Yong Il Kim

Cone-beam computed tomography evaluation of short- and long-term airway change and stability after orthognathic surgery in patients with Class III skeletal deformities: bimaxillary surgery and mandibular setback surgery

The purpose of this study was to evaluate the volumetric change of the upper airway space in 36 Class III patients who had undergone bimaxillary surgery or isolated mandibular setback, and, further, to analyse the relation between post-surgical stability and airway change using cone-beam computed tomography (CBCT). A three-dimensional (3D) CBCT examination was performed at three stages: T0 (before surgery), T1 (an average of 4.6 months after surgery), and T2 (an average of 1.4 years after surgery). The results showed that the volumes of the oropharyngeal and hypopharyngeal airways decreased significantly 4.6 months post-surgery in the mandibular setback group (p<0.05), and these diminished airways had not recovered 1.4 years post-surgery. In the bimaxillary surgery group, the volume of the oropharyngeal airway also decreased. A Spearman correlation analysis showed that the anteroposterior length of the hypopharyngeal area had a correlation with post-surgical stability in the isolated mandibular surgery group, and that the cross-sectional area of the nasopharynx was correlated with maxillary relapse only in the bimaxillary surgery group (p<0.05).

Genome-wide association study of degenerative bony changes of the temporomandibular joint

OBJECTIVESnTo identify susceptibility genes underlying degenerative bony changes of the temporomandibular joint (TMJ).nnnMATERIALS AND METHODSnBony changes of the TMJ condylar head were diagnosed by examination of panoramic radiographs and/or magnetic resonance images and/or computed tomography images. We conducted a genome-wide association study (GWAS) of 146 cases with TMJ degeneration and 374 controls from East Asian populations using an Illumina HumanOmniExpress BeadChip. After rigorous quality-control filtering, approximately 550,000 single nucleotide polymorphisms (SNPs) were used for tests of associations with disease status.nnnRESULTSnForty-one SNPs at 22 independent loci showed association signals at P < 1 × 10(-4). The SNP rs878962, which maps on an intron of TSPAN9 on chromosome 12, showed the strongest association (combined OR = 1.89, 95% confidence interval = 1.43-2.50, P = 8.1 × 10(-6)). According to in silico predictions of the 41 SNPs, two intronic SNPs of APOL3 (rs80575) and MRC2 (rs2460300) may fall within regulatory elements and affect DNA-protein interactions. We could not replicate SNPs located on genes that have been reported to be associated with temporomandibular disorder or temporomandibular osteoarthritis in previous studies at P < 1 × 10(-4).nnnCONCLUSIONSnOur GWAS identified 22 independent loci showing suggestive association signals with degenerative bony changes of the TMJ. These loci provide good candidates for future follow-up studies.

Quantitative evaluation of midpalatal suture maturation via fractal analysis

Objective The purpose of this study was to determine whether the results of fractal analysis can be used as criteria for midpalatal suture maturation evaluation. Methods The study included 131 subjects aged over 18 years of age (range 18.1–53.4 years) who underwent cone-beam computed tomography. Skeletonized images of the midpalatal suture were obtained via image processing software and used to calculate fractal dimensions. Correlations between maturation stage and fractal dimensions were calculated using Spearmans correlation coefficient. Optimal fractal dimension cut-off values were determined using a receiver operating characteristic curve. Results The distribution of maturation stages of the midpalatal suture according to the cervical vertebrae maturation index was highly variable, and there was a strong negative correlation between maturation stage and fractal dimension (−0.623, p < 0.001). Fractal dimension was a statistically significant indicator of dichotomous results with regard to maturation stage (area under curve = 0.794, p < 0.001). A test in which fractal dimension was used to predict the resulting variable that splits maturation stages into ABC and D or E yielded an optimal fractal dimension cut-off value of 1.0235. Conclusions There was a strong negative correlation between fractal dimension and midpalatal suture maturation. Fractal analysis is an objective quantitative method, and therefore we suggest that it may be useful for the evaluation of midpalatal suture maturation.

