Accuracy of Patient-specific Soft-tissue Prediction Algorithms for Maxillomandibular Surgery in Class III Patients.

Context: Improved esthetics is an important factor for most patients undergoing orthognathic surgery. Thus, a treatment simulation that can provide patients with a realistic view of the esthetic outcome after surgery is important in clinical practice. Aims: To evaluate the accuracy of simulations generated using algorithms specific for patient's type of malocclusion and surgical procedure compared to nonspecific algorithms. Settings and Design: A total of 36 patients (average age 18.41 years) who had undergone maxillary advancement and mandibular setback for Class III malocclusion were included. Subjects and Methods: The presurgical and postsurgical cone-beam computed tomography scans were used to generate the lateral cephalograms and the surgical simulations were created with the patient-specific algorithm (specific for Class III patients) and the nonspecific algorithm (default algorithm not specific for any particular malocclusion or type of surgery) using the treatment simulation feature in Dolphin Imaging software. The accuracy of the simulations was examined by comparing the soft-tissue changes in the surgical simulations with the postsurgical result. Statistical Analysis Used: Statistical analyses were performed with SPSS-software at 0.05 significance level. For the mean difference between the postsurgical and surgical-simulation landmarks, a paired sample t-test (Student's t-test) was performed. Results: Patient-specific algorithms were accurate in vertical prediction of lower lip, B', tip of nose, upper lip, and horizontal prediction of pogonion'. Whereas the nonspecific algorithm was accurate in the horizontal prediction of the lower lip, pogonion', and menton'. Conclusions: Patient-specific and nonspecific algorithms for generating surgical simulations showed different accuracy for vertical and horizontal predictions of the parameters.

Multiloop edgewise archwire treatment for a patient with a severe anterior open bite and amelogenesis imperfecta.

Amelogenesis imperfecta is a rare hereditary disorder that affects dental enamel and is often associated with an anterior open bite. Orthodontic treatment of a 16-year-old female patient with hypocalcified amelogenesis imperfecta and a 9-mm anterior open bite was presented. Radiographic examination revealed a steep mandibular plane angle, an increased lower face height, a Class II skeletal pattern, and a convex profile. Additionally, the patient had stainless steel crowns on all upper and lower posterior teeth and composite veneers on the upper anterior teeth. The patient was treated nonsurgically using a multiloop edgewise archwire (MEAW). MEAW mechanics allowed for successful correction of the anterior open bite, with significant reduction in the mandibular plane angle and improvement in the patient's profile. No fixed retainers were used, and the results remained stable 78 months after removal of orthodontic appliances. MEAW mechanics should be considered for patients with large anterior open bites, although this technique requires excellent patient compliance.

Assessment of automatic cephalometric landmark identification using artificial intelligence.

OBJECTIVE: To compare the accuracy of cephalometric landmark identification between artificial intelligence (AI) deep learning convolutional neural networks (CNN) You Only Look Once, Version 3 (YOLOv3) algorithm and the manually traced (MT) group. SETTING AND SAMPLE POPULATION: The American Association of Orthodontists Federation (AAOF) Legacy Denver collection was used to obtain 110 cephalometric images for this study. MATERIALS AND METHODS: Lateral cephalograms were digitized and traced by a calibrated senior orthodontic resident using Dolphin Imaging. The same images were uploaded to AI software Ceppro DDH Inc The Cartesian system of coordinates with Sella as the reference landmark was used to extract x- and y-coordinates for 16 cephalometric points: Nasion (Na), A point, B point, Menton (Me), Gonion (Go), Upper incisor tip, Lower incisor tip, Upper incisor apex, Lower incisor apex, Anterior Nasal Spine (ANS), Posterior Nasal Spine (PNS), Pogonion (Pg), Pterigomaxillary fissure point (Pt), Basion (Ba), Articulare (Art) and Orbitale (Or). The mean distances were assessed relative to the reference value of 2 mm. Student paired t-tests at significance level of P < .05 were used to compare the mean differences in each of the x- and y-components. SPSS (IBM-vs. 27.0) software was used for the data analysis. RESULTS: There was no statistical difference for 12 out of 16 points when analysing absolute differences between MT and AI groups. CONCLUSION: AI may increase efficiency without compromising accuracy with cephalometric tracings in routine clinical practice and in research settings.

Quantitative evaluation of retromolar space in adults with different vertical facial types.

OBJECTIVE: To investigate the differences in mandibular retromolar space among skeletal Class I subjects with different vertical divergence using cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 123 skeletal Class I patients (aged 20-40 years) were categorized into hypodivergent, normodivergent, and hyperdivergent groups based on S-N/Go-Me and facial height index (FHI). Mandibular retromolar space was measured at four planes parallel to the occlusal plane along the sagittal line and molar cuspal line, respectively. The mandibular retromolar space was compared among the three vertical groups. RESULTS: The hyperdivergent group had a significantly smaller mandibular retromolar space compared with the other two groups, while the hypodivergent group had the largest retromolar space. In addition, the hyperdivergent group had a larger number of subjects whose roots contacted the lingual cortex of the mandibular body. CONCLUSIONS: The hyperdivergent group tends to exhibit the smallest mandibular retromolar space and highest risk of cortex contact. Clinicians should keep in mind that successful molar distalization requires sufficient retromolar space, especially for hyperdivergent subjects, which should be verified with CBCT.

Force decay evaluation of thermoplastic and thermoset elastomeric chains: A mechanical design comparison.

OBJECTIVES: To compare the following over a period of 8 weeks: (1) force decay between thermoplastic (TP) and thermoset (TS) elastomeric chains; (2) force decay between light (200-g) and heavy (350-g) initial forces; and (3) force decay between direct chains and chain loops (stretched from one pin around the second pin and back to the first pin). MATERIALS AND METHODS: TP and TS chains were obtained from American Orthodontics™ (AOTP, AOTS) and ORMCO™ (OrTP, OrTS). Each of the four chain groups was subdivided into four subgroups with 10 specimens per subgroup: (1) direct chains light force, (2) direct chains heavy force, (3) chain loops light force, and (4) chain loops heavy force. The experiment was performed in artificial saliva (pH of 6.75) at 37°C. RESULTS: A significant difference was found between TP and TS chains, with an average mean difference of around 20% more force decay found in the TP chains (P < .001, α  =  .05). There was no significant difference between direct chains and chain loops except in OrTP, in which direct chains showed more force decay. There was also no significant difference in force decay identified when using light vs heavy forces. CONCLUSIONS: TS chains decayed less than TP chains, and chain loop retraction was beneficial only when using OrTP chains. Contrary to the interchangeable use of TP and TS chains in the published literature and in clinical practice, this study demonstrates that they perform differently under stress and that a clear distinction should be made between the two.

The use of temporary anchorage devices for molar intrusion.

BACKGROUND: This article reviews the use of temporary anchorage devices (TADs) for maxillary molar intrusion. TYPES OF STUDIES REVIEWED: The authors reviewed clinical, radiographic and histologic studies and case reports. The studies provided information regarding the application, placement and biological response of orthodontic TADs. RESULTS: TAD-supported molar intrusion is controlled and timely and may be accomplished without the need for full-arch brackets and wires. Supraerupted maxillary first molars can be intruded 3 to 8 millimeters in 7.5 months (approximately 0.5-1.0 mm per month), without loss of tooth vitality, adverse periodontal response or radiographically evident root resorption. CLINICAL IMPLICATIONS: True molar intrusion can be achieved successfully with orthodontic TADs, re-establishing a functional posterior occlusion and reducing the need for prosthetic crown reduction.