The objective of this research was to compare maxillary width and hard palate thickness in men and women with different vertical and sagittal skeletal patterns.
A total of 241 adults (93 men and 148 women aged from 18 to 25 years) were divided into male and female groups. Subjects were then separately divided into 3 sagittal skeletal groups and 3 vertical skeletal groups. A lateral cephalogram and a cone-beam computed tomography were taken for each subject. We measured the parameters to make statistical analyses and compared them between the different groups.
Women had smaller craniomaxillofacial bone width and palatal thickness than men. In sagittal groups, maxillary width, maxillary alveolar width, and external temporomandibular joint fossa width in Class II and Class III malocclusion groups were smaller than in the Class I group for both women and men. The internal temporomandibular joint fossa width was the same results in men and women. In vertical groups, palate thickness, maxillary width, and maxillary alveolar width of the high-angle group were smaller than those of the low-angle group, regardless of sex.
To an extent, maxillary width is correlated with vertical and sagittal skeletal patterns, and insufficient maxillary width would lead to unfavorable skeletal patterns. Differences exist in the morphology of craniomaxillofacial bone between men and women. Therefore, these findings can provide clinicians with references for differential diagnosis and treatment plans.
Different skeletal patterns are associated with maxillary width and palate thickness in Chinese .
The above differences were similar in men and women.
Men had more counterclockwise rotation tendency, whereas women had more clockwise rotation.
Malocclusions in 3 dimensions (3D) often occur at the same time and usually interrelate with each other. Growth follows the sequential completion of the cranium followed by width (transverse), then depth (sagittal), and finally, height (vertical). Transverse growth was found to achieve near completion by late adolescence. However, sagittal and vertical growth continues well into adulthood. Therefore, lack of maxillary transverse width will affect vertical and sagittal development of maxillofacial bone in the early stages, which is hard to perceive. Malocclusion usually occurs in mixed dentition or permanent dentition when the transverse development approaches completion. For this situation, patients usually did not report the insufficient transverse width but the sagittal problem as their main complaint, so clinicians were often more likely to pay attention to the sagittal dimension. However, more recently, the contributions of maxillary expansion have become well known by many dental professionals. When making a decision between nonextraction with maxillary expansion and extraction treatment modalities in borderline patients, clinicians should make differential diagnoses cautiously and choose a treatment plan suiting the maxillary width of the patient.
The attention to transverse width will be helpful in malocclusion diagnosis, differential diagnosis, and the formulation of treatment plans. In addition, maxillomandibular coordinate width is crucial for a stable transverse intercuspal relationship, stable mandible position, comfortable condylar position, functional coordination of maxillofacial nerve and muscle system, and a stable long-term curative effect. In clinical practice, maxillary skeletal expansions are usually used for insufficient maxillary transverse width. Therefore, to guide screw implantation and surgical design of expansion, we measured the posterior portion of the hard palate, where it was often the position of screw implantation in maxillary skeletal expansions clinically.
In previous studies, scholars paid more attention to the issues of sagittal direction and vertical orientation. However, concerns about the transverse problem were relatively insufficient. Because of race, sample sizes, reference points, measurement parameters, and other inconsistencies, the results of transverse width studies by different scholars were diverse.
The purpose of this study was to investigate the differences in transverse width and hard palate thickness in men and women with different sagittal and vertical patterns, which will provide references for our clinicians for diagnosis and treatment plan options for various sagittal skeletal patterns, and vertical skeletal patterns as well. This study looked at Chinese Northerners, and the results might not apply to people of other regions.
Material and methods
The research was done at the Stomatological Hospital of Shandong University, from which information on consecutive records of 93 men and 148 women were obtained. Patients aged 18 to 25 years with permanent dentition were selected as experimental objects, excluding the effects of growth and development. All subjects were Chinese Northerners with the following exclusions: (1) craniofacial anomalies, syndromes, severe asymmetries, and clefts; (2) crossbites and history of orthodontic treatment; (3) degenerative diseases of temporomandibular joint (TMJs); and (4) other systemic diseases and clinical history.
