Background: This retrospective study aimed to analyze the frequency and extent of apical root resorptions (EARR) during orthodontic treatment in the upper and lower incisors, as well as lower molars, using orthopantomograms (OPG). Potential influencing factors such as age, gender, root shape, type of orthodontic appliance, and treatment duration were examined as well. Methods: A total of 57 patients who completed their treatment at the orthodontic department of the Goethe University of Frankfurt between 2011 and 2018 were included in the study. These patients had a combined total of 570 teeth, which were divided into two groups. Group 1 consisted of 20 patients (average age at T0: 10.1 ± 1.2 years old) received a one-phase fixed orthodontic treatment using passive self-ligating Damon bracket system (average duration of 2.1 years ± 6 months), while group 2 consisted of 37 patients (average age at T0: 12.4 ± 2.8 years old) underwent a two-phase therapy, which involved a phase-one functional therapy (average duration of 1.7 years ± 6 months) prior to the phase-two fixed orthodontic treatment with the Damon system (average duration of 1.5 ± 4 months) with a total treatment time of 3.2 years ± 7 months. To determine the extent of post-treatment root resorption of the upper and lower incisors, as well as the first lower molars, crown–root ratio was calculated for each tooth using the pre- and post-treatment OPGs. Additionally, each tooth was assigned a degree of resorption according to the Levander and Malmgren classification. The inter-group comparisons were conducted using the Wilcoxon Mann–Whitney U test. Spearman’s correlation analysis was used to assess the relationship between age, treatment duration, and EARR. The association between gender, root morphology, and EARR was evaluated using the Wilcoxon Mann–Whitney U test. For nominally scaled variables, the Chi-square test was used. The statistical significance was set at p < 0.05. Results: No statistically significant differences were seen between groups 1 and 2 regarding the degree of root resorption (p = 0.89). The study found that the average root resorption for all examined teeth was −5.14%, indicating a slight reduction in the length of the tooth roots after orthodontic treatment. However, no significant differences were observed concerning gender, age, type of orthodontic appliance or treatment duration. Comparisons between upper and lower jaws also did not yield statistically significant differences. The majority of teeth in the study exhibited a normal root shape. The short root length and a pipette formed roots were significantly associated with a higher risk of root resorption (p = 0.001). Conclusions: The study’s findings suggest that the two-phase orthodontic treatment does not increase the risk of EARR compared to one-phase therapy significantly. Some degree of root resorption occurred as a result of orthodontic treatment in both groups. Notably, abnormal root forms were identified as influential factors that could help predict the likelihood of root resorption following orthodontic treatment.

Background/Objectives: This prospective intervention study examined the learning effect of using 3D-printed phantom heads with cleft lip and palate (CLP) and upper jaw models with CLP and maxillary plates during a lecture for dental students in their fourth year at J. W. Goethe Frankfurt University. The primary aim was to evaluate the impact of 3D-printed models on students’ satisfaction levels along with their understanding and knowledge in dental education. Methods: Six life-sized phantom heads with removable mandibles (three with unilateral and three with bilateral CLP) were designed using ZBrush software (Pixologic Inc., Los Angeles, CA, USA) based on MRI images and printed with an Asiga Pro 4K 3D printer (Asiga, Sydney, Australia). Two groups of students (n = 81) participated in this study: the control (CTR) group (n = 39) attended a standard lecture on cleft lip and palate, while the intervention (INT) group (n = 42) participated in a hands-on seminar with the same theoretical content, supplemented by 3D-printed models. Before and after the session, students completed self-assessment questionnaires and a multiple-choice test to evaluate knowledge improvement. Data analysis was conducted using the chi-square test for individual questions and the Wilcoxon rank test for knowledge gain, with the significance level set at 0.05. Results: The study demonstrated a significant knowledge increase in both groups following the lecture (p < 0.001). Similarly, there were significant differences in students’ self-assessments before and after the session (p < 0.001). The knowledge gain in the INT group regarding the anatomical features of unilateral cleft lip and palate was significantly higher compared to that in the CTR group (p < 0.05). Conclusions: The results of this study demonstrate the measurable added value of using 3D-printed models in dental education, particularly in enhancing students’ understanding of the anatomy of cleft lip and palate.