The purpose of this study was to systematically review the literature regarding the prevalence of malocclusion and different orthodontic features in children and adolescents. Methods: The digital databases PubMed, Cochrane, Embase, Open Grey, and Web of Science were searched from inception to November 2021. Epidemiological studies, randomized controlled trials, clinical trials, and comparative studies involving subjects ≤ 18 years old and focusing on the prevalence of malocclusion and different orthodontic features were selected. Articles written in English, Dutch, French, German, Spanish, and Portuguese were included. Three authors independently assessed the eligibility, extracted the data from, and ascertained the quality of the studies. Since all of the included articles were non-randomized, the MINORS tool was used to score the risk of bias. Results: The initial electronic database search identified a total of 6775 articles. After the removal of duplicates, 4646 articles were screened using the title and A total of 415 full-text articles were assessed, and 123 articles were finally included for qualitative analysis. The range of prevalence of Angle Class I, Class II, and Class III malocclusion was very large, with a mean prevalence of 51.9% (SD 20.7), 23.8% (SD 14.6), and 6.5% (SD 6.5), respectively. As for the prevalence of overjet, reversed overjet, overbite, and open bite, no means were calculated due to the large variation in the definitions, measurements, methodologies, and cut-off points among the studies. The prevalence of anterior crossbite, posterior crossbite, and crossbite with functional shift were 7.8% (SD 6.5), 9.0% (SD 7.34), and 12.2% (SD 7.8), respectively. The prevalence of hypodontia and hyperdontia were reported to be 6.8% (SD 4.2) and 1.8% (SD 1.3), respectively. For impacted teeth, ectopic eruption, and transposition, means of 4.9% (SD 3.7), 5.4% (SD 3.8), and 0.5% (SD 0.5) were found, respectively. Conclusions: There is an urgent need to clearly define orthodontic features and malocclusion traits as well as to reach consensus on the protocols used to quantify them. The large variety in methodological approaches found in the literature makes the data regarding prevalence of malocclusion unreliable.

Insufficient attention is given in the literature to the early treatment of anterior open bite (AOB) subjects receiving orofacial myofunctional therapy (OMT), which aims to harmonize the orofacial functions. This prospective pilot study investigates the effects of OMT on tongue behaviour in children with AOB and a visceral swallowing pattern. The study comprised of 22 children (11 boys, 11 girls; age range: 7.1–10.6 years). They were randomly assigned into OMT and non-OMT subjects. The randomization was stratified on the presence of a transversal crossbite. At baseline (T0), at the end of treatment (T1) and at 6 months after T1 (T2) maximum tongue elevation strength was measured with the IOPI system (IOPI MEDICAL LLC, Redmond, Washington, USA). Functional characteristics such as tongue posture at rest, swallowing pattern and articulation and the presence of an AOB were observed. OMT did significantly change tongue elevation strength, tongue posture at rest, and tongue position during swallowing of solid food. At T2 more OMT subjects had contact between the lower central incisors and their antagonists or palate ( P = 0.036). More OMT subjects performed a physiological pattern of water swallowing than non-OMT children at T1 and T2, although the differences were not significant. Articulation of /s,l,n,d,t/ was not improved by OMT. No interaction between OMT and expansion was found for any of the parameters. OMT can positively influence tongue behaviour. However, further research is recommended to clarify the success of OMT as an adjunct to orthodontic treatment and to identify possible factors influencing the outcome.

The contribution of the force of the lips, cheeks, and tongue is of particular interest in planning treatment. Thus, the aim of this study was to determine if there are differences in lip and tongue pressure as a function of gender, age, Angle classification, characteristics of occlusion, and oral habits. This cross-sectional study comprised 107 subjects (63 females and 44 males), between 7 and 45 years of age (median 15.2 years), seeking orthodontic treatment. The patients were characterized by the variables gender, age, Angle classification, the characteristics of the occlusion, and oral habits. Lip and tongue pressure were measured with a Myometer 160 and the obtained values were statistically analysed (Kruskal–Wallis and Mann–Whitney U-tests) to highlight possible significant differences between the groups. There was a difference in lip pressure between males and females, between the Angle Classes, and between patients with various associated oral habits. Lip pressure was not significantly correlated with age or with occlusal characteristics. There was no evidence for a relationship between tongue pressure and any of the five considered variables. The findings of present study showed statistically significant differences in lip pressure between different orthodontic patients. There was a difference (P = 0.004) in lip pressure between Class I and Class II division 1 subjects. A higher lip pressure exists in males. Lip pressure in subjects with an open lip relationship was lower (P = 0.026) when compared with those with tongue interposition or with no particular habits. Lip pressure was also lower in subjects with lip interposition compared with those with tongue interposition.