Comparison of changes in nasal cavity and maxillary sinus volumes after facemask treatment with or without expansion in class III maxillary deficiency subjects

Abstract

Introduction

This study was designed to evaluate and contrast the volumetric changes occurring within the nasal cavity (NC) and maxillary sinuses (MS) in patients during growth periods with Class III malocclusion, treated with either face mask (FM) or FM with rapid maxillary expansion (RME) treatment, utilizing cone beam computed tomography (CBCT).

Materials and methods

Pre-treatment (T0) and post-treatment (T1) cone beam computed tomography scans of 38 growing Class III patients (21 females, 17 males) treated with FM and FM/RME were determined and allocated into two groups: The FM/RME (11 females, 8 males; mean age, 11.71 ± 1.145 years) and the FM group (10 females, 9 males; mean age, 11.75 ± 1.021 years). The volumes of NC, right maxillary sinus (R-MS), left maxillary sinus (L-MS) and total maxillary sinus (T-MS) were measured at two time points: T0 and T1.

Results

At the beginning of treatment(T0), there was no difference in the volumes of NC, R-MS, L-MS, T-MS in both FM and FM/RME groups. Both groups (FM/RME and FM) showed statistically significant increases in all volumetric measurements (NC, R-MS, L-MS, T-MS). In the comparison between the groups, a statistically significant difference was observed only in the NC measurement, while no significant differences were found in the other measurements (MS, L-MS, T-MS).

Conclusions

Both FM and FM/RME are effective treatment modalities for increasing NC and MS volumes. FM/RME is a more effective treatment protocol for increasing NC volume.

Introduction

Skeletal Class III malocclusion, which can be challenging to treat due to unpredictable skeletal growth and treatment outcomes, may be associated with mandibular protrusion, maxillary retrusion or a combination of both conditions [1]. Treatment options for individuals skeletal Class III malocclusions may vary depending on the jaw from which the problem originates, the severity of the anomaly, age, patient expectations, and growth & development potential [2].

The application of FM for maxillary protraction, either combined with RME or used alone is common approach in the treatment of skeletal Class III malocclusion associated with maxillary deficiency in growing children. Despite the documented effects of FM/RME on the skeletal, dental and soft tissue structures, there is a paucity of studies evaluating the volume of the NC and MS in growing Class III patients. However, Several studies have investigated the impacts of FM/RME on the pharyngeal airway, quite few studies have examined and compared the changes in the volume of the NC and MS after RME and/or FM [3].

It has been reported that the incidence of upper airway obstruction is high in skeletal Class III patients characterized by maxillary developmental insufficiency and that early treatment of the upper jaw in sagittal and transversal directions will positively affect the dimensions of the upper airway [4]. The changes provided by various treatment protocols in skeletal Class III anomalies caused by maxillary underdevelopment are mostly examined with cephalometric studies [5]. Although the information obtained from cephalometric studies, which allow only two-dimensional (2d) examination of three-dimensional (3d) structures and the changes occurring in these structures, is important, it is not sufficient and its accuracy is controversial [6]. Unlike the pharyngeal airway, the NC and MS, which are surrounded by hard tissues, have been measured in very few previous studies and the majority of these studies have evaluated these 3 d structures with conventional lateral cephalograms [7]. Although there are more studies evaluating the NC, which is known to be affected by various orthopedic treatment methods such as RME and/or FM, with different measurement methods and boundaries in 3D methods, there are very few studies evaluating the NC and MS volume together [3]. Therefore, the objective of this retrospective study was to assess and compare the volumetric changes in the NC and MS between FM and FM/RME groups and within each group after protraction facemask treatment with or without RME in growing Class III patients using CBCT.

