Study on biomimetic mineralization of lipopolysaccharide-amine nanopolymersomes/hyaluronic acid polyelectrolyte films on titanium surface / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To explore biomimetic mineralization of polyelectrolyte multilayer films (PEM) of gene-loaded lipopolysaccharide-amine nanopolymersomes/hyaluronic acid self assembled on titanium surface.</p><p><b>METHODS</b>Via lay-by-layer self assembly technology, PEM were constructed on titanium or quartz surface using bone morphogenetic protein-2(BMP-2) plasmid-loaded lipopolysaccharide-amine nanopolymersomes(pLNP) as a polycation, and hyaluronic acid(HA) as a polyanion. The constructed PEM were defined as substrate-pLNP-(HA-pLNP)n, where a successive deposition of HA and pLNP on substrate surface was defined as one assembly cycle, and n was the cycle number. Biomimetic mineralization on surfaces of Ti-pLNP-(HA-pLNP)4(Group A, with outermost layer of pLNP), Ti-pLNP-(HA-pLNP)4.5(Group B, with outermost layer of HA), blank control(polished titanium, Ti) and alkaline-heat treated titanium(Ti-OH) were investigated. The biomimetic mineralization was analyzed by observing the topography under field-emisssion electron microscopy(FE-SEM), characterizing the surface chemical structure and components via X-ray diffractometer(XRD) and X-ray energy disperse spectroscopy(EDS).</p><p><b>RESULTS</b>For experiment groups, XRD analysis showed that the diffraction peak of hydroxyapatite appeared, and its intensity was higher than that for Ti group. FE-SEM images showed that its surface was homogeneously covered by discrete agglomerate of big particles. EDS spectra showed that the percentage of Ca and P were 77.24% and 64.23%, and these were much higher than those in Ti group.</p><p><b>CONCLUSIONS</b>The surface of Ti-pLNP-(HA-pLNP)n is favorable for in vitro biomimetic mineralization.</p>

Selection of shade-matching in dental practice of Shenzhen area / 中华医学美学美容杂志

Objective To survey the shade-matching practice in Shenzhen city so as to strengthen communication between dentists and dental technicians,and to improve the successful rate of shadematching in prosthetic dentistry.Methods Questionnaire surveys were conducted in 251 dentists in some dentistry institutions of Shenzhen during the period from Aug 1st,2008 to Aug 27th,2010,including shade-guide selection,shade-matching technique and communication between dentists and technicians.Questionnaires were collected and statistically analyzed.Results From the analyzed ques tionnaires on shade-taking of 202 dentists,38.6 ％ of dentists evaluated color of restorations with Vitapan 31-Master shade guides; 17.7 ％ preferred Vitapan Classical shade guides,while 41.4 ％ used both.55.9 ％ dentists performed shade-matching in an inappropriate way with Vitapan 3D-Master shade guides.41.6 ％ of them never or rarely cornmunicated with dental technicians about color matc hing problems.Conclusions Shade guides are commonly and widely used by dentists in Shenzhen area.However,and few attentions are paid to a correct way of shade-matching and communications with dental technicians,which might be one of the main causes responsible for color mismatch.

Effect of jaw shape on stresses at implant-bone interface: a three-dimensional finite element analysis / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To study the influence of different shape of lower jaw on stress distribution at bone interface in the mandibular molar region of implant restoration models.</p><p><b>METHODS</b>Six models with different lower jaw shapes were constructed by using three-dimensional finite element method. Implant-bone interface stresses in these models were studied under vertical and lateral loads.</p><p><b>RESULTS</b>No matter in the condition of vertical loading of lateral loading, stress distribution patterns were similar in variant models and differences of stress values were not statistically significant. The maximal differences in Von-Mises stress, compressive stress and tensile stress among the six models were 6.4%, 2.8% and 6.2%respectively.</p><p><b>CONCLUSION</b>It is rational to simplify the lower jaw shape in finite element analysis.</p>