Impacts of using orthodontic appliances on the quality of life of children and adolescents: systematic review and meta-analysis

Summary

Background

Although there are previous systematic reviews about the oral health-related quality of life (OHRQoL) impact among children and adolescents after orthodontics treatment, there is no definition for the magnitude of these impacts during the therapy.

Objective

To systematically analyse the literature on changes in the quality of life of children and adolescents during orthodontic treatment.

Limitations

Almost all the studies included in this review are non-randomized clinical trials, which are susceptible to several biases that affect the certainty of evidence obtained, especially by confounding factors and the lack of a control group.

Conclusions and implications

Based on very low certainty of evidence, wearing appliances does not seem to have a significant negative impact during the first year of orthodontic treatment. However, the meta-analytic results suggest that functional limitations in the first 3 months of treatment can be slightly more critical for the impact on the oral health quality of life and consequent patient adherence to treatment.

Funding

This study was financed by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico - Brazil (CNPq), and Fundação de Amparo à Pesquisa do Estado de Minas Gerais – Brazil (FAPEMIG).

Registration

CRD42021234407.

Introduction

When analysing the global prevalence of the need for oral health care, 46% of adolescents require orthodontic treatment (1). Only 25% of children have a normal occlusion during the deciduous dentition and approximately 40% of orthodontic patients seek therapy to treat malocclusions in adolescence, motivated by functional, aesthetic, psychological, or social aspects (2). Furthermore, seeking orthodontic treatment can also be indicated during the general oral health care examination, either because of orofacial pain related to temporomandibular dysfunctions associated with malocclusions (3, 4), dental trauma in children and adolescents with increased overjet or inadequate lip coverage (5), or even sleep problems (6). Moreover, performing orthodontic treatment before the age of 18 may improve the quality of life of patients at the end of treatment (7).

Oral health-related quality of life (OHRQoL) comprises specific domains of overall quality of life, including functional limitations; pain and discomfort; physical, psychological, and social disabilities; and disadvantages due to oral health changes (8). Irrespective of the instrument used to assess OHRQoL, almost all domains are affected negatively at the start of orthodontic treatment (9, 10); however, functional limitations and pain and discomfort caused by orthodontic treatment after initial and follow-up appointments appear to be the most affected ones (11, 12). Patient motivation and professional guidance may favour a linear adaptation to these changes during the treatment (12, 13). Thus, the majority of significant OHRQoL changes appear at the initial treatment phases (14), tending to reduce the impacts as the orthodontic therapy develops (15).

Although there are primary studies about the impact on children and adolescents OHRQoL, its consolidation at a secondary level of scientific evidence is more focussed on the times before (16–20) and after (7, 21, 22) orthodontic treatment, and there is no definition for the magnitude of these impacts during therapy when using appliances. Therefore, this review aimed to systematically analyse the literature to assess the OHRQoL impact in children and adolescents during orthodontic treatment.

Methodology

Protocol registration

The protocol was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) (23) and registered in the International Prospective Register of Systematic Reviews (PROSPERO) database under number CRD42021234407 (http://www.crd.york.ac.uk/PROSPERO). This systematic review was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (24) and conducted according to the Joanna Briggs Institute (JBI) Manual (25).

Research question and eligibility criteria

The review was designed to answer the following question: ‘Does the wearing of appliances impact the quality of life during the orthodontic treatment of children and adolescents?’, following the PICO strategy for structuring, in which: P (population), I (intervention), C (comparison), and O (outcome).

Inclusion criteria

• • Population: children and adolescents up to 19 years old, according to the WHO (26).

• • Intervention: any type of orthodontic treatment.

• • Comparator: OHRQoL before the orthodontic treatment/no use of orthodontic appliances.

• • Outcome: evaluation of OHRQoL.

• • Study design: randomized or non-randomized clinical studies.

There were no restrictions on publication language or year.

Exclusion criteria

• • Studies without data on the quality of life before treatment (baseline).

• • Studies with samples including special needs patients, head and neck radiotherapy and chemotherapy patients, cleft lip patients, systemically compromised patients, and orthosurgical patients.

