Evaluation of different methods of correcting deep bite in adult and adolescent patients: a systematic review and meta-analysis

Abstract

Background

A deep bite is a prevalent malocclusion, and its treatment remains one of the most debated topics in orthodontics due to the variety of underlying causes and the diverse orthodontic approaches employed to address it.

Objective

This systematic review aimed to assess the evidence on the most effective approach for treating deep bites in adult and adolescent patients.

Search methods

A thorough search was performed up to January 2025 among these databases: PubMed^®, the Cochrane Library, Scopus^®, Web of Science™, Embase^®, and Google™ Scholar.

Selection criteria

Only randomized controlled trials (RCTs) were included in this review on adult and adolescent patients with deep bite malocclusion who underwent any orthodontic treatment to correct this malocclusion.

Data collection and analysis

The Cochrane tool (ROB2) was employed to assess the risk of bias, while the GRADE approach was used to evaluate the quality of evidence.

Results

Eight RCTs were included in this review. Five of the eight studies were suitable for qualitatively synthesizing the data. The meta-analysis showed that the miniscrew-supported intrusion (MSI) caused a statistically significant amount of overbite reduction (mean difference (MD) = - 0.36 mm), upper incisor intrusion (MD = - 0.77 mm), and upper incisor proclination (MD = 0.63^o) compared to the Connecticut intrusion arch (CIA), and the quality of evidence was low to moderate. Moderate-quality evidence indicated that there was no statistically significant difference between the anterior bite turbos (ABT) and the lower reversed curve of Spee (RCS) regarding overbite reduction (MD= - 4.07 mm, MD = - 3.27 mm, respectively). A low-quality evidence indicated that the MSI and the utility arch (UA) caused more overbite reduction than the J-Hook headgear (J-Hg) (MD = -2.33 mm, MD = - 2 mm, MD = - 0.8 mm, respectively). However, the MSI was superior regarding upper incisor intrusion than the UA and the J-Hg (MD = - 2.08 mm, MD = - 1.33 mm, MD= - 0.1 mm, respectively).

Conclusion

Low-quality evidence suggests that MSI is superior to CIA for reducing overbite, and causing more upper incisor proclination. Moderate -quality evidence indicates that MSI is superior to CIA for intruding the upper incisors. Moderate-quality evidence indicates that the ABT and the RCS effectively reduce overbite. Low-quality evidence suggests that the MSI and the UA cause more overbite reduction and upper incisor intrusion than the J-Hook headgear, and the MSI causes more upper incisor intrusion than the UA.

Registration

The protocol was registered in the PROSPERO database (CRD42025633739) during the first stages of the review.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40510-025-00586-y.

Introduction

A deep bite is defined as an overbite in which the upper incisor crowns overlap more than one-third of the lower crowns in centric or habitual occlusion [1]. A severe deep bite in which the overbite is more than 5 mm was found in 20% of children and 13% of adults in the U.S. population; thus, it is among the most prevalent vertical abnormalities that coexist with different malocclusions [2]. The management of deep bite and its maintenance is always a challenge [3]. In order to treat deep bites properly, it is important to understand their etiology. A deep bite can be caused by a variety of skeletal or dental factors; therefore, it should not be treated as a distinct malocclusion but rather as a clinical presentation of skeletal or dental problems [4].

Nevertheless, since deep bite results in harm to palatal mucosa, gingival recession, and tooth wear, and it has also been suggested as a potential factor in temporomandibular joint disorders, managing it is one of the objectives of orthodontic therapy [3, 5, 6]. Basically, deep bites can be treated in three ways: incisor intrusion, posterior teeth extrusion, and incisor protrusion [4]. Extrusion of the posterior teeth is the preferred treatment for individuals with short lower facial height, excessive curve of Spee, and moderate to minimum incisor display [10]. This movement is very favorable and has proven to be fairly stable in growing patients with skeletal deep bite as long as the free-way space is not violated. However, in adults, the stability of such movement is questionable due to muscle forces and occlusal stresses [4]. This might explain the shortage of studies that discuss the management of skeletal deep bites in adults and adolescents. Several methods, such as anterior bite planes and reverse curve of Spee, can be used to achieve that [10]. Anterior bite planes come in several forms, including removable bite planes, custom-made composite or glass ionomer bite planes, fixed anterior acrylic bite planes, bite turbos, bite ramps, and bite bumpers. They produce a posterior occlusal gap that permits the erupting of the posterior teeth while maintaining the occlusal stresses on the incisors [4]. Engaging the mandible with a reverse curve of Spee archwire leads to similar effects. It opens the bite primarily by extrusion of the molars and by flaring the incisors [10]. Incisor intrusion is indicated in patients with long lower facial height, excessive gingival display, and overeruption of the incisors [10]. Given that it is a useful and generally stable method for treating deep bites in adult patients [10, 11], the majority of studies relied on upper incisor intrusion and employed various techniques to achieve it. It has been demonstrated that miniscrews, headgear, utility arches, and conventional intrusion arches are effective ways of incisor intrusion [12–17].

The most used appliance for treating deep bites in growing patients is the anterior acrylic bite plane, according to the most recent systematic review of the therapy of deep bites in growing patients [18]. Due to the paucity of research in this field, the evidence is currently insufficient. On the other hand, the optimal modality for treating deep bites in adults and adolescents remains unclear in the current literature.

