Acute pulpitis promotes purinergic signaling to induce pain in rats via P38MAPK/NF-κB signaling pathway.

Toothache is one of the most common types of pain, but the mechanisms underlying pulpitis-induced pain remain unknown. The ionotropic purinergic receptor family (P2X) is reported to mediate nociception in the nervous system. This study aims to investigate the involvement of P2X3 in the sensitisation of the trigeminal ganglion (TG) and the inflammation caused by acute pulpitis. An acute tooth inflammation model was established by applying LPS to the pulp of SD rats. We found that the increased expression of P2X3 was induced by acute pulpitis. A selective P2X3 inhibitor (A-317491) reduced pain-like behavior in the maxillofacial region of rats and depressed the activation of neurons in the trigeminal ganglion induced by pulpitis. The upregulated MAPK signaling (p-p38, p-ERK1/2) expression in the ipsilateral TG induced by pulpitis could also be depressed by the application of the P2X3 inhibitor. Furthermore, the expression of markers of inflammatory processes, such as NF-κB, TNF-α and IL-1ß, could be induced by acute pulpitis and deduced by the intraperitoneal injection of P2X3 antagonists. Our findings demonstrate that purinergic P2X3 receptor signaling in TG neurons contributes to pulpitis-induced pain in rats and that P2X3 signaling may be a potential therapeutic target for tooth pain.

Leptin induces IL-6 and IL-8 expression through leptin receptor Ob-Rb in human dental pulp fibroblasts.

OBJECTIVE: Leptin, through binding to its special receptor (Ob-Rb), has potent effects on immunity and inflammation. This study aimed to investigate the expression of leptin receptor Ob-Rb in human dental pulp fibroblasts (HDPFs) and the effects of leptin on the production of proinflammatory cytokines of IL-6 and IL-8 by HDPFs. METHODS: Ob-Rb expression was determined by quantitative real-time PCR (real-time PCR), Western blot and immunofluorescence analyses in cultured HDPFs. Small interfering RNA (siRNA) was transfected into HDPFs to down-regulate the expression of Ob-Rb. Real-time PCR and enzyme-linked immunosorbent assay (ELISA) were used to determine the proinflammatory cytokines of IL-6 and IL-8 levels in leptin-stimulated HDPFs. The involved signalling pathways that mediate the leptin-stimulated production of proinflammatory cytokines were investigated using Western blot and specific signalling inhibitor analyses. RESULTS: The expression levels of Ob-Rb mRNA and protein were detected in HDPFs. Leptin could stimulate mRNA and protein expression of IL-6 and IL-8 in HDPFs in a concentration-dependent and time-dependent manner. Transfection with siRNA targeting Ob-Rb resulted in remarkable reduction of IL-6 and IL-8 expressions by HDPFs. In accordance with the enhanced expression of proinflammatory cytokines, leptin stimulation resulted in rapid phosphorylation of STAT3, p38 MAPK, ERK and Akt in HDPFs. Inhibiting JAK2/STAT3, p38 MAPK or PI3K/Akt substantially decreased leptin-induced IL-6 production, whereas blocking ERK and p38 MAPK substantially suppressed IL-8 production from leptin-stimulated HDPFs. CONCLUSIONS: Leptin may up-regulate IL-6 and IL-8 production through binding with Ob-Rb in HDPFs via the activation of different intracellular signalling pathways.

Effect of visual method vs plaque disclosure in enhancing oral hygiene in adolescents and young adults: a single-blind randomized controlled trial.