Materials and methods

This retrospective study was approved by the Harran University Clinical Research Ethics Committee. (HRU/24.16.52) The requirement for informed consent was waived by the committee due to the retrospective nature of the study, and because all data were anonymized and evaluated in accordance with national ethical guidelines. The study records were selected from the CBCT of 38 patients (17 girls,21 boys) treated with FM or FM/RME in the orthodontic department at the beginning (T0) and end of treatment (T1). This retrospective study utilized available data. The adequacy of the sample size was evaluated in light of literatüre [8]. A post-hoc power analysis was performed due to the retrospective nature of the study. Based on the observed results, Cohen’s d was calculated, and with 19 patients in each group, the analysis confirmed that a sufficient statistical power was achieved to detect the observed differences. The demographic data of both treatment groups are presented in Table 1. Inclusion criteria were as follows: CBCT records from before treatment and after FM or FM/RME, patients with skeletal Class III malocclusion (ANB angle less than 0°, Wits appraisal less than − 2 mm) caused by maxillary deficiency SNA less than 78, normal vertical development, active growth & development according to the vertebral maturation method, age between 9 and 14 years. The exclusion criteria are as follows: Previous ortodontic treatment, any systemic disease, congenital/craniofacial deformity such as cleft lip and palate, and temporomandibular disorders (TMD), history of anedneidectomy/tonsillectomy, history of systemic conditions potentially affecting bone metabolism.

All images at pretreatment (T0) and posttreatment (T1) were obtained using the Castellini X-Radius Trio -Plus (Italy) CBCT machine The imaging parameters included 90 kVp, 8 mA, a 13 cm × 16 cm field of view, 0.2 mm voxel size, 1 mm slice thickness, and a 12-second scan time. A total of 76 CBCT images from 38 patients were saved in Digital Imaging and Communication in Medicine (DICOM) format and these data were uploated to the Dolphin 3D (Dolphin Imaging & Management Solutions, Version 11.9, Chatsworth, California, USA) to obtain a 3 d reconstruction image. The time interval between the start of treatment and the T1 acquisition was retrospectively evaluated for both treatment groups. For the RME + Facemask group, the mean duration of treatment was 7.07 ± 0.54 months, while for the Facemask only group, it was 6.96 ± 0.50 months. Statistical analysis revealed no significant difference between the two groups (p > 0.05), indicating comparable follow-up durations for volumetric measurements. This consistency supports the reliability of post-treatment evaluations across both groups. All CBCT images, at both T0 and T1, were oriented using the skeletal midline, the Frankfort horizontal plane, and a line connecting the inferior rims of the left and right orbits, utilizing the “Orientation” option. The volumetric values of the nasal cavity, left and right maxillary sinuses were individually measured at T0 and T1 by selecting the appropriate Hounsfield Unit scale band range. In the Hounsfield Unit (HU) scale, which is used to separate tissues of different densities from each other, the sinuses and air spaces are separated from each other according to the density of soft and hard tissues. In our study, segmentation of the airway of each individual was performed using the same HU value range in T0 and T1 measurements through Dolphin 3D Sinus/Airway volume analysis software for each scan. After orientation, the borders of the nasal cavity/maxillary sinuses were determined separately with green colored lines from the “Sinus/Airway” tab of the software in the sagittal, axial and coronal views by visual inspection individually, and yellow seed points were located within the relevant region and boundaries ensuring the entire sinus was encompassed. The volumetric measurements of the nasal cavity (NC) and maxillary sinuses (MS) were conducted using Dolphin 3D software (Dolphin Imaging & Management Solutions, Version 11.9, Chatsworth, California, USA) on CBCT scans obtained before (T0) and after treatment (T1). During the segmentation process, anatomical boundaries were carefully delineated in the sagittal, axial, and coronal planes. For the NC, the defined borders included the anterior nasal spine (ANS), posterior nasal spine (PNS), tip of the nasal bone (TNB) and sella (S) (Fig. 1).

Fig. 1.

