Yi-Jane Chen

The Induction of Prostaglandin E2 Production, Interleukin-6 Production, Cell Cycle Arrest, and Cytotoxicity in Primary Oral Keratinocytes and KB Cancer Cells by Areca Nut Ingredients Is Differentially Regulated by MEK/ERK Activation

There are about 200–600 million betel quid (BQ) chewers in the world. BQ chewing is one of the major risk factor of hepatocarcinoma, oropharyngeal, and esophagus cancers in Taiwan, India, and Southeast Asian countries. Thus, the precise molecular mechanisms deserve investigation. We used cultured primary keratinocytes and KB cells, RT-PCR, flow cytometry, Western blotting, and ELISA to evaluate whether alterations in early gene expression is crucial in the carcinogenic processes of BQ. We observed the induction of c-Fos mRNA expression in human gingival keratinocyte (GK) and KB carcinoma cells by areca nut (AN) extract and arecoline. A maximal increment in c-fos gene expression was shown at about 30 min after challenge. AN extract (100–800 μg/ml) and arecoline (0.1–0.8 mm) also stimulated ERK1/ERK2 phosphorylation with a maximal stimulation at 5–10 min of exposure. Pretreatment by U0126 (30 μm), a MEK inhibitor, markedly inhibited the c-Fos, cyclooxygenase-2 (COX-2), and IL-6 mRNA expression of the KB epithelial cells. In addition, U0126 and PD98059 (50 μm) also decreased AN extract- and arecoline-associated PGE2 and IL-6 production in GK and KB cells. However, U0126 by itself arrested the cells in G0/G1 phase, but was not able to prevent AN- and arecoline-induced cell death or apoptosis. In contrast, U0126 enhanced the AN-induced apoptosis of KB cells. AN ingredients thus play a significant role in the pathogenesis of oropharyngeal cancer by activation of MEK1/ERK/c-Fos pathway, which promotes keratinocyte inflammation, cell survival, and affects cell cycle progression.

Effects of Cyclic Mechanical Stretching on the mRNA Expression of Tendon/Ligament-Related and Osteoblast-Specific Genes in Human Mesenchymal Stem Cells

The purpose of this study was to explore the influences of cyclic mechanical stretching on the mRNA expressions of tendon/ligament-related and osteoblast-specific marker genes in human MSCs seeded onto a collagen type I-coated surface. The stretch-induced mRNA expressions of mesenchymal stem cell protein (MSCP), matrix metalloproteinase-3 (MMP-3), and marker genes related to tendon/ligament cells (type I collagen, type III collagen, and tenascin-C) and those typical of osteoblasts (core binding factor alpha 1 (Cbfa1), alkaline phosphatase (ALP), and osteocalcin (OCN)) were analyzed by quantitative real-time PCR. The results revealed significant downregulation of MSCP and upregulation of MMP-3 genes in MSCs subjected to mechanical loading, regardless of the magnitude of the stretching (high or low). Moreover, the typical marker genes of the osteoblast lineage were upregulated by low-magnitude stretching, whereas tendon/ligament-related genes were upregulated by high-magnitude stretching for a long period. Cbfa1 and ALP were upregulated starting as early at 8 hr, followed by a downward trend and no significant change in expression at the other time points. The mRNA expressions of type I collagen, type III collagen, and tenascin-C significantly increased in MSCs subjected to 10% stretching for 48 hr, and this effect still existed after the stretched cells had rested for 48 hr. This study demonstrated the effect of cyclic mechanical stretching on differential transcription of marker genes related to different cell lineages. Low-magnitude stretching increased mRNA expressions of Cbfa1 and ALP and was possibly involved in the early osteoblastic differentiation of MSCs, whereas high-magnitude stretching upregulated the mRNA expressions of tendon/ligament-related genes.

Maxillary Molar Intrusion with Fixed Appliances and Mini-implant Anchorage Studied in Three Dimensions

The intrusion of an overerupted maxillary molar using traditional orthodontic treatment is a real challenge. The aim of this study was to investigate the envelope of intrusive movements of a maxillary molar in cases using mini-implants as anchorage with partial or full-mouth fixed edgewise appliances. The cusp tips of the pretreatment and postintrusion dental casts were recorded by a three-dimensional (3D) digitizer. The 3D data of the serial dental casts were analyzed to distinguish the direction and magnitude of individual tooth movement. The mean intrusive movement of the maxillary first molars was three to four mm, with a maximum of over eight mm. For the adjacent maxillary second molars and second premolars, the amount of intrusion was two mm and 1-2 mm, respectively. This study demonstrated that significant true intrusion of maxillary molars could be obtained in a well-controlled manner by using fixed appliances with titanium mini-implants as bony anchorage.

