PURPOSE:To investigate the effect and safety of removing dental resin adhesive with ultrafast laser.METHODS:Resin adhesive layers were prepared on the surface of extracted teeth and processed with ultrafast laser scanning.Morphology was observed under optical microscope and scanning electron microscope.Component change was tested with Raman Spectrometer and dental tissue damage was observed through sample sections.RESULTS:After laser processing,resin adhesive showed significant change in colour and volume expansion along with laser parameters.Dis-lodgement happened without any external force.Carbonization was presented in Raman spectroscopy result.No obvious damage was observed in enamel underneath.CONCLUSIONS:Ultrafast laser can be used to remove dental resin adhe-sives on the enamel.

PURPOSE:To evaluate the accuracy of static guided implant placement with intraoral scanning technology and to analyze the influencing factors of guided surgery.METHODS:Totally 27 cases were included in this retrospective study. The implant designs were made in 3Shape Implant Studio and then guided implant surgeries were performed with CAD-CAM templates. Postoperative implant positions were detected with an intraoral scanner (3Shape TRIOS) and deviation of implantation was evaluated using established CAD/CAM based evaluation method. SAS 9.4 software package was used for data analysis.RESULTS:The mean deviation of entrance point and apical point was (1.182±0.609) mm and (1.658±0.741) mm, respectively. Angular deviation was (5.712±3.347)°. Implant quadrant, location of the implant site, guidance degree, supporting type and implant size influenced direction deviation, while angular deviation was mainly affected by guidance degree and number of missing teeth.CONCLUSIONS:Accuracy of static guided implant placement can be influenced by many factors. More research is needed to improve the accuracy of static guided implantation.

目的:探讨前列地尔联合丹参在防治家兔髋部骨折后下肢深静脉血栓(deep venous thrombosis,DVT)形成中的疗效.方法:将32只新西兰雌性家兔随机平均分为2组:治疗组,前列地尔+丹参组;对照组,低分子肝素组.建立家兔左侧髋部骨折模型,左下肢曲髋屈膝位石膏固定4周.分别给药持续4周,治疗组:前列地尔5μg+丹参10mL/只/天;对照组:低分子肝素钠100IU/kg/天.于术后第3、10、17、24天,2组各取4只做左下肢股静脉多普勒超声及查凝血功能,并取患肢标本做病理,观察2组药物对DVT的作用.结果:两组药物均能明显改善凝血功能指标,减轻血栓形成,差异无统计学意义(P>0.05).结论:前列地尔联合丹参防治DVT疗效显著,与低分子肝素相似,副作用小,值得临床应用.

PURPOSE:Using impact test to study cushioning and energy absorption of sports mouthguard of different thickness, material and combination.METHODS:According to the thickness, material and combination, the mouthguards were divided into 7 groups with 6 testing pieces in each group. A pendulum device was used to apply impact energy to the mouthguard and dentition model, and the magnitude of the impact energy was measured by changing the release height of the pendulum. The force sensor and the laser vibrometer were respectively connected to the data acquisition and signal analyzer to obtain the incident speed, rebound speed, maximum collision force, collision start time and collision end time of the hammer head. Collision time, energy absorption and energy absorption ratio of the mouthguard were calculated, which reflected different mouthguard cushioning and energy absorption characteristics. One-way analysis of variance and t test in SPSS 22.0 software package was used to analyze the difference between different groups.RESULTS:No matter what type of mouthguard was worn by the dentition model, the impact force was significantly reduced than without mouthguards. At the same height, there was significant difference between the average maximum collision force and the average collision time among soft mouthguards with thicknesses of 2, 3, 4, and 5 mm(P<0.05); among which the average maximum collision force of the 5 mm was the smallest and the average collision time was the shortest. There was no significant difference in the average energy absorption and the average energy absorption ratio among these 4 groups. There was significant difference in the average maximum collision force, average collision time, average energy absorption and average energy absorption ratio between the two groups of mouthguards with the same thickness of splints and different materials(P<0.05). Among them, the average maximum impact force of the 4 mm soft mouthguard was smaller and the average collision time was longer.CONCLUSIONS:Wearing sports mouthguard can reduce the risk of tooth fracture during collision. Soft mouthguard has the best cushioning performance and it is positively related to thickness. Locally strengthening hard materials can enhance energy absorption and provide better protection.