Systematic reviews on the topic of correcting deep bites in adults and adolescents were few in the available literature. Several systematic reviews have examined the impact of different intrusion approaches and concentrated on the effects of miniscrew-supported intrusion while contrasting it with other techniques [19–21]. A systematic review of Gupta et al. compared the effects of miniscrew-supported intrusion and the conventional maxillary incisor intrusion. However, the primary outcomes were the maxillary incisors and molar inclination, while the overbite changes and the upper incisor intrusion were secondary outcomes. Also, the authors included studies without age limitations; i.e., adults and growing patients were included [20]. Another systematic review has been conducted by Shakti et al., who discussed the effects of miniscrew-supported intrusion compared only to the conventional intrusion arch (CIA), and they included both randomized clinical trials (RCTs) and controlled clinical trials (CCTs) in their synthesis of the results [21]. The most recent systematic review in this regard evaluated the effect of miniscrew-supported intrusion compared to any other method of intrusion. The sources of information for this SR comprised prospective cohort studies, retrospective cohort studies, controlled clinical trials, and randomized clinical trials [19]. Till now, no systematic review has evaluated the evidence concerning all possible orthodontic techniques of incisor intrusion and posterior extrusion during deep bite correction in adult and adolescent patients. Furthermore, the evidence regarding this issue has not been solely based on randomized controlled trials (RCTs), which in turn would strengthen the quality of the evidence. Thus, the aim of this systematic review is to respond to the following specific review question: What is the best orthodontic treatment modality for correcting deep bites in adult and adolescent patients?

Materials and methods

Preliminary search and protocol registration

Before creating the final protocol of this systematic review, a PubMed pilot search was first conducted to ensure there were no comparable ones and to find any relevant studies. The protocol was documented in PROSPERO during the first stages of this study (CRD42025633739). This systematic review was conducted using the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [22, 23], along with the checklist and the methodologies detailed in the Cochrane Handbook for Systematic Reviews of Interventions [24].

Eligibility criteria

The inclusion and exclusion criteria were well-defined in this systematic review. To identify individuals, interventions, comparisons, outcomes, and research design, the PICOS (Population, Intervention, Comparison, Outcomes, and Research) framework was employed. The target population was patients aged between 14 and 25 years, with an overbite ≥ 4 mm, regardless of the origin of the deep bite and the class of malocclusion. The intervention was any orthodontic treatment that opens the bite. The comparison was any other kind of treatment that opens the bite that is different from the intervention group, or no intervention at all. The primary outcome of these criteria was the amount of overbite correction. The secondary outcomes were the amount of upper incisor intrusion, upper incisor inclination, upper first molar vertical change, lower first molar vertical change, lower incisor linear and angular changes, and lower facial height changes. Only randomized controlled trials (RCTs) were considered in this systematic review.

The excluded studies were the following: studies that did not identify adults and adolescents with deep bite as research participants and included patients without age limitation; studies that did not report a sample; studies with fewer than ten patients in the experimental group; controlled clinical trials; cohort studies; case reports; case series reports; retrospective studies, personal opinions; reviews; and technique description articles.

Information sources

Table 1 contains the list of keywords utilized in the electronic search, whereas supplementary Table 1 presents the details of the search strategy. Two reviewers (OAR and MYH) did the primary search in January 2025 without setting a time restriction using PubMed^®, Web of Science™, Scopus^®, Google™ Scholar, and Cochrane Library. A manual search of the bibliographies from all the included articles was carried out to identify additional relevant papers.

Table 1.

Keywords used in the electronic search

Type of malocclusion	Permanent dentition, permanent occlusion, deep bite, deep overbite, increased overbite, excessive overbite
Treatment planning	Incisor intrusion, anterior teeth intrusion, molar extrusion, posterior teeth extrusion, Relative intrusion, Absolute intrusion
Outcomes	The amount of overbite correction, the duration of deep bite correction, upper incisor intrusion, upper incisor proclination, lower incisor intrusion, lower incisor proclination, upper molar extrusion, lower molar extrusion, the lower facial height changes
Intervention	Miniscrew, mini implant, temporary anchorage device, intrusion arch, Burstone’s intrusion arch, conventional intrusion arch, Connecticut intrusion arch, utility arch, bite plane, anterior bite plane, bite turbos, bite ramps, bite bumper, reverse curve of Spee

Search strategy and study selection

The procedure of selecting the articles was divided into two phases. The two reviewers (OAR and MYH) independently went over the titles and abstracts of the articles that were located using the electronic search engines in the first stage, then evaluated the full texts of the possible articles in the second stage. After that, the two reviewers excluded the articles that did not meet the inclusion criteria. In case of disagreement, the two reviewers worked through it with the third author (MKA) until a solution was found.

Data collection process

Data were retrieved from the included studies and organized into tables by two reviewers (OAR and MYH). The collected data included: general information (such as author name and publication year), study design, mean age, number of patients, types of malocclusion, types of interventions, follow-up duration, treatment duration, and outcomes. The two reviewers settled their disagreements through conversation and, if necessary, reached out to the third author (MKA).

Risk of bias assessment in individual studies

The two reviewers separately evaluated the risk of bias of the included studies using the RoB-2 tool [25]. After that, the evaluations from the two reviewers were compared; if there were any discrepancies, the reviewers collaborated with the third review author (MA) to address them until they could reach a consensus. The following domains were categorized as “low,” “high,” or “some concerns”: bias stemming from the randomization process, bias due to deviations from the intended interventions, bias resulting from missing outcome data, bias in the outcome measurement, and bias related to the selection of the reported result. The overall risk of bias in the selected studies was determined based on the following criteria: a “low risk of bias” was assigned when all domains were rated as “low risk of bias”; “some concerns” were noted if at least one domain was rated as “some concern” but none were classified as “high risk of bias”; and “high risk of bias” was assigned if one or more domains were rated as “high risk of bias” or if multiple domains raised concerns that notably diminished confidence in the results. The evidence quality was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) method [26].

Data synthesis

The meta-analysis was conducted using the Review Manager software (RevMan), Version 5.4. (Copenhagen: The Nordic Cochrane Center, the Cochrane Collaboration). The random-effects model with the inverse variance method and the mean difference with the associated 95% confidence intervals (CIs) were the analysis methods for continuous outcomes. A P-value of less than 0.05 was used to detect significant heterogeneity, while the I² index measured the percentage of heterogeneity across studies. The results of the forest plots are displayed through graphical analysis. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guidelines were applied to evaluate the quality of the evidence comprehensively.

