This study compared the ability of two sodium fluoride dentifrices, one containing 5,000 ppm fluoride (Prevident 5000 Plus) and the other 1,100 ppm fluoride (Winterfresh Gel), to reverse primary root caries lesions (PRCLs). A total of 201 subjects with at least one PRCL each entered the study and were randomly allocated to use one of the dentifrices. After 6 months, 186 subjects were included in statistical analyses. At baseline and after 3 and 6 months, the lesions were clinically assessed and their electrical resistance measured using an electrical caries monitor. After 3 months, 39 (38.2%) of the 102 subjects in the 5,000 ppm F– group and 9 (10.7%) of 84 subjects using the 1,100 ppm F– dentifrice, had one or more PRCLs which had hardened (p = 0.005). Between baseline and 3 months, the log10 mean ± SD resistance values of lesions for subjects in the 1,100 ppm F– group had decreased by 0.06±0.55, whereas those in the 5,000 ppm F– group had increased by 0.40±0.64 (p<0.001). After 6 months, 58 (56.9%) of the subjects in the 5,000 ppm F– group and 24 (28.6%) in the 1,100 ppm F– group had one or more PRCLs that had become hard (p = 0.002). Between baseline and 6 months, the log10 mean ± SD resistance values of lesions for subjects in the 1,100 ppm F– group decreased by 0.004±0.70, whereas in the 5,000 ppm F– group, they increased by 0.56±0.76 (p<0.001). After 3 and 6 months, the distance from the apical border of the root caries lesions to the gingival margin increased significantly in the 5,000 ppm F– group when compared with the 1,100 ppm F– group. The plaque index in the 5,000 ppm F– group was also significantly reduced when compared with the 1,100 ppm F– group. The colour of the lesions remained unchanged. It was concluded that the dentifrice containing 5,000 ppm F– was significantly better at remineralising PRCLs than the one containing 1,100 ppm F–.

The aims of this present study were (1) to assess the antimicrobial effect of ozone from a novel ozone–generating device (Heolozone, USA) [0.052% (v/v) in air delivered at a rate of 13.33 ml·s–1] on primary root carious lesions (PRCLs) and (2) to evaluate the efficacy of ozone specifically on Streptococcus mutans and Streptococcus sobrinus. In study 1, 40 soft PRCLs from freshly extracted teeth were randomly divided into two groups to test the antimicrobial effect on PRCLs from exposure to ozonated water for either 10 or 20 s. Half of a lesion was removed using a sterile excavator. Subsequently, the remaining lesion was exposed to the ozonised water for a period of either 10 or 20 s (corresponding to 0.069 or 0.138 ml of ozone, respectively). Using paired Student t tests, a significant (p<0.001) reduction (mean ± SE) was observed in the ozone–treated groups with either a 10–second (log10 3.57±0.37) or 20–second (log10 3.77±0.42) ozone application compared with the control groups (log10 5.91±0.15 and log10 6.18±0.21, respectively). In study 2, 40 sterile saliva–coated glass beads were randomly divided into two groups for each micro–organism. One glass bead was put into each bijou bottle with 3 ml of Todd–Hewitt broth. S. mutans and S. sobrinus were inoculated anaerobically overnight. Each glass bead was then washed with 2 ml of phosphate–buffered saline. Immediately, 10 s of ozone gas was applied to each glass bead in the test groups. There was a significant (p<0.0001) reduction (mean ± SE) in ozone–treated samples for S. mutans (log10 1.01±0.27) and S. sobrinus (log10 1.09±0.36) compared with the control samples (log10 3.93±0.07 and log10 4.61±0.13, respectively). This treatment regime is an effective, quick, conservative and simple method to kill micro–organisms in PRCLs. Ozone gas application for a period of 10 s was also capable of reducing the numbers of S. mutans and S. sobrinus on saliva–coated glass beads in vitro.

There is growing interest in the use of ozone in oral healthcare and the National Institute for Clinical Excellence (NICE) is at present reviewing the evidence for its effectiveness in the management of occlusal and plain surface caries. These are only two of the clinical problems for which ozone can, and has, been used; it has also been employed for a wide variety of other purposes in both dentistry and medicine. This pale blue-coloured gas plays an important role as a natural constituent in the higher layer of the Earth's atmosphere. There is growing evidence that it can be employed as a useful therapeutic agent. This paper reviews its therapeutic uses to date and suggests its possible future clinical applications. Consumer demands for this strong oxidant may increase as the general public becomes increasingly aware of its therapeutic capacity and the non-invasive manner in which it can be administered.

A previous paper, recently published in Primary Dental Care, gave an overview of the medical uses of ozone and outlined some of its uses in dentistry. The current paper focuses on a description of use of ozone in the management of root caries and considers recent studies in this area. There has been relatively limited research into the non-invasive (pharmaceutical) management of root caries. The best management strategy still remains to be developed. Initial studies have indicated that an application of ozone for a period of either 10 or 20 seconds is capable of clinically reversing leathery root carious lesions. It is suggested that, subject to confirmation from extensive trials, this simple and non-invasive technique may benefit many patients with root caries throughout the world since this approach to treat root caries can easily be employed in primary care clinics and in the domiciliary treatment of home-bound elderly people and immobile patients in hospices and hospitals.

Root caries is a widespread problem and can be quite serious in older populations. The restoration of root carious lesions is often difficult. Compared to enamel caries, there has been limited research into the pharmaceutical management of primary root caries lesions (PRCLs), and many of these studies have been carried out in vitro, with limited numbers of clinical trials. Fluoride is presently a cornerstone in dentifrice formulations for cost-effective and anticaries therapy. It is generally accepted that fluoride ions promote remineralization of tooth substances and reduce the rate of demineralization. The use of a dentifrice with a high fluoride content may be considered to reverse PRCLs, since more fluoride is required for the remineralization of roots than for enamel. This paper reviews the effects of dentifrices with high fluoride contents on the management of root caries.