Contact ratio and adaptations in the maxillary and mandibular dentoalveolar joints in rats and human clinical analogs.
Contact ratio and adaptations in the maxillary and mandibular dentoalveolar joints in rats and human clinical analogs.
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大鼠和人类临床类似物上颌和下颌牙槽关节的接触比和适应性。
DOI：
10.1016/j.jmbbm.2022.105485
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发表时间：
2022
影响因子：
3.9
通讯作者：
Ho,SunitaP
中科院分区：
文献类型：
--
作者：
Wang,Bo;Nguyen,Nam;Kang,Misun;Srirangapatanam,Sudarshan;Connelly,Stephen;Souza,Richard;Ho,SunitaP
在临床前小型动物模型中，基于功能的接触区域和完整纤维关节骨骼中产生的机械应变的空间图是有限的。本研究对10只雄性Sprague-Dawley大鼠（12周时N = 5, 20周时N = 5）的半下颌骨和半腋窝完整牙槽纤维关节（DAJs）进行了功能成像。评估上颌关节磨牙的骨体积分数（BVF）、骨孔径和孔密度、牙骨质分数（CF）等物理特征。生物力学测试提供了关节刚度的估计，磨牙和骨窝之间牙周韧带间隙（PDL-space）的变化，从而定位各自关节的接触区域。接触区域定位显示关节的机械应力根间和根尖区域。上颌和下颌关节的这些解剖特异性接触应力与物理特征和由此产生的神经根间和骨窝腔室的应变相关。下颌关节间隙总体高于上颌关节间隙，且这一趋势与年龄一致（年轻加载：Mn - 134±55 μm， Mx - 110±47 μm；年老加载：Mn - 122±49 μm， Mx - 105±48 μm）。然而，下颌和上颌关节间隙随年龄（年轻卸载：Mn - 147±51 μm； Mx - 125±42 μm；老年卸载：Mn - 134±46 μm； Mx - 116±44 μm）显著降低（P < 0.05）。下颌根间骨（IR骨）的骨体积分数（BVF）随年龄的增长而显著增加（P < 0.05），冠状下颌骨的孔隙率低于上颌。上颌牙的接触比（接触面积占总表面积）显著大于下颌骨（P < 0.05）；上颌根间和根尖接触率（IR骨：41%，56%；根尖骨：4%，12%）随年龄增长而增加，高于下颌骨（IR骨：19%，44%；根尖骨：1%，4%）。结果较高但均匀的应变在上颌骨对比较低但较高的变异在下颌骨应变在年轻的年龄。骨骼中物理特性和功能应变的解剖特异性共定位提供了与下颌骨材料特性引导的适应性优势相比，上颌形状引导的适应性优势的见解。这些来自临床前动物模型的年龄相关趋势与青少年和成人正畸治疗后下颌颅面骨的年龄和牙齿位置特异性变异相一致。
Spatial maps of function-based contact areas and resulting mechanical strains in bones of intact fibrous joints in preclinical small-scale animal models are limited. Functional imagingin situon intact dentoalveolar fibrous joints (DAJs) in hemimandibles and hemimaxillae harvested from 10 male Sprague-Dawley rats (N = 5 at 12 weeks, N = 5 at 20 weeks) was performed in this study. Physical features including bone volume fraction (BVF), bone pore diameter and pore density, and cementum fraction (CF) of the molars in the maxillary and mandibular joints were evaluated. Biomechanical testingin situprovided estimates of joint stiffness, changes in periodontal ligament spaces (PDL-space) between the molar and bony socket, and thereby localization of contact area in the respective joints. Contact area localization revealed mechanically stressed interradicular and apical regions in the joints. These anatomy-specific contact stresses in maxillary and mandibular joints were correlated with the physical features and resulting strains in interradicular and bony socket compartments.The mandibular joint spaces, in general, were higher than maxillary, and this trend was consistent with age (younger loaded: Mn - 134 ± 55 μm, Mx - 110 ± 47 μm; older loaded: Mn - 122 ± 49 μm, Mx - 105 ± 48 μm). However, a significant decrease (P < 0.05) in mandibular and maxillary joint spaces with age (younger unloaded: Mn - 147 ± 51 μm; Mx - 125 ± 42 μm; older unloaded: Mn - 134 ± 46 μm; Mx - 116 ± 44 μm) was observed. The bone volume fraction (BVF) of mandibular interradicular bone (IR bone) increased significantly with age (P < 0.05) with the percent porosity of coronal mandibular bone lower than its maxillary counterpart. The contact ratio (contact area to total surface area) of maxillary teeth was significantly greater (P < 0.05) than mandibular teeth; both maxillary interradicular and apical contact ratios (IR bone: 41%, 56%; Apical bone: 4%, 12%) increased with age, and were higher than the mandibular (IR bone: 19%, 44%; Apical bone: 1%, 4%) counterpart. Resulting higher but uniform strains in maxillary bone contrasted with lower but higher variance in mandibular strains at a younger age.Anatomy-specific colocalization of physical properties and functional strains in bone provided insights into form-guided adaptive dominance of the maxilla compared to material property-guided adaptive dominance of the mandible. These age-related trends from the preclinical animal model paralleled with age- and tooth position-specific variabilities in mandibular craniofacial bones of adolescent and adult patients following orthodontic treatment.