Miniscrew-assisted rapid palatal expansion for managing arch perimeter in an adult patient

Short-term outcomes in the upper airway with tooth-bone-borne vs bone-borne rapid maxillary expanders

BACKGROUND

This study compared the area and minimal section of the nasal cavity, nasopharynx, oropharynx, and hypopharynx in cases treated with different methods of microimplant-assisted expansion.

METHODS

Based on a pilot study to calculate the sample size, 30 patients with transverse maxillary deficiency over 14 years of age were retrospectively selected. These patients had received two different types of microimplant-assisted maxillary expansion treatment (MARPE and BAME). The patient underwent Cone-Beam computed tomography (CBCT) before and after treatment (mean time 1.5 months) with MARPE or BAME and upper airway measurements (volume and minimum cross-sectional area) were taken to assess upper airways changes and compare changes between the groups. A paired sample t-test was performed to evaluate the T0-T1 change of airway measurements obtained with MARPE and BAME, and a student t-test to compare changes in airway measurements between MARPE and BAME.

RESULTS

This investigation shows a statistically significant increase in total nasopharyngeal airway volume (0.59 ± 1.42 cm3; p < 0.01), total oropharyngeal airway volume (3.83 ± 7.53 cm3; p < 0.01) and minimum oropharyngeal cross-section (53.23 ± 126.46 mm2; p < 0.05) in all cases treated with micro-screw assisted expansion. The minimal cross-sectional area of the oropharynx ((79.12 ± 142.28 mm2; p < 0.05) and hypopharynx (59.87 ± 89.79 mm2; p < 0.05) showed significant changes for cases treated with BAME. As for the comparison between cases treated with MARPE and BAME, no differences in upper airway changes have been observed, except for the minimum cross-sectional area of the nasal cavity, which increases for MARPE (52.05 ± 132.91 mm2) and decreases for BAME (-34.10 ± 90.85 mm2).

CONCLUSIONS

A significant increase in total area and minimal section at the level of nasopharynx and oropharynx was observed in cases treated with BAME. Regarding the comparison of MARPE and BAME treatments, no differences were found in the total airway volume and minimal section in upper airway except for the minimum cross section of the nasal cavity that increases for MARPE and decreases for BAME.

Midpalatal Suture Maturation Stage in 10- to 25-Year-Olds Using Cone-Beam Computed Tomography-A Cross-Sectional Study

In this study, we aimed to evaluate the frequency of midpalatal maturational stages in a Chilean urban sample of adolescents, post-adolescents and young adults, associated with chronological age and sex, by assessing CBCT scan images. Tomographic images in axial sections of the midpalatal sutures from 116 adolescents and young adults (61 females and 55 males, 10-25 years old) were classified according to their morphologic characteristics in five maturational stages (A, B, C, D and E), as proposed by Angelieri et al. The sample was divided into three groups: adolescents, post-adolescents and young adults. Three previously calibrated examiners (radiologist, orthodontist and general dentist) analyzed and classified the images. Stages A, B and C were considered to be an open midpalatal suture, and D and E were considered to be a partially or totally closed midpalatal suture. The most frequent stage of maturation was D (37.9%), followed by C (24%) and E (19.6%). The possibility of finding closed midpalatal sutures in individuals of 10 to 15 years was 58.4%, and in subjects aged 16 to 20 and 21 to 25 years, it was 51.7% and 61.7%, respectively. In males, Stages D and E were present in 45.4%; for females, this prevalence was 68.8%. Individual assessment of the midpalatal suture in each patient is of crucial importance before making the clinical decision of which is the best maxillary expansion method. Due to the extensive calibration and training required, it is advisable to always request a report from a radiologist. Individual evaluation with 3D imaging is recommended because of the great variability observed in the ossification of midpalatal sutures in adolescents, post-adolescents and young adults.

