Characterization of a submandibular gland sialolith: micromorphology, crystalline structure, and chemical compositions. Oral Surg Oral Med Oral Pathol Oral Radiol. 2017;124:e13-e20. [PMID: 28483473 DOI: 10.1016/j.oooo.2017.03.011]

[Narrative review of imaging studies of calcifications of the submandibular gland]

Sialolithiasis is one of the most common pathologies of the major salivary glands and occurs more frequently in the submandibular glands. Between 80 and 95% of sialoliths develop in the submandibular glands, between 5 and 20% in the parotid gland, and only 1% in the sublingual gland. Sialoliths form within the parenchyma and associated duct systems. In Wharton's duct (80-90%) and only 15% in the gland. Sialolithiasis is the cause of pain and inflammation of the salivary gland by obstructing the duct and preventing salivary secretion, before, during and after food.The objective of this article was to review the different diagnostic imaging methods used for the study of calcifications of the submandibular gland, based on different studies reported in contemporary scientific literature, in order to establish the correct diagnosis. A search of the literature was carried out in the main information sources including Medline (via PubMed), SEVIER, SCIELO, and LILACS, using the search terms with a date limitation of the last 5 years on average. The selected articles included information regarding the calcifications of the salivary glands. Imaging studies of salivary gland calcifications can be obtained with conventional radiographs, Sialography, Ultrasonography (US), Computed Tomography (CT) and Magnetic Resonance Imaging (MR).

The roles of heteromorphic crystals and organic compounds in the formation of the submandibular stones

Objective

The study aimed to analyze the formation process of submandibular stones based on the theory of biological mineralization and inorganic crystal structure variation.

Study design

From January 2021 to December 2021, patients with submandibular stones treated in the Affiliated Hospital of Stomatology, Sun Yat-sen University (Guangzhou, China) were selected. According to the criterion of maximum transverse diameter ≥3 mm, a total of five submandibular stones meeting the requirement were included. After the surface of sample stones were washed, they were cut along the maximum transverse diameter. Next, the study employed Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and polycrystalline X-ray Diffraction (XRD) to analyze the composition and structure of submandibular stones.

Results

Five submandibular stones were included. The organic and inorganic compounds showed a rhythmic or irregular distribution. Submandibular stones were highly occupied with carbon (C), oxygen (O), calcium (Ca), and phosphorus (P). Hydroxyapatite (HAP) was the primary inorganic component. In addition, the precursor of HAP, namely Amorphous Calcium Phosphate (ACP), was also found. Tetrahedral Substitution Index (TSI) and Ca/P ratio reflected the degree of structural variation in HAP crystal, which fluctuated from 5.62-90.71 and 1.10-1.35, respectively.

Conclusions

The development of submandibular stones was influenced by inorganic crystals' chemical and structural variation as well as the organics' regulation towards the inorganic. The isomorphic substitution was accompanied by the occurrence of inorganic crystals, resulting in the crystal structure change. Organics might influence the appearance, aggregation, and mineralization of HAP during its formation.

Histopathology and ultrastructural findings of pediatric sialolithiasis: a brief communication

Sialolithiasis is a condition in which the salivary gland excretory duct is obstructed due to the formation of calcareous deposits and is uncommon in children compared to adults. The treatment modalities range from a conservative approach involving hydration to a surgical approach. Though several studies have analyzed the sialolith micromorphology structures, studies on pediatric sialoliths remain scarce. This brief communication aims to describe the sialolith micromorphology to understand the mechanism of mineralization and growth of pediatric sialoliths. A 6-year-old Korean female presented with swelling under her tongue. The intraoral examination revealed a painless yellowish hard mass beneath the tongue near the Wharton’s duct which was suspected as a sialolith. After receiving the informed consent, the sialolithotomy was performed under local anesthesia. The obtained stone was analyzed through histopathology and transmission electron microscope examinations to understand the mechanism of mineralization and growth of pediatric sialolith. The micromorphology and growth processes of pediatric sialolith remain undescribed. More comprehensive microscopic studies are needed regarding their distinctive characteristics. By expanding knowledge about sialoliths micromorphology, development of new preventive, diagnostic and patient-tailored treatment methods of pediatric sialolithiasis will be enhanced.

Salivary duct carcinoma of the submandibular gland presenting a diagnostic challenge: A case report

BACKGROUND

Salivary duct carcinoma (SDC) is a rare, extremely aggressive malignancy that arises in the submandibular gland. It can metastasize locally early and therefore is an important differential diagnosis of metastatic disease in cervical lymph nodes or specific lymphadenitis such as tuberculous cervical lymphadenitis.

CASE SUMMARY

We report a case of SDC in the submandibular gland that presented diagnostic difficulty. The lesion was coincidentally discovered through examination of the radiolucent area of the maxilla. Imaging failed to confirm the possibility of specific inflammation, leading us to execute an open biopsy to verify the diagnosis. The surgical specimen showed that the submandibular gland was primarily replaced with a calcified body. Following histological analysis and confirmation, we performed surgical resection, radiotherapy, and various chemotherapies.

CONCLUSION

Radiographic imaging characteristics of lymph node metastases of salivary gland cancer, especially of SDC, may resemble other cervical lymphadenitis; calcification at the submandibular gland is the landmark of SDC occurring at the subman-dibular gland.

