pH of the saliva and biofilm becomes more basic, the equilibrium shifts in the opposite direction to precipitate free ions of calcium and phosphate back into the enamel structure (Figure 3). The natural process of remineralization relies on the level of ions present. Various fluoride products or salivary stimulants can be used to speed this process. Fluoride- releasing restorative materials may also be used. In addition, a newer type of material called alkasite was developed as a bulk-fill bioactive restorative capable of releasing fluoride, calcium, and hydroxyl ions to support remineralization. It comes in a powder- liquid formulation and is utilized like other bulk-fill materials, restoring to a depth of 4 mm. The release of the hydroxyl ions helps regulate pH, making it more alkaline, and aids in prevention of demineralization, as well as facilitating the incorporation of the ions into tooth structure.7 There is limited evidence that alkasites have superior esthetics when compared to glass ionomers. Using any of these materials requires some type of preparation or surgical intervention on the most serious aspect of the lesion. These materials all contain and release fluoride, which contributes to their effectiveness in remineralizing incipient lesions. As seen in Fig- ure 4, fluoride released from these materials is critical to the process because it is incorpo- rated into hydroxyapatite crystals as fluorapatite. The resulting crystals have a greater resistance to caries development because the critical pH for caries development has now decreased to 4.5, as compared to 5.5 for hydroxyapatite crystals (Figure 2, page 43).6 Other remineralizing agents, such as synthetic nanohydroxyapatite, have also shown suc- cess when used in toothpaste. Some chewing gums and mouthrinses may also contain a fluoride booster called casein phosphopeptide-amorphous calcium phosphate (CPP- ACP). This compound helps to keep calcium and phosphate in an amorphous, noncrys- talline state. This amorphous state allows for a supersaturation of the minerals to aid in enamel remineralization.8 Gao et al’s8 systematic review of the literature concludes that sodium fluoride has a proven track record in remineralizing enamel caries, and silver diamine fluoride (SDF) has been shown to effectively arrest dentinal caries. Remineralization of dentin caries presents an additional challenge due to the greater organic content and presence of collagen. In vitro studies have demonstrated that SDF has the ability to enhance remineralization of dentin caries due to its ability to prevent the degradation of collagen.9 Saliva is one of the major factors in neutralizing the effects of an acid attack. Saliva has the ability to dilute, wash surfaces, and act as a buffering agent. It also has antibacterial properties and serves as a repository for the ions aiding remineralization.4 When conditions are right, meaning a near neutral pH, saliva can release ions such as calcium, phosphate, and fluoride to facilitate enamel remineralization. Figure 2 (page 43) summarizes the effect pH has on the rem- ineralization/demineralization cycle, and how it affects the dissolution or integration of calcium, phosphate and fluoride into or out of tooth structure. In addition to releasing ions, saliva also contains valuable proteins, such as statherin, acid proline-rich proteins, and histatins. Statherin is the only salivary protein with the capability to inhibit both primary calcium phosphate precipitation (spontaneous precipitation) and second- ary calcium phosphate precipitation (crystal growth).10 This means statherin can help tip the equilibrium toward remineralization by maintaining calcium and phosphate in a supersaturated state, as well as protecting teeth from calcium phosphate growing in unnecessary places. DIMENSIONS CE 44 Dimensions OF DENTAL HYGIENE • January/February 2024 dimensionsofdentalhygiene.com Belmont Business Media Nationally Approved PACE Program Provider for FAGD/MAGD credit. Approval does not imply acceptance by any regulatory authority or AGD endorsement. July 1, 2023 to June 30, 2026 Provider ID# 317924 AGD Subject Code: 010 Belmont Business Media designates this activity for 2 credit hours of self- study continuing education units. This course is released January 2024 and expires February 2027. Belmont Business Media is an ADA CERP-recognized provider. ADA CERP is a service of the American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. Concerns or complaints about a CE provider may be directed to the provider or to the Commission for Continuing Education Provider Recognition at ada.org/cerp. FIGURE 3. REMINERALIZATION PROCESS. FIGURE 4. REMINERALIZATION PROCESS WITH FLUORIDE.