• • Studies with sample overlapping (in this case, considering the most recent study and that best described the methodology and results).

• • Qualitative studies, case reports, case series, literature reviews, editorials, letters to the editor, personal opinions, books, and book chapters.

Sources of information, search, and selection of studies

The electronic searches were performed in the MedLine (via PubMed), Latin American and Caribbean Health Science Literature (LILACS), SciELO, and EMBASE databases, and Scopus and Web of Science citation databases. The OpenGrey and Open Access Theses and Dissertations (OATD) were used to partially capture the ‘gray literature’. These steps were performed to minimize the selection bias. The MedLine search was constantly updated with electronic alerts, until July 2021. The search descriptors were selected according to the MeSH (Medical Subject Headings), DeCS (Health Sciences Descriptors), and Emtree (Embase Subject Headings) resources. Several combinations among the descriptors were performed with the Boolean operators ‘AND’ and ‘OR’, respecting the syntax rules of each database (Supplementary Table 1).

The results obtained were exported to the EndNote Web™ software (Clarivate™ Analytics, Philadelphia, USA), in which duplicates were removed automatically and the remaining duplicates were removed manually. The remaining results were exported to the Rayyan QCRI (Qatar Computing Research Institute, Doha, Qatar) for the study selection phase. The gray literature was manually analysed, simultaneously and fully, with Microsoft Word™ 2010 (Microsoft™ Ltd, Washington, USA).

Before selecting the studies, two reviewers performed a calibration exercise, in which they discussed the eligibility criteria and applied them to a sample of 20% of the studies retrieved to determine inter-examiner agreement. After reaching an adequate level of agreement (Kappa = 0.93), the selection started.

In the first phase, two reviewers (MTCV and CMM) independently analysed the titles of the studies to assess eligibility. Disagreements between the examiners were discussed and defined by a third examiner (MNO). Titles not related to the topic were eliminated in this phase. In the second phase, the reviewers read the abstracts independently, respecting the eligibility criteria. The results in which titles met the objectives of the study but did not have abstracts available were fully analysed in the subsequent phase. In the third phase, the full texts of the preliminary eligible studies were obtained and evaluated. In case the full texts were not found, a bibliographic request was performed to the library database (COMUT) and an e-mail was sent to the corresponding authors to obtain the texts.

Data collection

Before data extraction, to ensure consistency between the reviewers, a calibration exercise was performed, in which the data from three eligible studies were extracted jointly. After the calibration (Kappa = 0.85), two reviewers (MTCV and CMM) extracted the data from the eligible studies, independently and blinded. In cases of disagreement about the data extraction, a third reviewer (MNO) analysed the conflicts.

The following data were extracted from the articles: study identification (author, year, country, location, and application of ethical criteria), sample characteristics (number of children and/or adolescents, distribution by sex and average age, severity of treatment need or malocclusion, and type of orthodontic appliance used), collection and processing characteristics (questionnaire used, times of questionnaire application, methods of questionnaire application, and type of statistical analysis used), and main results (total scores and scores of each domain of the questionnaires applied before and during treatment, and main outcomes of each study). In case of incomplete or insufficient data, the corresponding authors were contacted via e-mail up to three times, with weekly intervals.

Risk of bias assessment

The risk of bias of the studies selected was assessed with the ‘JBI Critical Appraisal Tools for use in JBI Systematic Reviews—Checklist for Quasi-Experimental Studies’ and the ‘JBI Critical Appraisal Tools for use in JBI Systematic Reviews—Checklist for Randomized Controlled Trials’ (25), according to the specific type of study. Two authors (MTCV and CMM) assessed independently each domain. The risk of bias was categorized as ‘High’ when the study reached up to 49% of ‘yes’ score, ‘Moderate’ when the study reached from 50 to 69% of ‘yes’ score, and ‘Low’ when the study reached over 70% of ‘yes’ score (27). In cases of disagreement, a third reviewer (WAV) analysed the conflicts.