Results

Study selection

1252 articles were identified after the electronic and manual search; the number dropped to 578 when duplicates were eliminated. After reading the titles and abstracts of these publications, ten potential articles remained eligible, and those that did not fit the inclusion criteria were eliminated. Upon reviewing the full text of all ten studies, two were found not to fit the inclusion criteria. The reasons behind the exclusion of each study are explained in Table 2. Eight papers were included in the qualitative synthesis of the data. Figure 1 shows the PRISMA flow diagram of the reviewing process.

Table 2.

Excluded articles and the reasons beyond exclusion

Authors	Title	Reasons beyond exclusion
Schwertner et al., 2020 [17]	A prospective clinical trial of the effects produced by the Connecticut intrusion arch on the maxillary dental arch	They included patients with mixed dentition.
Nasser et al., 2023 [16]	Investigating the Effectiveness of Low-Level Laser in Reducing Root Resorption of the Upper Incisors During Intrusion Movement Using MiniImplants in Adult Patients With Deep Overbite: A Randomized Controlled Clinical Trial	The study concentrated on the root resorption and did not discuss the amount of deep bite correction which is the primary outcome in this systematic review.

Fig. 1.

PRISMA flow diagram of the included studies

Study characteristics

Table 3 summarizes the characteristics of the included studies. Eight randomized controlled trials were included in this systematic review. The overall number of patients was 296. Two studies failed to provide the gender distribution [13, 27], so out of 242 patients, 81 were males and 134 were females. The age range of the included patients was between 14 and 22.6 years.

Table 3.

Characteristics of included trials

Authors	Number of patients/mean age	Malocclusion type/inclusion criteria	Intervention	Outcome measures	Outcomes	Follow up period
Senışık and Türkkahraman, 2012 [29]	45 patients Control: 15 (7 m, 8 f) 20.49 ± 2.80 years MSI: 15 (6 m 9 f) 20.13 ± 2.48 years CIA: 15(6 m, 9 f) 20.32 ± 3.22 years	Patients with permanent dentition, class 2 div II with an overbite > 4 mm, and more than 4 mm coverage of the upper incisors by the lower lip.	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: Connecticut intrusion arch to intrude the upper incisors Group 3: untreated	Lateral cephalograms, orthopantomographs, intraoral and extraoral photographs, and study casts	The amount of overbite correction, the amount of upper incisor intrusion, upper incisor inclination, the vertical position of the lower incisor, lower incisor inclination, the amount of upper first molar extrusion, the amount of lower first molar extrusion, and the facial height changes	Treatment time was limited to 7 months, if required, maxillary incisor intrusion was continued after the study period.
Jain et al., 2014 [14]	30 patients (11 m, 19 f) 16–22 years MSI: 10 J-Hg: 10 UA: 10	Patients with deep overbite > 4 mm, excessive incisal display, and average to vertical growth pattern.	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: J-Hook headgear Group 3: Utility arch	Maxillary anterior occlusal radiographs, intraoral and extraoral photographs, and intra-oral periapical radiographs	The amount of overbite correction,, the amount of upper incisor intrusion, the amount of upper first molar extrusion, the distance from the upper incisor’s incisal edge to the upper lip	4 months
Gürlen and Aras, 2016 [28]	32 patients MSI: 16 (8 m, 8 f) 14 ± 0.5 years CIA: 16 (8 m, 8 f) 14 ± 0.83 years	Patients with normal or increased vertical dimension, overbite > 5 mm, and increased display of the upper incisors without flaring.	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: CIA for the upper incisors	Lateral cephalograms and periapical radiographs	The amount of overbite correction, the amount of upper incisor intrusion, upper incisor inclination, lower anterior facial height	4 months after the initiation of the intrusion.
Gupta et al., 2017 [13]	24 patients MSI: 12 patients 17.75 ± 3.49 years CIA: 12 patients 18.75 ± 3.47 years	Overbite ≥ 4 mm, average growth pattern, and maxillary incisor display of more than 3 mm.	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: CIA for the upper incisors	Lateral cephalograms	The amount of overbite correction, the amount of upper incisor intrusion, the amount of upper first molar extrusion, the distance from the upper incisor’s incisal edge to the upper lip, lower anterior facial height	Until the desired amount of intrusion was achieved.
Kahraman et al., 2017 [15]	36 patients MSI: 18 (5 m, 13 f) 16.6 ± 0.92 years CIA: 18 (4 m, 14 f) 15.99 ± 0.96 years	Supra-positioning of upper incisor teeth according to the occlusal plane, increased overbite (> 4 mm), increased gingival display on posed smile (≥ 2 mm), increased incisor display at rest (≥ 3 mm), post-pubertal period.	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: CIA for the upper incisors	CBCT	The amount of upper incisor intrusion, the amount of upper first molar extrusion,	Until the intrusion was done.
Kumar et al., 2017 [27]	30 patients Aged between 15–20 years MSI: 15 CIA: 15	Patients aged between 15 and 20 years, class 2 div I malocclusion, and overbite > 6 mm.	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: CIA for the upper incisors	Study casts, lateral cephalograms, and orthopantomograph	Upper incisor intrusion, upper incisor inclination, upper molar extrusion	6 months after the start of the intrusion.
El Namrawy et al., 2019 [12]	30 patients (9 m, 21 f) MSI: 15 (3 m, 12 f) 19.5 ± 2.5 years CIA: 15 (6 m, 9 f) 22.6 ± 5.3 years	Post-pubertal patients, class I or class II malocclusion, excessive gingival display on smiling, overbite ≥ 4 mm	Group 1: Miniscrew-supported intrusion of the upper incisors Group 2: CIA for the upper incisors	Study casts and lateral cephalograms	The amount of overbite correction, the amount of upper incisor intrusion, upper incisor inclination, the amount of upper first molar extrusion, upper first molar inclination, lower anterior facial height	After 6 months of the initiation or if one of the following was noticed: (1) reaching adequate overbite, (2) severe inflammation or miniscrew failure.
Al-Zoubi and Al-Nimri, 2022 [30]	42 patients RCS: 21 (9 m, 12 f) 18.4 ± 2.8 years ABT: 21 (8 m, 13 f) 18.2 ± 3.1 years	Overbite ≥ 50%, patients whose treatment plan did not include extraction of lower teeth and any extrusive mechanics	Group 1: RCA Group 2: ABT	Lateral cephalograms	The amount of overbite correction, upper incisor intrusion, upper incisor inclination, upper first molar vertical change, lower first molar vertical change, lower facial height.	Until an average overbite was achieved.