Interactive effects of mechanical stretching and extracellular matrix proteins on initiating osteogenic differentiation of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are characterized by their abilities to differentiate into different lineages, including osteoblasts. Besides soluble factors, mechanical strain and extracellular matrix (ECM) proteins play important roles in osteogenic differentiation of hMSCs. However, interactions between them are still not fully understood. The purpose of this study was to investigate the combined effects of insoluble chemical and mechanical factors (ECM proteins vs. cyclic stretching) in driving hMSCs into osteogenic differentiation. To avoid the influence from osteogenic supplements, hMSCs were cultured in regular medium and subjected to cyclic mechanical stretching using a Flexcell Tension system (3% elongation at 0.1 Hz) when they were grown on substrates coated with various ECM proteins (collagen I (Col I), vitronectin (VN), fibronectin (FN), and laminin (LN)). Using alkaline phosphatase (ALP) activity and mineralized matrix deposition as respective indicators of the early and late stages of osteogenesis, we report herein that all of the ECM proteins tested supported hMSC differentiation into osteogenic phenotypes in the absence of osteogenic supplements. Moreover, cyclic mechanical stretching activated the phosphorylation of focal adhesion kinase (FAK), upregulated the transcription and phosphorylation of core‐binding factor alpha‐1 (Cbfa1), and subsequently increased ALP activity and mineralized matrix deposition. Among the ECM proteins tested, FN and LN exhibited greater effects of supporting stretching‐induced osteogenic differentiation than did Col I and VN. The ability of ECM proteins and mechanical stretching to regulate osteogenesis in hMSCs can be exploited in bone tissue engineering via approximate matrix design or application of mechanical stimulation. J. Cell. Biochem. 108: 1263–1273, 2009.

Comparison of treatment outcomes between skeletal anchorage and extraoral anchorage in adults with maxillary dentoalveolar protrusion

INTRODUCTION The goal of this retrospective cephalometric study was to compare orthodontic outcomes in patients with maxillary dentoalveolar protrusion malocclusion treated with extraoral headgear or mini-implants for maximum anchorage. MATERIALS Forty-seven subjects with Angle Class II malocclusion or Class I bimaxillary dentoalveolar protrusion were treated by retracting the maxillary dentoalveolar process by using the extraction space of the bilateral maxillary first premolars. Two anchorage systems were used. Group 1 (n = 22) received traditional anchorage preparation with a transpalatal arch and headgear; group 2 (n = 25) received mini-implants (miniplates, miniscrews, or microscrews) for bony anchorage. Pretreatment and posttreatment lateral cephalograms were superimposed to compare the following parameters between groups: (1) amount of maxillary central incisor retraction, (2) reduction in maxillary central incisor angulation, (3) anchorage loss of the maxillary first molar, (4) movements of the maxillary central incisor and first molar in the vertical direction, and (5) changes in skeletal measurements representing the anteroposterior and vertical jaw relationships. RESULTS The skeletal anchorage group had greater anterior tooth retraction (8.17 vs 6.73 mm) and less maxillary molar mesialization (0.88 vs 2.07 mm) than did the headgear group, with a shorter treatment duration (29.81 vs 32.29 months). Translational movement of the incisors was more common than tipping movement, and intrusion of the maxillary dentition was greater, in patients receiving miniplates than in those receiving screw-type bony anchorage, resulting in counterclockwise rotation of the mandible and a statistically significant decrease in the mandibular plane angle. Cephalometric analysis of skeletal measurements in patients with low to average mandibular plane angles showed no significant difference between groups, although greater maxillary incisor retraction and less mesial movement of the first molar were noted in the mini-implant group. In patients with a high mandibular plane angle, those receiving skeletal anchorage had genuine intrusion of the maxillary first molar and reduction in the mandibular plane angle, whereas those receiving headgear anchorage had extrusion of the maxillary first molar and an increase of mandibular plane angle. In contrast to the posterior movement in the headgear group, anterior movement of Point A was noted in the mini-implant group. CONCLUSIONS In both the anteroposterior and vertical directions, skeletal anchorage achieved better control than did the traditional headgear appliance during the treatment of maxillary dentoalveolar protrusion. Greater retraction of the maxillary incisor, less anchorage loss of the maxillary first molar, and the possibility of counterclockwise mandibular rotation all facilitated the correction of the Class II malocclusion.

