首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Benson PE  Shah AA  Campbell IF 《Journal of orthodontics》2004,31(1):41-6; discussion 16
OBJECTIVE: To investigate the effect of fluoridated elastomers on the quantity of disclosed dental plaque surrounding an orthodontic bracket in vivo. DESIGN: A randomized, prospective, longitudinal clinical trial, employing a split mouth, crossover design. SETTING: The Orthodontic Departments of Liverpool and Sheffield Dental Hospitals. SUBJECTS AND METHODS: The subjects were 30 individuals about to start fixed orthodontic treatment. The study consisted of two experimental periods of 6 weeks with a washout period between. Fluoridated elastomers were randomly assigned at the first visit to be placed around brackets on 12, 11, 33 or 22, 21, 43. Non-fluoridated elastomers were placed on the contra-lateral teeth. After 6 weeks (visit 2) the elastomers were removed, the teeth disclosed and a photograph taken. Non-fluoridated elastomers were placed on all brackets for one visit to allow for a washout period. At visit 3, fluoridated elastomers were placed on the contra-lateral teeth to visit 1. At visit 4, the procedures at visit 2 were repeated. The photographs were scanned, then the area and proportion of the buccal surface covered with disclosed plaque was measured using computerized image analysis. A mixed-effects ANOVA was carried out with the dependent variable being the area or percentage area of disclosed plaque. RESULTS: There was no evidence of a systematic error and substantial agreement for the repeat readings of the same images. The only significant independent variable for the area of disclosed plaque was the subject (p < 0.001). The significant independent variables for the proportion of disclosed plaque were the subject (p < 0.001) and the tooth type (p = 0.002). The independent variable describing the use of fluoridated or non-fluoridated elastomers was not significant for either the area or the proportion of disclosed plaque. CONCLUSION: Fluoridated elastomers do not affect the quantity of disclosed plaque around an orthodontic bracket.  相似文献   

2.
The purpose of this study was to compare the shear bond strength of orthodontic brackets bonded to teeth with either an indirect bonding technique and a new adhesive resin or a direct bonding technique and a light-activated adhesive. Fifty-four extracted premolars were mounted in acrylic blocks and randomly divided into 2 groups (n = 27). In one group, orthodontic brackets were bonded to premolars with an indirect bonding adhesive system; in the other, brackets were bonded with the direct method. Seventy-two hours later, the brackets were placed in a testing machine and subjected to a shear force with a crosshead speed of 1 mm/minute. The mean shear bond strengths for the indirect and direct groups were 11.2 and 10.9 MPa, respectively, both exceeding the minimum shear bond strength range of 5.9 to 7.8 MPa often cited in the literature for clinical success. Data were analyzed with Student t tests. No significant difference in shear bond strength between the 2 groups was detected (P =.76). Resin remnants on orthodontic bracket pads were observed with a dissecting microscope at 30x magnification and scored with a modified adhesive remnant index. There was no significant difference between groups (P >.05). There was also no correlation between shear bond strength and the percentage of adhesive resin remnants left on the orthodontic bracket. Under the conditions of this study, no evidence suggests a difference in shear bond strength of orthodontic brackets bonded to tooth enamel, whether they are bonded with the direct or indirect technique.  相似文献   

3.
This investigation was undertaken to assess bacterial plaque accumulation adjacent to orthodontic brackets. Experiments were carried out on 11 subjects who were scheduled for orthodontic treatment including extraction of two or four premolars. Metal brackets were bonded to the premolars to be extracted using macro-filled bonding composite. A conventional elastomeric ring was placed around one bracket and a steel ligature wire around the bracket on the contralateral tooth. The subjects were told to continue their normal oral hygiene regimen. Teeth were extracted at 1, 2, or 3 weeks after bracket bonding. Scanning electron microscopic (SEM) examination of brackets, excess composite, and buccal enamel revealed that mature plaque was present on excess composite at 2 and 3 weeks after bonding, whereas plaque on the gingival enamel surface was still at an early stage of development. The results demonstrate that excess composite around the bracket base is the critical site for plaque accumulation due to its rough surface and the presence of a distinct gap at the composite-enamel interface. The method of ligation does not appear to influence the bacterial morphotypes on both composite and enamel surfaces.  相似文献   

