[The study of the colorimetric characteristics of the cobalt-chrome alloys abutments covered by four different all-ceramic crowns by using dental spectrophotometer].

OBJECTIVE: This study aims to evaluate the optical data of the different sites of the cobalt-chrome (Co-Cr) alloy abutments covered by four different all-ceramic crowns and the color difference between the crowns and target tab using a digital dental spectrophotometer. METHODS: Ten Co-Cr alloy abutments were made and tried in four different groups of all-ceramic crowns, namely, Procera aluminia, Procera zirconia, Lava zirconia (Lava-Zir), and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic. The color data of the cervical, body, and incisal sites of the samples were recorded and analyzed by dental spectrophotometer. The CIE L*, a*, b* values were again measured after veneering. The color difference between the abutments covered by all-ceramic crowns and A2 dentine shade tab was evaluated. RESULTS: The L* and b* values of the abutments can be increased by all of the four groups of all-ceramic copings, but a* values were decreased in most groups. A statistical difference was observed among four groups. After being veneered, the L* values of all the copings declined slightly, and the values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔE of the crowns was below 4. CONCLUSION: Four ceramic copings were demonstrated to promote the lightness and hue of the alloy abutments effecttively. Though the colorimetric baseline of these copings was uneven, veneer porcelain can efficiently decrease the color difference between the samples and thee target.

Influence of repeated insertion-removal cycles on the force and magnetic flux leakage of magnetic attachments: an in vitro study.

STATEMENT OF PROBLEM: Magnetic attachments are widely used in overdentures and maxillofacial prostheses. Because the patient will routinely have to insert and remove a removable prosthesis, the retentive force and magnetic flux leakage of the magnetic attachments after repeated insertion and removal must be evaluated to assess their clinical performance. PURPOSE: The purpose of this in vitro study was to investigate the retentive force and flux leakage of magnetic attachments after repeated insertion and removal. MATERIAL AND METHODS: Magfit EX600W magnet-keeper combinations (n=5) were used in this study. After 5000, 10,000, and 20,000 insertion-removal cycles, the retentive force of the magnetic attachments was measured 5 times at a crosshead speed of 5 mm/min with a universal testing machine. Magnetic flux leakage at 3 positions (P1, the upper surface of the magnet; P2, the lower surface of the keeper; and P3, the lateral side of the magnetic attachment set) was evaluated with a gaussmeter. Data were statistically analyzed by 1-way ANOVA (α=.05). The morphology of the abraded surfaces for both the magnet and the keeper was observed with an optical microscope (5×). RESULTS: The mean retentive force decreased significantly after 5000, 10,000, and 20,000 insertion-removal movements (P<.05). Significant differences of flux leakage were also observed at P1 after 5000 cycles and 10,000 cycles, at P2 after 5000 cycles, and at P3 after 5000, 10,000, and 20,000 insertion-removal cycles (P < .05). However, no significant differences in flux leakage were evident after 20,000 cycles at P1 and 10,000 cycles and 20,000 cycles at P2. CONCLUSIONS: Repeated insertion and removal influenced the retentive force and magnetic flux leakage of the magnetic attachments. Retentive force decreased significantly after repeated insertion-removal cycles, whereas the variation of magnetic flux leakage depended on refitting cycles and positions of the magnetic attachments.

Adenovirus encoding BMP-7 immobilized on titanium surface exhibits local delivery ability and regulates osteoblast differentiation in vitro.

OBJECTIVE: The local delivery of growth factors such as bone morphogenetic protein-7 (BMP-7) into the tissues around dental implants may improve their osseointegration. We have designed a new method of attaching BMP-7 to a titanium surface and assessed both the retention of the BMP-7 and its effect on osteoblast differentiation. DESIGN: Adenoviral vector expressing BMP-7 was attached to dental titanium discs by hexon-specific antibodies in a type I collagen-avidin gel. FITC-labelled secondary antibody was used to measure the continuing adherence of the coating after repeated rinsing. Osteoblasts were harvested and seeded on the titanium discs. Gene transduction efficiency and targeting ability were assessed after 24h. Surface morphology was observed by SEM. Cell proliferation and alkaline phosphatase (ALP) activities were measured. RESULTS: The anti-adenohexon antibody adhered strongly to the collagen-avidin gels. BMP-7 gene expression was localized precisely to cells growing on the gels bound by the hexon-specific antibody. Osteoblasts on the titanium containing Ad-BMP-7 had a higher ALP activity than those without Ad-BMP-7. CONCLUSIONS: This study describes a novel technique for the precise attachment of BMP-7 to titanium surfaces. The process may enhance the osseointegration of dental implants.

