**4. Studies evaluating the prevalence of white spot lesions**

According to the first studies in this area, buccal and lingual surface lesions were found to be higher in individuals who received orthodontic treatment than in individuals who did not receive treatment. On the other hand, no significant difference was observed in the number of caries [27].

In another study, it was stated that the prevalence of decalcification among patients ranged from 2 to 96%. The reason for this great difference; the variety of methods used to assess the presence of decalcification, the presence of idiopathic lesions, and the use of a fluoride agent during treatment are indicated. Because in cross-sectional study design (orthodontic patients after treatment compared with another group of patients who have not had orthodontics), it is difficult to differentiate between idiopathic white spots and decalcification, which artificially increase the prevalence [7].

Though Zachrisson et al. [28] was the one who examined newly formed white spot lesions with the prevalence ranging from 15 to 89. In the study using photo reviews in assessment [29, 30], the prevalence of WSL was found to be 0–24%. The distribution of affected teeth has been studied [31] and has found that the maxillary incisors and the mandibular first molars to be the teeth with the highest prevalence. In another study [32], it has been stated that the lesions are concentrated in the cervical and middle third of the vestibule surface. In another study, the prevalence of WSL was found to be highest in permanent first molar teeth [33]. Contrary to these findings, in another study [34], it was stated that maxillary lateral and canines were affected too much.

In the literature, the effect of the material used to bond orthodontic bands on enamel has been investigated, but it has been stated that the main reason for WSL formation is the loss of cement integrity and the accumulation of bacteria in the area [35].

Gorelick et al. conducted a study on the incidence of white spot lesions at 6 and 12 months in patients undergoing orthodontic treatment. In their study using the visual examination technique, they reported that 50% of the patients had one or more BNL at the end of the treatment [31]. Boersma et al. [36] investigated the prevalence of white spot lesions after orthodontic treatment using quantitative light fluoroscopy and reported that 97% of patients had one or more lesions. A total of 38% of the patients had BNL 6 months after the treatment. It was stated that this rate increased to 46% in the 12-month group. Only 11% of the control group had at least one occurrence of WSL. Most patients undergoing orthodontic treatment had at least one white spot lesion in a mild form, however, a few patients presented with moderate or severe demineralization.
