1. Introduction
White spot (WS) lesions are areas of local decalcification of enamel without cavity formation and are defined as “subsurface enamel porosity from carious demineralization” that is presented as “a milky white opacity” when located on smooth surfaces [
1,
2].
WS are one of the most undesirable side effects in patients undergoing orthodontic therapy. Several studies have demonstrated that WS become visible during the first weeks of orthodontic treatment [
3,
4]. They are usually located around bracket bases, half-moon shaped, but they can also be detected under the molar bands and sometimes can even look like linear defects along the marginal surface of a band [
5,
6]. Brackets, bands, wires, and attachments used during fixed orthodontic therapy, due to their complex design, limits plaque removal and self cleaning. They contribute to the adhesion of oral plaque leading to enamel demineralization [
7].
WS are described as white opaque areas caused by enamel demineralization and are usually located underneath the dental plaque [
8,
9]. This is attributed to the change in optical properties of light reflection of the decalcified enamel [
8]. WS might remineralize over time, but the enamel will not recover its original aspect, thus leading to an unpleasant appearance of the teeth [
10,
11]. The increase of enamel porosity will facilitate bacteria penetration, thus preventing remineralization [
12]. Calcium and phosphate ions that are in this surface can hardly penetrate in between interprismatic spaces to help with the remineralization process [
10]. Similarly, salivary proteins that assist in inhibiting the demineralization process (proteins rich in proline and statherine) cannot easily penetrate in between these pores formed in the enamel. As a result, this sub-superficial demineralization changes the refractory index of the enamel and is clinically manifested as a milky-white opacity area otherwise known as WS [
13,
14]. According to Gorelick, L.; et al. [
5] who studied the incidence of WS lesion in orthodontic patients, the 50% of patients develop at least one WS lesion during their orthodontic treatment. Other studies [
6,
14,
15] demonstrated how the prevalence and the severity (opacity index) of WS would increase in proportion with the prolonging in time of the orthodontic treatment.
There is variation from 2% to 96% in the prevalence of WS, depending on the technique of examination [
5,
10,
14]. WS might be carious or non-carious lesions. WS as carious lesions are clinically presented as rough, opaque, and porous lesions, while WS as non-carious lesions are smooth and polished looking [
8,
16]. Non carious WS lesion include fluorosis, enamel hypomiralization, and enamel hypoplasia. The incidence of WS and caries is significantly influenced by dietary, environmental, and socioeconomic factors, as well as oral hygiene habits [
15,
16]. Therefore, different populations may show even large differences in incidence and prevalence. There is one study conducted in Albania about molar-incisor hypomineralisation (MIH) among children aged 8–10 years [
17], but there is no evidence regarding the occurrence of WS during orthodontic treatment. WS are present during orthodontic treatment, but we do not have evidence if there is a difference in the prevalence of these lesions before and during treatment.
Therefore, the aim of the study was to evaluate the WS lesion prevalence during orthodontic therapy. The correlation between WS and tooth brush habits was also investigated.
4. Discussion
In the present study, the clinical examination, under dental chair light revealed a high prevalence of WS formation during orthodontic treatment (59.5% at T1 and 60.8% at T2), and showed that a higher frequency of oral hygiene maneuvers had a protective effect on the development of WS lesions. This indicated that WS lesions are undoubtedly a major clinical problem in relation to treatment with fixed orthodontic appliances. The high prevalence of WS formation in this study indicated that these lesions are undoubtedly a major clinical problem in relation to treatment with fixed orthodontic appliances. Mizrahi was the one that found a significant rise of the WS prevalence from 72.3% to 84% in patients with fixed orthodontic appliances [
14]. Boersma, J.G.; et al., registered a prevalence of 97% by using the light fluorescence examination technique [
19].
Our study demonstrated also that there were no significant differences between males and females regarding the presence of WS. Females showed a higher presence of WS during orthodontic treatment compared to males, but this difference was not statistically significant. The study conducted by Mizrahi, E. [
14] concluded that there was a significant difference between male and female. Males had an increase in lesion opacity index greater than females. However, there was no significant difference in the prevalence of WS, related to the gender of patients both before and after treatment with fixed orthodontic appliances. Similar gender-related data were found in other studies [
15].
We found that WS lesions during orthodontic treatment were more common in the maxilla. In the maxilla, UR and UL first molars, UL central and lateral incisors, were the most affected teeth. Whereas in the mandible, the LL and LR first molar were the most affected teeth. Lower level of saliva over teeth in maxilla and bigger contact of bands might have influenced the difference of these lesion distribution.
Other authors noticed that these lesions are usually symmetrical and more common in the lateral incisors and maxillary canines as well as in the mandibular canines [
10]. According to Gorelick, L.; et al. maxillary lateral incisors had the highest incidence to develop WS [
5], while Geiger, A.M.; et al. stated that the maxillary lateral incisors and canines were the most affected teeth [
20]. Other studies have shown that the most affected teeth were the first permanent molars, the maxillary incisors, the lateral incisors and the mandibular canines [
21,
22].
In our study, the data about tooth brushing habits was based on patients’ answers about the frequency of brushing. Most of patients (58.1%) under orthodontic treatment reported to brush their teeth twice a day. It was found that a higher frequency of daily tooth brushing was associated to a lower number of observed WS lesions at T1. Kühnisch, J.; et. al. [
23] recommended that eliminating dental biofilm twice daily by tooth brushing with fluoride-containing toothpastes prevents the appearance of new carious lesions. An in vitro study, provided initial evidences that the combination of two innovative oral hygiene tools, may profoundly inhibit adhesion of oral cavity microorganisms onto orthodontic elastics. Also, their growth and biofilm formation onto their surfaces were greatly affected [
24].
The observed prevalence of WS lesion in this study was 59.5% after three months of orthodontic treatment (T1) and increased to 60.8% six months after the orthodontic treatment (T2). Some studies found no association between treatment time and prevalence of WS lesions [
25,
26,
27,
28,
29]. However, there are different attitudes and perceptions from different authors regarding the duration of treatment and the presence of WS during orthodontic therapy. Julien, K.C.; et al., [
15] used a different observation period (24–36 months) for patients undergoing orthodontic therapy. They came to the conclusion that the duration of treatment affected the number of lesions on the teeth. According to a clinical study conducted [
10], it was found a rapid increase in the number of WS appearing in the first 6 months of treatment and a slowdown in the rate of occurrence of these lesions for the next 12 months.
Finally, it is worth noting that the treatment of WS lesions still represents a challenge when striving for aesthetic perfection. However, the aesthetic improvement of both superficial and deeper lesions, is imperceptible. The evaluation of the patient’s oral hygiene before treatment start, as well as a customized prevention regimen for patients at higher risk, is of great importance [
29,
30,
31,
32,
33,
34].
One of the limitations of the present study was that WS were evaluated through visual examination under dental chair light, a technique less sensitive than the use of several optical techniques during recent decades, such as the optical caries monitor, use of quantitative laser and light- induced fluorescence, digital imaging with fiber-optic transillumination, laser fluorescence, and computer analysis of digital photographs. A bigger number of patients selected accorded to age may provide important information about WS correlated to age and tooth brush habits. However, it still represents a reliable first-line examination that is capable to provide a useful insight into the relevance of the risk of WS formation in orthodontic patients. In addition, since the T2 evaluation was performed when the orthodontic appliance was still in place, it is possible that the prevalence of WS might have been underestimated, since WS lesions located under the brackets and/or bands might not have been detected.