hRpn13, a newly identified component of the 19S particle, regulates proliferation, differentiation, and function in the human osteoblast-like cell line MG63

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The 26S proteasome is a key component of the ubiquitin-proteasome system, a process responsible for the majority of cellular protein degradation. The function of the proteasomal ubiquitin receptor hRpn13, a component of the 26S proteasome, is not completely understood. To investigate the role of hRpn13 in the ubiquitin-proteasome system in osteoblasts, the effects of suppressing and overexpressing the hRpn13 gene on proliferation, differentiation, and function of human osteoblast-like MG63 cells were examined. After knockdown of hRpn13 by small interfering RNA, changes in osteoblast proliferation were evaluated by methyl-thiazolyl-tetrazolium assay. There was an increase in markers for osteoblast proliferation, specifically alkaline phosphatase activity, and elevated protein levels of osteocalcin, proliferating cell nuclear antigen (PCNA), and ubiquitin. Furthermore, hRpn13 knockdown also resulted in a decrease in the ratio between the gene expressions of RANKL and OPG, key players in the pathogenesis of bone diseases that influence the normal balance between bone formation and resorption. In contrast, overexpression of hRpn13 inhibited the proliferation of MG63 cells, and decreased alkaline phosphatase activity as well as protein levels of osteocalcin, PCNA, and ubiquitin while the ratio of RANKL to OPG expression increased. To confirm the function of hRpn13 in the ubiquitin-proteasome pathway, osteoblast proliferation enhancement and ubiquitin accumulation after hRpn2 knockdown was assessed. The results suggest that overexpression of hRpn13 negatively influences proliferation and osteogenic differentiation in MG63 cells. The evidence implies that hRpn13 modulates the influence of osteoblasts on osteoclasts by controlling the stability of regulatory proteins in osteoblasts. In summary, overexpression of hRpn13 promoted the activity of the ubiquitin-proteasome system (AU)

hRpn13, a newly identified component of the 19S particle, regulates proliferation, differentiation, and function in the human osteoblast-like cell line MG63. [corrected].

The 26S proteasome is a key component of the ubiquitin-proteasome system, a process responsible for the majority of cellular protein degradation. The function of the proteasomal ubiquitin receptor hRpn13, a component of the 26S proteasome, is not completely understood. To investigate the role of hRpn13 in the ubiquitin-proteasome system in osteoblasts, the effects of suppressing and overexpressing the hRpn13 gene on proliferation, differentiation, and function of human osteoblast-like MG63 cells were examined. After knockdown of hRpn13 by small interfering RNA, changes in osteoblast proliferation were evaluated by methyl-thiazolyl-tetrazolium assay. There was an increase in markers for osteoblast proliferation, specifically alkaline phosphatase activity, and elevated protein levels of osteocalcin, proliferating cell nuclear antigen (PCNA), and ubiquitin. Furthermore, hRpn13 knockdown also resulted in a decrease in the ratio between the gene expressions of RANKL and OPG, key players in the pathogenesis of bone diseases that influence the normal balance between bone formation and resorption. In contrast, overexpression of hRpn13 inhibited the proliferation of MG63 cells, and decreased alkaline phosphatase activity as well as protein levels of osteocalcin, PCNA, and ubiquitin while the ratio of RANKL to OPG expression increased. To confirm the function of hRpn13 in the ubiquitin-proteasome pathway, osteoblast proliferation enhancement and ubiquitin accumulation after hRpn2 knockdown was assessed. The results suggest that overexpression of hRpn13 negatively influences proliferation and osteogenic differentiation in MG63 cells. The evidence implies that hRpn13 modulates the influence of osteoblasts on osteoclasts by controlling the stability of regulatory proteins in osteoblasts. In summary, overexpression of hRpn13 promoted the activity of the ubiquitin-proteasome system.

Flavokawain B induces apoptosis of human oral adenoid cystic cancer ACC-2 cells via up-regulation of Bim and down-regulation of Bcl-2 expression.

