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H J Kim,
S H Kim,
M S Kim,
E J Lee,
H G Oh,
W M Oh,
S W Park,
W J Kim,
G J Lee,
N G Choi,
J T Koh,
D B Dinh,
R R Hardin,
K Johnson,
V L Sylvia, J P Schmitz,
D D Dean
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ABSTRACT: Osteoblast response to Ti implants depends not only on the chemistry of the implant but also on the physical properties of the implant surface, such as microtopography and roughness. This study was undertaken to examine early changes in cell morphology and gene expression during the early phase of osteoblast interaction with titanium alloy (Ti-6Al-4V) surfaces of two different roughnesses. MG63 osteoblast-like cells were cultured for 2, 6, 24, and 72 h on smooth (Ra=0.18+/-0.03 microm) and rough (Ra=2.95+/-0.23 microm) Ti-6Al-4V surfaces. Changes in cell proliferation were assessed by measuring cell number after 72 h in culture. Morphological characteristics were observed by scanning electron microscopy after 2, 6, and 24 h of culture. Changes in gene expression for extracellular signal-regulated kinase 2 (Erk2), type I collagen (alpha2[I] collagen), phospholipase C-gamma2 (Plc-gamma2), and beta-actin were measured by RT-PCR after 6 and 24 h in culture. Cell number was significantly higher on the smooth surface. In scanning electron micrographs, cells on smooth Ti-6Al-4V were spherical and raised up from the surface after 2 h in culture. In contrast, cells on the rough surface adopted an irregular, elongated shape that spanned across pits in the surface. At 24 h, cells on the smooth surface had flattened, become elongate, and covered the surface. In contrast, cells on the rough surface appeared more differentiated in shape and the margins of the cells were irregular, with many processes extending out, following the contour of the surface. Of the genes examined, only Erk2 and beta-actin showed a change in expression with surface roughness. Both genes were upregulated (p<0.05) on the rough surface at 6 h. These results indicate that Ti-6Al-4V surface roughness affects osteoblast proliferation, morphology, and gene expression, and that these effects can be measured after periods as short as 2-6 h.
Journal of Biomedical Materials Research Part A 09/2005; 74(3):366-73. · 2.63 Impact Factor
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Journal of Oral and Maxillofacial Surgery 10/2001; 59(9):1119-21. · 1.64 Impact Factor
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ABSTRACT: This study investigates the dissolution of calcium (Ca2+), phosphorus (P5+), and the transverse strength of commercially available calcium phosphate (CaP) bone cements after immersion in fetal bovine serum and a tissue fluid substitute. It was observed that although a continual increase in Ca2+ and P5+ dissolution was detected in all three test media throughout the 21-day period, no statistical difference existed in the overall Ca2+ release after incubating the cements in the three different media. However, P5+ release after immersion in Tris solution (0.37 +/- 0.02 microgram/mm2) and fetal bovine serum solution (0.347 +/- 0.06 microgram/mm2) was significantly higher when compared with P5+ released (0.03 +/- 0.002 microgram/mm2) in tissue fluid substitute. In addition, no significant difference in transverse strength was observed for samples immersed in the three solutions during the 21-day period. However, the transverse strength for immersed CaP cement bars at 37 degrees C was statistically greater than non-immersed bars set aside at room temperature for the 21-day period (7.78 +/- 1.82 N and 3.19 +/- 0.93 N, respectively). It was concluded from this study that the transverse strength of the CaP bone cements was not significantly affected by the dissolution process but by the temperature at which the bone cement was exposed.
Implant Dentistry 02/2001; 10(2):143-8. · 1.05 Impact Factor
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ABSTRACT: In the last 3 decades, much progress has been made in the development of biodegradable osteosyntheses. Despite this progress, these materials are still only used in small numbers, and the scope of their application has been limited. The limitations of biodegradable osteosyntheses mainly are related to problems with their mechanical properties and, in particular, biocompatibility. These problems need to be solved so that biodegradable osteosyntheses can perform up to their full potential and thus, eventually, make their general clinical application routine. This paper presents a historical perspective on the development of biodegradable osteosyntheses, discusses the successful developmental achievements and the still-existing problems, and gives a perspective on their future development.
