ABSTRACT
OBJECTIVE@#To investigate the effect of orthodontic traction on the microstructure of dental enamel.@*METHODS@#Forty-eight isolated premolars were randomly divided into 6 groups (=8), including Group A (blank control group), in which the teeth were bonded with the orthodontic brackets without any loading force; Groups B1, B2, and B3 where the teeth were bonded with the orthodontic brackets using clinical adhesives and loaded with 50 g force for 6 months, 200 g force for 6 months, and 200 g force for 1 month, respectively; and Groups C1 and C2, where the teeth were bonded with straight wire brackets using light curing bonding and chemical curing bonding techniques, respectively. All the teeth were embedded with non-decalcified epoxy resin. Scanning electron microscope (SEM), atomic force microscope (AFM), and energy spectrometer (EDS) were used to analyze interface morphology and elemental composition of the teeth sliced with a hard tissue microtome.@*RESULTS@#Compared with those in Group A, the teeth in the other 5 groups showed increased adhesive residue index with microcracks and void structures on the enamel surface under SEM; AFM revealed microcracks on the enamel surface with angles to the grinding direction. A larger loading force on the bracket resulted in more microcracks on the enamel interface. The interface roughness differed significantly between Groups A and C2, and the peak-to-valley distance differed significantly between Groups A, C, and C2.@*CONCLUSIONS@#Orthodontic traction can cause changes in the microstructure of normal dental enamel.
Subject(s)
Dental Enamel , Materials Testing , Orthodontic Brackets , Resin Cements , Surface Properties , TractionABSTRACT
Objective To evaluate multichannel functional electrical stimulation (FES) on motor and balance function of lower limbs in adolescent with cerebral palsy. Methods From January, 2014 to June, 2015, 20 adolescents with cerebral palsy were randomly divided into FES group (n=10) and control group (n=10). Both groups received routine exercise therapy. FES group received active and passive FES treadmill based on normal walking pattern. The Fugl-Meyer Assessment (FMA) was used to evaluate the motor function of lower limbs;the Berg Balance Scale (BBS) was used to assess the balance function, and the Gross Motor Function Measure (GMFM) was used to test the gross motor function. Results The scores of FMA, BBS and GMFM significantly improved 30 days after treatment (F>223.749, P2.706, P<0.05). Conclusion FES treatment can improve the motor and the balance function of lower limbs in adolescents with cerebral palsy.
ABSTRACT
OBJECTIVE: Different methods have been utilized to prevent enamel demineralization and other complications during orthodontic treatment. However, none of these methods can offer long-lasting and effective prevention of orthodontic complications or interventions after complications occur. Considering the photocatalytic effect of TiO2 on organic compounds, we hoped to synthesize a novel bracket with a TiO2 thin film to develop a photocatalytic antimicrobial effect. METHODS: The sol-gel dip coating method was used to prepare TiO2 thin films on ceramic bracket surfaces. Twenty groups of samples were composed according to the experimental parameters. Crystalline structure and surface morphology were characterized by X-ray diffraction and scanning electron microscopy, respectively; film thickness was examined with a surface ellipsometer. The photocatalytic properties under ultraviolet (UV) light irradiation were analyzed by evaluating the degradation ratio of methylene blue (MB) at a certain time. Antibacterial activities of selected thin films were also tested against Lactobacillus acidophilus and Candida albicans. RESULTS: Films with 5 coating layers annealed at 700℃ showed the greatest photocatalytic activity in terms of MB decomposition under UV light irradiation. TiO2 thin films with 5 coating layers annealed at 700℃ exhibited the greatest antimicrobial activity under UV-A light irradiation. CONCLUSIONS: These results provide promising guidance in prevention of demineralization by increasing antimicrobial activities of film coated brackets.
