency of tooth movement associated with orthodontic sliding mechanics can be compromised by friction between arch wire and tube or bracket slot. The described studies measured the apparent coefficient of static friction ( a ) during sliding along an arch wire. Known moments were applied to simulate tooth tipping. Measurements tested whether intraoral vibration during gum chewing reduced friction. The first experiments measured intraoral friction associated with the sliding of 4 and 8 mm stainless steel (SS) tubes along a SS auxiliary arch wire, in 10 subjects. Mean intraoral a for 4 and 8 mm tubes were 0.12 (SD ‫؍‬ 0.04) and 0.17 (SD ‫؍‬ 0.05), respectively. Analysis of variance (ANOVA) showed that a was significantly higher (P < 0.001) for the longer tubes. Although intraoral vibration decreased a compared with bench-top tests (P < 0.001), frictional resistance was never completely eliminated.

The Journal of prosthetic dentistry, 2015

Facial prosthetic elastomers with wide ranges in hardness are available, yet material weatherabil... more Facial prosthetic elastomers with wide ranges in hardness are available, yet material weatherability is unknown. The purpose of this study was to assess color, Durometer hardness, and tensile property changes after 3000 hours of outdoor weathering. Unpigmented elastomers with Durometer hardness 5, 30, 50, 70, and A-2186 were polymerized into dumbbells (ASTM D412) and disks, 34 mm in diameter by 6 mm thick. Materials were subjected to outdoor or time passage environments for 3000 hours. CIELab color (n=5), Durometer hardness (n=5), and tensile mechanical properties (n=10) were measured at 0 and 3000 hours, and group differences were assessed by material and weathering condition (ANOVA/Tukey, α=.05). Except for A-2186, the mean Durometer changes for all materials were 1 unit or less, with no significant differences observed between time passage and weathered groups (P≥.05). Three-thousand-hour tensile mechanical property results demonstrated nonsignificant differences between time pas...

Journal of orofacial pain, 2003

To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc un... more To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc under repeated physiologic loading before and after an impact event. Two groups, each consisting of 10 discs, were subjected to repeated tensile cycling in the dorsoventral (group 1) and mediolateral (group 3) direction. Two additional groups, each consisting of 10 discs, had preconditioning in the form of a 1.18 N.s impulsive load before tensile cycling in either the dorsoventral (group 2) or mediolateral (group 4) direction. Physiologic loads of 1 to 3 N were cycled at 0.1 Hz, and stress-strain responses were recorded every cycle between 1 to 10 cycles, and then periodically at 50, 100, 500, 750, and 1,000 cycles. The properties of elastic modulus, residual strain upon unloading, and area contained within the hysteresis loop were measured. Dorsoventral loading produced 5-fold higher elastic modulus, 5-fold lower residual strain, and 5-fold lower hysteresis compared to mediolateral tensil...

Journal of periodontology, 2015

This study evaluates the performance of self-report against the reference standard of clinically ... more This study evaluates the performance of self-report against the reference standard of clinically defined periodontitis in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) after accounting for factors associated with periodontitis. Six self-report periodontitis questions were evaluated in patients with RA and OA. Questions were validated against a reference standard of severe and moderate-to-severe periodontitis based on full-mouth examination. Multivariable logistic regression was used to evaluate the performance of: 1) self-report alone; 2) age, sex, education, and smoking status; and 3) a combination of the above. Model performance was assessed using the c-statistic. Convergent validity of self-reported "bone loss/deep pockets" and "loose teeth" was assessed; associations of self-report with RA disease characteristics were explored. Self-report performed similarly in RA and OA, with individual question specificity for periodontitis ≥68% and sensi...

