Patient motivation represents an important factor for orthodontic treatment success, and it is directly associated with patient cooperation regarding care and hygiene instructions provided by the orthodontist. A high level of motivation may decrease brackets failure, a common problem observed in the orthodontic practice that may causes great treatment delays [2, 10, 13, 15,16,17]. Robb et al. (1998)  reported that treatment duration changes up to 46% are related to bracket failure. Literature showed that an increase of 0.3 to 0.6 times in treatment duration could be attributed to each bracket failure [12, 18].
Understanding the type of patients who mostly present bracket breakage and the most prevalent arches and tooth could help the orthodontist to prevent this situation. Therefore, this research included an extensive sample of 199 individuals, which allowed observing the profile of patients who presented more failures during orthodontic treatment, as well as the most affected teeth.
It was found that 20% of patients from the sample presented some bracket breakage at the moment of assessment (Table 1). The literature shows a great variation in the prevalence of failure—from 3.5 to 23%—due to the different variables that may be considered [1, 16,17,18].
When assessing distribution per arch (Table 1), we found a higher bracket failure rate in the lower arch (9.5%), and this result agrees with previous studies [1, 5, 9, 19, 20]. The challenge in maintaining the lower arch dry during bracket bonding, the higher initial crowding, and the occlusal interference may be the causes of greater failure [1, 17, 20].
Overall, considering the areas and teeth more susceptible to breakage and failure, the professional may perform carefully the bonding procedure in these areas, preventing contamination with saliva and placing the bracket without occlusion interference.
In order to verify the level of patient cooperation regarding the instructions received, the VAS was used. A simple method that is easily understood and applicable by evaluators [21,22,23,24]. It was observed that the group of patients that presented bracket breakage (Fig. 1) showed a lower VAS score (median 58.0) than the group without breakage (median 74.4). These data are in accordance with the literature, which states that the number of brackets lost during treatment is inversely related to patient cooperation [10, 12].
Motivation becomes an important factor for great treatment outcomes. This characteristic may be observed even before therapy, when the individual decides to initiate treatment. This motivation may be described as either external, resulting from the pressure from friends or family members, or internal, resulting from a personal desire. This definition is important considering that it is suggested that patients internally motivated are more cooperative [14, 25].
In this research, when assessing patient motivation, we found that the group that sought treatment on their own presented higher VAS scores than the group that was referred by others (Fig. 2). This result could justify the fact that adult patients present lower breakage rate, because normally they seek treatment on their own, while adolescents do it by the indication of parents or other professionals .
In addition, some authors have observed a reduction in bracket failure and improvement in treatment efficiency when interventions with the purpose to improve patient compliance during orthodontic treatment have been implemented .
Considering the age group, it was observed that adult patients presented higher level of cooperation (median 82.2) than adolescents (median 64.5). A study performed in 2009 reported a correlation between patient motivation and level of cooperation during orthodontic treatment, and the most motivated patients were the ones that better followed the instructions provided by the orthodontist . Accordingly, it was reported that 52% of adolescent patients do not follow the treatment instructions provided by the professional .
The aforementioned results could justify the fact that adult patients presented a lower breakage rate (12.3%) than adolescents (25.4%) (Table 4). These values agree with several studies that observed that the incidence of failure of brackets seems to decrease with age and that the level of cooperation of adults is higher, counterbalancing even the greatest mechanical difficulties in their tooth movements [1, 13, 16, 17, 25, 27, 28].
A limitation of our study comprises the evaluation in one time point, although the distribution of patients at various stages of orthodontic treatment could provide an overview of device breakages. In a future study, a long period of evaluation should be performed in order to confirm these findings.
Based on the information above, identifying patients who need to be more motivated along the treatment is a task professionals should not neglect. Spending some time encouraging and motivating patients to increase their level of cooperation with treatment is as important as a good treatment plan and execution.