Data synthesis and meta-analysis

The data collected from the studies selected were organized in Microsoft Excel™ 2019 spreadsheets (Microsoft™ Ltd, Washington, USA) and described narratively (qualitative synthesis). The quantitative data synthesis was performed from meta-analyses comparing the mean quality-of-life score before starting orthodontic treatment with the mean score during treatment. The meta-analyses were performed according to five different times of orthodontic treatment: 1. after 1 week; 2. after 1 month; 3. after 3 months; 4. after 6 months; 5. after 12 months from the start of orthodontic treatment. Supplementarily, for each time of orthodontic treatment, meta-analyses were performed according to four different domains: 1. emotional well-being; 2. functional limitations; 3. oral symptoms; 4. social well-being.

Considering that the quality-of-life score was measured for the same individuals at different times, mean differences for paired samples were considered. Different instruments were used to measure the quality of life, therefore, this difference in means was converted to the standardized mean difference (SMD), following Glass’ delta method: $\mathrm{S}\mathrm{M}\mathrm{D}=\frac{M_t-M_0}{\mathrm{D}{\mathrm{P}}_0}$⁠, where M₀ and M_t are the mean quality-of-life score before and at the time t of treatment start, respectively; and SD₀ is the standard deviation of the mean quality-of-life score before starting orthodontic treatment. Positive values indicate an increase in the scores of the negative impact of orthodontic treatment on the quality of life (reduced quality of life) after starting treatment, while negative values indicate a reduction in the scores of the impact of orthodontic treatment (improved quality of life).

The SMD was combined from five meta-analytic models, one for each time, using random effects. The heterogeneity among the studies was measured from three indicators: the I², which indicates the rate of variability caused by heterogeneity among studies; the H², which indicates the level of heterogeneity among studies (H = 1 indicating homogeneity); and the τ², which refers to the variance among studies. All analyses were performed with the Stata 17.0 software (StataCorp LLC, College Station, Texas, USA) at a 5% significance level.

Certainty of evidence

The quality of the evidence and the strength of recommendations were evaluated using the Grade of Recommendation, Assessment, Development, and Evaluation (GRADE) tool. The GRADEpro GDT software (http://gdt.guidelinedevelopment.org) was used to summarize the results. The evaluation was based on the study design, risk of bias, inconsistency, indirect evidence, imprecision, and publication bias. The certainty of evidence would be rated as high, moderate, low, or very low (28).

Results

Study selection

The electronic search identified 2345 results distributed into eight electronic databases, including the ‘gray literature’. After removing the duplicates, 1142 results remained for the analysis. A careful reading of the titles and abstracts excluded 1085 results.

After reading the full texts, 37 studies were excluded (Supplementary Table 2) and 20 studies (14, 15, 29–45) were included in the qualitative analysis. Among them, 11 remained for the meta-analysis (14, 30, 34–38, 41, 43, 44, 46). Figure 1 displays details of the study selection process.

Figure 1.

Flowchart depicting the study selection process (PRISMA flow diagram).

Study characteristics

The studies were published from 2008 to 2020 and conducted in 10 different countries, with two studies in North America (29, 40), six in Europe (30, 32, 34, 44–46), six in Asia (14, 15, 36–39), and six in South America (31, 33, 35, 41–43). Among the 20 eligible studies, only one was a randomized clinical trial (35). The sum of orthodontically treated participants in the eligible studies resulted in 1913 patients. The age group of the eligible studies ranged from 8 to 19 years and female patients composed most of the sample.

Orthodontic treatment need was assessed in different ways. Some studies used the Index of Orthodontic Treatment Need (IOTN) (14, 30, 32, 34, 42, 44, 45), the Dental Aesthetic Index (DAI) (31, 33, 36, 37, 40, 43), the Index of Complexity, Outcome, and Need (ICON) (29), the clinical diagnosis of anterior open bite (AOB) (35), and the patient self-perception of treatment need (38, 39, 41). Moreover, two studies (15, 46) did not report the method used to indicate treatment need.

