Orthodontic traction of a deeply impacted mandibular first molar via a ramus miniscrew through lateral-window technique: A case report.

BACKGROUND: The incidence of mandibular first molar impaction is less than 0.01%, and there are no standard treatment guidelines. Orthodontic traction can be chosen as a treatment plan in some circumstances. One miniscrew in the mandibular ramus can offer sufficient anchorage for the traction of impacted mandibular molars. CASE DESCRIPTION: A 10-year-old boy had a completely labially positioned maxillary left canine and a deeply impacted mandibular left first molar associated with a dentigerous cyst. Using 2 palatal miniscrews for distalization, space was created to align the maxillary left canine. In addition, a miniscrew in the mandibular ramus facilitated the traction of the mandibular left first molar. After 3 years and 6 months of orthodontic treatment, the integrity of the dental arch was restored, and occlusal function was reestablished. PRACTICAL IMPLICATIONS: A ramus miniscrew is an effective and viable treatment option for the orthodontic traction of deeply impacted mandibular molars.

The EDA/EDAR/NF-κB pathway in non-syndromic tooth agenesis: A genetic perspective.

Non-syndromic tooth agenesis (NSTA) is one of the most common dental developmental malformations affected by genetic factors predominantly. Among all 36 candidate genes reported in NSTA individuals, EDA, EDAR, and EDARADD play essential roles in ectodermal organ development. As members of the EDA/EDAR/NF-κB signaling pathway, mutations in these genes have been implicated in the pathogenesis of NSTA, as well as hypohidrotic ectodermal dysplasia (HED), a rare genetic disorder that affects multiple ectodermal structures, including teeth. This review provides an overview of the current knowledge on the genetic basis of NSTA, with a focus on the pathogenic effects of the EDA/EDAR/NF-κB signaling pathway and the role of EDA, EDAR, and EDARADD mutations in developmental tooth defects. We also discuss the phenotypic overlap and genetic differences between NSTA and HED. Ultimately, this review highlights the importance of genetic analysis in diagnosing and managing NSTA and related ectodermal disorders, and the need for ongoing research to improve our understanding of these conditions.

Radiographic Features of Mandibular Second Molars with Eruption Disturbances: A Retrospective Study.

We aimed to establish the characteristics and potential etiological risk factors of eruption disturbances in mandibular second molars (MM2). We retrospectively enrolled patients with eruption disturbances in MM2. A total of 143 MM2 with eruption disturbances from 112 patients (mean age 17.45 ± 6.35) were included in this study. Panoramic radiographs were employed to determine the risk factor, angulation type, impaction depth, tooth development stage, and associated pathology. The novel classification method of MM2 was based on impaction depth and angulation. Of 143 MM2, 137 and 6 were diagnosed with impaction and retention, respectively. Insufficient space was the most frequent risk factor for eruption disturbances. There were no significant differences between retention and impaction regarding sex, age, or side. The most frequent impaction type was Type I. The most frequent angulation of impacted MM2 was mesioangular. Impacted MM2 with shallower depth were more frequently associated with the presence of first molar undercut. Impaction types did not differ according to age, side, development stage, or distance from the MM1 distal surface to the anterior border of the ramus. Dentigerous cysts were associated with earlier MM2 development stages and greater MM2 depth. In conclusion, MM2 impaction types differed according to the risk factor, angulation type, MM1 undercut, and presence of cysts. Early MM2 development stage and greater MM2 depth were risk factors for MM2 eruption disturbances with cysts.

Association of Body Mass Index (BMI) with Lip Morphology Characteristics: A Cross-Sectional Study Based on Chinese Population.