INTRODUCTION: Enamel demineralization and gingival inflammation are the most prevalent consequences of biofilm formation in orthodontics. Our hypothesis was that educating patients about the severe consequences of biofilm accumulation could enhance their oral hygiene while wearing fixed appliances. METHODS: This study was designed as a randomized controlled 4-arm parallel trial. A total of 148 participants in Chengdu, China, matching the eligibility criteria of 11 to 25 years of age, at least 20 natural teeth, and a treatment plan that included conventional stainless steel brackets, were randomly assigned to 4 intervention groups based on computer-generated random sequencing using simple randomization without blocking. In group A (n = 37), the subjects were shown images illustrating the severe consequences of biofilm formation, including enamel demineralization and gingival inflammation; subjects in group B (n = 40) were given biofilm disclosing tablets; those in group C (n = 38) received a combination of A and B; the subjects in group D (n = 33) served as the controls. The investigators were blinded to the allocations, and the researcher managing the random sequence did not participate in allocation or measurement. All groups received routine oral hygiene instructions. Plaque index and gingival index scores were recorded at each appointment during a 6-month follow-up. RESULTS: Eighteen participants were lost during follow-up, resulting in a total of 130 participants after the trial (group A, 35; group B, 32; group C, 34; group D, 29). No adverse events were recorded. Groups A and C exhibited a significantly lower plaque index scores (parameter-estimate [95% confidence interval] = -1.20 [-1.76 to -0.63] for group A, and -1.12 [-1.69 to -0.56] for group C) and gingival index scores (-0.13 [-0.21 to -0.04], and -0.19 [-0.28 to -0.10]), respectively, compared with group D (P <0.001 for all), whereas no significant difference was found between groups B and D, or between groups A and C (P >0.05). The adults had significantly lower plaque index (0.48 [0.13-0.84], P <0.001) and gingival index (0.06 [0.01-0.11], P = 0.018) scores than did the teenagers, and the female subjects had significantly higher gingival index (-0.06 [-0.11 to -0.01], P = 0.040) scores than did the male subjects. CONCLUSIONS: The use of images showing the severe consequences of biofilm accumulation enhanced the oral hygiene of patients treated with fixed appliances.

The purinergic receptor P2X3 promotes facial pain by activating neurons and cytokines in the trigeminal ganglion.

The mechanism underlying allodynia/hyperalgesia caused by dental pulpitis has remained enigmatic. This investigation endeavored to characterize the influence of the purinergic receptor P2X3 on pain caused by experimental pulpitis and the mechanism involved. An experimental model of irreversible pulpitis was produced by the drilling and exposure of the dental pulp of the left upper first and second molars in rats, followed by measuring nociceptive responses in the oral and maxillofacial regions. Subsequently, neuronal activity and the expression of P2X3 and pertinent cytokines in the trigeminal ganglion (TG) were meticulously examined and analyzed. Histological evidence corroborated that significant pulpitis was produced in this model, which led to a distinct escalation in nociceptive responses in rats. The activation of neurons, coupled with the upregulated expression of c-fos, P2X3, p-p38, TNF-α and IL-1ß, was identified subsequent to the pulpitis surgery within the TG. The selective inhibition of P2X3 with A-317491 effectively restrained the abnormal allodynia/hyperalgesia following the pulpitis surgery and concurrently inhibited the upregulation of p-p38, TNF-α and IL-1ß within the TG. These findings suggest that the P2X3 signaling pathway plays a pivotal role in instigating and perpetuating pain subsequent to the induction of pulpitis in rats, implicating its association with the p38 MAPK signaling pathway and inflammatory factors.

Autophagy appears during the development of the mouse lower first molar.

Odontogenesis consists of a series of consecutive tooth morphogenesis stages, in which apoptosis is involved to eliminate the unnecessary cells. Autophagy, a lysosome or endosome-mediated self-degradation process, is indicated to participate in embryogenesis and tissue morphogenesis associated with apoptosis. This study hypothesized that autophagy may be involved and associated with apoptosis in odontogenesis. The transcripts of autophagy-related genes (Atg5, Atg7, and Atg12) were positively detected in tooth germs at embryonic day (E) 14.5 and postnatal day (P) 5.5 by quantitative real-time PCR. The protein expression of Atg5-Atg12 conjugate and lipidation of LC3 (microtubule-associated protein 1 light chain 3, autophagic marker) were revealed in the developing tooth germs by western blot. Meanwhile, LC3 was immunolocalized in the enamel organ and dental papilla at embryonic stages (E13.5-E18.5), especially stage E14.5 cervical loop and the PEK that facing the mesenchyme. At postnatal stages (P1.5-P15.5), besides the dental epithelium cells, LC3 was detected in the differentiating and differentiated odontoblasts, dental follicle cells, and Hertwig's epithelium root sheath cells. Moreover, double-immunofluorescence analysis revealed the partial colocalization of LC3 and TUNEL signal in the E14.5 PEK that facing the mesenchyme, the E16.5 stratum intermedium and outer enamel epithelium, the P5.5 stratum intermedium and stellate reticulum. Nevertheless, LC3 was also found in non-apoptotic cells. Furthermore, the transmission electron microscopic images revealed the presence of autophagy, as well as the partial colocalization of autophagic vacuoles and apoptotic nuclei during tooth development. Our findings imply the developmental appearance of autophagy and its partial colocalization with apoptosis during odontogenesis.

