The influence of three barrier membranes on modeling and incorporation of autologous onlay bone grafts in rats. An evaluation by transversal microradiography

Objectives

To determine whether covering an autologous bone grafts with three different barrier membranes prevents graft resorption, and to compare these membranes to each other.

Design

In 192 rats a standardised 4.0 mm diameter bone graft was harvested from the right mandibular angle and transplanted to the left. Membranes used to cover the grafts were a new poly(dl-lactide-?-caprolactone) membrane, a collagen and expanded polytetrafluoroethylene membrane. The controls were left uncovered. Graft resorption and incorporation were measured with transversal microradiography (TMR) in the four groups at 2, 4 and 12 weeks. Data were analysed using multiple regression analyses.

Results

Overall, there were no differences in modeling with resorption between the four groups. ePTFE at 12 weeks showed a lower mineralization ratio and graft height of the graft as compared to the other groups. The mean graft incorporation was progressive and nearly identical from 2 to 12 weeks in all groups.

Conclusions

Membranes have an equal effect on bone graft modeling and resorption as found in non-covered controls. Therefore, the indication to use a barrier membrane to prevent bone modeling with resorption and enhance incorporation of autologous onlay bone grafts is disputable.     

Quantification of the mandibular defect healing by micro-CT morphometric analysis in rats

Purpose

The goal of this study was the evaluation of the bone tissue structural characteristics over the time course of mandibular defect healing using micro-CT technique, as well as determination of the inter-relationships between different micro-CT parameters used for assessment of the bone regeneration process and the patterns of their dynamic changes.

Effects of sintered apatite on bone regeneration in rabbits

Apatite is considered to be effective for bone regeneration when it contains calcium carbonate and β-TCP. In the present study, we made 3 different apatite preparations, hydroxyapatite, hydroxyapatite containing calcium carbonate, and hydroxyapatite containing β-TCP, using spark plasma sintering and compared their abilities for osteoinduction. For elucidation of bone regeneration, evaluations are generally made after euthanasia of experimental animals. However, the present R_mCT^® procedure allowed such evaluations while the animals were alive. Our results showed that sintered HAP containing β-TCP was more effective for guided bone regeneration than the other test materials.     

A collagen membrane containing osteogenic protein-1 facilitates bone regeneration in a rat mandibular bone defect

ObjectivesOsteogenic protein-1 (OP-1) has shown osteoinductive activities and is useful for clinical treatments, including bone regeneration. Regenerative procedures using a bioabsorbable collagen membrane (BCM) are well established in periodontal and implant dentistry. We evaluated the subsequent effects of the BCM in combination with OP-1 on bone regeneration in a rat mandibular circular critical-sized bone defect in vivo.DesignWe used 8 rats that received surgery in both sides of the mandible, and created the total 16 defects which were divided into 4 groups: Group 1; no treatment, as a control, Group 2; BCM alone, Group 3; BCM containing low dose 0.5 μg of OP-1 (L-OP-1), and Group 4; BCM containing high dose 2.0 μg of OP-1 (H-OP-1). Newly formed bone was evaluated by micro computed tomography (micro-CT) and histological analyses at 8 weeks postoperatively. In quantitative and qualitative micro-CT analyses of the volume of new bone formation, bone density, and percentage of new bone area was evaluated.ResultsBCM with rhOP-1 significantly increased and accelerated bone volume, bone mineral density, and percentage of new bone area compared to control and BCM alone at 8 weeks after surgery; these enhancements in bone regeneration in the OP-1-treated groups were dose-dependent.ConclusionsOP-1 delivered with a BCM may have effective osteoinductive potency and be a good combination for bone regeneration. The use of such a combination device for osteogenesis may result in safer and more predictable bone regenerative outcomes in the future.     

