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25 April 2018, Volume 27 Issue 2 Previous Issue    Next Issue

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Re-evaluating the clinical implications of clear aligners and lingual appliances - a retrospective and prospective overview SHEN Gang 2018, 27 (2):  113-116.  doi: 10.19439/j.sjos.2018.02.001 Abstract ( 268 )   PDF (2849KB) ( 301 )   Clear aligners and lingual appliances share common traits of physical invisibility, and therefore, clinical popularity. The marked differentiations between these two modalities, however, lie in treatment mechanisms and indications. This article summarized the accomplishments made and the challenges aroused in these two orthodontic mechanisms, advocating optimal selection of indications and proper use of these two appliances. Cautions are raised against excessive use of clear aligners by ignoring indication inspections. References | Related Articles | Metrics

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Influence of the arch-wire deformation on movement of the maxillary anterior teeth in the lingual retraction force system with micro-implant anchorage using 3-D finite element analysis ZHANG Ya, ZHANG Yi, JIANG Qin, WANG Hua-qiao, QIU Liang-xing, WANG Chao 2018, 27 (2):  117-122.  doi: 10.19439/j.sjos.2018.02.002 Abstract ( 285 )   PDF (4418KB) ( 182 )   PURPOSE: To evaluate the biomechanical effect of arch wire deformation, height of micro-implant and lever-arm on movement of the maxillary anterior teeth in the lingual retraction force system. METHODS: Nonlinear 3-D finite element model of lingual orthodontic force system with micro-implant was constructed. When the arch-wire was set to be flexible body and rigid body, lingual retraction force system using sliding mechanism, the height of micro-implant and lever-arm was 0, 3, 5, 7 mm to alveolar ridge crest of the middle point of maxillary second premolars and maxillary first molars. The initial movement and hydrostatic pressure of anterior teeth were calculated. RESULTS: In the lingual retraction force system with micro-implant using sliding mechanism, when the wire was set to be flexible body, retroclination primary displacements of maxillary anterior teeth were found because of wire deformation. The maxillary lateral incisor's primary displacement became larger with the height of micro-implant increased. When the wire was set to be rigid body, the teeth tended to be slightly tipping, and with the increase of height of micro-implant, the change of movement tendency was not obvious. High value of periodontal ligament hydrostatic pressure was observed in the lingual retraction force system of maxillary anterior teeth with micro-implant when the wire was flexible, exceeding the capillary pressure. When the wire was rigid, the value of periodontal ligament hydrostatic pressure was small within the upper limit value of capillary pressure. CONCLUSIONS: Deformation of wire has a great influence on initial teeth movement and periodontal hydrostatic pressure. In clinic, using more rigid wire and reducing the initial force may reduce the risk of orthodontic root absorption. References | Related Articles | Metrics

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Construction of cell sheets of stem cells from apical papilla and characterization of their biological properties MA Xue-juan, LIU Xue-mei, BI Jing, LIU Yao, CHEN Xu 2018, 27 (2):  123-128.  doi: 10.19439/j.sjos.2018.02.003 Abstract ( 346 )   PDF (5017KB) ( 271 )   PURPOSE: Cell sheets of stem cells from apical papilla (SCAP) were constructed. Their histological and biological properties were studied to provide experimental basis for its application in dental pulp regeneration in immature permanent teeth. METHODS: SCAP were isolated and cultured from immature permanent third molars. Flow cytometry was used to evaluate surface marker expression of SCAP. Alizarin red S staining was used to test osteo/odontogenic differentiation capacity of SCAP. SCAP (at P3) were cultured in cell sheets medium for 14 days. Hematoxylin-eosin(H-E) staining was used for histological observation; flow cytometry analysis was used to test cell cycle of SCAP cell sheets; Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), and collagen I (Col-I). Western blot was used to detect the protein expression levels of Runx2 and ALP. SPSS 17.00 software package was used for statistical analysis. RESULTS: H-E staining showed that SCAP cell sheets contained multiple layers of cells (5 to 6 layers) with high cell density, retained tight junctions and secreted rich extracellular matrix. The cell cycle of SCAP cell sheets showed that G2+S phase was lower, while G1 phase was higher than SCAP, which indicated the proliferation rate of SCAP cell sheets was down-regulated (P<0.05). Moreover, compared with SCAP, osteo/odontogenic differentiation capacity of SCAP cell sheets was significantly increased (P<0.05). CONCLUSIONS: SCAP cell sheets secret rich extracellular matrix, and osteo/odontogenic differentiation capacity in SCAP cell sheets is higher than SCAP. SCAP cell sheets may possess more potentials in dental pulp regeneration. References | Related Articles | Metrics

