Study on the microstructure of acellular dermal matrix and its biocompatibility with MG63 osteoblast-like cells / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the microstructue of acellular dermal matrix (ADM) and the attachment and proliferation of MG63 osteoblast-like cells on the membrane.</p><p><b>METHODS</b>ADM was experimental group and expanded polytetrafluoroethylene (e-PTFE) membrane was control group. Light microscope and scanning electronic microscope (SEM) were used to observe the microstructure of the two kinds of membrane. MG63 osteoblast-like cells were cultured on the two kinds of membrane and the blank group. The cell viability was checked by cell viability analyzer (CVA) and alkaline phosphatase (ALP) activity was detected by ELISA. SEM was used to observe the adhesion and proliferation of the MG63 osteoblast-like cells on the two kinds of membrane.</p><p><b>RESULTS</b>The ADM was composed of the tissular side and basal lamina side. The tissue side showed scale-shaped structure and the basal lamina side demonstrated many digitations and some pores of folliculus pili. The e-PTFE showed many tiny lined cracks in elliptic structure. The viability of the MG63 osteoblast-like cells on the two kinds of membranes and ALP measurement showed that there was no significant difference between each of the two membrane groups and the blank. The adhesion and proliferation of osteoblast-like cells on the two kinks of membranes were both well.</p><p><b>CONCLUSION</b>ADM has no negative effects on the growth of osteoblast-like cells. ADM is biocompatibile and its microstructure is appropriate for guided bone regeneration materials.</p>

Stress analysis of mandibular second premolar with three different restorations / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the stress intensity and distribution in the dentine of intact endodontically treated mandibular second premolar under three different restorations.</p><p><b>METHODS</b>Four three-dimensional finite element models were constructed by the data of spiral CT: 1) Mandibular second premolar restored directly by full crown: 2) Fill the perforating cavity with resin material and full crown restoration; 3) Cast nickel chromium (NiCr) alloy post core plus full crown restoration; 4) Fiber post and resin core plus full crown restoration. Load was applied on the buccal inclined surface near the top of the buccal cusp and the intensity and distribution of the maximum tensile stress and von Mises stress in the dentine were compared.</p><p><b>RESULTS</b>When the tooth was restored with NiCr alloy post core, an obvious stress concentration area was observed in the dentine next to the top of the post. When the fiber post was used, there was little stress concentration area around the top of the post, and the stress distribution in the dentine was almost the same as the control group. No difference of the intensity and distribution of the stress was found with the control group when no post was used and the perforating cavity was just filled with resin material.</p><p><b>CONCLUSION</b>Compared with cast metal post, fiber post is more suitable for post-core crown restorations. In cases with sufficient coronal tooth substance, post is not absolutely necessary and just filling the perforating cavity with resin material followed by crown restoration can be one of the alternative restorations.</p>

Effects of progressive loading on implants placed into extraction sockets: a preliminary study / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the effects of progressive loading on implants placed into extraction sockets.</p><p><b>METHODS</b>Bilateral 3rd, 4th and 2nd premolar of 4 beagle dogs were extracted and the implants were immediately inserted at 0, 14 and 21 days. The progressive loading procedure was conducted after 24 hours. The vertical bone loss (VBL) and the bone/biomaterials reactions were detected by X-ray and SEM.</p><p><b>RESULTS</b>The VBL in control groups was larger than that for the experimental groups at 14, 21 and 28 days (P<0.05). Scan electron microscopy detected that the mineralization speed of experimental groups was many times as faster as the control groups.</p><p><b>CONCLUSION</b>Progressive loading of implants placed into extraction sockets can be performed without disturbing the osseointegration process. The potential of new bone formation in the extraction sockets and the physical strains can congenerously promote osseointegration.</p>