Rohanizadeh Ramin, Legeros Racquel Z
Department of Physiology, Bone and Skin Research Group, University of Sydney, Sydney, NSW 2006, Australia.
Arch Oral Biol. 2005 Jan;50(1):89-96. doi: 10.1016/j.archoralbio.2004.07.001.
The attachment of dental calculus to the tooth (enamel or cementum) surface affects the ease or difficulty of its removal. Understanding the ultrastructural features of the calculus-tooth interface will help in the development of efficient strategies for efficient removal of dental calculus.
The aim of this study was to determine the ultrastructural characteristics of the calculus-tooth interface in relation to the occurrence of calculus fracture.
Investigation of the ultrastructural characteristics of the calculus-tooth interface was made on eight human molars with mature supragingival and subgingival calculus using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fourier transform infra-red (FT-IR) spectroscopy.
Fractures were shown by SEM to consistently occur within the calculus itself, but not at the calculus-tooth interface. Higher magnification revealed that the enamel apatite crystals (in the case of supragingival calculus) or the cementum apatite crystals (in the case of subgingival calculus) appeared intimately connected with the calculus crystals at the calculus-enamel or calculus-cementum interface. TEM micrographs confirmed this intimate direct connection or fusion (epitaxial growth) of calculus crystals with enamel and cementum apatite crystals. FT-IR showed lower concentrations of organic phase attributed to microorganisms and higher concentrations of collagen at the calculus-cementum interface compared to that in the calculus away from the interface.
Difficulty in complete calculus removal from tooth surfaces (especially from cementum or dentin) may be due in part to the intimate contact between the calculus and the tooth, due to the chemical bonding between the calculus crystals and the tooth apatite crystals and occasional fusion (i.e., epitaxial growth) of the calculus calcium phosphate crystals with the enamel, dentin or apatite crystals. This cohesive bonding results in fracture planes occurring within the calculus instead of at the calculus-tooth interface.
牙结石附着于牙齿（牙釉质或牙骨质）表面会影响其清除的难易程度。了解牙结石与牙齿界面的超微结构特征将有助于制定高效清除牙结石的策略。
本研究旨在确定牙结石与牙齿界面的超微结构特征与牙结石断裂发生情况的关系。
使用扫描电子显微镜（SEM）、透射电子显微镜（TEM）和傅里叶变换红外光谱（FT-IR）对八颗带有成熟龈上和龈下牙结石的人类磨牙的牙结石与牙齿界面的超微结构特征进行研究。
SEM显示断裂始终发生在牙结石内部，而非牙结石与牙齿的界面处。更高放大倍数显示，在牙结石 - 牙釉质或牙结石 - 牙骨质界面处，牙釉质磷灰石晶体（对于龈上牙结石而言）或牙骨质磷灰石晶体（对于龈下牙结石而言）与牙结石晶体紧密相连。TEM显微照片证实了牙结石晶体与牙釉质和牙骨质磷灰石晶体之间存在这种紧密的直接连接或融合（外延生长）。FT-IR显示，与远离界面的牙结石相比，牙结石 - 牙骨质界面处归因于微生物的有机相浓度较低，而胶原蛋白浓度较高。
难以从牙齿表面（尤其是从牙骨质或牙本质）完全清除牙结石，部分原因可能是牙结石与牙齿之间的紧密接触，这是由于牙结石晶体与牙齿磷灰石晶体之间的化学键合以及牙结石磷酸钙晶体偶尔与牙釉质、牙本质或磷灰石晶体融合（即外延生长）所致。这种内聚性结合导致断裂平面出现在牙结石内部而非牙结石与牙齿的界面处。
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