Intrusion of the overerupted upper left first and second molars by mini-implants with partial-fixed orthodontic appliances: a case report.

Overeruption of maxillary molar(s) because of loss of the opposing teeth creates occlusal interference and functional disturbances. To restore proper occlusion, intrusion of the overerupted molars becomes essential before reconstruction can be initiated. A plausible procedure is orthodontic intrusion, which demands calibrated anchorage support from intraoral multiunit teeth and from headgear wear. In this report, we present a simplified and localized version of the orthodontic appliances in conjunction with mini-implants to intrude the overerupted molars. The purpose of using implants as skeletal anchorage was to eliminate the need for patient compliance for headgear wear and to overcome the difficulty resulting from the shortage of anchor teeth. The results showed that the biological responses of the teeth and the surrounding bony structures to the intrusion appeared normal and acceptable. Furthermore, the periodontal health and vitality of the teeth were well maintained even after a one-year follow-up.

Stability of miniplates and miniscrews used for orthodontic anchorage: experience with 492 temporary anchorage devices

OBJECTIVES The aim of this retrospective study was to evaluate systematically the potential factors that influence failure rates of temporary anchorage devices (TADs) used for orthodontic anchorage. MATERIALS AND METHODS Data on 492 TADs (miniplates, pre-drilling miniscrews, and self-drilling miniscrews) in 194 patients were collected. The factors related to TAD failure were evaluated using univariate analysis and multivariate forward stepwise logistic regression analysis. RESULTS There were no significant differences in failure rates among the TADs for the following variables: gender, type of malocclusion, facial divergency, implantation site (buccal, lingual, or crestal/midpalatal), location (anterior or posterior), method of force application (power chain or Ni-Ti coil spring), arch (upper or lower), type of soft tissue (attached gingiva or removable mucosa), and most of the cephalometric measurements that reflect dento-cranio-facial characteristics. An increased failure rate was noted for the self-drilling miniscrew type of TAD, TADs used for tooth uprighting, those inserted on bone with lower density, those associated with local inflammation of the surrounding soft tissue, those loaded within 3 weeks after insertion, and those placed in patients with greater mandibular retrusion. Failure rates of the self-drilling miniscrews installed by an oral surgeon and by an orthodontist did not differ significantly. CONCLUSIONS Inflammation of soft tissue surrounding a TAD and early loading within 3 weeks after insertion were the most significant factors predicting TAD failure. Both orthodontists and oral surgeons who install orthodontic TADs must undergo sufficient training to achieve clinical excellence.

Three-dimensional dental model analysis of treatment outcomes for protrusive maxillary dentition: Comparison of headgear, miniscrew, and miniplate skeletal anchorage

INTRODUCTION The aim of this retrospective study on dental models was to compare the orthodontic outcomes of maxillary dentoalveolar protrusion treated with headgear, miniscrews, or miniplates for maximum anchorage. METHODS The 40 subjects were diagnosed as having either Angle Class II malocclusion or Class I bimaxillary dentoalveolar protrusion. All patients were treated to retract the maxillary dentoalveolar process by using the extraction space of the bilateral maxillary first premolars. They were divided into 3 groups according to the type of anchorage used. Group 1 (n = 16) received traditional anchorage preparation with a transpalatal arch and headgear, group 2 (n = 15) received miniscrews, and group 3 (n = 9) received miniplates for skeletal anchorage. To investigate the movement of the maxillary teeth during dentoalveolar retraction, we used a 3-dimensional (3D) digitizer to assess the positional changes of the maxillary teeth relative to the stable palatal rugose structures on the serial dental models. The 3D coordinates representing pretreatment and posttreatment maxillary dental casts were superimposed to determine the movement of individual teeth from the positional changes of 18 landmarks of the central incisor, canine, second premolar, and first molar. RESULTS Three-dimensional analysis of the maxillary dental models in the buccopalatal, anteroposterior, and vertical directions showed significant differences in tooth movements between the headgear and the mini-implant (miniscrew or miniplate) groups. Both skeletal anchorage groups had greater incisor retraction (6.9 mm for the miniscrew, 7.3 mm for the miniplate) than did the headgear group (5.5 mm). Mesialization of occlusal centroid of the maxillary molar in the skeletal anchorage groups was less than that in the headgear group (1.3 mm for the miniscrew, 1.4 mm for the miniplate, 2.5 mm for the headgear). Tooth movements in the anteroposterior and buccopalatal directions did not reach a statistically significant difference between the miniscrew and miniplate groups, but the maxillary posterior teeth of the subjects receiving miniplates showed greater intrusion than those receiving miniscrews anchorage. CONCLUSIONS This 3D analysis of serial dental models demonstrated that, compared with headgear, skeletal anchorage achieved better results in the treatment of maxillary dentoalveolar protrusion. Significant intrusion of the maxillary posterior teeth was noted in the miniplate group but not in the miniscrew and headgear groups. Greater retraction of the maxillary anterior teeth, less anchorage loss of the maxillary posterior teeth, and the possibility of maxillary molar intrusion all facilitated correction of the Class II malocclusion, especially for patients with a hyperdivergent face.