Midpalatal Suture Maturation Method for the Assessment of Maturation before Maxillary Expansion: A Systematic Review

Assessment of midpalatal suture maturation is crucial before deciding which type of maxillary expansion technique will be performed to treat transverse discrepancies. In 2013, Angelieri et al. proposed a new method to evaluate midpalatal maturation using cone-beam computed tomography. The aim of this study was to systematically identify, evaluate, and provide a synthesis of the existing literature about this new method and to rigorously assess the methodological quality of these articles. A bibliographic search was carried out using PubMed, Cochrane Library, SciELO, LILACS, Web of Science, and Scopus using the terms midpalatal suture, cranial sutures, palate, maturation, interdigitation, ossification, maxillary expansion, evaluation, assessment, and assess. Quality assessment was performed using the Observational Cohort and Cross-Sectional Studies tool developed by the National Heart, Lung, and Blood Institute. Hence, 56 articles were obtained, of which only 10 met the selection criteria. We could not include any of the data into an analysis because of the large variation of the data collected and high methodological heterogeneity found among studies. Of all the studies included, 10% had poor quality, 70% fair, and 20% good quality, respectively. Even though age and sex play a role in midpalatal suture obliteration, there is a poor correlation between these variables. Thus, every patient should be assessed individually before choosing the best protocol for maxillary expansion. The midpalatal suture maturation method has the potential to be used for diagnostic purposes, but clinicians should be cautious of routinely using it because an extensive training and calibration program should be performed prior.

Evaluation of bone depth, cortical bone, and mucosa thickness of palatal posterior supra-alveolar insertion site for miniscrew placement

BACKGROUND

The use of palatal miniscrew offers the possibility to improve the effectiveness of orthodontic expansion devices. Palatal expanders supported by miniscrew can be applied with different clinical protocols. Some authors proposed the use of four palatal miniscrews during miniscrew-supported palatal expansion to maximize skeletal effects in young adults' treatment. However, bone availability decreases in the posterior paramedian palatal regions, making the positioning of the two-posterior paramedian palatal miniscrews challenging, when it is performed avoiding nasal cavities invasion. Some authors proposed miniscrews insertion in a specific region located laterally to the palatal process of the maxillary bone, and apically relatively to the dento-alveolar process. The aim of this study was to evaluate the bone thickness, cortical bone thickness, and mucosae depth of this anatomical site that, in this study, was defined as palatal posterior supra-alveolar insertion site.

RESULTS

The evaluation of bone availability of palatal posterior supra-alveolar insertion site at different antero-posterior levels showed that the maximum amount of total bone thickness was found between the second premolar and the first molar. At this level total bone, thickness is significantly (p < .05) greater compared to the other sagittal sites and it offers on average around 2 mm of extra bone depth for miniscrew placement. Cortical bone thickness is adequate for primary miniscrew stability. Overall, cortical bone thickness considered at different insertion sites showed significant statistically (p < .05) differences. The findings of this study showed that palatal mucosa is particularly thick with average values ranging from 4 to 7 mm, and its extension ultimately affects miniscrew length selection. Palatal mucosa thickness showed no clinically significant differences comparing different sagittal and vertical insertion sites. Data also showed that palatal mucosal thickness slightly significantly increases (p < .05) with the inclination of the insertion axis relative to the occlusal plane. Finally, study findings showed that vertical growth pattern can significantly affect considered outcomes (p < .05).

CONCLUSIONS

Palatal posterior supra-alveolar insertion site is an appropriate site for posterior insertion of palatal miniscrews. Considering high anatomical variation preliminary CBCT evaluation is important to achieve optimal miniscrew placement.

Skeletal and alveolar changes in conventional rapid palatal expansion (RPE) and miniscrew-assisted RPE (MARPE): a prospective randomized clinical trial using low-dose CBCT

Background

This prospective randomized clinical trial aimed to evaluate the immediate and short-term skeletal, dentoalveolar, and periodontal effects of rapid palatal expansion (RPE) and miniscrew-assisted RPE (MARPE) in adolescent and young adult patients.

Methods

This study followed a two-arm, parallel, randomized clinical trial design that recruited patients with transverse maxillary deficiency in a 1:1 allocation ratio. Forty patients (14 men and 26 women) requiring maxillary expansion were randomly allocated to the RPE (n = 20, age = 14.0 ± 4.5) or MARPE (n = 20, age = 14.1 ± 4.2) groups. The assignment was performed via computer-generated block randomization, with a block size of four. Upon identical (35 turns) amount of expansion, low-dose cone-beam computed tomography images were taken before treatment (T0), immediately after expansion (T1), and after a 3-month consolidation period (T2). The primary outcome of this study comprised the assessment of midpalatal suture separation. Secondary outcomes included, skeletal, dentoalveolar, and periodontal measurements, which were performed at each time point.