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Effect of akebiasaponin D with different concentrations on orthodontic tooth movement in rats CUI Jin-jie, WANG Xu-xia, WANG Yuan, CHEN Pei-pei, MA Dan, ZHANG Jun 2018, 27 (2):  129-134.  doi: 10.19439/j.sjos.2018.02.004 Abstract ( 310 )   PDF (4371KB) ( 177 )   PURPOSE: This study investigated the effect of local injection of akebiasaponin D (ASD) with different concentrations on the rate of orthodontic tooth movement in rats. METHODS: Forty 6-week-old female Wistar rats were randomly divided into 4 groups with 10 rats in each group. Animal model for orthodontic tooth movement was established. The upper first molars of the rats were moved mesially by coil springs（force=40 g）. ASD solution at the concentration of 5 mg/kg was locally injected in ASD1 group, and ASD solution at the concentration of 10 mg/kg was locally injected in ASD2 group. The rats of group PGE2 were injected PGE2 solution at the concentration of 25 μg/kg. The same amount of normal saline was injected in the control group. The rats were sacrificed in batch on the 3rd, 7th, 14th, 21st and 28th days after orthodontic treatment. The distance between upper first molar and second molar was measured. H-E straining was performed to observe the changes of periodontal tissue and the amount of osteoclast. SPSS13.0 software package was used for statistical analysis. RESULTS: The distance between the first and second molar was successively increased compared with the control group. On day 3, there was significant difference between PGE2 group and the control group (P<0.05). On day 7, the distance between the first and second molar in PGE2 group and ASD2 group was significantly increased compared with the control group (P<0.05). The amount of tooth movement was significantly increased (P<0.05) in ASD1 group, ASD2 group and PGE2 group, compared with the control group on the 14th, 21st and 28th day. However, there was no significant difference (P>0.05) between ASD2 group and PGE2 group. Under microscope, the number of osteoclast was increased on the tension side, reaching a peak on day 21st, and decreased later. CONCLUSIONS: Local injection of ASD solution may accelerate orthodontic tooth movement. ASD solution at the dose of 10 mg/kg can accelerate orthodontic tooth movement efficiently similar to PGE2 solution, while ASD solution at the dose of 5 mg/kg is not as effectual as PGE2 solution. References | Related Articles | Metrics

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Establishment of a model of endoplasmic reticulum stress response in dental pulp cells induced by tunicamycin LI Li-fen, WEN Yang, JIANG Long, ZHU Ya-qin 2018, 27 (2):  135-138.  doi: 10.19439/j.sjos.2018.02.005 Abstract ( 304 )   PDF (2876KB) ( 152 )   PURPOSE: The aim of this study was to establish a model of endoplasmic reticulum (ER) stress in dental pulp cells(DPCs) induced by tunicamycin to better understand the molecular mechanism of DPCs related diseases mediated by ER stress. METHODS: DPCs were cultured using modified tissue explant technique in vitro and cultured in presence or absence of tunicamycin. DPCs' viability was measured by methylthiazol tetrazolium (MTT) assay. The mRNA level of ER stress markers was examined by RT-PCR. The data were analyzed with SPSS17.0 software package. RESULTS: The proliferative ability of DPCs decreased when exposed to tunicamycin in a dose-dependent manner. Treatment with tunicamycin resulted in up-regulation of ER stress genes, such as splicing x-box binding protein-1(sXBP1), activating transcription factor 4(ATF4), glucose-regulated protein 78(GRP78) and C/EBP homologous protein (CHOP). CONCLUSIONS: The results indicate that ER stress response is induced in DPCs by tunicamycin, and the ER stress model is successfully established. References | Related Articles | Metrics

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Effect of different root control attachments on the mesially movement of upper molar with plastic aligner ZENG Hong, WANG Chao, ZHOU Jian-Ping, WU Yan, DAI Hong-Wei 2018, 27 (2):  139-145.  doi: 10.19439/j.sjos.2018.02.006 Abstract ( 447 )   PDF (5317KB) ( 473 )   PURPOSE: Three-dimensional (3D) finite element analysis (FEA) was used to explore the mechanical effect of the upper molar with different root control attachment in plastic aligner-based orthodontic technology. METHODS: A three-dimensional(3D) finite element model was derived from a cone-beam CT(CBCT) scan data and then built in the software of Mimics, Geomagic, Solidworks and Ansys. A model with an upper left first molar and its periodontal apparatus, different types of light-cured composite attachments and thermoformed plastic aligners were constructed. Four models were constructed: model A without composite attachments, model B with vertical rectangular attachment, model C with one optimized semiterete attachment, model D with two optimized semiterete attachments. Four FE models were used to analyze the effects of initial force system and displacement pattern of the molar in plastic aligner-mediated simulating mesial movement with different attachments. The initial tooth displacement, tension-compression pattern at the PDL and Von Mises stress in mesial alveolar fossa of different FE models were compared. RESULTS: In model D with two optmisied semiterete attachments, the compression stress of mesial periodontal ligament and the stress of mesi alveolar fossa were most widely distributed. The rotation axis was closest to the apical foramen, the root control effect of the molar was the best. In model B with buccal vertical rectangular, the compression stress of mesial periodontal ligament closer to buccal side was obviously wider than that of the palate. The rotation center of the buccal side was obviously near the apical foramen than the palatal side. The effect of buccal root control was better than that of palatal side. In model C with one semiterete optimized attachment, the stress pattern of the periodontal ligament in the mesial surface and the displacement patterns were not significantly different from those of model A with no attachments, but the maximum displacement of model C was greater than that of model A. CONCLUSIONS: The addition of attachments increased the molar's movement efficiency. Two semiterete optimized attachments on the buccal side had the best root control effect during mesial movement of the molar, but all attachments achieved tipping movement of the molar. References | Related Articles | Metrics