Extracellular vesicles secreted by human periodontal ligament induced osteoclast differentiation by transporting miR-28 to osteoclast precursor cells and further promoted orthodontic tooth movement.

BACKGROUND: Osteoclast differentiation plays a key role in orthodontic tooth movement (OTM). We aimed to explore the role of human periodontal ligament (hPDL) extracellular vesicles (EVs) in osteoclast differentiation and OTM. METHODS: The hPDL cells were exposed to 4.0 g/cm2 compression force (CF) and the hPDL-EVs were collected. The peripheral blood mononuclear cells were isolated, purified, and induced osteoclast differentiation. The OTM rat model was established through excess orthodontic force. Dual-luciferase reporter gene assay verified the targeting effect of miR-28 on RUNX1. In addition, tartrate-resistant acid phosphase (TRAP) staining, immunofluorescence, western blot, and quantitative real-time PCR were also carried out. RESULTS: CF pretreated hPDL-EVs promoted osteoclast differentiation and down-regulated RUNX1 levels in in vitro and in vivo experiments. The addition of CF-hPDL-EVs also elevated tooth movement in OTM rats. Besides, miR-28 was significantly up-regulated in CF-pretreated hPDL-EVs. In addition, RUNX1 was negatively regulated by miR-28. Moreover, the addition of CF-lenti-miR-28 inhibitor-Evs down-regulated the expression of osteoclast marker genes and the number of TRAP positive (+) multinucleated cells (MNCs) in vitro. Furthermore, in vivo experiments confirmed that CF-lenti-miR-28 inhibitor-Evs injection down-regulated the number of TRAP (+) MNCs and inhibited tooth movement of OTM rats. CONCLUSION: CF-treated hPDL-EVs promoted osteoclast differentiation by transporting miR-28 and inhibiting the expression of RUNX1, which provides new insight into the specific mechanism of hPDL-Evs affecting osteoclast differentiation.

Healing of acute alveolar bone dehiscence following treatment with porous biphasic calcium phosphate in beagle dogs.

The purpose of the present study was to evaluate histologically in beagle dogs the healing in acute dehiscence type defects following treatment with open flap debridement (OFD) with or without porous biphasic calcium phosphate (PBCP). Alveolar bone dehiscence defects were surgically created bilaterally at the labial aspects of maxillary third incisors in 12 beagle dogs. After root conditioning with ethylenediaminetetraacetate, PBCP was filled in the defects and the contralaterals were cured with OFD. Two fluorochrome labelings were administered at the 7th and 11th weeks, respectively. Four dogs were killed at the 12, 16, and 24 weeks, respectively. Histological observations were processed through microcomputed tomographic imaging, fluorescence microscope, and light microscopy. The formation of new regenerated tissues was assessed histomorphometrically. The results revealed the healing after treatments with PBCP evidenced a new attachment apparatus and that with OFD supported periodontal repair. In PBCP groups, the amount of new bone varied from 1.15 to 3.86 mm (23-77.2% of the original defect size), while only 0.3 to 1.04 mm (6-20.8%) in OFD group. The amount of new cementum in PBCP varied from 1.18 to 4.16 mm (23.6-82.3%), while only 0.67 to 1.15 mm (13.4-23%) in OFD group. The amount of periodontal ligament in PBCP varied from 1.03 to 4.12 mm (20.6-82.4%), while only 0 to 0.93 mm (0-18.6%) in OFD group. There was significantly more regenerated tissue in PBCP groups compared to OFD procedures (p < 0.01). The present results indicate that PBCP may enhance periodontal regeneration in acute-type labial dehiscence defects.