The fixed orthodontic appliance was the most used in the studies (14, 15, 31, 34, 35, 38–46). Altogether, five different questionnaires were applied [CPQ11–14, OHIP-14, CPQ8–10, OQoLAS11–14, and a specific questionnaire (SQ) developed from previously validated questionnaires]. The questionnaires also varied in application methods. Among the studies presenting this information, most of them chose self-application and the others varied between interviews performed by the orthodontist in charge and online form filling in the SurveyMonkey™ software (SurveyMonkey™, California, USA).

Some of the times of questionnaire application were shared among the studies, besides the baseline: three in the 1st week after starting treatment (14, 38, 39), seven in the 1st month (14, 31, 36, 38, 39, 41, 45), six in the 3rd month (30, 36, 38, 39, 45), eight in the 6th month (29, 31, 34, 36–39, 46), and eight in the 12th month (31–33, 36, 37, 42–44). One study did not specify the time of questionnaire application, only describing it as a follow-up period (40). Table 1 presents the main characteristics of each eligible study.

Table 1:

Main characteristics of eligible studies

Author (country)	Sample (♀, ♂)	Mean age ± SD	Method of assessment treatment need	Questionnaires applied	Method of questionnaires application	Moments of questionnaires application
Zhang et al. (USA) (38)	198 (105♀, 93♂)	13.1 ± 1.5	Self-perceived	CPQ11–14	nr	Baseline, 1 week, 1 month, 3 months, and 6 months
Chen et al. (USA) (39)	222 (148♀, 74♂)	15.7 ± nr	nr	OHIP-14 (Chinese version)	Self-administrated in about 10 min	Baseline, 1 week, 1 month, 3 months, and 6 months
Agou et al. (USA) (40)	118 (59♀, 59♂) T, 74 C, 74	12.9 ± 0.98	DAI	CPQ11–14	Without parent’s help	Baseline and visit with moment not specified
Abreu et al. (UK) (41)	94 (49♀, 45♂)	11.5 ± nr	nr	CPQ11–14	Self-administrated in about 10 min	Baseline and 1 month
Feu et al. (USA) (42)	284 (§ ♀, § ♂) T, 87 (45♀, 47♂) C, 101 (64♀, 60♂) S, 96 (60♀, 42♂)	T, 13.4 ± 1.1 C, 13.7 ± 1.1 S, 13.7 ± 1.2	IOTN (DHC and AC)	OHIP–14	Self-administrated	Baseline, 12 months, and 24 months
Abreu et al. (Germany) (43)	98 (43♀, 45♂)	11.49 ± nr	DAI	CPQ11–14	Self-administrated in about 10 min	Baseline and 12 months
Brosens et al. (UK) (44)	109 (59♀, 50♂)	nr	IOTN (DHC and AC)	CPQ11–14	nr	Baseline and 12 months
Johal et al. (USA) (45)	109 (65♀, 44♂) T, 53 (28♀, 25♂) C, 56 (37♀, 19♂)	13.1 ± 0.91 C, 13.14 ± 0.78 T, 12.91 ± 0.94	IOTN (DHC)	CPQ11–14	nr	Baseline, 1 month, and 3 months
Farzanegan et al. (USA) (46)	148 (97♀, 51♂)	♀, 15.8 ± nr ♂, 16.1 ± nr	nr	Own questionnaire based on adaptations of the CPQ11–14, OHIP, and OIDP	Self-administrated in about 20 min	Baseline, 2 months, and 6 months
Feusier (USA) (29)	59 (32♀, 27♂)	12.6 ± 1.02	ICON	OQoLAS11–14	E-mail	Baseline and 6 months
Al-Jumah (Ireland) (30)	59 (27♀, 32♂)	nr	IOTN (DHC)	CPQ11–14	Software Survey Monkey	Baseline and 3 months
Abreu et al. (Netherlands) (31)	252 (135♀, 117♂) T, 106 (57♀, 49♂) C, 146 (78♀, 68♂)	nr	DAI	CPQ11–14	nr	Baseline, 1 month, 6 months, and 12 months
Jaeken et al. (UK) (32)	324 (174♀, 150♂)	12.6 ± nr	IOTN (DHC and AC)	CPQ11–14	nr	Baseline and 12 months
Miamoto et al. (Brazil) (33)	30 (12♀, 18♂) G1, 15 (4♀, 11♂) G2, 15 (8♀, 7♂)	G1, 9.07 ± 0.79 G2, 9.0 ± 0.84	DAI	CPQ8–10	Self-administrated in about 15 min	Baseline and 12 months
Wang et al. (China) (15)	81 (41♀, 40♂) A, 43 YA, 38	A, 16.1 ± 1.01 YA, 21.5 ± 1.72	nr	OHIP-14 (Chinese version)	Interview	Baseline, 7 months, 16 months, and 21 months
Khraishi (Ireland) (34)	46 (19♀, 27♂)	12.74 ± 0.91	IOTN (DHC and AC)	CPQ11–14	Software Survey Monkey	Baseline and 6 months
Pithon et al. (USA) (35)	80 (42♀, 38♂) T, 40 (21♀, 19♂) C, 40 (21♀, 19♂)	T, 9.0 ± nr C, 8.5 ± nr	Clinic	CPQ8–10	nr	Baseline and 3 months
Baidas et al. (Nigeria) (14)	42 (46♀, 13♂) A, 29 YA, 13	A, 15.0 ± nr YA, 22.0 ± nr	IOTN (DHC)	OHIP-14 (Arabic short version)	Self-administrated in about 10 min	Baseline, first 24 h, 1 week, 2 weeks, and 1 month
Jena et al. (USA) (36)	34 (17♀, 17♂)	16.27 ± 1.4	DAI	OHIP-14 (short-form)	Self-administrated in about 10 min	Baseline, 1 month, 3 months, 6 months, and 12 months
Kassis et al. (France) (37)	60 (46♀, 14♂)	12.0 ± 0.76 ♀, 11.94 ± 0.75 ♂, 12.22 ± 0.22	DAI	CPQ11–14 (Arabian version) and CHQ-CF87	Self-administrated	Baseline, 6 months, 12 months, and 18 months

