**4.3.2 ACP-containing bonding cement**

318 Contemporary Approach to Dental Caries

After less successful earlier sealers, findings about the application of a filled-resin sealer (Pro-seal) have been published in the literature. One *in-vitro* study using an acid challenge found that demineralization was significantly less with Pro-seal treatment, compared to an untreated enamel surface (Hu and Featherstone, 2005). In fact, the demineralization levels established by microhardness profiles showed that the Pro-seal group had 98% less demineralization than the control group. This study also featured a group of teeth treated with fluoride varnish. While both the Pro-seal and fluoride varnish had significantly less demineralization than the control group, the sealer had significantly less demineralization than the varnish. Furthermore, the study also found that Pro-seal can stand up to acid challenge and toothbrush abrasion in a laboratory environment. These outcomes were corroborated by another *in-vitro* study, that also found that the filled-resin sealer (Pro-seal) provided significantly more protection than either fluoride varnish or an unfilled resin sealer, with a 92% reduction in lesion depth compared with the controls using polarized light microscopy (Buren *et al.,* 2008). In looking at its supposed fluoride release, one study found that Pro-seal released fluoride ions in a sustained way – with significantly decreasing amounts over a 17-week period, though this release was measured to be sub-ppm (Soliman *et al.,* 2006). Despite some favorable results with *in-vitro* models, no *in-vivo* trials with Pro-

Due to the early stages of this technology, published independent research on the ACP products like MI Paste is limited. Generally, the studies on caries prevention with CPP-ACP consist of *in-situ* caries models with gums, mouthrinses, or lozenges (Iijima *et al.,* 2004; Reynolds *et al.,* 2003). In addition, the vast majority of these studies were carried out by the same group that first isolated CPP-ACP at the University of Melbourne, Australia. For example, using topical applications of CPP-ACP via sugar-free chewing gum and mouthrinse, Reynolds et al. showed that CPP-ACP incorporated into dental plaque can significantly increase the levels of plaque calcium and phosphate ions (Reynolds *et al.,* 2003). Conversely, an *in-vitro* study carried out by an American group found that while fluoride 5000 ppm paste had a statistically significant protective effect against demineralization on enamel sections, MI Paste had no effect (Pulido *et al.,* 2008).There are two published studies that examine the role of CPP-ACP paste in orthodontics. In an *in-vitro* study that assessed the demineralization around bonded molar tubes on extracted third molars, a mild decrease in demineralization was found with the application of CPP-ACP (Sudjalim *et al.,* 2007). On the other hand, the authors of this very article recommended combining CPP-ACP with a fluoride gel to enhance the treatment effect. For the most part, clinicians loyal to the CPP-ACP protocol apply it without a fluoride gel, and the brochures by the manufacturer make no mention of additional rinses or gels. Andersson et al. conducted an *in-vivo* postorthodontic treatment study, in which they compared the remineralization capabilities of 0.05% Sodium Fluoride mouthwash and the application of Topacal (CPP-ACP topical cream) on patients with white spot lesions. The study found significant remineralization with both protocols, and found no significant differences between the groups over time.

**4.2 Resin sealer** 

seal have been published in the literature.

**4.3.1 CPP-ACP paste** 

**4.3 Amorphous calcium phosphate (ACP)** 

As for ACP bonding cement products like Aegis-Ortho, there are currently no published comparative studies on its ability to prevent white spot lesions in the peer-reviewed literature. Two reports detail the questionable bond strength of ACP-containing cement. In spite of its potential benefits, frequent bond failures with ACP-cement have been reported. An *in-vitro* study with an earlier generation of Aegis-Ortho showed that orthodontic brackets bonded to teeth with an ACP-containing composite material failed at significantly lower forces than brackets bonded to teeth with a conventional resin-based composite orthodontic cement (Dunn, 2007). Another *in-vitro* study found that brackets bonded with the conventional Transbond XT had more than two times the shear bond strength in comparison to brackets bonded with Aegis-Ortho cement (Foster *et al.,* 2008). In evaluating the current evidence base for ACP and its various products, the number of published *in-vitro* and *in-vivo* trials is clearly underwhelming. In a 2008 systematic literature review published in the Journal of the American Dental Association (JADA), the authors concluded that there is insufficient clinical trial evidence to make a recommendation regarding the long-term effectiveness of casein derivatives, specifically CPP-ACP, in preventing caries *in-vivo* (Azarpazhooh and Limeback, 2008).