PURPOSE:To investigate the effect of tooth movement at different time after repair of alveolar bone defects with tissue engineering bone constructed by rabbit bone marrow mesenchymal stem cells (BMSCs) and beta-tricalcium phosphate (β-TCP).METHODS:Alveolar bone defect (6 mm×4 mm×8 mm) was made on the right side of 40 New Zealand rabbits, which was filled with tissue engineering bone constructed by BMSCs and β-TCP as experimental sides. Tooth extraction on the other side was performed as control. The mandibular second molars in both sides were moved mesially 2, 4, 8 and 12 weeks after surgery. The specimens were taken 4 weeks after exertion. The distance of mandibular second molar moved was measured. The periodontal tissues were observed after H-E staining. TRAP staining was performed and osteoclasts were counted in the periodontal tissues on the pressure side. BMP-2 immunohistochemical staining was used to observe the average optical density of periodontal tissue on tension side. The results were analyzed with SAS 8.0 software package.RESULTS:The distance of tooth movement, the amount of TRAP positive cells and the optical density of BMP-2 in the experimental side of the 2-week and 4-week groups were all significantly lower than those in the control side, while there was no significant difference between the 8-week and 12-week groups.CONCLUSIONS:Eight weeks after repair of alveolar bone defect with rabbit BMSCs and β-TCP is an appropriate time for orthodontic tooth movement.

目的 分析Twin-block矫治器治疗生长发育期骨性Ⅱ类错儿童的临床疗效,探讨其机制.方法 选择生长发育期骨性A类患者20例(男9例,女11例),进行Twin-block功能矫治.所有患者治疗前后拍摄X线头颅侧位片,应用Pancherz分析法测量患者治疗前后硬组织指标变化情况,同时,测量治疗前后的上气道线距变化,采用配对t检验检测治疗前后各指标差异.结果 Twin-block治疗前后,ss/OLP、pg/OLP明显增大,Co/OLP和前牙覆盖明显减小,Go-Me长度明显增加,磨牙关系明显改善,有统计学意义(P<0.05),其余各参数无统计学差异.气道测量值Adl-PNS、Ad2-PNS、Mcnamara线、U-MPW、TB-TPPW治疗后均有增大,差异有统计学意义(P<0.05).结论 Twin-block功能矫治器能有效地改善骨性A类患者的咬关系和侧貌,可以有效增加上气道各段前后径长度,这些变化主要由髁突前移导致的下颌骨生长发育所致.

PURPOSE:To explore periodontal responses on the compression side during early tooth movement into alveolar defect regenerated by bone marrow mesenchymal stem cells (BMSCs) and porous granulated beta-tricalcium phosphate（β-TCP） scaffolds.METHODS:Thirty New Zealand rabbits were used to establish bilateral mandibular defective alveolar bone model by extracting the mandibular first molars and expanding the sockets. The right mandibular alveolar defects were filled with a construct of β-TCP scaffolds combined with BMSCs as experimental group. The left alveolar defects were repaired by β-TCP scaffolds alone as control group. Eight weeks later, 6 rabbits were sacrificed to evaluate osteogenesis effect. The other rabbits were loaded orthodontic force to move the bilateral second molars forward for 4 weeks. Six rabbits in each group were sacrificed at 1, 2, 3, and 4 week after orthodontic tooth movement (OTM). The distance of OTM was measured, and the status of periodontal tissues was observed by H-E staining. The number of osteoclasts on the compression side of tooth was counted by tartrate-resistant acid phosphatase histochemistry. The results were compared between groups using SPSS 19.0 software package.RESULTS:After 8 weeks of bone grafting, the osteogenesis effect of the experimental group was better than the control group. The OTM distance in the experimental area was higher than that in the control area. At 2, 3 and 4 week of OTM, the number of osteoclasts in the experimental group was significantly higher than that in the control group.CONCLUSIONS:A tissue-engineered complex with β-TCP scaffolds and BMSCs could well repair the alveolar bone defect. When the adjacent tooth moved into regenerated area, the new periodontal tissue had an active response, promoting to accelerate tooth movement.

