Facial appearance depends on several oral and extraoral factors. The gingiva is an important intraoral tissue which when affected particularly by pigmentation is mainly responsible for the unpleasant appearance. Several causes of gingival pigmentation were previously mentioned in text together with the possible techniques of treatment. In this review, we will focus on this topic with a histological point of view

Ammi majus, a well-established member of the Umbelliferae (Apiaceae) family, is endogenous to Egypt. The main parts of this plant that are used are the fruits, which contain coumarins and flavonoids as major active constituents. The roots are usually considered by-products that are discarded and not fed to cattle because of coumarins’ potential toxicity. The goal of this study was to ensure the sustainability of the plant, investigate the active metabolites present in the roots using UPLC/MS-MS, isolate and elucidate the major coumarin Xanthotoxin, and predict its oral bioavailability and its potential biological impact on tongue papillae. The results revealed coumarins as the dominant chemical class in a positive acquisition mode, with bergaptol-O-hexoside 5%, Xanthotoxin 5.5%, and isoarnoittinin 6% being the major compounds. However, phenolics ruled in the negative mode, with p-coumaroyl tartaric acid 7%, 3,7-dimethyl quercetin 6%, and hesperidin 5% being the most prominent metabolites. Fractionation and purification of the chloroform fraction yielded Xanthotoxin as one of the main compounds, which appeared as white needle crystals (20 mg). ADME studies for oral bioavailability were performed to predict the potential properties of the compound if used orally. It was noted that it followed Lipinski’s rule of five, had just one parameter outside of the pink area in the radar plot, and was detected inside the threshold area using the boiled egg approach. In vivo, histopathological studies performed on rats showed a notable decrease in the tongue’s keratin thickness from an average of 51.1 µm to 9.1 µm and an average of 51.8 µm to 9.8 µm in fungiform and filiform cells, respectively. The results indicated that although Xanthotoxin is a well-known medical agent with several potential therapeutic activities in oral therapy, it may cause a destructive effect on the structure of the specialized mucosa of the tongue.

Methimazole is an antithyroid drug. It has side effects on many tissues. Bone marrow-derived mesenchymal stem cells (BM-MSCs) are promising in the field of tissue regeneration. To investigate the capacity of BM-MSCs on odontogenic differentiation and dentin regeneration at different time intervals in methimazole treated rats. Twenty-eight male albino rats were classified as: Group I: got distilled water. Group II: obtained therapeutic dosage of methimazole as pro-drug “Neo-Mercazole®”. Group III: received methimazole then solitary injection of BM-MSCs at day 21. Group IV: obtained methimazole and single injection of BM-MSCs at the beginning of the experiment. Light microscope was used to examine specimens. Recently formed collagen and β-catenin-immunoreactivity area% were appraised histomorphometrically and statistically. Histological examination of odontoblasts and dentin illustrated normal structure in Group I and nearly normal features in Group IV. Group II demonstrated discontinuation of odontoblastic layer and areas of different stainability in dentin. Group III showed an evidently wide layer of odontoblast-like cells and distinct dentinal tubules. Masson's trichrome results of dentin in Groups I &IV showed apparently equal areas of new and old collagen. Group II illustrated old collagen mainly. Group III explored new collagen only. β-catenin-immunoreactivity was strong in Groups I & IV, mild in Group II and moderate in Group III. Statistical results revealed that the highest mean of newly formed collagen area% was in Group III, followed by Group I, Group IV then Group II respectively. Regarding β-catenin-immunoreactivity area%, the highest mean was recorded in Group I, subsequently Group IV, next Group III then Group II. Methimazole has destructive consequences. BM-MSCs have a time-based increased capacity for odontogenic differentiation and regeneration of dentin.