MSI: miniscrew-supported intrusion anchorage device, CIA: Connecticut intrusion arch, m: male, f: female, J-Hg: J-Hook headgear, UA: utility arch, RCS: reversed curve of spee, ABT: anterior bite turbos

Six studies compared the effectiveness of the Connecticut intrusion arch (CIA) with the miniscrew-supported intrusion (MSI) of the maxillary incisors; five of these studies included two groups [12, 13, 15, 27, 28], while one included three groups with a third control group of untreated patients [29]. On the other hand, Jain et al. compared the MSI of upper anterior teeth, the utility arch, and the J-hook Headgear (J-Hg) in the intrusion of upper incisors [14]. However, the anterior bite turbos (ABT) and the lower reversed curve of Spee (RCS) were evaluated by Al-Zoubi and Al-Nimiry. Both interventions were considered to have different mechanisms for managing deep bites compared to the previously mentioned seven papers, since the latter techniques primarily induce more posteriorly extrusive movement [30].

The dentoalveolar and skeletal changes were measured using a variety of evaluation tools. Radiographs were utilized in all eight studies [12–15, 27–30]. Among these, seven studies used lateral cephalograms [12–14, 27–30], and one employed CBCT [15]. Additionally, one of the seven studies incorporated periapical radiographs with lateral cephalograms [28], while two studies combined study casts with lateral cephalograms [12, 29].

The variables also differed among the studies. Six studies evaluated the amount of overbite correction [12–14, 28–30], whereas the amount of incisor intrusion was assessed in the eight studies [12–15, 27–30]. The vertical change of the upper first molar was measured in seven studies [12–15, 27, 29, 30], while the incisor inclination was measured in five studies [12, 27–30]. Five studies evaluated the anterior facial height changes [12, 13, 28–30]. However, the vertical changes of the lower first molar, the lower incisor intrusion, and inclination were only measured in two studies [29, 30].

The duration of effective treatment varied among the eight studies, as it lasted four months in two studies [14, 28], six months in two other studies [12, 27], and seven months in another study [29]. However, in three studies, the active treatment lasted until reaching a normal overbite [13, 15, 30]. The eight studies did not report on patient follow-up following the effective treatment [12–15, 27–30].

Risk of bias within studies

Eight randomized controlled trials were included in this systematic review [12–15, 27–30]. Two of the eight studies were classified as “low risk of bias” [28, 30], five were classified as “some concerns” [12–14, 27, 29], and one was classified as “high risk of bias” [15]. Figure 2 demonstrates the total risk of bias, while the argument behind the decision is explained in Supplementary Table 2.

Fig. 2.

Risk of bias summary: The review authors’ assessments of each risk of bias item for the included studies

Effects of interventions

A summary of the main findings of the included studies is given in Table 4. Results were organized across outcome categories, including overbite reduction, upper incisor intrusion, upper incisor inclination, upper and lower molar vertical changes, lower anterior facial height, and lower incisor linear/angular changes.

Table 4.

Outcomes of included trials

Authors		O.B Ch	U1/L1 intrusion		U1/L1 inclination			U6/L6 vertical changes			LAFH changes
Senışık and Türkkahraman, 2012 [29]	MSI	−2.27 ± 0.59 −2.10 ± 1.20 0.00 ± 0.00 S	U1 −2.47 ± 0.81 −2.20 ± 0.90 0.00 ± 0.00 S	L1: 0.43 ± 0.42 0.23 ± 0.32 0.00 ± 0.00 S	U1: 8.10 ± 5.17 4.87 ± 5.64 0.00 ± 0.00 S	L1 2.20 ± 2.07 1.20 ± 3 −0.10 ± 0.85 S		U6 0.00 ± 0.00 0.80 ± 0.65 0.03 ± 0.13 S	L6: 0.13 ± 0.30 −0.10 ± 0.21 0.03 ± 0.13 S		−0.07 ± 0.32 0.20 ± 0.44 0.33 ± 0.59 NS
	CIA
	C
Jain et al., 2014 [14]	MSI	−2.33 ± 0.16 −0.8 ± 0.29 −2 ± 0.05	U1 −2.08 ± 0.04 −0.1 ± 0.14 −1.33 ± 0.33					U6 −0.17 ± 0.22 0.20 ± 0.04 0.75 ± 0.1
	J-Hg
	UA
Gürlen and Aras, 2016 [28]	MSI	−3.27 ± 0.86 −2.05 ± 1.09 S	U1 −2.45 ± 0.59 −1.49 ± 0.98 S		U1: 9.38 ± 3.51 6.62 ± 3.36 S						0.26 ± 0.94 0.82 ± 1.15 NS
	CIA
Gupta et al., 2017 [13]	MSI	−2.46 ± 1.21 −2.04 ± 1.37 NS	U1 −2.46 ± 1.21 −1.75 ± 0.72 NS		U1: 3.75 ± 3.86 1.92 ± 5.2 NS			U6 0.17 ± 0.75 0.33 ± 0.49 NS			−0.67 ± 1.30 −0.21 ± 0.94 NS
	CIA
Kahraman et al., 2017 [15]	MSI		U1 −1.46 −1.78					U6 −0.06 ± 0.41 0.18 ± 0.6 NS
	CIA
Kumar et al., 2017 [27]	MSI		U1 −3.10 ± 0.67 −2.07 ± 0.53 S		U1: −0.93 ± 1.27 +3.73 ± 1.28 S			U6 0.97 ± 0.4 1.20 ± 0.32 NS
	CIA
El Namrawy et al., 2019 [12]	MSI	−2.6 ± 0.8 −2.9 ± 0.8 NS	U1 −2.6 ± 1.9 −2.3 ± 1.8 NS		U1: 2.3 ± 5.7 7.9 ± 4.7 S			U6 0.00 ± 0.00 −0.1 ± 0.3 NS			0.1 ± 0.3 0.3 ± 0.6 NS
	CIA
Al-Zoubi and Al-Nimri, 2022 [30]	RCS	−4.07 ± 0.69 −3.87 ± 0.72 NS	U1 + 0.02 ± 0.07 −0.43 ± 0.63 S	L1 −1.01 ± 0.80 −0.28 ± 0.50 S	U1 : 0.37 ± 0.58 1.47 ± 1.22 S		L1: 5.47 ± 2.56 2.28 ± 1.80 S	U6: 0.05 ± 0.05 0.08 ± 0.07 NS		L6:0.90 ± 0.46 1.29 ± 0.46 S	−0.09 ± 0.54 0.41 ± 0.42 S
	ABT

