ABSTRACT
BACKGROUND:Temporomandibular joint disorders are closely related to high stress in temporomandibular joint.With the change of molar position after tooth reduction extraction,the establishment of new occlusal relationship often leads to the change of internal stress environment of the temporomandibular joint. OBJECTIVE:To analyze the stress distribution of temporomandibular joint in patients undergoing orthodontic reduction tooth extraction with different degrees of molar forward movement using the three-dimensional finite element model of the maxillary complex and temporomandibular joint. METHODS:A case of individual normal occlusal patient was selected from the Orthodontics Department of Qingdao Municipal Hospital,Shandong Province,and the finite element models of 1/3 anterior molar space(extraction of four second premolar teeth)before and after reduction and 2/3 anterior molar space(extraction of 4 second premolar teeth)after reduction were established based on the cone-beam CT and MRI data.ABAQUS software was used to analyze the stress distribution of various parts of the temporomandibular joint during the interposition of tooth tips. RESULTS AND CONCLUSION:The stress distribution of the condyle,articular disc,and osteoarticular fossa in the model before and after the reduction was basically the same.The stress of the condyle was mainly distributed in the anterior and apical part of the condyle,the stress of the articular disc was mainly distributed in the middle band and lateral part of the articular disc,and the stress of the articular fossa was mainly concentrated in the anterior and apical part of the articular fossa.However,the equivalent stress value of the condyle,articular disc and articular fossa decreased after reduction.After orthodontic reduction extraction,the equivalent stress values of condyle and articular disc in the 1/3 anterior molar space model were smaller than those in the 2/3 anterior molar space model.From the perspective of biomechanics,orthodontic reduction extraction can reduce the stress of the temporomandibular joint and provide a good biomechanical environment.
ABSTRACT
BACKGROUND: Pathological mechanism of ossification of the ligamentum flavum is unclear. There is no effective drug or non-surgical treatment in clinical practice. Current studies have found that osteopontin and autophagy play an important role in the process of osteogenesis, but their role in ossification of the ligamentum flavum has not been elucidated. OBJECTIVE: To seek for the potential target of drug therapy by exploring the mechanism of ossification of the ligamentum flavum. METHODS: (1) Surgical specimens of the ligamentum flavum were taken from patients with ossification of the ligamentum flavum, thoracic vertebrae or simple lumbar disc herniation undergoing posterior total laminectomy and decompression. These specimens were divided into two groups: An ossification group and a non-ossification group. Eight specimens from each group were collected. Osteopontin, osteocalcin and autophagy indexes Beclin-1, LC3 and P62 were stained by immunohistochemistry. (2) The ligamentum flavum cells were isolated and cultured by adherence method. The third generation cells were treated with osteopontin at different concentrations for different time to construct an in vitro model of ligamentum flavum ossification. (3) Autophagy inhibitor 3-methyladenine with different concentrations was used to intervene with non-ossified ligamentum flavum cells, followed by induction with 100 μg/L osteopontin. Western blot assay was used to detect the expression of alkaline phosphatase, osteocalcin. (4) Non-ossified ligamentum flavum cells were induced with 100 μg/L osteopontin, and the induction was terminated at 0, 15, 30, 60, and 120 minutes, respectively. The phosphorylation of ERK1/2, JNK and P38, which are important molecules in the MAPK signaling pathway, was detected by western blot. (5) Finally, after inhibition by ERK1/2 phosphorylation blocker U0126, the expression of alkaline phosphatase and osteocalcin was detected by western blot after induction with 100 μg/L steopontin. RESULTS AND CONCLUSION: (1) Immunohistochemical staining of osteopontin and osteocalcin in ossified and non-ossified ligamentum flavum was positive. In the ossified ligamentum flavum, Beclin-1 was positive, but LC3 and P62 were not. Beclin-1, LC3 and P62 were all positive in the non-ossified ligamentum flavum. (2) The expression of alkaline phosphatase and osteocalcin in the ossified ligamentum flavum cells was higher than that in the non-ossified ligamentum flavum cells. Osteopontin could induce ossification of the ligamentum flavum in a concentration- and time-dependent manner. (3) The degree of ossification was negatively correlated with the degree of autophagy, that is, the more obvious autophagy was, the weaker ossification was. (4) Osteopontin could phosphorylate the MAPK signaling pathway in a time-dependent manner. After inhibiting the phosphorylation of MAPK, osteopontin could still induce the ossification of ligamentum flavum cells. To conclude, in the process of ligamentum flavum ossification, the upstream and downstream relationships of ERK1/2, osteopontin, alkaline phosphatase and osteocalcin molecules in signaling pathway are ERK1/2→osteopontin→osteocalcin/alkaline phosphatase.
