Objective:To evaluate the effects of Er,Cr:YSGG laser combined with NaF treatment on the acid resistance of human dental hard tissue.Methods:The enamel or dentin samples were randomly divided into four groups and prepared by different methods as follows: ①without treatment(control group),②laser irradiation(Laser group),③ treated with 20 g/L NaF solution(NaF group),④laser irradiation+ NaF solution treatment(Laser and NaF group).The samples of each group were respectively demineralized in 0.1 mol/L of lactic acid for 24 h and the calcium ion in the demineralization solution in each group was measured by atomic absorption spectrophotometry.The fluoride on the surface of the samples was examined by SED-X and the ultrastructure was investigated by SEM.Results:The concentrations of Ca~(2+) dissolved from the enamel or dentin samples in NaF,laser and NaF and laser groups were significantly lower than that in the control group(P(0.05)).Only in the NaF group,the F peak appeared.SEM observation showed the lased surface showed various patterns of microirregulation with a scaly appearance,the openings of dentinal tubules were visible,but no melting or carbonization;there were lot of particles attached to the surface of NaF treated samples;the ultrastructure of the NaF and laser-treated sample surfaces was similar to that of the laser treated.Conclusion:The combined use of laser and NaF dose not have synergetic effects on acid resistance of human dental hard tissue.

Objective To study the pathology of primary neuroectodermal tumor (PNET),and its diagnostic standards and prognostic factors.Methods Expression of CD99,FLI-1,Syn,NSE,S-100,NF,and Vim was detected in PNET tissues stained with HE and immmunohistochemistry (En Vision method).Survival rate of 33 PNET patients with complete clinical information was analyzed with COX regression analysis method.Results The positive expression rate of CD99,FLI-1,Vim,Syn,NSE and s-100 was 88.57%,51.43%,91.42%,48.57%,45.71%,and 22.86%,respectively.The sensitivity of combined CD99 and FLI-1 was 100%.However,NF was not expressed in all PNET tissues.When other factors were unchanged,no difference was found in the effect of age on the survival rate of patients.However,a significant difference was observed in the effect of PNET site and its treatment modalities on the survival rate of patients (P

BACKGROUND:The residual alveolar ridge in edentulous patients with osteoporosis always presents with a poor shape,which increases the difficulty in complete denture restoration.Until now,there are no predictors for residual alveolar ridge resorption or guidelines on the frequency of denture relines.OBJECTIVE:To investigate the correlation between the frequency of complete denture relines and serum bone turnover markers,osteocalcin (OC) and cross-linked carboxy-terminal telopeptide of type Ⅰ collagen (CTX),in elderly edentulous patients with osteoporosis,in order to provide reference for complete denture repair.METHODS:According to inclusion criteria,50 elderly edentulous patients with osteoporosis who had complete dentures were recruited in the study randomly.The frequency of complete denture relines was surveyed by related questionnaire and medical record,and the serum OC and CTX levels were detected by electrochemiluminescence immunoassay.Related data were analyzed statistically via Pearson correlation analysis.RESULTS AND CONCLUSION:It showed a strong positive correlation between the frequency of complete denture relines and the serum OC level (r=0.517,P ＜ 0.01).No significant correlation between relines frequency and the serum CTX level was observed (r=0.278,P=0.051 ＞ 0.05),but it showed a similar tendency between them.These findings indicate that to detect the levels of serum bone turnover markers may be conducive to evaluating curative effect of complete dentures in elderly edentulous patients with osteoporosis as well as to making subsequent diagnostic and therapeutic strategies.

OBJECTIVEThe purpose of this study was to evaluate the morphological changes of Er, Cr: YSGG laser irradiated dental hard tissues by scanning electron microscopy (SEM).

METHODS12 freshly extracted premolars were treated with fissure bur, Er, Cr: YSGG laser at 4 watt, Er, Cr: YSGG laser at 6 watt, respectively, and then bisected transversally and longitudinally. The tooth slice were prepared with conventional methods and observed by SEM.

RESULTSCompared with fissure bur, laser treatment resulted in a rather scaly and rough surface. The sections were free of smear layer, with open dentinal tubules. No carbonization and thermal damages were observed. The laser at 6 watt appeared rougher than at 4 watt, occasionally caused micro-cracks.

CONCLUSIONThe utilizing of Er, Cr: YSGG laser can contribute to enhance the bond strength between restorative materials and dental hard tissues. It suggests that higher energy could be applied in cutting enamel, whereas the lower energy in dentin.

Dental Cavity Preparation ; instrumentation ; methods ; Dental Enamel ; radiation effects ; ultrastructure ; Dental High-Speed Equipment ; Dentin ; radiation effects ; ultrastructure ; Hardness ; Humans ; In Vitro Techniques ; Lasers ; Microscopy, Electron, Scanning ; Tooth ; radiation effects ; ultrastructure