A novel approach of torque control for maxillary displaced incisors.

Effective torque control is crucial for the successful treatment of impacted incisors; however, torque control is often a challenge with the use of conventional bracket systems, especially when the adjacent teeth require opposite torque managements. A novel approach of torque control for adjacent anterior teeth is introduced in this case report. A 12-year-old boy had an impacted maxillary right central incisor with the adjacent teeth severely displaced. The treatment plan was to regain space and pull the impacted incisor into the dentition. An upper removable appliance was first used to regain space for the impacted central incisor, followed by a spontaneous eruption of the impacted incisor. Subsequently, fixed appliances were bonded to level and align the dentition. However, the crown of the maxillary right central incisor was found to be tipped lingually, while the maxillary right lateral incisor was tipped labially. Traditional torque control, including torque bend and the use of a Warren spring, were first used for the correction, but they were ineffective due to the overlap of the root apex of the maxillary central incisor and lateral incisor. After the roots were separated with a V-shaped curve, auxiliary brackets were bonded on the gingival one-third areas of the maxillary incisors and canine with nickel-titanium wires used for the torque control. This approach of using the auxiliary brackets and wires was demonstrated to be efficient and effective in the torque control of adjacent anterior teeth with opposite torque control requirements. The final result and the 2-year follow-up records demonstrated the proper torque of anterior teeth and good and stable dental and profile esthetics.

Asymmetric molar distalization with miniscrews to correct a severe unilateral Class III malocclusion.

Asymmetries are among the most challenging problems in orthodontics. Proper diagnosis is critical to discern first whether the asymmetry is dental or skeletal. If it is dental, one must then determine whether one dental arch or both are at fault. Once diagnosed, the next challenge is determining not only an appropriate treatment plan, but also the appropriate mechanics plan. This aim of this article is to present a patient with a severe asymmetry to emphasize the importance of a problem-based differential diagnosis to develop both a sound treatment plan and a mechanics plan that successfully integrates miniscrews from the start of the process. An 18-year-old woman had a Class III subdivision left malocclusion, an asymmetric lower facial third, and a deviated midline. The treatment plan consisted of asymmetric distalization of the maxillary right and mandibular left posterior dentitions to create space to resolve the deviated midlines, correct the canted occlusal plane, and obtain an ideal occlusion. Active treatment with Clarity ceramic 0.022 × 0.028-in appliances (3M Unitek, Monrovia, Calif), temporary anchorage devices, and a pendulum appliance lasted 22 months. The final result and the 2-year retention records demonstrate that a harmonious facial balance, an attractive smile, ideal occlusal relationships, and a stable outcome were achieved. This case report shows that with proper planning, asymmetric use of temporary anchorage devices in multiple posterior quadrants can be used to obtain molar distalization, and this approach is an effective alternative to dental extraction therapy.

Endoplasmic reticulum stress regulates rat mandibular cartilage thinning under compressive mechanical stress.

Compressive mechanical stress-induced cartilage thinning has been characterized as a key step in the progression of temporomandibular joint diseases, such as osteoarthritis. However, the regulatory mechanisms underlying this loss have not been thoroughly studied. Here, we used an established animal model for loading compressive mechanical stress to induce cartilage thinning in vivo. The mechanically stressed mandibular chondrocytes were then isolated to screen potential candidates using a proteomics approach. A total of 28 proteins were identified that were directly or indirectly associated with endoplasmic reticulum stress, including protein disulfide-isomerase, calreticulin, translationally controlled tumor protein, and peptidyl-prolyl cis/trans-isomerase protein. The altered expression of these candidates was validated at both the mRNA and protein levels. The induction of endoplasmic reticulum stress by mechanical stress loading was confirmed by the activation of endoplasmic reticulum stress markers, the elevation of the cytoplasmic Ca(2+) level, and the expansion of endoplasmic reticulum membranes. More importantly, the use of a selective inhibitor to block endoplasmic reticulum stress in vivo reduced the apoptosis observed at the early stages of mechanical stress loading and inhibited the proliferation observed at the later stages of mechanical stress loading. Accordingly, the use of the inhibitor significantly restored cartilage thinning. Taken together, these results demonstrated that endoplasmic reticulum stress is significantly activated in mechanical stress-induced mandibular cartilage thinning and, more importantly, that endoplasmic reticulum stress inhibition alleviates this loss, suggesting a novel pharmaceutical strategy for the treatment of mechanical stress-induced temporomandibular joint diseases.