4.
The in situ caries model was used to assess the clinical benefit of fluoride-releasing elastomeric ligatures. The design of the experiment was a longitudinal, prospective, randomized, crossover clinical trial. Fourteen individuals starting orthodontic treatment with fixed appliances were recruited. Three in situ enamel specimens, with preformed subsurface carious lesions, were prepared for each patient, from human premolars. Two were placed in customized holders and one was retained as a control specimen. A crossover design was used so that patients had two experimental periods of six weeks with either fluoridated or non-fluoridated elastomerics, and a washout between. Elastomerics were randomly allocated at the first visit and one enamel specimen was placed at the beginning and collected at the end of each experimental period. The specimens were sectioned and ground to 100 microns, and transverse microradiography was carried out. They were analysed using dedicated computer software. The outcome measure was the change in the parameters of the pre-formed carious lesion, expressed as mineral loss (delta Z), lesion depth (ld), lesion width (lw), and ratio (delta Z/ld) between the three specimens. The mean mineral loss (vol %.micron) for the control specimen was 403.7 (+/- 139.5), compared with 599.3 (+/- 515.4) for the non-fluoridated ligatures and 477.2 (+/- 298.4) for the fluoridated ligatures. A one-factor within subjects ANOVA showed no statistical difference between the groups (P = 0.376). Fluoride-releasing ligatures do not provide a significant anti-cariogenic benefit in patients undergoing orthodontic treatment. This may be due to the short-term nature of the fluoride release. However, they might affect the local environment surrounding the bracket.  相似文献   

5.
INTRODUCTION: The aim of this in-vitro investigation was to determine whether stretching increases the amount of fluoride released from fluoridated elastomeric ligatures. METHODS: Ten groups of 4 fluoridated elastomeric ligatures stretched over edgewise premolar brackets were compared with 10 groups of 4 ligatures that were not stretched over brackets. Each group was placed in individual polyethylene bottles containing 1 mL of distilled water and maintained at 37 degrees C in an incubator. A polyethylene bottle containing only distilled water and 4 brackets was used as the control. The fluoride content of the samples was determined once a day for 7 days and regularly thereafter up to 196 days. A fluoride-ion selective electrode coupled to an analyzer was used to determine the fluoride content of the solutions. The sample solutions were changed 24 hours before readings to prevent the results from being cumulative. RESULTS: The fluoride-ion release for each of the groups was calculated and expressed as total fluoride release in micrograms of fluoride per day per milliliter per elastomer. During the first month in solution, the stretched fluoridated elastomers released approximately 32 microgF.day/mL and the unstretched speciments released 30 microgF.day/mL. This represents a 7% increase in fluoride release, which was statistically significant (P = .007). Over the entire test period (196 days), the modules stretched over the brackets released about 13% more fluoride. This was also a statistically significant difference (P = .001). CONCLUSIONS: Stretching increases the concentration and amount of fluoride released from fluoridated elastomeric ligatures.  相似文献   

6.
Because the risk of dental caries increases with the use of orthodontic appliances and its control cannot depend only on the patient's self-care, this study evaluated the effect of a glass ionomer cement on reducing enamel demineralization around orthodontic brackets. Fourteen orthodontic patients were randomly divided into 2 groups of 7; they received 23 brackets fitted to their premolars, bonded with either Concise (3M Dental Products, St Paul, Minn), a composite resin (control group), or Fuji Ortho LC (GC America, Chicago, Ill), a resin-modified glass ionomer cement (experimental group). The volunteers lived in a city that has fluoridated water, but they did not use fluoridated dentifrices during the study. After 30 days, the teeth were extracted and longitudinally sectioned; in the enamel around the brackets, demineralization was assessed by cross-sectional microhardness. The determinations were made at the bracket edge cementing limits, and at occlusal and cervical points 100 and 200 microm away from them. In all of these positions, indentations were made at depths from 10 to 90 microm from enamel surface. Analysis of variance showed statistically significant effects for position, material, depth, and their interactions (P<.05). The Tukey test showed that the glass ionomer cement was statistically more efficient than the control, reducing enamel demineralization in all analyses (P<.05). The use of glass ionomer cement for bonding can be encouraged because it decreases the development of caries around orthodontic brackets.  相似文献   

