## 4 Discussion  
The present report examined the effect of the social media Instagram in improving both the oral hygiene compliance as well as the knowledge on oral health and dietary habits in young orthodontic patients belonging to the so-called generations of \"millennials\" and \"post-millennials\", which generally include youth generations respectively born at the end of the last century and at the beginning of the present one. Subjects of these categories are characterized by a widespread resort to social media as a form of communication. In particular, Instagram was chosen in this study because it is the most common platform nowadays [9]. After the application of multibrackets appliances, a worsening of the oral hygienic conditions of the patient generally occurs [36]. In addition to the verbal information and motivation, the strategy used to promote oral hygiene compliance in the intervention group of this study was that of sharing on Instagram multimedia contents consisting of pictures and short videos with written explanations, to analyze whether this latter action could be more effective than the traditional verbal communication. A variation of the compliance was clinically assessed through oral health indicators (BI, MGI, and PI) whereas a multiple-choice questionnaire investigated the improvements in patients' knowledge. The first null hypothesis of the present investigation was accepted. For both the trial and control group, and therefore independently of the system used by the clinician to give information, results demonstrated significantly lower BI, MGI, and PI scores at T1 (one month after baseline point) compared to those shown at T0, with no significant differences between the groups. Moreover, no significant differences were revealed between T1, T2 (three months after T0), and T3 (six months after T0), neither within each group nor between the two. These data suggest that oral hygiene instructions and motivation performed at  
Figure 5: Frequency distributions of questionnaire answers. the initial appointment, rather than afterwards, play the most important role in improving clinical indexes since after the initial step average values remained constant. No influence has been shown as regards the method used to communicate with the patient. Many authors have tried to find the most appropriate ways for maintaining patients' compliance, considering that an ineffective plaque control can lead to undesired effects such as gingival inflammation and dental caries. In order to prevent the most frequent consequences due to plaque build-up during a fixed orthodontic treatment, different studies have evaluated the efficacy of text message reminders demonstrating significant lower BI, MGI, and PI scores after different times [31, 37, 38]. [PERSON] et al., [39] also showed the positive influence of these tools when used twice a week for a period of three months to stress the usage of intermaximillary elastics in the treatment of Class II malocclusions. However, text messages belong more to past years and generations, whereas in the present era social media are the dominating way of communicating and they could be more appropriate especially for millennials and post-millennials since they spent most hours of their day right on these online platforms. Until now, there has been quite little research on the efficacy of social media in relation to orthodontics, but a recent systematic review stated that information about orthodontics and other psychosocial factors related to orthodontic patients are spread on social media [40]. A study assessing their usage among patients and practitioners, as well as their potential benefit in marketing and communication strategies, has included Instagram [41]. Moreover, [PERSON] et al., [42] stated that social media, especially Instagram, were preferred by adolescents to receive oral health information.