Interdisciplinary treatment for an adult with a unilateral cleft lip and palate.

A young man, age 18 years 4 months, with a concave profile, a skeletal maxillary deficiency, and a severe alveolar cleft with an unesthetic appearance of the maxillary anterior teeth was referred for orthodontic treatment. After a detailed review of his pretreatment records, both surgical and nonsurgical treatment plans were presented to the patient, who opted for a nonsurgical interdisciplinary approach. His complex 3-dimensional malocclusion required palatal expansion, dental extractions, and periodontal and prosthodontic consultations and treatment, in addition to comprehensive orthodontic therapy. MBT (Xinya, HangZhou, China) 0.022 × 0.028-in appliances combined with a mini-implant to enhance the orthodontic anchorage were used to level, align, and establish a Class I relationship. After the orthodontic treatment, a combined restorative and periodontal approach was used to enhance the patient's esthetic and functional outcomes. Both the final result and the 1-year follow-up records demonstrate that the treatment goals of establishing proper occlusion, normal function, a balanced profile, better esthetics, and a stable outcome were achieved. The purpose of this case report is to demonstrate that an interdisciplinary treatment protocol can significantly improve the transverse discrepancies and achieve a satisfactory occlusion with a balanced profile in patients with cleft lip and palate.

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.

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.

[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.

Effect of asymmetric force on the condylar cartilage, subchondral bone and collagens in the temporomandibular joints.

This study aimed to define the effects of asymmetric force on rat temporomandibular joints (TMJs). A total of 232 10-week-old rats were used in the experiment. Their left TMJs were kept forward and upward with 40g or 120g. The histological and osteogenic changes, as well as the expression of type I, II and III collagens were observed. Our results showed that the curve of the cartilage thickness changes in the anterior part of the treated side in the heavy force group (HS) decreased first and increased later during the strength and the recovery periods, while the reverse changes were shown in the middle and posterior parts. The cartilage thickness change on the other side in the heavy force group (HO) was the opposite. Additionally, the cartilage thickness change on the treated side and the other side of the light force group (LS and LO) were similar to but not as significantly changed as HS and HO. There were significant differences among the experimental groups. The subchondral bone trabecula also decreased after the pressure loading and removing, then recovered, without significant differences among these groups. Furthermore, more pathological changes such as fractures, bone cysts, the degradation of type II collagen and the increased expression of type III collagen were observed on the treated sides following the application of heavy force. In contrast, more osteogenesis and more active changes were found in the light force group. In conclusion, our study demonstrated that asymmetric force exerted different effects on the cartilage, subchondral bone and collagens of TMJs. Greater changes occurred in the heavy force group, and light force provided more benefits for TMJs remodelling.

[Evaluation of root resorption after palatal expansion by magnetic expansion appliance].

OBJECTIVE: To investigate the root length of posterior teeth after palatal expansion by magnetic expansion appliance. METHODS: A total of 32 patients who accepted palatal expansion with magnetic expansion appliance were enrolled in the study. Pretreatment and post-treatment cone-beam computed tomography (CBCT) images were obtained. A paired t test was used to evaluate the length change, and a group t test was used to compare the tooth lengths of developing and developed teeth. RESULTS: Anchorage teeth showed greater root resorption than non-anchorage teeth, whereas the developed posterior teeth showed reduced resorption. Moreover, the mesial buccal roots of the first molar and first premolar were reduced. No resorption was found in the developing teeth group. CONCLUSION: The magnetic palatal expansion can reduce the root length, particularly of developed root. The developing root of anchorage teeth show greater tolerance to resorption than the developed root. Early palatal expansion treatment with magnetic expansion appliance can reduce the risk of root resorption.

Ameloblastin modulates osteoclastogenesis through the integrin/ERK pathway.

