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Abstract

Objective

The aim was to evaluate the efficiency of customized orthodontic appliances, developed using patient-specific anatomical data, compared to conventional fixed appliances.

Materials and Methods

Electronic databases such as PubMed, ScienceDirect, LILACS, Cochrane Trials, German National Library of Medicine, and OpenGrey were searched for relevant articles without any restrictions on publication date or language. After removing duplicates, articles were screened based on the pre-established eligibility criteria using the PICOS (participants, intervention, comparison, outcomes, study design) framework. Risk of bias and quality of evidence were evaluated, and a random-effects meta-analysis with a 95% confidence interval was conducted.

Results

Nine studies (three randomized controlled trials and six observational studies) met the inclusion criteria. Four of them studied labial customized appliances, while five studies were on lingual customized appliances. The meta-analysis found that customized appliances significantly reduced treatment duration (−3.91 months, P = .02) compared to conventional systems, although heterogeneity was high (I² = 88%). There were no significant differences in the American Board of Orthodontics-Discrepancy Index (ABO-DI) or cast-radiograph evaluation (ABO-CRE) scores. The overall risk of bias was moderate, and the certainty of evidence ranged from low to moderate. Narrative synthesis was carried out for peer assessment rating scores, emergency visits, patient discomfort, and speech difficulties. Sensitivity analyses were performed to assess the robustness of pooled estimates. Subgroup analyses showed a more pronounced treatment duration benefit in labial customized appliances, while lingual customized appliances showed more patient-reported issues.

Conclusion

Customized orthodontic systems significantly shorten treatment time compared to conventional systems; however, this should be interpreted with caution due to high heterogeneity. No significant difference was noted in clinical outcomes (ABO-DI and ABO-CR scores). While faster treatment is the primary benefit, factors such as cost, discomfort, and planning time need to be assessed in future trials. Further research on cost-effectiveness and long-term stability is needed to guide clinical decisions.

Keywords

Customized conventional orthodontics appliances

Introduction

Fixed orthodontic therapy to correct malocclusion was introduced almost a hundred years ago by Angle in 1925 with the Edgewise appliance, which was subsequently modified by Andrews, incorporating first-, second-, and third-order movements within the bracket. This modification served as the basis of the pre-adjusted edgewise appliance (PEA) as we know it.¹

Different prescriptions and bracket designs were developed over the years to improve treatment efficiency.² Despite these advancements, finishing requires wire bending to complete treatment due to variations in tooth morphology and inaccuracies in bracket placement. This not only increases total treatment duration, but also decreases treatment efficiency.

To reduce human error during bracket placement, indirect bonding was introduced by Silverman et al. in 1972.³ However, a recent systematic review by Patano et al. revealed that even though it minimizes bracket placement errors, it still takes a longer time to complete than traditional methods.⁴ Customization in brackets, wires, aligners, and various orthodontic appliances is now more feasible due to technological advancements like digital intraoral scanning, computer-aided design (CAD), 3D printing, and artificial intelligence.^{5, 6} Patients treated with a customized CAD/computer-aided manufacturing (CAM) orthodontic system showed fewer archwire appointments, shorter overall treatment time, and lower American Board of Orthodontics (ABO) scores.⁷ However, systematic reviews on the comparison between customized and non-customized orthodontic appliances have been limited. Ke et al. systematically reviewed the treatment effectiveness between aligners and fixed appliances.⁸ They found that aligners showed segmented movement of teeth and shortened treatment duration, but they were not as effective in producing adequate occlusal contacts, controlling tooth torque, and retention. Customized retainers fabricated via CAD/CAM showed a lower plaque index than conventional retainers.⁹

Currently, customized fixed orthodontic appliances are fabricated in the office using CAD/CAM; commercially available, such as the Insignia™ (Ormco, Calif), and Incognito (3M Unitek, Bad Essen, Germany).^10–12 Orthodontists can adopt customized systems to begin treatment with the final goal in mind and streamline mechanics to reach the best possible outcome. In the coming years, technological advancements such as artificial intelligence will be able to aid in making customization simpler and more accessible for orthodontists. Yassir et al. conducted a systematic review limited to prospective studies, which may have excluded relevant data from high-quality retrospective research.¹³ To address this gap, the present review includes a broader range of study designs, including randomized, prospective, and retrospective cohort studies, to provide a more comprehensive evaluation of the available evidence on the treatment efficiency and clinical outcomes of customized fixed appliances. The review question guiding this systematic review was “Do customized fixed orthodontic appliances (labial or lingual) improve treatment efficiency or clinical outcomes compared to conventional fixed orthodontic appliances in adolescent and adult patients?”

Materials and Methods

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines 2020 were followed for conducting this systematic review and meta-analysis.¹⁴ The study protocol was registered with PROSPERO (International Prospective Registry of Systematic Reviews) with registration number CRD42022309855.

Eligibility Criteria

The PICOS (participants, intervention, comparison, outcomes, study design) framework was used to establish eligibility criteria (Appendix A). Both randomized and non-randomized studies comparing malocclusion treatment in orthodontic patients using customized versus conventional fixed appliances were included. Studies involving adjunct treatments like skeletal anchorage, extraoral traction, low-level laser therapy, pharmacological interventions, or supplemental vibration were excluded.

