Evidence map›Paper›PMID 40604683›Full record

ArticleBMC oral health2025

Biomechanical effects of clear aligners with different distal coverage designs combined with Class II elastic traction for maxillary first molar distalization: a finite element study.

Yiyan Zhang, Peiyan Wang, Chunmiao Jiang, Yi Liu, Xiangyu Ma, Yang Liu, Cunhui Fan

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In one paragraph

Article in BMC oral health, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 4 papers, 1 of them a synthesis that pooled it.

0numbers the graph read from it
0cells of the map it votes in
4citing papers in PubMed, 1 pooled it
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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

4 citing papers in PubMed, 1 synthesis or guideline pooled it.

  1. [Advancements in biomechanics and orthodontic strategies for clear aligner therapy].Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology · 2026
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4 · The record

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5 · Who and what money

Authors and funding

7 authors.

Yiyan ZhangDepartment of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China.
Peiyan WangSchool of Stomatology, Qingdao University, Qingdao, 266023, China.
Chunmiao JiangDepartment of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China.
Yi LiuSchool of Stomatology, Qingdao University, Qingdao, 266023, China.
Xiangyu MaDepartment of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China.
Yang LiuDepartment of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China. dianaliuyang@qdu.edu.cn.
Cunhui FanDepartment of Orthodontics, The Affiliated Hospital of Qingdao University, Qingdao, 266003, China. kysfch@126.com.

Funding

China Oral Health Foundation A2023-023National Natural Science Foundation of China 82001086
6 · The paper itself

Abstract

backgroundThe sequential distalization of teeth may affect the final efficacy of molar distalization in clear aligner treatment (CAT), necessitating additional anchorage protection for distalized posterior teeth. This study aimed to examine the anchorage protection effects of a distal uncoverage clear aligner (DUCA) and Class II elastic traction on the distalized second molar during maxillary first molar distalization. MATERIALS AND

methodsFinite element models of maxillary first molar distalization in CAT were constructed. Two different designs of CAs-a distal coverage aligner (DCA) and a DUCA-were utilized for maxillary first molar distalization after the second molar had been distalized by 2 mm. The force value of Class II elastic traction was set to 0, 1, 2, and 3 N. The displacement of the maxillary teeth and CAs was recorded.

resultsSignificant biomechanical differences were observed between DCA and DUCA. The initial closure of the space between the first and second molars in the DUCA group was mostly due to the first molar distalization. In comparison to DCA, DUCA exhibited less mesial displacement of the second molar and greater anterior anchorage loss. The anchorage loss reduction of the canines caused by Class II traction was the most pronounced, whereas the impact on the second molar was minimal.

conclusionDuring first molar distalization in CAT, the anchorage protection effect of Class II elastic traction on the distalized second molar was limited. The utilization of a DUCA can effectively mitigate anchorage loss of second molar. Simultaneously, it is crucial to apply a greater Class II traction force to protect the anterior anchorage.

Indexed as

Finite Element AnalysisMolarOrthodontic Appliance DesignOrthodontic Appliances, RemovableTooth Movement TechniquesBiomechanical PhenomenaHumansMaxillaOrthodontic Anchorage ProceduresClass II elasticsClear alignerFinite element analysisMolar distalization

Identifiers

PMID40604683
PMCPMC12224743

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.