A, adolescents; AC, aesthetic component; C, control group; DAI, Dental Aesthetic Index; DHC, Dental Health Component; G1, group treated with removable appliances; G2, group treated with bitepads; ICON, Index of Complexity, Outcome, and Need; IOTN, Index of Treatment Need; nr, not related on the study; S, school group; T, treatment group; YA, young adults.

Individual results of the studies

The domains related to oral symptoms and functional limitations showed negative impacts on the quality of life (increased scores) on the first day (14), first week (14, 38, 39), and first month (14, 31, 36, 38, 39, 41, 45) of treatment. These same domains had lower scores (positive impact on the quality of life) from the 3rd month (30, 35, 36, 38, 39, 45), 7th month (29, 31, 34, 36–39, 46), and 12th month (31–33, 36, 37, 42–44). The domains related to psychological, emotional, and social well-being showed divergent scores over time, with periods of stability and minor changes, both positive and negative (Supplementary Table 3).

Risk of individual bias of the studies

In the analysis of the risk of bias of eligible studies with the tool for quasi-experimental studies, 18 studies (14, 15, 29–46) had a low risk of bias and one study (32) a moderate risk. In the analysis of the risk of bias with a tool for randomized clinical trials, one study (35) had a low risk of bias. Table 2 describes further details of the result of the individual risk of bias of the eligible studies.

Table 2:

Risk of bias assessed by the Joanna Briggs Institute Critical Appraisal Tools for use in JBI Critical Appraisal Checklist for Randomized Controlled Trials and for use in JBI Critical Appraisal Checklist for Analytical Quasi-experimental Studies