Tissue engineering is a new methodology for addressing meniscal injury or loss. Synovium may be a... more Tissue engineering is a new methodology for addressing meniscal injury or loss. Synovium may be an ideal source of cells for in vitro meniscal fibrocartilage formation, however, favorable in vitro culture conditions for synovium must be established in order to achieve this goal. The objective of this study was to determine cellularity, cell distribution, and extracellular matrix (ECM) formation of equine fibroblast-like synoviocytes (FLS) cultured on synthetic scaffolds, for potential application in synovium-based meniscal tissue engineering. Scaffolds included open-cell poly-L-lactic acid (OPLA) sponges and polyglycolic acid (PGA) scaffolds cultured in static and dynamic culture conditions, and PGA scaffolds coated in poly-L-lactic (PLLA) in dynamic culture conditions. Materials and Methods. Equine FLS were seeded on OPLA and PGA scaffolds, and cultured in a static environment or in a rotating bioreactor for 12 days. Equine FLS were also seeded on PGA scaffolds coated in 2% or 4% PLLA and cultured in a rotating bioreactor for 14 and 21 days. Three scaffolds from each group were fixed, sectioned and stained with Masson's Trichrome, Safranin-O, and Hematoxylin and Eosin, and cell numbers and distribution were analyzed using computer image analysis. Three PGA and OPLA scaffolds from each culture condition were also analyzed for extracellular matrix (ECM) production via dimethylmethylene blue (sulfated glycosaminoglycan) assay and hydroxyproline (collagen) assay. PLLA coated PGA scaffolds were analyzed using double stranded DNA quantification as areflection of cellularity and confocal laser microscopy in a fluorescent cell viability assay. Results. The highest cellularity occurred in PGA constructs cultured in a rotating bioreactor, which also had a mean sulfated glycosaminoglycan content of 22.3 µg per scaffold. PGA constructs cultured in static conditions had the lowest cellularity. Cells had difficulty adhering to OPLA and the PLLA coating of PGA scaffolds; cellularity was inversely proportional to the concentration of PLLA used. PLLA coating did not prevent dissolution of the PGA scaffolds. All cell scaffold types and culture conditions produced non-uniform cellular distribution. How to cite this article Warnock et al. (2014), Culture of equine fibroblast-like synoviocytes on synthetic tissue scaffolds towards meniscal tissue engineering: a preliminary cell-seeding study. PeerJ 2:e353; DOI 10.7717/peerj.353

Journal of Tropical Medicine, 2014

A dengue fever surveillance study was conducted at three medical facilities located in the low-in... more A dengue fever surveillance study was conducted at three medical facilities located in the low-income district of San Javier in Medellin, Colombia. During March 2008 to 2009, 781 patients with fever regardless of chief complaint were recruited for acute dengue virus infection testing. Of the 781 tested, 73 (9.3%) were positive for dengue infection. Serotypes DENV-2 (77%) and -3 (23%) were detected by PCR. One patient met the diagnostic criteria for dengue hemorrhagic fever. Only 3 out of 73 (4.1%) febrile subjects testing positive for dengue infection were diagnosed with dengue fever by the treating physician. This study confirms dengue virus as an important cause of acute febrile illness in Medellin, Colombia, but it is difficult to diagnose without dengue diagnostic testing.

Arthritis & rheumatology (Hoboken, N.J.), 2014

To examine the degree to which shared risk factors explain the relationship of periodontitis (PD)... more To examine the degree to which shared risk factors explain the relationship of periodontitis (PD) to rheumatoid arthritis (RA) and to determine the associations of PD and Porphyromonas gingivalis with pathologic and clinical features of RA. Patients with RA (n = 287) and patients with osteoarthritis as disease controls (n = 330) underwent a standardized periodontal examination. The HLA-DRB1 status of all participants was imputed using single-nucleotide polymorphisms from the extended major histocompatibility complex. Circulating anti-P gingivalis antibodies were measured using an enzyme-linked immunosorbent assay, and subgingival plaque was assessed for the presence of P gingivalis using polymerase chain reaction (PCR). Associations of PD with RA were examined using multivariable regression. Presence of PD was more common in patients with RA and patients with anti-citrullinated protein antibody (ACPA)-positive RA (n = 240; determined using the anti-cyclic citrullinated peptide 2 [an...