Runx1/miR-26a/Jagged1 signaling axis controls osteoclastogenesis and alleviates orthodontically induced inflammatory root resorption.

BACKGROUND: MicroRNAs (miRNAs) are involved in the regulation of osteoclast biology and several pathogenic progression. This study aimed to identify the role of miR-26a in osteoclastogenesis and orthodontically induced inflammatory root resorption(OIIRR). METHODS: Rat orthodontic tooth movement (OTM) model was established by ligating a closed coil spring between maxillary first molar and incisor, and 50 g orthodontic force was applied to move upper first molar to middle for 7 days. Human periodontal ligament (hPDL) cells were isolated from periodontium of healthy donors, and then subjected to compression force (CF) for 24 h to mimic an in vitro OTM model. The levels of associated factors in vivo and in vitro were measured subsequently. RESULT: The distance of tooth movement was increased and root resorption pits were occurred in rat OTM model. The expression of miR-26a was decreased in vivo and vitro experiments. CF treatment enhanced the secretion of inflammatory factors receptor activator of nuclear factor-kappa B ligand (RANKL) and IL-6, osteoclast marker levels, and the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts, while miR-26a overexpression reversed these results. Furthermore, miR-26a overexpression inhibited the osteoclastogenesis and rescued the root resorption in OTM rats through inhibition of Jagged1. Additionally, Runx1 could bind to miR-26a promoter and promote its expression, thereby suppressing the osteoclastogenesis. CONCLUSION: We concluded that Runx1/miR-26a/Jagged1 signaling axis restrained osteoclastogenesis and alleviated OIIRR.

Proteomic analysis of early-response to mechanical stress in neonatal rat mandibular condylar chondrocytes.

The objectives of this study were to investigate the early response to mechanical stress in neonatal rat mandibular chondrocytes by proteomic analysis. To evaluate its molecular mechanism, chondrocytes were isolated and cultured in vitro, then loaded mechanical stress by four-point bending system on different patterns. Morphological observation, flow cytometric analysis, and MTT assays indicated that 4,000 microstrain loading for 60 min was an appropriate mechanical stimulus for the following proteome analysis, which produced a transient but obvious inhibitory effect on the cell cycle. Therefore, we took a proteomic approach to identify significantly differential expression proteins in chondrocytes under this mechanical stress. Using 2-DE and MALDI-TOF, we identified seven differentially expressed proteins including the MAPK pathway inhibitor RKIP, cytoskeleton proteins, actin and vimentin, and other selected proteins. Some differentially expressed proteins were validated by both Western blot analysis and fluorescent staining of cytoskeleton at different loading times. The vimentin and RKIP responsive expression were also proven in vivo in oral orthopedic treatment rats, which was in line with the result in vitro. The histological changes in cartilage also showed the inhibition effect. Furthermore, the expressional level of phosphorylated ERK was increased, which demonstrates the changes in MAPK activity. Taken together, these data indicate that mechanical stress resulted in vimentin expression changes first and then led to the subsequent changes in actin expression, MAPK pathway regulated by RKIP and heat shock protein GRP75. All those changes contributed to the cytoskeleton remolding and cell cycle inhibition, finally led to condylar remodeling.

Oral bacterial adhesion forces to biomaterial surfaces constituting the bracket-adhesive-enamel junction in orthodontic treatment.

Bacterial adhesion to biomaterial surfaces constituting the bracket-adhesive-enamel junction represents a growing problem in orthodontics, because bacteria can adversely affect treatment by causing demineralization of the enamel surface around the brackets. It is important to know the forces with which bacteria adhere to the surfaces of these junction materials, as the strength of these forces will determine how easy it will be to remove the bacteria. We compared the adhesion forces of five initially colonizing and four cariogenic strains of bacteria to an orthodontic adhesive, stainless steel, and enamel, with and without a salivary conditioning film. Adhesion forces were determined using atomic force microscopy and a bacterial probe. In the absence of a salivary conditioning film, the strongest bacterial adhesion forces occurred to the adhesive surface (-2.9 to -6.9 nN), while adhesion forces to the enamel surfaces were lowest (-0.8 to -2.7 nN). In the presence of a salivary conditioning film, adhesion forces were reduced strongly, to less than 1 nN, and the differences between the various materials were reduced. Generally, however, initial colonizers of dental hard surfaces presented stronger adhesion forces to the different materials (-4.7 and -0.6 nN in the absence and presence of a salivary conditioning film, respectively) than cariogenic strains (-1.8 and -0.5 nN).