ABSTRACT
BACKGROUND: Current studies have shown that ultrasound-guided paravertebrospinai nerve block widely used has a significant effect in the clinical treatment of thoracolumbar zoster-associated pain. OBJECTIVE: To systematically evaluate the efficacy and safety of ultrasound-guided paravertebral nerve block in the treatment of thoracolumbar zoster-associated pain and to provide reference for clinical treatment. METHODS: We searched relevant literature in PubMed, The Cochrane Library, EMBASE, China National Knowledge Infrastructure (CNKI), WanFang Data, China Science and Technology Journal Database (VIP) and Chinese Biomedical Literature Database (CBM). The limit of searching time was from inception until January 1, 2019. Randomized controlled trials addressing ultrasound-guided paravertebral nerve block (experimental group) versus drug therapy (control group) for the treatment of acute zoster-associated pain or postherpetic neuralgia were collected according to the criteria for inclusion and exclusion. Literature quality was assessed according to Cochrane Handbook 5.1.0 bias risk assessment tool. The literature data were analyzed using Revman 5.3 software through a Meta-analysis. RESULTS AND CONCLUSION: A total of 11 randomized controlled trials involving 916 patients met the inclusion criteria. The results of Meta-analysis showed that compared with the control group, the ultrasound-guided paravertebral nerve block group had better analgesic effect and the optimal analgesic effect appeared within 1-4 weeks. A random effects model was then used [1st week: Mean difference (MD)=-0.91, 95% confidence interval (Cl) (-1.22, -0.61), P < 0.000 01; 2nd week: MD=-1.11, 95%C/(-1.52, -0.70), P < 0.000 01; 3rd week: MD=-1.26, 95%C/(-1.79, -0.74), P < 0.000 01; 4th week: MD=-0.90, 95%C/(-1.57, -0.24), P=0.007], At the same time, the quality of sleep and the effective rate of treatment were improved, and a fixed effects model was used [odds ratio=3.63, 95%C/(2.38, 5.53), P < 0.000 01]. The statistical results showed significant difference. There was no increase in post-treatment adverse reactions. Therefore, ultrasound-guided paravertebral nerve block is safe and effective for the treatment of zoster-associated pain in the thoracolumbar region.
ABSTRACT
Objective: To explore the feasibility and effects of teaching with tissue construction thinking of organ in histology and embryology. Methods: One hundred twenty students from four year 2017 clinical major classes in Mudanjiang medical university, who participated in the study of histology and embryology, were consecutively selected. Traditional teaching mode which is lecture-base learning was used in the control class, while the experimental class was taught by tissue construction thinking of organ, the evaluations were taken at the end, including questionnaires and exam scores of four classes. Results: The experimental class was distinctly superior to the control class in learning interest, innovation ability, self-study ability, manipulative ability, psychological quality and team spirit (P<0.01), and in exam scores also (P < 0.05). Conclusion: Tissue construction thinking of organ is particulary adapted to the teaching of histology and embryology. The thinking can play a vital role in resolving the problems in teaching of Histology and embryology. And it will also help to cultivate high-quality applied medical talents with innovative ability.