The local administration of parathyroid hormone encourages the healing of bone defects in the rat calvaria: Micro-computed tomography,histological and histomorphometric evaluation

ObjectiveTo evaluate the effect of a single-dose local administration of PTH on bone healing in rat calvarial bone defects by means of micro-computed tomography, histological and histomorphometric analysis.DesignCritical-size cranial osteotomy defects were created in 42 male rats. The animals were randomly divided into 3 groups. In the C Group, the bone defect was only filled with a blood clot. In the S Group, it was filled with a collagen sponge and covered with bovine cortical membrane. In the PTH Group, the defect was filled with a collagen sponge soaked with PTH and covered with bovine cortical membrane. The groups were further split in two for euthanasia 15 and 60 days post-surgery. Data was statistically analyzed with t-tests for independent samples or the nonparametric Mann-Whitney test when applicable. Intragroup comparisons were analyzed with paired t-tests (p < 0.05).ResultsMicro-CT analysis results did not demonstrate statistically significant intergroup differences. At 15 days post-surgery, the histomorphometric analysis showed that the PTH Group exhibited a significantly higher percentage of bone formation compared with the S Group. At 60 days post-surgery, a higher percentage of new bone was observed in the PTH group.ConclusionThe results suggest that the local administration of PTH encouraged the bone healing in critical-size calvarial defects in rats.     

Effects of bone regeneration materials and tooth movement timing on canine experimental orthodontic treatment

Objectives:To evaluate the effects of bone regeneration materials and orthodontic tooth movement (OTM) timing on tooth movement through alveolar bone defects treated with guided bone regeneration (GBR) utilizing xenografts (Bio-Oss) and alloplast (β-TCP).Materials and Methods:Twenty-four standard alveolar bone defects in six male beagle dogs were treated by GBR using either Bio-Oss or β-TCP (experimental), whereas the control defects were left empty. The defects were further grouped into early or late subgroups, depending on OTM timing after GBR (ie 1 month or 2 months, respectively). Rates of OTM were measured intraorally, while computed tomography scan images were used to assess bone density, alveolar bone height, second premolar displacement, and tipping tendency.Results:Generally, the Bio-Oss early and Bio-Oss late subgroups recorded the lowest amount of tooth movement compared with other modes of GBRs assessed. Before OTM, the control group registered significantly lower bone height compared with the Bio-Oss and β-TCP groups (P < .01). The control group was inferior on bone density and bone height compared with Bio-Oss and β-TCP.Conclusions:The Bio-Oss group had favorable radiologic features (higher alveolar bone level and bone density with less premolar tipping) but showed slower OTM than the control group. The late OTM subgroup had favorable radiologic features and showed faster tooth movement than the early OTM in the β -TCP group.     

钛膜引导骨生长保持牙槽骨骨量的临床研究

目的评价钛膜在拔牙后引导骨生长保持牙槽骨骨量的临床效果，并探讨其应用技巧。方法选取62例只拔除1颗前牙的病例，随机分为3组，第1组（21例）为对照组，拔牙后3～4个月回院接受种植牙手术，第2组（20例）为钛膜组，拔牙后牙槽窝经过修整，放置稍大于牙槽窝的纯钛膜并将周围组织拉拢缝合。5～6个月回院接受种植牙手术或钛膜取出手术。第3组（21例）为钛膜加人工骨组．拔牙后牙槽窝即刻填入人工骨并放置稍大于牙槽窝的纯钛膜并缝合．5～6个月回院接受种植牙手术或钛膜取出手术。在曲面断层片上测量牙槽骨高度的变化。以上各组分别于拔牙后1、2、3及6个月后进行牙槽骨密度的测量。结果在拔牙后5～6个月时，牙槽骨平均退缩率分别为（26．42±0．89）％，（14．71±0．92）％，（7．434±0．76）％。第1、2组间差异具有统计学意义（P〈0．01）；在术后1～2个月时．第2、3组牙槽窝骨密度均高于第1组（P〈0．01）。结论钛膜可以有效保持拔牙后牙槽骨骨量．部分病例有拔牙创未能关闭及早期裂开现象，适当处理，未明显影响新生骨形成。     