Results

The frequency of midpalatal suture separation was 90% (18/20) and 95% (19/20) for the RPE and MARPE groups, respectively. A greater increase in nasal width in the molar region (M-NW) and greater palatine foramen (GPF) was observed immediately after the expansion (T1-T0) and consolidation periods (T2-T0) in the MARPE group compared to the RPE group (P < 0.05). The MARPE and RPE groups showed similar dentoalveolar changes except for the maxillary width (PM-MW, M-MW). The MARPE group presented greater bilateral first premolar (PM-MW) and molar (M-MW) maxillary width in relation to the RPE group (P < 0.05). Through the expansion and consolidation periods (T2-T0), lesser buccal displacement of the anchor teeth was observed in the MARPE group (PM-BBPT, PM-PBPT, M-BBPT [mesial and distal roots], and M-PBPT)( P < 0.05).

Conclusions

Midpalatal suture separation was observed in 90% and 95% of patients in the RPE and MARPE groups, respectively. Both RPE and MARPE groups exhibited significant triangular basal bone expansion and skeletal relapse during consolidation. Under identical amounts of expansion, the MARPE group showed lower decrease in the skeletal, dentoalveolar and periodontal variables after consolidation. The reinforcement of RPE with miniscrews contributes to the maintenance of the basal bone during consolidation period.

Trial registration WHO Institutional Clinical Trials Registry Platform (IRB No. KCT0006871 / Registration date 27/12/2021).

Mini-implant assisted rapid palatal expansion (MARPE) effects on adult obstructive sleep apnea (OSA) and quality of life: a multi-center prospective controlled trial

Introduction

Transverse maxillary deficiency is a high prevalent growth disorder within the adult population that may lead to serious health issues, such as detrimental malocclusions and higher risk of developing obstructive sleep apnea (OSA). Mini-implant assisted rapid palatal expansion (MARPE), as it expands the mid-face and augment the nasal and oral cavities dimensions, may reduce the airflow resistance and thus play an important role on OSA therapy in some patients. The main objective of the present trial is to assess MARPE effects on the sleep and quality of life of non-obese adult OSA patients with transverse maxillary deficiency.

Methods

A total of 32 participants were divided into intervention and control groups. They underwent physical evaluation, Epworth Sleepiness Scale (EES) and Quebec Sleep Questionnaire (QSQ), cone-beam computed tomography (CBCT) and home sleep testing (HST) for OSA before MARPE (T1) and 6 months after the intervention (T2).

Results

Questionnaires EES (daytime sleepiness) and QSQ (OSA-related quality of life) presented significant statistical differences between the groups. We also found clinical and statistical (p < 0.01) differences between the groups regarding the apnea/hypopnea index (AHI), as well as others HST parameters (mean oxygen saturation and snoring duration).

Conclusion

In our sample, MARPE (without any auxiliary osteotomy) showed a good success rate (85%) and promoted important occlusal and respiratory benefits. We observed important daytime sleepiness and OSA-related quality of life improvement, as well as the AHI (65.3%), oxygen saturation and snoring duration.

Miniscrew-assisted rapid palatal expansion (MARPE): how to achieve greater stability. In vitro study

Objective:

Assess the influence of mono- and bicortical anchorage and diameter of mini-implants (MIs) on the primary stability of these devices.

Methods:

60 self-drilling MIs were distributed in six groups according to diameter (1.5mm, 1.8mm or 2.0mm) and type of anchorage (monocortical and bicortical) in bovine rib. The primary stability was evaluated by insertion torque, micromobility and pull-out strength tests. ANOVA and/or Tukey analysis were used to conduct intergroup comparisons (p< 0.05). Non-parametric statistics (Kruskal-Wallis and Mann-Whitney) were performed when normality was not found (p< 0.05).

Results:

MIs with larger diameters and bicortical anchorage showed greater primary stability regarding insertion torque (p< 0.05) and micromobility (p< 0.05). Only MI diameter had an effect on the pull-out strength test. Larger diameter MIs presented better retention in pull-out strength tests (p< 0.001), regardless of mono- or bicortical anchorage.

Conclusions:

MI primary stability is dependent on its diameter and type of anchorage. Bicortical anchorage showed greater stability when compared with monocortical anchorage, independently of other variables.

Palatal bone thickness at the implantation area of maxillary skeletal expander in adult patients with skeletal Class III malocclusion: a cone-beam computed tomography study

Background

Maxillary skeletal expanders (MSE) is effective for the treatment of maxillary transverse deformity. The purpose of the study was to analyse the palatal bone thickness in the of MSE implantation in patients with skeletal class III malocclusion.