OBJECTIVE:This study aimed to investigate the frequency and characteristics of accessory mental foramina (AMFs) and their bony canals in a selected Chinese population using cone-beam computed tomography (CBCT). MATERIALS AND METHODS:Reconstructed CBCT images of the mandible in 784 Chinese patients (305 males and 479 females) were retrospectively analysed to identify the AMF. The presence, dimension and location of the AMF as well as the origin and course of the associated bony canal were evaluated and classified. Variations in these characteristics were analysed according to gender, side and age. RESULTS:A total of 66 AMFs were found in 57 (7.3%) of the 784 patients. The frequency of AMFs was significantly influenced by gender and side of the mandible (p < .05). Most AMFs were located apically between apices of the first and second premolars. The high-position AMFs (above the mental foramen) accounted for 54.5% of the total. The mean horizontal and vertical diameters of the AMF were 1.38 ± 0.47 and 1.23 ± 0.37 mm, respectively. Two typical types of the bony canal leading to the AMF were identified according to their bifurcation site from the mandibular canal. Most bony canals originated from the anterior loop of the mental canal (56.1%) and coursed posterosuperiorly (36.3%). The mean length of the bony canals was 5.78 ± 2.31 mm. CONCLUSIONS:This study presents a considerable frequency of AMFs in a Chinese population. The high-position AMF and the associated bony canal coursing in the oblique upward direction appear frequently. Thus, clinicians should be alert to the presence of the AMF to avoid neurovascular complications especially when dental procedures require periosteum detachment and implant insertion in the mental region.

BACKGROUND:Cone-beam computed tomography can accurately show anatomic structure of intrabony nerve canals in mandibular interforaminal region.PURPOSE:The aim was to evaluate the characteristics of intrabony nerve canals in mandibular interforaminal region by using cone-beam computed tomography (CBCT) and determine a safe zone for implant and bone harvesting.MATERIALS AND METHODS:Hemimandibles (824) CBCT images were obtained. The length of the anterior loop (AL), the length and diameter of the mandibular incisive canal (MIC) and its spatial distance in various landmarks were measured.RESULTS:The prevalence of the AL was 93.57%, and the MIC was 97.33%. The mean lengths of the anterior extension of the anterior loop (aAL), caudal extension of the anterior loop (cAL) and the MIC were 2.53 ± 1.27 mm, 6.04 ± 1.66 mm, 9.97 ± 5.15 mm, respectively. The MIC was closer to buccal border and inferior margin of mandible. The length of the AL and diameter of the MIC varied with gender.CONCLUSIONS:The safe zone recommended for implant surgery is 4 mm anterior and 8 mm inferior to the mental foramen, and 10 mm above the inferior margin of mandible. The chin bone should be harvested at least 10 mm below the tooth apices along with a limited depth of 4 mm.

Introduction We analyzed and characterized the root and canal morphologies in maxillary first and second molars in a large sample of Chinese patients using reconstructed cone-beam computed tomographic (CBCT) imaging. Methods Maxillary first (n = 1558) and second (n = 1539) molars were collected from Chinese patients (N = 844) who had undergone in vivo CBCT imaging. The root canal number and morphology were determined according to Vertucci's classification. Results A single root was found in 0.06% of first molars, which showed type I canal systems. However, second molars with a single root (4.2%) showed widely varied canal systems. The buccal roots of first molars with 2 separate roots showed type I, II, or III canal systems, whereas those of 2-rooted second molars showed widely varied canal systems. The incidence of fused roots was 1.38% for first molars and 23.9% for second molars, whereas canal fusion within fused roots was observed in 4.5% of first molars and 10.6% of second molars. Additional canals were observed in 67.8% and 29.7% of mesiobuccal roots, 1.8% and 0.7% of distobuccal roots, and 0.7% and 0.3% of palatal roots in 1523 and 1017 first and second molars with 3 separate roots, respectively. The mesiobuccal root canal number showed bilateral symmetry between 79% of first molars and 82.3% of second molars, with a concurrence rate of 59.8% between adjacent molars. Conclusions We reported the root and canal morphologic variations in maxillary first and second molars, which have not been reported for Chinese populations. Further studies should focus on canals in fused roots and mesiobuccal roots.

