Effect of KH2PO4 on the odonto- and osteogenic differentiation potential of human stem cells from apical papillae / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To determine the effects of KH2PO4 on the odonto- and osteogenic differentiation potential of human stem cells from apical papillae (SCAP) in vitro.</p><p><b>METHODS</b>SCAP were isolated and cultured respectively in alpha minimum essential medium (α-MEM) or α-MEM containing 1.8 mmol/L KH2PO4. Alkaline phosphatase (ALP) activity, alizarin red staining, real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting were used to examine the odonto and osteogenic potential of SCAP in the two media.</p><p><b>RESULTS</b>SCAP cultured in α-MEM containing 1.8 mmol/L KH2PO4 exhibited a higher ALP activity [(0.370 ± 0.013) Sigma unit×min(-1)×mg(-1)] at day 3 than control group [(0.285 ± 0.008) Sigma unit×min(-1)×mg(-1)] and KH2PO4-treated SCAP formed more calcified nodules at day 5 [(0.539 ± 0.007) µg/g] and day 7 [(1.617 ± 0.042) µg/g] than those in normal medium [(0.138 ± 0.037) µg/g, P < 0.01]. The expression of odonto- and osteogenic markers were significantly up-regulated after the stimulation of KH2PO4 at day 3 and 7 respectively, as compared with control group.</p><p><b>CONCLUSIONS</b>1.8 mmol/L KH2PO4 can promote the odonto and osteogenic differentiation potential of human SCAP.</p>

Nonlinear finite element analysis of three implant- abutment interface designs / 国际口腔科学杂志·英文版

The objective of this study was to investigate the mechanical characteristics of implant-abutment interface design in a dental , using nonlinear finite element analysis (FEA) method. This finite element simulation study was applied on three commonly used commercial dental implant systems: model I, the reduced-diameter 3i implant system (West Palm Beach, FL, USA) with a hex and a 12-point double internal hexagonal connection; model II, the Semados implant system (Bego, Bremen, Germany) with combination of a conical (450 taper) and internal hexagonal connection; and model III, the Brinemark implant system (Nobel Biocare, Gothenburg,Sweden) with external hexagonal connection. In simulation, a force of 170 N with 45" oblique to the longitudinal axis of the implant was loaded to the top surface of the abutment. It has been found from the strength and stiffness analysis that the 3i implant system has the lowest maximum von Mises stress, principal stress and displacement while the Br Bnemark implant system has the highest. It was concluded from our preliminary study using nonlinear FEA that the reduced-diameter 3i implant system with a hex and a 12-point double internal hexagonal connection had a better stress distribution, and produced a smaller displacement than the other two implant systems.

Bilateral maxillary fused second and third molars: a rare occurrence / 国际口腔科学杂志·英文版

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months.

Detecting MTHFR gene mutation with a new approach: molecular beacons / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect the methylenetetrahydrofolate reductase(MTHFR) gene C677T mutation with molecular beacon technique and assess the revant applicability.</p><p><b>METHODS</b>A total of 228 samples were analyzed using molecular beacons which are oligonucleotide probes to become fluorescent upon hybridization. Wild-type molecular beacon and mutant beacon were designed to detect the genotypes of MTHFR gene.</p><p><b>RESULTS</b>Analysis of the 228 samples indicated that there were three genotypes including 41 homozygous mutants, 113 heterozygous individuals and 74 wild-type individuals. Every sample was identified clearly.</p><p><b>CONCLUSION</b>The present method, a closed-tube PCR/hybridization assay, is a simple, high-throughput and fast procedure that is fully automated for detecting gene mutation.</p>