The Journal of prosthetic dentistry, Jan 16, 2016

Whether using tap water to rinse off debris will make a clinical difference to the surface detail... more Whether using tap water to rinse off debris will make a clinical difference to the surface detail of a gypsum cast is unknown. In addition, how best to remove debris from the cast is unknown. The purpose of this in vitro study was to evaluate the efficiency of different methods of cleaning a gypsum cast after trimming and the effect of short-term exposure to tap water on the surface quality of the cast. A die fitting American National Standards Institute/American Dental Association specification 25 (International Standards Organization specification 6873) for dental gypsum products was embedded in a Dentoform with the machined lines positioned at the same level as the occlusal surface of the posterior teeth. A flat plate was used to ensure that the plane of occlusion for the die was at the same position as the posterior teeth. Forty polyvinyl siloxane impressions of the Dentoform were made and poured with vacuum-mixed improved Type IV dental stone. Each cast was inspected for the ac...

Journal of Orofacial Pain, 2003

To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc un... more To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc under repeated physiologic loading before and after an impact event. Two groups, each consisting of 10 discs, were subjected to repeated tensile cycling in the dorsoventral (group 1) and mediolateral (group 3) direction. Two additional groups, each consisting of 10 discs, had preconditioning in the form of a 1.18 N.s impulsive load before tensile cycling in either the dorsoventral (group 2) or mediolateral (group 4) direction. Physiologic loads of 1 to 3 N were cycled at 0.1 Hz, and stress-strain responses were recorded every cycle between 1 to 10 cycles, and then periodically at 50, 100, 500, 750, and 1,000 cycles. The properties of elastic modulus, residual strain upon unloading, and area contained within the hysteresis loop were measured. Dorsoventral loading produced 5-fold higher elastic modulus, 5-fold lower residual strain, and 5-fold lower hysteresis compared to mediolateral tensile loading (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = .001). Repeated loading effectively reduced the viscous response for all discs, as the elastic modulus increased while residual strain and hysteresis decreased. Impulsive loading caused elastic modulus to increase for dorsoventrally cycled discs, whereas hysteresis decreased for mediolaterally cycled discs (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or = .05). The findings suggest that damage from the impact load may have increased the porosity of the extracellular matrix, which ultimately resulted in additional stress transfer to the collagen fibers during loading. Impulsive loads may be an important preconditioning factor in the fatigue failure of the TMJ disc in vivo.

Journal of Periodontology, Sep 30, 2014

This study evaluates the performance of self-report against the reference standard of clinically ... more This study evaluates the performance of self-report against the reference standard of clinically defined periodontitis in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) after accounting for factors associated with periodontitis. Six self-report periodontitis questions were evaluated in patients with RA and OA. Questions were validated against a reference standard of severe and moderate-to-severe periodontitis based on full-mouth examination. Multivariable logistic regression was used to evaluate the performance of: 1) self-report alone; 2) age, sex, education, and smoking status; and 3) a combination of the above. Model performance was assessed using the c-statistic. Convergent validity of self-reported &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;bone loss/deep pockets&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;loose teeth&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; was assessed; associations of self-report with RA disease characteristics were explored. Self-report performed similarly in RA and OA, with individual question specificity for periodontitis ≥68% and sensitivity from 9.8% to 45%. Question-only models yielded c-statistics of 0.66 to 0.72, whereas risk factor-only models yielded c-statistics of 0.74 to 0.79. The highest-performing models incorporated both self-report questions and periodontitis risk factors, with c-statistics ≥0.79. Greater radiographic alveolar bone loss was observed among participants reporting &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;bone loss/deep pockets&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001) and &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;loose teeth&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; (P…

Journal of prosthodontics : official journal of the American College of Prosthodontists, Jan 23, 2015

Controversy exists as to whether lining a metal-perforated impression tray with wax will yield a ... more Controversy exists as to whether lining a metal-perforated impression tray with wax will yield a distorted irreversible hydrocolloid impression. Two current textbooks have completely different recommendations, but there is no evidence to support either theory. This project evaluates distortion in gypsum casts that have been prepared from wax-lined and unlined metal impression trays. The purpose of this study was to assess the influence of wax on the border and in the palate of metal-perforated impression trays on the dimensional stability of the resulting irreversible hydrocolloid impression. A dentaform was prepared with marks on the cusp tips of teeth 6 and 11 and distobuccal cusps of teeth 2 and 15. Using a standard maxillary rim lock impression tray, alginate impressions were made using a dentaform with no wax lining, wax lining the border of the tray, and wax lining the border and the palate (n = 10). Casts were randomized. Six measurements were taken using a stereographic meas...