The primary aim of this study was to evaluate the efficacy of customized fixed appliances based on treatment duration, while secondary outcomes included clinical performance indicators (American Board of Orthodontics-Discrepancy Index (ABO-DI), American Board of Orthodontics-cast-radiograph evaluation (ABO-CRE), peer assessment rating (PAR)), treatment mechanics (e.g., bracket loss, number of visits), and patient-centered factors (e.g., comfort, speech, mastication), in comparison to conventional fixed appliances.

Search Strategy

Electronic databases, including PubMed, ScienceDirect, LILACS, Cochrane Trials, German National Library of Medicine, and OpenGrey, were searched for relevant articles without restrictions on publication date or language. The search strategy combined Medical Subject Headings (MeSH) and common terms such as “malocclusion OR dental alignment,” “orthodontic appliance design,” “orthodontics, corrective/instrumentation or methods,” “Custom* or computer-aided design or image processing,” and “treatment outcome or clinical efficacy.” Appendix B details the search sequence for each database. Manual cross-referencing was also conducted to identify any missed studies.

Screening and Selection of Papers

Articles from all sources were uploaded to the Rayyan QCRI application.¹⁵ Two independent reviewers (SV and GM) removed duplicates and screened articles based on eligibility criteria. Full-text assessments were conducted for final inclusion. In the case of disagreement, the final reviewer (PC) was consulted, and resolutions were guided by the Cochrane Handbook for Systematic Reviews of Interventions.¹⁶

Data Collection, Items, and Processing

Two reviewers (SV and NKD) independently extracted data using predesigned forms covering study design, patient characteristics, interventions, controls, total number of patients, mean age, treatment duration, measured parameters, statistical tests, and results. They recorded data, cross-checked entries, and resolved discrepancies with the final reviewer (PC). For studies with missing information, attempts were made to retrieve data through email correspondence with authors. If unsuccessful, estimation methods from the Cochrane Handbook for Systematic Reviews of Interventions were used.¹⁶

Assessment of Quality and Risk of Bias (RoB) of Included Studies

Cochrane guidelines were used to evaluate the RoB in the included studies, using the ROBINS-I tool for non-randomized studies and the RoB 2 tool for randomized trials.^{17, 18} Two reviewers (SV and NKJ) conducted the assessment independently, resolving disagreements with the final reviewer (PC).

The ROBINS-I tool assessed bias across seven domains, rating each as “Low,” “Moderate,” “Serious,” “Critical,” or “No Information.” An overall RoB judgment was made after domain assessments.¹⁷ For RoB 2, bias was rated in five domains as “Low,” “Some Concerns,” or “High,” with overall risk determined accordingly.¹⁸

Summary Measures and Data Synthesis

The following details were recorded and evaluated based on the outcomes of the included studies: treatment duration, ABO index, PAR index, and differences in oral comfort, speech, mastication, and hygiene. Means and standard deviations were noted; if values were not reported, they were calculated per Cochrane guidelines or obtained from the authors. A random-effects model was used for the meta-analysis to account for heterogeneity in patient characteristics, interventions, and study designs.¹⁹ Heterogeneity was assessed using forest plots, the Cochrane Q test, and I² statistics.²⁰I² values of 0%-40% indicated minimal heterogeneity, 40%-60% moderate, 60%-90% substantial, and 90%-100% considerable. Publication bias was examined with funnel plots.^{21, 22}

Certainty Assessment

GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) tool was used to evaluate the quality of evidence for each primary outcome variable via GRADEpro (https://gradepro.org/).²³ Evidence profiles and summary tables were created for each outcome, assessing domains like RoB, indirectness, inconsistency, imprecision, and publication bias. Outcomes were graded as high, moderate, low, or very low quality based on the GRADE criteria.

Results

Study Selection (Figure 1)

Figure 1 shows the PRISMA flow diagram for the study screening process. A total of 1,289 records were identified from databases like PubMed, ScienceDirect, LILACS, Cochrane Trials, German National Library of Medicine, and OpenGrey, and uploaded to Rayyan QCRI. After removing 67 duplicates, 1,222 studies were screened based on predefined eligibility criteria. Full-text assessment of 12 studies led to the exclusion of 3, with 9 included in the final analysis. Reasons for exclusion are detailed in Figure 1.

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Flow Diagram.

Study Characteristics

Study design, characteristics of patients, intervention, control, total number of patients, mean age (in years) of the sample, total treatment duration, parameters measured, statistical tests, and results of the included studies are presented in Table 1. Among the nine studies, six were observational cohort studies (three prospective, three retrospective), and three were randomized controlled trials (RCTs).^{7, 24–31}

Table 1.

Characteristics of the Studies Included in the Systematic Review.

