The clear aligner treatment in the last years has been increasing its relevance and use. The published papers comparing CA with conventional fixed appliances mainly show flaws and lacks including poor methodology with a high risk of bias, the absence of control group or blinding procedures, and small sample size affecting the internal validity and the outcomes of the studies [17].
This questionnaire collected information on the effective use and management of CA focusing not only on differences between orthodontists and general dentists, but also on the type of patients demanding the invisible orthodontic treatment with CA.
The questionnaire was responded by a higher number of orthodontists than general dentists maybe because the topic regarding a specific field of orthodontics, the clear aligner treatment, was well specified in the title of the survey and it has aroused more interest among the specialists in orthodontics than in general dentists. Seventy-nine percent of total respondents was using CA in their practice, and the main part of them was orthodontists (P = 0.004) as expected considering the topic. To note, the main part of general dentists who answered the questionnaire declared to use CA in their practice (65% vs. 35% not using CA), thus only dentists having a previous knowledge on clear aligner treatment seemed to be interested in the survey and accepted to perform it.
Fifty-seven percent of CA users treated less than 10 cases in a year and 67% used CA since less than 5 years. These results maybe depend on less confidence in using a technique different from the conventional multibracket fixed appliances in which the reliability of treatment outcomes and patient compliance were better demonstrated in literature for many decades. The orthodontists responding to the survey seem to have overall more experience than general dentists with more CA cases started in the last 12 months, although the comparison between the two provider groups was not statistically significant. General dentists indicated that information about clear aligners was mainly gained through private courses and less from academic seminars, congress lectures, and book chapters or papers in comparison to the orthodontists, which are conversely more related to the academic environment after their postgraduate program (Table 3). Thus, the interest in the CA treatment seems more widespread among the younger clinicians to whom this technique is taught at postgraduate orthodontic programs or that regularly participate in seminars and congress lectures.
The adults represented the higher percentage of patients treated with CA by both orthodontists and general dentists (97%), and this trend is in agreement with previous studies [2, 4, 6]. Moreover, the treatment with CA was often used in patients with periodontal problems (Fig. 1). Rossini et al. [18] concluded that the periodontal health indexes were significantly improved during CA treatment. Other studies comparing CA with conventional fixed appliances showed that patients treated with clear aligners presented a better periodontal status evaluated by plaque index (PI), pocket probing depth (PD), and the bleeding probing (BOP) compared to patients treated with fixed appliances because of the facilitated oral hygiene with the removable appliances [19]. However, a good oral hygiene education and continuous and repeated professional tooth cleansing are mandatory to get successful combined periodontal and orthodontic treatment [20].
Other categories of subjects treated by the respondents with CA were patients for which a pre-prosthetic orthodontic treatment was required (19%). The treatment with CA may be indicated to plan and visualize the treatment outcomes before starting the multidisciplinary treatment [7]. The teens represented the 27% of patients treated with CA by the respondents. Younger patients are increasingly involved in CA treatment in the last years, although this was not the original idea of this treatment solution [1]. This is maybe due to the major request of invisible orthodontic treatment even in younger patients with a greater awareness of oral health and a consequent greater adherence during active orthodontic treatment with removable appliances. About the orthodontic treatment before and after jaw surgery, the 11% of respondents considered the use of CA. In the literature, there are a few clinical reports in which treatment with CA was combined with surgery in severe cases [21, 22]. However, the survey outcomes demonstrate the widened perspective of CA use even in complex clinical cases.
Overall, the higher percentage of both orthodontists and general dentists reported they were more confident treating class I dental relationships and malocclusions with a mild-to-moderate crowding (Table 4). This confirms previous findings that have shown good confidence of the practitioners in treating a mild crowding than a severe one [15, 16]. Significant variations between the two groups were reported in the treatment of class I with crowding or class I with open bite that orthodontists seemed to be more inclined to treat (Table 5). In comparing data with previous results of Best et al. [16], a major number of orthodontists declared to treat class I and II malocclusions with deep bite.
About the patients’ characteristics, the respondents revealed that CA treatments were mainly performed in females than males (54% females vs. 5% males) (Table 6). This was expected according to previous studies [4, 11]. Moreover, the study of Jeremiah et al. showed that the social interactions and well-being of a young female adult are influenced by a visible orthodontic appliance with no affection by gender of the judges, whereas an appliance with more positive social judgments would be deemed best for social acceptance [23].
The respondents said that the patients demanding for an invisible treatment with CA were mainly aged between 18 and 45 years, as also showed in previous studies [4, 24]. Older adults with more than 45 years represented a good percentage of patients (27%) treated with CA by the respondents, maybe because the functional and esthetical concern is increasing together with the longer and better life in the developed countries (Table 6). The majority of patients were employed full-time, and this was expected to afford the greater CA treatment fees in comparison to conventional labial fixed orthodontic appliances [24].
A high percentage of patients wearing CA seemed to have previously received information about this type of treatment by advertising on social media and network (73%). A lower percentage received suggestions from the doctor himself, or from word of mouth of friend or family member, and in a little percentage through the office marketing (Table 6). Recent studies have underlined the increased relevance of marketing and social media in our working activities. Orthodontists and patients routinely get access to social media and practice websites that are indeed becoming effective marketing and positive communication tool in the orthodontic practice and patient experience [25,26,27]. Twenty-one percent of respondents declared to not use clear aligners in their practice and answered a different series of questions, and the main part of them (69%) would begin using them in the next future (Fig. 2). A little part of them reported to have used CA only in the past and to have no further intention to consider CA as an orthodontic treatment option in their practice. A little percentage of respondents, but still to remark (8%), declared to not know anything about clear aligners, maybe because of younger age or a few years in practice.
The major part of orthodontists reported to not use CA because of the limited orthodontic final treatment outcomes, the higher price in comparison to traditional fixed appliances or the personal less experience.
The insight into the type of malocclusions and patients demanding for CA in the clinical practice was an original point of this survey, and it was underlined which increasingly focus on the esthetic appearance of adults and the importance of advertising and marketing in the great interest in invisible orthodontic treatment with CA. This survey also focused on practitioners not using clear aligners in their practice and the different reasons between the two groups.
A limitation of this study is that the respondents to the survey were more orthodontists than general dentists. The country more represented was Italy, as could be expected considering the sample recruitment method used in the study. Future studies could be performed to widen the sample and to analyze the different treatment duration and outcomes between the two categories of practitioners. Another interesting aspect could be to predict the best patient to treat with CA according to his compliance and motivation.