Methods

A total of 80 adult patients (40 males, 40 females) with an average angle before treatment were divided into two groups, the skeletal class III malocclusion group and the skeletal I malocclusion group, based on sagittal facial type. Each group consisted of 40 patients, with a male to female ratio of 1:1. A cone-beam computed tomography scanner was employed to obtain DICOM data for all patients. The palatal bone thickness was measured at 45 sites with MIMICS 21.0 software, and SPSS 22.0 software was employed for statistical analysis. The bone thickness at different regions of the palate in the same group was analysed with one-way repeated measures ANOVA. Fisher’s least significant difference-t method was used for the comparison of pairs, and independent sample t test was employed to determine the significance of differences in the bone thickness at the same sites between the two groups.

Results

Palatal bone thickness was greater in the middle region of the midline area (P < 0.01), while the thickness in the middle and lateral areas in both groups was generally lower (P < 0.001). The bone in the anterior, middle, and posterior regions of the two groups became increasingly thin from the middle area toward the parapalatine region. The palatal bone was significantly thinner in the area 9.0 mm before the transverse palatine suture in the midline area, 9.0 mm before and after the transverse palatine suture in the middle area, and 9.0 mm after the transverse palatine suture in the lateral area.

Conclusion

The palatal bone was thinner in patients with class III malocclusion than in patients with class I malocclusion, with significant differences in some areas. The differences in bone thickness should be considered when MSE miniscrews are implanted. The anterior and middle palatal areas are safer for the implantation of miniscrews, while the thinness of the posterior palatal bone increases the risk of the miniscrews falling off and perforating.

Oropharyngeal 3-dimensional changes after maxillary expansion with 2 different orthodontic approaches

INTRODUCTION

The objective of this research was to compare the oropharyngeal volume and minimal cross-sectional area (MCA) changes after maxillary expansion using either the Damon system or Hyrax appliances as assessed through cone-beam computed tomography (CBCT) imaging.

METHODS

Patients aged between 11 and 17 years with skeletal maxillary transverse discrepancy in need of maxillary expansion were included and allocated randomly into 1 of the 2 treatment groups, Damon or Hyrax. Patients underwent CBCT imaging at 2 time points: T1, after initial clinical evaluation before treatment, and T2, after completion of full orthodontic treatment. The CBCT data were assessed using Dolphin software (Dolphin Imaging & Management Solutions, Chatsworth, Calif). In addition, a qualitative assessment of breathing function was done using the modified Nasal Obstruction and Septoplasty Effectiveness Scale questionnaire.

RESULTS

A statistically significant increase in the oropharyngeal volume (2.23 mL; P = 0.005) and MCA (29.72 mm²; P = 0.007) after the completion of treatment (T2 - T1) for the Hyrax group was suggested. No statistically significant difference was found in the Damon group for volume (1 mL; P = 0.311) and for MCA (7.32 mm²; P = 0.643). In addition, no statistically significant difference was found in the breathing function in both treatment groups (P >0.05).

CONCLUSIONS

Hyrax expansion followed by fixed appliances produced more dimensional upper airway changes at the oropharyngeal level than the Damon system approach. No breathing functional changes were noted in either samples.

Maxillary dental and skeletal effects after treatment with self-ligating appliance and miniscrew-assisted rapid maxillary expansion

INTRODUCTION

The objective of the present study was to compare the maxillary dental and skeletal effects after treatment with self-ligating appliance and miniscrew-assisted rapid maxillary expansion (MARPE).

METHODS

The sample comprised 37 patients with Class I malocclusion treated without tooth extraction, divided into 2 groups: group 1 comprises 21 patients with a mean age of 19.55 years (standard deviation = 1.31), submitted to orthodontic treatment with Damon self-ligating appliance, and evaluated until the end of the alignment and leveling stage. Group 2 comprises 16 patients with a mean age of 24.92 years (standard deviation = 7.60), with maxillary atresia, who underwent MARPE, and were evaluated after the removal of the expander. Buccal bone thickness; dental inclinations; and transverse distances of the maxillary arch, nasal base, and jugula widths were measured on cone-beam computed tomography scans before and after treatment. The intergroup comparison was performed with the independent t test.

RESULTS

With treatment, there was a significantly greater decrease in buccal bone thickness of canines and premolars in the self-ligating group, the premolars presented a greater buccal inclination in the self-ligating group, and the intercanine and intermolar distances and nasal base and jugula widths showed significantly greater increases in the MARPE group than in the self-ligating group.