ABSTRACT
BACKGROUND:Tougu Xiaotong capsule is the clinical prescription for the treatment of osteoarthritis, however, its mechanism has not been fuly elucidated. Urokinase type plasminogen activator system which participated in the degradation of the extracelular matrix of articular cartilage and hyperplasia of joint synovium plays an important role in the pathological process of osteoarthritis. OBJECTIVE: To determine the effect ofTougu Xiaotong capsule on urokinase-type plasminogen activator system in knee cartilage tissues of knee osteoarthritis rats. METHODS: Of 144 Sprague-Dawley rats, 120 rats were randomly made into models of knee osteoarthritisvia intra-articular injection of papain, and randomly assigned to model group,Zhuanggu Guanjie Wan group [1.2 g/(kg?d)], low-doseTougu Xiaotong capsule group [0.092 g/(kg?d)], moderate-doseTougu Xiaotong capsule group [0.184 g/(kg?d)] and high-doseTougu Xiaotong capsule group [0.368 g/(kg?d)]. Each group contained 24 rats. Every 2 weeks was considered as a course, with a 2-day interval, totaly 4 courses. The remaining 24 normal rats were included in the blank group. After every two courses, a batch of experimental animals was sacrificed. The pathological changes were observed folowing staining with hematoxylin and eosin. The positive cels of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor and plasminogen activator inhibitor were measured by immunohistochemistry. The protein levels of urokinase-type plasminogen activator, urokinase-type plasminogen activator receptor and plasminogen activator inhibitor were measured by western blot assay. RESULTS AND CONCLUSION:Mankin’s score was significantly lower in theTougu Xiaotong capsule group and Zhuanggu Guanjie Wan group compared with the model group (P < 0.01), in a time-dependent manner. Immunohistochemical staining indicated that the positive cels of urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor were significantly decreased, but plasminogen activator inhibitor was significantly increased in theTougu Xiaotong capsule group andZhuanggu Guanjie Wangroup in a time-dependent manner. Western blot assay results had an identical trend to immunohistochemistry. These indicated thatTougu Xiaotong capsule showed preventive and therapeutic effects on osteoarthritis by regulating urokinase-type plasminogen activator system.
ABSTRACT
BACKGROUND: Chinese medicine Gukang prescription has a clear effect on clinical treatment of osteoporosis, but the therapeutic pathway is stil unclear. OBJECTIVE:To investigate the effects of Chinese medicine Gukang on the expression of receptor activator of nuclear factor kappa B ligand and osteoprotegerin by regulating core binding factor alpha 1 expression to control the growth and development of osteoblasts. METHODS:Sprague-Dawley neonatal rats within 24 hours after delivery were used for the separation and culture of osteoblasts. Adult Sprague-Dawley rats were used to prepare drug-containing serum, and then divided into two groups randomly:normal control group and Gukang group. Rats in the normal control and Gukang groups were intragastrical y administrated with extract of Gukang prescription and normal saline based on rat’s body surface area, for 1 consecutive week. Two hours after the last administration, blood samples were taken from the heart. Then the serum was col ected. Osteoblasts at passage 3 were confirmed with alkaline phosphatase assay and digested. After counting and planting, al osteoblasts were divided into two groups and treated with col ected serum for 72 hours. Proliferative rate of osteoblasts was detected by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Secretion of alkaline phosphatase was detected by using enzyme linked immunosorbent assay and corrected with the corresponding absorbance value. mRNA expression of core binding factor alpha 1, receptor activator of nuclear factor kappa B ligand and osteoprotegerin were detected by using reverse transcription-PCR in al groups. RESULTS AND CONCLUSION:mRNA expression of osteoprotegerin and core binding factor alpha 1 in the Gukang group was significantly higher than that in the normal control group, but protein and mRNA expression of receptor activator of nuclear factor kappa B ligand were dramatical y lower in the Gukang group compared with the normal control group (Pcore binding factor alpha 1, thereby adjusting the expression of receptor activator of nuclear factor kappa B ligand and osteoprotegerin, which may be one of the mechanisms underlying Gukang treatment for osteoporosis.
ABSTRACT
BACKGROUND:One-legged standing with eyes closed is a method to test the muscle strength and the ability of body balance, it is considered to be an important quality indicator for evaluation of adults and elderly balancing capability in our country. A lot of works have been done in many provinces and cities, but there is a lack of in-depth studies. OBJECTIVE:To review the research progress of one-legged standing with eyes closed, to analyze its problem used in the physical fitness test and to prospect the future direction of the related researches. METHODS:A computer-based search on CNKI database and Elsevier database was undertaken to identify the article of balance capacity. The key words were“eyes closed and single legged standing, balance ability, physical fitness test”. Total y articles were searched and checked primarily, and those meeting the criteria were looked up. RESULTS AND CONCLUSION:The standard of one-legged standing with eyes closed for the male is higher than that for the female. Some elderly just stand for a short time in the test, and thus it is difficult to distinguish the balance ability. Elderly balance is significantly lower than that in young people. The same test method for adults and elderly people is employed, but whether it is scientific or not should be further studied. Various indicators in the test of one-legged standing with eyes closed have low correlation. For the above reasons, further studies should be made before the test of one-legged standing with eyes closed becomes a valuable measurement of the balance ability in the national physique.
