Mesial Rotation of the Upper First Molar: Association with Anterior Dental Crowding in Mixed and Permanent Dentition

The position of the upper first molar (UFM) is currently considered the "key of occlusion". The purpose of this study was to evaluate the prevalence of the mesiorotated UFM, and its relationship with anterior dental crowding in mixed and permanent dentition. Intra-oral scans of upper dental arches of 180 subjects with mixed dentition and 169 subjects with permanent dentition were retrospectively analyzed to investigate the presence of UFM mesiopalatal rotation and presence of anterior crowding. The occlusal relationship and the presence of caries were also recorded. In subjects with permanent dentition, there was a statistically significant correlation between anterior crowding and UFM mesiopalatal rotation (Pearson's chi-square = 9.03; p = 0.06). Among cases with permanent dentition, subjects with UFM mesiopalatal rotation showed an OR = 3.28 (95% CI = 0.99–10.93; p = 0.042) of moderate/severe anterior dental crowding, respect to subjects without UFM rotation. In subjects with mixed dentition, there was a statistically significant correlation between molar occlusal relationship and UFM mesiopalatal rotation (Pearson's chi-square = 14.98; p = 0.002), and subjects with molar class II showed a OR = 10.2 (95% CI = 2.16–48.22; p = 0.0005) to present UFM mesiopalatal rotation, with respect to subjects with molar class I. UFM mesiopalatal rotation is associated to anterior dental crowding in permanent dentition, and to class II malocclusion in mixed dentition

Short-Term Effects of a Myofunctional Appliance on Atypical Swallowing and Lip Strength: A Prospective Study

Atypical swallowing needs treatment in order to eliminate harmful interferences of the tongue, which prevent the harmonious growth of the stomatognathic system. The purpose of this study was to assess the effects of a functional appliance on the presence of atypical swallowing, analyzing the lip strength and the altered facial mimics. The effects of a myofunctional appliance (the Froggy Mouth) were evaluated on 40 children (6 males; 24 females; mean age 9.6 ± 2.17) with atypical swallowing—with tongue thrust diagnosed by an expert orthodontist—before and during a 6 month treatment. Data were analyzed over time with a paired samples t-test for normally distributed data. After 6 months of treatment, 33 children out of 40 achieved clinical correction of atypical swallowing due to their good compliance, even at an early stage. Seven children showed low compliance and did not obtain any result. Lip strength in compliant subjects went from 190.30 ± 86.04 cN to 489.39 ± 123.36 cN (t = p < 0.001). Facial mimics improved in 28 out of 33 compliant subjects, and four children with the initial diagnosis of labial incompetence achieved correction. This observational study demonstrates the short-term efficacy of this myofunctional appliance in the treatment of atypical swallowing, achieving correction of the facial mimics and labial incompetence with a significant improvement of the lip strength

Mesial Rotation of the Upper First Molar: Association with Anterior Dental Crowding in Mixed and Permanent Dentition

The position of the upper first molar (UFM) is currently considered the “key of occlusion”. The purpose of this study was to evaluate the prevalence of the mesiorotated UFM, and its relationship with anterior dental crowding in mixed and permanent dentition. Intra-oral scans of upper dental arches of 180 subjects with mixed dentition and 169 subjects with permanent dentition were retrospectively analyzed to investigate the presence of UFM mesiopalatal rotation and presence of anterior crowding. The occlusal relationship and the presence of caries were also recorded. In subjects with permanent dentition, there was a statistically significant correlation between anterior crowding and UFM mesiopalatal rotation (Pearson’s chi-square = 9.03; p = 0.06). Among cases with permanent dentition, subjects with UFM mesiopalatal rotation showed an OR = 3.28 (95% CI = 0.99–10.93; p = 0.042) of moderate/severe anterior dental crowding, respect to subjects without UFM rotation. In subjects with mixed dentition, there was a statistically significant correlation between molar occlusal relationship and UFM mesiopalatal rotation (Pearson’s chi-square = 14.98; p = 0.002), and subjects with molar class II showed a OR = 10.2 (95% CI = 2.16–48.22; p = 0.0005) to present UFM mesiopalatal rotation, with respect to subjects with molar class I. UFM mesiopalatal rotation is associated to anterior dental crowding in permanent dentition, and to class II malocclusion in mixed dentition