Tissue Engineering 09/2000; 6(4):413-24. · 4.02 Impact Factor
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Journal of Oral and Maxillofacial Surgery 09/2000; 58(8):888-93. · 1.64 Impact Factor
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ABSTRACT: This article describes a technique for the retrieval of polymeric particulate debris following advanced hydrolytic in vitro degradation of a biodegradable polymer and presents the results of the subsequent particle analysis. Granular 80/20 poly(L-lactide-co-glycolide) (PLG) was degraded in distilled, deionized water in Pyrextrade mark test tubes at 80 degrees C for 6 weeks. Subsequently, a density gradient was created by layering isopropanol over the water, followed by a 48-h incubation. Two opaque layers formed in the PLG tubes, which were removed and filtered through 0.2-micrometer polycarbonate membrane filters. In addition, Fourier transform IR spectroscopy (FTIR) was performed to confirm the presence of polymer in the removed layers. The filters were gold sputter coated, and scanning electron microscopy (SEM) images were made. FTIR analysis confirmed that the removed material was PLG. SEM images of the extracts from the upper (lowest density) opaque layer showed a fine, powderlike substance and globular structures of 500-750 nm. The SEM images of the lower (highest density) opaque layer showed particles with a crystalline-like morphology ranging in size from 4 to 30 micrometer. Particulate PLG debris generated with the described technique can be useful for further studies of its biological role in complications associated with poly(alpha-hydroxy)ester implants. This study shows the presence of very persistent nano- and microparticles in the degradation pathway of PLG.
Journal of Biomedical Materials Research 05/2000; 50(1):59-66.
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ABSTRACT: The purposes of this study were 1) to determine whether iron concentrations detected in temporomandibular joint (TMJ) lavage fluid samples obtained from symptomatic patients are sufficient to catalyze the degradation of specific extracellular matrix (ECM) molecules in vitro, and 2) to provide evidence of oxidative stress in symptomatic TMJs by the detection of protein carbonyls in lavage fluids.
Iron concentrations in TMJ lavage samples (19 joints in 14 patients) were determined colorimetrically, and the ability of the sample to produce free radicals in the presence of hydrogen peroxide was determined with the chromogen 2,2'-azinobis (3-ethylbenzothizoline-6-sulfonic acid), diammonium salt (ABTS). The presence of oxidized proteins was measured fluorimetrically using Bodipy FL hydrazide (Molecular Probes, Eugene, OR). Degradation of fibronectin was visualized by Western blot. Relative susceptibilities of fibronectin and collagen I to free radical cleavage were measured with the Fenton reaction.
Redox-active iron concentration in lavage samples was found to be as high as 3.66 micromol/L. A 70-kd protein band, presumed to be albumin, was found to contain higher levels of carbonyls than peripheral serum albumin, which correlated with a greater degree of oxidative damage. Fibronectin was found to be more susceptible than collagen I to free radical degradation, and fragments of the former were found in the lavage. The TMJ lavage fluid was capable of producing free radicals in the presence of peroxide.
Circumstantial evidence is provided that the presence of modified and cleaved proteins isolated from lavage of symptomatic TMJs may have been subjected to oxidative stress.
Journal of Oral and Maxillofacial Surgery 04/2000; 58(3):302-8; discussion 309. · 1.64 Impact Factor
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ABSTRACT: The calcium phosphate cements (CPCs) are rapidly emerging as a new technology in craniofacial surgery and will soon impact many areas of orthopedic and maxillofacial reconstructive surgery as well. These materials are, in many ways, substantially different from the previously marketed dense, crystalline, hydroxyapatite (HA) ceramic materials of the 1980s. The CPCs are blends of amorphous and crystalline calcium phosphate compounds and set to produce HA. These materials 1) have x-ray diffraction spectra similar to the mineral phase of bone, 2) set endothermically at body temperature, 3) are capable of being injected into fractures or bone defects, 4) have compressive strengths equal to or greater than bone, 5) form chemical bonds to the host bone, and 6) may exhibit osteoconductive properties. This review provides an overall commentary on the different types of CPCs, emphasizing those materials currently on the market or soon to emerge in the marketplace.
