Gelfoam haemostatic agent with or without autologous bone marrow-derived stem cells for the regeneration of critical-size mandibular defects in the rabbit

This study evaluated the effect of Gelfoam sponge with and without autologous bone marrow-derived stem cells (BMSCs) on bone regeneration in critical-size mandibular defects. The study involved 56 New Zealand rabbits assigned to four groups (14 in each). The osseous defects in group I were irrigated with normal saline, those in group II were grafted with autogenous tibial bone, and those in group III were filled with Gelfoam sponge. Group IV defects were treated as for group III, but the interface between the Gelfoam sponge and bone surface was injected with BMSCs. At the end of 4 weeks, seven rabbits in each group were euthanized; the remaining animals were euthanized at the end of the experiment, at 8 weeks postoperative. The percentage area of newly formed bone was significantly higher in group IV at week 4 (0.030 ± 0.01%) and week 8 (0.060 ± 0.03%) than in group I (0.01 ± 0.00% and 0.02 ± 0.00%, respectively) and group III (0.08 ± 0.01% and 0.015 ± 0.02%, respectively), but was lower than that in group II (0.038 ± 0.02% and 0.082 ± 0.01%, respectively). Thus, the combination of Gelfoam and autologous BMSCs promoted the regeneration of mandibular critical-size defects better than the use of Gelfoam alone. However, the amount of newly generated bone was lower than in defects grafted with autogenous bone.     

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??Objective    To evaluate the biomechanical influence of the relationship between implant tip and sinus ?oor cortical bone on posterior maxilla implantation by means of 3-dimensional??3-D??finite element??FE??analysis. Methods        Six 3-D FE models ??M1 to M6?? of standard implants and posterior maxillary region were constructed using CAD software. The thickness of both crestal cortical bone and sinus floor cortical bone were 1mm??according to different heights of the alveolar bone??the relationship between implant tip and sinus floor cortical bone was as follows. M1??the implant tip just broke through sinus cortical bone??the upper surface of sinus cortical bone and the apical surface of the implant were at the same level????M2??the implant tip broke through half the thickness of sinus ?oor cortical bone??M3??the implant tip just made contact with the lower surface of sinus ?oor cortical bone??for the remaining models??the implant tips were 1mm??2mm and 3mm apart from sinus floor??respectively. An inclined force of 129N was applied under immediate loading and conventional loading. The maximum von Mises stress??stress distribution??implant displacement and resonance frequencies were calculated using CAD software. Results    Except the M1 under immediate loading??the maximum von Mises stress of all models were concentrated on the surface of the crestal cortical bone around the implant neck. When the implant tip broke into or through sinus floor cortical bone??the maximum von Mises stress of crestal cortical bone reduced while that of sinus cortical bone increased??and the occlusional resonance frequencies of implants increased significantly while horizontal frequencies decreased??whether under immediate loading or conventional loading. Under immediate laoding??the maximum displacement of implant??especially the maximum displacement of the implant tip??was lower than the other models when the implant tip broke into or through the sinus cortical bone. However??the maximum displacements of both implant neck and tip were  hardly affected by the association between implant tip or sinus floor cortical bone under conventional loading. Conclusion    The association between implant tip and sinus floor cortical bone has effects both on stress distribution of the bone tissues around implant and on the maximum displacement and resonance frequencies of implants. Making the implant tip break into or through the sinus floor cortical bone??bi-cortical anchorage??is beneficial to improve the stress distribution and reduce the maximum displacement of implant??increasing the stability of the implant??especially under immediate loading.     

PLGA/鱼皮胶原共轭静电纺丝膜生物相容性分析

目的： 对一种新型聚乳酸-羟基乙酸（polylactic acid-glycolic acid，PLGA）/鱼皮胶原共轭静电纺丝膜的生物相容性进行分析。方法： 以PLGA和医用级鱼皮Ⅰ型胶原为原材料，通过共轭静电纺丝技术制备出高取向性的纳米纤维膜，然后分别以小鼠成纤维细胞L929为研究模型，初步评价其细胞、组织相容性，为其用于种植骨组织再生（guided bone regeneration，GBR）提供实验依据。结果： 纤维细胞在纤维膜表面黏附生长良好，有大量细胞伸出伪足，沿着纤维的取向进行铺展排列。结论： PLGA/鱼皮胶原共轭静电纺丝膜有利于成纤维细胞生长，可望用于种植骨组织再生。     

Turned versus anodised dental implants: a meta‐analysis

The aim of this meta‐analysis was to test the null hypothesis of no difference in the implant failure rates, marginal bone loss (MBL)and post‐operative infection for patients being rehabilitated by turned versus anodised‐surface implants, against the alternative hypothesis of a difference. An electronic search without time or language restrictions was undertaken in November 2015. Eligibility criteria included clinical human studies, either randomised or not. Thirty‐eight publications were included. The results suggest a risk ratio of 2·82 (95% CI 1·95–4·06, P < 0·00001) for failure of turned implants, when compared to anodised‐surface implants. Sensitivity analyses showed similar results when only the studies inserting implants in maxillae or mandibles were pooled. There were no statistically significant effects of turned implants on the MBL (mean difference‐MD 0·02, 95%CI ?0·16–0·20; P = 0·82) in comparison to anodised implants. The results of a meta‐regression considering the follow‐up period as a covariate suggested an increase of the MD with the increase in the follow‐up time (MD increase 0·012 mm year^?1), however, without a statistical significance (P = 0·813). Due to lack of satisfactory information, meta‐analysis for the outcome ‘post‐operative infection’ was not performed. The results have to be interpreted with caution due to the presence of several confounding factors in the included studies.     

Bone metabolism induced by denture insertion in positron emission tomography

18F‐fluoride positron emission tomogra‐phy (PET) can identify subtle functional variation prior to the major structural change detectable by X‐ray. This study aims to investigate the mechanobiological bone reaction around the abutment tooth and in the residual ridge, induced by insertion of removable partial denture (RPD) within two different groups of patients: patients without denture experience (Group 1) and patients with denture experience before (Group 2), using 18F‐fluoride PET imaging technique. 18F‐fluoride PET/computerised tomography (CT) scan was performed to examine the bone metabolic change in mandible before and after the RPD treatment. Region of interests (ROIs) were placed in alveolar bone around abutment tooth and in residual bone beneath the RPD. Standardised uptake value (SUV), reflecting the accumulation of 18F‐fluoride, was measured for each ROI. In all subjects of Group 1, SUVs after insertion were higher than before in both alveolar bone and residual bone, while there was less significant change in SUV in subjects of Group 2. This study demonstrated using longitudinal 18F‐fluoride PET scans to effectively examine the bone metabolic change in mandible induced by occlusal loading after RPD insertion. Using this technique, within the six subjects in this study, it was shown that bone metabolism around abutment tooth and residual ridge increased after RPD insertion in case of first‐time denture user, while there was no big change in the patient with experience of denture before. This study revealed the effectiveness of applying PET to evaluate bone metabolic activity as mechanobiolo‐gical reaction.     

空心环钻髂骨取骨的应用

正2011年12月~2014年12月,笔者采用空心环钻髂骨取骨的手术方法,操作简便,可满足临床中小骨量要求,报道如下。1材料与方法1.1病例资料本组61例,男34例,女27例,年龄23~62岁。空心环钻(外径1.0 cm,内径0.8 cm,长度15 cm)于髂骨钻取松质骨,均用于四肢骨缺损:新鲜骨折48例,骨折愈合不良或不愈合