Vivosorb, Bio-Gide, and Gore-Tex as barrier membranes in rat mandibular defects: an evaluation by microradiography and micro-CT

Objectives: The objectives of this study were to determine whether a new degradable synthetic barrier membrane (Vivosorb^®) composed of poly(dl ‐lactide‐?‐caprolactone) (PDLLCL) can be useful in implant dentistry and to compare it with collagen and expanded polytetrafluoroethylene (ePTFE) membranes. Material and methods: In 192 male Sprague–Dawley rats, a standardized 5 mm circular defect was created through the right angle of the mandible. New bone formation was evaluated by post‐mortem microradiography and micro‐CT (μCT) imaging. Four groups (control, PDLLCL, collagen, ePTFE) were evaluated at three time intervals (2, 4, and 12 weeks). In the membrane groups the defects were covered; in the control group the defects were left uncovered. Data were analysed using a multiple regression model. Results: New bone formation could be detected by post‐mortem microradiography in 130 samples and by μCT imaging in 112 samples. Bone formation was progressive in 12 weeks, when the mandibular defect was covered with a membrane. Overall, more bone formation was observed underneath the collagen and ePTFE membranes than the PDLLCL membranes. Conclusions: In contrast to uncovered mandibular defects, substantial bone healing was observed in defects covered with a PDLLCL membrane. However, bone formation in PDLLCL‐covered defects tended to be less than in the defects covered with collagen or ePTFE. The high variation in the PDLLCL samples at 12 weeks may be caused by the moderate adherence of this membrane to bone compared with collagen. These results indicate that further study is needed to optimize the properties of PDLLCL membranes.     

A prospective histomorphometric and cephalometric comparison of bovine bone substitute and autogenous bone grafting in Le Fort I osteotomies

Purpose

The aim of the present study was the histomorphometric and cephalometric comparison of autogenous bone grafting of the anterior iliac crest and the application of bovine bone substitute concerning new bone formation and postoperative stability in patients undergoing orthognathic Le Fort I osteotomy.

Analysis of calvarial bone defects in rats using microcomputed tomography: potential for a novel composite material and a new quantitative measurement

Reconstruction of craniomaxillofacial defects is a challenge for surgeons and has psychological and functional burdens for patients. Undoubtedly, there is a need for improved biomaterials and techniques for craniomaxillofacial reconstruction.     

基于micro-CT的下颌牙龈癌颌骨侵犯的影像学评估及分析

目的： 对下颌牙龈癌颌骨侵犯进行影像学评估及分析,为进一步优化手术方案及术后治疗提供影像学依据。方法： 选择60例下颌牙龈癌手术患者,分析术前曲面体层片、平扫和增强CT,并对其中符合条件的30例手术标本进行micro-CT三维重建,分析骨密度、骨小梁厚度、骨小梁分离度等相关参数。采用SPSS 22.0软件包对数据进行统计学分析。结果： 常规影像学检查,曲面体层片、平扫及增强CT均有不足,micro-CT三维重建可以准确区分骨松质及骨皮质,评估下颌骨侵犯的范围及程度,相应的数据参数分析癌边缘及癌中心与正常下颌骨组织的皮质骨骨密度显著降低（P<0.05）,骨小梁厚度显著变薄（P<0.05）,松质骨骨密度显著降低（P<0.05）。癌中心与正常下颌骨组织骨小梁分离度增加（P<0.05）。结论： 目前对于下颌牙龈癌的手术方案还存在争议,进一步提高CT检查精度,可能会为制定下颌牙龈癌手术方案提供更精确的指导。     

Age- and sex-related changes of mandibular condylar cartilage and subchondral bone: A histomorphometric and micro-CT study in rats

Objective

To quantify the age- and sex-related changes in the rat condylar cartilage and subchondral bone.

Methods

SD rats were obtained at the ages of 2, 3, 4, 5, 6 and 7 months. For each sex, the temporomandibular joints tissue blocks from four rats were subjected to histological assessment of cartilage thickness and subchondral bone architecture; for the remaining three rats, the mandibular condyles were delivered for gross measurement and evaluation of the mineralization and architecture properties of the subchondral bone by means of micro-CT.