Boundaries and volume measurements of NC used in this study

The segmentation of the maxillary sinuses was performed separately on sagittal midline sections at the level of the maxillary first molar furcation, accurately tracing the superior, inferior, medial, and lateral walls. The same method was applied to coronal sections, focusing on the widest dimension of each sinus to ensure comprehensive volume representation (Fig. 2). This approach provided reliable and reproducible volumetric measurements across both time points. After the nasal cavity and the right and left maxillary sinuses were segmented, the volumes were semi-automatically calculated in mm³ by clicking the “Update Volume” tab. This action turned the radiolucent area pink. The total maxillary sinus volume was calculated by adding the left and right volume measurements together [9, 10] The boundaries and parameters utilized in this study to measure NC and MS volumes are shown in Fig. 1 (NC) and Fig. 2 (MS).

Fig. 2.

Boundaries and volume measurements of MS (R- MS) used in this study

The Hyrax screw (Leone, Sesto Fiorentino, Italy) was used in the treatment, and each quarter turn of the screw provided a 0.25 mm expansion. In the RME/FM group, parents were instructed to activate the Hyrax disjunctor appliance twice a day (0.5 mm/day) for the first week after its cementation with the buccal hook appliance. Protraction facemask (FM) treatment began when diastema appeared in each patient. The RME appliance was kept in place until the FM treatment was completed. The Hyrax screw was activated two turns per day (0.25 mm per round) until the desired enlargement of the transverse relationships is achieved (for seven to 21 days). The Petit-type FM was adapted to the face and protraction force range 400 to 500 g was applied on each side with elastics elastic (force vector) directed 30–45° downward relative to the occlusal plane. Patients were instructed to use the FM for at least 16–18 h a day (excluding eating and sports activities) and controlled with one-month appointments. The treatment was continued for approximately 6 months until a 3–5 mm overjet and convex profile was obtained with Class II relationship in the molar and canine teeth with overcorrection. In the group in which only FM was applied, Petit type FM was applied with the same protocol.

Statistical analyses were performed to evaluate the volumetric changes in the nasal cavity and maxillary sinuses between treatment groups. Initially, the normality of the data distribution was assessed using the Shapiro-Wilk test. Based on the results, parametric tests were applied to normally distributed variables, while nonparametric tests were utilized for variables that did not meet normality assumptions. Changes between T0 and T1 within each group were analyzed using paired t-tests or Wilcoxon signed-rank tests as appropriate. Additionally, delta values (T1-T0) representing volumetric changes were calculated and compared between the two treatment groups using an independent samples t-test or Mann-Whitney U test, depending on the distribution of the data. The demographic distribution of the participants was assessed using the chi-square test. All statistical analyses were performed using SPSS software (version 20), with a significance level set at p < 0.05.

Results

In our study, the demographic variables, including age, gender, and treatment duration of all patients at the beginning of treatment (T0), were analyzed, and no statistically significant differences were found between the two groups, ensuring the comparability and homogeneity of the sample. Additionally, there were no initial differences between the groups in the volumetric measurements of the nasal cavity (NC), right maxillary sinus (R-MS), left maxillary sinus (L-MS), and total maxillary sinus (T-MS) at T1. This finding indicates that both groups started with similar baseline characteristics in terms of craniofacial and sinus anatomy.

When the two groups were compared, a statistically significant difference was observed only in the NC volume, with the FM/RME group showing a greater increase than the FM group.(Table 1) This finding highlights the superior effectiveness of the FM/RME protocol in expanding the nasal cavity. However, no significant differences were found between the two groups in the changes observed in the maxillary sinuses (R-MS, L-MS, and T-MS). These results indicate that while both treatment modalities are effective for volumetric enhancement, the FM/RME combination offers additional benefits specifically for nasal cavity expansion.

Table 1.

