The dental hygienist is responsible for assessing each patient for the risk of caries and then determining a regimen to prevent progression, foster remineralization of the area, or refer for treatment. Flouride has been the primary preventive product for caries. The introduction of calcium phosphates in various delivery modalities has added a new realm of possibilities to the dental hygiene process of care.
The Demineralization Process
Dental caries is a transmittable, infectious disease of teeth caused by acid producing bacteria. Streptococci mutans is the principle microorganism that leads to this destruction. As the pH of the saliva is lowered by these acid producing bacteria, the integrity of the enamel is effected, leading to demineralization.
Tooth enamel is composed almost entirely (97% by weight) of a calcium phosphate mineral in the form of carbonated hydroxyl apatite. The loss of calcium and phosphate from the enamel results in the development of enamel lesions. Remineralization is a deposition of tooth minerals back into the demineralized tooth structure in order to arrest the caries process. Demineralization and remineralization need to be balanced in order to control the progression and reversal of carious lesions. If the demineralization process predominates, the initial caries lesion progresses into cavity formation.
Fluoride and saliva foster remineralization by their protective properties. Fluoride is one of the best defenses against dental caries in children and adults. The highest concentration of fluoride is found in the outermost layer of enamel. Fluoride improves the crystallinity of the apatite structure, which provides a profound effect on the increasing structural stability. Saliva functions as a lubricant and cleanser in protecting teeth. Saliva also buffers the acids and supplies minerals to replace calcium and phosphate that become dissolved during the demineralization process.
Another approach to improve the deposition of minerals into the surface defects of tooth structure and to control caries is amorphous calcium phosphate (ACP). ACP is thought to convert in situ into apatite following its deposit onto the tooth surface, then filling microporosities and microscopic surface defects. Several vehicles for surface deposition of ACP are available, including dentifrices, mouth rinses, prophylaxis pastes, and chewing gum.
Toothpaste containing calcium, phosphate, and fluoride ions is generally more effective in hardening both intact and acidic soft drink-softened tooth enamel compared to conventional toothpaste. This suggests that calcium phosphate toothpaste may provide better remineralization and protective activity on tooth enamel against erosive challenges by acidic material. Most of these studies were done on extracted teeth, thus, further studies on human subjects are indicated.
Chewing gum stimulates salivary flow with its buffering effects. The addition of CPP-ACP (casein phosphopeptide amorphous calcium phosphate complexes) to either sorbitol- or xylitol0based hum resulted in dose related increases in remineralization of the enamel surface. Xylitol is not metabolized by cariogenic bacteria and is proposed to shift the S. mutans bacteria population toward a noncariogenic strain.
The Role of Topical Fluoride
Patients' health histories and their risk of oral diseases should be considered when a regimen of topical fluoride is indicated. The fluoride delivery can be professional or home topical application or professional varnishes. These interventions may also be supplemented with additional fluoride products at home, pit and fissure sealants, or other antibacterial therapy.
A patient with low caries risk might receive a diet analysis, fluoride toothpaste, and oral hygiene instructions, while a patient with moderate or high risk of caries would also receive fluoride mouthrinses, xylitol gum, toothpaste with increased percentage of fluoride, sealants, and/or professionally applied fluoride or varnishes. Each risk factor would be addressed and monitored in conjunction with any required restorative care. Systemic or dietary factors such as xerostomia, exposed root surfaces, eating disorders, and chemotherapy or radiation treatments should be considered in controlling the risk of future caries activity.
The clinical protocols vary depending on the age of the patient and the risk level. Fluoride varnishes should be applied at 6-month intervals for moderate risk children younger than 6 years, while higher risk children may benefit from applications at 3- to 6-month intervals. Adults who are at low caries risk may not receive additional benefit from professional topical fluoride applications. Moderate and high risk adult patients will benefit from varnishes or gels at 3- or 6-month intervals.
When determining how to incorporate the new ACP products into the dental hygiene treatment plan, Dr. Levi will consider the published studies, which build the body of evidence for including ACP in prophy paste, varnishes, toothpaste and chewing gum. Reports published in refereed journals are beginning to indicate correlations of ACP and the resulting anticaries effect.
According to Reynolds, the proposed mechanism of anticariogenicity for the CPP-ACP is that it localizes ACP in dental plaque, which buffers the free calcium and phosphate ion activities, thereby helping maintain a state of super saturation with respect to tooth enamel, depressing demineralization, and increasing remineralization. Reynolds further states that CPP-ACP may have a future potential as an additive to food as well as other oral care products in controlling dental caries.
Research on products like varnish with ACP indicates that the product contains the same amount of 5% sodium fluoride as other fluoride varnishes yet ACP technology actually delivers two times more fluoride uptake into the enamel.
Products that combine ACP into prophy paste or toothpaste might also find the effect of the calcium and phosphate incorporated into the enamel surface where it can remain even after rinsing. Prophy paste that contains ACP reveals that when it is incorporated into the enamel surface, it can stimulate remineralization by preventing damaging erosion.
LeGeros states if demineralization predominates, the initial caries lesion progresses to cavity formation. Remineralization strategies, if applied in a timely manner, can repair or arrest the caries lesion, preventing cavity formation and thus avoiding the necessity for cavity replacement and restoration preparation.
According to Thompson and Kaim, in managing caries risk, the dental professional needs to determine the level of caries risk of the individual patient. A growing body of evidence suggests that noncavitated lesions, even those extending into dentin, can be managed by nonsurgical means, with an expectation for remineralization. Featherstone concludes that keeping the balance toward remineralization is the objective of nonsurgical management of the disease.
The introduction of ACP delivery systems will further enhance remineralization and provide additional benefits toward maintaining a healthy oral environment. The potential benefits remain to be demonstrated and confirmed by randomized clinical trials. Dental hygienists should continue to review the current literature about the impact of incorporating amorphous calcium phosphate into their comprehensive treatment plan.