Journal of Aligner Orthodontics, 04/2024

A 32-year-old woman with a hyperdivergent Class III malocclusion, a Class III molar relationship, mild anterior open bite and crossbite, mandibular midline deviation and a high mandibular plane angle underwent clear aligner treatment. The molar relationship was almost full-cusp Class III on the right side and cusp-to-cusp Class III on the left side. Two treatment plans (orthognathic surgery and orthodontic camouflage) were proposed, and the patient opted for orthodontic camouflage with clear aligners. Mandibular molar distalisation was prescribed and mini-implants were placed in bilateral buccal shelf regions to facilitate it. With anticlockwise rotation of the occlusal plane and maintenance of the mandibular plane, a Class I molar relationship was achieved and the mandibular midline deviation was corrected, with a normal horizontal and vertical overlap. The clear aligner treatment lasted for 27 months with 104 (75 + 29) aligners. The patient was satisfied with the treatment outcome. This case report suggests that delicate control of the occlusal and mandibular planes is crucial for Class III hyperdivergent patients treated with combined clear aligner therapy and mini-implants. Keywords: Class III malocclusion, clear aligner treatment, hyperdivergent, mini-implants, occlusal plane control

In recent years, there has been a surge in research dedicated to understanding the mechanisms of and determining the optimal treatment strategies for skeletal Class II malocclusion. Simultaneously, the implementation of invisible functional appliances in clinical settings has gained popularity, largely due to the comfort and aesthetic benefits they offer. These therapeutic appliances employ either occlusal splints or precision locks or wings that create inclined planes to advance and stabilise the mandible into a predetermined position, which further promotes neuromuscular adaptation and, consequently, modifications to the maxillomandibular positional relationship. This study describes the treatment regimen and outcomes for two skeletal Class II malocclusion cases that utilised the Herbst-derived invisible S8-SGHB device implemented by Smartee Denti-Technology (Shanghai, China). Keywords: biphasic integration treatment, functional arch orthopaedics, mandibular advancement, skeletal Class II correction, Smartee S8 technique

Orthodontic treatment with clear aligners has become more complex over the last several years thanks to research conducted by clinicians and their increasing levels of experience, and the introduction of temporary anchorage devices, which improve the predictability of treatment by achieving maximum skeletal anchorage. The present case report describes orthodontic treatment using aligners combined with the use of Class II elastics and extra-alveolar infrazygomatic temporary anchorage devices. Keywords: attachments, Class II, clear aligners, direct temporary anchorage devices, distalisation

Objective: To investigate the vertical changes in incisors and molars that occur following molar distalisation with clear aligners. Methods: A total of 30 patients receiving clear aligner treatment (Invisalign, Align Technology, San Jose, CA, USA) were included in the study. Patients’ digital models were exported from the ClinCheck software (Align Technology) and measured using Geomagic Studio 2014 (Raindrop Geomagic, Research Triangle Park, NC, USA). Various indices regarding characteristics of vertical changes following molar distalisation with clear aligners were measured and compared, including the predicted and achieved molar distalisation, intrusion and change in vertical overlap. A simple linear regression was conducted to examine the impact of distalisation on molar intrusion. Results: The characteristics of spatial changes in molar distalisation with clear aligners were measured, particularly in the vertical dimension. The actual vertical overlap deepened after clear aligner treatment (central incisors 0.43 ± 2.14 mm, lateral incisors 0.79 ± 1.91 mm). Molar intrusion occured (first molar 0.51 ± 0.77 mm, second molar 0.97 ± 0.87 mm), and the difference between the actual and expected molar intrusion was statistically significant. A significant positive correlation was identified between molar distalisation and molar intrusion (P 0.05).In addition, by comparing the different positions of the dental arch, the intrusive effect of molar distalisation was found to be progressively greater from the anterior to the posterior teeth (P 0.05). With the use of temporary anchorage devices, the deepening of vertical overlap and the effects of posterior open bite effects were significantly greater (P 0.05). Conclusions: Molar intrusion is a common occurrence during molar distalisation with clear aligners. It may result in open bite in the molar region and increased vertical overlap in the incisors. The intrusive effect of molar distalisation increases gradually from the anterior to the posterior teeth. Temporary anchorage device–assisted molar distalisation with clear aligners exacerbates open bite in the molar region. Aligner overtreatment of incisor intrusion is recommended if the vertical dimension should be reduced, whereas additional molar extrusion is implemented if the vertical dimension should be maintained or increased for molar distalisation with clear aligners. Keywords: clear aligners, molar distalisation, molar intrusion, temporary anchorage devices, vertical overlap