Journal of Oral and Maxillofacial Surgery 10/1999; 57(9):1122-6. · 1.64 Impact Factor
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ABSTRACT: Objective measuring of globe position is not a universal practice in the management of orbital trauma. Few studies in the literature advocate its routine use.
The Hertel exophthalmometer is the most widely used instrument; however, in trauma involving the lateral orbital rim (e.g., in zygoma fractures), the results are inaccurate because the displacement of the zygomatic bone interferes with its reference point on the lateral orbital rim. A more recent measuring device, the Naugle orbitometer, was introduced in 1992. It uses the superior orbital rim (frontal bar) and inferior orbital rim (malar eminence) as reference points.
This article reports experience with this instrument in objective measuring the position of the globe in orbital trauma. These measurements are used 1) to monitor fractures that may not require repair but should be followed and observed for dystopia or enophthalmos, 2) to determine the adequacy of fracture repair, and 3) to determine the volume adjustment required for correcting enophthalmos. Future studies will be directed to compare the accuracy of Naugle and Hertel exophthalmometers.
The Journal of cranio-maxillofacial trauma 02/1999; 5(1):13-8.
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ABSTRACT: In this study, lavage fluid was fractionated from the superior joint space in patients with temporomandibular joint (TMJ) dysfunction. A hide powder azure protease assay was used to assess protease activity in lavage fluid. No correlation between a patient's pain and the level of protease activity was demonstrated. Latent as well as active proteases were detected in the sample lavage fluid. Latent matrix metalloproteinases (MMPs) were activated using trypsin. Stromelysin-1 was detected in an active form in lavage fluid by immunozymography. The presence of high molecular weight species with protease activity was also demonstrated. This study validates the presence of stromelysin-1 as well as other MMPs in TMJ lavage fluid and proposes a mechanism for their physiologic activation.
International Journal of Oral and Maxillofacial Surgery 11/1998; 27(5):397-403. · 1.51 Impact Factor
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Biomedical Engineering Conference, 1998. Proceedings of the 17th Southern; 03/1998
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ABSTRACT: The molecular events that underlie degenerative temporomandibular joint diseases are poorly understood. Recent studies have provided evidence that a variety of molecular species, including cytokines, matrix degrading enzymes, neuropeptides, and arachidonic acid catabolites may be involved. This paper advances the theory that mechanical stresses lead to the accumulation of damaging free radicals in affected articular tissues of susceptible individuals. This condition is called oxidative stress. The authors postulate mechanisms that may be involved in the production of free radicals in the temporomandibular joint and in the subsequent induction of molecular events that may amplify damage of articular tissues initiated by free radicals. If the proposed model is correct, then future therapeutic strategies directed at the control of oxidative stress could be effective in the management of degenerative temporomandibular joint diseases.
Journal of Oral and Maxillofacial Surgery 03/1998; 56(2):214-23. · 1.64 Impact Factor
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ABSTRACT: Traditional histology identifies three components of bone: cells, an extracellular mineralized organic matrix, and a lymphatic-vascular component. Specialized bone cells known as osteoblasts promote bone regeneration. Clinically, this property has been exploited by surgeons with autografts and bank bone preparations to restore deficient form and function to almost every aspect of the skeleton. Unfortunately, these therapies can be inadequate for patients with panskeletal trauma. Therefore, a suitable alternative may be a laboratory-derived product consisting of a vulnerary factor and delivery system. The integration of a laboratory-engineered product in an osseous wound environment is a formidable challenge demanding a keen appreciation of the product's macrophysiologic roles in wound healing biology. Consequently, the purposes for this paper are 1) to define briefly macrophysiology relevant to a delivery system for vulnerary molecules and bone regeneration; 2) to review a key family of bone regenerating molecules, the bone morphogenetic proteins (BMPs); and 3) to relate delivery system engineering with bone regeneration.
Annals of the New York Academy of Sciences 01/1998; 831:427-37. · 3.15 Impact Factor
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Tissue Engineering - TISSUE ENG. 01/1998; 4(1):53-63.