Biologic response of rapid tooth movement with periodontal ligament distraction.

INTRODUCTION: Length of treatment is a complaint of many orthodontic patients. The purpose of this study was to evaluate the security and feasibility of rapid tooth movement with periodontal ligament distraction. METHODS: Eight male beagles, aged 13 to 16 months, were used in this study. Extraction of the mandibular second premolar and alveolar surgery to reduce the osteal resistance on the mesial side of the extraction socket were performed on the experimental side. Then a device was placed to distract the first premolars distally on the experimental side; on the control side, the first premolars were distalized with nickel-titanium coil springs. The beagles were killed in the first, second, fourth, and eighth weeks after orthodontic force application. RESULTS: The first premolar on the experimental side moved more rapidly than that on the control side (P <0.05). Histologic data indicated that more new bone was deposited on tension area of the experimental side than on the control side. Active and extensive bone resorption in the compressive area and bone deposition in the tension area were observed on the experimental side. CONCLUSIONS: These results suggest that the periodontal ligament can be rapidly distracted without complications. The rapid orthodontic tooth movement by distracting the periodontal ligament cannot be emulated by current conventional orthodontic concepts and methods.

Regulation of the response of the adult rat condyle to intermaxillary asymmetric force by the RANKL-OPG system.

OBJECTIVE: To test the hypothesis that the RANKL-OPG system in the subchondral bone of adult rat condyles does not vary in response to different values of intermaxillary asymmetrical forces. MATERIALS AND METHODS: The mandibular rami of 160 Sprague-Dawley rats (3 months old) were subjected to unilateral traction in the anterior-superior direction using an elastic force. We used 120 g and 40 g as the initial elastic forces, and then removed the traction after 28 days. The expression of RANKL and OPG in the subchondral bone of the condyles was analyzed by semiquantitative immunohistochemistry. RESULTS: Different force levels induced similar changes in the expression of the OPG protein by 28 days. However, the effect of a 120-g elastic force on the expression of RANKL was stronger than that of a 40-g force. Because of the asynchrony of RANKL responses to external forces of different values, the values of RANKL/OPG ratio showed characteristic variation. The RANKL/ OPG ratio in the side treated with heavy force showed a distinct negative correlation with the value obtained when a light force was used. CONCLUSIONS: The hypothesis is rejected. Different values or traction force cause a variation of the RANKL/OPG ratio through the expression of RANKL protein, modulating the activities of bone remodeling in the subchondral bone of condyle.

Knockdown of DANCR reduces osteoclastogenesis and root resorption induced by compression force via Jagged1.

LncRNA DANCR has been proven to be involved in osteoblast differentiation. This study aims to investigate the role of DANCR in osteoclast formation and root resorption in periodontal ligament (PDL) cells induced by compression force (CF). Rat orthodontic tooth movement (OTM) model was established. The molecules expressions in the areas of root resorption form OTM model were measured. The number of osteoclasts was measured using Tartrate-resistant acid phosphatase (TRAP) staining. The bone resorption was detected using pit formation assay. We showed that the expression of DANCR and Jagged1 protein was increased in rat OTM model and human periodontal ligament (hPDL) cells treated with CF, and CF increased the production of Jagged1, RANKL, and IL-6 from the hPDL cells. Moreover, DANCR could positively regulate Jagged1 protein expression. Knockdown of DANCR could change the promotion effect of CF on osteoclastogenesis and bone resorption in vitro and in vivo experiments, while overexpression of Jagged1 reversed si-DANCR effect. Taken together, knockdown of DANCR reduced osteoclast formation and root resorption induced by CF via Jagged1.