MSI: miniscrew-supported intrusion, CIA: Connecticut intrusion arch, C: control, J-Hg: J-Hook headgear, UA: utility arch, RCS: reversed curve of spee, ABT: anterior bite turbos, O.B Ch: overbite change, LAFH: lower anterior facial height, S: significant, NS: non-significant

Overbite reduction

Six studies investigated the amount of overbite reduction [12–14, 28–30]. Four of the six studies compared the miniscrew-supported intrusion (MSI) and the Connecticut intrusion arch (CIA) [12, 13, 28, 29]. The pooled estimate showed that the MSI caused a slightly more overbite reduction by 0.36 mm, and the heterogeneity was high (MD= −0.36; 95% CI: −1.06,−0.34; P = 0.31; X² = 11.44; P = 0.01; I² = 74%; Fig. 3A). A leave-one-out sensitivity analysis was conducted to assess the influence of individual studies on the overall results. El Namrawy et al. study showed the greatest influence on heterogeneity. The updated meta-analysis after the exclusion of El Namrawy et al. study also showed that the MSI caused a slightly more overbite reduction by 0.62 mm (MD= −0.62; 95% CI: −1.32, 0.07; P = 0.08; X² = 0.22; P = 0.09; I² = 58%; Fig. 3B), and the heterogeneity decreased to a more acceptable level. According to the GRADE approach, the strength of evidence regarding overbite reduction caused by the MSI compared to the CIA was low (Table 5). One of the six studies compared the lower reversed curve of Spee (RCS) and the anterior bite turbos (ABT) [30]. The two groups had no statistically significant difference regarding overbite reduction (MD= −4.07 mm, MD= −3.87 mm, respectively) [30], and the strength of evidence was moderate (Table 5). The last study compared the utility arch (UA), the J-hook headgear (J-Hg), and the MSI. There was a statistically significant difference in overbite reduction between the MSI and the J-Hg groups (MD= −2.33 mm, MD= −0.8 mm, respectively; p˂0.05). However, there were no significant differences between the MSI and the UA groups (MD= −2.33 mm, MD= −2 mm, respectively) and between the UA and J-Hg groups (MD= −2 mm, MD= −0.8 mm, respectively) [14]; the strength of evidence was low (Table 5).

Fig. 3.

A forest plot illustrating the achieved overbite reduction with miniscrew-supported intrusion compared to the Connecticut intrusion arch. A The original analysis. B After performing a leave-one-out sensitivity test

Table 5.

Summary of the findings according to the GRADE guidelines for included studies

Quality assessment criteria
Comparison	No. of studies	Risk of bias	Inconsistency	Indirectness	Imprecision	Other Considerations	Effect		Relative (95% cl)	Certainty	Comments
							No. of patients	Absolute (95% cl)
Overbite reduction
MSI VS CIA	4 RCTs	Serious	Serious	Not serious	Not serious	None	131	-	Relative effect (Cl 95%): MD −0.36 mm (−1.06, 0.34)	Low ⊕⊕⊖⊖a	The MSI caused a statistically significant decrease in overbite compared to the CIA
MSI VS UA	1 RCTs	Serious	Serious	Not serious	Not serious	None	30	-		Low ⊕⊕⊖⊖a	The difference was statistically insignificant
MSI VS J-Hg	1 RCTs	Serious	Serious	Not serious	Not serious	None	30	-		Low ⊕⊕⊖⊖a	-
UA VS J-Hg	1 RCTs	Serious	Serious	Not serious	Not serious	None	30	-		Low ⊕⊕⊖⊖a	-
RCS VS ABT	1 RCTs	Not serious	Serious	Not serious	Not serious	None	42	-		moderate ⊕⊕⊕⊖a	The difference was statistically insignificant
Upper incisor intrusion
MSI VS CIA	5 RCTs	Serious	Not serious	Not serious	Not serious	None	161	-	Relative effect (Cl 95%): MD −0.77 mm (−1.08, −0.46)	moderate ⊕⊕⊕⊖a	The MSI caused a statistically significant amount of upper incisor intrusion compared to the CIA
MSI VS UA	1 RCTs	Serious	Serious	Not serious	Not serious	None	30	-		Low ⊕⊕⊖⊖a	The difference was statistically insignificant
MSI VS J-Hg	1 RCTs	Serious	Serious	Not serious	Not serious	None	30	-		Low ⊕⊕⊖⊖a	-
UA VS J-Hg	1 RCTs	Serious	Serious	Not serious	Not serious	None	30	-		Low ⊕⊕⊖⊖a	-
RCS VS ABT	1 RCTs	Not serious	Serious	Not serious	Not serious	None	30	-		moderate ⊕⊕⊕⊖a	The ABT caused a statistically significant amount of upper incisor intrusion compared to the RCS
Upper incisor inclination
MSI VS CIA	4 RCTs	Serious	Serious	Not serious	Not serious	None	131	-	Relative effect (Cl 95%): MD 0.63o (−3.18, 4.44)	Low ⊕⊕⊖⊖a	The MSI caused a statistically significant increase in upper incisor inclination compared to the CIA
RCS VS ABT	1 RCTs	Not serious	Serious	Not serious	Not serious	None	42	-		moderate ⊕⊕⊕⊖a	The ABT caused a statistically significant increase in upper incisor inclination compared to the RCS
Lower anterior facial height
MSI VS CIA	4 RCTs	Serious	Not serious	Serious	Not serious	None	131	-	Relative effect (Cl 95%): MD 0.28 mm (−0.48, −0.08)	Low ⊕⊕⊖⊖b	The MSI caused a statistically significant decrease in LAFH compared to the CIA
RCS VS ABT	1 RCTs	Not serious	Serious	Serious	Not serious	None	42	-		Low ⊕⊕⊖⊖a	The ABT caused a statistically significant increase in LAFH compared to the RSC