Results

Rapid decrease of cartilage thickness but increase of subchondral bone density occurred respectively from 2 to 3 and 3 to 4 months old in female and 2 to 4 and 3 to 5 months old in male (P < 0.05), whereas rapid changes of subchondral bone architecture occurred from 3 to 4 months old in both sexes (P < 0.05). The significant enlargement of condyle size occurred at 4 or 5 months old in female but at 5 or 6 months in male (P < 0.05).

Conclusion

This study demonstrated that the rapid developmental changes of rat condylar cartilage and subchondral bone primarily occurred before 4 months of age, resulting in thinner cartilage but larger and thicker subchondral bone, and they were followed by rapid growth in condylar size. Sex differences were identified that the endochondral ossification of fibrocartilage and formation of subchondral bone were faster in female than in male rats, leading to the earlier enlargement of condyle in female than in male.     

Effect of dietary calcium deficiency and altered diet hardness on the jawbone growth: A micro-CT and bone histomorphometric study in rats

ObjectivesWe examined the effects of a low-calcium diet and altered diet hardness on bone architecture and metabolism in the maxilla and mandible.Materials and methodsMale rats (n = 48, 3 weeks old) were divided into six groups. In total, 24 rats were given a normal-calcium diet and the others were given a low-calcium diet. Each group was then divided into three subgroups, which were fed a ‘hard̕ diet for 8 weeks, a ‘soft̕ die for 8 weeks, or switched from the soft diet after 4 weeks to the hard diet for 4 weeks. The bone architecture was analyzed using cephalometry and micro-computed tomography, in addition, the bone metabolism was analyzed using serum bone markers and bone histomorphometry in the maxilla and mandible. Moreover, the bone formation patterns were evaluated using histopathologically in the midpalatal suture.ResultsThe low-calcium diet affected bone architecture by increasing bone turnover and the soft diet affected bone architecture mainly by increasing bone resorption. The soft diet changed the chondrocyte cell layers into fibrous connective tissues in the midpalatal suture. At 4 weeks after the return to a hard diet from a soft diet, recovery of the deterioration in bone architectures was seen in the maxilla and mandible.ConclusionsWe demonstrated that mastication with a hard diet is effective for recovering the collapsed equilibrium of jaw bone turnover and the deteriorating jaw bone architectures due to the poor masticatory function during the growing period.     

低分子壳寡糖对LPS诱导的小鼠颅骨吸收的抑制作用

目的: 研究低分子量壳寡糖（low-molecular chitosan oligosaccharide,LMCOS）对脂多糖（lipopolysaccharides,LPS）诱导的小鼠颅骨吸收模型的影响,评估其在小鼠颅骨吸收过程中的抑制作用。 方法: 将6周龄C57/BL6雄性小鼠随机分为 5组,即磷酸缓冲液（PBS）组、LPS组、LPS+0.005% LMCOS组、LPS+0.05% LMCOS组和LPS+0.5% LMCOS组;每组5只,LPS的刺激量为10 mg/kg。小鼠浅麻醉后,于颅盖骨皮下注射相应试剂,每只注射300 μL。每周小鼠头部皮下组织和颅骨骨膜之间注射试剂3次,2周后处死,取出颅盖骨进行Micro-CT扫描、H-E染色、TRAP 染色。采用SPSS21.0软件包对数据进行单因素方差分析,观察骨破坏面积、破骨细胞的形成等骨缺损表现。 结果: Micro-CT扫描、H-E染色、TRAP 染色发现,与PBS组相比,LPS组小鼠颅骨表面的骨破坏十分明显;加入不同浓度的LMCOS后,颅骨骨破坏面积及破骨细胞数目随LMCOS浓度的升高而不断减少。 结论: LMCOS具有抑制LPS诱导的小鼠颅骨骨吸收的作用,提示LMCOS对骨破坏性疾病可能具有一定的治疗作用。     

