Atp6i deficient mouse model uncovers transforming growth factor-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation / 国际口腔科学杂志·英文版

The biomolecular mechanisms that regulate tooth root development and odontoblast differentiation are poorly understood. We found that Atp6i deficient mice (Atp6i-/-) arrested tooth root formation, indicated by truncated Hertwig's epithelial root sheath (HERS) progression. Furthermore, Atp6i deficiency significantly reduced the proliferation and differentiation of radicular odontogenic cells responsible for root formation. Atp6i-/- mice had largely decreased expression of odontoblast differentiation marker gene expression profiles (Col1a1, Nfic, Dspp, and Osx) in the alveolar bone. Atp6i-/- mice sample RNA-seq analysis results showed decreased expression levels of odontoblast markers. Additionally, there was a significant reduction in Smad2/3 activation, inhibiting transforming growth factor-β (TGF-β) signaling in Atp6i-/- odontoblasts. Through treating pulp precursor cells with Atp6i-/- or wild-type OC bone resorption-conditioned medium, we found the latter medium to promote odontoblast differentiation, as shown by increased odontoblast differentiation marker genes expression (Nfic, Dspp, Osx, and Runx2). This increased expression was significantly blocked by anti-TGF-β1 antibody neutralization, whereas odontoblast differentiation and Smad2/3 activation were significantly attenuated by Atp6i-/- OC conditioned medium. Importantly, ectopic TGF-β1 partially rescued root development and root dentin deposition of Atp6i-/- mice tooth germs were transplanted under mouse kidney capsules. Collectively, our novel data shows that the prevention of TGF-β1 release from the alveolar bone matrix due to OC dysfunction may lead to osteopetrosis-associated root formation via impaired radicular odontoblast differentiation. As such, this study uncovers TGF-β1 /Smad2/3 as a key signaling pathway regulating odontoblast differentiation and tooth root formation and may contribute to future therapeutic approaches to tooth root regeneration.

Clear aligner therapy: risks and clinical strategies / 中华口腔医学杂志

Clear aligner, as a transparent and removable appliance, offers an alternative to conventional fixed appliance to patients with high demands for esthetics and comfort. Meanwhile, the rapid development of materials and techniques has made clear aligner more widely used in orthodontics. However, there are still several concerns and risks in clinical practice of clear aligners, which may result in unfavorable outcomes. Herein, we have discussed the clinical risks of clear aligner therapy, and provided some targeted strategies, in order to promote the clinical application of clear aligners.

Use of autonomous maximal smile to evaluate dental and gingival exposure / 대한치과교정학회지

OBJECTIVE: This study was performed to validate the autonomous maximal smile (AMS) as a new reference for evaluating dental and gingival exposure. METHODS: Digital video clips of 100 volunteers showing posed smiles and AMS at different verbal directives were recorded for evaluation a total of three times at 1-week intervals. Lip-teeth relationship width (LTRW) and buccal corridor width (BCW) were measured. LTRW represented the vertical distance between the inferior border of the upper vermilion and the edge of the maxillary central incisors. Intraclass correlation coefficients (ICCs) for reproducibility, and the m-value (minimum number of repeated measurements required for an ICC level over 0.75), were calculated. RESULTS: LTRW and BCW of the AMS were 1.41 and 2.04 mm, respectively, greater than those of the posed smile (p < 0.05), indicating significantly larger dental and gingival exposure in the AMS. The reproducibility of the AMS (0.74 to 0.77) was excellent, and higher than that of the posed smile (0.62 to 0.65), which had fair-to-good reproducibility. Moreover, the m-value of the AMS (0.88 to 1.05) was lower than that of the posed smile (1.59 to 1.85). CONCLUSIONS: Compared to the posed smile, the AMS shows significantly larger LTRW and BCW, with significantly higher reproducibility. The AMS might serve as an adjunctive reference, in addition to the posed smile, in orthodontic and other dentomaxillofacial treatments.

A review of the effectiveness and long-term stability of the functional appliance / 中华口腔医学杂志

The orthopedic treatment of the orthodontics is a typical and crucial technique and method that uses functional appliances to fully work out the potentials of the jaws and muscles, and accordingly to correct the functional or mild skeletal malocclusions in pre-pubertal children and adolescents. A successful orthopedic treatment involves its short-time effectiveness and its long-term stability. For many years, however, the effectiveness of the functional appliance is controversial and the long-term stability of the functional appliance has always been overlooked. Thus, with an aim of presenting guidelines on orthopedic treatment, the effectiveness and the long-term stability of the functional appliance are discussed in this article.

