Table 2_Evolutionary conformation model of salivary gland lithiasis.docx

IntroductionSalivary stones, or sialoliths, are calcified concretions forming within salivary glands and their ducts through a two-stage process: an initial formation of a central core via precipitation of inorganic material mediated by organic substances, followed by layering of additional organic and inorganic material. Substrates for sialolith formation include mucoid agglomerates, organic vesicles, foreign bodies, and bacterial biofilms. Understanding the detailed structure of sialoliths may aid in developing specific preventive or therapeutic strategies.
Materials and methodsThis study analyzed 137 sialoliths from 102 patients treated across three university hospitals. Stones were extracted via sialendoscopy, direct extraction, or spontaneous extrusion. Structural and compositional analyses were conducted using scanning electron microscopy (SEM-EDX) and x-ray diffraction (XRD).
ResultsMost sialoliths were from the submandibular gland (82%), with the remainder from the parotid gland (18%). Parotid stones predominantly exhibited irregular shapes, while submandibular stones were generally ellipsoidal. All stones demonstrated an oolitic structure characterized by a central core surrounded by concentric layers and frequently associated with bacteria. Mineral composition predominantly included octacalcium phosphate (OCP), hydroxyapatite, and whitlockite. Larger sialoliths exhibited a higher proportion of hydroxyapatite, indicating increased crystallinity compared to OCP.
DiscussionDespite diverse origins and locations, sialoliths share common morphological and compositional traits. Their formation begins with heterogeneous nucleation of calcium phosphates around organic spherules, likely induced by bacterial biofilms. These initial nuclei aggregate into a central core upon which additional layers of organic and inorganic materials deposit progressively. This layering increases the size and crystallinity of the sialoliths over time. The coexistence of amorphous phases and structural heterogeneity within layers explains the variability among stones. Detailed SEM-EDX analysis supports a unified conformational model for sialoliths that integrates the interplay of organic substrates, inorganic minerals, bacterial biofilms, and temporal factors.
ConclusionsSialoliths are oolitic aggregates featuring a central core surrounded by concentric layers composed of organic and inorganic materials. Their formation process involves initial heterogeneous nucleation, bacterial influence, and progressive crystallization. This universal conformational model effectively describes sialolith formation irrespective of patient-specific or anatomical variations.

引言：唾液结石（sialoliths）是在唾液腺及其导管内形成的钙化凝结物，其形成过程分为两个阶段：首先由有机物质介导无机物质沉淀形成核心，随后逐层沉积额外的有机与无机物质。唾液结石形成的底物包括黏液聚集体、有机囊泡、异物以及细菌生物膜。明确唾液结石的精细结构，有助于开发针对性的预防与治疗策略。
材料与方法：本研究对来自三家大学附属医院的102例患者的137枚唾液结石进行了分析。结石通过唾液腺内镜术（sialendoscopy）、直接取出术或自行排出的方式获取。采用扫描电子显微镜-能量色散X射线光谱（SEM-EDX）与X射线衍射（XRD）开展结构与成分分析。
结果：绝大多数唾液结石取自下颌下腺（占比82%），剩余18%取自腮腺。腮腺结石多呈不规则形态，而下颌下腺结石多为椭圆形。所有结石均表现出鲕状结构（oolitic structure）：以核心为中心，周围环绕同心层状结构，且常与细菌共存。矿物成分主要包括八钙磷酸酯（OCP）、羟基磷灰石（hydroxyapatite）以及白磷钙矿（whitlockite）。体积较大的唾液结石中羟基磷灰石占比更高，相较于八钙磷酸酯，其结晶度也更高。
讨论：尽管唾液结石的起源与发生部位存在差异，但它们具有共通的形态与组成特征。其形成始于有机微球周围磷酸钙的异质成核，该过程大概率由细菌生物膜诱导。这些初始核聚集形成核心，随后有机与无机物质逐层在核心表面沉积。随着时间推移，这种层状沉积过程会使唾液结石的体积与结晶度不断提升。层内非晶相与结构异质性的共存，可解释不同结石之间的差异性。细致的SEM-EDX分析结果，支持了一套统一的唾液结石形成构象模型，该模型整合了有机底物、无机矿物、细菌生物膜以及时间因素之间的相互作用。
结论：唾液结石属于鲕状聚集体，以核心为中心，周围环绕由有机与无机物质构成的同心层状结构。其形成过程涵盖初始异质成核、细菌介导作用以及逐步结晶三个环节。该通用构象模型可有效描述唾液结石的形成过程，不受患者个体差异或解剖位置差异的影响。