ABSTRACT
BACKGROUND:Sarcopenia is the muscle loss in the elderly with aging, and it is closely related to the degradation of muscle function in the elderly. The research on the mechanism of sarcopenia as wel as effect of movement intervention is developed. OBJECTIVE:To summary the mechanisms of sarcopenia cel level as wel as the effect of movement intervention. METHODS:A computer-based retrieval was conducted on CNKI database and PubMed database for literatures on sarcopenia and elderly resistance training from January 2000 to December 2012. The key words were “sarcopenia, muscle, resistance training, aging, protein metabolism”. The literatures on sarcopenia, protein metabolism and resistance training were included, and the obsolete and repetitive literatures and the literatures lack of credibility were excluded. Final y, 58 literatures were included for analysis. RESULTS AND CONCLUSION:Resistance training can inhibit sarcopenia to a certain extent, so that to increase muscle mass in the elderly and promote the recombinant of motor units. But the recombinant is limited to the mutual conversion between the type Ⅱa and Ⅱb fibers. Resistance training combined with protein supplement can effectively promote elderly muscle reconstruction;the elderly muscle anabolic response confrontation reaction after resistance training is slower than young people, but the inflammatory response after training is stronger than younger people. However, Omega-3 has a good effect on the elimination of such inflammatory response.
ABSTRACT
BACKGROUND:Tooth wear is the physiological change that accompanied by a person’s life, type and nature, maxil ary and mandibular occlusion status, physical status, and living environment may affect it. OBJECTIVE:To review the occurrence and development of tooth wear, as wel as research on the morphology of wear surface. METHODS:The PubMed database was searched by the first author for the articles from January 1952 to December 2012. The articles on the generation of tooth wear facets, macroscopic and microscopic studies of occlusal wear facets, wear measurement method, relationship between tooth wear and oral diseases, and application of tooth wear facets in forensic research were included. The key words were“tooth, wear, diet, information, dentistry, anthropology”in English. A total of 59 articles were included according to the inclusion criteria for review. RESUTLS AND CONCLUSION:With the development of wearing, some oral clinical symptoms may occur. Just as there are no same fingerprints in the world, the individual tooth wear facet is unique. Therefore, the research on occlusal wear facets has great significance for understanding the diet habits, cultural development, age and other information, as wel as for dentistry, anthropology and forensic science. The macroscopic and microscopic study of tooth wear surface can provide a large amount of individual information. The current studies on tooth wear facets cannot ful y exhibit al the implicated information, so the further studies are needed.
ABSTRACT
BACKGROUND:Sclerostin can negatively regulate the bone metabolism, and the sclerostin monoclonal antibody can antagonize the negative regulation effect, inhibit bone resorption and promote bone formation. OBJECTIVE:To explore the mechanism and application progress of sclerostin monoclonal antibody in the treatment of osteoporosis. METHODS:An online search of PubMed database, CNKI database, VIP database and Wanfang database between May 2005 and May 2013 was performed by the first author to search the related articles with the key words of“osteoporosis, antibody, sclerostin, Wnt, SOST”in both English and Chinese. Articles related to sclerostin monoclonal antibody were included. For the articles in the same field, those published earlier or in the authorized journals were preferred. RESULTS AND CONCLUSION:A total of 170 articles were obtained after initial search, and final y 54 articles related to sclerostin monoclonal antibody were included for review according to the inclusion criteria. The sclerostin can block Wnt pathway through combining with low-density lipoprotein receptor-related protein 5/6, thus inhibiting the differentiation and mineralization of osteoblasts. By specifical y binding to sclerostin, the sclerosin monoclonal antibody can indirectly promote bone formation and restrain bone absorption which has great significance in the treatment of osteoporosis. Meanwhile, compared with the other treatment method, the specific targeting of sclerostin and the binding specificity of sclerostin monoclonal antibody provide application advantages for the treatment of osteoporosis.