7.
正畸粘接用玻璃离子粘固剂的抑菌性能研究   总被引:2,自引:0,他引:2  
目的 探讨正畸粘接用玻璃离子粘固剂对托槽周围菌斑中致龋菌是否有抑制作用。方法 选择 2 2例患者 ,采用自身对照方法 ,分别用玻璃离子粘固剂和复合树脂粘接剂粘接托槽 ,1个月后采集托槽周围菌斑 ,进行细菌培养和微生物分析。结果  2种粘接剂托槽周围菌斑的总菌落形成单位数 (cloneformingunit ,CFU)差异无显著性 (复合树脂粘接剂为 2 4× 10 10 CFU/L ,玻璃离子粘固剂为 2 8× 10 10 CFU/L ,P =0 6 73)。与复合树脂粘接剂相比 ,应用玻璃离子粘固剂后并未明显减少托槽周围菌斑中变形链球菌的数量和百分比。结论 正畸粘接用玻璃离子粘固剂不能在较长时间内有效抑制托槽周围致龋菌的生长繁殖  相似文献   

8.
Abstract: Objectives: This study was performed to detect the opportunistic bacteria and fungi from the oral cavities of orthodontic patients and examine the ability of the organisms to adhere to saliva‐coated metallic brackets. Methods: Opportunistic bacteria and fungi were isolated from 58 patients (orthodontic group: 42; non‐orthodontic group: 16) using culture methods and were identified based on their biochemical and enzymatic profiles. Seven opportunistic and four streptococcal strains were tested for their ability to adhere to saliva‐coated metallic brackets. Results: More opportunistic bacteria and fungi were detected in the orthodontic group than in the non‐orthodontic group (P < 0.05). Opportunistic bacteria adhered to saliva‐coated metallic brackets to the same degree as oral streptococci. Conclusions: The isolation frequencies of opportunistic bacteria and fungi increase during orthodontic treatment, suggesting the importance of paying special attention to oral hygiene in orthodontic patients to prevent periodontal disease and the aggravation of systemic disease in immunocompromised conditions.  相似文献   

9.
PURPOSE: Tooth-brushing and fluoride dentifrice use are the primary oral health activities for young children. Fluoridated dentifrice has had an important impact on the reduction in children's caries lesion rates, but no studies have focused on patterns of use at multiple time points early in life. The purpose of this paper is to describe tooth-brushing and fluoride dentifrice use in a cohort of children from ages 6 to 60 months. METHODS: The data are from the Iowa Fluoride Study, a longitudinal investigation of fluoride intake from birth. Questionnaires assessed tooth-brushing patterns and fluoride dentifrice use at age 6 months, and at 3-, 4-, or 6-month intervals thereafter. RESULTS: At 6 months of age, 28% of the children's teeth were brushed or cleaned, and 3% of these used fluoridated dentifrice, increasing to 95% at 20 months (83% of them with fluoridated dentifrice). Use of dentifrice flavored for children increased from 40% of those brushing at 9 months to 71% at 60 months. From 9 to 32 months, about 55% of the children were using approximately the recommended amount of dentifrice. However, the percentage using more than recommended increased from 12% at 9 months to 64% at 60 months. Mothers placed the dentifrice on the toothbrush 85% of the time at 9 months, 81% at 20 months, 49% at 36 months, and 31% at 60 months. CONCLUSIONS: By age 2, almost all children were brushing with fluoridated dentifrice, but less than half brushed twice a day, even at age 5. Mothers played the most important role in the children's home care habits.  相似文献   

10.
This study evaluated the effect of sustained-release chlorhexidine varnish on orthodontic patients. Ten children, ages 10 to 16 years, participated. Bacterial levels of Streptococcus mutans and Actinomyces viscosus and total counts were evaluated in sputum samples. These counts were evaluated at 4 stages: before orthodontic treatment, at least 2 weeks after bonding of the brackets, 1 week after application of chlorhexidine varnish, and 3 weeks after application of chlorhexidine varnish. Increases in bacterial levels of S mutans and in the total bacterial count were detected after the brackets were bonded. One week after the sustained-release chlorhexidine varnish was applied, a significant decrease of total bacterial levels and S mutans was observed. This decrease persisted for 3 weeks after the first application. No significant change in A viscosus levels occurred during that period. The results provide additional evidence that sustained-release chlorhexidine varnish decreases S mutans levels in orthodontic patients with fixed appliances and therefore might be useful in preventing caries lesions.  相似文献   