Intergroup comparisons

Variable	RME/FM Mean ± Std.Dev	FM Mean ± Std.Dev	P value
Treatment Duration	78,41 ± 1,47	78,51 ± 1,52	,838*
ANB	−2,46 ± 1,07	−2,36 ± 1,11	,780*
SNA	75,47 ± 0,30	76,21 ± 0,24	,258**
SNB	78,37 ± 0,32	78,47 ± 0,31	,729**
Nasal Cavity t1	21,094 ± 6394	19,849 ± 5331	,518*
Nasal Cavity t2	22,702 ± 6925	20,759 ± 5480	,344*
Nasal Cavity Δ	1607 ± 254	909 ± 145	,032**
Right Maksillary Sinus t1	10,567 ± 846	10,614 ± 465	,506**
Right Maksillary Sinus t2	10,933 ± 841	10,849 ± 491	,644**
Right Maksillary Sinus Δ	366 ± 287	234 ± 243	,136*
Left Maksillary Sinus t1	10,280 ± 795	10,874 ± 510	,212**
Left Maksillary Sinus t2	10,669 ± 772	11,087 ± 537	,284**
Left Maksillary Sinus Δ	388 ± 78	213 ± 70	,080**
Total Maksillary Sinus t1	20,848 ± 1626	21,489 ± 968	,271**
Total Maksillary Sinus t2	21,602 ± 1601	21,936 ± 1023	,452**
Total Maksillary Sinus Δ	754 ± 557	447 ± 117	,086*

* Independent Samples Test

**Mann-Whitney U Test

Following treatment, both groups demonstrated volumetric increases in all parameters. Notably, the RME/FM group showed a significantly greater increase in Nasal Cavity (NC) volume compared to the FM group (ΔNC: 1607 ± 254 mm³ vs. 909 ± 145 mm³, p = 0.032), as detailed in Table 2. However, no significant intergroup differences were observed for Right Maxillary Sinus, Left Maxillary Sinus, and Total Maxillary Sinus volumes (p > 0.05).

Table 2.

Intragroup comparisons

Table 1: Demografic variables for Groups
Demografic variables	Groups				P value
	RME/FM		FM
Gender	Female	Male	Female	Male	0,744*
	11 (%57.89)	8 (%42.11)	10 (%52.63)	9 (%47.37)
Age	Mean ± Std.Dev.		Mean ± Std.Dev.		0,905**
	11,71 ± 1,14		11,75 ± 1,02

* Chi-square Test

** Independent Samples T Test

Table 3.

However, no significant intergroup differences were observed for Right Maxillary Sinus, Left Maxillary Sinus, and Total Maxillary Sinus volumes (p >0.05).

Variable	RME/FM		FM
	Mean ± Std.Dev	P value	Mean ± Std.Dev	P value
Nasal Cavity t1	21,094 ± 6394	,000*	19,849 ± 5331	,000*
Nasal Cavity t2	22,702 ± 6925		20,759 ± 5480
Right Maksillary Sinus t1	10,567 ± 846	,000*	10,614 ± 465	,001*
Right Maksillary Sinus t2	10,933 ± 841		10,849 ± 491
Left Maksillary Sinus t1	10,280 ± 795	,001**	10,874 ± 510	,007*
Left Maksillary Sinus t2	10,669 ± 772		11,087 ± 537
Total Maksillary Sinus t1	20,848 ± 1626	,000**	21,489 ± 968	,001*
Total Maksillary Sinus t2	21,602 ± 1601		21,936 ± 1023

* Paired Samples t Test

**Wilcoxon signed-rank test

Both treatment protocols, FM/RME and FM alone, led to statistically significant increases in all volumetric parameters (NC, R-MS, L-MS, T-MS) after treatment. The intragroup analysis revealed statistically significant volumetric increases for Nasal Cavity (p = 0.000), Right Maxillary Sinus (p = 0.000 for RME/FM, p = 0.001 for FM), Left Maxillary Sinus (p = 0.001 for RME/FM, p = 0.007 for FM), and Total Maxillary Sinus (p = 0.000 for RME/FM, p = 0.001 for FM) in both groups. These results highlight the effectiveness of both FM and RME/FM treatments in enhancing maxillary and nasal cavity volumes.

All volumetric measurements were carried out by a single examiner who was blinded to the group allocations during the analysis process to prevent potential bias. To ensure reliability and consistency of the measurements, 20 randomly selected CBCT scans were remeasured at two-week intervals by the same investigator. This repeated evaluation allowed for the assessment of intraobserver reliability, which was measured using Dahlberg’s formula (S = √∑d²∕2n) for random error calculation. Systematic errors were evaluated with a paired t-test at a significance level of p < 0.05. The intraclass correlation coefficients (ICCs) ranged from 0.85 to 0.98, indicating high reliability and consistency across all volumetric parameters [11, 12].