Bio-Oss骨代用品同引导骨再生膜联合应用效果的观察

目的 通过组织学观察Bio-Oss作为骨移植材料同引导骨再生膜技术联合应用治疗牙槽骨局部骨缺损及种植体周围骨缺损的临床效果。方法 从6例牙槽骨局部缺损患者的6处骨再生区取少量骨组织，采取Donath硬组织切片磨片技术行组织学观察。结果 组织学显示浅红色新生骨同淡黄色的Bio-Oss颗粒区别明显，Bio-Oss颗粒表面有新骨形成，并与之紧密结合。未见纤维结缔组织长入包裹Bio-Oss颗粒及炎症细胞浸润。结论 Bio-Oss骨有良好的生物相容性和骨引导作用，作为骨移植材料同引导骨再生膜技术联合应用的效果是可靠的。     

引导骨再生术对前牙区种植牙龈美学及牙槽骨吸收的影响

目的 了解前牙美学区种植位点存在骨缺损的患者行引导骨再生术（guided bone regeneration,GBR）在种植术后能否获得无明显骨缺损患者相近的牙龈美学效果,评价引导骨再生术对牙槽骨吸收的影响。方法 选取2017年8月—2018年6月间在中国科学技术大学附属第一医院（安徽省立医院）口腔医学中心行前牙种植术的患者31例,术前测量种植位点牙槽骨宽度,宽度小于6.8 mm的患者为GBR组,宽度大于6.8 mm患者为非GBR组,比较2组二期修复时牙龈美学评分、探诊深度及牙槽骨吸收的差异。采用SPSS 19.0软件包对数据进行两独立样本t检验。结果 GBR组牙龈美学评分显著高于非GBR组（P<0.01）,GBR组与非GBR组探诊深度无显著差异（P>0.05）,GBR组牙槽骨吸收显著小于非GBR组（P<0.01）。结论 使用GBR术可以减缓骨吸收速度,使存在局部牙槽骨缺损的患者达到无骨缺损患者牙种植术后的美学效果。     

Inhibitory effect of 1,25-dihydroxyvitamin D3 on Porphyromonas gingivalis-induced inflammation and bone resorption in vivo

ObjectiveTo investigate whether intragastric administration of 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) could inhibit the bone resorption and inflammation in a mouse calvarial model infected by Porphyromonas gingivalis (P. gingivalis).DesignLive P. gingivalis ATCC 33277 was injected once daily for 6 days into the subcutaneous tissue overlying the calvaria in mice. At the same time, 1,25(OH)₂D₃ (50 μg/kg per day) was administered by gavage for 9 days, starting 3 d before the infection. Mice were killed under ether anesthesia 8 h after the last injection of P. gingivalis. Micro-computed tomography scanning was used to evaluate calvarial bone loss. Tartrate-resistant acid phosphatase was used to detect osteoclast activity. Real-time PCR was used to assess the mRNA expressions of OPG, RANKL, c-Fos, NFATc1, CTSK and TRAP in calvarial bone and IL-6, IL-10, IL-1β, IL-12p40 and TNF-α in soft tissue. The levels of serum IL-6, IL-10 were determined by ELISA.Results1,25(OH)₂D₃ treatment apparently attenuated bone resorption in P. gingivalis-induced mouse calvarial model and markedly reduced the number of osteoclasts. The expression levels of RANKL and osteoclast-related genes such as c-Fos, NFATc1, CTSK and TRAP were also decreased by 1,25(OH)₂D₃. Besides, 1,25(OH)₂D₃ inhibited the expression of pro-inflammatory cytokines IL-6, IL-12p40 and TNF-α and enormously elevated the expression of anti-inflammatory cytokine IL-10.Conclusion1,25(OH)₂D₃ may decrease bone resorption in vivo via suppressing the expression of osteoclast-related genes and its anti-inflammatory properties.     