Author	Q.1	Q.2	Q.3	Q.4	Q.5	Q.6	Q.7	Q.8	Q.9	Q.10	Q.11	Q.12	Q.13	% yes/risk
Randomized controlled trial
Pithon et al. (35)	√	√	√	—	—	√	√	√	√	√	√	√	√	84.6/low
Quasi-experimental studies
Zhang et al. (38)	√	√	√	—	√	U	√	√	√	*	*	*	*	77.8/Low
Chen et al. (39)	√	√	√	—	√	√	√	√	√	*	*	*	*	88.9/low
Agou et al. (40)	√	U	√	√	—	√	√	√	√	*	*	*	*	77.8/low
Abreu et al. (41)	√	√	√	—	—	√	√	√	√	*	*	*	*	77.8/low
Feu et al. (42)	√	√	√	√	√	√	√	√	√	*	*	*	*	100/low
Abreu et al. (43)	√	√	√	—	—	√	√	√	√	*	*	*	*	77.8/low
Brosens et al. (44)	√	√	√	—	—	√	√	√	√	*	*	*	*	77.8/low
Johal et al. (45)	√	U	√	√	√	√	√	√	√	*	*	*	*	88.9/low
Farzanegan et al. (46)	√	√	√	—	√	U	√	√	√	*	*	*	*	77.8/low
Feusier (29)	√	√	√	—	—	√	√	√	√	*	*	*	*	77.8/low
Al-Jumah (30)	√	√	√	—	—	√	√	√	√	*	*	*	*	77.8/low
Abreu et al. (31)	√	√	√	√	√	√	√	√	√	*	*	*	*	100/low
Jaeken et al. (32)	√	√	√	—	—	—	√	√	√	*	*	*	*	66.7/moderate
Miamoto et al. (33)	√	√	√	—	—	√	√	√	√	*	*	*	*	77.8/low
Wang et al. (15)	√	√	√	—	√	√	√	√	√	*	*	*	*	88.9/low
Khraishi (34)	√	√	√	—	√	√	√	√	√	*	*	*	*	88.9/low
Baidas et al. (14)	√	√	√	—	√	√	√	√	√	*	*	*	*	88.9/low
Jena et al. (36)	√	√	√	—	√	√	√	√	√	*	*	*	*	88.9/low
Kassis et al. (37)	√	√	√	—	√	√	√	√	√	*	*	*	*	88.9/low

√, yes; —, no; U, unclear; NA, not applicable; *, not related to the study.

Data synthesis and meta-analysis

The mean and standard deviation were collected from the overall score and the scores of each domain of the different questionnaires applied in the eligible studies. Supplementary Table 4 summarizes these quantitative data.

Only two studies provided sufficient information and were eligible for the meta-analysis that assessed the changes in the quality-of-life score 1 week after starting orthodontic treatment. The scores 1 week after starting treatment were statistically similar [SMD = 0.19; 95% confidence interval (CI) = −2.18; 2.55; P = 0.88] to the quality-of-life score before starting treatment (Figure 2). Likewise, there were no differences between the quality-of-life scores before and 1 month after starting orthodontic treatment (SMD = 0.42; 95% CI = −0.90; 1.74; P = 0.53) (Figure 3). According to the specific meta-analyses of each domain after 1 month of treatment, only the functional limitations domain showed significant negative impacts when compared with baseline (Supplementary Table 5).

Figure 2.

Meta-analysis assessing the changes in the quality-of-life scores 1 week after starting orthodontic treatment.

Figure 3.

Meta-analysis assessing the changes in the quality-of-life scores 1 month after starting orthodontic treatment.

In the analysis of the four studies that assessed the quality-of-life scores 3 months after starting orthodontic treatment, the SMD was zero (95% CI = −0.61; 0.61) (Figure 4). According to the specific meta-analyses of each domain after 3 months of treatment, only the functional limitations domain showed significant negative impacts when compared with baseline; while the emotional well-being showed significant positive impacts compared with baseline (Supplementary Table 5).

Figure 4.

Meta-analysis assessing the changes in the quality-of-life scores 3 months after starting orthodontic treatment.

The quality-of-life scores 6 and 12 months after starting orthodontic treatment were, respectively, −0.08 (95% CI = −1.37; 1.22) and −0.49 (95% CI = −1.54; 0.57). However, none of the analyses showed evidence of statistically significant differences (both P values >0.05) (Figures 5 and 6). No domain showed a significant impact when compared with baseline for either 6 or 12 months.

Figure 5.

Meta-analysis assessing the changes in the quality-of-life scores 6 months after starting orthodontic treatment.

Figure 6.

Meta-analysis assessing the changes in the quality-of-life scores 1 year after starting orthodontic treatment.

