**3. Measures to counteract this problem**

#### **3.1 Oral hygiene**

314 Contemporary Approach to Dental Caries

One of the most common negative side effects of orthodontic treatment with fixed appliances is the development of incipient caries lesions around brackets and bands, particularly in cases with poor oral hygiene (Fig. 1). Caries lesions typically form around the bracket interface, usually near the gingival margin (Gorelick *et al.,* 1982). Certain bacterial groups such as mutans streoptococci and lactobacilli ferment sugars to create an acidic environment that over time might lead to the development of dental caries. Since orthodontic appliances make plaque removal more difficult, patients are more susceptible to carious lesions. The irregular surfaces of brackets, bands, wires, and other attachments also limit naturally occurring self-cleaning mechanisms, such as movement of the oral

Fig. 1. Incipient caries lesions (white spots) develop around brackets and bands due to poor

Incipient lesions are characterized by their opacity, mineral loss, and decrease of fluorescence radiance when compared to healthy enamel surfaces. Many incipient enamel lesions have a white appearance due to an optical phenomenon caused by mineral loss in the surface and sub-surface that alters the refractive index and increases the scattering of

Studies have shown that white spot lesions can take only one month to develop (Øgaard *et al.,* 1988*;* O'Reilly and Featherstone, 1987; Gorton and Featherstone, 2003). A clinical study reported the prevalence at 50% (Gorelick *et al.,* 1982), while recent investigations put the incidence of white spot lesions in the orthodontic populations studied at 73-95% (Richter *et al*., 2009; Lovrov *et al,* 2007). Orthodontists and patients will notice these lesions after removal of the fixed appliances, especially since the white spots tend to form in the maxillary esthetic zone (Gorelick *et al.,* 1982; Banks and Richmond, 1994). While some studies have reported a decrease in the display of white spot lesions over time post-

light in the affected area, all resulting in greater visual enamel opacity.

**2. White-spot lesions** 

oral hygiene

musculature and saliva (Rosenbloom and Tinanoff, 1991).

The first line of defense against the development of incipient caries lesions has traditionally been patient education, with a special emphasis on optimal oral hygiene. The advocacy organization for orthodontists in the United States known as the American Association of Orthodontists (AAO) has developed patient manuals and a website to provide recommendations for patients undergoing orthodontic treatment (AAO, 2009). Specifically, the website suggests extra time for toothbrushing, specialized tips to get in between the braces, floss threaders, oral irrigators, and over-the-counter mouthrinses. Additionally, the AAO sponsored informed consent form emphasizes the need for excellent oral hygiene and routine visits to the general dentist (AAO, 2005). It also warns that inadequate oral hygiene could result in caries, discolored teeth, and periodontal disease. Finally, the form explains that the aforementioned problems may be aggravated if the patient has not had the benefit of fluoridated water. In many cases, patient education will also include an emphasis on proper diet with reduced intake of sugars. Despite these efforts by the orthodontist and staff members, many patients will still be non-compliant with oral hygiene instructions. Unfortunately, most orthodontists have a limited background in the behavioral basis of compliance (Mehra *et al.,* 1998). Thus, patient non-compliance presents a unique challenge to orthodontic practices.

#### **3.2 Fluoride during orthodontic treatment (rinses, etc)**

In addition to reinforced oral hygiene instructions, orthodontists have turned to various products and preventive measures to reduce this problem. Dental professionals have employed fluoride for years to prevent caries and remineralize enamel in patients. A systematic review found a reduced level of caries and adolescents who have regular supervised rinsing with a fluoride mouthwash (Marinho, 2004). Daily fluoride rinses have shown promising results, and a significant reduction in enamel lesions can be achieved during orthodontic therapy through the daily use of a 10 mL neutral 0.05% sodium fluoride rinse. However, typical patient compliance rates with this protocol have been relatively low (Geiger *et al., 1992)*.

