Facial morphology is known to be influenced by genetic and environmental factors. Scientific evidence regarding facial parameters in patients with posterior crossbite is lacking. This study aimed to investigate the association between posterior crossbite and facial parameters. This cross-sectional study included 34 adolescents with and 34 adolescents without posterior crossbite in the age range from 13 to 15 years. Facial surface scans were acquired with a 3dMD imaging system, and landmark-based analysis was performed. Data were analyzed using the Mann-Whitney U test and Spearman’s correlations. Individuals in the control group had lower face heights (females: p = 0.003, r = 0.45; males: p = 0.005, r = 0.57). The control group females presented with smaller intercanthal width (p = 0.04; r = 0.31) and anatomical nose width (p = 0.004; r = 0.43) compared with the crossbite group females. The males in the control group had wider nostrils. In the control group, significant correlations among different facial parameters were more common, including the correlations between eye width and other transversal face measurements. On the contrary, the facial width was correlated with nasal protrusion (r = 0.657; p < 0.01) and the morphological width of the nose (r = 0.505; p < 0.05) in the crossbite group alone. In both groups, the philtrum width was linked with the anatomical and morphological widths of the nose. Conclusions: Patients with posterior crossbites have increased face height and different patterns of facial proportions compared with individuals without crossbites.

Objectives: To determine whether intraoral and nasolabial changes after maxillary expansion (ME) can be predicted based on pretreatment morphology. Methods: The treatment group included 10–16-year-old adolescents who received treatment with RPE or MARPE. The RPE group comprised 13 females and nine males with a median age of 13 (interquartile range [IQR]: 11.1–13.8) years, and the MARPE group comprised 13 females and eight males with a median age of 14.4 (IQR: 13.2–15.2) years. Pre-treatment and post-expansion facial and intraoral scans were analysed. Linear regression was performed to assess whether pretreatment parameters were associated with differences in the change in parameters, adjusting for age, sex, and type of ME appliance. Results: The initially increased nostril widths were associated with a greater increase in the anatomical nose width, compared to the patients with decreased nostril widths, by 1.8 mm (p = 0.014) and 1.5 mm (p = 0.039) for the right and left nostrils, respectively. Individuals with reduced nose height (n-sn) experienced greater expansion in the medial rugae width (Tm3), by 0.9 mm (p = 0.001) and 1.3 mm (p = 0.002), compared to the medium- and increased-nose-height groups, respectively. Initially increased medial rugae width was associated with greater increase after ME. On the contrary, the increased maxillary base and intermolar widths were associated with less increase in those parameters. Conclusions: Initially larger distance between the third rugae was associated with a greater increase in the distance after ME, and a smaller distance in the maxillary width was associated with a greater increase after expansion. Larger initial nostril size was associated with a greater increase in the anatomical nose width after ME.