Certainty of evidence

The certainty of evidence was analysed according to the time of quality-of-life assessment (1 week and 1, 3, 6, and 12 months). In all analyses, the evidence came almost entirely from non-randomized studies, therefore starting the assessment with low certainty. Moreover, the certainty of evidence was downgraded because of the imprecision of estimates (Table 3). Thus, all outcomes presented very low certainty of evidence.

Table 3:

Summary of findings by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) for the outcomes of the systematic review and meta-analysis

Certainty assessment						Effect	Certainty
Number of studies	Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations	Relative SMD (95% CI)
OHRQoL—baseline versus 1 week
Two non-randomized studies	Not serious	Not serious	Not serious	Serious*	None**	0.19 (−2.18 to 2.55)	㊉ Very low
OHRQoL—baseline versus 1 month
Four non-randomized studies	Not serious	Not serious	Not serious	Serious*	None**	0.42 (−0.90 to 1.74)	㊉ Very low
OHRQoL—baseline versus 3 months
Four non-randomized studies	Not serious	Not serious	Not serious	Serious*	None**	0.00 (−0.61 to 0.61)	㊉ Very low
OHRQoL—baseline versus 6 months
Five non-randomized studies	Not serious	Not serious	Not serious	Serious*	None**	−0.08 (−0.37 to 1.22)	㊉ Very low
OHRQoL—baseline versus 12 months
Four non-randomized studies	Not serious	Not serious	Not serious	Serious*	None**	−0.49 (−1.54 to 0.54)	㊉ Very low

CI, confidence interval; OHRQoL, oral health-related quality of life; OR, odds ratio.

GRADE Working Group grades of evidence.

High certainty: very confident that the true effect is close to the estimated effect.

Moderate certainty: moderately confident in the effect estimated: the true effect is likely close to the estimated effect but it may be substantially different.

Low certainty: the confidence in the effect estimated is limited: the true effect may be substantially different from the estimated effect.

Very low certainty: very little confidence in the effect estimated: the true effect may be substantially different from the estimated effect.

*Confidence interval suggests no association in one end and important association in the other—downgraded by one level.

^**Publication bias was not assessed due to the low number of studies.

Discussion

The present systematic review and meta-analysis aimed to analyse the impacts on the OHRQoL of children and adolescents during orthodontic treatment. The evidence of the 20 studies selected for the qualitative synthesis explained that OHRQoL changes throughout orthodontic therapy. However, from the analysis of the studies that met the criteria for the final meta-analysis, these changes were not different when compared with the orthodontic treatment baseline.

Negative impacts on the domains related to oral symptoms and functional limitations were identified in most eligible studies, especially on the first day (14), first week (14, 38, 39), and first month (14, 31, 36, 38, 39, 41, 45) of orthodontic treatment. These data agreed with previous studies reporting significant changes after initial appointments, as follows: pain and discomfort (11–13, 47); gingival hyperplasia, erythema, and bleeding (13, 48); oral hygiene problems (13, 48); diction problems (12, 13, 48); and chewing problems (12, 13). These results may have affected the overall scores of the studies and help explain the data obtained in the meta-analyses of the first and third months of treatment, which shows directions of effect indicating negative impacts on the quality of life of patients.

However, after 6 months of treatment, the scores decreased (lower impact on quality of life) for these domains (oral symptoms and functional limitations) in most eligible studies, which can be justified by an adaptation of patients to the orthodontic treatment, from pain sensitivity to the adequacy of daily routine habits for improved comfort. The meta-analysis also indicated an inversion of the direction of effect from the 6th and 12th months after treatment start, when the scores of treatment impact on the quality of life decreased compared with the baseline.

Studies that reported the provision of more complete instructions to patients about specific oral hygiene, recommended diet, experience of initial pain, or use of palliative medication for mucosal irritation associated with trauma due to the use of appliances (31, 41, 43) revealed less significant impacts on OHRQoL. This finding highlights the importance of a good professional–patient relationship and the improvement of professionals to better instruct patients about the potential effects and care required during the treatment.