TNF、IL—1、IL—6刺激培养新生儿小鼠颅盖骨骨吸收的实验研究

目的：研究肿瘤坏死因子、白细胞介素－1、白细胞介素－6对培养的新生小鼠颅盖骨骨吸收的刺激作用。方法：采用器官培养法培养新生儿小鼠的颅盖骨,在3种细胞因子作用48h后,用原子吸收光谱仪测定上清液内钙含量。结果：3种细菌因子在实验浓度范围内均能促进上清 中钙含量增加,并且具有一定的剂量依赖特点,结论：肿瘤坏死因子、白细胞介素－1、白细胞介素－6能够刺激新生小鼠颅盖骨的骨吸收,是与骨吸收密切相关的细胞因子。     

不同时机牙移动对SD大鼠牙槽突裂植骨区骨改建的影响

目的:评价牙移动产生的功能性刺激对SD大鼠牙槽突裂植骨区骨改建的影响,探讨植骨后牙移动的合适时机。方法:选择16只56天的雄性SD大鼠,随机分为4组,按照已建立的外科诱导SD大鼠双侧牙槽突裂模型要求造裂,填塞骨蜡8周后,在双侧裂隙区同时植入大鼠自体髂骨松质骨,左侧为牙移动侧,分别在植骨后即刻、2周、4周、8周近中移动左侧第二磨牙进入植骨区,右侧为对照侧,第二磨牙不进行任何处理。加力牙移动4周后处死动物。通过Micro-CT扫描标本,运用Mimics 10.01软件计算双侧植骨区骨量,采用SAS 9.0软件包对双侧植骨区骨量进行配对t检验,对双侧植骨区骨量的差值进行组间方差分析。结果:各组的牙移动侧植骨区骨量均多于对照侧。0周组牙移动侧与对照侧植骨区骨量差值为0.87mm3,无显著差异(P>0.05);2周组和4周组牙移动侧与对照侧植骨区骨量的差值分别为1.7mm3和1.77mm3,有显著差异(P<0.05);8周组牙移动侧与对照侧植骨区骨量的差值为3.47mm3,有显著差异(P<0.01),8周组两侧植骨区骨量差值的均数与0周组、2周组和4周组均有显著差异(P<0.05)。结论:牙移动对植骨区的功能性刺激能抑制植骨区的骨吸收。植骨8周后的牙移动抑制植骨区移植骨吸收的作用最为明显。     

Healing patterns in calvarial bone defects following guided bone regeneration in rats. A micro-CT scan analysis

OBJECTIVE: The objective of this study was to evaluate healing patterns of critical-size calvarial bone defects treated according to principles of guided bone regeneration using micro-CT scan analysis. Specifically, the contribution of bone, periosteum and dura mater to the amount and mineralization of newly formed bone was evaluated. MATERIAL AND METHODS: Surgically induced, critical-size calvarial bone defects in 48 adult male Wistar rats received the following: an occlusive expanded polytetrafluoroethylene (ePTFE) membrane at the exo- and endocranial aspect (OO; n = 12); an occlusive membrane at the exocranial and a perforated membrane at the endocranial aspect (OP; n = 12); a perforated membrane at the exocranial and an occlusive membrane at the endocranial aspect (PO; n = 12); and a perforated membrane at the exo- and endocranial aspect (PP; n = 12). The animals were euthanized at 4 weeks for quantitative analysis of bone volume fraction and mineralization in the region of interest (ROI) as well as in the external, middle and central area of the defect using micro-CT. RESULTS: Bone volume fraction ranged from 31.4% (OP) to 24.5% (PP). No differences were found among the groups. Bone volume fraction and mineralization in the middle area were significantly greater in group OP than in group PP, and in the central area in group OO and PO than in group PP. CONCLUSIONS: The results of this study suggest that use of occlusive ePTFE membranes enhances bone formation and maturation in the calvarial skeleton. When occlusion of endo- and exocranial tissues was compromised by membrane perforation, impaired bone formation and mineralization were observed.