#### **3.3 Fluoride varnish**

Preventive measures that do not require patient compliance would seem to make more sense for the typical orthodontic patient population of adolescents. For some patients, professional fluoride varnish application by orthodontic auxiliaries at routine appointments can in part address this compliance issue (Vivaldi-Rodrigues *et al*., 2006). On the other hand, each application requires over five minutes of chair-time, and whether or not today's high efficiency/high volume orthodontic practice will devote the time and resources to apply this protocol is debatable. Generally however, fluoride varnishes have a proven track record in caries reduction when applied properly. Vanish (3M/Omni) is a very popular 5% NaF white

White-Spot Lesions in Orthodontics: Incidence and Prevention 317

proposed that under acidic conditions, localized CPP-ACP buffers the free calcium and phosphate ions, substantially increasing the level of calcium phosphate in plaque and, therefore, maintaining a state of supersaturation that inhibits enamel demineralization and enhances remineralization (Reynolds *et al.,* 1999). Rose conducted a laboratory experiment in which he showed that CPP-ACP binds well to dental plaque, providing a large calcium reservoir that may inhibit demineralization and assist in subsequent remineralization (Rose,

This technology has entered the orthodontic marketplace in two different forms: resin bracket bonding cement containing ACP and topical paste containing the CPP-ACP complex. Aegis-Ortho, an ACP-including resin bonding cement, has been marketed by Bosworth (Skokie, IL) as a substitute for ordinary bracket bonding cement, with the added benefit of caries prevention. The manufacturer claims that the acidic challenge (pH at or below 5.8) to the surrounding bracket area will trigger the release of calcium and phosphate from the cement, and a supersaturated calcium phosphate matrix will not only inhibit demineralization, but also remineralize the enamel. ACP-filled composite resins have been shown to recover 71% of the lost mineral content of demineralized teeth (Skrtic

A similar chemical process is manifested with MI paste (GC America, Alsip, IL). Instead of residing in the resin cement, the casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is applied topically in the mouth to affected areas. The manufacturer implicates this product not only lesion prevention (applied twice daily after brushing throughout orthodontic treatment), but also claims the patient can expect the complete reversal of such lesions after three months use post-debonding. Additionally, the manufacturer has recommended MI paste for dental patients with xerostomia, dental sensitivity, gastric reflux,

A myriad of *in-vivo* and *in-vitro* studies have been carried out to study the efficacy of preventive measures against white spot lesion formation during orthodontic treatment. Fluoride varnish has by far the strongest evidence base. The potential of fluoride varnish has been evaluated *in-vitro* (Adriens *et al.,* 1990; van der Linden and Dermaut, 1998; Todd *et al.,* 1999; Demito *et al.,* 2004) as well as *in-vivo* (Vivaldi-Rodrigues *et al*., 2006; Øgaard *et al.,* 2001). Generally, investigations carried out *in-vitro* indicate a moderate to strong beneficial effect of the tested varnishes on enamel demineralization. Two *in-vivo* studies have emerged. In a split-mouth prospective study, there was 44.3% less demineralization noted for teeth that had been treated every 12 weeks with fluoride varnish during orthodontic treatment (Vivaldi-Rodrigues *et al.,* 2006). In a double-blinded randomized placebo-controlled trial, Stecksén-Blicks et al. reported that although fluoride varnish did not totally prevent white spot lesion formation, the incidence was significantly reduced in the fluoride varnish group. In addition to differences in study design, the frequency of fluoride application also varied among the studies. Stecksén et al. applied the fluoride varnish at six week intervals, the typical appointment interval for most orthodontic

fluorosis, exposed root surfaces, and as an adjunct to tooth bleaching.

2000).

*et al.,* 1996).

**4. Current level of evidence** 

**4.1 Fluoride varnish** 

patients.

varnish used for prevention of dental caries. The manufacturer advertises the ease of use, lack of an unesthetic yellow color found in other varnishes, enhanced flow characteristics, and its fluoride delivery of 22,600 ppm. Its name comes from an alleged ability to disappear after application. Data gathered by the manufacturer declare greater fluoride release over a 48-hour period in comparison to other fluoride products. To date, Vanish in particular has not been tested in any of the *in-vitro* or *in-vivo* trials in the literature.