Author, Year	Study Design	Country	Appliance Type (Custom)—EG	Appliance Type (Conventional)—CG	Sample Size (M/F)	Age (Mean ± SD)	Treatment Duration (Months)	Outcomes Measured	RoB Tool	RoB Judgment
Ata-Ali et al.,²⁴ 2020	Retrospective cohort	Spain	Lingual (Incognito)	Victory series™ 0.01800 slot (3M Unitek, Monrovia, CA, USA)	72 (57/15)	EG: 28.6 ± 6.7, CG: 26.6 ± 9.5	EG: 33.4, CG: 29.2	ABO-DI, ABO-CR	ROBINS-I	Moderate
Brown et al.,²⁵ 2015	Retrospective cohort	USA	Labial (Insignia)	Damon Q (Ormco, Orange, CA)	96 (47/49)	EG: 13.42, CG: 13.92	EG: 14.1, CG: ~16-17	ABO-DI, ABO-CR, appointments	ROBINS-I	Some concerns
Weber et al.,⁷ 2013	Retrospective cohort	USA	Labial (Insignia)	Modified Roth, Titanium Orthos	46 (23/23)	EG: 27.85 ± 12.3, CG: 19.77 ± 14.4	EG: 14.2, CG: 22.9	PAR index, ABO, appointments	ROBINS-I	Low
Wu et al.,²⁶ 2011	Prospective cohort	Hong Kong	Lingual (Incognito)	Mini Diamond (Ormco, Glendora, CA)	60 (22/38)	EG: 21.6 ± 2.24, CG: 20.3 ± 4.21	NR	Oral comfort, speech, mastication	ROBINS-I	Low
Stamm et al.,²⁷ 2005	Prospective cohort	Germany	Lingual (Incognito)	Ormco^® seventh generation	42	EG and CG: 27.1 ± 12.2	NR	Speech, oral hygiene, discomfort	ROBINS-I	Moderate
Jackers et al.,²⁹ 2020	Prospective cohort	Belgium	Labial (Insignia)	Damon Q, Ormco, CA	24 (7/17)	EG: 26.6 ± 7.0, CG: 20.1 ± 4.6	EG: 13.1, CG: 16.6	ABO-DI, ABO-CR	ROBINS-I	Some concerns
Hegele et al.,³⁰ 2021	Quasi-RCT	Germany	Labial (Insignia)	Damon™ brackets (Ormco)	38 (15/23)	EG and CG: 14.3	EG: 16.7, CG: 16.8	ABO-CR, appointments, wire bends	RoB 2	Some concerns
Penning et al.,³¹ 2017	RCT	Netherlands	Labial (Insignia)	Damon Q, Ormco, CA	180 (77/103)	EG: 14.55 ± 4.11, CG: 13.66 ± 1.34	EG: 15.5, CG: 14.9	PAR score, appointments, complaints	RoB 2	Some concerns
Kaptaç et al.,²⁸ 2021	RCT	Turkey	Lingual (Incognito)	Gemini labial brackets (3M Unitek, Monrovia, CA, USA)	20 (5/15)	EG and CG: 27.1 ± 12.2	NR	Irregularity index, arch parameters	RoB 2	Some concerns

Note: ABO-CR, American Board of Orthodontics-cast-radiograph; ABO-DI, American Board of Orthodontics-Discrepancy Index; CG, control group; EG, experimental group; PAR, peer assessment rating; RCT, randomized controlled trial; RoB 2, risk of bias 2; ROBINS-I, risk of bias in non-randomized studies—of interventions; SD, standard deviation; NR, not reported.

Conventional fixed orthodontic appliances were McLaughlin, Bennet, and Trevisi (MBT), Damon self-ligating appliances were most frequently used, whereas Incognito (lingual) and Insignia (labial) systems were the most commonly used customized fixed PEAs. The total number of patients varied amongst the studies from 20 to 180, with a mean age of 13-27 years, irrespective of sex.

Most studies evaluated ABO and treatment duration, whereas two studies evaluated oral discomfort, mastication, speech disturbances, and social pressure. Primary studies by Hegele et al.³⁰ and Penning et al.³¹ evaluated the number of lost or repositioned brackets, archwire bends, visits, and complaints, along with a little irregularity index. Kaptaç et al. measured the irregularity index, and it was the only study that measured intermolar width, intercanine width, and arch length between customized and conventional fixed orthodontic appliances.²⁸ PAR score was measured by Penning et al.³¹ and Weber et al.⁷ to evaluate orthodontic treatment quality. Detailed narrative synthesis of secondary outcomes, such as PAR scores, speech, oral discomfort, mastication, and emergency visits, is presented in Table 2.

Table 2.

Narrative Synthesis Table for Non-pooled Secondary Outcomes.

Outcome Domain	Study (Author, Year)	Customized Appliance Outcome	Conventional Appliance Outcome	Notes/Comments
Speech difficulties	Wu et al.,²⁶ 2011	More speech difficulty initially	Less difficulty	Lingual appliances caused early adaptation issues
Speech difficulties	Stamm et al.,²⁷ 2005	Mild-moderate speech impairment initially	Minimal speech disruption	Lingual design impacted speech clarity
Patient comfort/discomfort	Wu et al.,²⁶ 2011	Lower comfort in the initial phase	Higher comfort initially	Lingual brackets affected the tongue space
Patient comfort/discomfort	Penning et al.,³¹ 2017	Fewer patient complaints	More discomfort reported	Patient-reported outcomes varied
Mastication	Wu et al.,²⁶ 2011	Some difficulty was noted initially	Better chewing efficiency early on	Resolved over time
Oral hygiene	Stamm et al.,²⁷ 2005	More difficult with lingual appliances	Easier hygiene maintenance	Related to appliance position
Appointments/emergency visits	Brown et al.,²⁵ 2015	Fewer appointments overall	More emergency visits and longer follow-ups	Insignia improved efficiency
	Weber et al.,⁷ 2013	Shorter clinical time	More visits, more adjustments	Custom wire bends reduced the need for chairside work
	Hegele et al.,³⁰ 2021	Fewer wire bends, comparable number of visits	More adjustments needed	Precision bracket positioning improved workflow
	Penning et al.,³¹ 2017	Slight reduction in visits and complaints	More complaints reported	Not all differences statistically significant
Treatment outcome (ABO, PAR)	Ata-Ali et al.,²⁴ 2020	Lower ABO-DI and better finishing scores	Higher ABO-DI	Lingual Incognito group showed more accuracy
	Brown et al.,²⁵ 2015	Better ABO scores	Moderate results	Also showed fewer visits
	Weber et al.,⁷ 2013	Similar PAR and ABO improvements	Longer treatment duration	Outcomes broadly comparable
	Jackers et al.,²⁹ 2020	Slightly better ABO-DI and CR	Acceptable results	Small sample size
	Penning et al.,³¹ 2017	Similar PAR improvements	Comparable	Randomized design supported findings
Arch parameters/irregularity index	Kaptaç et al.,²⁸ 2021	Better anterior alignment, arch coordination	Wider arch forms, less precision	Small RCT, limited follow-up

