• The korean journal of orthodontics
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• v.53 no.4
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• pp.219-231
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• 2023

Objective: This study aimed to clarify differences in the positions of cone-beam computed tomography (CBCT) landmarks according to different midsagittal planes (MSPs) in patients with skeletal Class III facial asymmetry. Methods: Pre-treatment CBCT data from 60 patients with skeletal Class III were used. The patients were classified into symmetric (menton deviations of < 2 mm) or asymmetric (menton deviations of > 4 mm) groups. Six MSPs were established based on previous studies, and three-dimensional analyses were performed for the planes in both the groups. The measurement outcomes were compared statistically. Results: A statistically significant interaction (p < 0.01) was observed between MSPs and facial asymmetry. No significant differences were observed among MSPs in the symmetric group. However, significant differences in linear measurements were identified among MSPs in the asymmetric group. Specifically, the upper facial MSP revealed both maxillary and mandibular transverse asymmetries. On the other hand, anterior nasal spine (ANS)-associated MSP could not identify maxillary asymmetry. Furthermore, the menton deviation was approximately 3 mm lower when estimated using the ANS-associated MSP than that using upper facial MSP. Conclusions: The choice of MSP can significantly affect treatment outcomes while diagnosing patients with asymmetry. Therefore, care should be taken when selecting MSP in clinical practice.

• The korean journal of orthodontics
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• v.54 no.4
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• pp.257-263
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• 2024

Objective: Lingual fixed retainers, made from 0.0175-inch 3-strand twisted stainless steel wire (TW) and 0.016 × 0.022-inch straight rectangular wire (RW), are generally used in clinical practice. This study aimed to calculate their accuracy by comparing the discrepancy between computer-aided customized retainers made from these two types of wires. Methods: Eleven orthodontic patients were selected, resulting in 22 maxillary and mandibular three-dimensional printing dental models. Two types of lingual fixed retainers were bonded from canine to canine. To determine the accuracy, five points were chosen for each model, resulting in 110 selected points. The absolute values of the distances on the x-, y-, and z-axes were measured to compare the accuracy of the two types of computer-aided retainers. Results: The accuracy of the two types of retainers did not differ significantly in the x- and z-axes, but only in the y-axis (P < 0.01), where RW-fixed retainers exhibited a slightly but significantly increased distance compared to the TW. Conclusions: Both types of retainers showed high accuracy; however, RW had a slight but statistically significant difference along the y-axis compared with TW. This type of computer-aided design/computer-aided manufacturing bending machine is limited to two dimensions, and the dental arch is curved. Therefore, RW may require slight manual adjustment by the practitioner after manufacturing.

• Natural Product Sciences
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• v.11 no.1
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• pp.45-49
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• 2005

Previously, a flavonoid fraction, which consisted mainly of protocatechuic acid, fustin, fisetin, sulfuretin, and butein, here named RCMF [${\underline{R}}hus$ verniciflua Stokes (RVS) ${\underline{c}}hloroform-{\underline{m}}ethanol\;{\underline{f}}raction$], was prepared from a crude acetone extract of RVS which is traditionally used as a food additive and as an herbal medicine. In the present study, we investigated the effects of $TNF-{\alpha}$ on RCMF-induced growth inhibition and apoptosis induction using human osteosarcoma (HOS) cells. The results from tritium uptake and MTT assays showed that $TNF-{\alpha}$ treatment itself (10 ng/ml) did not induce any cytotoxicity, but it actively accelerated RCMF-mediated cytotoxicity of HOS cells. RCMF-induced cytotoxicity and its facilitation by $TNF-{\alpha}$ was verified to be apoptotic, based on the increased DNA fragmentation and low fluorescence intensity in nuclei after propidium iodide (PI) staining of HOS cells. This speculation was further demonstrated by monitoring the Annexin V/PI double staining which could discriminate the difference between apoptotic and necrotic deaths. Collectively, our findings indicate that $TNF-{\alpha}$ accelerates RCMF-induced cytotoxicity in HOS cells.