Correlation between skeletal and dental changes after mandibular setback surgery-first orthodontic treatment: Cone-beam computed tomography-generated half-cephalograms

Objective To investigate skeletal and dental changes after application of a mandibular setback surgery-first orthodontic treatment approach in cases of skeletal Class III malocclusion. Methods A retrospective study of 34 patients (23 men, 11 women; mean age, 26.2 ± 6.6 years) with skeletal Class III deformities, who underwent surgery-first orthodontic treatment, was conducted. Skeletal landmarks in the maxilla and mandible at three time points, pre-treatment (T0), immediate-postoperative (T1), and post-treatment (T2), were analyzed using cone-beam computed tomography (CBCT)-generated half-cephalograms. Results The significant T0 to T1 mandibular changes occurred -9.24 ± 3.97 mm horizontally. From T1 to T2, the mandible tended to move forward 1.22 ± 2.02 mm, while the condylar position (Cd to Po-perpendicular plane) shifted backward, and the coronoid process (Cp to FH plane) moved vertically. Between T1 and T2, the vertical dimension changed significantly (p < 0.05). Changes in the vertical dimension were significantly correlated to T1 to T2 changes in the Cd to Po-perpendicular plane (r = -0.671, p = 0.034), and in the Cp to FH plane (r = 0.733, p = 0.016), as well as to T0 to T1 changes in the Cp to Po-perpendicular plane (r = 0.758, p = 0.011). Conclusions Greater alterations in the vertical dimension caused larger post-treatment (T2) stage skeletal changes. Studying the mandibular position in relation to the post-surgical vertical dimension emphasized the integral importance of vertical dimension control and proximal segment management to the success of surgery-first orthodontic treatment.

Quantitative skeletal maturation estimation using cone-beam computed tomography-generated cervical vertebral images: a pilot study in 5- to 18-year-old Japanese children

ObjectivesThe purpose of this study was to establish multivariable regression models for the estimation of skeletal maturation status in Japanese boys and girls using the cone-beam computed tomography (CBCT)-based cervical vertebral maturation (CVM) assessment method and hand-wrist radiography.Materials and methodsThe analyzed sample consisted of hand-wrist radiographs and CBCT images from 47 boys and 57 girls. To quantitatively evaluate the correlation between the skeletal maturation status and measurement ratios, a CBCT-based CVM assessment method was applied to the second, third, and fourth cervical vertebrae. Pearsons correlation coefficient analysis and multivariable regression analysis were used to determine the ratios for each of the cervical vertebrae (pu2009<u20090.05).ResultsFour characteristic parameters ((OH2u2009+u2009PH2)/W2, (OH2u2009+u2009AH2)/W2, D2, AH3/W3), as independent variables, were used to build the multivariable regression models: for the Japanese boys, the skeletal maturation status according to the CBCT-based quantitative cervical vertebral maturation (QCVM) assessment was 5.90u2009+u200999.11u2009×u2009AH3/W3u2009−u200914.88u2009×u2009(OH2u2009+u2009AH2)/W2u2009+u200913.24u2009×u2009D2; for the Japanese girls, it was 41.39u2009+u200959.52u2009×u2009AH3/W3u2009−u200915.88u2009×u2009(OH2u2009+u2009PH2)/W2u2009+u200910.93u2009×u2009D2.ConclusionsThe CBCT-generated CVM images proved very useful to the definition of the cervical vertebral body and the odontoid process. The newly developed CBCT-based QCVM assessment method showed a high correlation between the derived ratios from the second cervical vertebral body and odontoid process.Clinical relevanceThere are high correlations between the skeletal maturation status and the ratios of the second cervical vertebra based on the remnant of dentocentral synchondrosis.

Dentin sealing and antibacterial effects of silver-doped bioactive glass/mesoporous silica nanocomposite: an in vitro study

ObjectivesTo synthesize a silver-doped bioactive glass/mesoporous silica nanoparticle (Ag-BGN@MSN), as well as to investigate its effects on dentinal tubule occlusion, microtensile bond strength (MTBS), and antibacterial activity.Materials and methodsAg-BGN@MSN was synthesized using a modified “quick alkali-mediated sol-gel” method. Demineralized tooth disc models were made and divided into four groups; the following treatments were then applied: group 1—no treatment, group 2—bioglass, group 3—MSN, group 4—Ag-BGN@MSN. Next, four discs were selected from each group and soaked into 6xa0wt% citric acid to test acid-resistant stability. Dentinal tubule occlusion, as well as the occlusion ratio, was observed using field-emission scanning electron microscopy. The MTBS was also measured to evaluate the desensitizing effect of the treatments. Cytotoxicity was examined using the MTT assay. Antibacterial activity was detected against Lactobacillus casei, and ion dissolution was evaluated using inductively coupled plasma optical emission spectrometry.ResultsAg-BGN@MSN effectively occluded the dentinal tubule and formed a membrane-like layer. After the acid challenge, Ag-BGN@MSN had the highest rate of dentinal tubule occlusion. There were no significant differences in MTBS among the four groups (Pu2009>u20090.05). All concentrations of Ag-BGN@MSN used had a relative cell viability above 72%.ConclusionsAg-BGN@MSN was successfully fabricated using a modified sol-gel method. The Ag-BGN@MSN biocomposite effectively occluded dentinal with acid-resistant stability, did not decrease bond strength in self-etch adhesive system, had low cytotoxicity, and antibacterial effect.Clininal relevanceDentinal tubule sealing induced by Ag-BGN@MSN biocomposite with antibacterial effect is likely to increase long-term stability in DH.

