A preliminary study of buccal and lingual alveolar bone thickness of posterior teeth in patients with skeletal Class III malocclusion and mandibular asymmetry.

INTRODUCTION: The purposes of this retrospective study were to investigate the buccal and lingual alveolar bone thickness values of the posterior teeth in patients with asymmetrical skeletal Class III malocclusion and compare them with patients with symmetrical skeletal Class III and Class I malocclusion. METHODS: Seventy-eight cone-beam computed tomography scans were classified into 3 groups according to the sagittal pattern and menton deviation: asymmetrical Class III (n = 26), symmetrical Class III (n = 26), and symmetrical Class I (n = 26). The buccal and lingual alveolar bone thickness of the first molar and premolars in the maxilla and mandible were measured at 3, 6, and 8 mm apical to the cementoenamel junction and the apical and middle levels of the root. Measurements were compared among the 3 groups. RESULTS: In the asymmetrical Class III group, the buccal alveolar bone along the distobuccal root of the maxillary first molar on the deviated side was thinner by 1.07 to 1.10 mm than that in the symmetrical Class I group at 6-mm, 8-mm, and middle-level planes (P <0.001, P <0.01, and P <0.001). The buccal alveolar bone thickness along the distal and mesial roots of the mandibular first molar on the deviated side was thinner by 1.28 to 1.85 mm, and by 0.72 to 1.21 mm, respectively (P <0.001 and P <0.01), than that in the symmetrical Class I group at 6-mm, 8-mm, apical and middle-level planes. CONCLUSIONS: In this preliminary study, patients with skeletal Class III malocclusion showed thinner buccal and lingual alveolar bone in the posterior teeth than subjects with Class I malocclusion. Particular attention should be paid to buccal alveolar bone thickness along the distobuccal root of the maxillary and distal root of the mandibular first molar to prevent periodontal complications in decompensation. Future studies should involve larger sample sizes, more repeatable and comprehensive measuring and statistical methods.

Comparison of mandibular cross-sectional morphology between Class I and Class II subjects with different vertical patterns: based on CBCT images and statistical shape analysis.

BACKGROUND: This study is aimed to (1) investigate the influence of sagittal and vertical patterns on mandibular cross-sectional morphology and to (2) provide visualized mandibular cross-sectional morphology in different groups with General Procrustes Analysis (GPA), canonical variance analysis (CVA) and discriminant function analysis (DFA). METHODS: 324 cone-beam computed tomography (CBCT) images were collected to analyze mandibular cross-sectional morphology and were categorized into 12 groups according to sagittal and vertical pattern and gender. One-way analysis of variance (ANOVA) was used to compare the difference among the groups. Thirty equidistant points were marked along the contour of mandibular cross-section and GPA, CVA and DFA were applied. RESULTS: (1) Mandibular height in hyperdivergent groups was significantly higher than that in normodivergent and hypodivergent groups (P < 0.05). (2) Hypodivergent groups showed significantly wider upper third of mandibular width from symphysis to molar region than that in hyperdivergent group (P < 0.05), except for the premolar and molar regions in male groups (P > 0.05). (3) Class II hyperdivergent group showed narrowest lower third width in the molar region, with the mean value of 12.03 mm in females and 11.98 mm in males. (4) For males and females, the ratio between height and lower third width at symphysis was significantly higher in Class II hyperdivergent group than that in Class I hyperdivergent group (P < 0.05). CONCLUSIONS: (1) The influence of vertical facial patterns on mandibular cross-sectional morphology is more obvious than that of sagittal skeletal pattern. (2) Subjects with increased vertical dimension presented with a remarkable "slimer" mandibular cross-sectional morphology at symphysis. (3) A deeper curve along the anterior contour of symphysis in Class II hyperdivergent group was noted with GPA.

Assessment of buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth in patients with severe skeletal Class III malocclusion with mandibular asymmetry.