Proteins of the extracellular matrix often have multiple functions to facilitate complex tasks ranging from signaling to structural support. Here we have focused on the function of one of the matrix proteins expressed in bones and teeth, the matrix adhesion protein ameloblastin (AMBN). Transgenic mice with 5-fold elevated AMBN levels in mandibles suffered from root cementum resorption, delamination, and reduced alveolar bone thickness. AMBN gain of function also resulted in a significant reduction in trabecular bone volume and bone mass dentistry in 42 days postnatal mouse jaws. In an in vitro model of osteoclastogenesis, AMBN modulated osteoclast differentiation from bone marrow derived monocytes (BMMCs), and dramatically increased osteoclast numbers and resorption pits. Furthermore, AMBN more than doubled BMMC adhesion, accelerated cell spreading, and promoted podosome belt and actin ring formation. These effects were associated with elevated ERK1/2 and AKT phosphorylation as well as higher expression of osteoclast activation related genes. Blocking integrin α2ß1 and ERK 1/2 pathways alleviated the effects of AMBN on osteoclast differentiation. Together, our data indicate that AMBN increases osteoclast number and differentiation as well as mineralized tissue resorption by regulating cell adhesion and actin cytoskeleton polymerization, initiating integrin-dependent extracellular matrix signaling cascades and enhancing osteoclastogenesis.

[Study on the method of two dimensional polycrylamide gel electrophoresis on rat condylar chondrocyte].

PURPOSE: To investigate the protein profile by two dimensional polycrylamide gel electrophoresis on the rat condylar chondrocyte in vitro. METHODS: The third-passage chondrocytes were harvested from the mandibular condyles of 2-day-old rats in this study. The protein profile of the rat mandibular condylar chondrocytes was examined by two dimensional polycrylamide gel electrophoresis (2-DE-PAGE). The 2-DE gel maps on different pH gradients were obtained. The result of modified coomassi blue-sliver staining and sliver staining was compared using Pdquest 7.1 image analysis software. RESULTS: The results showed that the good protein profile of the condylar chondrocytes was obtained by standard Bio-Rad manual. The protein was mainly in the field from pH4 to pH7. The 1203±86 protein points were examined on 2-DE gel map by modified coomassi blue-sliver staining, and 1769±97 protein points was examined by sliver staining. The silver staining map showed more distinctly but higher background than modified coomassi blue-sliver staining. CONCLUSIONS: The protein profile of the condylar chondrocytes enriches the proteomic database and gives evidence to further proteomic research. The 2-DE map obtained by modified coomassi blue-sliver staining is more suitable for MALDI-TOF mass identification. Supported by National Natural Science Foundation of China (Grant No. C30700963), China Postdoctoral Science Foundation(Grant No.20090461088), Jiangsu Provincial Postdoctoral Science Foundation (Grant No.0802003C) and Nanjing City's Science and Technology Foundation (Grant No.200905011).

[Effect of asymmetry elastic on the maturation of bone collagen and mineralization in condyle of adult SD rat].

PURPOSE: The aim of this investigation was to study the osteogenesis activation following asymmetric inter-maxillary elastic on the subchondral bone of adult SD rats. METHODS: Twenty SD ten-week old rats were used in this study (eight rats loading 0.39 N elastic force, another eight rats loading 1.18 N elastic force, the other four rats without loading as control group). The extra-joint device was fixed on the right side by surgery. Tetracycline, calcein and xylenol orange were intraperitoneally injected on one day before surgery, one day before device removal and one day before sacrifice. Masson trichrome staining and in vivo fluorescence technique were used to detect the osteogenesis. RESULTS: The results of bone collagen maturation and velocity of osteogenesis were different from the control group after force loading. Bone collagen showed better maturity in force-loading side and light force induced more active osteogenesis. CONCLUSIONS: The results suggest that even in the adult SD individuals, the subchondral bone still shows remodeling ability to adapt the various mechanical environments. Stress increases the maturity of bone collagen while rotation inhibits maturity. Mechanic force promotes the osteogenesis, especially the light force.