ABSTRACT
BACKGROUND:Pathophysiological mechanisms after spinal cord injury are very complex, so there is no compressive and in-depth understanding on it. OBJECTIVE:To study the effect of dura mater spinalis integrity on cytokine levels in the cerebrospinal fluid of animal models of spinal cord injury. METHODS:The white rabbit models of spinal cord injury were established using clamp compression method, and then the models were randomly divided into four groups:no dura mater spinalis defect group, dura mater spinalis defect group, dura mater spinalis defect composite with membrane repairing group and dura mater spinalis defect composite with autologous fascia repair group. Enzyme-linked immunosorbent assay was performed to detect the changes of levels of cytokines (interleukin-6, interleukin-10 and tumor necrosis factorα) in the cerebrospinal fluid at 30 minutes, 1, 3, 6, 12 and 36 hours after surgery. RESULTS AND CONCLUSION:The levels of interleukin-6, interleukin-10 and tumor necrosis factorαin the cerebrospinal fluid of the dura mater spinalis defect group, dura mater spinalis defect composite with membrane repairing group and dura mater spinalis defect composite with autologous fascia repair group were significantly lower than those of the no dura mater spinalis defect group at 6 hours after surgery (P0.05). The results indicate that maintaining the integrity of dura mater spinalis of the spinal cord injury model can affect the levels of interleukin-6, interleukin-10 and tumor necrosis factorαin the cerebrospinal fluid, thus inhibiting the inflammatory response.
ABSTRACT
BACKGROUND:Previous studies from Shaanxi Institute of Ophthalmology have shown that ostrich cornea has the advantages to be developed into the alternatives of human corneal material. OBJECTIVE:To determine the potential toxic effects of ostrich corneal stromal scaffold on cel s. METHODS:Cel culture methods were used to culture L-929 cel s in the extracts of ostrich acel ular corneal stroma which was dried and dehydrated. 3-(4,5)-Dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide assay was used to evaluate the growth and proliferation of cel s after cultured for 1, 2 and 3 days. RESULTS AND CONCLUSION:After the cel s were cultured in the extracts of ostrich acel ular corneal stroma subjected to dryness and dehydration for 1, 3 and 5 days, and the toxicity level of cultured cel s was graded as level 1. The cytotoxicity test was conducted according to the“National Standard of the People's Republic of China GB/T16886.5-2003”. After cultured in the extracts of ostrich acel ular corneal stroma, a smal number of cel s were round in shape and loosely adherent without intracytoplasmic granules, and cel lysis could be observed occasional y. The results of 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide assay showed that the ostrich acel ular corneal stromal scaffold which was dried and dehydrated had level 1 of cytotoxicity and could be considered as a qualified material.
ABSTRACT
BACKGROUND:Previous studies have confirmed the presence of bis-(3'-5')-cyclic dimeric guanosine monophosphate signaling pathway in Streptococcus mutans, which construct the streptococcus mutans gcp gene knockout strains. OBJECTIVE:To compare the gene expression differences between Streptococcus mutans wild strains and gcp mutant strains, and to screen the biofilm-related genes from them for the fol ow-up study. METHODS:The total RNA of two kinds of strains were extracted and stained with cy3 and cy5 respectively after reverse transcription. The gene chip was scanned after hybridization and the differential gene were obtained through the data analysis. The different expression genes were verified by real-time PCR. RESULTS AND CONCLUSION:Differential genes were mainly relative about glucose metabolism and biofilm formation. We selected two genes for real-time PCR verification. The PCR results were consistent with the microarray results. After Streptococcus mutans gcp gene knockout, the gene expressions of gcp mutant strains were upregulated and the gene expressions of phosphotransferase system were downregulated, this result suggested that two different genes were related with the c-di-GMP signal pathway downstream.