General dentistry

Trace-element neurotoxicity contributing to the development of Alzheimer&#39;s disease (AD) m... more Trace-element neurotoxicity contributing to the development of Alzheimer&#39;s disease (AD) may be an important etiologic factor for this disorder. This clinical study was conducted to determine the urine concentrations of mercury (Hg) from patients with AD disorders. Within the confines of a nursing home, all subjects were exposed to the same environment and a diet that excluded seafood. The results of this study do not indicate that subjects with AD have a greater body burden of Hg, according to urinary excretion. This can be further evidence that Hg from amalgam restorations or diet is not related to etiology and pathogenesis of AD.

Objective: Little is known about nanoparticle size and elastomer reinforcement. This study's ... more Objective: Little is known about nanoparticle size and elastomer reinforcement. This study's purpose was to assess tensile mechanical and Durometer properties of PDMS loaded with 2-3 nm (S), 20-30 nm (M) and 200-300 nm (L) ZrO2. Methods: 1 wt% nanoparticles and 0.2% functional intrinsic yellow pigment were mixed into vinyl-terminated PDMS, then polymerized into dumbbells (ASTM D412, n=12) and discs 34 mm diameter x 6 mm thick (n=5). Samples were weathered for 3000 h in UVB (UV) (0.72 J/cm2/h), heat (H) (65C), humidity (Hu) (80%r.h.) or control (C) (darkness, 25C, 30%r.h.). Strength (UTS), Strain at break (ε), Modulus (E) and Durometer disc hardness (D) were measured at baseline (B) and after weathering. Property differences were compared according to nanoparticle size and test condition (ANOVA/Tukey). Results: UTS: S<M=L (p<0.05), not affected by test condition (p≥0.05). ε: S=L<M, UV<H=Hu=C=B (p<0.05). D: S<M=L (p<0.05) at baseline, overall changes caused by...

Cyclic tensile tests of thin PDMS dumbbells are capable of detecting early mechanical changes cau... more Cyclic tensile tests of thin PDMS dumbbells are capable of detecting early mechanical changes caused by UVB exposure (#3186,IADR 2008). Objective: This study assessed the same fatigue protocol for identifying early physical changes within PDMS following short-term exposures to heat and humidity. Methods: PDMS dumbbells (ASTM D412,n=6) were constructed with 13 wt% silica, no pigment, thickness either 2 mm or 0.3 mm and placed into one of four groups: (I) immediate mechanical testing, (C) 600h control (25C,30%r.h.), (Ht) 600h heat exposure (65C,30%r.h.), (Hu) 600h high humidity (25C,80%r.h.). A modified Stepwise Increasing Strain Test (El Fray et al., Polymer, 2004) was followed to produce 4 stress-strain (s-s) curves for each dumbbell: (1) baseline, (2) after 1000 cycles 25% tensile strain, (3) additional 1000 cycles 50% strain, (4) additional 1000 cycles 100% strain. Triangular waveforms and 1 Hz cycling were followed. Measured parameters: Elastic modulus at 80-100% strain, area wit...

Objective: Previously yellow glass-based pigments demonstrated improved color stability in weathe... more Objective: Previously yellow glass-based pigments demonstrated improved color stability in weathered elastomers (AADR 2010 #724). This study assessed tensile properties of elastomers colored with intrinsic, extrinsic and glass pigments. Methods: 10 wt% red, yellow, violet or tan pigments were mixed into vinyl-terminated PDMS containing 13 wt% silica filler. Each mixture was combined with equimolar polymethyl hydrogen siloxane crosslinker and materials were polymerized into dumbbells (ASTM D412, n=20). 3000 h weathering challenges included UVB (0.72 J/cm2/h), heat (65C), humidity (80% r.h.) and control (darkness, 25C, 30% r.h.). Uniaxial tensile tests at 500 mm/min with extensometer measured strength (UTS), breaking strain (BS) and Young's modulus between 50-100% strain (M). Tensile property differences were compared according to color, pigment type and weathering exposure (ANOVA/Tukey, p≤0.01). Results: UVB- UTS(MPa): Color- red(1.12)a yellow(1.08)a violet(0.96)b tan(0.86)b. Typ...