MSI: miniscrew-supported intrusion, CIA: Connecticut intrusion arch, C: control, J-Hg: J-Hook headgear, UA: utility arch, RCS: reversed curve of spee, ABT: anterior bite turbos, MD: mean difference, RCTs: Randomized Controlled Trials, a: Downgrade one level for risk of bias, and one level due to Inconsistency, b: Downgrade one level for risk of bias, one level due to Inconsistency, and one level for indirectness

Upper incisor intrusion

The amount of upper incisor intrusion was investigated in the eight studies [12–15, 27–30]. Five of the eight studies compared the miniscrew-supported intrusion (MSI) and the Connecticut intrusion arch (CIA) [12, 13, 27–29]. The pooled estimate showed that the MSI caused a slightly more upper incisor intrusion by 0.77 mm, and the heterogeneity among included studies was low (MD= − 0.77; 95% CI: − 1.08, − 0.46; P ˂ 0.00001; X² = 4.87; P = 0.30; I² = 18%; Fig. 4). According to the GRADE approach, the strength of evidence regarding upper incisor intrusion caused by the MSI compared to the CIA was moderate (Table 5). Kahraman et al. also compared the MSI and the CIA. Still, this study was not included in the meta-analysis because it focused on the three-dimensional upper first molar displacement and reported that the MSI and the CIA caused a mean upper incisor intrusion of − 1.46 mm versus − 1.78 mm, respectively [15]. Al-Zoubi and Al-Nimri compared the lower reversed curve of Spee (RSC) and the anterior bite turbos (ABT). The ABT caused a statistically significant amount of upper incisor intrusion compared to the RSC (MD = − 0.43 mm, MD = + 0.02, respectively; P ≤ 0.05) [30]; the strength of evidence was moderate (Table 5). The last study compared the utility arch (UA), the J-hook headgear (J-Hg), and the MSI [14]. Upper incisor intrusion was significantly greater in the MSI group than in the UA and the J-Hg groups (MD = − 2.08 mm, MD = − 1.33 mm; MD= −0.1 mm, respectively). Comparing the UA group and the J-Hg group, the UA group had a significantly greater amount of intrusion (P˂0.001) [14]; the strength of evidence was low (Table 5).

Fig. 4.

A forest plot illustrating the achieved upper incisor intrusion with miniscrew-supported intrusion compared to the Connecticut intrusion arch

Upper incisor inclination

Six studies investigated the upper incisor inclination changes [12, 13, 27–30]. Five of the six studies compared the miniscrew-supported intrusion (MSI) and the Connecticut intrusion arch (CIA) [12, 13, 27–29]. Four of the five studies measured the changes in the angle between the upper incisor and the palatal plane (U1: PP) [12, 13, 28, 29]. The pooled estimate showed that the MSI caused slightly more labial inclination in the upper incisor than the CIA, and the heterogeneity was high (MD = 0.63; 95% CI: − 3.18, 4.44; P = 0.75; X² = 15.52; P = 0.001; I² = 81%; Fig. 5A). A leave-one-out sensitivity analysis was conducted to assess the influence of individual studies on the overall results. El Namrawy et al. study showed the greatest influence on heterogeneity. The updated meta-analysis after the exclusion of El Namrawy et al. study also showed that the MSI caused a slightly more labial inclination in the upper incisor than the CIA, and the heterogeneity decreased to 0% (MD = 2.46; 95% CI: 0.87, 4.42; P = 0.004; X² = 0.29; P = 0.87; I² = 0%; Fig. 5B). According to the GRADE approach, the strength of evidence regarding upper incisor inclination changes caused by the MSI compared to the CIA was low (Table 5). Kumar et al. also compared the MSI and the CIA [27]. However, they measured the changes in the angle between the upper incisor and the anterior cranial base plane (U1: SN). They found that the angle increased in the CIA group and decreased in the MSI group and the difference was statistically significant (MD = + 3.73^o, MD= − 0.93^o, respectively; P ≤ 0.001) [27]. Al-Zoubi and Al-Nimri compared the lower reversed curve of Spee (RSC) and the anterior bite turbos (ABT) [30] and found that the change in the upper incisor inclination in the ABT group was significantly greater than that in the RCS group (MD = + 1.47^o, MD = + 0.37^o, respectively; P ≤ 0.001) [30]; the strength of evidence was moderate (Table 5).

Fig. 5.

