Evidence map›Paper›PMID 42443707›Full record

ArticleClinical oral investigations2026

Arch width changes following first premolar extractions: a comparison between invisalign and fixed appliances.

Hengyu Hu, Zhaowei Cen, Shuai Huang, Lang Lei

Abstract readComparative Study
PubMed Publisher
In one paragraph

Article in Clinical oral investigations, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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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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3 · Its place in the literature

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0 citing papers in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

4 authors.

Hengyu HuNanjing Stomatological Hospital, Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University, Nanjing, China.
Zhaowei CenNanjing Stomatological Hospital, Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University, Nanjing, China.
Shuai HuangNanjing Stomatological Hospital, Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University, Nanjing, China.
Lang LeiDepartment of Orthodontics, Nanjing Stomatological Hospital,Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University, No. 30, Zhongyang Road, Xuanwu District, Jiangsu, Nanjing, 210008, P.R. China. leilangdental@nju.edu.cn.

Funding

Natural Science Foundation of China No. 82371007
6 · The paper itself

Abstract

objectiveArch width (AW) affects space availability and shifts the anchorage balance in extraction cases. This study aimed to investigate whether AW differs between patients treated with clear aligners (CAs) and those treated with conventional fixed appliances (FAs) following the extraction of four first premolars.

methodsThis retrospective study included 60 Class I patients who underwent extraction of four first premolars and were treated with either CAs (Invisalign, Align Technology) or FAs (MBT prescription, 0.022-inch slot). The CAs group consisted of 3 males and 27 females (mean age, 24.53 ± 4.58 years), and the FAs group included 4 males and 26 females (mean age, 22.60 ± 3.92 years). In the CAs group, patients were instructed to change the aligners every 10 days and to wear them for at least 22 h per day. Digital dental casts and lateral cephalometric radiographs were obtained at the beginning (T1) and completion (T2) of treatment. Maxillary and mandibular intercanine, interpremolar, and intermolar widths were measured. Paired t-tests were used for intragroup comparisons, and independent t-tests were used for intergroup comparisons. Statistical significance was set at P <.05.

resultsMaxillary and mandibular incisors in the CAs group exhibited significantly greater retroclination than those in the FAs group (P <.05). No significant intergroup differences in AW were identified before treatment (P >.05). However, post-treatment measurements demonstrated significantly greater AW in the CAs group at the cusp level of the maxillary and mandibular canines (P <.05). Both groups exhibited statistically significant reductions in maxillary and mandibular interpremolar widths (P <.05), with a more pronounced decrease in the FAs group (P <.05). In the CAs group, intermolar AW remained stable (P >.05), whereas the FAs group showed a significant post-treatment reduction (P <.05). Moreover, following treatment, the achieved AW exceeded the ClinCheck-predicted values at the gingival level of both maxillary and mandibular molars (P <.05).

conclusionsIn extraction cases, patients treated with CAs demonstrated a larger AW and greater lingual inclination of the anterior teeth than those treated with FAs. CLINICAL RELEVANCE: The relatively wider dental arches observed in the CAs group may have implications for space management during treatment. Additionally, the combination of a larger AW and greater incisor retroclination could impose excessive mechanical demands on the flexible aligner trays. Therefore, careful case selection is essential when considering extraction-based treatment with CAs.

Indexed as

BicuspidDental ArchMalocclusion, Angle Class IOrthodontic Appliances, FixedOrthodontic Appliances, RemovableTooth ExtractionAdultCephalometryFemaleHumansMaleOrthodontic Appliance DesignRetrospective StudiesYoung AdultArch widthClear alignersExtraction treatmentFixed appliances

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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.