Bae C-H, Choi H, You H-K, Cho E-S
Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences, Chonbuk National University School of Dentistry, Jeonju, South Korea.
Department of Periodontology, School of Dentistry, Wonkwang University, Iksan, South Korea.
J Periodontal Res. 2017 Jun;52(3):334-341. doi: 10.1111/jre.12396. Epub 2016 Jul 1.
Cellular and acellular cementum and the cells that form them are postulated to have different characteristics, and the relationship between these two tissues is not well understood. Based on the hypothesis that Wnt signaling is involved in the determination of cementum type, we examined Wnt activity along the tooth root and analyzed cementum formation in genetic mutant models.
We generated mutant models with Wnt signaling upregulation ( Catnb ), downregulation ( Wls ), and a compound mutant (Enpp1 ; Catnb ) to compare cementum apposition patterns of ectonucleotide diphosphatase/phosphodiesterase (Enpp1) mutant (Enpp1 ). The analysis of structural morphology and histology was performed with hematoxylin and eosin and immunohistochemical staining and scanning electron microscopy.
The cementum type of upper apical region of tooth roots in the molar is altered from the cellular form at the initial stage to the acellular form at the late stage of cementum formation. However, the basal part of this apical region is not altered and retains cellular cementum characters with strong Wnt activity. In the genetic mutant models for Wnt upregulation, cellular cementum is formed at the cervical region instead of acellular cementum. However, Enpp1 mutant mice have clearly different characteristics with cellular-type cementum even with dramatically increased cervical cementum matrix. In addition, we found that acellular-type formation could be altered into cellular-type formation by analyzing Wnt upregulation and compound mutant models.
Cementum type is not determined by its specific location and could be transformed with Wnt activity during cementum formation.
细胞性和无细胞性牙骨质以及形成它们的细胞被认为具有不同的特征，而这两种组织之间的关系尚未完全明确。基于Wnt信号通路参与牙骨质类型决定的假设，我们检测了沿牙根的Wnt活性，并在基因敲除模型中分析了牙骨质的形成。
我们构建了Wnt信号上调（Catnb）、下调（Wls）以及复合突变（Enpp1；Catnb）的突变模型，以比较外核苷酸焦磷酸酶/磷酸二酯酶（Enpp1）突变体（Enpp1）的牙骨质附着模式。采用苏木精-伊红染色、免疫组化染色和扫描电子显微镜对结构形态和组织学进行分析。
磨牙牙根根尖上部区域的牙骨质类型在牙骨质形成初期为细胞性，后期转变为无细胞性。然而，该根尖区域的基部未发生改变，保留了具有强烈Wnt活性的细胞性牙骨质特征。在Wnt上调的基因敲除模型中，颈部区域形成的是细胞性牙骨质而非无细胞性牙骨质。然而，即使颈部牙骨质基质显著增加，Enpp1突变小鼠的细胞性牙骨质仍具有明显不同的特征。此外，通过分析Wnt上调和复合突变模型，我们发现无细胞性形成可转变为细胞性形成。
牙骨质类型并非由其特定位置决定，而是在牙骨质形成过程中可随Wnt活性发生转变。