#### **3.4 Resin sealer**

Just as sealants have been shown to prevent caries in molars with deep fissures, resin-based sealers have been applied on facial surfaces of bracketed teeth to prevent enamel caries. In addition to the increased chair-time for this procedure, earlier generations of resin sealers have been found to have very low wear resistance. Previous studies have proven that most of the chemically cured sealants (Zachrisson *et al.,* 1979) do not effectively seal smooth enamel surfaces, because of oxygen inhibition of polymerization when the sealant is in contact with the air in a thin layer. Instead, only "islands" of cured sealant remain where resin pooling occurs. Even light-cured sealants (Banks and Richmond, 1994) that were unfilled or lightly filled could not provide any more protection than the chemically cured sealants. A more recent developed product Pro-seal (Reliance, Itasca, IL) has been marketed as a sealer that is more resistant to toothbrush abrasion than earlier generations, since it is a highly filled resin. In patients with poor oral hygiene, Pro-seal can be added before bracket bonding or after bonding. Additionally, the manufacturer claims that Pro-seal releases fluoride, which further enhances its anticariogenic properties.

#### **3.5 ACP/CPP-ACP**

Recently, there has been increased interest and development in calcium phosphate-based remineralization technology (Reynolds and del Rio, 1984; Rosen *et al.,* 1984). One of the newest modalities in preventive dentistry is the introduction of amorphous calcium phosphate (ACP) into methacrylate composites, gum, pastes, and other dental products. Casein is the predominant phosphoprotein in bovine milk and accounts for almost 80 percent of its total protein, primarily as calcium phosphate stabilized micellular complexes (Aimutis, 2004). Several laboratory and animal experiments have investigated the low cariogenic potential and the possible cario-static activity of dairy products (milk, casein, caseinates and cheeses). The use of casein as an anticariogenic additive to food, toothpaste or drinking water has not been implemented because of its adverse organoleptic properties and the large amount required for efficacy (Reynolds, 1998).

Casein phosphopeptide (CPP) contains the cluster sequence of -Ser (P)-Ser (P)-Ser (P)-Glu-Glu from casein (Iijima *et al.,* 2004). CPP does not have the limitations of casein, has the potential for specific anticariogenic activity, and is at least 10 times greater on a weight basis than it is for casein (so not as much is needed for it to be effective). CPP can remarkably stabilize calcium phosphate (which usually is highly insoluble) in a state-forming CPPamorphous calcium phosphate (ACP) complex. There is no conclusive evidence that ACP is an integral mineral component in hard tissues. Its advocates theorize that it likely plays a special role as a precursor to bioapatite and as a transient phase in biomineralization. In solutions, ACP is converted readily to stable crystalline phases such as octacalcium phosphate or apatitic products (Mathew and Takagi, 2001). Reynolds and colleagues have

varnish used for prevention of dental caries. The manufacturer advertises the ease of use, lack of an unesthetic yellow color found in other varnishes, enhanced flow characteristics, and its fluoride delivery of 22,600 ppm. Its name comes from an alleged ability to disappear after application. Data gathered by the manufacturer declare greater fluoride release over a 48-hour period in comparison to other fluoride products. To date, Vanish in particular has

Just as sealants have been shown to prevent caries in molars with deep fissures, resin-based sealers have been applied on facial surfaces of bracketed teeth to prevent enamel caries. In addition to the increased chair-time for this procedure, earlier generations of resin sealers have been found to have very low wear resistance. Previous studies have proven that most of the chemically cured sealants (Zachrisson *et al.,* 1979) do not effectively seal smooth enamel surfaces, because of oxygen inhibition of polymerization when the sealant is in contact with the air in a thin layer. Instead, only "islands" of cured sealant remain where resin pooling occurs. Even light-cured sealants (Banks and Richmond, 1994) that were unfilled or lightly filled could not provide any more protection than the chemically cured sealants. A more recent developed product Pro-seal (Reliance, Itasca, IL) has been marketed as a sealer that is more resistant to toothbrush abrasion than earlier generations, since it is a highly filled resin. In patients with poor oral hygiene, Pro-seal can be added before bracket bonding or after bonding. Additionally, the manufacturer claims that Pro-seal releases

