Actual contribution ratio of maxillary and mandibular molars for total molar relationship correction during maxillary molar sequential distalization using clear aligners with Class II elastics: A finite element analysis

Miniscrew anchorage versus Class II elastics for maxillary arch distalization using clear aligners

OBJECTIVES

To identify whether intramaxillary miniscrew anchorage could achieve a better maxillary arch distalization effect in clear aligner treatment compared to Class II elastics.

MATERIALS AND METHODS

Thirty adult patients with Class II dentition who were treated with whole maxillary arch distalization using clear aligners were collected. Either intramaxillary miniscrew anchorage (miniscrew group, n = 17) or intermaxillary Class II elastics (Class II elastic group, n = 13) were used to support maxillary arch distalization. Three-dimensional predicted and achieved displacements, and angular changes of maxillary posterior teeth and anterior teeth, were measured and compared.

RESULTS

The achieved distalization efficiency was 36.2%-43.9% in the posterior teeth and the retraction efficiency was 36.9%-49.4% in the anterior teeth. No statistically significant differences were found in maxillary arch distalization efficiency between the groups. The miniscrew group achieved less incisor extrusion and posterior tooth distal tipping than the Class II elastic group. Both groups achieved comparable arch expansion, posterior tooth buccal inclination, and anterior tooth lingual inclination.

CONCLUSIONS

Intramaxillary miniscrew anchorage and intermaxillary Class II elastics achieved comparable efficiency in maxillary arch distalization. However, the miniscrew anchorage showed better vertical control in anterior teeth and mesiodistal tipping control in posterior teeth.

Effects of different intrusion patterns during anterior teeth retraction using clear aligners in extraction cases: an iterative finite element analysis

Background

Overtreatment design of clear aligner treatment (CAT) in extraction cases is currently primarily based on the clinical experience of orthodontists and is not supported by robust evidence on the underlying biomechanics. This study aimed to investigate the biomechanical effects of overtreatment strategies involving different maxillary anterior teeth intrusion patterns during anterior teeth retraction by CAT in extraction cases.

Materials and methods

A finite element model of the maxillary dentition with the first premolar extracted was constructed. A loading method of clear aligners (CAs) based on the initial state field was proposed. The iterative method was used to simulate the long-term orthodontic tooth movement under the mechanical load exerted by the CAs. Three groups of CAs were utilized for anterior teeth retraction (G0: control group; G1: incisors intrusion group; G2: anterior teeth intrusion group). Tooth displacement and occlusal plane rotation tendency were analyzed.

Results

In G0, CAT caused lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, mesial tipping, and intrusion of the posterior teeth. In G1, the incisors showed minimal extrusion, whereas the canines showed increased extrusion and distal tipping tendency. G2 showed the smallest degree of posterior occlusal plane angle rotation, while the inclination tendency of the canines and second premolars decreased.

Conclusion

1. In CAT, tooth displacement tendency may change with increased wear time. 2. During anterior teeth retraction, the incisor intrusion pattern can provide effective vertical control for the lateral incisors but has little effect on the central incisors. Anterior teeth intrusion patterns can alleviate the inclination of canines and second premolars, resulting in partial relief of the roller-coaster effect.

Molar distalization in orthodontics: a bibliometric analysis

OBJECTIVES

The study endeavors to undertake a bibliometric analysis on molar distalization, with the objective of illuminating its evolutionary trajectory, current status, and prognosticating future research hotspots and trends.

MATERIAL AND METHODS

A comprehensive exploration of the literature on molar distalization was carried out by conducting a search in the Web of Science (WOS) core database of the University of Hong Kong Electronic Library. The search for topic terms employed included "molar distalization," "molar distalisation," "move molar distally," "molar distal movement," and "molar backwards." The search results were subsequently subjected to meticulous analysis using CiteSpace software. This analysis encompassed various facets such as the citation count; the geographical distribution of the countries, institutions, and journals responsible for publishing the articles; the distribution of the authors; the utilization of keywords within the articles; and the analysis of references.

RESULTS

A total of 516 articles were included in the analysis. The top 5 countries in terms of the number of published papers were the United States (USA), South Korea, Turkey, Italy, and Germany, and the top 5 institutions in terms of the number of published papers were Kyung Hee University, A.T. Still University of Health Sciences, Catholic University of Korea, Seoul St. Mary's Hospital, and Universidade de Sao Paulo. The top 5 authors in terms of the number of published papers were Park, Kook, Bayome, Janson, and Lee. There was little cooperation overall. The top 3 journals in terms of the most published related articles were all orthodontic-related journals. After molar distalization and anchorage, the most frequently used keywords were distalization, movement, and pendulum appliance. Kinzinger GSM is the most frequently cited author in references, and one of his articles also has the highest centrality score in references.

CONCLUSIONS

As the tides of time shift and scholars display an ever-growing dedication to unraveling the intricacies of this therapeutic modality, the realm of molar distalization has undergone notable advancements in technology. Initially, the traditional appliance suffered from aesthetic drawbacks and discomfort. However, contemporary iterations of the appliance have transcended these limitations, boasting enhanced elegance and convenience while concurrently elevating their efficacy. Nevertheless, limitations of current appliances, including their durability and propensity for recurrence post-treatment, continue to necessitate further advancement. Hence, the ongoing scientific inquiry aims to delve deeper into refining treatment modalities and fabricating cutting-edge appliances within this realm.

CLINICAL RELEVANCE

This study holds the potential to significantly enhance the ability of orthodontists to devise treatment protocols and offer state-of-the-art clinical recommendations, thereby empowering them to deliver advanced and refined orthodontic interventions.