ABSTRACT
BACKGROUND:Recent studies found that some factors play important role in the process of denervated muscle atrophy, especial y the feak-headbox transcription factor, is the key element to regulate the denervated muscle atrophy. OBJECTIVE:To investigate the effect of RNA interference on inhibiting feak-headbox 3a gene expression in vitro. METHODS:The myoblast cel line L6 were cultured in the 6-wel cel culture plates, then pEGFP-N1 and smal interfering RNA recombinant plasmid with the same ratio was transfected under the Lipofectamine2000 mediation to optimize the transfection efficiency of the detection system;2μg smal interfering RNA recombinant plasmid of feak-headbox 3a gene were transfected with myoblast cel line L6 for 48 and 72 hours. RESULTS AND CONCLUSION:At 48 hours after pEGFP-N1 and siRNA recombinant plasmid transfection, a large number of bright green fluorescent displayed under fluorescence microscope with higher transfection efficiency. Real-time quantitative PCR analysis showed that there were significant differences in the sequences of feak-headbox 3a-Ⅰ, feak-headbox 3a-Ⅱ, feak-headbox 3a-Ⅲ, feak-headbox 3a-Ⅳ on feak-headbox 3a mRNA when compared with the control group at 48 and 72 hours after trasfection (Phours after transfection when compared with that at 48 hours after transfection. Western Blot gray analysis showed that there were significant differences in sequences of feak-headbox 3a-Ⅰ, feak-headbox 3a-Ⅱ, feak-headbox 3a-Ⅲ, feak-headbox 3a-Ⅳ on feak-headbox 3a mRNA when compared with the control group at 48 and 72 hours after trasfection (Psignificantly inhibit the fork-head transcription factor feak-headbox 3a gene expression, and the inhibition effect of feak-headbox 3a gene smal interfering RNA recombinant plasmid transfected with the sequence on the mRNA and protein level of feak-headbox 3a is not clear, which can provide new idea for the gene therapy of RNA mediated denervated skeletal muscle atrophy.
ABSTRACT
BACKGROUND:Posterior arch length deficiency is closely related to the formation and development of malocclusion. OBJECTIVE:To measure the posterior arch length in individual normal occlusions of adults in Lanzhou. METHODS:A total of 102 current col ege students with individual normal occlusions, with a mean age of (19.33±2.67) years (range 18-24 years), including 47 males and 55 females from Gansu Province, were chosen to take lateral cephalograms. Al research objects were divided into three groups according to mandibular plane angle:high angle group (Frankfort mandibular-plane angle>32°), low angle group (Frankfort mandibular-plane angleRESULTS AND CONCLUSION:Posterior arch length of maxil ary arch was slightly longer in male group than that in female group, and the difference was not significant (P>0.05). The posterior arch length of mandibular arch was slightly longer in male group than that in female group, but the difference was no significant (P>0.05). Comparison between groups revealed that the posterior arch length of low angle mandibular arch was significantly longer than that of high angle mandibular arch in male group, and the difference was significant (P<0.05). The results indicate that the gender wil not influence the development of posterior arch length. Different vertical facial types and different genders have different posterior arch length in individual normal occlusions of adults
ABSTRACT
BACKGROUND:Individuals with different vertical facial types have different chin morphologies. For the individuals with different vertical facial types, what is the most beautiful chin morphology? OBJECTIVE:To evaluate the effects of vertical facial types and chin morphology on facial profile attractiveness. METHODS:Three beautiful females were selected, including one with high mandibular angle, one with average angle and one with low angle. Their facial profile photographs were taken. A series of new pictures were generated by the smal scale (2 mm per unit) modification of soft tissue chin in the sagittal direction and vertical direction. Raters consisting of 17 orthodontists and 35 laypersons were selected for aesthetic ratings, in order to evaluate the facial profile attractiveness of the individuals with different vertical facial types. RESULTS AND CONCLUSION:There was no esthetic difference of vertical change in female with high angle;while slightly protrude chin was perceived to be more beautiful than retruded chin. For the female with average angle, lower chin was more attractive than higher chin;slightly protruded chin was beautiful than excessive protruded chin and retruded chin. For the individual with low angle, higher chin was preferred by raters;slightly protruded chin was more beautiful than excessive protruded chin and retruded chin.The results indicate that the effects of vertical facial types and chin morphology to facial profile attractiveness are different. In clinical orthodontic, vertical facial types should be taking into consideration to change the chin morphology of the patents, in order to obtain better profile attractiveness.
ABSTRACT
BACKGROUND:Bone mass deficiency is common during implantation in the maxil ary posterior region. Some patients do not want to accept extra surgery for increasing bone because of surgical trauma or medical expenses. Technology of the tilted implant has been proposed, but it has not been recognized and has a lack of relevant evidence. OBJECTIVE:To investigate the stress distribution of per-implant bone which is subjected to different loading conditions when the different abutment angulations are applied, and to analyze the safety factor of different implants to verify the feasibility of the tilted implant in the maxil ary posterior region. METHODS:The finite element models of the different angulate abutments were established in commercial software packages. The safety factor of implant in the same power load was observed, and stress and strain condition of the implant and the surrounding bone was also observed. RESULTS AND CONCLUSION:With the increased abutment angulation, the maximum strain of pre-implant bone was significantly increased, and the safety factor of implant decreased gradual y. Thus, the tilted implant is not recommended in the maxil ary posterior region.