BACKGROUND: Lip morphology is essential in diagnosis and treatment of orthodontics and orthognathic surgery to ensure facial aesthetics. Body mass index (BMI) has proved to have influence on facial soft tissue thickness, but its relationship with lip morphology is unclear. This study aimed to evaluate the association between BMI and lip morphology characteristics (LMCs) and thus provide information for personalized treatment. METHODS: A cross-sectional study consisted of 1185 patients from 1 January 2010 to 31 December 2020 was conducted. Confounders of demography, dental features, skeletal parameters and LMCs were adjusted by multivariable linear regression to identify the association between BMI and LMCs. Group differences were evaluated with two-samples t-test and one-way ANOVA test. Mediation analysis was used for indirect effects assessment. RESULTS: After adjusting for confounders, BMI is independently associated with upper lip length (0.039, [0.002-0.075]), soft pogonion thickness (0.120, [0.073-0.168]), inferior sulcus depth (0.040, [0.018-0.063]), lower lip length (0.208, [0.139-0.276]), and curve fitting revealed non-linearity to BMI in obese patients. Mediation analysis found BMI was associated with superior sulcus depth and basic upper lip thickness through upper lip length. CONCLUSIONS: BMI is positively associated with LMCs, except for nasolabial angle as negatively, while obese patients reverse or weaken these associations.

Microglia activation and temporal changes in rat model of trigeminal neuralgia.

OBJECTIVES: This study aimed to investigate whether the microglia in the spinal trigeminal nucleus caudal part (Sp5C) were activated in a rat model of trigeminal neuralgia and to explore whether the activation level of microglia is consistent with maxillofacial pain level. METHODS: Chronic constriction injury of trigeminal nerve (CCI) was induced by partial ligation of infraorbital nerve (IoN) in rats. The behavioral change of rats observed at D1, D5, D10, D15, and D30 days post-surgery and the change of pain threshold were detected with electronic Von Frey filaments served as an evaluation index of maxillofacial pain. Weight change was measured by weighing. Ionized calcium binding adaptor molecule-1 (Iba-1) expression level of Sp5C at each time point was detected, and three microglia morphological categories were analyzed by immunohistochemical staining. RESULTS: The changes of behavioral and pain threshold suggested the maxillofacial pain level first increased and then decreased post-surgery in the IoN-CCI group. Both the expressions of Iba-1 and proportion of ameboid morphology in ipsilateral Sp5C increased from D1 and reached their peaks in D10 and D5, respectively. Then, they recovered nearly to the same level with contralateral Sp5C on D30. This trend was consistent with the maxillofacial change. CONCLUSIONS: The model of trigeminal neuralgia in rats constructed by partial ligation of infraorbital nerve can induce the activation of microglia in Sp5C, and the activation level is consistent with maxillofacial pain, which reached its peak at around D10 post-surgery.

NGF-Induced Upregulation of CGRP in Orofacial Pain Induced by Tooth Movement Is Dependent on Atp6v0a1 and Vesicle Release.

The nerve growth factor (NGF) and calcitonin gene-related peptide (CGRP) play a crucial role in the regulation of orofacial pain. It has been demonstrated that CGRP increases orofacial pain induced by NGF. V-type proton ATPase subunit an isoform 1 (Atp6v0a1) is involved in the exocytosis pathway, especially in vesicular transport in neurons. The objective was to examine the role of Atp6v0a1 in NGF-induced upregulation of CGRP in orofacial pain induced by experimental tooth movement. Orofacial pain was elicited by ligating closed-coil springs between incisors and molars in Sprague-Dawley rats. Gene and protein expression levels were determined through real-time polymerase chain reaction, immunostaining, and fluorescence in situ hybridization. Lentivirus vectors carrying Atp6v0a1 shRNA were used to knockdown the expression of Atp6v0a1 in TG and SH-SY5Y neurons. The release of vesicles in SH-SY5Y neurons was observed by using fluorescence dye FM1-43, and the release of CGRP was detected by Enzyme-Linked Immunosorbent Assy. Orofacial pain was evaluated through the rat grimace scale. Our results revealed that intraganglionic administration of NGF and Atp6v0a1 shRNA upregulated and downregulated CGRP in trigeminal ganglia (TG) and trigeminal subnucleus caudalis (Vc), respectively, and the orofacial pain was also exacerbated and alleviated, respectively, following administration of NGF and Atp6v0a1 shRNA. Besides, intraganglionic administration of NGF simultaneously caused the downregulation of Atp6v0a1 in TG. Moreover, the release of vesicles and CGRP in SH-SY5Y neurons was interfered by NGF and Atp6v0a1 shRNA. In conclusion, in the orofacial pain induced by experimental tooth movement, NGF induced the upregulation of CGRP in TG and Vc, and this process is dependent on Atp6v0a1 and vesicle release, suggesting that they are involved in the transmission of nociceptive information in orofacial pain.