Objective: Facial prostheses fade and harden with repeated weathering challenges. This study'... more Objective: Facial prostheses fade and harden with repeated weathering challenges. This study's purpose was to assess the UV-blocking potential of nano-sized TiO2 when added to facial elastomers. Methods: 0, 100, 500 ppm rutile TiO2 (30-40 nm diameter) were ultrasonically dispersed into vinyl-terminated PDMS. Silica filler (13 wt%) and functional intrinsic yellow pigment (0.5 wt%) were added and the mixture combined with equimolar polymethyl hydrogen siloxane crosslinker. Materials were polymerized into dumbbells (ASTM D412,n=6) and weathered in either UVB (0.72 J/cm2/h) or darkness (control) for 600h,1800h,3000h. CIEL*a*b* color was measured at each time interval and tensile properties measured separately for groups constructed immediately and those weathered for 3000h. Color and tensile property differences were compared according to TiO2 additions and weathering exposure (ANOVA/Tukey). Results: 3000h data are presented in the table below. Mean(s.e.m.) values are shown; all sup...

Objective: Facial prosthetic elastomers with wide ranges in hardness are now available, yet mater... more Objective: Facial prosthetic elastomers with wide ranges in hardness are now available, yet material weatherability is unknown. This study assessed color, durometer and tensile property changes after 3000 hours of outdoor weathering in Lincoln, NE, USA. Methods: Unpigmented elastomers with durometer values 5, 30, 50, 70 and controls (A2186) were polymerized into dumbbells (ASTM D412) and discs 34 mm diameter x 6 mm thick (all Factor II materials). Materials were subjected to outdoor or control (25C, 30% r.h., darkness) environments for 3000 hours. CIEL*a*b* color (n=5), durometer hardness (n=5) and tensile properties (n=10) were measured at 0 & 3000 hours, and group differences were assessed by material and weathering condition (ANOVA/Tukey). Results: Mean durometer changes for all materials were ≤3.0, with no significant differences observed between control and weathered groups for any material (p>0.05). 3000 hour color and tensile property results are presented below (mean (s.e...

Objective: Colorants in facial prostheses fade after repeated weathering exposures. This study&#3... more Objective: Colorants in facial prostheses fade after repeated weathering exposures. This study's purpose was to assess color stability of experimental glasses and commercial pigments following exposures to isolated components of weathering. Methods: Red (RG) and yellow (YG) glass powders (Kugler) were sieved to produce particle diameters <38 um. To achieve color saturation, powders were mixed 10% by weight into silica-filled, vinyl-terminated PDMS. Commercially pigmented mixtures containing functional intrinsic red (IR), extrinsic red (ER), intrinsic yellow (IY), extrinsic yellow (EY) were prepared (Factor II), plus an unpigmented mixture (U). Materials were polymerized into dumbbells (ASTM D412,n=10) and were weathered for 3000 h in UVB (0.72 J/cm2/h), heat (65C), humidity (80%r.h.), outdoors or control (darkness, 25C, 30%r.h.). Changes in L*a*b*E* color were measured and compared according to pigment and test condition (ANOVA/Tukey). Results: Greater color parameter changes...

Objectives: This study assessed color and durometer hardness changes resulting from controlled UV... more Objectives: This study assessed color and durometer hardness changes resulting from controlled UVB exposures delivered to pigmented PDMS elastomers. Cosmetic red (CR) and yellow (CY), nanoclay red (NR) and orange (NO), functional intrinsic red (IR) and yellow ochre (IYO), extrinsic red (ER) and yellow ochre (EYO) pigments, plus unpigmented controls (U) were compared. Methods: 0.1 wt% pigment was mixed into vinyl-terminated PDMS containing 13 wt% silica filler. Equimolar polymethyl hydrogen siloxane crosslinker was added and the mixture polymerized into discs 34 mm diameter x 6 mm thick. Each formulation was subjected to UVB radiation (0.72 J/cm2/h,25C,30% r.h.) or control environment (darkness,25C,30% r.h.). CIEL*a*b* color and durometer hardness were measured at 0, 600, 1800 hours (n=5), and group differences assessed by pigment and environment (ANOVA/Tukey, p≤0.01). Results: After 600 hours, color changes were imperceptible (ΔE*<1.1), except for UVB-exposed NO (ΔE*=6.8) and NR ...