Subject(s)
Candida albicans , Ceramics , Crystallins , Dental Enamel , Esthetics , Hope , Lactobacillus acidophilus , Methods , Methylene Blue , Microscopy, Electron, Scanning , Ultraviolet Rays , X-Ray DiffractionABSTRACT
Objective To study the influence of local administration of Icariin on orthodontically induced inflammatory root resorption (OIIRR ).Methods After rat models of orthodontic root movement were successfully established,rats were injected with 200 mg/kg Icariin (Icariin group)or saline (positive control group), respectively.Left maxillary served as the negative control group.The resorption pit of root surface was measured using scanning electron microscopy (SEM), HE staining, and tartrate resistant acid phosphatase (TRAP ). Results The level of TRAP positive cells and root resorption score in Icariin group were significantly lower than those in the positive control group (P 0.05).Conclusion Local administration of Icariin may reduce the degree of orthodontically induced resorption.
ABSTRACT
BACKGROUND:TiO2-xNx film has good antibacterial effects on Streptococcus mutans, Actinomyces viscosus and Candida albicans. OBJECTIVE:To investigate the antimicrobial property of TiO2-xNx bracket. METHODS: Ten orthodontic patients were selected, and their teeth were divided into two parts by oral midline and respectively treated with ordinary metal brackets and TiO2-xNx bracket. Orthodontic plaque index, gingival index, gingival sulcus bleeding index and enamel demineralization index were detected before, and at 1, 2, 3, 4 weeks after orthodontic treatment. RESULTS AND CONCLUSION:For the ordinary metal brackets, the orthodontic plaque index, gingival index, gingival sulcus bleeding index and enamel demineralization index were al increased after orthodontic treatment (P < 0.05); for the TiO2-xNx bracket, the gingival index was increased at 3 weeks after treatment (P < 0.05), the gingival sulcus bleeding index was increased at 1, 2, 3 weeks after treatment (P < 0.05), and the enamel demineralization index was increased at 2, 3, 4 weeks after treatment (P < 0.005). Compared with the ordinary metal brackets, the orthodontic plaque index and gingival sulcus bleeding index were lower in the TiO2-xNx bracket group at 1-4 weeks after treatment (P < 0.05), and the gingival index and enamel demineralization index were lower in the TiO2-xNx bracket group at 2-4 weeks after treatment (P < 0.05). These findings indicate that the TiO2-xNx film bracket has excelent antibacterial properties, which is better to control and removal dental plaques.
ABSTRACT
Objective:To survey the relation of different vertical skeletal facial type and the third molar agenesis.Methods:The vertical face type of 207 subjects was divided into high angle(n=45),average angle(n=99)and low angle(n=63)groups by the assessments of MP-SN angle.The assessment of the third molar was made from panoramic radiographs,then the third molar agenesis rate of different vertical skeletal facial types was analysed.Chi-square criterion examination was conducted with SPSS 17.0 software. Results:In the high angle group,whether in the maxillary or mandibular,unilateral or bilateral,the absent percentage of third molar was higher than that in low angle group(P<0.05).In the females the bilateral maxillary third molar absent percentage was higher than in the males(P<0.05).The absent percentage of maxillary third molar was higher than that of the mandibular third molar(P<0.05).Conclusion:The third molar absence depends on vertical skeletal facial type.The absent percentage of third molar in the in-dividuals with high angle type is higher than that in those with low angle type(P<0.05).
ABSTRACT
BACKGROUND:In previous experiments, TiO2-xNy OBJECTIVE:To study the friction properties of orthodontic brackets coated with TiO-coated bracket has been confirmed to have excelent antibacterial properties and biological safety performance. 2-xNy METHODS: TiO film. 2-xNy film was prepared by radiofrequency magnetron sputtering on MBT bracket (0.022″). The TiO 2-x N y RESULTS AND CONCLUSION: TiO-coated brackets were analyzed by X-ray diffraction and scanning electron microscopy observations. The coefficient of static friction and coefficient of kinetic friction between the wires (0.012″, 0.014″, 0.016″) and orthodontic brackets were calculated. 2-xNy film on the bracket was of anatase structure, which was compact and had good crystalinity. Under dry condition, the coefficient of static friction and kinetic friction of the brackets coated with TiO2-xNy were less than those of ordinary brackets; under wet condition, the coefficients of static friction and kinetic friction of the brackets coated with TiO2-xNy were less than those of ordinary brackets, but the difference was not statisticaly significant. Nano-TiO2-xNy film can reduce the friction between bracket and archwire, which wil offer a novel opportunity to significantly reduce the friction during tooth movement.
