Expert consensus on pediatric orthodontic therapies of malocclusions in children

Malocclusion,identified by the World Health Organization(WHO)as one of three major oral diseases,profoundly impacts the dental-maxillofacial functions,facial esthetics,and long-term development of~260 million children in China.Beyond its physical manifestations,malocclusion also significantly influences the psycho-social well-being of these children.Timely intervention in malocclusion can foster an environment conducive to dental-maxillofacial development and substantially decrease the incidence of malocclusion or reduce the severity and complexity of malocclusion in the permanent dentition,by mitigating the negative impact of abnormal environmental influences on the growth.Early orthodontic treatment encompasses accurate identification and treatment of dental and maxillofacial morphological and functional abnormalities during various stages of dental-maxillofacial development,ranging from fetal stages to the early permanent dentition phase.From an economic and societal standpoint,the urgency for effective early orthodontic treatments for malocclusions in childhood cannot be overstated,underlining its profound practical and social importance.This consensus paper discusses the characteristics and the detrimental effects of malocclusion in children,emphasizing critical need for early treatment.It elaborates on corresponding core principles and fundamental approaches in early orthodontics,proposing comprehensive guidance for preventive and interceptive orthodontic treatment,serving as a reference for clinicians engaged in early orthodontic treatment.

Effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats

Objective:To investigate effect of orthodontic force on inflammatory periodontal tissue remodeling and expression of IL-6 and IL-8 in rats.Methods:Eighty SD rats were randomly divided into 4 groups,blank control group(group A)with 5 rats,treatment normal group(group B)with 25 rats,inflammation control group(group(group C)with 25 rats,inflammation treatment group(group D)with 25 rats.Immunohistochemistry and histomorphometric analysis was performed to measure the expression of IL-6,IL-8 and the firet molar to the recent movement in the distance.Results:The expression of IL-8 reached a maximum on day 5 and declined thereafter in group B;the expression of IL-6 reached a maximum on day 5 in group B.The expression of IL-6 and IL-8 was gradually weakened with time in group C.The expression of IL-6 and IL-8 were high,and reached a maximum on day 5 and declined thereafter in group D.AD of positive cells in group D were higher than group B at each time point(P<0.05).The time which 0.49 N orthodontic force was loaded was longer,orthodontic tooth movement distance was greater.Movement distance in group D were longer than group B(P<0.05).Conclusions:Orthodontic force as well as inflammatory stimulus can evoke the expression of IL-6 and IL-8.Under the combined effects of inflammation and orthodontic force,the expression of IL-6,IL-8will increase.

颌面部爆炸伤后外形修复实验研究(英文)

Objective To study the characteristics and the way of reconstruction in maxillofacial explosive wound.Methods30dogs were randomly divided into 6groups and th e maxillofacial region were wounded by smoothbore barrels combined with detonators.Histological changes of soft tissue at different distance from wound track were observed after injury.At 72h post injury,5dogs in o ne group were re-debrided and reconstructed.Results At 72h after wound,the soft tissue in jury was the most serious.Muscles at 0～0.8cm distant to the wound track we re completely necrotized.The vibration area spread beyond 1.6cm.The wounds were well healed.Conclusions The explosive injury of max-illofacial region was characterize d by wide range of injury and heavily c ontamination.The reconstruction o f soft tissue defect by vascularized gracilis flaps was effective.

Distalization of maxillary molars for Class Ⅱ malocclusion with Chinese Ni-Ti coil-springs appliance

Objective: To evaluate the effects of the Chinese Ni-Ti coil-springs appliance on distalization of maxillary molars and the reciprocal effects on the anchorage teeth. Methods:Twenty-four adolescent patients(12 boys,12 girls) with Class Ⅱ malocclusion were selected and the coil-springs appliance was used during the treatment. Pre- and postdistalization lateral cephalometric radiographs were analyzed and compared. Results: The average time for the correction of Class Ⅱ molar relationship was 4.6 months. And the mean distance of molar distalization was 4.4 mm. The Chinese Ni-Ti coil-springs also demostrated less tipping and better bodily movement of maxillary molars. Conclusion: This study suggests that the Chinese Ni-Ti coil-springs appliance distalizes the upper molar significantly, while there is no remarkable loss of anchorage because of patients’ wearing headgear with J hooks at night and Class Ⅱ elastics in the day time.