Effect of inserted angle on the stability of loaded microscrews / 中华口腔医学杂志

Objective@#To evaluate the effect of different insertion angles on the osseointegration of loaded microscrews in beagle jaws.@*Methods@#Forty-eight microscrews were inserted at four different angles (30°, 50°, 70° and 90°) into the interradicular zones between the mandibular first molar and third premolar in twelve beagles and the microscrews had been loaded with a force of 2 N immediately for 8 weeks. After microscrew-bone specimens fixed, the maximum output value (Fmax) of pull-out test was recorded and the histomorphological changes of hard tissue were observed. The bone-implant contact (BIC%) was quantitatively analyzed and the osseointegration of microscrew-bone interface was comprehensively evaluated.@*Results@#Both Fmax and BIC% values of microscrews were influenced by the insertion angles. The maximum value of Fmax was (385±23) N in the group with 50° angle, and the minimum value was (198±16) N in the group with 30° angle(P <0.05). The maximum value of BIC% was (59.1±6.0)% in the group with 70° angle, and the minimum value was (30.2±3.2)% in the group with 30° angle (P <0.05). Histomorphology observation revealed that in peri-screws region, the various degree of bone remodeling was found in different angle samples.@*Conclusions@#The insertion angles (50°and 70°) were favorable to the stability of the microscrew.

Invisible orthodontics: clear aligners and customized lingual appliances / 中华口腔医学杂志

In recent years, invisible orthodontics has been one of the concerns of both orthodontists and patients. As two types of invisible orthodontics, clear aligners fit for cases that have high demand for living quality, need distalization of molars or intrusion of incisors, suffer from severe periodontitis, or that have non-abundant time for visits. While customized lingual appliances fit for cases that have high demand for aesthetics, have deep overbite or complex malocclusion, need maxillary expansion or retraction of incisors, or that have low compliance and good economic conditions. Based on aspects of clinical application, this article presents the characteristics of these two types of invisible orthodontics, in order to provide reference for individualized options according to different situations.

Effects of pulsed ultrasound and pulsed electromagnetic field on the extracellular matrix secretion of rat bone marrow mesenchymal stem cell pellets in chondrogenesis / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the effects of pulsed ultrasound (PUS) and pulsed electromagnetic fields (PEMF) on the secretion of extracellular matrix from a culture complex during in vitro chondrogenesis.</p><p><b>METHODS</b>All the rat bone marrow mesen- chymal stem cell pellets were cultured in achondrogenic medium. Different intensities of PUS (100, 150, and 200 mW · cm⁻²) and PEMF (1, 2, and 5 mT) were applied to the cell pellets for 2 weeks. Group N was cultured without PUS and PEMF stimu- lation as control. The culture medium was collected after 2 weeks of culture. Enzyme-linked immunosorbent assay (ELISA) was used to detect the type of collagen and glycosaminoglycan (GAG) in the culture medium.</p><p><b>RESULTS</b>PUS increased the secreting-type collagen and GAG from cell pellets compared with group N (P < 0.05), whereas there was no difference in different intensities (P > 0.05). PEMF had no significant effect on the secretion of the type of collagen (P > 0.05). A PEMF of 1 mT had no significant effect on the secretion of GAG (P > 0.05). A PEMF 2 and 5 mT decreased the secretion of GAG (P < 0.05).</p><p><b>CONCLUSION</b>To prevent the secretary of extracellular matrix may play a role in chondrogenic effect of PEMF.</p>

Histological changes of pure titanium micro-implant under inflammatory stimulation and orthodontic force as well as bone remodeling / 中国组织工程研究

BACKGROUND:Implant stability is mainly influenced by peri-implant inflammatory stimulation. OBJECTIVE:To build a beagle model of peri-implantitis under orthodontic force and to observe the bone remodeling of the Beagle dog model. METHODS: Micro-implants were randomly implanted into the maxilary interradicular region at the center of the mesial and distal roots of bilateral P2, P3, P4 and M1 of Beagle dogs. One side served as a loaded micro-implant with peri-implantitis under 100 g of orthodontic force at 1, 2, 3, 4 weeks of peri-implantitis, and the force lasted for 1 month. After that, the animals were kiled to prepare specimens with micro-implants. Bone-to-implant contacts were calculated and histological changes of the bone interface under continuous orthodontic force at different stages of peri-implantitis were observed under light microscope. RESULTS AND CONCLUSION:There were a large number of inflammatory cels after micro-implants were implanted with silk thread ligation to the cervical part. Over time, inflammatory cels were gradualy diffused to the tip of micro-implant, and there were a great quantity of colagenous fibers, osteocytes and active bone remodeling. When the inflammation was diffused to the tip of micro-implant after 2 weeks of peri-implantitis, woven bones composed of newly formed trabeculae appeared, and imflammatory cels dispersed. The medulary cavity was irregular after colagen fibrils absorption, and there were 3-4 layers of osteoblasts in the bone lacunae, with active bone formation. These findings indicate that the Beagle model of pure titanium peri-implantitis under orthodontic force was successfuly built in the experiment, and bone formation became active at 2 weeks after modeling.