Discussion

Aesthetic and functional problems caused by skeletal Class III anomalies lead patients to seek treatment. Morphologically, skeletal Class III malocclusions may consist of underdevelopment and/or retrusion of the maxilla, true mandibular overdevelopment (mandibular prognathia) or a combination of these [1]. Determining the dental and skeletal components of skeletal Class III malocclusion directly affects the type and timing of treatment.

Maxillary protraction face mask (FM) with or without RME is widely used for early intervention of children presenting skeletal Class III malocclusion associated with maxillary deficiency [13, 14]. The effects of RME and FM treatment on craniofacial structures have been examined in many studies on different sample groups and the dental, skeletal and soft tissue changes have been extensively revealed [15]. However, the lack of information available in the orthodontic literature concerning the changes in the size and structure of the NC and MS caused by these treatments reveals the need for a more comprehensive examination of these changes [16].

Changes in the respiratory tract due to growth & development and orthodontic treatment approaches have long been of interest to orthodontists [17]. Many studies have focused on investigating the association between pharyngeal and craniofacial structures [18]. In growing Class III patients, retrognathic or insufficient maxillae are expected to impact upper airway development, including the paranasal sinuses such as MS, NC and pharyngeal airway. Skeletal Class III malocclusion resulting from maxillary deficiency is also closely related to the individual’s breathing pattern and the capacity of the pharyngeal airway [19].

Fundamental orofacial functions such as respiration, mastication, and deglutition play a critical role in the proper growth and development of the jaw bone. Mouth breathing results in a lower resting position of the tongue within the oral cavity, which subsequently alters the equilibrium of muscular forces between the orofacial muscles and the tongue, in contrast to children who exhibit nasal breathing patterns. The nasal cavity and paranasal sinuses form a functional unit as well as an integral part of the respiratory tract. The maxillary sinuses are air-filled cavities that occupy the largest space in the human skull among the paranasal sinuses, but thanks to their special epithelium, they have important effects on improving the nasal respiratory function by supporting the immune defense of the nasal cavity [20, 21].

NC and MS volume has been previously assessed using 2 d lateral and antero-posterior radiographs, computer tomography (CT) and acoustic rhinometry [22]; nevertheless, many of these techniques fail to provide accurate measurement of maxillary and nasal sinus volume. However, studies examining changes in the NC and MS after FM treatment with or without RME are very limited and previous studies have measured these 3 d structures mainly in two dimensions [5, 7].

In order to detect volumetric changes in the nasopharyngeal airway and maxillary sinuses with high sensitivity, methods that can provide 3 d analysis and measurement, such as CT, CIBT, and magnetic resonance imaging (MRI), have been reported to be more reliable [6]. MRI has the disadvantages that swallowing causes artifacts in the image due to long working time and is expensive. Due to the disadvantages of CT, such as more radiation to the patient and longer scan time compared to CBCT, CBCT is preferred for imaging of the craniofacial region for diagnostic assessment and treatment planning. In addition to its advantages such as low cost, low radiation level and ease of application, CBCT is a highly precise and reliable imaging technique for 3 d evaluation of the respiratory tract and paranasal sinuses [23]. Weissheimer et [24] evaluated the accuracy and reliability of various software for 3 d analysis of the upper airway and reported that the Dolphin 3D software we used was one of the most reliable software with a 1% error rate.