PURPOSE This cephalometric study was designed to evaluate the soft tissue profile effects of Twin-Block combined with straight wire appliances in the treatment of skeletal Class II malocclusion with mandibular retrognathia in growing individuals by angulation. METHODS The sample comprised 31 growing individuals with skeletal Class II and mandibular retrognathia, which were divided into 2 groups. One group (18 patients) was treated with fixed Twin-Block combined with fixed appliance， the other group (13 patients) was only treated with fixed appliance after tooth extraction. Pretreatment and posttreatment lateral cephalograms were taken before and after Twin-Block treatment and after all the fixed appliance treatment. Angular cephalometric measurements of soft tissue were analyzed statistically. Intragroup and intergroup changes of the 2 groups were evaluated by Student's t test using SPSS 15.0 software package. RESULTS Significant difference of FH-N'Pg', G-Pn-Pg', LiSi-SN and SnLs-SiLi were discovered in both groups (P<0.05). With Twin-Block combined with fixed appliance, N'-Sn-Pg', Sn-N'-Si and Si-N'-S changed significantly, while LsSn-SN and Z angle differed significantly before and after treatment with extraction and fixed appliance. After treatment of Twin-Block combined with fixed appliance, Sn-N'-Si decreased significantly, and the difference between the change of the 2 groups was significant. Meanwhile LsSn-SN was stable in combined treatment group while it decreased greatly after extraction. CONCLUSIONS Compared with extraction with fixed appliance treatment, Twin-Block combined with fixed appliance treatment is more favorable in promoting lower facial profile in growing skeletal Class II individuals with mandibular retrognathia.

Introduction: It is known that the level of the maxillary sinus floor varies with age. Because few studies have investigated whether the position of the posterior roots relative to the maxillary sinus varied with the variation of the sinus floor or not, the present study assessed the position according to age. Methods: Cone-beam computed tomographic images of 848 patients were reconstructed to evaluate the position of the posterior roots relative to the sinus floor, which were divided into 3 types, and quantify the distances between posterior root apexes and the adjacent border of the sinus floor. Measurements were taken for each root, and data were correlated with age, which was divided into 4 groups (<= 20 years, 21-40 years, 41-60 years, and >60 years). Results: A total of 3063 premolars and 3095 molars were evaluated. The mean distances from the root tips to the border of the maxillary sinus floor increased with increasing age. From the first and second premolar roots, the mean distances ranged from 3.6 +/- 4.1 mm to 8.9 +/- 4.6 mm and from 0.7 +/- 3.3 mm to 5.3 +/- 3.9 mm, respectively. From the mesiobuccal, distobuccal, and palatinal roots of the first molars, the mean distances were -0.4 +/- 2.8 mm to 4.6 +/- 4.0 mm,-0.3 +/- 2.4 mm to 4.4 +/- 3.8 mm, and -0.4 +/- 3.5 mm to 3.9 +/- 4.1 mm, respectively. From the mesiobuccal, distobuccal, and palatinal roots of the second molars, the mean distances were -0.5 +/- 2.2 mm to 3.4 +/- 3.5 mm, 0.3 +/- 2.2 mm to 3.9 +/- 3.7 mm, and 1.1 +/- 3.2 mm to 4.6 +/- 4.5 mm, respectively. The frequency of type IS decreased with increasing age. It was very low in first premolars (0%-8.13%) and higher in second premolars (0%-25.68%), first molars (0%-44.75%), and second molars (0%-32.89%). Age significantly influenced the mean distances to the sinus floor and the frequencies of type IS (inside). Conclusions: Cone-beam computed tomographic imaging is an effective method to study the position of the posterior roots to the maxillary sinus floor. Variation in proximity measurements was found by age, with those under the age of 40 showing a greater likelihood of the position of maxillary roots above/inside the sinus floor.

Purpose: Preoperative assessment of maxillary sinus anatomy can prevent complications associated with sinus grafting or implant procedures. The purpose of this study was to measure the frequency, numbers, locations, orientations, and heights of maxillary sinus septa.Materials and Methods: Reconstructed cone-beam computed tomographic images of 1,012 sinuses were analyzed using NewTom VG software (NNT 2.21, ImageWorks, Elmsford, NY). This cross-sectional study included patients who underwent radiography at the department of radiology. The presence, numbers, locations, orientations, and heights of septa were analyzed. To establish multiple predictors in this study, groups were defined according to different radiographic features of the septa. Differences between male and female groups and between edentulous and dentulous groups were tested with chi(2) tests and the level of significance was set at 5%.Results: The sample consisted of 506 patients (168 men and 338 women; average age, 35.1 yr). A significantly (P < .05) greater occurrence rate of 57.4% was observed in the edentulous group compared with the rate of 39.7% observed in the dentulous group.Conclusions: The difference in the prevalence of maxillary sinus septa between the edentulous and dentulous groups was statistically significant (P < .05), and the septa exhibited variable characteristics. It is essential and effective to analyze computed tomographic images of sinuses to evaluate the characteristics of septa before performing surgical procedures. (C) 2016 American Association of Oral and Maxillofacial Surgeons