Novel effective drugs are still urgently needed in the prevention and treatment of oral adenoid cystic carcinoma (ACC). In this study, we have assessed the antitumor potential and molecular mechanisms of flavokawain B (FKB) as a kava chalcone on the ACC-2 cell line in vitro. The results demonstrated that FKB could significantly inhibit the cell proliferation of ACC-2 in a dose-dependent manner that was associated with induced apoptosis and cell cycle G2-M arrest, and the half maximal inhibitory concentration (IC50) of flavokawain-B treatment for 48 h was estimated to be 4.69 ± 0.43 µmol/L. Mechanistically, FKB could induce the release of cytochrome c from mitochondria into the cytosol, and activate the cleavage of caspase-3 and, eventually, the poly(ADP-ribose) polymerase (PARP), in a dose-dependent manner, leading to marked apoptotic effect of ACC-2 cells. The apoptotic action of FKB was associated with the increased expression of proapoptotic proteins: Bim, Bax, Bak and a decreased expression of antiapoptotic Bcl-2. Among them, Bim expression was significantly induced by FKB, and knockdown of Bim expression by short-hairpin RNAs attenuated the inhibitory effect induced by FKB on ACC-2 cells. These results suggest Bim may be one of the potential transcriptional targets, and suggests the potential usefulness of FKB for the prevention and treatment of ACC.

[Osteoblastic early attachment onto the surface of bioadhesive peptide modified pure titanium].

OBJECTIVE: To investigate the long-term integrity and the biological function of interface between the bioadhesive peptide modified implant surface and peri-implant tissue. METHODS: A short bioadhesive peptide containing Glycine-Tyrosine-Arginine-Glycine-Asparticacid-Serine (GYRGDS) sequence was immobilized onto the titanium implant surface by means of sol-gel coating technique and self-assembled monolayers (SAM). The chemical composition and organic functional groups on the titanium surfaces were characterized using XPS (X-ray photoelectron spectroscopy) and FTIR (Fourier transform infrared spectrometer). The adhesive strength and stability of osteoblasts on various implant surfaces were compared under flow condition. RESULTS: The results showed that alkali/hot water aging treatment could apparently improve the content of -OH functional groups of titanium surface. The chemical reactive Ti-O-Ti bonding at the surface of titanium played a vital role in inducing the formation of organosilane SAM. GYRGDS peptide can be covalently grafted onto the surface of titanium by SAM technique. The resistance of freshly adherent osteoblasts to detachment by flow was shear time dependent. When the four groups were compared under the same flow stress condition (2.05 Pa) at three specific time spans (30 min, 1 h, 2 h), the cells retention rates in GYRGDS-grafted groups were 93.0%, 54.4%, 34.4% respectively and were much higher than those in non-coated groups. CONCLUSIONS: It was suggested that GYRGDS might have positive effects on maintaining stability and adherence of cells onto the substrates under flow condition.

[Experimental study on the reconstruction of mandibular defects with sinboneHT bone replacement in rabbits].

OBJECTIVE: After sinboneHT bone replacement (SBR) was implanted in animals, to evaluate the biocompatibility of SBR and compounded in autogenetic bone in the proportion of one to one in order to prepare for the clinical applications in the future. METHODS: Bone defects of 10 mm x l0 mm x 2 mm was made at the mandibular of rabbits, then SBR with different granule diameter and autogenetic bone was compounded in the proportion of being applied in the left defects, while autogenetic bone was implanted in the right defects and nothing was used in the right reformed defects. Animals were sacrificed at 2, 4 and 8 weeks respectively. The biologic capacity was evaluated with anatomy, X-rays studies and histology. RESULTS: SBR has better biocompatibility, which can effectively accelerate the reconstruction of bone defects and help the new bone by being compounded with autogenetic bone. It provides the appropriate scaffold or template which would allow cellular infiltration, attachment and multiplication. CONCLUSION: SBR is a kind of bone substitute material with good biocompatibility. SBR compounded with self-bone has a better regeneration function.

[Influence of multiple sintering on wear behavior of Cercon veneering ceramic].

OBJECTIVE: To investigate the influence of multiple sintering on wear behavior of Cercon veneering ceramic. METHODS: Samples were fabricated according to the manufacture's requirement for different sintering times (1, 3, 5, 7 times). The wear test was operated with a modified MM-200 friction and wear machine in vitro. The wear scars were characterized by scanning electron microscope (SEM) and atomic force microscopy (AFM). RESULTS: With the sintering times increasing, the wear scar width became larger. The correlation was significant at the 0.01 level. Significant difference was observed in wear scar width among different samples (P < 0.05). SEM and AFM results showed that veneering ceramic wear facets demonstrated grooves characteristic of abrasive wear. CONCLUSION: Multiple sintering can decrease the wear ability of Cercon veneer, and the wear pattern has the tendency to severe wear.