Seminars in Orthodontics, 2003

The efficiency of tooth movement associated with orthodontic sliding mechanics can be compromised... more The efficiency of tooth movement associated with orthodontic sliding mechanics can be compromised by friction between arch wire and tube or bracket slot. The described studies measured the apparent coefficient of static friction ( a ) during sliding along an arch wire. Known moments were applied to simulate tooth tipping. Measurements tested whether intraoral vibration during gum chewing reduced friction. The first experiments measured intraoral friction associated with the sliding of 4 and 8 mm stainless steel (SS) tubes along a SS auxiliary arch wire, in 10 subjects. Mean intraoral a for 4 and 8 mm tubes were 0.12 (SD ‫؍‬ 0.04) and 0.17 (SD ‫؍‬ 0.05), respectively. Analysis of variance (ANOVA) showed that a was significantly higher (P < 0.001) for the longer tubes. Although intraoral vibration decreased a compared with bench-top tests (P < 0.001), frictional resistance was never completely eliminated.

The Journal of prosthetic dentistry, 2015

Facial prosthetic elastomers with wide ranges in hardness are available, yet material weatherabil... more Facial prosthetic elastomers with wide ranges in hardness are available, yet material weatherability is unknown. The purpose of this study was to assess color, Durometer hardness, and tensile property changes after 3000 hours of outdoor weathering. Unpigmented elastomers with Durometer hardness 5, 30, 50, 70, and A-2186 were polymerized into dumbbells (ASTM D412) and disks, 34 mm in diameter by 6 mm thick. Materials were subjected to outdoor or time passage environments for 3000 hours. CIELab color (n=5), Durometer hardness (n=5), and tensile mechanical properties (n=10) were measured at 0 and 3000 hours, and group differences were assessed by material and weathering condition (ANOVA/Tukey, α=.05). Except for A-2186, the mean Durometer changes for all materials were 1 unit or less, with no significant differences observed between time passage and weathered groups (P≥.05). Three-thousand-hour tensile mechanical property results demonstrated nonsignificant differences between time pas...

Journal of orofacial pain, 2003

To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc un... more To test for orthotropy in the stress-strain behavior of the temporomandibular joint (TMJ) disc under repeated physiologic loading before and after an impact event. Two groups, each consisting of 10 discs, were subjected to repeated tensile cycling in the dorsoventral (group 1) and mediolateral (group 3) direction. Two additional groups, each consisting of 10 discs, had preconditioning in the form of a 1.18 N.s impulsive load before tensile cycling in either the dorsoventral (group 2) or mediolateral (group 4) direction. Physiologic loads of 1 to 3 N were cycled at 0.1 Hz, and stress-strain responses were recorded every cycle between 1 to 10 cycles, and then periodically at 50, 100, 500, 750, and 1,000 cycles. The properties of elastic modulus, residual strain upon unloading, and area contained within the hysteresis loop were measured. Dorsoventral loading produced 5-fold higher elastic modulus, 5-fold lower residual strain, and 5-fold lower hysteresis compared to mediolateral tensil...

Journal of periodontology, 2015

This study evaluates the performance of self-report against the reference standard of clinically ... more This study evaluates the performance of self-report against the reference standard of clinically defined periodontitis in patients with rheumatoid arthritis (RA) and osteoarthritis (OA) after accounting for factors associated with periodontitis. Six self-report periodontitis questions were evaluated in patients with RA and OA. Questions were validated against a reference standard of severe and moderate-to-severe periodontitis based on full-mouth examination. Multivariable logistic regression was used to evaluate the performance of: 1) self-report alone; 2) age, sex, education, and smoking status; and 3) a combination of the above. Model performance was assessed using the c-statistic. Convergent validity of self-reported "bone loss/deep pockets" and "loose teeth" was assessed; associations of self-report with RA disease characteristics were explored. Self-report performed similarly in RA and OA, with individual question specificity for periodontitis ≥68% and sensi...