Effect of the cyclic stretch and role of related signal pathway on the osteogenic differentiation of MC3T3-E1 cells

Mechanical strain stimulation is one of the important factors to regulate bone metabolism,maintain bone mass and bone structure.In the process of osteoblasts response to the mechanical strain stimulation,the signal transduction pathways were activated by mechanical stimulation Extracellular signal regulated kinase 1/2(ERK1/2)and Nuclear factor kappa B(NF-κB)signal pathways are both important in the process of signal transduction in osteoblasts.They played an important role in differentiation of osteogenic progenitor cells.Therefore in this research we cultured MC3T3-E1 osteoblasts,and established the vitro model of the mechanical strain stimulation,to observe the differentiation of MC3T3-E1 osteoblastic cells and investigate the interac-

Comparative Evaluation of the Implant Made of Yttrium-partially Stabilized Zirconia and Pure Titanium on Stress Distribution by Anisotropic Finite Element Method

The purpose of this research is to analyze and compare stress distribution patterns around dental implant made of pure titanium and yttrium-partial stabilized zirconia （YPSZ） in anisotropic versus isotropic finite element method under vertical and oblique loads. Although the properties of implant and crown were changed, similar stress distribution and close stress level were observed in two different implant finite element models. The stress values were a little lower in the YPSZ model. In the bone, anisotropy increased the stress values by 30%- 70% in the isotropic cases. The YPSZ implant could be more valuable choice for implant because of esthetic requirement. Anisotropy had subtle, yet significant effects on the stress level.

A study of the rotation rate of single-rooted teeth in dogs

Sixteen one-year-old dogs were used in our experiment.We rotated the maxillary secondincisors of the dogs,applying a force of 100g and a moment of 550g·mm.The duration of theexperiment varied from 72h to 8 weeks.Activation was performed once every 2 weeks and the impressions were taken in order to measure the angles of rotation.The results of our experiment showthat the rotation rate of single-rooted tooth in dogs is 3.04/week.The graph shows the form ofgradual stairs.This paper introduces a new specialized experimental apparatus for tooth rotation.The angles of rotation are measured geometrically.

Temporary Cavity Effects of High Velocity Spherical Steel Bullet Wounds in Maxillofacial Region of Dogs

Maxillofacial region wounds of dogs were inflicted by spherical steel bullets,0.7 g weight,with the muzzle velocity of 1.3 km/s.The photographs of the temporarycavity were taken with a high speed x-ray cine-camera,and local wounding conditionswere observed with the naked eye.The experimental results proved that a temporary ca-vity was formed in the maxillofacial region wound.The contusion zone of the maxillofa-cial soft tissue was smaller than that of the extremities.The contusion zone of the skinand oral mucous membrane was 1-2 mm,and that of muscle was 5-8 mm in thickness.In clinical situation,the tissues of the contusion zones should always be excised since itconsists of devitalized tissue.The temporary cavitation is an important factor in causingstructural injuries of tissues around the local wound track.

Effects of tooth rotation on neighboring teeth and periodontal tissues

In the present experiment,we investigate the effects of orthodontic tooth rotation onneighboring teeth and periodontal tissues.The second maxillary incisors of 16 randomly selecteddogs were subjected to rotation at a magnitude of 100 grams and a moment of 550 g·mm in a du-ration of 3 to 56 days.Then sections were prepared for histological examination.The findings re-vealed that,due to tooth rotation,neighboring teeth were drifted and rotated(82%),and therewere disarrangement and hyalinization of the periodontal ligament(88%),remodeling of the pe-riodontium(86%)and root resorption(32%)were also observed.These results demonstratethat tooth rotation may exert marked effects on neighboring teeth and periodontal tissues,whichmay be of important clinical significance.

