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Functionalisation of Dendrimers
Published in Neelesh Kumar Mehra, Keerti Jain, Dendrimers in Nanomedicine, 2021
Divya Bharti Rai, Deep Pooja, Hitesh Kulhari
Functionalised dendrimers are analogous to protein, enzymes and viruses. In a study, G4.0 PAMAM dendrimers are modified by dimethyl phosphate to obtain phosphate-terminated PAMAM dendrimers (PAMAM-PO3H2) to mimic the structure and surface components of amelogenin protein. Amelogenin is essential for amelogenesis, i.e., development of tooth enamel. The terminal phosphate group of PAMAM-PO3H2 tightly binds enamel and adsorbs calcium ions for deposition on the enamel similar to re-mineralisation of hydroxyapatite (HP), as illustrated by the adsorption test. Moreover, PAMAM-PO3H2 exhibited low toxicity in MTT assay. The enamel incubated with PAMAM-PO3H2 for 20 days was found to have 11.23 thick deposition of HP on the enamel as shown by SEM and X-ray diffraction analysis. The artificial regeneration of tooth was also clinically validated in vivo in the rat oral cavity. Thus, PAMAM-PO3H2 shows great potential as a biocompatible alternative of natural tooth enamel (Chen et al. 2014).
General introduction
Published in Abdulai Salifu, Fluoride Removal from Groundwater by Adsorption Technology, 2017
Intake of excess fluoride (beyond 1.5 mg/L) for long periods can, however, result in negative human health effects. Fluoride has several mechanism of toxicity (Firempong et al., 2013; Shin, 2016; Whirtford, 1996). When it enters into the human body, mainly through the intake of water and to some extent food and dental products, about 75 — 90% is adsorbed (Harder, 2008; Shomer, 2004; Fawell et al., 2006). Ingested fluoride ions initially acts on the gastrointestinal musoca to form hydrofluoric acid (HF) in the stomach by combining with hydrogen ions under the acidic condition in the stomach. The formation of hydrofluoric acid leads to nausea, diarrhoea, vomiting, gastricintestinal irritation and abnominal pains. About 40% of the ingested fluoride is adsorbed from the stomach as HF. Fluoride not adsorbed in the stomach is adsorbed in the instestine. Once absorbed into the blood stream, fluoride readily distributes throughout the body and tend to accumulate in calcium rich areas such as bone and teeth (dentin and enamel) (Fawell et al., 2006; Firempong et al., 2013; Shin, 2016; Gessner et al., 1994). At moderately high levels (1.5 — 4 mg/L) of ingestion, it leads to dental fluorosis, particularly in children. According to Whirtford (1996), even though the mechanisms underlying the development of dental fluorosis are not well understood, there is evidence that the processes probably involve effects on the ameloblasts, which deposit tooth enamel. Ameloblast are cells present during tooth development (in childhood), and secretes the anamel proteins (i.e enamelin and amelogenin), that mineralizes to form the tooth enamel. These cells are observed to be very sensitive to their environment, and bodily stressors (during childhood) can affect their function hence, cause interruption in enamel production. Presumably exposure of children (between the ages of 2 to 8 years old) who are still undergoing mineralization in the permanent teeth to excess fluoride (1.5 — 4 mg/L), is a type of stressor that disrupts the enamel production and results in the development of dental fluorosis (Firempong et al., 2013; Whirtford, 1996; Fawell et al., 2006). Dental fluorosis, which is characterized by discoloured, blackened, mottled or chalky-white teeth, is by far the most common manifestation of chronic use of high-fluoride water. A person affected by dental fluorosis is an indication of overexposure to fluoride during childhood when the teeth were developing (Fawell et al. 2006). These effects are, however, not apparent if the teeth are already fully grown prior to the fluoride overexposure. Therefore if an adult shows no signs of dental fluorosis, it does not necessarily mean his or her fluoride intake is within safety limits and could be at risk of other fluoride-related health hazards.
Advanced materials and technologies for oral diseases
Published in Science and Technology of Advanced Materials, 2023
Hao Cui, Yan You, Guo-Wang Cheng, Zhou Lan, Ke-Long Zou, Qiu-Ying Mai, Yan-Hua Han, Hao Chen, Yu-Yue Zhao, Guang-Tao Yu
HAP and fluoride-containing oral care products can effectively promote enamel remineralization but have no potential to promote the formation of organized apatite crystals. People have recently proposed a therapeutic concept of tooth hard tissue regeneration [81]. Biomimetic remineralization refers to forming HAP crystals mediated by the organic matrix through the interaction of proteins and inorganic materials [82]. For example, amelogenin can direct the formation of highly anisotropic and ordered apatite crystals during enamel development, and the development of amelogenin-based synthetic peptides can increase the remineralization of early enamel lesions [50].