CONCLUSIONS

MARPE treated more severe skeletal transverse maxillary discrepancies and obtained better results than self-ligating appliances in terms of buccal bone loss, tooth inclination, and transverse skeletal increase of the maxilla. MARPE presented more skeletal effects and self-ligating appliances, more dental effects.

Assessment of stiffness and load deflection of orthodontic miniscrews used for palatal anchorage: An in vitro biomechanical study

OBJECTIVE

The purpose of this study was to evaluate the biomechanical properties of miniscrews of 5 different lengths, 2 different diameters, and different combinations of insertion used for palatal skeletal anchorage.

MATERIALS AND METHODS

Twenty-four different combinations of a total of 120 miniscrews of two different diameters (2.0mm and 2.3mm) and five different lengths (9mm, 11mm, 13mm and 15mm) were tested at different angles of insertion (90° and 45°) and distances from a synthetic bone block (3mm, 5mm, 7mm). Samples were fixed in an Instron Universal Testing Machine and a load was applied in single cantilever mode to the neck of each miniscrew. The stiffness and maximum load before permanent deformation were recorded. Model-based recursive partitioning testing (CART) was used to evaluate differences between groups.

RESULTS

Significantly higher forces were necessary to deform miniscrews of diameter 2.3mm than those of 2.0mm, those inserted at an angle of 45° with respect to 90°, and at smaller distances between the miniscrew neck and block; in addition, the maximum load and stiffness increased with increasing screw length.

CONCLUSION

This in vitro experimental study showed strong correlations between deformation load and miniscrew geometry, insertion angle and distance from the synthetic block, results that should be considered when planning miniscrew insertion in order to reduce the risk of unwanted fracture.

Complex clinical case with Class III and open bite: stability after seven years

A healthy 15-year-old boy with anterior open bite, edge-to-edge transverse discrepancy, and Class III skeletal relationship sought a nonsurgical orthodontic treatment. The patient was treated with premolars extraction, a Hyrax expander and intrusion mechanics with vertical elastics. This mechanics allowed for excellent facial and occlusal results. The final occlusion presented Class I molar and canine relationships, ideal overjet and overbite, and straight facial profile. Analysis of the posttreatment and follow-up radiographs showed that the treatment outcomes remained stable seven years after active orthodontic treatment. Thus, although combined orthodontic and surgical treatment should be considered for patients with this skeletal malocclusion, this case report proves that well controlled orthodontic movement with the patient's cooperation can be a valid alternative treatment, with good and stable outcomes for patients who refuse surgery.

Transverse maxillary deficiency: treatment alternatives in face of early skeletal maturation

Transverse deficiencies should be a priority in orthodontic treatment, and should be corrected as soon as diagnosed, to restore the correct transverse relationship between maxilla and mandible and, consequently, normal maxillary growth. Corrections may be performed at the skeletal level, by opening the midpalatal suture, or by dentoalveolar expansion. The choice of a treatment alternative depends on certain factors, such as age, sex, degree of maxillary hypoplasia and maturation of the midpalatal suture. Thus, the present study discusses different treatment approaches to correct maxillary hypoplasia in patients with advanced skeletal maturation.

Predictors of midpalatal suture expansion by miniscrew-assisted rapid palatal expansion in young adults: A preliminary study

OBJECTIVE

We sought to determine the predictors of midpalatal suture expansion by miniscrew-assisted rapid palatal expansion (MARPE) in young adults.

METHODS

The following variables were selected as possible predictors: chronological age, palate length and depth, midpalatal suture maturation (MPSM) stage, midpalatal suture density (MPSD) ratio, the sella-nasion (SN)-mandibular plane (MP) angle as an indicator of the vertical skeletal pattern, and the point A-nasion-point B (ANB) angle for anteroposterior skeletal classification. For 31 patients (mean age, 22.52 years) who underwent MARPE treatment, palate length and depth, MPSM stage and MPSD ratio from the initial cone-beam computed tomography images, and the SN-MP angle and ANB angle from lateral cephalograms were assessed. The midpalatal suture opening ratio was calculated from the midpalatal suture opening width measured in periapical radiographs and the MARPE screw expansion. Statistical analyses of correlations were performed for the entire patient group of 31 subjects and subgroups categorized by sex, vertical skeletal pattern, and anteroposterior skeletal classification.