Note: ABO-CR, American Board of Orthodontics-cast-radiograph; ABO-DI, American Board of Orthodontics-Discrepancy Index; PAR, peer assessment rating; RCT, randomized controlled trial.

RoB in Studies (Figures 2 and 3)

The ROBINS-I tool was used to assess the RoB in six non-randomized studies,^{7, 24–27, 29} and the RoB 2 tool was applied to three randomized trials.^{28, 30, 31} For ROBINS-I, two studies had moderate concerns in domain 1,^{25, 27} while the other domains showed low bias. Out of the six studies,^{7, 24–27, 29} only two had moderate concerns, as shown in Figure 2.^{25, 27} For RoB 2, all domains except domain 2 had a low RoB, with domain 2 showing some concerns in all three studies.^{28, 30, 31} Overall, the RoB was judged with some concerns, as shown in Figure 3.

Figure 2.

ROBINS-I (Risk of Bias in Non-randomized Studies—of Interventions) of Included Studies.

Figure 3.

RoB 2 (Risk of Bias 2) of Included Studies.

Results of Meta Analysis (Figure 4)

Treatment Duration (Figure 4a)

Comparison of treatment duration between customized PEA and conventional PEA is depicted in Figure 4a. The pooled mean difference in treatment duration was −3.91 months (95% CI: −7.06 to −0.76), indicating that customized PEA was associated with shorter treatment periods compared to non-customized PEA. However, considerable heterogeneity was seen among the included studies, with an I² value of 88%, implying high variability in the results. Despite this heterogeneity, the overall effect was deemed to be statistically significant (P = .02), indicating that the shorter treatment duration associated with customized PEA is unlikely to be due to chance.

Figure 4.

Results of Meta-analysis. (a) Treatment Duration. (b) American Board of Orthodontics-Discrepancy Index (ABO-DI) and (c) American Board of Orthodontics-cast-radiograph (ABO-CR).

ABO-DI (Figure 4b)

ABO-DI between customized PEAs and non-customized PEA revealed no significant differences between the two treatment approaches, as seen in Figure 4b (P = .82). The pooled mean difference was 0.24 (95% CI: −1.81 to 2.30), indicating a slight but statistically insignificant trend favoring customized PEA. The heterogeneity among studies was negligible, with an I² value of 0%, suggesting that the results across studies were consistent.

ABO-CR (Figure 4c)

The ABO-CR scores between customized and non-customized PEAs showed no significant differences, as seen in Figure 4c. A slight trend toward better scores with customized PEA was observed with a pooled mean difference of −1.75 (95% CI: −5.40 to 1.91). Despite moderate heterogeneity in the studies (I² = 60%), the difference in ABO-CR scores was not statistically significant (P value = .35).

Analysis of the Certainty of the Evidence

The certainty of evidence was assessed using the GRADE framework for treatment duration, ABO-CR scores, and ABO-DI. The GRADE certainty for reduced treatment duration and ABO-CR with customized PEA was rated low, likely due to study variation and biases as seen in Table 3. Certainty was downgraded based on GRADE domains: RoB (mixed study designs), inconsistency (heterogeneity in outcomes), and imprecision (wide confidence intervals). In contrast, the ABO-DI certainty was rated moderate, indicating higher confidence.

Table 3.

GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) Summary of Findings.

Customized PEA Compared to Conventional PEA for Treating Malocclusion
Patient or Population: Treating Malocclusion
Setting:
Intervention: Customized PEA
Comparison: Conventional PEA
Outcomes	Anticipated Absolute Effects* (95% CI)	No. of Participants (Studies)	Certainty of the Evidence	Comments
	Risk with Customized PEA
Treatment duration (months)	MD 4.37 lower (5.31 lower to 3.42 lower)	238 (4 non-randomized studies)	⨁⨁◯◯ Low	Downgraded for risk of bias (mixed designs) and inconsistency (I² = 88%)
ABO-CR Eval	MD 1.75 lower (5.4 lower to 1.91 higher)	192 (3 non-randomized studies)	⨁⨁◯◯ Low	Downgraded for RoB and inconsistency (moderate I²); wide CI crosses null
ABO-DI	MD 0.24 higher (1.81 lower to 2.3 higher)	192 (3 non-randomized studies)	⨁⨁⨁◯ Moderate	Downgraded for imprecision and indirectness

Notes: *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). ABO-CR, American Board of Orthodontics-cast-radiograph; ABO-DI, American Board of Orthodontics-Discrepancy Index; CI, confidence interval; MD, mean difference; PEA, pre-adjusted edgewise appliance; RoB, risk of bias.