PURPOSE To evaluate the skeletal and dentoalveolar effects of Twin-Block combined with straight wire appliances and tooth extraction in the treatment of skeletal Class II malocclusion with mandibular retrognathia in growing individuals. METHODS The sample comprised 31 growing individuals with skeletal Class II and mandibular retrognathia, divided into 2 groups. One group (18 patients) was treated with fixed Twin-block combined with fixed appliance; the other group (13 patients) was only treated with fixed appliance after tooth extraction. Lateral cephalograms pretreatment and posttreatment were taken before and after Twin-block treatment and after all fixed appliance treatment. Pancherz's cephalometric measurements were analyzed statistically. Intragroup and intergroup changes of the two groups were evaluated by test using SPSS 15.0 software package. RESULTS According to Pancherz's analysis, mandibular length increased, point Pg, mandibular incisors and first molars moved forward, maxillary incisors moved backward, overjet decreased (P<0.05) after treatment with Twin-block and fixed appliance. Within the rectification of anterior overjet, proportion of dentofacial factor was 39.5%, skeletal factor was 60.5%. Within the rectification of posterior relationship, proportion of dentofacial factor was 44.9%, skeletal factor was 55.1%. CONCLUSIONS Twin-block combined with fixed appliance treatment can efficiently promote mandibular growth, restrict forward growth of maxilla to some extent, correct incisor and molar relationship and improve skeletal profile in growing skeletal Class II individuals with mandibular retrognathia.

Objective. We examined the surface characteristics and corrosion properties of selective laser melted (SLM) cobalt-chromium (Co-Cr) dental alloys before and after porcelain-fused-to-metal (PFM) firing.Methods. Samples were manufactured utilizing SLM techniques and control specimens were fabricated using traditional casting methods. The microstructure and surface composition were examined using metallographic microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Corrosion properties were evaluated using electrochemical impedance spectroscopy. Student's t-test was used to evaluate differences in numerical results of electrochemical corrosion tests between SLM and cast specimens before or after PFM firing. The results of electrochemical corrosion tests of the SLM and cast samples before and after firing were analyzed using one-way ANOVA.Results. Although PFM firing altered the microstructure of the SLM specimens, they still exhibited a compact and homogeneous structure, and XPS analysis indicated that there were no significant differences in the surface composition of the specimens after firing. In artificial saliva at pH 5, the Rp value of the SLM specimens was 6.21 m Omega cm(-2) before firing and 2.84 ms(-2) cm(-2) after firing, suggesting there was no significant difference in electrochemical corrosion properties (P>0.05). In artificial saliva at pH 2.5, the Rp value of the SLM group was 4.80 m Omega cm(-2) before firing and 2.88 ms(-2) cm(-2) after firing, again indicating no significant difference in electrochemical corrosion properties (P>0.05). At pH 2.5, there was a significant difference in corrosion behavior between the cast and SLM groups, with the Rp value of the cast group being 0.78 m Omega cm(-2) vs. 2.88 m Omega cm(-2) for the SLM group.Significance. The improved post-firing corrosion resistance of SLM specimens provides further support for their use in prosthodontic applications, as the oral environment may become temporarily acidic following meals. (C) 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

目的:分析单纯型先天恒牙缺失患者的临床特点.方法:对48例单纯型先天恒牙缺失患者采集一般资料,根据Angle错(牙合)分类法分类,分析比较其临床特征、治疗方法和疗效.结果:本组病例中女性31例,男性17例;平均每例患者缺牙2.54颗;最常见缺失的恒牙是下颌第二前磨牙,缺失牙位多呈对称分布;临床主要表现为牙列拥挤、深覆(牙合)及深覆盖、牙列间隙等.根据Angle错(牙合)分类法分类,Ⅰ、Ⅱ和Ⅲ类分别为18、20和10例.根据缺牙数目、位置和牙列形态,结合患者要求确定相应的正畸治疗或/和修复治疗方案,疗效满意:治疗后达Ⅰ类咬合关系41例,Ⅱ类4例,Ⅲ类3例.结论:对单纯型先天性恒牙缺失患者根据其缺牙特征和分类,及时采取合理正畸及修复治疗,可达到较理想的效果.