Effects of thread depth, taper shape, and taper length on the mechanical properties of mini-implants

INTRODUCTION The primary stability of a mini-implant is critical, since most orthodontic mini-implant failures occur at an early stage. As orthodontic mini-implants have restrictions in diameter and length, an optimal design of the shape is important for sufficient primary stability. The purpose of this study was to investigate the influence of various mini-implants design factors, including thread depth, degree of taper, and taper length on insertion torque, pullout strength, stiffness, and screw displacement before failure. METHODS Finite element analyses were conducted first for identification of optimal design parameters. Four types of mini-implants with different design parameters were then custom manufactured and tested mechanically. All mechanical tests were performed in artificial bone with homogenous density to remove the variability associated with bone. RESULTS Finite element results showed that, for mini-implants with a fixed external diameter of 2 mm, a thread length of 9.82 mm, and a pitch of 0.75 mm, those with greater thread depths, smaller taper degrees, and shorter taper lengths generated higher maximum stresses on the bone and thread elements. These mini-implants also had larger relative displacements. Maximum pullout resistance was attained with a core/external diameter ratio of 0.68. All mechanical results were compatible with the findings in the finite element analyses. CONCLUSIONS Modification of the mini-implant design can substantially affect the mechanical properties. The finite element method is an effective tool to identify optimal design parameters and allow for improved mini-implant designs.

Radiographic Assessment of Skeletal Maturation Stages for Orthodontic Patients: Hand-wrist Bones or Cervical Vertebrae?

BACKGROUND/PURPOSE The skeletal maturation status of a growing patient can influence the selection of orthodontic treatment procedures. Either lateral cephalometric or hand-wrist radiography can be used to assess skeletal development. In this study, we examined the correlation between the maturation stages of cervical vertebrae and hand-wrist bones in Taiwanese individuals. METHODS The study group consisted of 330 male and 379 female subjects ranging in age from 8 to 18 years. A total of 709 hand-wrist and 709 lateral cephalometric radiographs were analyzed. Hand-wrist maturation stages were assessed using National Taiwan University Hospital Skeletal Maturation Index (NTUH-SMI). Cervical vertebral maturation stages were determined by the latest Cervical Vertebral Maturation Stage (CVMS) Index. Spearmans rank correlation was used to correlate the respective maturation stages assessed from the hand-wrist bones and the cervical vertebrae. RESULTS The values of Spearmans rank correlation were 0.910 for males and 0.937 for females, respectively. These data confirmed a strong and significant correlation between CVMS and NTUH-SMI systems (p less than 0.001). After comparison of the mean ages of subjects in different stages of CVMS and NTU-SMI systems, we found that CVMS I corresponded to NTUH-SMI stages 1 and 2, CVMS II to NTUH-SMI stage 3, CVMS III to NTUHSMI stage 4, CVMS IV to NTUH-SMI stage 5, CVMS V to NTUH-SMI stages 6, 7 and 8, and CVMS VI to NTUH-SMI stage 9. CONCLUSION Our results indicate that cervical vertebral maturation stages can be used to replace hand-wrist bone maturation stages for evaluation of skeletal maturity in Taiwanese individuals.