Cervical Vertebral Body’s Volume as a New Parameter for Predicting the Skeletal Maturation Stages

This study aimed to determine the correlation between the volumetric parameters derived from the images of the second, third, and fourth cervical vertebrae by using cone beam computed tomography with skeletal maturation stages and to propose a new formula for predicting skeletal maturation by using regression analysis. We obtained the estimation of skeletal maturation levels from hand-wrist radiographs and volume parameters derived from the second, third, and fourth cervical vertebrae bodies from 102 Japanese patients (54 women and 48 men, 5–18 years of age). We performed Pearsons correlation coefficient analysis and simple regression analysis. All volume parameters derived from the second, third, and fourth cervical vertebrae exhibited statistically significant correlations (P < 0.05). The simple regression model with the greatest R-square indicated the fourth-cervical-vertebra volume as an independent variable with a variance inflation factor less than ten. The explanation power was 81.76%. Volumetric parameters of cervical vertebrae using cone beam computed tomography are useful in regression models. The derived regression model has the potential for clinical application as it enables a simple and quantitative analysis to evaluate skeletal maturation level.

The skeletal maturation status estimated by statistical shape analysis: axial images of Japanese cervical vertebra.

OBJECTIVESnTo evaluate axial cervical vertebral (ACV) shape quantitatively and to build a prediction model for skeletal maturation level using statistical shape analysis for Japanese individuals.nnnMETHODSnThe sample included 24 female and 19 male patients with hand-wrist radiographs and CBCT images. Through generalized Procrustes analysis and principal components (PCs) analysis, the meaningful PCs were extracted from each ACV shape and analysed for the estimation regression model.nnnRESULTSnEach ACV shape had meaningful PCs, except for the second axial cervical vertebra. Based on these models, the smallest prediction intervals (PIs) were from the combination of the shape space PCs, age and gender. Overall, the PIs of the male group were smaller than those of the female group. There was no significant correlation between centroid size as a size factor and skeletal maturation level.nnnCONCLUSIONSnOur findings suggest that the ACV maturation method, which was applied by statistical shape analysis, could confirm information about skeletal maturation in Japanese individuals as an available quantifier of skeletal maturation and could be as useful a quantitative method as the skeletal maturation index.

Comparison of postoperative changes in the distal and proximal segments between conventional and sliding mini-plate fixation following mandibular setback

Objective The purpose of the present study was to evaluate the postoperative three-dimensional (3D) changes in the proximal segments after mandibular setback sagittal split ramus osteotomy and to compare the changes between the conventional mini-plate fixation and semi-rigid sliding plate fixation. Methods Cone-beam computed tomography (CBCT) images were used to evaluate the postoperative 3D changes in the proximal segments during the healing process. CBCT images were superimposed using the symphysis and the lower anterior mandible as references. Results There were no statistically significant differences between the conventional mini-plate and semi-rigid sliding plate groups (p > 0.05). With respect to the distribution of changes greater than 2 mm in the landmarks, the right condylion, right coronoid process, and left condylion showed ratios of 55.6%, 50.0%, and 44.4%, respectively, in the semi-rigid sliding plate group; however, none of the landmarks showed ratios greater than 30% in the conventional mini-plate group. Conclusions There were no statistically significant differences in postoperative changes in the segments between the conventional mini-plate and semi-rigid sliding plate groups. Nevertheless, while selecting the type of fixation technique, clinicians should consider that landmarks with greater than 2 mm changes were higher in the semi-rigid sliding plate group than in the conventional mini-plate group.