BACKGROUND:Sodium alginate and chitosan are the polycation and polyanion natural polymer materials respectively, and they can be crosslinking agents complementing each other to form composite gel and avoid the cytotoxicity resulting from some common crosslinking agents .
OBJECTIVE:To prepare the chitosan-sodium alginate composite gel and evaluate its cytotoxicity in vitro. METHODS:Chitosan was dissolved in 0.25 mol/L acetic acid to make a 30 g/L mass concentration solution, and 0.1 mol/L NaOH solution was added to neutralize its acidity. Neutralization of the chitosan solutions leads to the formation of a precipitate in ultrasmal particles. Then the chitosan and 3%sodium alginate solution in deionized water were mixed in 1:1 volume ratio by high frequency oscil ating to produce composite gel. The composite gel were detected by scanning electron microscopy and Fourier transform infrared spectrometry after freeze-drying. The 24-hour and 72-hour leaching solutions of composite gel, 24-hour and 72-hour leaching solutions of polyethylene and phenol solution were added to the L-929 cells’ culture medium respectively in order to evaluate the cytotoxicity of composite gel in vitro.
RESULTS AND CONCLUSION:The results of Fourier transform infrared spectrometry showed the variation of characteristic peak values of composite gel which were different from sodium alginate and chitosan;and under scanning electron microscope, a spatial network structure formed with abundant intervals. Result of the cytotoxicity valuation was qualified for the chitosan-sodium alginate composite gel. These findings indicate that the chitosan-sodium alginate composite gel can be used as tissue engineering scaffold materials.

OBJECTIVETo explore the efficacy of optical coherence tomography (OCT) in imaging and quantitatively evaluating early enamel caries and provide experimental evidence for the clinical diagnosis of early caries.

METHODSThe smooth surface of bovine teeth showing early artificial caries and demineralization changes was scanned by an all fiber-based OCT for images and optical profiles, which were compared with images from a polarized light microscope (PLM) and mineral loss from an atomic absorption spectrometer. Data were analyzed by paired-sample t-test and Pearson correlation analysis using SPSS software.

RESULTSThe images of enamel with early caries and demineralization from OCT coincided with those from PLM. The integrated reflectivity loss in the early caries group was significantly lower than that in the demineralized group (P < 0.05), whereas no significant difference in demineralized depth was found between the two groups (P > 0.05). A linear correlation was observed between integrated reflectivity loss and mineral loss (P < 0.05).

CONCLUSIONOCT can be used to nondestructively and accurately image early caries and quantify lesion extent and degree, suggesting the extensive use of this approach in the clinical diagnosis of early caries.

Animals ; Cattle ; Dental Caries ; Dental Enamel ; Tomography, Optical Coherence ; Tooth Demineralization

Objective Quantitative analysis of optical coherence tomography (OCT) images of naturally occurred early enamel caries was performed to find quantitative parameter indicator for detecting early caries by OCT.Methods Three human premolars with enamel natural caries in D0,D1,and D2 stages were selected respectively and scanned by OCT.The ratios of the average gray value of the caries region (object region) and sound region (background region),namely,the object-background contrast (OBC) were calculated in OCT images and selected as the quantitative parameters to analyze the OBC trend of different degree of enamel caries.Results Within the fixed depth,the OBC value showed a trend of first increase and then decrease with the severity of dental caries,indicating that OBC value increased with the severity of dental caries from normal to D1 stage,and then decreased from D1 to D2 stage.Conclusion The OBC value can be used as a new quantitative indicator for OCT to estimate the severity of naturally occurred early caries.

2 mmx3 mm experimental windows were prepared in adamant slippery surfaces of 7 fresh uprooted permanent teeth. The teeth surfaces in the windows area were demineralized to create artificial caries mould of early stage by aciding the experimental teeth surfaces of 0, 12, 24, 48, 72, 96, 120 hours with demineralized liquid (pH 4.5) in vitro. The demineralized changes on the experimental teeth surfaces were detected by dental Optical Coherence Tomography (OCT) system, which were newly developed by our research group recently, and the detecting results were compared with clinical digital photomicrography and scanning electron microscopy on the same tooth sample, to checkout the efficacy and feasibility of dental OCT for early quantification detecting of artificial enamel demineralization in vitro. The dental OCT system can safelydetect early enamel demineralization of micron level and noninvasively obtain fine resolution quantification information both in surfaces view and sectional view; OCT could accurately detect surface demineralization changes on the experimental windows of artificial dental caries as early as after 12 hours aciding treatment, earlier than the visual inspection and clinical digital photomicrography. OCT could obtain both superficial view and sectional view of quantificational demineralization in early enamel caries homeochronously, and had high correlation to the results of ultramicromorphological changes detected by scanning electron microscopy. Dental OCT system developed by our group could accurately detect early artificial dental caries atraumaticly with high sensitivity and safety. Moreover, it can obtain quantification data in micron level without damaging the experimental teeth samples.

Objective To explore the clinical efficacy and safety of modified PPH combined with partial internal anal sphincterotomy in the treatment of circular mixed hemorrhoids.Methods Patients with annular mixed hemorrhoids were divided into two groups by a completely randomized controlled method.54 patients in the experimental group were treated with modified PPH combined with partial internal anal sphincterotomy,while 51 patients in the control group were treated with conventional PPH.The postoperative indicators,perioperative and long-term complication rates of the two groups were compared,and the clinical efficacy and safety were observed.Results The operation time in the experimental group was(48.35±4.37)minutes,which was higher than that in the control group(36.42 ±6.21)minutes(P＜0.05).The incidence of postoperative anastomotic stenosis in the experimental group was 1.9％,lower than 15.6％ in the control group(P＜0.05).Anal pain,urinary retention,first defecation time,long-term anal distention,the experimental group was significantly better than the control group,the difference was statistically significant(P＜0.05);The hospitalization time in the experimental group(4.8±0.62)days was not significantly different from that in the control group(5.1±0.54)days(P＞0.05).The amount of intraoperative bleeding and anastomotic bleeding in the experimental group[(17.28±2.22)ml,3.7％]were not significantly different from those in the control group[(16.75± 2.13)ml,3.9％](P＞0.05).Conclusion Compared with conventional PPH,the modified PPH combined with partial internal anal sphincterotomy slightly increases the operation time,but does not increase the risk of anastomotic bleeding,the incidence of rectal fistula,the amount of surgical bleeding,and the length of hospital stay.It can significantly improve postoperative anal pain,urinary retention,long-term distention symptoms,shorten the time of first defecation,ease the difficulty of defecation,and significantly reduce postoperative anastomotic stenosis,The long-term efficacy and safety are good.