11.
Abstract — Previous studies have shown that tetracyclines react with enamel and dentin in vitro to form slightly soluble compounds wish a pronounced and long-lasting antimicrobial capacity. The purpose of the present project was to study the effect of doxycycline-impregnation of dentin on the growth of oral microorganisms in vivo. Slabs of native human dentin were immersed in aqueous solutions of doxycycline HC1, 10 mg/ml, for 10 min, and were subsequently ligated to orthodontic brackets placed bucally on maxillary molars in seven individuals. Untreated native dentin specimens were similarly placed on contralateral teeth. Test and control specimens were removed from the oral cavity after 2 h, 24 h or 120 h, respectively. The individual specimens were then placed in 0.5-ml saline and agitated mechanically for 30 s. The resulting bacterial suspensions were plated onto blood agar and various selective growth media. Based on CFUcounts obtained after incubation of the plates, doxycycline-treated dentin specimens showed a significantly lower number of viable microorganisms after 2 h and 24 h in the oral cavity than did the control specimens. The bacterial growth was also less pronounced in the test specimens after 120 h. The effect of doxycycline was similar for all the cultivable bacteria. No significant difference in yeast growth was seen between test and control specimens.  相似文献   

12.
Commercially available light-emitting diode (LED) light-curing units recently have been introduced to the dental products market. No published studies have evaluated the adequacy of cure of commercially available LEDs. The purpose of this study was to compare the shear bond strength of orthodontic brackets bonded to teeth with conventional halogen-based light-curing units and commercially available LED curing units. Two LED light-curing units (LumaCure and VersaLux) and 2 halogen-based light-curing units (Optilux 501 and ProLite) were tested. One hundred standard metal orthodontic brackets were bonded to extracted human third molars with a light-cured adhesive system. The specimens were divided into 4 groups of 25 teeth each. In each group, the brackets were cured for 40 seconds with a different light-curing unit. The specimens were stored in water at 37 degrees C for 24 hours and then tested in shear with an Instron universal testing machine at a crosshead speed of 1 mm/min until the brackets debonded. One-way analysis of variance detected no differences in bond strength between the 4 groups (P =.78). Chi-square analysis detected no difference in the adhesive remnant index scores of the 4 groups (P =.89). Under the conditions of this study, the LED light-curing units bonded brackets to etched tooth enamel as well as the halogen-based light-curing units. Additional clinical studies are necessary before routine use of commercial LED light-curing units can be recommended.  相似文献   

13.
OBJECTIVES: The two objectives of this experiment were to determine the surface temperature of enamel following acid etching, rinsing and drying, and to see whether two commercially available orthodontic brackets could be bonded to enamel using an anaerobic adhesive. METHODS: Enamel surface temperature was determined in vivo using a surface temperature probe on a total of 60 patients. Stainless steel orthodontic brackets were bonded to human enamel using an anaerobic adhesive and a control orthodontic adhesive. The enamel was etched prior to bonding either with a solution of 37% o-phosphoric acid or, in the case of the anaerobic adhesive specimens, with a solution of 37% o-phosphoric acid containing copper (II) chloride. After bench curing the specimens were shear bond tested to failure and the load at debond recorded in each case. RESULTS: The bond test results were analyzed using median force to debond (N) and 95% confidence intervals, Kaplan-Meier survival probabilities and log-rank tests. CONCLUSIONS: After etching rinsing and drying the enamel surface temperature ranged from 21.54 to 24.19 degrees C, which is within the range suitable for anaerobic adhesive use. Bond testing to failure demonstrated that bracket base design affected the measured force to debond with both the anaerobic adhesive under test and the control adhesive. In addition, the anaerobic adhesive was affected by the material composition of the bracket base and curing time. After 1h of curing and using the Miniature Twin bracket, the measured force to debond exceeded the 10 min force to debond results of the control adhesive. SIGNIFICANCE: It is possible to bond commercially available orthodontic brackets to teeth using an anaerobic adhesive.  相似文献   