[Bi-axial flexure strength and fracture mode of alumina glass-infiltrated core/veneer ceramic composites].

PURPOSE: To determine the bi-axial flexural strength and fracture mode of bilayered alumina glass-infiltrated core and the veneering porcelain. METHODS: Forty disk specimens were made from alumina glass-infiltrated core (HSDC-A) and veneer porcelain (Vintage AL), and equally divided into four groups as follows: monolithic specimens of veneer(MV),monolithic specimens of core material(MC),bilayered specimens with the veneer on top (BC) and bilayered specimens with core material on top(BV). Mean flexure strength, standard deviation and associated Weibull modulus were determined using bi-axial flexure (ball-on-ring) for each group. The results were analyzed with one-way ANOVA and the Weibull distribution with SPSS 13.0 software package. Both optical and scanning electron microscopy were employed for identification of the fracture mode and origin. RESULTS: The strength in the group MC and BC were significantly stronger than that in the group MV and BV. The frequency of specimen delamination, Hertzian cone formation and sub-critical radial cracking in the bilayered discs were dependent on the surface loaded in tension. CONCLUSION: Material which lies on the bottom surface dictates the strength and fracture mode of the specimens. Supported by Shenzhen Municipal Technological Project (Grant No.200903082).

[Effect of different dynamic mechanical strain on the proliferation and synthetic function of human periodontal ligament fibroblasts in vitro].

OBJECTIVE: To study the changes in the proliferation and synthetic function of human periodontal ligament fibroblasts (HPDLF) in response to dynamic mechanical strains of different modes, magnitudes and durations. METHODS: Using a 4-point bending system, the effect of dynamic mechanical strains of different modes, magnitudes and durations on the proliferation of HPDLF was investigated by analyzing the cell cycle changes with flow cytometry (FCM), and the total protein level and the activity of alkaline phosphatase (ALP) in HPDLF were assayed by quantitative analysis. RESULTS: The percentage of G(0)/G(1) cell decreased, S phase cells increased, and the proliferation index (PI), total protein level and activity of ALP were augmented significantly in response to dynamic mechanical micro-strains. These changes showed close correlations to the magnitude and duration of the strain. The mode of strain caused significant changes in G(0)/G(1), S, and G(2)/M phase cell percentages as well as the PI, total protein level and ALP activity of the cells. In the gradient strain group, the cell proliferation activity, total protein level and ALP activity were obviously higher than those in 1000 and 4000 microstrain groups. CONCLUSION: The changes in the proliferation and synthetic function of HPDLF are closely correlated to the mode, magnitude and duration of the strains.

Fluoridated hydroxyapatite coatings on titanium obtained by electrochemical deposition.

Hydroxyapatite (HA) and fluoridated hydroxyapatite (FHA) coatings were deposited on titanium substrates using an electrochemical technique. Different concentrations of F(-) ions were incorporated into the apatite structure by adding NaF into the electrolyte. Typical apatite structures were obtained for all the coatings after electrodeposition and subsequent post-treatment, including alkaline immersion and vacuum calcination. The coatings were uniform and dense, with a thickness of approximately 5 microm. When the F-concentration was higher than 0.012 M in the electrolyte, a saturation of F in the coating occurred and the F/Ca ratio in the coatings became almost constant (F/Ca ratio=0.125). The FHA coatings showed higher bonding strength and lower dissolution rate than HA coating, particularly for those with a fluoridation level of 0.5-0.625. Compared with pure Ti, FHA and HA coatings exhibited higher biological affinity like cell proliferation and alkaline phosphatase activity. Regarding clinical application, it is suggested that a moderate content of F, such as Ca(5)(PO(4))(3)(OH)(0.375-0.5)F(0.5-0.625), be most suitable as a compromise among cell attachment, cell proliferation, apatite deposition and dissolution resistance.

Fluoridated hydroxyapatite/titanium dioxide nanocomposite coating fabricated by a modified electrochemical deposition.

