Present and future technologies of tooth whitening.

Dental stains can be broadly classified as intrinsic or extrinsic. Intrinsic stains are a result of defects in tooth development, fluorosis, or acquired through the use of tetracycline. Extrinsic stains are localized mainly in the pellicle and are generated by the reaction between sugars and amino acids or acquired from the retention of exogenous chromophores in the pellicle. Three clinical methods are currently used for measuring stain removal and tooth whitening in the development of new whitening technologies: Lobene Stain Index, Shade Guide Color Change, and Minolta ChromaMeter. Professional tooth whitening products rely on proven technologies--35% hydrogen peroxide for in-office power bleaching or 10% to 15% carbamide peroxide for at-home bleaching--to reduce intrinsic stain and change the inherent tooth color. Over-the-counter tooth whitening products use a combination of surfactants, abrasives, anticalculus agents, and low levels of hydrogen peroxide to reduce extrinsic stain and help maintain tooth whiteness after professional treatment. Future technologies for whitening teeth could involve the use of activating agents to enhance the performance of hydrogen peroxide and natural enzymes.

Clearance of sodium lauryl sulphate from the oral cavity.

Sodium lauryl sulphate (SLS) is used in toothpaste and mouth rinses as an emulsifying and surface cleaning agent. SLS has been implicated in an increased incidence of oral irritation in subjects predisposed to recurrent aphthous stomatitis (RAU). Hence, the purpose of this study was to determine the levels of SLS found in the oral cavity following rinsing with an SLS containing mouth rinse and brushing with a SLS containing dentifrice. An analytical method to separate SLS from saliva and other complex systems was developed. The method used high performance liquid chromatography (HPLC) and detection performed using conductivity measurements. Standard curves with known concentrations showed a detection limit of less than 0.4 ug SLS/ml of fluid. 2 clinical studies were conducted to determine the amount of SLS retained in the mouth by a healthy population after rinsing or brushing with commercially available products. The results showed, after rinsing, that 96% of the available SLS from the rinse was recovered in the collected samples within 2 min. Similarly, after brushing, 86% of the SLS contained within the toothpaste was recovered from the collected samples within the first 10 min. These results showed that the amount of SLS retained in the oral cavity was minimal and the contact time between SLS and the oral cavity was very short. A 2nd study was conducted to measure the amount of SLS retained in the mouth by a population susceptible to RAU. After rinsing, 97% of the available SLS was recovered within the first 2 min. Following brushing, 89% of the SLS in the dentifrice was recovered within the first 10 min. These results were comparable to those determined by the study involving the healthy population.

Salivary and plaque triclosan levels after brushing with a 0.3% triclosan/copolymer/NaF dentifrice.

The concentration and elimination rate of triclosan in saliva was assessed as part of a six week clinical study which evaluated the antiplaque efficacy of a 0.3% triclosan/PVM/MA copolymer/NaF dentifrice. On day one of the study the concentration of triclosan in whole saliva was determined at various times after dentifrice use for both the triclosan/PVM/MA copolymer/NaF and placebo dentifrice groups. The results indicated that the salivary triclosan levels ranged from 19.7 micrograms/ml at 5 minutes to 1 microgram/ml at 2 hours after use of the 0.3% triclosan dentifrice. The triclosan elimination curve for saliva exhibited a mono-exponential decline with a half-life of 26 minutes. The plaque content of triclosan, one hour after dentifrice use, which was determined at the end of the study, was found to be relatively high (25 micrograms/g) compared to that seen in saliva at the same time (6.2 micrograms/ml). It was concluded that the 0.3% triclosan/PVM/MA copolymer/NaF test dentifrice provided effective delivery and bioavailability of the antiplaque agent, triclosan. This was based on the relatively high salivary and plaque triclosan levels observed and the concomitant reduction in plaque formation seen at the end of the study.