Effects of Class III magnetic orthopedic forces on the craniofacial sutures of rhesus monkeys.

INTRODUCTION: The objectives of this study were to develop an intraoral intermaxillary Class III magnetic orthopedic appliance (MOA-III), to investigate the influence of Class III orthopedic forces on the craniofacial sutures of rhesus monkeys, and to elucidate the mechanism of Class III malocclusion orthopedic treatment. METHODS: Six male rhesus monkeys in the mixed-dentition stage were divided into 3 groups of 2 each: a 90-day experimental group, a 45-day experimental group, and a control group. Six craniofacial sutures were observed. The experimental monkeys received heavy forces (300 g) per side initially, created by opposing Nd(2)Fe(14)B magnetic units in a cast MOA-III. The control groups received no treatment. Before the appliances were inserted, metal implants were placed in each animal as bone markers for direct measurement. To determine the rate of bone apposition, each animal was injected with fluorescent dyes intravenously before and during the experimental period. Intraoral photographs, dental casts, and cephalometric radiographs of each animal were obtained at the beginning and end of the experiment. RESULTS: Distances between metal implants on both sides of the sutures were enlarged in the experimental groups. Cephalometric analysis showed that the treatment effects of MOA-III are a combination of skeletal and dental changes in the maxilla and the mandible. Distinct changes from physiologic growth remodeling were observed in some sutures but not in the control groups. No inflammation was noted in either experimental or control monkeys. CONCLUSIONS: The MOA-III can be an efficient intraoral appliance to treat Class III malocclusion that is caused by a deficient maxilla; heavy orthopedic forces (300 g per side) are safe and effective in the rhesus monkey.

[PAR index of adolescents with congenital missing teeth pre- and post-orthodontic treatment].

OBJECTIVE: To assess the outcome of orthodontic treatment for adolescents with congenital missing teeth using the PAR (Peer Assessment Ration) index. METHODS: The PAR index was adopted to evaluate and compare the teeth arrangement, molar occlusion, overjet, overbite and centerline condition of 20 adolescents with congenital missing teeth before and after orthodontic treatments. RESULTS: The initial PAR scores and weighted PAR total scores decreased significantly after Orthodontic treatments (P < 0.01), except for the centerline. The PAR total scores decreased by 14.25 +/- 7.91 (80.90% +/- 11.09%). The weighted PAR total scores decreased by 15.45 +/- 8.16 (75.34% +/- 18.41%). CONCLUSION: PAR index can well reflect the improvement of occlusion characters by orthodontic treatment for adolescents with congenital missing teeth. But further improvement is needed for clinical application.

Rapid orthodontic tooth movement aided by alveolar surgery in beagles.

INTRODUCTION: It has been reported that oral surgery can accelerate orthodontic tooth movement. The purpose of this study was to evaluate the effects of alveolar surgery that undermines interseptal bone in orthodontic tooth movement. METHODS: Ten male beagles, aged 12 to 15 months, were used in this study. Extraction of the mandibular second premolar and alveolar surgery to reduce the osteal resistance on the mesial side of the extraction socket were performed on the experimental side; on the control side, only the second premolar was extracted. The first premolars were distalized against the third premolars with orthodontic nickel-titanium coil springs on the both sides. The beagles were killed in the first, second, third, fourth, and eighth weeks after orthodontic force application. RESULTS: The first premolar on the experimental side moved more rapidly than that on the control side (P <.01). Tissue slices were obtained for histological evaluation. No obvious root resorption and no irreversible injury to the pulp were observed on either side. Active and extensive bone resorption in the compressive area and bone deposition in the tension area were observed on the experimental sides. CONCLUSIONS: Self-fluorescence checks showed that more new bone was deposited in the tension area of the experimental side than on the control side (P <.05). These results suggest that alveolar surgery might be an effective and safe way to aid orthodontic tooth movement.

Three-dimensional spiral computed tomographic imaging: a new approach to the diagnosis and treatment planning of impacted teeth.