Objective To investigate the feasibility of round-shape pin-hole marker measurement of irregular alginate dental impression deformation.Methods The metal model simulating abutment preparations was obtained,which had triangle-formed circular needles on the surface.Two types of alginate impression(Alginoplast and Palgat Plus,n=10 for each material) made by the metal model had the corresponding pin-hole markers.The dimensional changes of the markers after model withdrawl were observed by stereomicroscopy.The data of coordinates 0 min,2 min,4 min,6 min,8 min,10 min,12 min,15 min and 20 min after model withdrawl were output by the software which could simulate the center of a circle to measure the displacement and impression accuracy(additional time point of 30 min after model withdrawl for CG length recording),and the linear dimensional change rates of impression samples were calculated.Results The outline of the pin-hole marker was clear,and the values of center coordinates were well repeated.The linear dimensional change rate of Alginoplast impression samples was 0.38% 20 min after model withdrawl,and that was 0.45% for Palgat Plus impression samples.For Alginoplast impression samples,the coordinate increased by 0.040%(8.4 μm) 2 min after model withdrawl,and decreased by 0.237%(49.4 μm) 30 min after model withdrawl.For Palgat Plus impression samples,the coordinate increased by 0.068%(14.2 μm) 2 min after model withdrawl,and decreased by 0.189%(39.5 μm) 30 min after model withdrawl.Conclusion The round-shape pin-hole marker measurement of irregular alginate dental impression deformation is feasible.

PURPOSE To evaluate the clinical value of the two-phase treatment of Angle Class II division 1 malocclusion. METHODS Thirty five cases with Class II division 1 malocclusion were treated with two-phase treatment(Twin-block functional appliance and fixed appliance).Lateral cephalograms were taken before and after treatment for each patient. The results were analyzed with paired t test using SPSS11.0 software package. RESULTS After treatment ,the bite relation of molars ,the overbite and overjet and soft tissue profile were improved. ANB angle,U1-SN,OB,OJ,UL-E,ULP were decreased respectively(P<0.01). SNB, C(o)-G(o),G(o)-G(n),C(o)-G(n) were increased respectively(P<0.01). L1-Mp and FH-MP were increased, too(P<0.05). CONCLUSIONS Twin-block functional appliance possesses the orthopedic effects on Angle Class II division 1 malocclusion.It limits the maxillary growth forward and promotes the mandibular growth by repositioning the mandible forward.These may contribute to a harmonious relationship of upper and lower jaws and a better profile.

PURPOSE:To investigate the feasibility of the pin-hole marker measurement of the irregular silicone dental impression accuracy.METHODS:The metal model simulating abutment preparations had triangle-formed circular needles on the surface. Two silicone impressions were made by the metal model with the corresponding pin-hole markers. The dimensional change of the markers was evaluated by stereomicroscope. The records were output by the software which could simulate the centre of a circle to measure the displacement and dimensional accuracy.RESULTS:The outline of pin-hole marker was clear and shape was stable. Values of center coordinates were repeated well. The percentage of linear dimensional change of two impression samples was 0.023% and 0.042% at 48h respectively. Between two abutment preparations, the percentage of linear dimensional change of Zhermeck silicone impression increased 0.214% (45.1μm) at 1h and decreased 0.019% (4.0μm) at 48h while 3M silicone impression increased 0.087%(18.2μm) at 1h and decreased 0.09% (18.8μm) at 48h.CONCLUSION:The pin-hole marker measurement of the irregular silicone impression accuracy was feasible.

PURPOSE:The aim of the present study was to carry out a detailed analysis of the data on PLI, GI, SBI in fixed orthodontic patients. METHODS:375 middle school students aged 12 to 15 years old were selected as control group, including 196 boys and 179 girls. 331 patients with fixed orthodontic appliances aged 12 -15 years from city were used as experimental group, including 101 boys and 230 girls without mouth-breathing. Gingival index (GI), sulcus bleeding index (SBI), and plaque index (PLI) were recorded for each individual patient six months after being with orthodontic appliances. Four upper and four lower incisors were assessed, the data of the two groups were analyzed with SPSS 10.0 software package for Student's t test. RESULTS:It was found that there were significant higher PLI, GI and SBI values in orthodontic treated patients (P<0.01). Although there was no significantly difference in PLI value between boys and girls (P>0.05) in the experimental group, there were statistically significant higher GI and SBI values compared boys with girls (P<0.01). There were significantly higher PLI and GI values in boys' lower incisor(P<0.01). Oral health care was difficult in patients with fixed orthodontic appliances. Boys' oral hygiene was poorer than girls'. CONCLUSION:In order to maintain periodontal health, it is very important to strengthen oral hygiene to children who receive fixed appliance, especially in boys, as well as control the level of plaque accumulation in the lower incisors.