Application of Typodont-based table clinic competition in undergraduate orthodontic educa-tion / 中华医学教育探索杂志

Objective To evaluate the effectiveness of Typodont-based table clinic competition (TCC) on undergraduate orthodontic education. Methods Students who have finished basic orthodon-tic courses made diagnosis,treatment strategy and performed orthodontic treatment for malocclusion cases on Typodonts. A self-design questionnaire was employed to investigate their perception to this pedagogy. Results The majority of participants(82.2%-92.9%) highly evaluated Typodont-based TCC. Conclu-sions Typodont-based TCC course is conducive to arousing students' study internets and to promoting association between theory and practice.

Research progress on gene involved in tooth agenesis / 华西口腔医学杂志

Tooth agenesis, belonging to the abnormal tooth development, is a common disease in clinic. The disease not only affects the person's chewing function, but also influences the pronunciation, appearance and mental health. In the past, genetic linkage and molecular biology research have made clear of part of the genetic mutations' sites of the syndromic and non-syndromic tooth agenesis. Although the mechanism was not clear yet, but the important mutations are now known to be involved in many factors. Thesyndromic and non-syndromic tooth agenesis related gene are reviewed in this paper.

Histopathological study on the healing of orthodontic implant-bone interface adjacent to extraction / 华西口腔医学杂志

<p><b>OBJECTIVE</b>Osseointegration of orthodontic microscrew implant is influenced by tooth extraction. This study aims to evaluate the safety margin of the osseointegration of orthodontic implants by investigating the healing process of the implant-bone interface through histopathological studies and quantitative determination.</p><p><b>METHODS</b>Twelve male beagles were selected and randomly divided into four groups. An orthodontic microscrew was implanted beside the tooth extraction area. Animals were killed in 1, 3, 8, and, 12 weeks to investigate tissue response. Histomorphological observation and bone implant contact ratio (BIC) tests were performed at different healing time after implantation.</p><p><b>RESULTS</b>A new bone was formed on the implant-bone interface of the control group. Bone resorptions were also detected in the experimental group 3 weeks after implantation. The BIC level of the control groups increased during the first 8 weeks; no change was observed anymore after the 8th week. On the other hand, the BIC value in the experimental group decreased in the first 3 weeks. It then increased rapidly and reached its peak of 80.08% in the 8th week. No significant difference wa s found between the experimental and control groups in the first 3 weeks. After the 3rd week, the BIC value of the experimental group (44.35%) was lower than that of the control group (55.46%) (P < 0.01).</p><p><b>CONCLUSION</b>The healing process after implantation was influenced by tooth extraction. Bone resorption was detected at an early stage. However, vigorous bone remodeling was observed subsequently.</p>

Vertical changes in class I malocclusion between 2 different extraction patterns

To compare vertical changes occurring in Class I patients after orthodontic treatment with different extraction patterns in a retrospective study. Records of 47 patients with extraction of maxillary first premolars and mandibular second premolars [4/5, Group A] and 46 patients with extraction of fourth first premolars [4/4, Group B] were obtained in the Orthodontic Department, West China Hospital of Stomatology, Chengdu, Sichuan, China from April 2008 to July 2012. Pretreatment and posttreatment cephalograms were digitized, 8 skeletal and 10 dental cephalometric measurements were selected to evaluate vertical changes. Changes of measurements resulting from orthodontic treatment in each group were compared by paired t-test; changes between 2 groups were compared by Independent t-test. Before treatment, subjects in Group A showed larger angle formed by the intersection of NA and NB lines, overjet, and overbite than those in Group B. After treatment, both groups showed significant vertical changes after orthodontic treatment without remarkable differences between groups. No differences of vertical change were found between the 2 extraction patterns. The hypothesized wedge effects due to mesial movement of posterior teeth might be balanced by the extrusion of posterior teeth as well as the residual growth potentials