Effect evaluation of artemisia desertorum spreng on ability of daily life after extraction of impacted tooth

AIM:To investigate the effect of locally used Shahaosan on preventing the complication of extraction of impacted tooth.METHODS:274 cases patients with extraction of impacted teeth were randomly devided into 3 groups named A,B and C.Shahaosan and Yunnan white drug were processed into drug A and B by department of pharmacy with the same color, shape and quality which are blind to doctors and patients.When the impacted teeth were extracted, administed group A(92 cases) with drug A,group B(86 cases) with drug B and group C(96 cases ) was a blank control. After the operation,incidence and severe intensity of dry socket in each group were observed and evaluated by scores.RESULTS:The incidence of dry socket in group A,B and C were 0.09%(1/92),2.32%(2/86),8.33%(8/96).There was no significant difference between group A and B, group B and C, while a significant difference showed between group A and C.The PoSSe score in group A, B and C was 19.36,27.80 and 22.83 respectively.Afer the experiment the department of pharmacy informed that drug A is Shahaosan and drug B is Yunnan white drug.CONCLUSTON:Compiments of dry socket induced by extracting of lower jaw impacted teeth can be prevented by locally administered with Shahaosan, but no significant effect of alleviating the symptom of dental extraction.

Low Temperature Degradation of Alumina-toughened Zirconia in Artificial Saliva

The long-term aging behavior of an alumina-toughened zirconia （ATZ） ceramic in artificial saliva hydrothermal atmosphere was determined and compared with that of tetragonal zirconia polycrystals doped with 3mo1% Y203 （3Y-TZP）. The specimens of 3Y-TZP and ATZ were aged in distilled water and artificial salivary respectively at 134 ~C. Monoclinic phase content was evaluated by X-ray diffraction （XRD） analysis. Specimen strength was determined by a biaxial bending test. Surface screening was done using an atomic force microscope （AFM）. No statistically significant influence of any treatment on strength was demonstrated for either material. However, XRD measurements revealed ATZ＇s anti-aging properties were much better than TZP after the aging treatment. Therefore, ATZ can be applied to the field of dentistry. Artificial saliva in ceramic surface sediments may be useful for stren^heninl ceramics.

The Effects of Dense/Nanometer Hydroxyapatite on Proliferation and Osteogenetic Differentiation of Periodontal Ligament Cells

The objective of this study is to investigate possible effects of nanometer powder of hydroxyapatite on proliferation of periodontal ligament cells. With sol-gel method, the nanometer hydroxyapatite powder were fabricated. The primary periodontal ligcament cells were caltured on dense particle hydroxyapatite and nanometer particle hydroxyapatite. The effects on proliferation of periodontal ligament cell were examined in vitro with MTT （ methyl thiazolil tetracolium） test. The intercellalar effects were observed with scanning electron microscopy and energy dispersive X-ray analyzer. In addition, the influence of two materials on osteogenetic differentiation was determined with measurement of ALP （ alkaline phosphatase ） activity. It is concluded that nanometer hydroxyapatite can promote proliferation and osteogenetic differeraiation of periodontal ligament cells and it may become absorbable agent in osseous restoration.

Isolation of cardiac conduction system of rat heart by laser capture microdissection

Objective：To isolate ceils of cardiac conduction system （CCS） with laser capture microdissec tion （LCM） and extract and evaluate quality of small amount of RNA from ceils of CCS. Methods： Cryo star sections were followed by H-E staining. 20 pieces of H-E stained eryostat sections were scraped and its RNA was assessed to insure that RNA didn＇t degrade in dyeing and dehydration process. Ceils of CCS were captured with LCM and quality of small amount of RNA was verified with RT-PCR. Results： Ceils of CCS isolated with LCM had clear morphology after staining. High quality RNA was extracted from LCM samples and scraped tissues; 18S rRNA and 28S rRNA were seen distinctly on gel eleetrophoresis. Low level of small amount of RNA extracted from LCM sample was below the limit of detection on gel eleetrophoresis or ultraviolet speetrophotometer. The housekeeping genes β-aetin and GAPDH were successfully amplified with small amount of RNA. Conclusion ：This study resolves the problem of acquiring material of CCS precisely that hinders gene research of CCS. It is found out that the method is easy and reliable to extract and assess the quality of small amount of RNA from mierodisseeted ceils of CCS.