GRADE Working Group grades of evidence:

High certainty: We are very confident that the true effect lies close to that of the estimate of the effect.

Moderate certainty: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.

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

Very low certainty: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimated effect.

Sensitivity and Subgroup Analysis

Sensitivity analyses were performed to assess the robustness of pooled estimates. For treatment duration, the random-effects model continued to show a statistically significant reduction in the customized group (MD = −3.91 months; 95% CI: −7.06, −0.76), despite high heterogeneity (I² = 88%). For ABO-DI and ABO-CR scores, results were consistent across fixed- and random-effects models, with no significant differences between customized and conventional systems. These analyses support the reliability of the observed treatment duration difference while highlighting the stability of ABO-DI and ABO-CR findings (Appendix C).

Subgroup analyses were conducted by appliance type (labial vs. lingual) and study design (RCTs vs. observational). The treatment duration benefit was more pronounced in studies using labially customized appliances. Lingual systems, though aesthetic, showed more patient-reported issues such as speech disturbances and discomfort. No consistent differences emerged in ABO-DI or ABO-CR outcomes across subgroups. These findings suggest that while customization may improve efficiency, appliance design and clinical context remain critical modifiers (Appendix D).

Discussion

Customized orthodontic appliances allow for precise and individualized treatment. The literature largely focuses on customized appliances like indirect bonding trays, aligners, and retainers.^{6, 7} To date, no comprehensive analysis has assessed the treatment efficacy of customized fixed orthodontic appliances. Thus, the aim of this systematic review was to compare treatment efficiency between customized- and conventional-fixed orthodontic appliances.

This review included nine studies, six observational^{7, 24–27, 29} and three RCTs,^{28, 30, 31} spanning diverse geographical regions. Participants were in their late teens to adulthood (mean age 20-30 years), with a slight skew toward females, with treatments involving lingual, labial, or self-ligating brackets.

This review provides strong evidence that customized systems like Incognito™ and Insignia™ offer several clinical advantages over conventional systems (e.g., Damon Q and Victory Series™), particularly in terms of shorter treatment durations. Patients treated with customized appliances completed treatment approximately 4 months earlier, a statistically significant and clinically relevant finding (P = .02), aligning with previous studies (Weber et al.⁷; Jackers et al.; Bardideh et al.) that also reported fewer unscheduled appointments and more efficient outcomes.⁹ A notable limitation of the meta-analysis is the substantial heterogeneity observed among the included studies (I² = 88%), indicating high variability in study designs, patient demographics, and types of customized systems used. Notwithstanding this variability, the overall effect remains robust, with the probability of a chance finding being minimal. Brown et al.²⁵ and Jackers et al.²⁹ found that the number of treatment appointments and overall duration were significantly lower for patients using customized systems compared to conventional systems.^{25, 29} Jackers et al. reported a difference of over 100 days in treatment duration between groups treated with customized systems and conventional Damon brackets.²⁹ Additionally, fewer unscheduled emergency appointments and bracket repositioning were required in customized systems. This could be ascribed to better precision in bracket placement and higher control over tooth movements, thereby contributing to fewer treatment delays and more predictable treatment outcomes. These findings are in contrast with Yassir et al.,¹³ who found no significant differences in treatment duration. This could be explained by their stricter inclusion criteria, which resulted in the inclusion of fewer, primarily prospective studies, limiting the evidence base.¹³

Clinical outcomes between customized and conventional orthodontic systems show varied results depending on the specific metric evaluated. For instance, studies indicate improvements in areas like treatment efficiency, but less so in others, such as the ABO-DI and ABO-CR scores. The meta-analysis revealed no statistically significant difference in ABO-DI scores between customized and conventional systems, exhibiting minimal heterogeneity (I² = 0%), indicating consistency across studies analyzed. This undermines the notion that customized systems produce more improvements in discrepancy indices vis-à-vis conventional PEA systems. Similarly, for ABO-CR scores, the analysis showed a slight, nonsignificant trend toward better scores with customized systems. However, there was moderate heterogeneity (I² = 60%), which may suggest some variability in the study’s results, but it was still insufficient to show a clear advantage of customized systems. Weber et al. highlighted that the total treatment time was shorter in the experimental group (using Insignia) than in the control group, with fewer unscheduled appointments and debonded brackets.²⁶ A more rapid realization of target outcomes, coupled with fewer in-treatment complications, contributes to better treatment efficiency. On a similar note, Penning et al.³¹ and Hegele et al.³⁰ reported greater precision in tooth movement with customized systems. These findings are pivotal for orthodontists seeking optimized treatment timelines and bolstering long-term stability.

Patient experience plays a vital role in the success of orthodontic treatment, especially for adult patients who place great emphasis on aesthetics and comfort. The studies in this review offer mixed results in terms of patient satisfaction with customized systems. Wu et al.²⁶ and Stamm et al.²⁷ found that patients treated with lingual systems like Incognito™ reported more oral discomfort, speech disturbances, and difficulties with mastication. These negative experiences seemed to subside over time, and patient satisfaction eventually became comparable to those treated with conventional systems.