[Effect of asymmetry traction on the expression of type II collagen in adult rat condyle].

OBJECTIVE: The aim of this investigation was to study the expression of collagen type II in the cartilage of mandibular condyle following asymmetric inter-maxillary traction. METHODS: Two hundred and twenty SD rats were used in this study (one hundred and four rats loading 0.39 N elastic force, another one hundred and four rats loading 1.18 N elastic force, while twelve rats for control). The extra-joint device was fixed on the right side by surgery. Half of the experimental group was killed at 3, 7, 14, 28 days. The devices were removed at the 28th day in the rest rats, and the rats were sacrificed at 3, 7, 14, 28 days after removing the device. The type II collagen expression levels of all the joints were measured using immunohistochemical techniques. RESULTS: The positive expression of the type II collagen was mainly observed in the cytoplasm of chondrocyte, especially in maturative and hypertrophic layer. The expression intensity was different in different stages and different sides. Both of the two experimental groups showed the same tendency, while the changes in the light force group were more obviously than the heavy force group. In the right side (force-loading side), the type II collagen expression decreased at the early force-loading period. After the device was removed, the expressions increased immediately but then reach the lowest level. The expression almost recovered to normal level at the end of experiment. In the left side (none force-loading side), the expression remained increasing after force-loading and reached the peak at the 14th day. CONCLUSION: These results suggest that even in the adult individuals, the chondrocyte showed reaction to the mechanical force by altering type II collagen expression patterns and it may be the cause of the cartilage remolding after asymmetric inter-maxillary traction. A forward elastic force showed a depressant effect in matrix synthesis, and heavy force had stronger effect. But the rotation of condyle accelerated the matrix synthesis.

[Early-response of the condylar chondrocyte under cyclic uniaxial compressive stress].

OBJECTIVE: To investigate the protein profile after treatment of the cyclic uniaxial compressive stress on the rat condylar chondrocyte in vitro. METHODS: The third-passage chondrocytes were harvested from the mandibular condyles of 2-day-old rats, and a cellular compressive stress device (self-made four-point bending system) was used to apply stress on cells at 2000 microstrain and 4000 microstrain (0.5 Hz frequency) for 60 min. The early effects of cyclic uniaxial compressive stress on the protein profile of the rat mandibular condylar chondrocytes were examined by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser-desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). RESULTS: The results showed that the protein profile of the condylar chondrocyte did not change statistically in 2000 microstrain group. In 4000 microstrain group, the protein profile of the condylar chondrocyte was changed. Three new proteins appeared. Five proteins disappeared. Twenty-two proteins were down-regulated and 7 proteins were up-regulated (P < 0.05). The eight different protein spots were identified by MALDI-TOF-MS. It included cytoskeleton protein (gamma-actin and vimentin), glycometabolism protein (alpha enolase and stress-70 protein) and signal transduction protein (Raf kinase inhibited protein, RKLP). CONCLUSIONS: There were significant alternations of the protein profile in the rat condylar chondrocyte after the 4000 microstrain cyclic uniaxial compressive stress loading for 60 min. These different proteins might take part in the early response to the cyclic uniaxial compressive stress.

[Early effects of the cyclic uniaxial compressive stress on Actin and Vimentin of the rat condylar chondrocytes].

OBJECTIVE: To investigate the early effects of the cyclic uniaxial compressive stress on Actin and Vimentin of the rat condylar chondrocyte. METHODS: The third-passage chondrocyte were harvested from the mandibular condyles of 2-day-old rats, and a cellular compressive stress device was used to apply stress on cells at 4 000 microstrain for 15, 30, 60, 120, 240 min. The early effects of the cyclic uniaxial compressive stress on Actin and Vimentin of the rat mandibular condylar chondrocytes were examined by laser scanning confocal microscope (LSCM), immunofluorescence technique and Western blot. RESULTS: The expression of fluorescent light of cys-toskeleton protein changed obviously with 4000 microstrain compressive stress loading. The expression of Actin significantly decreased in 60 min, and the expression of Vimentin decreased in 30 min. Then the expression of these two protein recovered in 120 min. CONCLUSION: There are time-responsiveness between the 4000 microstrain compressive stress stimulate and Actin, Vimentin. It shows the expression of Actin and Vimentin down-regulated at first under the compressive stress, then increased by feedback. It hints that there are "self-regulate" mechanisms in the cell response to mechanics stimulate.