Tissue engineering is a new methodology for addressing meniscal injury or loss. Synovium may be a... more Tissue engineering is a new methodology for addressing meniscal injury or loss. Synovium may be an ideal source of cells for in vitro meniscal fibrocartilage formation, however, favorable in vitro culture conditions for synovium must be established in order to achieve this goal. The objective of this study was to determine cellularity, cell distribution, and extracellular matrix (ECM) formation of equine fibroblast-like synoviocytes (FLS) cultured on synthetic scaffolds, for potential application in synovium-based meniscal tissue engineering. Scaffolds included open-cell poly-L-lactic acid (OPLA) sponges and polyglycolic acid (PGA) scaffolds cultured in static and dynamic culture conditions, and PGA scaffolds coated in poly-L-lactic (PLLA) in dynamic culture conditions. Materials and Methods. Equine FLS were seeded on OPLA and PGA scaffolds, and cultured in a static environment or in a rotating bioreactor for 12 days. Equine FLS were also seeded on PGA scaffolds coated in 2% or 4% PLLA and cultured in a rotating bioreactor for 14 and 21 days. Three scaffolds from each group were fixed, sectioned and stained with Masson's Trichrome, Safranin-O, and Hematoxylin and Eosin, and cell numbers and distribution were analyzed using computer image analysis. Three PGA and OPLA scaffolds from each culture condition were also analyzed for extracellular matrix (ECM) production via dimethylmethylene blue (sulfated glycosaminoglycan) assay and hydroxyproline (collagen) assay. PLLA coated PGA scaffolds were analyzed using double stranded DNA quantification as areflection of cellularity and confocal laser microscopy in a fluorescent cell viability assay. Results. The highest cellularity occurred in PGA constructs cultured in a rotating bioreactor, which also had a mean sulfated glycosaminoglycan content of 22.3 µg per scaffold. PGA constructs cultured in static conditions had the lowest cellularity. Cells had difficulty adhering to OPLA and the PLLA coating of PGA scaffolds; cellularity was inversely proportional to the concentration of PLLA used. PLLA coating did not prevent dissolution of the PGA scaffolds. All cell scaffold types and culture conditions produced non-uniform cellular distribution. How to cite this article Warnock et al. (2014), Culture of equine fibroblast-like synoviocytes on synthetic tissue scaffolds towards meniscal tissue engineering: a preliminary cell-seeding study. PeerJ 2:e353; DOI 10.7717/peerj.353

Journal of Tropical Medicine, 2014

A dengue fever surveillance study was conducted at three medical facilities located in the low-in... more A dengue fever surveillance study was conducted at three medical facilities located in the low-income district of San Javier in Medellin, Colombia. During March 2008 to 2009, 781 patients with fever regardless of chief complaint were recruited for acute dengue virus infection testing. Of the 781 tested, 73 (9.3%) were positive for dengue infection. Serotypes DENV-2 (77%) and -3 (23%) were detected by PCR. One patient met the diagnostic criteria for dengue hemorrhagic fever. Only 3 out of 73 (4.1%) febrile subjects testing positive for dengue infection were diagnosed with dengue fever by the treating physician. This study confirms dengue virus as an important cause of acute febrile illness in Medellin, Colombia, but it is difficult to diagnose without dengue diagnostic testing.

Arthritis & rheumatology (Hoboken, N.J.), 2014

To examine the degree to which shared risk factors explain the relationship of periodontitis (PD)... more To examine the degree to which shared risk factors explain the relationship of periodontitis (PD) to rheumatoid arthritis (RA) and to determine the associations of PD and Porphyromonas gingivalis with pathologic and clinical features of RA. Patients with RA (n = 287) and patients with osteoarthritis as disease controls (n = 330) underwent a standardized periodontal examination. The HLA-DRB1 status of all participants was imputed using single-nucleotide polymorphisms from the extended major histocompatibility complex. Circulating anti-P gingivalis antibodies were measured using an enzyme-linked immunosorbent assay, and subgingival plaque was assessed for the presence of P gingivalis using polymerase chain reaction (PCR). Associations of PD with RA were examined using multivariable regression. Presence of PD was more common in patients with RA and patients with anti-citrullinated protein antibody (ACPA)-positive RA (n = 240; determined using the anti-cyclic citrullinated peptide 2 [an...