A forest plot illustrating the changes in the upper incisor inclination with miniscrew-supported intrusion compared to the Connecticut intrusion arch. A The original analysis. B After performing a leave-one-out sensitivity test

Upper first molar vertical changes

Seven studies examined the vertical changes of the upper first molar [12–15, 27, 29, 30]. Four out of the seven studies compared the miniscrew-supported intrusion (MSI) and the Connecticut intrusion arch (CIA) [12, 13, 15, 27]. There were no statistically significant differences between the two interventions regarding the vertical changes of the upper first molar in all four studies [12, 13, 15, 27]. One study of the seven compared the MSI and the CIA with a third control group of untreated patients [29]. There was a statistically significant extrusion movement of the upper first molar in the CIA group compared to the MSI and control groups (MD = + 0.80 mm, MD = + 0.00 mm, MD = + 0.03 mm, respectively) [29]. In Al-Zoubi and Al-Nimri’s study, there was no statistically significant difference between the anterior bite turbos group (ABT) and the lower reverse curve of Spee (RCS) group regarding upper first molar vertical changes (MD = + 0.08 mm, MD = + 0.05 mm, respectively) [30]. The last study compared the utility arch (UA), the J-hook headgear (J-Hg), and the MSI [14]. There was no statistically significant difference between the MSI and J-Hg groups. However, the utility arch caused a statistically significant extrusion movement of the upper first molar compared to the J-hook headgear and the MSI, which caused a slight intrusion movement (MD = + 0.75 mm, MD = + 0.20 mm, MD= −0.17 mm, respectively) [14].

Lower anterior facial height changes

Five studies examined the lower anterior facial height changes (LAFH) [12, 13, 28–30]. Four of the five studies compared the miniscrew-supported intrusion (MSI) and the Connecticut intrusion arch (CIA) [12, 13, 28, 29]. The pooled estimate showed that the MSI caused a slight decrease in the LAFH compared to the CIA, and the heterogeneity was low (MD= −0.28; 95% CI: −0.48, −0.08; P = 0.007; X² = 0.94; P = 0.082; I² = 0%; Fig. 6). According to the GRADE approach, the strength of evidence regarding LAFH changes caused by the MSI compared to the CIA was low (Table 5). Al-Zoubi and Al-Nimri compared the lower reversed curve of Spee (RSC) and the anterior bite turbos (ABT) [30]. The LAFH increased slightly in the ABT group with a slight decrease in the RCS group (MD = + 0.41 mm, MD= −0.09 mm, respectively; P = 0.002) [30]. The strength of evidence was low according to the GRAGE approach (Table 5).

Fig. 6.

A forest plot illustrating the changes in the lower anterior facial height with miniscrew-supported intrusion compared to the Connecticut intrusion arch

Lower first molar vertical changes/lower incisor angular and linear changes

The angular and linear changes of the lower incisor and the vertical changes of the lower first molar were examined in two studies [29, 30]. In Senışık and Türkkahraman’s study, the MSI caused a slight extrusion of the lower first molar, the CIA caused a slight intrusion, and a slight extrusion happened in the control group (MD = + 0.13 mm, MD= − 0.1 mm, MD = + 0.03 mm, respectively). The lower incisor inclination and extrusion were significantly greater in the MSI and the CIA groups (a mean of + 2.20^o/+0.43 mm versus + 1.20^o/+ 0.23 mm, respectively) compared to the control group (a mean of − 0.10^o/0.00 mm) [29]. However, in Al-Zoubi and Al-Nimri’s study, the lower first molar showed a slightly more extrusion movement in the ABT than in the RCS group (MD = 1.29, MD = + 0.90 mm, respectively). Lower incisor inclination and intrusion were significantly greater in the RCS group than in the ABT group (a mean of + 5.47^o/− 1.01 mm versus + 2.28^o/− 0.28 mm, respectively; P˂0.001) [30].

Discussion

In the current literature, numerous reviews have investigated the effects of miniscrew-supported intrusion, often comparing its efficacy with other orthodontic interventions. However, these reviews predominantly focus on the intrusion effects pertaining to the maxillary incisors. In contrast, our review adopts a comprehensive perspective on bite opening, since opening the bite could happen due to upper or lower incisor intrusion or protrusion, upper or lower molar extrusion, or both.

Bias in the randomization process was a common factor in the six studies that were considered at high risk of bias or at some concerns, due to the lack of information about the randomization methods and the concealment of the allocation. However, bias in the selection of the reported results was the reason why one of the six studies was considered at high risk of bias. As a result, these factors may have affected the level of confidence in these trials and could have weakened the strength of evidence in our systematic review, which is consequently considered to be low.

Six of the eight included studies compared the miniscrew-supported intrusion (MSI) and the Connecticut intrusion arch (CIA) [12, 13, 15, 27–29], one study compared the MSI, J-Hook headgear, and the utility arch [14], and the last study compared the lower reversed curve of Spee (RCS) and the anterior bite turbos (ABT) [30]. Comparing the MSI and the CIA, both interventions were effective in the management of deep bites, with slightly more overbite reduction caused by the MSI compared to the CIA by 0.36 mm, which is clinically insignificant [12, 13, 28, 29]. During the management of deep bites, some changes occur on the incisors and the molars. At the level of the upper incisors, overbite reduction is usually accompanied by intrusion and angular changes. Regarding upper incisor intrusion, both interventions caused a significant amount of intrusion. However, the retrieved studies showed that the MSI caused slightly more upper incisor intrusion than the CIA by 0.77 mm, which is also clinically insignificant [12, 13, 27–29]. Regarding upper incisor inclination, both interventions caused an increase in the inclination of the upper incisor, and according to the conducted meta-analysis of four studies, the MSI caused slightly more increase in the angle between the upper incisor and the palatal plane (U1: PP) [12, 13, 28, 29]. However, the difference was clinically insignificant. On the other hand, Kumar et al. reported the opposite [27]. This can be explained by the fact Kumar et al. studied the angle between the upper incisor and the anterior cranial base (U1: SN); also, they included patients with deep bite and class 2 division 1 malocclusion, which is characterized by a protruded upper incisors, which in turn could have altered the position of the center of resistance of the upper incisors compared to the other studies.