However, the variation in times of stability and changes of the domains related to psychological, emotional, and social well-being could be explained by the individuality of each patient, reflected by anxiety, shame, self-esteem, self-concept, and relaxation difficulties (12, 49). Moreover, each age group faces specific sociocultural challenges in their families, groups of friends, and schools, which may affect the mind and behaviour of patients regarding orthodontic treatment. Some studies reported that emotional well-being can be a protective factor for the negative impacts from this treatment, thus lower scores of this domain were associated with less negative impacts (32, 37, 44).

The balance between negative impact related to oral symptoms and functional limitations and positive impact related to psychological, emotional, and social well-being helps explain the lack of significant differences in the overall scores obtained in the present meta-analysis. Especially regarding orthodontic treatment, it can be assumed that despite the functional limitations imposed by the orthodontic appliance, the psychological and emotional well-being of undergoing treatment and the benefits it will provide to patients are sufficient to counterbalance the negative effects. These results show the importance of an overall analysis of patients and how the quality of life can be affected by several factors.

Potential limitations can be established on the selected studies. First, the recall bias in the application of questionnaires, considering that their questions refer to the last 3 months of the life of participants, making data collection dependent on subjective memories. Furthermore, the inclusion criteria of this systematic review were quite wide, resulting in a large range of different experimental designs that may have influenced divergences in individual results, especially regarding the several tools applied for the measurement of OHRQoL and the types of orthodontic appliances, because fixed and functional appliances may affect OHRQoL more negatively, especially by the subjective experience of pain and discomfort and oral symptoms and functional limitations (32, 34, 39, 41, 44), while removable appliances may promote more discrete functional limitations during their use, such as speech problems (34, 50). The degrees of malocclusion severity and their assessment methods may also represent relevant factors because severe degrees of malocclusion can be related to higher impacts on OHRQoL (20) and the assessment methods diverged between subjective (patient self-perception of treatment need) and objective (IOTN, DAI, ICON, and AOB). Furthermore, almost all the studies included in this review are non-randomized clinical trials, which are susceptible to several biases that affect the certainty of evidence obtained, especially by confounding factors and the lack of a control group. Further studies with the application of well-planned and more standardized methodologies are encouraged to fill these gaps.

Other aspects might have influenced participants’ perception of quality of life, such as their age range (8–19 years) and socioeconomic status. It is expected that adolescents may feel more affected than children (51), given their aesthetic consciousness level. Additionally, in some countries, orthodontic appliances can be considered a symbol of increased social status (52), and for children and adolescents of a low social class, this may overcome the pain and discomfort caused by such a treatment. Finally, aspects related to the individuals’ psychological, emotional, and training facets might have affected their perception of life (40, 48, 53, 54). However, these aspects are yet to be further investigated in future studies.

Nevertheless, this study presents strengths that deserve to be highlighted. First, it is an original systematic review with an extensive search strategy, which included databases from the gray literature, thus reducing the risk of selection and publication biases. Additionally, this review may help professionals to understand the perception of patients during orthodontic treatment and their main needs, such as oral symptoms related to the use of appliances and negative impacts during their daily routine. Furthermore, it was possible to analyse the negative impacts in each domain in specific periods during treatment, which can help professionals identify the most critical periods of patient compliance to treatment.

Conclusion

Based on very low certainty of evidence, wearing appliances does not seem to have a significant negative impact during the first year of orthodontic treatment. However, the meta-analytic results suggest that functional limitations in the first 3 months of treatment can be slightly more critical for the impact on the oral health quality of life and consequent patient adherence to treatment. Thus, it is suggested that throughout the treatment, orthodontists should reinforce to the patients the importance and benefits of the orthodontic appliance for their health, despite the negative impacts during its use.

Funding

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) - Finance Code 001. We are also thankful for the support from Conselho Nacional de Desenvolvimento Científico e Tecnológico - Brazil (CNPq) and Fundação de Amparo à Pesquisa do Estado de Minas Gerais – Brazil (FAPEMIG).

Conflicts of interest

None to declare.

Data availability

The data underlying this article will be shared on reasonable request to the corresponding author.