Lingual systems are commonly associated with speech disturbances, particularly during the initial phase of treatment, as noted by studies such as Stamm et al.²⁷ Nonetheless, patients adjusted to the lingual system within a few months with minimal long-term effects on speech.²⁷ It may be surmised that the long-term benefits of customized lingual systems, especially in terms of aesthetics, may outweigh the initial short-term speech impediment.

A recent systematic review by Yassir et al. found no significant differences in treatment duration, treatment outcomes, number of appointments, analgesic consumption, or patient satisfaction between customized and non-customized orthodontic appliances.¹³ In contrast, the present meta-analysis reported a significant decrease in treatment duration with customized appliances. Yassir et al. followed a more exclusionary protocol, resulting in the inclusion of only four studies. A smaller pool of primary studies, along with variability in study design and quality, possibly impacted their findings. In contrast, this meta-analysis incorporated more studies, including rigorously designed RCTs, providing a more exhaustive dataset, allowing for stronger statistical power to detect differences.

Also, while Yassir et al.¹³ focused primarily on clinical parameters of treatment outcomes, this review incorporated a broader spectrum of treatment-related factors, such as treatment efficiency, patient compliance, orthodontic precision, unscheduled appointments, and emergency visits, providing a more nuanced comprehension of clinical efficiency.

In comparing our findings with other forms of customization in orthodontics, it is worth noting that the systematic review by Ke et al.,⁹ which evaluated the treatment effectiveness of clear aligners versus conventional fixed appliances. Their meta-analysis concluded that while clear aligners offered superior aesthetics, patient comfort, and a significantly shorter treatment duration by 6.31 months (95% CI [−8.37, −4.24]), they were less effective than conventional braces in achieving adequate occlusal contacts, torque control, and transverse expansion.

This aligns with our findings, where customized fixed appliances such as Insignia™ and Incognito™ also demonstrated shorter treatment durations. However, unlike clear aligners, they preserved the full biomechanical advantages of fixed appliances. While both systems aim for personalization, aligners rely on segmented tooth movements and exhibit torque and rotational control limitations. In contrast, customized fixed appliances offer a combination of digital precision and full-arch mechanics, potentially providing a more optimal balance between treatment efficiency and control.

These insights emphasize the need for future research directly comparing all three systems, namely, conventional, clear aligners, and fully customized fixed appliances, to determine context-specific advantages and limitations.

Limitations and Future Research

Although they have a number of drawbacks, customized orthodontic systems show promise. The absence of subgroup-stratified outcome data from studies, which precluded quantitative subgroup analyses, was a limitation of the meta-analysis. This made it more difficult to investigate effect-modifiers such as patient age or appliance type. The heterogeneity of the study draws attention to differences in populations, interventions, and study designs. Subgroup-specific results or patient data should be reported in future research. The cost, which is frequently overlooked in research, is much greater than that of traditional systems, which restricts accessibility in areas with limited resources. Additionally, treatment may be delayed due to the longer planning time, particularly with CAD/CAM-based approaches. Twenty-seven studies’ sample sizes and follow-up times varied, and bias was introduced by smaller cohorts and retrospective designs. For results to be generalizable, larger, carefully planned trials are required.

Clinical Recommendations

Given their potential to reduce treatment duration and offer digitally guided precision, customized PEAs may be particularly suited for adult patients prioritizing aesthetics and efficiency. Although no significant differences were observed in ABO-DI and ABO-CR scores, customized systems can be advantageous in managing complex malocclusions requiring individualized mechanics. Long-term treatment success, however, depends on robust retention protocols and ongoing relapse surveillance. Strategic integration into clinical practice should be guided by case selection and tailored treatment planning.

Conclusions

Customized fixed orthodontic appliances may offer improved treatment efficiency, particularly in reducing overall treatment duration. However, these potential benefits were not consistently accompanied by improvements in treatment quality as measured by ABO indices. Significant heterogeneity across studies limits the strength of pooled conclusions, and the certainty of evidence remains low to moderate. Customization should therefore be considered a potentially valuable adjunct in appropriate cases, but not yet a replacement for sound biomechanical planning and clinical execution. Further well-designed, adequately powered randomized trials are needed to confirm these findings and guide routine clinical use.

Footnotes

Availability of Supporting Data

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Ethical Approval and Informed Consent

Not applicable.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Shubhnita Verma

Prasad Chitra

Appendix A: PICOS (Participants,Intervention,Comparison,Outcomes,Study Design) Framework for Eligibility Criteria

Appendix B: Search Strategy for Electronic Databases

Appendix C: Sensitivity Analysis

Appendix D: Subgroup Analysis

Qualitative Subgroup Analysis 1.

By appliance type (lingual vs. labial; customized vs. conventional)

Treatment duration:

Lingual customized (e.g., Ata-Ali 2020 Incognito™) showed longer mean treatment duration (~2.78 years) than labial conventional (Ata-Ali Labial group) (~2.43 years). This aligns with Figure 4a showing Ata-Ali 2020 with a positive mean difference favoring conventional PEA in treatment duration.

ii.

Other studies using labial customized appliances (Penning et al.; Brown et al.; Jackers et al.; Weber et al.; Hegele et al.) mostly show shorter treatment durations compared to their conventional counterparts.

iii.