[Early effects of the cyclic uniaxial compressive stress on Stress70/GRP75 in the rat condylar chondrocytes].

PURPOSE: The purpose of this study was to investigate the early effects of the cyclic uniaxial compressive stress on Stress70/GRP75 in the rat condylar chondrocyte. METHODS: The third-passage chondrocytes were harvested from the mandibular condyles of 2-day-old rats for this study, and a cellular compressive stress device (self-made four-point bending system, Patent No.01129166.4 & 01256849.x) was used to apply stress on cells at 4000 microstrain (0.5 Hz frequency) for 0, 15, 30, 60, 120, 240 minutes respectively. The early effects of the cyclic uniaxial compressive stress on Stress70/GRP75 in the rat mandibular condylar chondrocytes were examined by Western blot and image analysis. One-way ANOVA was used for statistical analysis. RESULTS: The results showed that the expression of Stress70/GRP75 changed significantly with 4000 microstrain compressive stress loading. The gray scale value of protein band at 0 minute was 114.2+/-5.08, significantly decreased to 86.1+/-5.09 (P<0.001) after 30 minutes, and then gradually increased to 104.0+/-4.41 (P<0.01) at 60 minutes. The expression of Stress70/GRP75 up-regulated to 134.5+/-3.74 (P<0.001) at 120 minutes, and continued to increase within 240 minutes. CONCLUSION: There is time-dependent response between the 4000 microstrain compressive stress stimulate and Stress70/GRP75. The expression of Stress70/GRP75 inhibited initially under the compressive stress, and then increased by feedback with the increased loading time.

[The effect of Class III intermaxillary orthopedic force loading on the maxilla of puberty rhesus: a histomorphologic study].

PURPOSE: The purpose of this study is to quantitatively study the remodling changes of circummaxillary sutures of puberty rhesus loaded with Class III intermaxillary orthopedic force. METHODS: The animal model was established with 6 puberty female rhesus, which were randomly divided into experimental group (wore Class III Twin-block magnet appliance, each 2 rhesus for 3 and 6 months respectively) and control group(did not wear any appliance, each 1 rhesus for 3 and 6 months respectively ). The specimens were stained by hematoxylin and eosin, and image analysis system (IAS) was used in the quantatitive study of sutures width and cell density. One-way analysis of variance (ANOVA) was employed, and LSD analysis was used when interclass significance was found. RESULTS: Compared to the control group, different changes were shown in different sutures.New bone formation was observed in all experimental animal. There was no significance difference between palatomaxillary suture and pterygomaxillary suture in cellular density (P>0.05). Zygomaticotemporal suture showed no difference between 3-month experimental group and control group;however, 6-month experimental group was significantly higher than 3-month experimental group (P<0.01).For frontomaxillary suture, 3-month experimental group was significantly higher than the control group, and 6-month experimental group was significantly higher than later one (P<0.01).Zygomaticomaxillary suture in the experimental group was significantly higher than the control group (P<0.01);meanwhile, 3-month experimental group was significantly higher than 6-month experimental group (P<0.05). Furthermore, the width of sutures were different in these groups. Palatomaxillary suture became significant narrower in 3-month experimental group (P<0.01),but zygomaticotemporal suture became significant wider (P<0.01). The width of sutures restored at 6th month (P>0.05). The width of pterygomaxillary suture was not different between 3-month experimental group and the control group (P>0.05),but it became significant wider in 6-month experimental group (P<0.05). Frontomaxillary sutures of the experimental group were significantly narrower than the control group, and 6-month experimental group was significantly narrower than 3-month experimental group (P<0.01). For zygomaticomaxillary suture, the experimental groups were significantly wider than the control group;meanwhile, there was no difference between the experimental groups. CONCLUSION: Proper Class III orthopedic force can promote the physiological remodling of maxillary sutures.