It is important to note that several subgroup analyses presented in this review were not pre-specified in the registered protocol and lacked a clear a priori rationale. Therefore, these analyses should be explicitly considered post-hoc exploratory and interpreted with caution.

At the level of the molars, overbite reduction is usually accompanied by vertical changes. The MSI and the CIA both had no statistically nor clinically significant vertical changes on the upper first molar in four of the six studies [12, 13, 15, 28]. However, Senışık and Türkkahraman reported that the CIA caused a significant extrusion while in the MSI and control groups, there were no vertical changes [29]. This can be explained by the fact that they applied a cinch back on the intrusion arch, which caused less protrusion of the upper incisors compared to the MSI. Still, the reaction represented at the level of the upper first molar, which caused a tip back and extrusion of the molar [29].

Jain et al. compared the MSI, the J-Hook headgear, and the utility arch [14]. The MSI was superior in overbite reduction and upper incisor intrusion compared to the other two interventions. The utility arch was also effective in overbite reduction, but to a lesser extent than the MSI and to a greater extent than J-Hook headgear. Overbite reduction caused by the utility arch was due to upper incisor intrusion and upper molar extrusion, which was significant compared to the other two interventions. Since it depends on patient cooperation, the J-Hook headgear caused a lesser amount of overbite reduction and upper incisor intrusion than the other two interventions [14]. Al-Zoubi and Al-Nimri compared the lower reversed curve of Spee (RCS) and the anterior bite turbos (ABT) [30]. Both interventions reduced the overbite significantly, with slightly more overbite reduction in the RCS group than in the ABT group. However, the effective treatment lasted until a desirable amount of overbite correction was reached, and the ABT took less time than the RCS. Comparing the two interventions, reducing the overbite with the ABT was accompanied by a significant amount of upper incisor intrusion and protrusion. In contrast, a significant amount of lower incisor intrusion and protrusion accompanied the RCS. This can be attributed to the occlusal forces applied by the mandible on the upper incisors in the ABT group and the forces that the lower reversed curve of spee archwire applied on the lower incisors. Neither intervention caused significant vertical changes on the upper first molar. However, the lower first molar was extruded in both groups, with a statistically significant extrusion in the ABT group than in the RCS. This can be explained by the posterior occlusal gap that the ABT creates, which allows more extrusion [30].

The lower anterior facial height (LAFH) was not significantly affected by the MSI, CIA, ABT, and RCS [12, 13, 28–30]. Some of these interventions decreased the LAFH and some increased it, but the change did not reach 1 mm, which is probably below the clinical significance threshold.

An important consideration in deep bite treatment is the influence of growth, particularly in adolescent patients. The vertical dimension matures later in craniofacial development, meaning the treatment response in adolescents may differ significantly from that in adults [2]. According to Diouf et al., growth modulation in adolescents leads to skeletal changes that improve treatment stability and support more effective deep bite correction. In contrast, adult patients lack the advantage of growth modulation, so their treatment depends solely on dentoalveolar changes, and these are prone to relapse [11].

There are no specific details about the effect of the utility arch and the J-Hook headgear on the LAFH since Jain et al. did not assess this variable in their study [14].

Limitations of the current work

The current review was limited by the small number of interventions evaluated across multiple studies, which restricted our ability to perform meta-analysis beyond miniscrew-supported intrusion and the Connecticut intrusion arch. Variability in outcome definitions and radiographic assessment methods (including periapical radiographs, lateral cephalograms, and CBCT) posed challenges for data synthesis and may have introduced measurement bias. Moreover, only two of the eight included studies were assessed as having low risk of bias, reducing confidence in the pooled estimates. In particular, concerns regarding randomization procedures were noted in several studies, which may have introduced selection bias and affected internal validity. Most studies lacked control groups, and follow-up periods were insufficient to evaluate long-term stability or relapse. These methodological shortcomings in the available evidence, combined with constraints in the synthesis process, limit the strength and generalizability of the findings.

Conclusions

Implications for practice

Based on the available data, several interventions appear to be effective in managing the deep bite problem. The MSI consistently demonstrated slightly greater upper incisor intrusion and overbite reduction compared to other techniques; however, the differences between these interventions were below the clinical threshold. Conversely, the J-Hook headgear demonstrated the least efficacy among the evaluated interventions, producing the smallest overbite reduction and upper incisor intrusion. Nevertheless, as the overall certainty of evidence—assessed using the GRADE approach—ranged from low to moderate, particularly due to concerns about risk of bias and inconsistency, these findings should be interpreted with caution.

Implications for research

Given that the quality of evidence of the reported outcomes ranged from low to moderate, and the high risk of bias in six of the eight studies, further high-quality RCTs are needed to strengthen the evidence on deep bite treatment in adults and adolescents. Since our meta-analysis was limited to direct comparisons between two appliances, future research should consider a Network Meta-Analysis to integrate both direct and indirect comparisons, providing a more comprehensive evaluation of available therapeutic approaches.

Abbreviations

MSI

Miniscrew-supported intrusion

CIA

The Connecticut intrusion arch

UA

The utility arch

J-Hg

The J-Hook headgear

ABT

Anterior bite turbos

RCS

Reversed curve of Spee archwire

LAFH

Lower anterior facial height

Author contributions

OAR and MYH individually conducted literature searches, reviewed articles’ full-texts, identified suitable studies for inclusion, extracted and organized data, evaluated potential biases, performed both qualitative and quantitative analyses, and collaboratively drafted the initial versions of this manuscript. In addition, MYH played a key role in formulating the focused review question. MKA mediated disagreements that arose during study selection and bias assessment, and meticulously editing the final draft of the manuscript. STJ, JMK, SJ helped in data entry, data analysis, results’ interpretation, and writing the first drafts of this manuscript. The final version of this manuscript was read and approved by all authors.

Funding

All authors have stated that they did not receive any financial support from any organization for the work submitted.

Data availability

The datasets utilized and/or analyzed in this review can be obtained from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

Not applicable.

Competing interests

The authors declare no competing interests.