ABSTRACT
BACKGROUND:The stress distribution in the periodontal ligament of bending root can provide reference for the size and manner of force in orthodontic treatment. On this account, it can optimize the design of orthodontic force. OBJECTIVE:To analyze the stress distribution of root and periodontal ligament in the bending roots of the maxil ary first molar under different orthodontic forces. METHODS:The maxil ary first molars with normal roots and bending roots were selected, and then the finite element models of maxil ary first molars and periodontal ligaments were established through CT scan and Workbench 11.0 finite element analysis software. The models were loaded with six different methods to analyze the stress distribution. RESULTS AND CONCLUSION:The stress distribution of bending root was mainly concentrated in the tooth neck, fol owed by the apex. During the overal tooth movement, the stress was smal est on the root, periodontal ligament and alveolar bone. Correction of bending roots needs more accurate positioning and traction.
ABSTRACT
BACKGROUND:With the development of modern orthodontics, to invent an efficient appliance is the focus in recent studies. Transmission straight wire appliance was born on this background. This appliance can accelerate occlusion and shorten treatment duration. The relationship between distal width and angulation of gable bends of main arch wire needs to study in depth. OBJECTIVE:To establish three-dimensional finite element model of transmission straight wire appliance with better biological and mechanical similarity, and to obtain the relationship between distal width and angulation of gable bend of main arch wire. METHODS:By using scanning of spiral CT with 64 rows, the sectional image data in DICOM format of maxil ary dentition and maxil ae of the volunteers (Class Ⅱ, division 1) were obtained. With the help of Ansys workbench 13.0, Mimics 10.01, Unigraphics NX and Geomagic Studio 8.0 softwares, the three-dimensional finite element model including transmission straight wire appliance, bend, Australian Orthodontic Wire, maxil ae, maxil ary tooth and periodontal ligament was established in Windows XP Service Pack 3 system. RESULTS AND CONCLUSION:A three-dimensional finite element model of transmission straight wire appliance was established, which consisted of 250 929 elements and 657 766 nodes. Furthermore, three-dimensional finite element model had higher geometric similarity and mechanical similarity, as wel as the advantages of adding or subtracting components according to the requirement of the research. The model was conductive to analyze the mechanical system of transmission straight wire appliance and guide the clinical application and appliance modification.
ABSTRACT
BACKGROUND:Studies have shown that the application of electrical stimulation of peripheral nerve fibers can recover partial muscle functions due to the loss of central nervous control. OBJECTIVE:To verify the feasibility of selective nerve excitatory effectively used the symmetric biphasic pulses under the bipolar electrodes stimulation of 1 mm. METHODS:Eight adult Wistar rats were selected to expose the sciatic nerves after anesthesia and then the electrodes were placed on the sciatic nerves careful y to establish the model of selective nerve stimulation. Experimental electrode was homemade Cuff bipolar electrode, and the electrode stimulators were Grass S88 stimulator and AWG2005 arbitrary waveform signal generator. The two-way dual-electrode stimulation was used. The distance between two electrodes was 1 mm, and the stimulation waveform was symmetric biphasic pulse with the width of 0.2 ms. The output pulse amplitude, pulse width and delay could be adjusted. The stimulation intensity was adjusted, and the law of nerve excitability was detected under two-way dual-electrode stimulation, in order to achieve selective nerve excitability, and the feasibility of two-way dual-electrode stimulation to achieve selective nerve excitatory was verified with“col ision”method. RESULTS AND CONCLUSION:The change of nerve action potential was amplified by P511 amplifier and then linked into oscil oscope for displaying, and dual-electrode stimulation waveform was the symmetric biphasic pulse with the width of 0.2 ms. With the increasing of stimulus amplitude, we achieved the selective nerve excitatory. The results indicate the selective nerve excitatory can be achieved with the closed (1 mm) dual-electrode symmetric pulse, and the feasibility and effectiveness of this method can be verified with“col ision”principle.