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Abstract Manufacturing of Fränkel's functional regulator 3 (FR3) is complicated and requires extensive knowledge from the dental technician. To determine whether FR3s produced by CAD/CAM techniques (CAD-FR3) meet similar mechanical properties like conventional FR3s (Con-FR3), for each of 10 patient cases, three CAD-FR3 designs (palatal connector cross-section 3 × 3 mm, 4 × 1 mm or 5 × 2 mm) and one Con-FR3 were subjected to cyclic loading and subsequent fracture testing in a universal testing device. Transversal load capacity (Fmax(FR3)) and stiffness were compared among the different CAD-FR3 designs and Con-FR3s using Friedman and Wilcoxon tests with a significance level of α = 0.05. All CAD-FR3 designs had significantly higher mean Fmax(FR3) (p ≤ 0.007) and stiffness (p ≤ 0.005) than the Con-FR3s. The CAD-FR33×3 had the highest mean Fmax(FR3) (98.2 ± 26.2 N) and stiffness (37.1 ± 15.5 N/mm), closely followed by the CAD-FR35×2 (Fmax(FR3): 90.3 ± 24.7 N; stiffness: 30.0 ± 12.3 N/mm). Among the CAD appliances, CAD-FR34×1 had the lowest values (p ≤ 0.007 for all pairwise tests) with Fmax(FR3) of 45.8 ± 17.9 N and stiffness of 12.5 ± 7.3 N/mm. CAD-FR3s have superior mechanical properties in comparison to Con-FR3s if certain design parameters are followed. Further clinical investigations have to examine if they can serve as an alternative in practice.

Objective: Intermaxillary elastics, anchored skeletally, represent a promising concept for treatment in adolescent patients with skeletal Class III anomalies. A challenge in existing concepts is the survival rate of the miniscrews in the mandible or the invasiveness of the bone anchors. A novel concept, the mandibular interradicular anchor (MIRA) appliance, for improving skeletal anchorage in the mandible, will be presented and discussed. Clinical case: In a ten-year-old female patient with a moderate skeletal Class III, the novel MIRA concept, combined with maxillary protraction, was applied. This involved the use of a CAD/CAM-fabricated indirect skeletal anchorage appliance in the mandible, with interradicularly placed miniscrews distal to each canine (MIRA appliance), and a hybrid hyrax in the maxilla with paramedian placed miniscrews. The modified alt-RAMEC protocol involved an intermittent weekly activation for five weeks. Class III elastics were worn for a period of seven months. This was followed by alignment with a multi-bracket appliance. Discussion: The cephalometric analysis before and after therapy shows an improvement of the Wits value (+3.8 mm), SNA (+5°), and ANB (+3°). Dentally, a transversal postdevelopment in the maxilla (+4 mm) and a labial tip of the maxillary (+3.4°) and mandibular anterior teeth (+4.7°) with gap formation is observed. Conclusion: The MIRA appliance represents a less invasive and esthetic alternative to the existing concepts, especially with two miniscrews in the mandible per side. In addition, MIRA can be selected for complex orthodontic tasks, such as molar uprighting and mesialization.

(1) Background: Novel high-performance polymers for medical 3D printing enable in-office manufacturing of fully customized brackets. Previous studies have investigated clinically relevant parameters such as manufacturing precision, torque transmission, and fracture stability. The aim of this study is to evaluate different design options of the bracket base concerning the adhesive bond between the bracket and tooth, measured as the shear bond strength (SBS) and maximum force (Fmax) according to DIN 13990. (2) Methods: Three different designs for printed bracket bases were compared with a conventional metal bracket (C). The following configurations were chosen for the base design: Matching of the base to the anatomy of the tooth surface, size of the cross-sectional area corresponding to the control group (C), and a micro- (A) and macro- (B) retentive design of the base surface. In addition, a group with a micro-retentive base (D) matched to the tooth surface and an increased size was studied. The groups were analyzed for SBS, Fmax, and adhesive remnant index (ARI). The Kruskal–Wallis test with a post hoc test (Dunn–Bonferroni) and Mann–Whitney U test were used for statistical analysis (significance level: p < 0.05). (3) Results: The values for SBS and Fmax were highest in C (SBS: 12.0 ± 3.8 MPa; Fmax: 115.7 ± 36.6 N). For the printed brackets, there were significant differences between A and B (A: SBS 8.8 ± 2.3 MPa, Fmax 84.7 ± 21.8 N; B: SBS 12.0 ± 2.1 MPa, Fmax 106.5 ± 20.7 N). Fmax was significantly different for A and D (D: Fmax 118.5 ± 22.8 N). The ARI score was highest for A and lowest for C. (4) Conclusions: This study shows that conventional brackets form a more stable bond with the tooth than the 3D-printed brackets. However, for successful clinical use, the shear bond strength of the printed brackets can be increased with a macro-retentive design and/or enlargement of the base.