For example, from Penning et al.,³¹ there is a modest difference where treatment durations are similar but slightly longer in the customized group (1.29 vs. 1.24 years, respectively).

iv.

Weber et al.⁷ and Jackers et al.²⁹ report significantly shorter treatment durations with customized labial appliances (14.23 vs. 22.91 months, 393 vs. 497 days).

Summary: Labial customized appliances tend to reduce treatment time relative to conventional labial appliances, while lingual systems tend to have longer or similar durations.

ABO-DI and ABO-CRE scores:

Ata-Ali’s data show slightly lower ABO-CRE and ABO-DI scores with lingual customized appliances (Incognito) relative to labial conventional (Victory), but differences are small and statistically uncertain.

ii.

Penning et al. showed comparable orthodontic outcome quality (PAR reduction) between customized and conventional groups.

iii.

Hegele et al. report median ABO score reductions of 32 points in both customized and conventional groups, indicating similar finishing quality.

iv.

Jackers et al. also show similar ABO-CRE scores between CAD/CAM customized and conventional brackets.

Summary: The finishing quality, as measured by ABO-DI and ABO-CRE, does not display consistent or significant differences between customized and conventional brackets, regardless of appliance type.

Subgroup impact on other outcomes:

Higher bracket failure rates in customized groups are noted in Penning et al. and Hegele et al.

ii.

Patient complaints are consistently higher with customized appliances (Penning et al.).

iii.

Oral comfort and speech disturbance were worse with customized lingual appliances (Wu et al.).

iv.

Treatment planning time is longer with customized systems (Penning et al.; Yassir et al. review).

Subgroup analysis conclusion:

Customized appliance effects differ by appliance type and outcome. Labial customized appliances tend to shorten treatment duration, but lingual customized appliances do not consistently show this benefit. Clinical finishing outcomes are comparable across groups. Side effects like bracket failures, treatment planning time, and patient complaints tend to be greater with customized systems, especially lingual. These subgroup patterns should be interpreted cautiously, pending formal meta-analysis and individual patient data.

References

Wahl

Orthodontics in 3 millennia. Chapter 16: late 20th-century fixed appliances. Am J Orthod Dentofacial Orthop . 2008;134(6):827–830. doi:10.1016/j.ajodo.2008.04.016

Mundhada

, Jadhav

, Reche

A review on orthodontic brackets and their application in clinical orthodontics. Cureus . 2023;15(10):e46615. doi:10.7759/cureus.46615

Silverman

, Cohen

, Gianelly

, Dietz

VS.

A universal direct bonding system for both metal and plastic brackets. Am J Orthod . 1972;62(3):236–244. doi:10.1016/s0002-9416(72)90264-3

Patano

, Inchingolo

, Malcangi

, . Direct and indirect bonding techniques in orthodontics: a systematic review. Eur Rev Med Pharmacol Sci . 2023;27(17):8039–8054. doi:10.26355/eurrev_202309_33565

Panayi

NC.

In-office customized brackets: aligning with the future. Turk J Orthod . 2023;36(2):143–148. doi:10.4274/TurkJOrthod.2023.2023.21

Grauer

Quality in orthodontics: the role of customized appliances. J Esthet Restor Dent . 2021;33(1):253–258. doi:10.1111/jerd.12702. PMID: 33410248.

Weber

2nd , Koroluk

, Phillips

, Nguyen

, Proffit

WR.

Clinical effectiveness and efficiency of customized vs. conventional preadjusted bracket systems. J Clin Orthod . 2013;47(4):261–268.

, Zhu

A comparison of treatment effectiveness between clear aligner and fixed appliance therapies. BMC Oral Health . 2019;19(1):24. Published 2019 Jan 23. doi:10.1186/s12903-018-0695-z

Bardideh

, Ghorbani

, Shafaee

, Saeedi

, Younessian

A comparison of CAD/CAM-based fixed retainers versus conventional fixed retainers in orthodontic patients: a systematic review and network meta-analysis. Eur J Orthod . 2023;45(5):545–557. doi:10.1093/ejo/cjad033

10.

Cunha

TMAD

, Barbosa

IDS

, Palma

KK.

Orthodontic digital workflow: devices and clinical applications. Dental Press J Orthod . 2021;26(6):e21spe6. doi:10.1590/2177-6709.26.6.e21spe6. PMID: 34932716; PMCID: PMC8690351.

11.

Ormco-Corporation. Increasing Clinical Performance with 3D Interactive Treatment Planning and Patient-specific Appliances . Orange, CA: Ormco-Corporation; 2006.

12.

Wiechmann

, Rummel

, Thalheim

, Simon

, Wiechmann

Customized brackets and archwires for lingual orthodontic treatment. Am J Orthod Dentofacial Orthop . 2003;124(5):593–599. doi:10.1016/j.ajodo.2003.08.008

13.

Yassir

, Sofar

, McIntyre

, Bearn

DR.

Clinical effectiveness of customized versus noncustomized orthodontic appliances: a systematic review. J Orthod Sci . 2024;13(1):26. doi:10.4103/jos.jos_46_24

14.

Liberati

, Altman

, Tetzlaff

, . The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. J Clin Epidemiol . 2009;62:e1–34.

15.

Ouzzani

, Hammady

, Fedorowicz

, Elmagarmid

Rayyan-a web and mobile app for systematic reviews. Syst Rev . 2016;5:210.

