Effect of nerve growth factor on adhesion and motional abilities of tumor cells and their correlation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect on adhesion and motion capbilities of adenoid cystic carcinoma (ACC), by detecting the expression of nerve growth factor (NGF), E-cadherin (E-cad) and S100A4 and the clinical significance in ACC tissues and analyzing the relationships between them with perineural invasion (PNI).</p><p><b>METHODS</b>The expression of NGF, E-cad and S100A4 in ACC was detected with the way of immunohistochemistry SP, and then analyzing the expression level of them in different pathological types and histological regions in statistical ways on the basis of their relation with clinical and pathological parameters.</p><p><b>RESULTS</b>The expression of NGF and S100A4 in PNI group [88% (23/26) and 77% (20/26)], was higher than that in NPNI group (8/16 and 7/16, P < 0.05), and a positive correlation between them was identified in PNI group (r = 0.316, P < 0.05). However the E-cad expression was lower in PNI group [31% (8/26), P < 0.05]. On the other hand it suggested a negative correlation with NGF (r = 0.385, P < 0.05) as well as that with S100A4 (r = -0.612, P = 0.000). The expression level of NGF in fasciculus [83% (25/30)] has significant deviation compared with it in distant tumor tissues [47% (14/30), P < 0.05].</p><p><b>CONCLUSIONS</b>In the PNI process of ACC, NGF plays important parts but not the only factor. It can increase the expression and activity of S100A4 but decrease E-cad expression through binding with its receptor. Thus, adhesion abilities of tumor cells was weakened and motional abilities was strengthen.</p>

The measurement of cutting forces in full crown preparation with three-dimensional transducer unit / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To measure the cutting forces applied by clinicians during preparing full crown and to provide basic data for the training of dentistry in a virtual reality.</p><p><b>METHODS</b>Each of six prosthodontists and six dental students prepared three extracted maxillary premolars. The cutting forces were measured with a three-dimensional transducer unit. Differences in cutting time and forces between groups were analyzed with independent-samples t-test.</p><p><b>RESULTS</b>The cutting forces varied in the range from 0.10 N to 4.90 N. The average cutting force (1.71 N) of four axial surfaces was higher than that (0.45 N) of occlusal surface (including functional cusp inclines) (P < 0.01). The cutting time by prosthodontists was shorter than that by the students (P < 0.05). Moreover, the vertical component of the cutting force was higher than the horizontal one (P < 0.01).</p><p><b>CONCLUSIONS</b>The magnitude of cutting forces could be greatly influenced by the motion direction and tendency of the handpiece. The data on cutting forces might serve as the foundation of cutting simulation algorithm for training in a virtual reality.</p>