ACP: Navigating our way through calcium phosphate technologies

By Lillian Caperila, RDH, MEd, Professional Educator with Premier Dental Products Company

As dental caries continues to challenge the population as well as a seasoned clinician, it becomes imperative that we make better decisions in product efficacy. The next decade brings even smarter technologies that suggest enamel repair and remineralization dependent upon those clinicians who analyze the evidence and clinical science proving their performance.

Advancements in calcium and phosphate technologies emerged in the early 1990’s with the introduction of a dentifrice that contained calcium/phosphate in a dual-tube delivery. Although the product did not endure a competitive, consumer-driven market, it did perform successfully when combined with fluoride treatment used on a study group of older adults undergoing radiation treatment. The xerostomic effects experienced during their treatment placed this group in an extremely high risk for dental root caries. The study conducted under Papas et al, showed improved sites that reversed tooth demineralization when the study group used a vehicle combining ACP (amorphous calcium phosphate) and a fluoride rinse compared to conventional dentifrices containing fluoride alone. (1)The latest products that profess to strengthening enamel will either deliver calcium/phosphate salts in a variety of vehicles or they demonstrate the ability to partner with available fluoride to provide a synergistic result to enamel and dentin structures.

Of all the technologies aimed at enhancing tooth remineralization, fluoride remains the most widely used and thoroughly studied drug of treatment of tooth decay. Several examples of calcium-containing technologies that provide remineralizing benefits include amorphous calcium phosphate and tri-calcium phosphate. (2)Research has shown that the rate of remineralization of enamel increases with the quantity of calcium and phosphate ions in a solution. (3) The role of loosely bound fluoride (calcium fluoride) found concentrated in plaque and saliva can supplement the demineralized tooth structure by providing an improved enamel crystal structure through the formation of acid-resistant, fluoride-rich hydroxyapatite (fluorapatite). This form of incorporated fluoride ion is known as firmly bound fluoride. (4) Amorphous calcium phosphate (ACP) was discovered by ADA Foundation Paffenbarger Research Center chemist and researcher, Ming S. Tung, PhD, in 1991. ACP is the first non-fluoride therapy to remineralize enamel and dentin. (5) The most reactive and soluble calcium phosphate compound, ACP forms on the tooth enamel and within the dentin and dentinal tubules, and also provides a reservoir of remineralizing ions in the saliva. The ACP-forming ingredients also strengthen teeth by acting synergistically to promote more fluoride uptake into the tooth structure as compared to similar fluoride products without ACP. Whereas, tri-calcium phosphate (TCP) formula through a manufacturing process of mechanochemical ball milling of tri-calcium phosphate with fumeric acid will form a barrier that inhibits the calcium from attaching to the fluoride ions. The barrier eventually will break down on the tooth surface and allow the calcium to be readily available. (6)

Upon being applied to the tooth surfaces, both 5% NaF varnish with ACP and 5% NaF varnish with TCP (tri-calcium phosphate) dissolve and release fluoride, calcium and phosphate ions into the saliva and on the tooth surface. As with any fluoride-containing product, these ions will migrate, transfer and move around to lesioned enamel. This “wrap-around” benefit is not isolated to one technology or manufacturer, but is available to all varnishes containing 22,600 ppm of sodium fluoride. The level of availability and fluoride uptake is worth noting and key evidence in guiding our choice of product in patient therapy.The findings of a recent independent study comparing 5% NaF Varnish with ACP and a comparable 5% NaF Varnish that delivers TCP indicated results in the ACP formula achieving 4X more fluoride uptake in the sound enamel than the TCP formula. In addition, the surrounding lesioned enamel obtained remarkable result with both varnishes over the sound enamel, but ACP varnish outcome demonstrated 3X more fluoride uptake over sound enamel and 2X more than the TCP varnish on lesioned enamel. Therefore, the sound enamel is protected and the lesion enamel is getting firmly bound fluoride where it is needed the most. Both fluoride varnishes in this study increased the fluoride content of the enamel over the non-fluoride (control) treatment. However, ACP varnish promoted significantly more fluoride uptake into the enamel (both sound and lesioned) than the TCP varnish. (7)In conclusion, it becomes the responsibility of a knowledgeable and competent clinician to select the products that are clearly supported by clinical evidence to expect success in reversing incipient and demineralized enamel and dentin. Now, as we watch this area of dentistry grow making our choices more complex, it becomes important to remember that our treatment plan should be aimed to improve our client’s health and less on satisfying our own needs during the purchasing process.References
1. Papas A (1), Russell D (1), Singh M (1), Kent R (2), Triol C (3), Winston A (3). Caries clinical trial of a remineralising toothpaste in radiation patients(1) Tufts University School of Dental Medicine, Boston, MA, USA; (2) Forsyth Institute, Boston, MA, USA; (3) Independent Consultants Oral Medicine, Tufts University School of Dental Medicine, Boston, MA, USA2. A.M. Pfarrer and R.L. Karlinsey, “Challenges of implementing new remineralization technologies” Adv. Dent Res. 2009; 21:79 adr.sagepub.com.3. Schemehorn B.R., Orban J.C., Wood G.D., Fischer G.M., “Remineralization by fluoride enhanced with calcium and phosphate ingredients” J Clint Dent, 1997: 76 (Special Issue): 376.4. White, D J, Nancollas, G H, “Physical and chemical considerations of the role of firmly and loosely bound fluoride in caries prevention”, J Dent Res. 1990 Feb; 69 Spec No: 587-94. 5. Garvin J “ACP: the next big thing” ADA News. August 2007: 1, and 10.6. www.indianananotech.com/images/Clinpro_5000_Brochure.pdf7. Dental Product Testing, In. “Final Report, Sound Enamel Fluoride Uptake Study #10-251 Method #40SV”, November 1, 2010.