14.
The aim of this study was to manufacture and test, in vitro, a novel modification to provide fluoride-releasing orthodontic brackets. Thirty-two orthodontic brackets were drilled to produce a recess (approximately 1.3 mm in diameter and 0.7 mm in depth) at the centre of the bracket base. Four materials, with and without the addition of sodium fluoride, a glass ionomer cement (Ketac Cem micro), a resin-modified glass ionomer cement (RMGIC; GC Fuji Ortho LC), a zinc phosphate (Zinc Cement Improved), and a resin (Transbond XT) were used to fill the recess in the bracket base. Fluoride release was measured daily during the first week and then weekly for 10 weeks. An ion chromatograph with suppressed conductivity was used for free fluoride ion determination. Statistical analysis to determine the amount of flouride release was undertaken using analysis of variance and Tukey's test. During the first 2 weeks, the resin group, with the addition of 38 per cent sodium fluoride added, released significantly more free fluoride (P < 0.05), but after 2 weeks the fluoride release markedly decreased. After 5 weeks, the RMGIC group, with 15 per cent added sodium fluoride, had significantly higher (P < 0.05) daily fluoride release than the other groups. The findings demonstrated that an appropriate fluoridated material can be used as a fluoride-releasing reservoir in a modified orthodontic bracket to enable it to release fluoride over the period of fixed appliance treatment.  相似文献   

15.
Argon lasers, due to their significant time savings over conventional curing lights, are being investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel. The purpose of this study was to evaluate the effects of argon laser irradiation on bond strength at 3 different laser energies (200, 230, and 300 mW) and at 3 unique time points of laser application (before, during, or after bracket placement). One hundred-fifty human posterior teeth were divided into 9 study groups and 1 control group. After debonding, the adhesive remnant index was scored for each tooth. There was no evidence of an effect of energy level on bond strength, P =.903, or of an interaction between timing of bracket placement and energy level, P =.858. When combining data across energy levels, the mean bond strength was significantly different between all 3 bracket placement groups, P <.001. In addition, the mean bond strength of teeth lased after bonding was significantly higher than the control group, P <.05. There were no statistically significant differences between adhesive remnant index scores among the 10 groups. Lasing the enamel before or after bonding does not adversely affect bond strength. Use of the argon laser to bond orthodontic brackets can yield excellent bond strengths in significantly less time than conventional curing lights, while possibly making the enamel more resistant to demineralization.  相似文献   

16.
One problem clinicians face during treatment is bracket failure. In a busy orthodontic practice, a significant number of teeth will need to be rebonded. The purpose of this study was to evaluate the effect of repeated bonding with 2 different adhesives, a composite and a cyanoacrylate, on the shear bond strength of orthodontic brackets. Thirty-one freshly extracted human molars were collected. Brackets were bonded with 1 of the orthodontic adhesives according to the manufacturer's instructions. In group I, the teeth were etched with 37% phosphoric acid, a sealant was applied, and the brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif) and light cured for 20 seconds. In group II, the teeth were etched with 35% phosphoric acid, and the brackets were bonded with SmartBond (Gestenco International, G?thenburg, Sweden). In each group, the teeth were bonded and debonded 3 times with the same adhesive. At each sequence, the brackets were removed within 30 minutes after bonding to simulate the clinical condition at which a newly bonded bracket is tied to the archwire. Student t tests and the analysis of variance repeated measure were used to compare the shear bond strength between adhesives and within each adhesive at different debonding sequences. The results indicated that, at the first debonding sequence, the 2 adhesives did not have significantly different shear bond strengths. Between debonding sequence 1 and 2, there was a significant (P 相似文献   

17.
AIM: The aim of the present study was to investigate changes in the subgingival flora in adults with chronic periodontitis undergoing orthodontic fixed appliance therapy. PATIENTS AND METHODS: In seven adult patients who had undergone nonantibiotic periodontal pretreatment, the subgingival bacteria were subjected to microbiological examination and the number of periodontopathogenic organisms was determined before (T1: prior to treatment being started), during (T2: 6 weeks after orthodontic treatment was started) and after the end of orthodontic treatment (T3: 6 weeks after removal of the fixed appliances). RESULTS AND CONCLUSION: During the fixed appliance therapy (metal brackets, NiTi archwires, stainless steel archwires), a marked reduction was observed in the total bacteria count from the subgingival pocket despite the clinical periodontal parameters remaining almost unchanged. However, the total count of some highly pathogenic bacteria rose again slightly after the end of treatment. We attribute the marked improvement in the periodontopathogenic bacteria spectrum under fixed appliance therapy with metal brackets, NiTi archwires and stainless steel archwires to metal corrosion entailing the release of primarily nickel ions, which have a toxic effect on bacteria and thus enable the regeneration of the physiological bacterial flora. In none of the patients was a deterioration of the periodontal status observed during and after fixed appliance therapy.  相似文献   