Magnesium whitlockite - omnipresent in pathological mineralisation of soft tissues but not a significant inorganic constituent of bone

Whitlockite is a calcium phosphate that was first identified in minerals collected from the Palermo Quarry, New Hampshire. The terms magnesium whitlockite [Mg-whitlockite; Ca₁₈Mg₂(HPO₄)₂(PO₄)₁₂] and beta-tricalcium phosphate [β-TCP; β-Ca₃(PO₄)₂] are often used interchangeably since Mg-whitlockite is not easily distinguished from β-Ca₃(PO₄)₂ by powder X-ray diffraction although their crystalline structures differ significantly. Being both osteoconductive and bioresorbable, Mg-whitlockite is pursued as a synthetic bone graft substitute. In recent years, advances in development of synthetic Mg-whitlockite have been accompanied by claims that Mg-whitlockite is the second most abundant inorganic constituent of bone, occupying as much as 20-35 wt% of the inorganic fraction. To find evidence in support of this notion, this review presents an exhaustive summary of Mg-whitlockite identification in biological tissues. Mg-whitlockite is mainly found in association with pathological mineralisation of various soft tissues and dental calculus, and occasionally with enamel and dentine. With the exception of high-temperature treated tumoural calcified deposits around interphalangeal and metacarpal joints and rhomboidal Mg-whitlockite crystals in post-apoptotic osteocyte lacunae in human alveolar bone, this unusual mineral has never been detected in the extracellular matrix of mammalian bone. Characterisation techniques capable of unequivocally distinguishing between different calcium phosphate phases, such as high-resolution imaging, crystallography, and/or spectroscopy have exclusively identified bone mineral as poorly crystalline, ion-substituted, carbonated apatite. The idea that Mg-whitlockite is a significant constituent of bone mineral remains unsubstantiated. Contrary to claims that such biomaterials represent a bioinspired/biomimetic approach to bone repair, Mg-whitlockite remains, exclusively, a pathological biomineral. STATEMENT OF SIGNIFICANCE: Magnesium whitlockite (Mg-whitlockite) is a unique calcium phosphate that typically features in pathological calcification of soft tissues; however, an alarming trend emerging in the synthetic bioceramics community claims that Mg-whitlockite occupies 20-35 wt% of bone mineral and therefore synthetic Mg-whitlockite represents a biomimetic approach towards bone regeneration. By providing an overview of Mg-whitlockite detection in biological tissues and scrutinising a diverse cross-section of literature relevant to bone composition analysis, this review concludes that Mg-whitlockite is exclusively a pathological biomineral, and having never been reported in bone extracellular matrix, Mg-whitlockite does not constitute a biomimetic strategy for bone repair.

Ultrasound-guided sialo-irrigation for the treatment of chronic sialodochitis with sialolithiasis

Sialolithiasis is one of the most common causes of salivary duct obstruction. In the last 20 years, minimally invasive procedures like sialendoscopy, extracorporeal lithotripsy, and basket snaring are increasingly being used for the treatment of salivary gland duct stones. Sialo-irrigation of the salivary gland is an effective procedure for treating inflammation and providing symptomatic relief. This procedure can be employed for the treatment of sialolithiasis using the back pressure of instilled saline. Sialo-irrigation under ultrasound (US) guidance allows for dynamic studies showing real-time images during diagnostic or surgical procedure and can be used for the removal of sialoliths. In addition, it can also be used to remove primitive sialoliths and microliths by washing out the ductal system, which prevents the recurrence of sialoliths. The aim of this study was to propose a minimally invasive technique for sialolithiasis using US-guided sialo-irrigation.

Classification of submandibular salivary stones based on ultrastructural studies

INTRODUCTION

Sialolithiasis remains a clinical problem with unclear etiopathogenesis, lack of prevention methods, and only surgical treatment.

MATERIALS AND METHODS

An ultrastructure examination of submandibular sialoliths obtained from patients with chronic sialolithiasis was conducted using a scanning electron microscope and X-ray photoelectron spectroscopy.

RESULTS

Based on the results, we divided sialoliths into three types: calcified (CAL), organic/lipid (LIP), and mixed (MIX). The core structure of the CAL and MIX is very similar. The core of the LIP has a prevalence of organic components. The intermediate layers' structure of the CAL is different from LIP and MIX. In LIP and MIX, the organic component begins to increase in intermediate layers rapidly. The structure of the superficial layers for all types of sialoliths is similar.

CONCLUSIONS

We introduced a new classification of the submandibular salivary gland stones. Based on the results, it can be said that sialoliths type CAL and LIP have their separate path of origin and development, while MIX is formed as CAL stone, and the further pathway of their growth passes as LIP stones. Organic components were much more than inorganic in all layers of salivary gland stones, which highly prevents their dissolution in the patient's salivary gland duct.

Ultrastructural analysis of the submandibular sialoliths: Raman spectroscopy and electron back-scatter studies

The aim of work was the epidemiological analysis of the occurrence of sialolithiasis of the submandibular gland in adults and the evaluation of the ultrastructure of salivary stones. The study sample consisted of 44 sialoliths. Analysis of the structure and chemical composition of sialoliths was performed using a Scanning Electron Microscope and Raman Spectroscopy. Comparing our results with the literature we can say that the epidemiology of sialolithiasis has not changed significantly over the past 50 years. A wide variety of sialoliths structure was observed. In 75% (33) cases a layered structure of salivary stones was observed, while in 25% (11) - homogeneous structure. The various distribution of organic and inorganic components was observed among all the analyzed sialoliths. Raman spectroscopy allows for preliminary analysis of the sialoliths structure with only a qualitative assessment of their composition, which significantly reduces the research value of this method. The presence of organic and inorganic compounds in the core and inner layers of the salivary glands stones confirms 2 basic theories of the formation of sialoliths: inflammation and deposition of the inorganic component as a result of disruption of saliva flow in the salivary glands.