Fluoridated hydroxyapatite/titanium dioxide nanocomposite coating was successfully fabricated by a modified electrochemical deposition technique. F(-) ions, nanoscaled TiO(2) particles and 6% H(2)O(2) was added into the electrolyte, and ultrasonication was also performed to prepare this nanocomposite coating. The microstructure, phase composition, dissolution rate, bonding strength and in vitro cellular responses of the composite coating were investigated. The results show that the composite coating was uniform and dense owing to the effects of H(2)O(2) and ultrasonication. The thickness of the composite coating was ~5 mum and scanning electron microscopy revealed that nanoscaled TiO(2) particles were imbedded uniformly between FHA crystals. The addition of F(-) and TiO(2) reduced the crystallite size and increased the crystallinity of HA in FHA/TiO(2) composite coating. In addition, the composite coating shows higher bonding strength and lower dissolution rate than pure HA coating, and the in vitro bioactivity of FHA/TiO(2) composite coating was not affected as compared with pure HA coating.

[Regulation of collagen type I and fibronectin mRNA expression by mechanical stress in cultured human periodontal ligament fibroblasts].

OBJECTIVE: To investigate the effect of different dynamic tensional and compressive stress on the mRNA expression of collagen type I and fibronectin in cultured human periodontal ligament fibroblasts (hPDLF), and explore the regularity of functional change in hPDLF. METHODS: A new cyclic strain loading apparatus was used for mechanically loading. Cells cultured in vitro were loaded with three levels (1000 microstrain, 2000 microstrain, 4000 microstrain) of tensional and compressive forces and collected at different time (0 h, 0.5 h, 1 h, 4 h, 8 h,12 h) course after strain loading. The quantity of collagen type I and fibronectin mRNA was analyzed by means of quantitative real-time PCR with special primers of up- and down-regulated genes. Data were analyzed using SPSS version 10.0 software. RESULTS: Different magnitude and different kinds of mechanical forces as well as the force application time significantly changed the expression of collagen type I and fibronectin mRNA in hPDLF. CONCLUSIONS: Dynamic mechanical forces could regulate the expression of collagen type I and fibronectin mRNA in hPDLF. Collagen type I and fibronectin participated in the mechanical signal transduction in human periodontal ligament fibroblasts.

The possible role of estrogen in the incidence of temporomandibular disorders.

Epidemiologic literatures suggest that temporomandibular joint disorders (TMD) are more prevalent in women than in men. It is affecting approximately 7-15% of the adult population in North America, and 80% of patients treated for TMD are women. The severity of symptoms is also related to the age of the patients. The gender and age distribution of TMD suggests a possible link between its pathogenesis and estrogen. It has been reported that estrogen could influence the development, restitution and metabolism of the temporomandibular joint and associated structures such as bone, cartilage and articular disc. Estrogen can also influence the regulative mechanism of pain. In this article, we will use the hypothesis that the overwhelming majority of patients treated for temporomandibular disorders are women and use the available literature to examine the role of estrogens in TMD.

[Regulation of integrin beta1 mRNA expression by mechanical stress in human periodontal ligament fibroblasts].

OBJECTIVE: To investigate the effect of different kinds of mechanical stress on the mRNA expression of integrin beta1 subunit in cultured human periodontal ligament fibroblasts (hPDLF). METHODS: To scalp and remove the periodontal ligament attached to the mid-third part of the fresh root of young premolars extracted for the cause of orthodontics. Cultured hPDLF by the method of digesting by I-type collagenase combining with tissue adhering. Then hPDLF was isolated and purified by cells passage. The sixth passage's cells were selected to be loaded. A new cyclic strain loading apparatus. Forcel four point bending device was used for mechanically loading. Cells were loaded by three levels (1000, 2000, 4000 microstrain) of tensional and compressive forces and collected at different times (0, 0.5, 1, 4, 8, 12 h) course after strain loading. The quantity of integrin beta1 mRNA in every group was analyzed by means of quantitative real-time PCR with the special primers of up- and down-regulated genes. RESULTS: Dynamic mechanical forces down-regulated the expression of integrin beta1 subunit mRNA in hPDLF and the difference in groups by different magnitude, different kinds, and different time of mechanical forces loading were statistically significant. The stronger stimulated forces, the more down-regulated expression. Compression down-regulated the expression of integrin beta1 subunit mRNA more than tension did. CONCLUSION: Dynamic mechanical forces could regulate the expression of integrin beta1 subunit mRNA. The difference among all the groups by different magnitudes, different kinds, and different time of mechanical forces loading were statistically significant.

Translucency of newly extracted maxillary central incisors at nine locations.