Recently, there has been increased interest and development in calcium phosphate-based remineralization technology (Reynolds and del Rio, 1984; Rosen *et al.,* 1984). One of the newest modalities in preventive dentistry is the introduction of amorphous calcium phosphate (ACP) into methacrylate composites, gum, pastes, and other dental products. Casein is the predominant phosphoprotein in bovine milk and accounts for almost 80 percent of its total protein, primarily as calcium phosphate stabilized micellular complexes (Aimutis, 2004). Several laboratory and animal experiments have investigated the low cariogenic potential and the possible cario-static activity of dairy products (milk, casein, caseinates and cheeses). The use of casein as an anticariogenic additive to food, toothpaste or drinking water has not been implemented because of its adverse organoleptic properties

Casein phosphopeptide (CPP) contains the cluster sequence of -Ser (P)-Ser (P)-Ser (P)-Glu-Glu from casein (Iijima *et al.,* 2004). CPP does not have the limitations of casein, has the potential for specific anticariogenic activity, and is at least 10 times greater on a weight basis than it is for casein (so not as much is needed for it to be effective). CPP can remarkably stabilize calcium phosphate (which usually is highly insoluble) in a state-forming CPPamorphous calcium phosphate (ACP) complex. There is no conclusive evidence that ACP is an integral mineral component in hard tissues. Its advocates theorize that it likely plays a special role as a precursor to bioapatite and as a transient phase in biomineralization. In solutions, ACP is converted readily to stable crystalline phases such as octacalcium phosphate or apatitic products (Mathew and Takagi, 2001). Reynolds and colleagues have

not been tested in any of the *in-vitro* or *in-vivo* trials in the literature.

fluoride, which further enhances its anticariogenic properties.

and the large amount required for efficacy (Reynolds, 1998).

**3.4 Resin sealer** 

**3.5 ACP/CPP-ACP** 

proposed that under acidic conditions, localized CPP-ACP buffers the free calcium and phosphate ions, substantially increasing the level of calcium phosphate in plaque and, therefore, maintaining a state of supersaturation that inhibits enamel demineralization and enhances remineralization (Reynolds *et al.,* 1999). Rose conducted a laboratory experiment in which he showed that CPP-ACP binds well to dental plaque, providing a large calcium reservoir that may inhibit demineralization and assist in subsequent remineralization (Rose, 2000).

This technology has entered the orthodontic marketplace in two different forms: resin bracket bonding cement containing ACP and topical paste containing the CPP-ACP complex. Aegis-Ortho, an ACP-including resin bonding cement, has been marketed by Bosworth (Skokie, IL) as a substitute for ordinary bracket bonding cement, with the added benefit of caries prevention. The manufacturer claims that the acidic challenge (pH at or below 5.8) to the surrounding bracket area will trigger the release of calcium and phosphate from the cement, and a supersaturated calcium phosphate matrix will not only inhibit demineralization, but also remineralize the enamel. ACP-filled composite resins have been shown to recover 71% of the lost mineral content of demineralized teeth (Skrtic *et al.,* 1996).

A similar chemical process is manifested with MI paste (GC America, Alsip, IL). Instead of residing in the resin cement, the casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is applied topically in the mouth to affected areas. The manufacturer implicates this product not only lesion prevention (applied twice daily after brushing throughout orthodontic treatment), but also claims the patient can expect the complete reversal of such lesions after three months use post-debonding. Additionally, the manufacturer has recommended MI paste for dental patients with xerostomia, dental sensitivity, gastric reflux, fluorosis, exposed root surfaces, and as an adjunct to tooth bleaching.
