A combined PIXE and optical microscopy approach was applied to examine the dental calculus of patients with periodontal disease. PIXE was performed with the Bucharest 3 MV Tandetron with 3 MeV protons and a HPGe detector, using hydroxyapatite (HA) and other standards. Sections 30 µm thick were prepared and observed using polarization microscopy and histochemical techniques. Both methods revealed the heterogeneous nature of dental calculus. Two main types (I and II) were postulated based on Ca/P ratios (p < 0.00001). Type I consisted mainly of whitlockite and octacalcium phosphate, whereas type II was mainly HA with some calcium carbonate. They correlated with rodlet masses and amorphous areas with a powdery appearance, observed using microscopy and histochemistry. PIXE also detected two rare forms of calculus (I' and II'). The traces of Zn and S were highly variable. The different types of calculus were probably formed by different biomineralization pathways.

将PIXE和光学显微镜相结合的方法用于检查牙周病患者的牙结石。使用具有3 MeV质子的Bucharest 3 MV Tandetron和HPGe检测器（使用羟基磷灰石（HA）和其他标准品）进行PIXE。准备了厚度为30 µm的切片，并使用偏振显微镜和组织化学技术对其进行了观察。两种方法都揭示了牙结石的异质性。根据Ca / P比（p <0.00001）推测出两种主要类型（I和II）。I型主要由菱锰矿和磷酸八钙组成，而II型主要是HA和一些碳酸钙。使用显微镜和组织化学观察到，它们与小粉状团块和无定形区域相关，且呈粉状。PIXE还检测到两种罕见的微积分形式（I'和II'）。锌和硫的痕迹变化很大。不同类型的牙结石可能是由不同的生物矿化途径形成的。