Association of Upper Lip Morphology Characteristics with Sagittal and Vertical Skeletal Patterns: A Cross Sectional Study.

BACKGROUND: Upper lip morphology is essential in diagnosis and treatment of orthodontics and orthognathic surgery. This study is aimed to evaluate the association between upper lip characteristics (ULCs) and skeletal patterns (SPs). METHODS: 2079 patients were involved and grouped by sagittal and vertical. Class I, II, and III were identified by ANB angle, while normodivergent, hyperdivergent, and hypodivergent were identified by Facial Height Index and Sum of Angles. ULCs were evaluated by superior sulcus depth, nasolabial angle, upper lip length, basic upper lip thickness, and upper lip thickness. Confounders including demography, malocclusion, upper incisors, and upper lips were adjusted by multivariate linear regression to identify the association between ULCs and SPs. Group differences were evaluated with analysis of variance and Chi-square test. RESULTS: The mean value of ULCs and prevalence of SPs were explored in the Western China population. ULCs were significantly different in various sagittal, vertical, and combined SPs. Superior sulcus depth was negatively related to Class II, and positively related to Class III and the hypodivergent pattern after adjusted by confounders. CONCLUSIONS: ULCs significantly varied among different SPs, while only superior sulcus depth was independently associated with SPs, indicating superior sulcus depth is the only ULC that might be significantly corrected by intervention of skeletal growth.

m6A regulator-mediated RNA methylation modification patterns are involved in immune microenvironment regulation of periodontitis.

The role of epigenetic regulation in immunity is emerging, especially for RNA N6-methyladenosine (m6A) modification. However, little is known about the role of m6A in the regulation of the immune microenvironment of periodontitis. Thus, we aim to investigate the impact of m6A modification in periodontitis immune microenvironment. The RNA modification patterns mediated by 23 m6A-regulators were systematically evaluated in 310 periodontitis samples. The impact of m6A modification on immune microenvironment characteristics was explored, including infiltrating immunocytes, immune reaction gene-sets and HLAs (human leukocyte antigen) gene. m6A phenotype-related immune genes were also identified. 17 m6A regulators were dysregulated and a 15-m6A regulator signature can well distinguish periodontitis and control samples. ALKBH5 and FMR1 are closely related to infiltrating monocyte abundance. ELAVL1 and CBLL1 are significant regulators in immune reaction of TNF_Family_Members_Receptors and Cytokine. The expression of HLA-B and HLA-DOA is affected by ALKBH5 and LRPPRC. 3 distinct RNA modification patterns mediated by 23 m6A regulators were identified. They differ from immunocyte abundance, immune reaction and HLA gene. 1631 m6A phenotype-related genes and 70 m6A-mediated immune genes were identified, and the biological functions of these were explored. Our finding demonstrated the m6A modification plays a crucial role in the diversity and complexity of the immune microenvironment of periodontitis.

Long non-coding RNA SLC16A1-AS1: its multiple tumorigenesis features and regulatory role in cell cycle in oral squamous cell carcinoma.

Altered expressions of long non-coding RNAs (lncRNAs) are potential cancer prognostic biomarkers that play a critical role in the development of tumorigenesis and metastasis of cancer. However, the relationship between the expression of lncRNAs in oral squamous cell carcinoma (OSCC) and the diagnosis, progression, and prognosis of OSCC has not been thoroughly elucidated. To identify the differentially expressed lncRNAs between OSCC tissue and normal tissue, RNA-Seq data were used. lncRNA SLC16A1-AS1 was significantly highly expressed in OSCC samples than that in normal samples. Systematic bioinformatics analysis revealed that SLC16A1-AS1 was associated with histological tumor grades and overall survival status, as well as copy number variation, somatic mutation, tumor mutation burden, tumor stemness, tumor microenvironment and infiltrating immune cells. According to three advanced bioinformatic algorithms prediction (WGCNA, GSEA and GSVA), SLC16A1-AS1 played an essential role in OSCC proliferation and its biological function was related to cell-cycle regulation. Loss-of-function experiments were performed to determine the biological functions of SLC16A1-AS in OSCC cells. Silencing SLC16A1-AS1 significantly reduced the cell proliferation rate and colony-forming ability in both CAL27 and SCC25 cell lines. Flow cytometry and western blot analysis revealed that SLC16A1-AS1 silencing induced G0/G1 cell cycle arrest and inhibited the expression of cyclin D1 in both CAL27 and SCC25 cells. In conclusion, our study comprehensively investigated the role of the lncRNA SLC16A1-AS1 in OSCC growth and proved that it may serve as a new diagnostic indicator and a new target for the treatment of OSCC.