18.
《Journal of orthodontics》2013,40(3):243-245
Abstract

At the commencement of fixed appliance therapy the operator has the choice of either placing bands, brackets, and archwires at one visit, and hence loading the brackets within an hour of initial placement, or placing the brackets and separators at one visit, and the bands and archwires at a subsequent visit. In the case of the latter, the brackets will only be loaded intermittently during the intervening period, for example during mastication. The present study investigated the effect of loading bonded brackets for 2 weeks prior to measuring shear debonding force in vitro, and compared the results with in vivo bond failure rates for two groups of patients whose brackets were loaded by the archwire either immediately after bonding, or not less than 1 week later. Shear testing and survival analysis indicated in vitro loading prior to testing had no significant effect on the shear debonding force. When the in vivo data were studied there was no significant difference in the rate of bond failure between those patients whose archwires were placed at the time of fitting the appliance, and those whose archwires were placed no less then 1 week after bracket placement.  相似文献   

19.
Influence of self-etchant application time on bracket shear bond strength   总被引:2,自引:0,他引:2  
OBJECTIVE: To determine the influence of self-etching primer (SEP) application time on the shear bond strength of orthodontic brackets. MATERIALS AND METHODS: Forty human molars were cleaned, mounted, and randomly divided into two groups. The same SEP, adhesive, and brackets were used in both groups. Twenty teeth were conditioned following the manufacturers' recommendations by rubbing the SEP on the enamel surface for 3 to 5 seconds. The remaining 20 teeth were conditioned using the same SEP, but the application time was increased to 15 seconds. The teeth were debonded within half an hour following initial bonding using a universal testing machine. After debonding, the amount of residual adhesive remaining on the tooth was determined. Student's t-test was used to compare the shear bond strength (SBS) of the two groups, and the chi2 test was used to compare the Adhesive Remnant Index (ARI) scores for the two adhesive systems. RESULTS: The mean SBS of the brackets bonded to the teeth subjected to the SEP for 3 to 5 seconds was 8.0+/-4.6 MPa and was not significantly different (t=-0.69, P=.494) from the SBS of the brackets bonded using a 15-second SEP application time (x=8.9+/-3.4 MPa). The comparisons of the ARI scores between the two groups (chi2=2.16) indicated that bracket failure mode was not significantly different (P=.340) for both groups, and most failures were at the bracket-adhesive interface. CONCLUSION: The present findings indicate that increasing the SEP application from 3 to 5 seconds to 15 seconds does not result in a significant increase in SBS.  相似文献   

20.
This article describes the complex dental treatment of an adult patient with multiple missing teeth, mild periodontitis, and a malocclusion. Titanium implants were placed in the posterior mandibular edentulous segments and became osseointegrated. The placement of the mandibular implants was originally designed for orthodontic anchorage. The mandibular implants would subsequently be used for implant-retained crowns on completion of orthodontic treatment. After a 4-month healing period, an impression was made of the implant hexes and a master cast was formed. Two-piece temporary healing abutments were placed on the implants and used to retain orthodontic brackets. The orthodontist retracted the mandibular anterior teeth using the posterior implants for anchorage. The abutment screws of the 2-piece temporary healing abutments were tightened to 20 N-cm at the insertion appointment and did not need to be tightened again during the course of orthodontic therapy. Standard orthodontic brackets were cemented to the 2-piece temporary healing abutments. Orthodontic treatment was accomplished uneventfully. Prosthodontic treatment was completed using the osseointegrated implants to replace the missing teeth. The methods described in this clinical report present clinicians with additional choices in the treatment of complex dental disease using osseointegrated dental implants.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号