STATEMENT OF PROBLEM: In addition to color, translucency is one of the primary factors influencing the esthetics of a dental prosthesis. Due to difficulties in measuring the translucency of natural teeth, minimal data are available. PURPOSE: The purpose of this study was to measure the translucency of newly extracted maxillary central incisors and analyze the relationship between translucency, anatomic location, and age. MATERIAL AND METHODS: The translucency of 32 newly extracted maxillary central incisors was measured with a spectrocolorimeter (PR-650) at 9 locations on the tooth crown. These locations were identified by dividing the tooth incisally to cervically and medially to laterally in equal dimensions. The relationships between transmittance, locations, and age were analyzed by univariate analysis of variance (alpha=.05). RESULTS: The transmittance of maxillary central incisors ranged from 0.13% to 0.65%, which decreased from incisal to cervical (P<.05). Age also affected transmittance in certain locations of the crown; older teeth demonstrated higher transmittance (P<.05). CONCLUSIONS: Transmittance of the maxillary central incisor was variable at different locations of the crown and was positively correlated with age.

[Determination and Weibull analysis of the strength of dental veneering porcelains].

OBJECTIVE: To determine the strength of the veneering porcelain stored in artificial saliva. METHODS: Standard beams with a size of 3 mm x 2 mm x 20 mm made from the body, incisal, and translucent porcelains of SHOFU Vintage were stored in the artificial saliva for 30 days. Twenty samples from each material were tested for the strength by the 3-point flexural test at a crosshead speed of 0.5 mm. The data were analyzed by the two-parameter Weibull method. RESULTS: The strength, Weibull modulus (m) and characterization strength (male0) were (75.5 +/- 5.6) MPa, 17.3, and 77.6 MPa for Body porcelain, respectively; (73.6 +/- 5.0) MPa, 16.5, and 76.0 MPa for incisal porcelain, respectively; and (72.9 +/- 4.5) MPa, 16.1, and 75. 5 MPa for translucent porcelain, respectively. CONCLUSION: There are no differences in strength between the three dental porcelains. Weibull analysis describes the strength of the porcelains better than the average and standard deviation.

[Effect of simulating static magnetic field of magnetic attachment on osteoblastic morphology and surface ultrastructure].

OBJECTIVE: To investigate effects of the static magnetic field (SMF) generated by dental magnetic attachment on osteoblastic morphology and surface ultrastructure. METHODS: The in vitro cultured rat osteoblasts were exposed continuously to 12.5 mT, 125 mT, and 250 mT static magnetic fields for 1, 3, 5, and 7 days. After exposed in SMF, osteoblasts were observed under a phase contrast microscope, and then HE stained and observed under a light microscope. In addition, the cells were observed under a scanning electron microscope (SEM). RESULTS: By continuous exposure, the different intensities of SMF exposure did not change the vital osteoblast growth pattern or distribution. The SEM photos showed that there were certain changes in cellular microstructures for osteoblasts after exposed to 12.5 mT for 5 to 7 days, as well as 125 mT and 250 mT for 3 to 7 days. The more exposure time increased, the more microvesicles on the surfaces of cells were observed. CONCLUSIONS: Continuous SMF-stimulation could not affect the shape, distribution, and growth pattern of osteoblasts. The SMF of magnetic attachments could lead to certain changes in surface ultrastructures of osteoblasts in this study.

Magnetic fields of 10mT and 120mT change cell shape and structure of F-actins of periodontal ligament cells.

Dental magnetic attachments, usually applied locally to oral cavities, produce stray fields (flux leakage) spreading in adjacent tissues. It has been found that human periodontal ligament (PDL) cells change their geometry and the structure of their cytoskeleton F-actins when the cell cultures are exposed to B-field strengths of B = 10mT and 120mT, respectively, which are similar to those generated by dental magnetic attachments. Analytically, after long-time exposures to B-fields for 12h, 36 h and 60 h, respectively, cytoskeleton F-actins are labeled with a fluorescent dye and observed under a laser scanning confocal microscope. The geometrical cell parameters of cell length and cell width and the fluorescence emission of labeled F-actins, respectively, were determined and subjected to an automatic image analysis using a special software. The results on cell shrinkage and filament reorganizations were statistically analyzed by the program ANOVA (P < 0.05). It was found that only long-time (hours) exposure to high fields in the order of 0.1T may produce tissue irritations during long-time medical treatments using open- and closed-field dental magnetic attachments.