Prognostic significance of X-linked inhibitor of apoptosis protein in patients with gastrointestinal tract cancers: A meta-analysis.

BACKGROUND: The aim of this meta-analysis was to systematically evaluate the prognostic significance of X-linked inhibitor of apoptosis protein (XIAP) in patients with gastrointestinal tract (GIT) cancers. METHODS: PubMed, Web of Science, EMBASE, Cochrane Library and China National Knowledge Infrastructure were searched for potentially eligible literature. The baseline characteristics and relevant data were extracted. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated to assess the prognostic role of XIAP in patients with GIT cancers. RESULTS: Twelve studies with 2,477 patients were included. The pooled HRs of higher expression of XIAP for overall survival (OS) and recurrence free survival (RFS) in patients with GIT cancers were 1.64 (95% CI, 1.27-2.13) and 1.06 (95% CI, 0.96-1.16), respectively. Subgroup analysis and sensitivity analysis were also performed. No significant publication bias was found. CONCLUSION: Our results suggested that XIAP could be a prognostic marker for OS but not RFS in patients with GIT cancers. Higher expression of XIAP was related to poorer OS. These findings may help evaluate the prognosis of patients and assist future research on novel therapeutic strategies of GIT cancers by targeting XIAP. However, more well-designed studies are warranted to verify the results.

Efficacy of Probiotics as Adjunctive Therapy to Nonsurgical Treatment of Peri-Implant Mucositis: A Systematic Review and Meta-Analysis.

Background: Peri-implant mucositis (PiM) is an inflammation of the soft tissues surrounding the dental implant and is the precursor of the destructive inflammatory peri-implantitis. PiM is usually reversible, but difficult to eradicate. Mechanical debridement (MD) is the conventional procedure to treat PiM although not enough to reach a complete resolution. Recently, probiotics have been considered in the treatment of peri-implant disease. Therefore, the aim of this systematic review and meta-analysis was to investigate the efficacy of the probiotic therapy combined with MD compared with MD alone or MD + placebo in patients with PiM. Methods: A search using electronic databases (MEDLINE, Science Direct databases, and Cochrane Central Register of Controlled Trials) and a manual search were performed up to November 2019 by two reviewers independently of each other. Eligible randomized controlled trials (RCTs) comparing MD + probiotic vs. MD were included. The quality assessment for all the selected RCTs was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions. Probing depth reduction was selected as the primary outcome. Weighted mean difference (WMD) and 95% confidence interval (CI) were calculated for continuous outcomes, and odds ratio (OR) and 95% CI were calculated for dichotomous outcomes, using random effect models. This review was registered on the PROSPERO database (CRD42020213625). Results: Five eligible publications were included in this systematic review and four in the meta-analysis. As regards the implant, the WMD in the probing depth reduction between the test and control group was -0.12 mm [95% CI (-0.38, 0.14), p = 0.38], meaning that the adjunctive probiotic therapy was not improving PiM compared with MD alone or MD + placebo. The meta-analysis also showed no statistically significant results in the secondary outcomes (reduction of full mouth plaque index and full mouth bleeding on probing, absence of bleeding on probing at implant level, and changes in microorganism load and species). Conclusion: The findings of this systematic review and meta-analysis suggested that the additional use of probiotics did not improve the efficacy of MD in PiM treatment regarding clinical and microbial outcomes, at least in a short-term.