16.

Higgins

JPT

, Thomas

, Chandler

, . Cochrane Handbook for Systematic Reviews of Interventions Version 6.5. Cochrane; 2024 . https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current

17.

Sterne

, Hernán

, Reeves

, . ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. BMJ . 2016;355:i4919.

18.

Sterne

JAC

, Savović

, Page

, . RoB 2: a revised tool for assessing risk of bias in randomised trials. BMJ . 2019;366:l4898.

19.

Spineli

, Pandis

The importance of careful selection between fixed-effect and random-effects models. Am J Orthod Dentofacial Orthop . 2020;157:432–433.

20.

Higgins

, Thompson

, Deeks

, Altman

DG.

Measuring inconsistency in meta-analyses. BMJ . 2003;327:557–560.

21.

Ioannidis

JP.

Interpretation of tests of heterogeneity and bias in meta-analysis. J Eval Clin Pract . 2008;14:951–957.

22.

Egger

, Davey Smith

, Schneider

, Minder

Bias in meta-analysis detected by a simple, graphical test. BMJ . 1997;315:629–634.

23.

Guyatt

, Oxman

, Akl

, . GRADE guidelines: 1. Introduction-GRADE evidence profiles and summary of findings tables. J Clin Epidemiol . 2011;64:383–394.

24.

Ata-Ali

, Ata-Ali

, Lanuza-Garcia

, . Clinical outcomes of lingual fully customized vs. labial straight wire systems. J Orofac Orthop . 2021;82:13–22. doi:10.1007/s00056-020-00248-0

25.

Brown

, Koroluk

, Ko

, Zhang

, Chen

, Nguyen

Effectiveness and efficiency of a CAD/CAM orthodontic bracket system. Am J Orthod Dentofacial Orthop . 2015;148(6):1067–1074. doi:10.1016/j.ajodo.2015.07.029

26.

, McGrath

, Wong

, Wiechmann

, Rabie

AB.

Comparison of oral impacts experienced by patients treated with labial or customized lingual fixed orthodontic appliances. Am J Orthod Dentofacial Orthop . 2011;139(6):784–790. doi:10.1016/j.ajodo.2009.07.027

27.

Stamm

, Hohoff

, Ehmer

A subjective comparison of two lingual bracket systems. Eur J Orthod . 2005;27(4):420–426. doi:10.1093/ejo/cji034

28.

Kaptaç

, Ay Ünüvar

Customized lingual brackets vs. conventional labial brackets for initial alignment. J Orofac Orthop . 2022;83:307–317. doi:10.1007/s00056-021-00295-1

29.

Jackers

, Maes

, Lambert

, Albert

, Charavet

Standard vs. computer-aided design/computer-aided manufacturing customized self-ligating systems using indirect bonding with both. Angle Orthod . 2021;91(1):74–80. doi:10.2319/012920-59.1

30.

Hegele

, Seitz

, Claussen

, Baumert

, Sabbagh

, Wichelhaus

Clinical effects with customized brackets and CAD/CAM technology: a prospective controlled study. Prog Orthod . 2021;22(1):40. doi:10.1186/s40510-021-00386-0

31.

Penning

, Peerlings

RHJ

, Govers

JDM

, . Orthodontics with customized versus noncustomized appliances: a randomized controlled clinical trial. J Dent Res . 2017;96(13):1498–1504. doi:10.1177/0022034517720913

Comparison of Treatment Efficiency Between Customized Fixed and Conventional Fixed Orthodontic Appliances: A Systematic Review and Meta-analysis

Abstract

Objective

Materials and Methods

Results

Conclusion

Keywords

Introduction

Materials and Methods

Eligibility Criteria

Search Strategy

Screening and Selection of Papers

Data Collection, Items, and Processing

Assessment of Quality and Risk of Bias (RoB) of Included Studies

Summary Measures and Data Synthesis

Certainty Assessment

Results

Study Selection (Figure 1)

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 Flow Diagram.

Study Characteristics

Characteristics of the Studies Included in the Systematic Review.

Narrative Synthesis Table for Non-pooled Secondary Outcomes.

RoB in Studies (Figures 2 and 3)

ROBINS-I (Risk of Bias in Non-randomized Studies—of Interventions) of Included Studies.

RoB 2 (Risk of Bias 2) of Included Studies.

Results of Meta Analysis (Figure 4)

Treatment Duration (Figure 4a)

Results of Meta-analysis. (a) Treatment Duration. (b) American Board of Orthodontics-Discrepancy Index (ABO-DI) and (c) American Board of Orthodontics-cast-radiograph (ABO-CR).

ABO-DI (Figure 4b)

ABO-CR (Figure 4c)

Analysis of the Certainty of the Evidence

GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) Summary of Findings.

Sensitivity and Subgroup Analysis

Discussion

Limitations and Future Research

Clinical Recommendations

Conclusions

Footnotes

Availability of Supporting Data

Declaration of Conflicting Interests

Ethical Approval and Informed Consent

Funding

ORCID iDs

Appendix A: PICOS (Participants,Intervention,Comparison,Outcomes,Study Design) Framework for Eligibility Criteria

Appendix B: Search Strategy for Electronic Databases

Appendix C: Sensitivity Analysis

Appendix D: Subgroup Analysis

References