Feasible rehabilitation training on pa-tients after incision of fibula

BACKGROUND: Systematic and progressive rehabilitation exercises play important roles in accelerating the course of rehabilitation of patients with defection of mandibulla which is recovered with free fibula.OBJECTIVE: To investigate the effect of rehabilitation training on patients after incision of fibula.UNIT: Department of Oral and Maxillofacial Surgery, Stomatology Medical College of Fourth Military Medical

The effect of Nifedipine on the expression of type I collagen in gingival fibroblasts

Objective：To investigate the effect of nifedipine（calciumchannel blocker） on the expression of collagen in gingival fibroblasts invitro. Methods：Primarily gingival fibroblasts were cultured and incubated with various concentrations of nifedipine（108 μg/L, 360 μg/L and 1200 μg/L）for 5 days. Gingival fibroblasts were primarily cultured derived from nifedipine responders and nonresponders in the presence of 360 μg/L nifedipine. Enzyme-linked immunosorbent assay was used to evaluate the amount of type I collagen. Cell proliferation was measured by cell counting with evaluating MTT value. Results：The expressions of collagen and cell proliferation were significantly different among the high concentration groups and the others on the fifth day, especially higher in 360 μg/L and 1200 μg/L groups and also different among nifedipine responders and non-responders. Conclusion：The expression of collagen and cell proliferation may be concerned with the biological mechanism for gingival overgrowth.

Effects of secretive bone morphogenetic protein 2 induced by gene transfection on the biological changes of NIH3T3 cells

Background Bone morphogenetic proteins （BMPs）, which belong to the transforming growth factor beta superfamily, are powerful regulators of cartilage and bone formation. This study investigated the biological changes of NIH3T3 ceils incubated with secretive BMP2 that was induced by gene transfection through transwell.Methods Eukaryonic expression vector （pcDNA3. 1-B2 ） was transfered into NIH333 cells with Sofast^TM, a positive compound transfection agent. The positive cell clones were selected with G418. The cytoplasmic and extracellular expressions of BMP2 were determined by immunohistochemical stain and enzyme-linked immunosorbent assay. NIH333 ceils were co-cultured with hBMP2 gene transfecting ceils through transwell, and the ultrastructure, alkaline phosphatase activity and the expression of osteocalcin （the marker of osteogenetic differentiation） changes were observed.Results There were cytoplasmic and extracellular expressions of BMP2 in transfecting NIH3T3 ceils. The ultrastructural changes, the high activity of alkaline phosphatase and the positive stain of osteocalcin suggested the osteogenetic differentiation tendency of NIH3T3 cells co-cultured with transfecting NIH3T3 cells.Conclusion Secretive BMP2 that is induced by gene transfection could promote the osteogenetic differentiation of fibroblast ceils.

Compositional change in human enamel irradiated with MIR free electron laser

The purpose of this study was to investigate compositional changes in human enamel irradiated with the free electron laser (FEL). The exposure on dental enamel at the wavelength of 9.64 μm was observed with the Beijing free electron laser. The distribution of elements in the irradiated or non-irradiated enamel was measured by scanning electron microscope (SEM) with energy-dispersive spectroscopy and synchrotron radiation X-ray fluorescence (SRXRF) in Beijing Synchrotron Radiation Facility (BSRF). The results showed that the P/Ca ratio in the ablation region of enamel at the maximum wavelength of infrared absorption was obviously smaller than that at the non-maximum wavelength. In the ablation region the ratios of P/Ca and Ca/Sr were smaller than those in the non-ablation region. The distributions of P, Ca and Sr in the ablation region were heterogeneous due to the element change caused by FEL irradiation.