RALBP1 regulates oral cancer cells via Akt and is a novel target of miR-148a-3p and miR-148b-3p.

BACKGROUND: Malignant tumors arising from the epithelium of the oral cavity are termed as squamous cell carcinomas (OSCC). The aim of the current work was to understand the role of an isoform of RAS-like protein (RAL), RALBP1, in mediating squamous cell tumorigenesis. The study also aims to understand epigenetic modifications of RALBP1 mediated through microRNA-148a/b-3p. METHODS: Biopsies of tumor and healthy tissues from 25 patients with OSCC were collected and subjected to RNA and protein extraction to confirm upregulation of RLBP1 in tumor tissues. Expression of RLBP1 was silenced in SCC-9, using shRNA, and HN6 was transfected with plasmid bearing genes for RLBP1 over expression. Tumorigenic traits such as increased glucose uptake, aerobic glycolysis, enhanced cellular survival, cell migration, and invasion were assessed. Probable, molecular machinery involved in the upregulation was also assessed using Western blots. Using Target Scan tool, the miRNAs targeting RLBP1 were identified. Rescue of phenotypes in presence of miRNAs were also evaluated. RESULTS: Over expression of RLBP1 was associated with increased glucose uptake and aerobic glycolysis mediated ATP synthesis. The cells divided at a faster rate with a higher rate of migration and invasion phenotype. miR-148a/b-3p were found to target RLBP1 and rescued RLBP1 mediated phenotype. CONCLUSION: RLBP1 may mediate squamous cell tumorigenesis in oral cavity, independently of the RAS protein and through Akt. miR-148a/b-3p functions as a tumor suppressor by targeting RLBP1.

The effect of capsaicin on expression patterns of CGRP in trigeminal ganglion and trigeminal nucleus caudalis following experimental tooth movement in rats

ABSTRACT Objectives The aim of this study was to explore the effect of capsaicin on expression patterns of calcitonin gene-related peptide (CGRP) in the trigeminal ganglion (TG) and trigeminal subnucleus caudalis (Vc) following experimental tooth movement. Material and Methods Male Sprague-Dawley rats were used in this study and divided into small-dose capsaicin+force group, large-dose capsaicin+force group, saline+force group, and no force group. Closed coil springs were used to mimic orthodontic forces in all groups except for the no force group, in which springs were inactivated. Capsaicin and saline were injected into periodontal tissues. Rats were euthanized at 0 h, 12 h, 1 d, 3 d, 5 d, and 7 d following experimental tooth movement. Then, TG and Vc were obtained for immunohistochemical staining and western blotting against CGRP. Results Immunohistochemical results indicated that CGRP positive neurons were located in the TG, and CGRP immunoreactive fibers were distributed in the Vc. Immunohistochemical semiquantitative analysis and western blotting analysis demonstrated that CGRP expression levels both in TG and Vc were elevated at 12 h, 1 d, 3 d, 5 d, and 7 d in the saline + force group. However, both small-dose and large-dose capsaicin could decrease CGRP expression in TG and Vc at 1 d and 3 d following experimental tooth movement, as compared with the saline + force group. Conclusions These results suggest that capsaicin could regulate CGRP expression in TG and Vc following experimental tooth movement in rats.

The Accuracy of Computer Image-Guided Template for Mandibular Angle Ostectomy.

BACKGROUND: Mandibular angle ostectomy (MAO) is commonly used to correct prominent mandibular angles through an intraoral approach. However, limited vision in the operative site may lead to difficulties or complications during surgery. Therefore, it is necessary to develop an effective method for helping surgeons to perform MAO more precisely and safely. METHODS: In this study, we report a novel method of a computer image-guided surgical template for navigation of MAO, and evaluate its accuracy and clinical outcomes. Nine patients with a prominent mandibular angle were enrolled in this study. A pair of stereolithographic templates was fabricated by computer-aided image design and 3D printing. In all cases, bilateral MAO was performed under the guide of these templates. Post-operative effects were evaluated by 3D curve functions and maximal shell-to-shell deviations. RESULTS: All patients were satisfied with their cosmetic outcomes. The mean and SD of ICC between R-Sim and R-Post were 0.958 ± 0.011; between L-Sim and L-Post, 0.965 ± 0.014; and between R-Post and L-Post, 0.964 ± 0.013. The maximal shell-to-shell deviations between the simulated mandibular contour and post-operative mandibular contour on the right and left sides were 2.02 ± 0.32 and 1.97 ± 0.41 mm, respectively. CONCLUSION: The results of this study suggest that this new technique could assist surgeons in making better pre-surgical plans and ensure more accurate and safer manipulation for completion of this procedure.