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ABSTRACT: The purpose of this study was to test the hypotheses that hemoglobin recovered by arthrocentesis of the superior joint space of symptomatic human temporomandibular joints (TMJs) is "old" hemoglobin that was not iatrogenically introduced by the arthrocentesis procedure and that it exists primarily in a non-native or denatured conformation state that may be sufficient to catalyze a reaction leading to the formation of damaging free radicals.
Twelve patients diagnosed with a unilateral articular disk displacement with TMJ arthralgia were included in this study. A superior joint space arthrocentesis was performed in the affected TMJ, and outflow lavage volumes were collected in serial 2-mL fractions. alpha-Hemoglobin/albumin ratios were determined for each collected fraction by densitometric analysis of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In addition, 3,3',5,5'-tetramethylbenzidine (TMB) assays were used to determine the conformation state of the recovered hemoglobin.
High alpha-hemoglobin/albumin ratios relative to that of serum (at least 10 times greater) were observed in several collected fractions of TMJ lavage fluid in all subjects studied. Because the tissue half-life of hemoglobin is significantly longer than that of albumin, these findings indicate that much of the hemoglobin recovered by arthrocentesis of symptomatic TMJs represents "old" hemoglobin that was present in the joint before the procedure. Furthermore, based on reactivity in the TMB assay, we estimate that up to 89% of the alpha-hemoglobin present in TMJ lavage fluid samples exists in a denatured state.
These results indicate that a significant amount of hemoglobin recovered by arthrocentesis of symptomatic TMJs exists in a denatured state and was present in the joint before arthrocentesis. Recent studies suggest that denatured hemoglobin may contribute redox active iron that can catalyze a reaction, leading to the formation of damaging free radicals. Such a process may represent one of the earliest molecular events involved in the pathogenesis of degenerative TMJ disease.
Journal of Oral and Maxillofacial Surgery 12/1997; 55(11):1242-8; discussion 1249. · 1.64 Impact Factor
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ABSTRACT: The purpose of this study was to determine whether specific proteins recovered from human temporomandibular joints (TMJs) by superior space arthrocentesis are eluted at different outflow volumes.
Twenty subjects with unilateral TMJ pain and restricted mandibular range of motion underwent superior space arthrocentesis of the affected TMJ. Sixteen serial fractions of the arthrocentesis outflow volume were collected for analysis. The protein content of each fraction was determined by a BCA protein assay and analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In addition, samples from each collected fraction were assayed for protease activity.
The average amount of protein recovered in the total 32 mL of collected arthrocentesis fluid was 1.5 mg (0.72 to 2.1 mg). Significant differences (P = .03) in total protein recovered from arthrocentesis fluid were observed between males (0.824 +/- 0.43 mg/20 mL) and females (1.389 +/- 0.54 mg/20 mL). In general, protein concentration declined serially in collected TMJ lavage fluid fractions. Specific proteins and proteases detected in the lavage fluid were eluted at different outflow volumes.
Although specific proteins are eluted from the TMJ at different outflow volumes during arthrocentesis, the procedure effectively reduces the protein concentration of the lavage fluid in a volume-dependent manner. Based on empirical assumptions, it is estimated that approximately 100 mL of total arthrocentesis volume is sufficient for a therapeutic lavage of the superior joint space of the human TMJ.
Journal of Oral and Maxillofacial Surgery 08/1997; 55(7):709-16; discussion 716-7. · 1.64 Impact Factor
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Journal of Oral and Maxillofacial Surgery 05/1997; 55(4):403-8. · 1.64 Impact Factor
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Journal of Oral and Maxillofacial Surgery 03/1997; 55(2):175-9. · 1.64 Impact Factor
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Journal of Oral and Maxillofacial Surgery 02/1997; 55(1):91-3; discussion 93-4. · 1.64 Impact Factor
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ABSTRACT: Hyoid bone suspension with inferior myotomy has been shown to be a successful technique in the treatment of obstructive sleep apnea. However, little mention is made in the literature concerning the details of the surgical procedure. Anatomic details have been given even less attention. This article addresses the regional anatomy, surgical technique, and materials for suspension of the hyoid bone, along with newer modifications of the procedure. Potential risks and complications are also discussed.
Journal of Oral and Maxillofacial Surgery 12/1996; 54(11):1339-45. · 1.64 Impact Factor