The fact that there was no statistical discrepancy when airway parameters at the beginning of treatment were compared indicates the homogeneity of both groups in the study subjects. In our study, a statistically significant difference was found in each volumetric measurement (NC, R-MS, L-MS, T-MS) in both groups. In skeletal Class III children, skeletal changes obtained with orthopedic treatments have been reported to change airway dimensions with the adaptation of hard and soft tissues in adjacent anatomical structures [7]. FM and/or RME applications may affect not only the upper jaw but also the NC and MS dimensions directly or indirectly due to their anatomical neighborhood. Liu at al. [3] reported a significant increase in NC, nasopharyngeal and maxillary sinus volumes in both groups in their evaluation of CBCT records of patients who underwent FM/RME and FM/Alt-RAMEC. However, it can be said that our findings are compatible even though the treatment methods applied are not completely the same. While the same investigators did not find any difference in any volumetric measurements between the groups, in our study, only a statistically significant change in NC was found in the FM/RME group compared to the FM group. It is thought that some methodologic differences and incompatibility in age groups may be responsible for the discordance between the findings of this study and our findings.

Ghoreishian and Gheisari [25] reported in their rhinomanometric study that intranasal resistance decreased and airflow increased and respiratory function improved in patients who underwent maxillary advancement with Le Fort I osteotomy. Although we applied a different method with the investigators, it can be said that the significant increase in NC volume as a result of maxillary advancement due to FM treatment in our study is in parallel with the findings of these investigators. Mucedero et al. [7]examined the effect of RME4FM and FM use on sagittal pharyngeal dimensions in comparison with a control group and reported that, contrary to our findings, maxillary and mandibular skeletal changes provided by maxillary advancement with and without RME did not cause a significant increase in sagittal nasopharyngeal dimensions and did not result in a significant change in airway dimensions compared to untreated skeletal Class III individuals. When studies evaluating the effects of different FM procedures on nasopharyngeal airway and MS volume are examined, it can be said that increases similar to our findings were recorded [25–27]. However, when many factors such as differences in the amount of movement and direction of movement in the upper and lower jaws and in the interjaw relationship, duration of treatment, age and gender distribution of the individuals included in the study, low sample sizes and individual differences are added to the differences in the treatment methods applied, the issue may become more complex and the reliability and accuracy of the results may be controversial. Inconsistent findings regarding changes in NC and MS size may be due to variations in the ethnic backgrounds of the study population, differences in treatment protocols, treatment duration, the extent of anterior maxillary movement, as well as the 2D and 3D methodologies and software utilized to perform segmentation and measurements of the airway and sinus regions.

Although the positive effects of RME on nasopharyngeal airway and MS have been reported in many studies, the effects of FM with and without RME are not fully known [28–30]. The Hyrax disjunctor appliance, employed in our study to widen the palatine suture in young patients, has also been reported to induce an increase in the NC and MS complex [27]. In this context, changes in the nasal cavity have been suggested to play a role in the development of obstructive sleep apnea [31], with studies even indicating that a decrease in maxillary sinus volume may serve as a predictive factor for obstructive sleep apnea. Wertz et al. [32] demonstrated that although RME procedures are not specifically recommended to improve overall airflow, they can increase nasal airflow in patients with nasal airway stenosis. A systematic review and meta-analysis focusing on three-dimensional evaluations [33] concluded that RME has a beneficial short-term effect on enhancing the volume of the nasal cavity and the upper part of the pharyngeal airway. In our study, the statistically significant difference in the volume of the NC only in the FM/RME group compared to the FM group in the intergroup comparison supports the positive effects of RME on the NC. On the other hand Smith et al. [8] reported no significant alteration in MS volume after RME in growing children in their study on CBCT records. Kavand et al. [34] reported a significant increase in NC width after RME in adolescent patients, but no significant change in MS volume. While there was a parallelism between the results of these studies and our study in terms of the increase in nasal cavity width, differences were observed in terms of changes in maxillary sinus volume. It is thought that these differences may be due to the age of the patients, the treatment method applied and the differences in the measurement technique of the maxillary volume.