RESULTS

In the entire patient group, the midpalatal suture opening ratio showed statistically significant negative correlations with age, palate length, and MPSM stage (r = -0.506, -0.494, and -0.746, respectively, all p < 0.01). In subgroup analyses, a strong negative correlation was observed with the palate depth in the skeletal Class II subgroup (r = -0.900, p < 0.05).

CONCLUSIONS

The findings of this study indicated that age, palate length, and MPSM stage can be predictors of midpalatal suture expansion by MARPE in young adults.

Midpalatal suture maturation stage assessment in adolescents and young adults using cone-beam computed tomography

Background

The aim of this study was to evaluate the midpalatal suture maturation stages in adolescents and young adults using cone-beam computed tomography (CBCT).

Methods

The sample comprised 200 CBCT scans of individuals aged 10 to 25 years old (95 males and 105 females) divided into three groups, adolescents (n = 48), post-adolescents (n = 52), and young adults (n = 100). The Planmeca ProMax 3D software was used for the midpalatal suture maturation stage evaluation according to Angieleri’s method, using cross-sectional axial slice. Two previously calibrated examiners analyzed the images and classified according to five different maturation stages. A, B, and C stages were considered with open midpalatal suture, and D and E were considered without open midpalatal suture. Association tests were performed using chi-square test also, and a binary logistic regression was evaluated (P < 0.05).

Results

The possibility to find open midpalatal suture in individuals of 10 to 15 years old was 70.8%, in subject aged 16 to 20 and 21 to 25 years old was 21.2% and 17%, respectively. Furthermore, this possibility in individuals older than 16 years was greater in males than in females.

Conclusions

The possibility to find open midpalatal suture in post-adolescents and young adults is greater than the orthodontists considered years ago. Furthermore, men are more likely to find midpalatal suture opening. These implications might be considered by the orthodontists when maxillary expansion is required. Besides, the ossification of the middle palatal suture is very variable, and therefore, the use of CBCT might be recommended to clarify this possibility.

Mini-implant selection protocol applied to MARPE

Introduction:

Rapid maxillary expansion (RME) is the therapy of choice to correct skeletal transverse dimension in children and adolescents, associating orthopedic and dental effects. In an attempt to prevent the undesirable dentoalveolar effects and optimize the potential of skeletal expansion in individuals in advanced stages of skeletal maturation, the miniscrew-assisted rapid palatal expander (MARPE) was proposed by Lee et al. in 2010.

Objective:

This paper presents a systematized protocol for selection of miniscrews indicated for MARPE, by the evaluation of cone-beam computed tomographies (CBCT). Variables related with the bone and soft tissue thicknesses at the palatal regions of interest, as well as in relation to the fixation rings of miniscrews of the palatal expander are analyzed and discussed to provide better performance in the clinical practice.

Quantitative Evaluation of Midpalatal Suture Opening and Its Relation with Zygomaticomaxillary Suture Status in Patients Aged 7-25 Years Using Cone Beam Computed Tomography Images: In an Iranian Population

Objective

The purposes of this study were to determine the midpalatal suture (MPS) opening depth and to assess its relation with the zygomaticomaxillary suture (ZMS) by age with using cone beam computed tomography (CBCT).

Materials and Methods

In this cross-sectional study, 167 CBCT scans of patients aged 7-25 years (mean age: 16.04 ± 5.17 years) were selected based on predefined criteria and categorized into four age groups. The mean percentages of the depth of MPS opening at anterior, middle, and posterior regions in the coronal and closure status of ZMS in axial views were determined by a maxillofacial radiologist.

Results

The mean percentages of MPS opening depth at anterior, middle, and posterior regions were 98.20%, 89.27%, and 71.44%, respectively. In these regions, 20-25-year age group showed a significant difference compared with first- and second-age groups. A significant difference was observed in the frequencies of complete MPS opening in different age groups in the middle (P = 0.017) and posterior (P = 0.001) regions. About 80.20% patients had open ZMS bilaterally. The percentages of opening depth in the three regions were 97.8%, 91.8%, and 75.6%, respectively, when ZMS was open on both sides.

Conclusion

Percentage of opening depth of this suture decreased by age. MPS closure starts from the posterior region. ZMS in younger people is usually open on both sides; however, it can be closed on one or both sides by age. An association was observed between bilateral closure or opening of ZMS and mean percentage of MPS opening in the middle and posterior regions.