• Natural Product Sciences
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• v.11 no.3
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• pp.139-144
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• 2005

Bioflavone quercetin is believed to play an important role preventing bone loss by affecting osteoclastogenesis and regulating many systemic and local factors including hormones and cytokines. This study examined how quercetin acts on tumor necrosis factor-alpha ($TNF-{\alpha}$)-mediated apoptosis in MC3T3-E1 osteoblastic cells. Apoptosis assays revealed the dose-dependent acceleration of quercetin on $TNF-{\alpha}-induced$ apoptosis in MC3T3-E1 cells, which was demonstrated by the increased number of positively stained cells in the trypan blue staining and TUNEL assay, and the migration of many cells to the $sub-G_0/G_1$ phase in flow cytometric analysis. In particular, quercetin treatment alone increased the expression of p53 and p21 proteins in the cells. Consequently, this study showed that quercetin accelerates the $TNF-{\alpha}-induced$ apoptosis in MC3T3-E1 osteoblastic cells.

• International Journal of Oral Biology
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• v.34 no.4
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• pp.199-203
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• 2009

This study investigated whether orthodontic force influences the production of osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL) in vivo, both of which are affected by cortical activation. Mechanical force was applied to the maxillary premolars of orthodontic patients by fitting the transpalatal arch prior to cortical activation of the gingival tissue. Gingival crevicular fluid (GCF) samples were then collected from each patient using paper strips before and after 1, 3, 7 or 14 days of treatment. The OPG and RANKL levels in the GCF were determined by enzyme-linked immunosorbent assays. The levels of OPG were significantly increased after 1 day of fitting the appliance and decreased to basal levels at 3 days after fitting. In contrast, the RANKL levels were dramatically decreased at 1 day after fitting, but recovered to those of the untreated control at 3 days after the force application. The force-mediated changes in the OPG and RANKL levels of the GCF were unaffected by cortical activation during these experimental periods. Collectively, these results suggest that an acute and severe change between the OPG and RANKL levels plays an important role in stimulating the cellular responses required for alveolar bone remodeling by orthodontic treatment.

• Imaging Science in Dentistry
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• v.43 no.2
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• pp.85-90
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• 2013

Purpose: This study was performed to determine the buccal alveolar bone thickness following rapid maxillary expansion (RME) using cone-beam computed tomography (CBCT). Materials and Methods: Twenty-four individuals (15 females, 9 males; 13.9 years) that underwent RME therapy were included. Each patient had CBCT images available before (T1), after (T2), and 2 to 3 years after (T3) maxillary expansion therapy. Coronal multiplanar reconstruction images were used to measure the linear transverse dimensions, inclinations of teeth, and thickness of the buccal alveolar bone. One-way ANOVA analysis was used to compare the changes between the three times of imaging. Pairwise comparisons were made with the Bonferroni method. The level of significance was established at p<0.05. Results: The mean changes between the points in time yielded significant differences for both molar and premolar transverse measurements between T1 and T2 (p<0.05) and between T1 and T3 (p<0.05). When evaluating the effect of maxillary expansion on the amount of buccal alveolar bone, a decrease between T1 and T2 and an increase between T2 and T3 were found in the buccal bone thickness of both the maxillary first premolars and maxillary first molars. However, these changes were not significant. Similar changes were observed for the angular measurements. Conclusion: RME resulted in non-significant reduction of buccal bone between T1 and T2. These changes were reversible in the long-term with no evident deleterious effects on the alveolar buccal bone.

• The korean journal of orthodontics
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• v.43 no.6
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• pp.279-287
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• 2013

Objective: To investigate the dentoskeletal factors which may predict soft-tissue chin strain during lip closure. Methods: The pretreatment frontal and lateral facial photographs and lateral cephalograms of 209 women (aged 18-30 years) with Angle's Class I or II malocclusion were examined. The subjects were categorized by three examiners into the no-strain and strain groups according to the soft-tissue chin tension or deformation during lip closure. Relationships of the cephalometric measurements with the group classification were analyzed by logistic regression analysis, and a classification and regression tree (CART) model was used to define the predictive variables for the group classification. Results: The lower the value of the overbite depth indicator (ODI) and the higher the values of upper incisor to Nasion-Pogonion (U1-NPog, mm), overjet, and upper incisor to upper lip (U1-upper lip, mm), the more likely was the subject to be classified into the strain group. The CART showed that U1-NPog was the most prominent predictor of soft-tissue chin strain (cut-off value of 14.2 mm), followed by overjet. Conclusions: To minimize strain of the soft-tissue chin, orthodontic treatment should be oriented toward increasing the ODI value while decreasing the U1-NPog, overjet, and U1 upper lip values.