The effectiveness of low-level laser therapy in accelerating orthodontic tooth movement: a meta-analysis.

Low-level laser therapy is claimed to accelerate bone remodeling. The aim of this meta-analysis was to critically appraise current evidence and to determine the effectiveness of low-level laser therapy in accelerating orthodontic tooth movement. PubMed, Web of Knowledge, Embase, CENTRAL, ProQuest Dissertations &Theses, and SIGLE were electronically searched from Jan 1990 to Jun 2013. Article screening, data extraction, assessment of risk of bias and evaluation of evidence quality through GRADE were conducted independently and in duplicate by two reviewer authors. Outcome of interest in this meta-analysis was accumulative moved distance (AMD). Meta-analyses were performed in Comprehensive Meta-Analysis Version 2.2.064 (Biostat, Englewood, NJ, USA). Finally, five studies were included in this meta-analysis. The meta-analysis revealed that the pooled difference in mean (DM) was 0.33 [95 % CI: (0.03-0.64)], 0.76 [95 % CI: (-0.14, 1.65)] and 0.43 [95 % CI: (-0.05, 0.91)] for AMD within 1 month, AMD within 2 months and AMD within 3 months, respectively. However, significant heterogeneities and instability of the pooled results were detected. Moreover, publication bias was found for AMD within 3 months. The subgroup analysis on the wavelength of 780 nm revealed that the pooled DM of AMD were 0.54 (95 % CI = 0.18-0.91), 1.11 (95 % CI = 0.91-1.31) and 1.25 (95 % CI = 0.68-1.82) for 1, 2, and 3 months, respectively. For the output power of 20 mW, the subgroup analysis showed that the pooled DM of AMD was 0.45 (95 % CI = 0.26-0.64), 1.11 (95 % CI = 0.91-1.31), and 1.25 (95 % CI = 0.68-1.82) for 1, 2, and 3 months, respectively. Weak evidence suggests that low-level laser irradiations at the wavelength of 780 nm, at the fluence of 5 J/cm(2) and/or the output power of 20 mW could accelerate orthodontic tooth movement within 2 months and 3 months. However, we cannot determine its effectiveness within 1 month due to potential measurement errors.

Integration accuracy of laser-scanned dental models into maxillofacial cone beam computed tomography images of different voxel sizes with different segmentation threshold settings.

OBJECTIVE: The aims were to examine the influence of cone beam computed tomography (CBCT)-scanned voxels and segmentation threshold settings on the accuracy of surface-based registration. STUDY DESIGN: The samples were obtained from 10 adults. Each laser-scanned model was registered into a CBCT model by use of the iterative closest point algorithm. We calculated the shell-to-shell deviations between the 2 models and evaluated the results with color-mapping methods. The centroid coordinates were used to calculate the positional differences. Thresholds were expressed in relative Hounsfield units (RHU). RESULTS: There was a statistically significant difference in shell-to-shell deviations between the 0.20-mm-voxel group and the 0.40-mm-voxel group (P < .001). There was a statistically significant difference in anteroposterior and superoinferior directions between the 200- and 700-RHU threshold models in 2 groups (P < .05). CONCLUSIONS: The results indicated that the accuracy of the integration of laser-scanned dental models into CBCT images is higher with a high-RHU threshold setting in 0.20- and 0.40-mm voxel sizes.

