Lopez Franco Gloria E, Huang Alice, Pleshko Camacho Nancy, Blank Robert D
Endocrinology Section, Department of Medicine, University of Wisconsin, 600 Highland Avenue, Madison, WI 53792, USA.
Bone. 2005 Jun;36(6):1039-46. doi: 10.1016/j.bone.2005.03.004.
Dentinogenesis imperfecta (DI) is a common but variable feature of osteogenesis imperfecta (OI). The Col1a2(oim) mutation (oim) is a well-studied mouse model of chain deficiency OI. Heterozygous oim/+ mice have subtle skeletal fragility, while homozygous oim/oim mice have marked skeletal fragility. To further define the consequences of oim mutation, we examined teeth by light and scanning electron microscopy (SEM). The dental phenotype in Col1a2(oim) (oim) mice is more severe in incisors than in molars and includes changes in pulp chamber size, tooth shape, and dentin ultrastructure. Teeth in oim/oim animals are clinically fragile, while oim/+ teeth are grossly normal. Incisor pulp chamber areas (in mum(2)) are: upper +/+ = 358 +/- 75, lower +/+ = 671 +/- 162, upper oim/+ = 161 +/- 54, lower oim/+ = 156 +/- 19, upper oim/oim = 6900 +/- 1040, and lower oim/oim = 66 +/- 62 (P < 10(-5)). Incisor non-pulp chamber cross-sectional areas (in mum(2)), reflecting dentin areas, are: upper +/+ = 39,000 +/- 1670, lower +/+ = 35,600 +/- 1980, upper oim/+ = 47,500 +/- 2510, lower oim/+ = 26,000 +/- 1830, upper oim/oim = 29,800 + 315, and lower oim/oim = 36,800 +/- 3450 (P < 10(-5)). Ultrastructural abnormalities are more pronounced in incisors than in molars and depend on dosage of the mutant allele. These include reduction in the number and regularity of spacing of the dentinal tubules, lesser mineralization, and blurring of the boundary between peritubular and intertubular dentin. Our findings demonstrate that both oim/oim and oim/+ mice suffer from DI. The more severe incisor phenotype may reflect incisors' continuous growth.
牙本质发育不全（DI）是成骨不全（OI）常见但具有变异性的特征。Col1a2（oim）突变（oim）是一种经过充分研究的链缺陷型OI小鼠模型。杂合子oim/+小鼠有轻微的骨骼脆弱性，而纯合子oim/oim小鼠有明显的骨骼脆弱性。为了进一步明确oim突变的后果，我们通过光学显微镜和扫描电子显微镜（SEM）检查牙齿。Col1a2（oim）（oim）小鼠的牙齿表型在切牙比磨牙更严重，包括牙髓腔大小、牙齿形状和牙本质超微结构的变化。oim/oim动物的牙齿在临床上很脆弱，而oim/+牙齿大体正常。切牙牙髓腔面积（单位为μm²）分别为：上颌+/+ = 358±75，下颌+/+ = 671±162，上颌oim/+ = 161±54，下颌oim/+ = 156±19，上颌oim/oim = 6900±1040，下颌oim/oim = 66±62（P < 10⁻⁵）。反映牙本质面积的切牙非牙髓腔横截面积（单位为μm²）分别为：上颌+/+ = 39000±1670，下颌+/+ = 35600±1980，上颌oim/+ = 47500±2510，下颌oim/+ = 26000±1830，上颌oim/oim = 29800 + 315，下颌oim/oim = 36800±3450（P < 10⁻⁵）。超微结构异常在切牙比磨牙更明显，且取决于突变等位基因的剂量。这些异常包括牙本质小管数量减少和间距规则性降低、矿化程度较低以及管周牙本质和管间牙本质之间边界模糊。我们的研究结果表明，oim/oim和oim/+小鼠都患有DI。切牙更严重的表型可能反映了切牙的持续生长。
