Journal of Dentistry Research 2019 | Volume 1 | Article 1007 024 © 2019 - Medtext Publications. All Rights Reserved. ISSN 2688-5549 Dental Applications of Calcium Orthophosphates (CaPO 4 ) Review Article Sergey V Dorozhkin * Kudrinskaja sq. 1-155, Moscow 123242, Russia Citation: Dorozhkin SV. Dental Applications of Calcium Orthophosphates (CaPO4). J Dent Res. 2019; 1(2): 1007. Copyright: © 2019 Sergey V Dorozhkin Publisher Name: Medtext Publications LLC Manuscript compiled: March 11 th , 2019 *Corresponding author: Sergey V Dorozhkin, Kudrinskaja sq. 1-155, Moscow 123242, Russia, E-mail: sedorozhkin@yandex.ru Abstract Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fuorides for dental care. In addition, there is dental erosion, which is a chemical wear of the dental hard tissues without the involvement of bacteria. Besides, there are other dental losses, which may be of a medical (decay or periodontal disease), age (population aging), traumatic (accident) or genetic (disorders) nature. All these cases clearly indicate that biomaterials to fll dental defects appear to be necessary to fulfll customers’ needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Among them, calcium orthophosphates (abbreviated as CaPO4) have some specifc advantages over other types of biomaterials due to a chemical similarity to the inorganic part of both human and mammalian teeth's and bones. Terefore, CaPO4 (both alone and as constituents of various complex formulations) are used in dentistry as both fllers and implantable scafolds. Tis review provides a brief knowledge on CaPO4 and describes in details current state-of-the-art on their applications in dentistry and dentistry-related felds. Among the recognized dental specialties, CaPO4 are most frequently used in periodontics; however, the majority of the publications on CaPO4 in dentistry are devoted to unspecifed “dental” felds. Keywords: Hydroxyapatite; Calcium Orthophosphates; Dentistry; Oral; Fillers; Scafolds; Anti-caries; Bioceramics Introduction Dental caries, also known as tooth decay or a cavity, is an infectious disease (usually of bacterial origin), which causes demineralization and destruction of teeth. If lef untreated, the disease can lead to pain, tooth loss and infection. Historically, this disease is very old and it is not exclusive of the human species. Namely, evidences of dental lesions compatible with caries have been observed in creatures as old as Paleozoic fshes (570-250 million years), Mesozoic herbivores dinosaurs (245-65 million years), prehominines of the Eocene (60-25 million years), as well as in Miocenic (25-5 million years), Pliocenic (5-1.6 million years) and Pleistocenic animals (1.6-10000 million years). Nowadays caries is also detected in bears and other wild animals, as well as it is common in domestic animals [1]. Back to humans, dental caries has been detected in various epochs and societies throughout the world [2-9]. Even though in most developed countries the prevalence of the disease has decreased since the introduction of fuorides for dental care, dental caries remains a major public health problem. Very schematically, dental caries occurs as this. As the most highly mineralized structure in vertebrate bodies, dental enamel is composed of numerous nano-dimensional needle-like crystals of ion-substituted Calcium Orthophosphates (abbreviated as CaPO 4 ) with the apatitic structure (so called “biological apatite”), which are bundled in parallel ordered prisms or rods to ensure unique mechanical strength, remarkable hardness and biological protection. Nevertheless, all types of teeth possess some porosity allowing fuids beneath their surface. Organic (mainly, lactic and acetic) acids, produced by dental plaque cariogenic bacteria (such as Streptococcus mutans and Lactobacillus) from fermentable carbohydrates of sugar or from the remaining food debris, initiate the disease. When the sufcient quantity of acids is produced, so that the solution pH drops below ~ 5.5 (a critical pH), saliva and plaque fuids cease to be saturated with calcium and orthophosphate ions. Tus, dental enamel begins to be demineralized (dissolved) and the aforementioned pores become larger (Figure 1a). Te demineralization process can be described with a simplifed chemical reaction: Ca 10 (PO 4 ) 6 (OH) 2 + H + → Ca 2+ + HPO 4 2- + H 2 O As seen from this reaction, enamel dissolution increases concentrations of both the major ions (calcium and acid orthophosphate) and the minor ones (magnesium, bicarbonate (not shown)) in the local microenvironment of the caries lesions, leading to the formation of various types of acidic CaPO 4 [10-12]. Simultaneously, H + ions are consumed which results in pH increasing. Due to both accumulating of the aforementioned ions in saliva and pH increasing, the demineralization processes of teeth slow down. Several models were developed to simulate dental caries [13-16]. Luckily, saliva has some restorative functions, acting not only as a bufer, to reduce the acidity caused by plaque bacteria, but also as the constant source of soluble ions of calcium and orthophosphate [11,17]. Terefore, upon neutralization of the plaque acids, CaPO 4 complexes from saliva difuse back into the channels between the depleted enamel rods, replenishing the supply of the dissolved ions (Figure 1b). Consequently, the surface of dental tissues is remineralized. Additional application of toothpastes, mouthwashes, mouth rinses, tooth mousses, etc., assists the remineralization. Tus, under normal circumstances, enamel demineralization is compensated by