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:Steam sterilization is a commonly used oral clinical method of disinfection, but whether it would produce more significant impact on equipments waiting for sterilization has been controversial. OBJECTIVE:To investigate the effect of autoclave on two kinds of orthodontic distal end cutters by comparing shearing force and corrosion after sterilization. METHODS:Tiantian (n=15) and 3M (n=15) distal end cutters commonly used in orthodontic treatment were chosen for testing and divided into three groups, respectively. Three groups for each kind of cutter were treated with high-pressure steam sterilization, steam sterilization+extraoral shear, and steam sterilization+intraoral shear, respectively. The shearing force and metal ography of the distal end cutters were recorded after 0, 20, 40, and 60 cycles of sterilization. An energy dispersive spectrometer was used to scan the surfaces of the working edges of the distal end cutters after 60 cycles. RESULTS AND CONCLUSION:It was found that with an increase in the number of sterilization cycles, the shear force and extent of corrosion increased in al six groups of distal end cutters, but the situation was worse for Tiantian cutters than for 3M cutters. It was found that the difference of shear force between the Tiantian autoclave group and 3M autoclave group was statistical y significant (P<0.05) after 20, 40, and 60 sterilization cycles. Meanwhile, the metal ography showed that different degrees of discoloration and rust spots appeared on the work edges of the two brands of distal end cutters with an increase in the number of sterilization cycles, but the corrosion of the Tiantian distal-end cutter was more widespread, and even work-edge defects appeared. The carbon content of the Tiantian distal-end cutter was higher than that of the 3M cutter (P<0.05), but the chromium content was higher in the 3M cutter (P<0.05). In addition, aluminum and titanium elements only existed in the 3M cutter. The use of the autoclave affected the distal end cutters in terms of shearing force and corrosion, but the effect on 3M distal end cutters was obviously less than that on Tiantian cutters.
ABSTRACT
BACKGROUND: Icari n as one of the main components of Epimedium has an inhibitory effect on osteoclasts.. OBJECTIVE: To further investigate the influence of icariin on the root absorption of the maxil ary first molar at mesial part during orthodontic treatment in rats. METHODS: Orthodontic root resorption models were established in the left maxil a of rats. Local injection of 200 mg/kg icari n (icari n group) or normal saline (positive control group) was administrated into the left first molar buccal periosteum. The right maxil a of rats served as negative control group that was treated with neither appliance nor drug injection. The mesial distance between bilateral first molars and the contralateral maxil ary incisor was measured before and after the appliance was placed. Mesial surface of the mesial root of bilateral maxil ary first molars was observed using scanning electron microscope. RESULTS AND CONCLUSION: Mesial movement of the maxil ary molars in the icari n group was significantly less than that in the positive control group (P < 0.05). Under the scanning electron microscope, smal absorption lacunae were scattered in the icari n group, while the positive control group showed a large amount of absorption lacunae and they were interconnected into a sheet, showing a stark contrast with the smooth root surface of the negative control group. It is indicated that icari n can inhibit root resorption caused by orthodontic treatment, while reducing the amount of mesial movement of the molar under corrective force.
ABSTRACT
<p><b>OBJECTIVE</b>To prepare a nano-TiO₂ film and characterize its antibacterial properties for dental application.</p><p><b>METHODS</b>The TiO(2-x)N(x) antibacterial film was prepared by radio frequency (RF) magnetron sputtering. The crystal structure and surface morphology of the film were characterized by X-ray diffraction, scanning electron microscopy, and EDS, and the antibacterial properties of the film against common dental pathogenic bacteria were evaluated.</p><p><b>RESULTS</b>The TiO(2-x)N(x) antibacterial film presented with an anatase phase with a mass ratio of nitrogen of 0.13% and compact and smooth surface. Antibacterial assay of the film showed a resistance rate of 97.79% against Streptococcus mutans, 49.42% against Actinomyces viscosus, and 96.84% against Candida albicans.</p><p><b>CONCLUSION</b>The nano-TiO(2-x)N(x) film shows strong antibacterial effects against common dental pathogenic bacteria and can be used as a novel antibacterial dental material.</p>