INTRODUCTION: The purpose of this study was to evaluate the buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth in patients with severe skeletal Class III malocclusion with and without mandibular asymmetry and compare with those in patients with skeletal Class I malocclusion. METHODS: Cone-beam computed tomography images of 69 patients with severe skeletal Class III malocclusion and 30 patients with skeletal Class I malocclusion were collected and reconstructed with Dolphin 3D software. Based on the distance from menton to the sagittal plane (d), the patients with skeletal Class III malocclusion were divided into a symmetry group (d ≤ 2 mm) and an asymmetry group (d ≥ 4 mm). Buccal and lingual alveolar bone thickness and buccolingual inclination of maxillary posterior teeth were measured and compared. Correlations among dental measurements, severity of sagittal discrepancy, and mandibular deviation were analyzed. RESULTS: Maxillary posterior teeth on the deviated side in Class III asymmetry group and symmetry group were buccally inclined compared with the Class I group (P < 0.001). A significant negative correlation was noted between buccolingual inclination of maxillary posterior teeth and ANB value with Spearman correlation coefficient of maxillary first molar, second premolar, and first premolar of -0.687, -0.485 and -0.506, respectively (P < 0.001). Maxillary first molar showed thinner buccal alveolar bone on deviated side in asymmetry group and symmetry group of Class III, compared with the Class I group, with average values of 1.21 mm, 1.19 mm, and 1.83 mm, respectively (P < 0.05). The maxillary first premolar also showed thinner buccal alveolar bone on deviated side in Class III asymmetry group compared with the Class I group, with average values of 0.87 mm and 1.28 mm, respectively (P < 0.05). CONCLUSIONS: Decompensation of buccally inclined posterior teeth in patients with skeletal Class III malocclusion should be more cautious owing to thinner buccal alveolar bone to avoid a high risk of fenestration and dehiscence.

Preliminary comparison of three-dimensional reconstructed palatal morphology in subjects with different sagittal and vertical patterns.

BACKGROUND: The aim of this study was to assess the difference of palatal morphology in different vertical patterns between skeletal Class I subjects and skeletal Class II subjects with retrusive mandible. METHODS: Seventy-six skeletal Class II subjects with retrusive mandible (38 females, 38 males) and 85 skeletal Class I subjects (45 females, 40 males) were collected retrospectively and divided into hyperdivergent, normodivergent and hypodivergent groups. CBCT images of these subjects were reoriented by Dolphin 3D Imaging software. Three-dimensional (3D) maxilla was segmented by ProPlan software before using Geomagic Studio software to reconstruct 3D palatal morphology. Deviation patterns on 3D colored map analysis was performed to compare the difference of 3D palatal morphology between different groups. RESULTS: 3D colored map analysis showed that male's palate was higher and wider than that of female in the posterior part, regardless of different sagittal and vertical patterns. In skeletal Class II subjects with retrusive mandible, males with hyperdivergent and normodivergent showed higher and narrower in the posterior part of palate, while females with hyperdivergent and normodivergent had a higher but no obviously narrow palate compared with the hypodivergent subjects. Skeletal Class II subjects with retrusive mandible showed flatter and narrower in the posterior part of palate than that of skeletal Class I subjects. CONCLUSIONS: Sagittal and vertical patterns have great influence on the palatal morphology and as the vertical dimension increased, the palate tended to be higher and narrower.

Analysis of salivary exosomal proteins in young adults with severe periodontitis.

OBJECTIVES: Salivary exosomes harbour numerous constituents associated with oral and systemic diseases. However, no reports addressed components of salivary exosomes in patients with periodontitis. Our study aims to explore salivary exosomal proteins in young adults with severe periodontitis (SP) and to analyse the relationships between different proteins. MATERIALS AND METHODS: We collected saliva from 11 young adults with SP and 11 periodontally healthy subjects. After isolation of salivary exosomes, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyse proteins. Gene ontology analysis was performed based on GeneCodis, and interaction network analysis for unique salivary exosomal proteins was performed by STRING. RESULTS: Twenty-six proteins were identified only in the SP group, and 58 proteins were identified only in the healthy group. Gene ontology analysis revealed that innate immune response, cytolysis and complement activation were highly enriched in the SP group. Interaction network analysis showed that the correlations among immune-related proteins (e.g. complement components and chemokine (C-C motif) ligand 28) were significant in the SP group. C6 proteins expressed only in the SP group were evaluated by Western blotting. CONCLUSIONS: Salivary exosomes from periodontitis patients are enriched immune-related proteins that might participate in the immune response during the development of periodontitis.