The relationship between c-fos gene and filamentous actin cytoskeleton in MG-63 osteoblasts under cyclic tensile stress / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the relationship between c-fos gene and filamentous actin (F-actin) in MG-63 osteoblasts under cyclic tensile stress.</p><p><b>METHODS</b>MG-63 osteoblasts were subjected to cyclic tensile stress (0.5 Hz, 2 000 microstrain) for 3, 6, and 12 h. The changes of c-fos gene were investigated by fluorescent quantitation polymerase chain reaction. Then the best loading time group was screened as the experimental group compared with 0 h group. The changes of F-actin and c-fos were investigated with or without cytochalasin D treatment.</p><p><b>RESULTS</b>Cyclic tensile stress induced high expression of c-fos mRNA, and peaked at 3 h. After loading, F-actin had a structure reorganization, but had no change in expression. After cytochalasin D treatment, the formation of stress fibers and the fluorescence intensity of F-actin cytoskeleton significantly reduced, meanwhile the c-fos mRNA expression was inhibited.</p><p><b>CONCLUSION</b>After loading, there is only structure reorganization for F-actin, and the expression has not any change. That means the remodeling F-actin is the existing one. F-actin reorganization is an important part in c-fos gene expression induced by stress.</p>

A gate spring which can torque an individual tooth with high efficiency / 华西口腔医学杂志

It is to address torquing an individual tooth using a gate spring. The gate spring is made of a rectangular stainless steal wire, in the shape of a gate, which is incorporated to the archwire by spot welding. Torque is generated by the combined effects of the gate spring and the archwire. After 2-3 months, the gate spring can obviously torque individual tooth.

A pilot study on changes of posterior available spaces in mandible dentitions for adolescents between the ages of 11 and 20 years in Chengdu area / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to study the changes of available spaces of posterior arch segments in mandible dentitions (ASPAS) from ages of 11 to 20 years, which would provide information on normal growth and development of the dental arches in teenagers in Chengdu area.</p><p><b>METHODS</b>The data were derived from systematically collected preorthodontic lateral cephalograms of 526 patients, including 232 males and 294 females from the Orthodontic Department of West China College of Stomatology, Sichuan University during the period of 1999-2000 (aged 11-20 years). The values of ANB angle, FH-MP, ASPAS were obtained using the cephalometric analysis. Afterwards, the growth changes of ASPAS from the subjects and their correlations with age, gender, angle malocclusion types and vertical skeletal patterns were analyzed.</p><p><b>RESULTS</b>ASPAS was related to age and class II angle malocclusion. Though gender was not associated with ASPAS, significant differences in curves of ASPAS were found between males and females. The growth changes of ASPAS in the patients with skeletal Class III malocclusion were more obvious than in patients with Class I and II malocclusion.</p><p><b>CONCLUSION</b>Our results reveal that significant differences were demonstrated in growth change values in posterior available spaces of patients with different races and angle malocclusion types.</p>

Effects of Fränkel II appliance on sagittal dimensions of upper airway in children / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to investigate the effects of Fränkel II appliance on the upper airway of children.</p><p><b>METHODS</b>The subjects consisted of 20 patients with Angle Class II, division I malocclusion (10 males and 10 females). The ages of all cases were ranged in 9-10 years. Each experimental subject was also served as self-control and cephalometric analysis was conducted.</p><p><b>RESULTS</b>Compared with the results of pretreatment, the distance of PNS-Ba, SPP-SPPW, P-T, V-LPW and the Mcnamara line increased remarkably.</p><p><b>CONCLUSION</b>The Fränkel II appliance can improve the sagittal dimensions of the upper airway in children.</p>

Comparison of craniofacial skeletal structures in adult high-angle and low-angle facial skeletal types / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to compare the differences of craniofacial characteristics of adult high-angle and low-angle facial skeletal types.</p><p><b>METHODS</b>The subjects consisted of 37 yellow race adults (17 high-angle, 20 low-angle). Fifty-three items of cephlometic radiographs were analyzed.</p><p><b>RESULTS</b>The angle of N-S-Ar and N-S-Ba, the distance of Ptm-A, Co-Go, Po-NB, and S-Go, and the thickness of the mandibular symphysis in high-angle group were smaller than these in low-angle group. The angles of SN-OP, FH-OP, PP-OP, SN-MP, FH-MP, PP-MP, S-Ar-Go, mandibular angle(Ar-Go-Me), Y-angel and SUM, the distance of S-Co, N-Me, and ANS-Me in high-angle group were greater than these in low-angle group. The index of FHI, N-ANS/N-Me, and N-ANS/ANS-Me were smaller, and ANS-Me/N-Me larger in high-angle group. Although the means of Go-Po and FH-RP were smaller in high angle group, but no statistical difference were found.</p><p><b>CONCLUSION</b>The craniofacial morphology of adult high-angle and low-angle facial skeletal types demonstrated significant differences, especially in lower facial form.</p>

Establishment of normal value of posterior arch length of adolescence in Chengdu / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu.</p><p><b>METHODS</b>The samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject.</p><p><b>RESULTS</b>The normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially.</p><p><b>CONCLUSION</b>The data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.</p>