For each subject, data including lateral cephalogram and cone-beam computed tomography (CBCT) (acquired by New Tom 5G CBCT scanner, QR system, Verona, Italy, with exposure settings of 110 kV, 12-in field of view, and 5.4-second exposure time) with the teeth in centric occlusion (obtained at the same time) were collected to make an exact diagnosis and acquire information regarding the 3D configuration of maxillofacial bone. Every original image file of CBCT was reconstructed in 3D with Dolphin Imaging software (version 11.8; Dolphin Imaging and Management Solutions, Chatsworth, Calif). The grouping principle and sample distribution are shown in Tables II-VIII ). Informed consent statements were acquired from all subjects. Subjects were on premises to ensure against systematic diseases and contraindications, and they were kept under strict protection when CBCTs were taken. This study was approved by the Medical Ethics Committee of the Stomatological Hospital of Shandong University.
|Bizygomatic width (ZZ) ( Fig 2 )||ZZ, transverse width between the lateral pterygoid plates; Za, zygomatic arch landmarks|
|Maxillary alveolar widths (BAC and LAC) ( Fig 2 )||BAC, maxillary width at the level of the buccal alveolar crest; LAC, maxillary width between the lingual alveolar crests|
|Maxillary widths (NF and HP) ( Fig 2 )||NF, maxillary width parallel to the lower border of the CBCT image and tangent to the nasal floor at its most superior level; HP, maxillary width parallel to the lower border of the CBCT image and tangent to the hard palate|
|TMJ fossa widths , ( Fig 3 )||External and internal TMJ fossa width (determined in the plane where condyle had the largest length in coronal views)
LSF, latero-superior TMJ fossa landmarks; LIF, latero-inferior TMJ fossa landmarks; CC, center of the condyles
|Hard palatal thickness ( Fig 5 )||Hard palatal thickness at second premolar and first molar levels; 5 palatal thickness, midpoint of bilateral second premolar and palate middle seam; 6 palatal thickness, midpoint of bilateral first molar and palate middle seam|
|Pterygoid width (PW) ( Fig 4 )||Transverse width between the lateral pterygoid plates|
|APDI (°)||APDI = ∠FH-NPog ± ∠AB-NPog ± ∠PP-FH|
|ANB (°)||ANB = ∠A-N-S − ∠B-N-S|
|Sum (°)||Sum = ∠N-S-Ar + ∠S-Ar-Go + ∠Ar-Go-Me|
|Anterior cranial base length (SN) (mm)||Line distance between sella point and nasion point|
|Posterior cranial base length (SAr) (mm)||Line distance between sella point and articulare point|
|Sella angle (°)||∠N-S-Ar|
|Articulare angle (°)||∠S-Ar-Go|
|CBCT measurements||Class I group (n = 66)||Class II group (n = 41)||Class III group (n = 41)||F||P|
|External TMJ fossa width||117.64||113.18||112.50||3.572||0.031|
|Internal TMJ fossa width||80.86||80.40||78.85||2.678||0.082|
|5 Palatal thickness||4.21||4.12||4.78||1.144||0.322|
|6 Palatal thickness||2.11||2.31||2.53||1.519||0.222|
|CBCT measurements||Class I group (n = 31)||Class II group (n = 27)||Class III group (n = 35)||F||P|
|External TMJ fossa width||126.26||124.36||123.81||3.276||0.031|
|Internal TMJ fossa width||86.22||83.92||83.30||9.580||0.001|
|5 Palatal thickness||5.87||5.06||5.38||0.615||0.543|
|6 Palatal thickness||2.51||2.93||2.29||2.061||0.133|
|Class I vs Class II||Class I vs Class III||Class II vs Class III||Class I vs Class II||Class I vs Class III||Class II vs Class III|
|External TMJ fossa width||0.025||0.041||0.692||0.033||0.032||0.531|
|Internal TMJ fossa width||0.009||0.007||0.771||–||–||–|
|CBCT measurements||Low-angle group (n = 40)||Average-angle group (n = 63)||High-angle group (n = 45)||F||P|
|External TMJ fossa width||116.01||115.33||114.4||0.311||0.734|
|Internal TMJ fossa width||81.16||80.98||79.52||0.452||0.638|
|5 Palatal thickness||4.85||4.41||4.02||3.571||0.021|
|6 Palatal thickness||2.28||2.44||2.76||2.808||0.066|