• The korean journal of orthodontics
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• v.36 no.1 s.114
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• pp.84-90
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• 2006

The aims of this study were to investigate the prevalence of spaced, closed, and crowded primary dentitions by sex and arch in Korean children from Kanghwa, and to determine the frequency of the primate and developmental spaces. The differences in the mesiodistal crown diameters and the arch dimensions between the spaced, closed, and crowded primary dentitions were also evaluated. Dental casts of 102 preschool children (57 males and 45 females, aged $4{\sim}5$ years) were studied. The prevalence of spacing in the primary dentition was 63.2% In males and 57.8% in females. The frequency of spacing was greater in males than in females, and greater in the maxillary arch than in the mandibular arch. The crowns were significantly larger and the arches significantly narrower in closed and crowded dentitions than in those with spacing (p<0.05). The results showed that the prevalence of spacing was lower than that found in previous studies and the presence of spacing in the anterior region was related to the mesiodistal crown diameter and the intercanine width.

• The korean journal of orthodontics
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• v.42 no.6
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• pp.291-296
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• 2012

Objective: The purposes of this study were to measure the palatal soft tissue thickness at popular placement sites of temporary anchorage devices (TADs) by cone-beam computed tomography (CBCT) and evaluate the age, gender, and positional differences in this parameter. Methods: The study sample consisted of 23 children (10 boys and 13 girls; mean age, $10.87{\pm}1.24$ years; range, 6.7 to 12.6 years) and 27 adults (14 men and 13 women; mean age, $21.35{\pm}1.14$ years; range, 20.0 to 23.8 years). Nine mediolateral and nine anteroposterior intersecting reference lines were drawn on CBCT scans of the 50 subjects, and the resultant measurement areas were designated according to their mediolateral (i.e., lateral, medial, and sutural) and anteroposterior (i.e., anterior, middle, and posterior) positions. Repeated-measures analysis of variance was performed to analyze intragroup and intergroup differences. Results: No significant age and gender differences were found (p = 0.309 and 0.124, respectively). Further, no significant anteroposterior change was observed (p = 0.350). However, the lateral area presented the thickest soft tissue whereas the sutural area had the thinnest soft tissue (p < 0.001). Conclusions: Clinical selection of the placement sites of TADs should be guided by knowledge of the positional variations in the palatal soft tissue thickness in addition to other contributing factors of TAD stability.

• Imaging Science in Dentistry
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• v.47 no.2
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• pp.117-122
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• 2017

Purpose: The aim of this study was to compare the use of 3-dimensional (3D) laser scanning and cone-beam computed tomography (CBCT) as methods of root surface measurement. Materials and Methods: Thirty teeth (15 maxillary first premolars and 15 mandibular first premolars) from 8 patients who required extractions for orthodontic treatment were selected. Before extraction, pre-treatment CBCT images of all the patients were recorded. First, a CBCT image was imported into simulation software (Mimics version 15.01; Materialise, Leuven, Belgium) and the root surface area of each tooth was calculated using 3-Matic (version 7.01, Materialise, Leuven, Belgium). After extraction, all the teeth were scanned and the root surface area of each extracted tooth was calculated. The root surface areas calculated using these 2 measurement methods were analyzed using the paired t-test (P<.05). Correlations between the 2 methods were determined by calculating the Pearson correlation coefficient. The intraclass correlation coefficient(ICC) was used to assess intraobserver reliability. Results: The root surface area measurements ($230.11{\pm}41.97mm^2$) obtained using CBCT were slightly greater than those ($229.31{\pm}42.46mm^2$) obtained using 3D laser scanning, but not significantly (P=.425). A high Pearson correlation coefficient was found between the CBCT and the 3D laser scanner measurements. The intraobserver ICC was 1.000 for 3D laser scanning and 0.990 for CBCT. Conclusion: This study presents a novel CBCT approach for measuring the root surface area; this technique can be used for estimating the root surface area of non-extracted teeth.