INTRODUCTION: The aim of this investigation was to explore the validity of 3-dimensional (3D) spiral computed tomographic (CT) images to examine impacted teeth before surgical or orthodontic treatment. METHODS: Two patients with impacted teeth were examined with both spiral CT and traditional radiographs. RESULTS: 3D CT images clearly showed the impacted teeth, including crown, root neck, and root bifurcation; the labial or palatal location; and the eruption orientation and relationship to the dentition. CONCLUSION: 3D CT images obtained with 3D surface reconstruction of spiral CT images is accurate and effective for examining impacted teeth before orthodontic treatment.

[Differential regulation of P2X3 mRNA expression in the rat trigeminal ganglion after experimental tooth movement].

OBJECTIVE: To investigate the regulation of P2X3 mRNA expression in the trigeminal ganglion sensory neurons after the nociceptive stimulation by orthodontic tooth movement force. METHODS: Male Sprague-Dawley rats weighing 200-250 g were used. The mimic tooth movement appliance was used in the rats of the experiment group. The rats were sacrificed after 4 h, 12 h, 1 d, 2 d, 3 d, 5 d and 7 d after experiment. The expression of P2X3 mRNA was detected by in situ hybridization with an oligonucleotide probe. RESULTS: After force was given to the teeth of rats, the number of P2X3 mRNA positive neurons increased on the first day and reached the peak on the third day; then, the level of P2X3 mRNA expression began to decrease, and after seven days, it returned to the level of the control group. CONCLUSION: The results suggest that the P2X3 mRNA expression is transiently upregulated and anterogradely transported in trigeminal primary sensory neurons after orthodontic tooth movement and that P2X3 receptor may play a role in the pathomechanism of nociception in primary sensory neurons during orthodontic treatment.

Influence of fixed orthodontic treatment on the menstrual cycle of adult females: A prospective longitudinal study.

OBJECTIVE: To investigate the influence of fixed orthodontic treatment on the menstrual cycle, including menstrual cycle length (MCL) and duration of menstrual bleeding (DMB), in adult female patients. MATERIALS AND METHODS: This was a prospective longitudinal study conducted in Chengdu, China. A total of 164 adult women with normal menstrual cycles were recruited in the study, with 79 patients undergoing orthodontic treatment and 85 serving as controls. Data of MCL, DMB, and accompanying symptoms were collected over six consecutive menstrual cycles in each participant. Student's t test, Chi-square test, Moses extreme reaction test, and repeated measures analysis of variance were used for statistical analysis. RESULTS: The MCL of the first menstrual cycle (T1) was significantly elongated by 2.1 ± 0.5 days compared with baseline (P  =  .003, 95% CI [-3.7, -0.5]). Variability of MCL of the orthodontic group at T1 was also significantly greater (range, 15-46 days) than that of the control group (range, 24-36 days) (P < .05). No significant difference in MCL was found in the subsequent five menstrual cycles (T2-T6) compared with baseline, and no significant differences in DMB or other accompanying symptoms were observed throughout the study. CONCLUSION: Fixed orthodontic treatment may influence the MCL of adult females in the first month after bonding, but showed no effect on DMB or subsequent MCL through the follow-ups.

[Functional analysis of novel mutations in PAX9 associated with familial oligodontia].

OBJECTIVE: To gain new insights into the molecular pathogenesis of the 109(InsG) and 139(C--> T) mutations and their roles in familial oligodontia. METHODS: The region of PAX9 paired domain (PAX9PD) was amplified and the expression plasmids were constructed in pGEXlambda -1T by PCR-based cloning. PAX9PD proteins were prepared on the basis of GST instruction. The binding of wild type and two novely mutant PAX9 paired domain to double-stranded DNA targets were analyzed by gel mobility shift assay. RESULTS: Wild type PAX9PD protein bind to the high affinity paired domain recognition sequences, CD19-2(A-ins) and Pax6CON, the 109(InsG) and 139(C--> T) mutant PAX9PD protein were unable to bind to these cognate DNA-binding sites. CONCLUSION: The functional defects in DNA binding of mutant 109(InsG) PAX9 and 139(C--> T) PAX9, as well as loss-of-function of PAX9 most likely result in its haploinsufficiency during the patterning of dentition and the subsequent loss of posterior teeth.