Effect of lipopolysaccharide on the stromal cell-derived factor-1 expression in human stem cells from apical papilla / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the expression of stromal cell-derived factor-1 (SDF-1) in human stem cells from apical papilla (SCAP), and to evaluate the effect of lipopolysaccharide (LPS) on SDF-1 expression by SCAP.</p><p><b>METHODS</b>SCAP were isolated from dental papilla of human immature third molars. The expression of SDF-1 was evaluated by reverse transcription-PCR (RT-PCR). After SCAP being exposed to different concentrations (0.1, 1.0, 10 mg/L) of LPS for 24 and 48 h, the effect of LPS on cell proliferation and gene expression of SDF-1 was investigated by cell counting kit-8 and real-time PCR respectively, while cells without LPS stimulation were considered as negative control.</p><p><b>RESULTS</b>LPS had no significant effect on SCAP proliferation until day 7. RT-PCR assays demonstrated that SCAP expressed SDF-1 mRNA. Different concentrations of LPS significantly promoted the SDF-1 expression in SCAP after 24 h (F = 12.102, P = 0.002) and 48 h (F = 39.054, P < 0.001) exposure, with relative gene expression ratio (experimental/control) increased to 1.4 ± 0.1, 2.2 ± 0.4, 2.3 ± 0.5 in 24 h group and 2.1 ± 0.4, 3.4 ± 0.3, 3.8 ± 0.5 in 48 h group.</p><p><b>CONCLUSIONS</b>Isolated SCAP in cultures have the expression of SDF-1 mRNA. LPS can significantly promote the expression of SDF-1 in SCAP.</p>

Effect of thermal cycling on the composite- composite repair bond strength / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of aging of the composite and the adhesive interface on composite-composite repair bond strength.</p><p><b>METHODS</b>Methacrylate-based composite resin (Clearfil AP-X, composite A) and silorane-based composite resin (Filtek P90, composite B) and their corresponding adhesive, Clearfil SE Bond (adhesive a) and Filtek P90 System Adhesive (adhesive b), were selected in this study. Twenty-four substrates were prepared from composite A or B separately and divided into three groups, each group had 8 substrates: group one, new composites were adhered to the substrates with the use of adhesive a or b, followed by cutting the blocks into sticks; group two, new composites were adhered to the substrates using adhesive a or b, followed by cutting into sticks and thermal cycling; group three, substrates were thermocycled, then polished and adhered new composites using adhesive a or b, followed by cutting into sticks. Each group had 8 combinations of substrate(A, B)-adhesive(a, b)-repair composite (A, B). Fifteen sticks without flaws in each combination of 3 groups were selected utilizing stereomicroscope. The data were analyzed by independent samples t test.</p><p><b>RESULTS</b>In group two, the microtensile strength(MS) of combinations using adhesive a and composite A or B to repair [A-a-A: (45.0 ± 3.2) MPa, B-a-A: (41.7 ± 3.3) MPa, A-a-B: (28.6 ± 3.9) MPa, B-a-B: (47.7 ± 6.6) MPa], and using adhesive b and composite A to repair [A-b-A: (44.2 ± 4.7) MPa, B-b-A: (38.0 ± 3.2) MPa] decreased significantly compared with corresponding combinations in group 1[A-a-A: (70.7 ± 5.5) MPa, B-a-A: (60.3 ± 5.1) MPa, A-a-B: (44.2 ± 1.6) MPa, B-a-B: (54.1 ± 3.2) MPa, A-b-A: (65.6 ± 7.2) MPa, B-b-A: (59.1 ± 4.1) MPa] (P<0.05). However, there was no significant difference between the MS of combinations using adhesive b and composite B to repair in group one and the MS of combinations in group two (P>0.05). The MS of all combinations in group three decreased significantly (P<0.05).</p><p><b>CONCLUSIONS</b>Aging of the composite and the adhesive interface might affect the composite-composite repair bond strength.</p>