Finite element analysis of rapid canine retraction through reducing resistance and distraction

Objective: The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis. Material and Methods: Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises) stress and maximum shear stress. Results: The maximum value of total deformation with the three kinds of models occurred in the distal part of the canine crown and gradually reduced from the crown to the apex of the canine; compared with the canines in model 3 and model 1, the canine in model 2 had the maximum value of displacement, up to 1.9812 mm. The lowest equivalent (von Mises) stress and the lowest maximum shear stress were concentrated mainly on the distal side of the canine root in model 2. The distribution of equivalent (von Mises) stress and maximum shear stress on the PDL of the canine in the three models was highly concentrated on the distal edge of the canine cervix. . Conclusions: Removal of the bone in the pathway of canine retraction results in low stress intensity for canine movement. Periodontal distraction aided by surgical undermining of the interseptal bone would reduce resistance and effectively accelerate the speed of canine retraction. .

PAX9 polymorphism and susceptibility to sporadic non-syndromic severe anodontia: a case-control study in southwest China

Our research aimed to look into the clinical traits and genetic mutations in sporadic non-syndromic anodontia and to gain insight into the role of mutations of PAX9, MSX1, AXIN2 and EDA in anodontia phenotypes, especially for the PAX9. Material and Methods The female proband and her family members from the ethnic Han families underwent complete oral examinations and received a retrospective review. Venous blood samples were obtained to screen variants in the PAX9, MSX1, AXIN2, and EDA genes. A case-control study was performed on 50 subjects with sporadic tooth agenesis (cases) and 100 healthy controls, which genotyped a PAX9 gene polymorphism (rs4904210). Results Intra-oral and panoramic radiographs revealed that the female proband had anodontia denoted by the complete absence of teeth in both the primary and secondary dentitions, while all her family members maintained normal dentitions. Detected in the female proband were variants of the PAX9 and AXIN2 including A240P (rs4904210) of the PAX9, c.148C>T (rs2240308), c.1365A>G (rs9915936) and c.1386C>T (rs1133683) of the AXIN2. The same variants were present in her unaffected younger brother. The PAX9 variations were in a different state in her parents. Mutations in the MSX1 and EDA genes were not identified. No significant diferences were found in the allele and genotype frequencies of the PAX9 polymorphism between the controls and the subjects with sporadic tooth agenesis. Conclusions These results suggest that the association of A240P with sporadic tooth agenesis still remains obscure, especially for different populations. The genotype/phenotype correlation in congenital anodontia should be verified. .

[Cleidocranial dysplasia: a case report].

A case of cleidocranial dysplasia (CCD) was reported and relevant literatures were reviewed. The diagnosis and treatment of this case were discussed.

Behavioural responses and expression of P2X3 receptor in trigeminal ganglion after experimental tooth movement in rats.

OBJECTIVE: To explore the role of P2X(3) receptor in pain induced by experimental tooth movement. DESIGN: Male Sprague-Dawley rats weighing 200-300g were used. P2X(3) receptor distribution in the caudal one-third portion of the trigeminal ganglion (TG) was studied by IHC. Next, the changes of P2X(3) expression were detected by Western blotting 4h, 1d, 2d, 3d, 5d, 7d, 14d after tooth movement. We then developed a behaviour pain model associated with directed mouth wiping. Finally, the effect of TNP-ATP on nociceptive-like behaviour was evaluated. RESULTS: Our results showed that P2X(3) receptors were expressed mainly in small- and medium-sized cells and experimental tooth movement led to an increase in staining of mandibular P2X(3) receptors. In addition, following experimental tooth movement, the expression of P2X(3) receptor in TG was statistically significantly up-regulated from days 1 to 5, with a peak on day 3. It was also found that the time spent on directed mouth wiping was dramatically increased by experimental tooth movement from days 1 to 7. The rhythm change of P2X(3) receptor expression in TG and the mouth wiping behaviour were in concert with the initial orthodontic pain responses. The directed mouth wiping behaviour was modulated in a force-dependent manner and could be attenuated by peripheral and systemic morphine. Furthermore, peripherally administered TNP-ATP could exert an analgesic effect on this pain model. CONCLUSION: These results suggest that directed mouth wiping behaviour can be a reliable measurement of pain following experimental tooth movement in rats. The P2X(3) receptor is important in the development and maintenance of tooth movement pain and thus may be peripheral targets for analgesics in orthodontic pain control.