With orthopedic or orthognatic treatment approaches, significant changes can be achieved in the pharyngeal soft tissues, tongue and hyoid bone, especially in the bony structures surrounding the upper respiratory tract. As a result of these changes, a significant increase in respiratory capacity can be achieved. The posterior positioning of the maxilla is especially important in OSA, as it causes the tongue and soft palate structures to be located in a more posterior position, leading to narrowing of the pharyngeal airway. FM/RME therapy reduces the resistance of the airway, facilitating inspiratory airflow and may alleviate OSA symptoms [35–37]. In this context, orthodontics plays a role in the multidisciplinary approach to treating individuals with maxillary deficiency by achieving skeletal expansion, resolving posterior crossbite, correcting the position of the tongue and soft palate through oral expansion, and reducing mouth breathing to address naso-respiratory issues. Maxillary insufficiency contributes to the development of OSAS by reducing the dimensions of the upper airway and causing a lower positioning of the tongue. RME has been proposed as a potential adjunctive treatment for children with OSAS due to its positive effects on respiration. However, the role of maxillary protraction remains insufficiently elucidated [38].

Our findings demonstrated that both treatment modalities resulted in a significant increase in NC and MS volumes; however, the increase in NC volume was more pronounced in the FM/RME group. This outcome supports the positive impact of maxillary expansion on the nasal airway. Our results suggest that upper airway constriction associated with maxillary deficiency may be reversible through orthopedic treatment approaches such as FM and/or RME and that these methods may play a potential role in the management of respiratory disorders, including OSAS. In this context, a more detailed evaluation of changes in nasal and maxillary sinus volumes highlights that orthopedic treatment approaches such as FM and RME may contribute not only to skeletal correction but also to functional improvement of the upper airway. Considering that orthodontic treatments, particularly when applied during the growth period, may have lasting effects on respiratory function, the integration of such approaches into multidisciplinary treatment protocols is of significant importance.

This study presents certain limitations, including a relatively limited sample size, the absence of an untreated Class III control group due to ethical constraints, and the retrospective nature of the study design, which inherently influences both treatment and sample selection processes. Ethical considerations prevent the inclusion of untreated control groups in retrospective studies, as withholding treatment from growing Class III patients may compromise their skeletal development and respiratory health. To mitigate this limitation, we matched the two study groups based on CBCT records of Class III patients, ensuring similarity in skeletal age, gender, and the severity of skeletal malocclusions. Our investigation focused on evaluating the effects of the two treatment protocols (FM and FM/RME) on changes in NC and MS volumes from baseline to post-treatment. To enhance the generalizability and robustness of the findings, future research should consider prospective, randomized clinical trials with larger cohorts and untreated control groups, which would allow for more comprehensive evaluation of natural growth patterns alongside treatment effects. Moreover, the use of CBCT imaging not only reduced radiation exposure compared to traditional methods but also provided detailed volumetric analysis, supporting the reliability of our findings.

Conclusions

This study provides valuable insights into the volumetric changes in NC and MS following FM treatment with or without RME in growing Class III patients. Both treatment modalities significantly increased NC and MS volumes, underscoring their effectiveness in addressing maxillary deficiencies. However, the FM/RME protocol demonstrated a more pronounced effect on NC volume compared to FM alone, highlighting the added benefits of RME in expanding nasal airflow pathways. These findings suggest that both approaches are effective, but FM/RME offers a superior protocol for enhancing NC volume. Future studies with larger sample sizes and a focus on evaluating respiratory improvements not only in terms of volumetric changes but also functional outcomes are necessary to further support these conclusions.

Authors’ contributions

All manuscript wroten by one author: Mevlude Yuce Polat.

Funding

This research received no external funding.

Data availability

The dataset supporting the conclusions of this article is available from the corresponding author, Dr. Mevlude Yuce Polat (email: drmevludepolat@gmail.com), upon reasonable request.

Declarations

Ethics approval and consent to participate

The study was conducted in accordance with the Declaration of Helsinki and approved by the Clinical Research Ethics Committee of Harran University with a protocol code HRU/24.16.52. The requirement for informed consent was waived by the committee due to the retrospective nature of the study, and because all data were anonymized and evaluated in accordance with national ethical guidelines.

Consent for publication

This manuscript does not contain any individual person’s data in any form that.

Competing interests

The authors declare no competing interests.