Effects of mechanical stress on the formation and expression of Cbfalpha1 in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effects of mechanical stress on the formation and expression of core binding factor alpha1 (Cbfalpha1) in MG-63 cells cultured on titanium in vitro.</p><p><b>METHODS</b>MG-63 cells cultured on the titanium were subjected to a centrifugal force (2.205 N) 15 min per 4 hours and collected after 4, 8 and 12 hours. The formation and expression of Cbfalpha1 were examined by immunofluorescence staining and reverse transcription-polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Both the cells with or without centrifugal force created the fluorescence in the nucleus and the immunofluorescence intensity of Cbfalpha1 in MG-63 cells with centrifugal force were higher than those without centrifugal force (P<0.05). Meanwhile, both the cells with or without centrifugal force expressed the mRNA of Cbfalpha1 and the relative mRNA level of Cbfalpha1 in MG-63 cells with centrifugal force were higher than those without centrifugal force, and the differences were great significant (P<0.05).</p><p><b>CONCLUSION</b>Mechanical stress are beneficial to the formation and expression of Cbfalpha1.</p>

Influence of fluoride ion-implanted titanium on the formation of focal adhesion plaque in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the chemical composition of the modified surface of fluoride ion-implanted titanium and assess the effect on the formation of focal adhesion plaque in vitro.</p><p><b>METHODS</b>Pure commercial titanium discs were treated with fluoride ion implantation by plasma immersion ion implantation technique (PIII) and chemical composition and value of the surface modification layer were characterized by X-ray photoelectron spectrometer (XPS). In order to investigate the formation of focal adhesion plaque, MG-63 cells were seeded onto the surfaces of the modified Ti discs and quantified by morphometric analysis using an immunofluorescence microscope.</p><p><b>RESULTS</b>The full range XPS spectra and fitting results indicated that the surface of fluoride ion-implanted titanium was the mixture of titanium dioxide and titanium trifluoride. Meanwhile, the quantity of focal adhesion plaque on fluoride ion-implanted titanium was more than that on the non-implanted titanium after 6 hours' cell culture.</p><p><b>CONCLUSION</b>The XPS data revealed that the modified surface layer of fluoride ion-implanted titanium contained titanium dioxide and titanium trifluoride, which could enhance the formation of focal adhesion plaque.</p>

Three dimensional finite element stress analysis on superstructure of the fixed bridge supported by tooth-implant / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To reveal the stress distribution in the superstructure of fixed bridge supported by tooth-implant in the process of mastication for improvement of denture design.</p><p><b>METHODS</b>The stress distribution and displacement of the superstructure were studied and analyzed by means of CT Scan, CAD and three-dimensional finite element when various loads were applied.</p><p><b>RESULTS</b>(1) The stress distribution in abutments under oblique loads at forty-five degrees was uneven and the peak value was 4 - 6 times higher than that under vertical loads. Stress concentration occurred with significant compressive stress. (2) Compressive stress widely distributed in the middle area of occlusal surface of pontic, whose peak value under concentrated loads was significantly higher than that under disperse loads. The loading direction had no effect on the stress concentration. (3) The maximum displacement of implant abutment in medial-distal direction was greater than that of the neck of nature tooth.</p><p><b>CONCLUSIONS</b>The mechanic complications of superstructure could be prevented by reducing oblique loads and concentrated ones. It is certain that the further improvements of curve-resistance of pontics and press-resistance of abutments are available.</p>