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Accuracy of 3D reconstruction of pulp cavity in mandibular premolars based on cone-beam CT LI Jun, PAN Yi-huai, ZHAO Yu, LI Ling 2018, 27 (2):  146-149.  doi: 10.19439/j.sjos.2018.02.007 Abstract ( 358 )   PDF (2834KB) ( 196 )   PURPOSE: To analyze the accuracy of 3D reconstruction of pulp cavity in mandibular premolars based on cone-beam CT (CBCT). METHODS: Thirty-two extracted single-rooted mandibular premolars were randomly collected and scanned by micro-CT and CBCT. After image segmentation and 3D reconstruction, the surface model and volume model of the pulp cavity were rendered. By using Amira 5.0 software, each pairs of pulp cavity surface models were registered. The surface models reconstructed from micro-CT scanning were set as the references and the surface models reconstructed from CBCT were tested. The morphological differences between each pairs of surface models were calculated by Amira 5.0 software and represented by color-coded maps. The total 3D morphological difference value of each sample was recorded and the volume reconstruction differences between the two image acquisition techniques were analyzed. Statistical analysis was performed with SPSS 13.0 software package. RESULTS: The mean value of 3D morphological differences of 32 teeth was 0.27 mm. Distribution of the greatest morphological differences were mainly located in the apical portion of the pulp cavity and some small anatomical variation. The volume of the reconstructed models by micro-CT and CBCT were (34.89±4.36) mm3 and (27.32±4.83) mm3 respectively, and the difference was significant (P<0.05). CONCLUSIONS: When CBCT scanning is used to reconstruct pulp cavity of mandibular premolars, there is certain degree of information loss, which mainly distributes in the apical portion and small anatomical variation sites. Dentists should consider these characteristics during clinical application of CBCT. References | Related Articles | Metrics

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Evaluation of the changes of alveolar bone around the upper incisors after retraction with mini implant anchorage using cone-beam CT CHEN Xiang, ZHANG Xiang-feng, HUANG Qian-qian, ZHANG Yi, YU Feng, WANG Hua-qiao 2018, 27 (2):  150-155.  doi: 10.19439/j.sjos.2018.02.008 Abstract ( 366 )   PDF (4547KB) ( 265 )   PURPOSE: The aim of this clinical study was to evaluate the changes of alveolar bone morphology before and after upper incisors retraction with mini implant anchorage using cone-beam CT (CBCT). METHODS: Twenty-two young patients with dentoalveolar maxillary protrusion and extraction of 2 maxillary first premolars were evaluated with CBCT. CBCT scans were obtained before treatment and 3 months after retraction of the incisors. The movement patterns of the upper incisors were assessed with Mimics15.0. The labial and palatal alveolar plates at crest level, midroot level, and apical level for bone-thickness changes and labial and palatal vertical bone level during retraction of the maxillary anterior segments were assessed with Invivo5.0. Paired t tests were used to evaluate the changes. RESULTS: The edge of the maxillary incisor and the root apex appeared lingual movement horizontally, but the moving distance was larger than the root apex. The edge of the incisors was moved downward, and the root apex was moved upward obviously. The palatal thickness and total thickness of the alveolar bone showed significant decrease at the crest level and midroot level after retraction while the apical level showed significant increase(P<0.05). The palatal vertical bone level also showed great loss (P<0.05). CONCLUSIONS: After extensive retraction of the maxillary incisors, tilt movements are controlled with high traction hooks and microscrew implants. The decreases in palatal bone thickness are much more significant compared with the increases in labial bone thickness. Alveolar bone remodeling doesn't follow the movement of tooth, suggesting that the limitation of anterior teeth retraction should be taken into consideration. References | Related Articles | Metrics

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Study on root canal variation of maxillary premolar and its relationship to maxillary sinus by cone-beam CT WEI Meng-yao, WANG Xiao-li, LI Yan, GAO Ya 2018, 27 (2):  156-163.  doi: 10.19439/j.sjos.2018.02.009 Abstract ( 380 )   PDF (6136KB) ( 403 )   PURPOSE: To investigate the anatomic morphology of root and root canal system of maxillary premolars by using cone-beam computer tomography (CBCT), in order to provide imaging basis for clinical treatment. METHODS: CB CT images of 720 patients (aged from 18 to 67 years) were included. They were divided into 5 groups according to their ages：18-28,29-38,39-48,49-58 and>58 years old . The number of roots and root canals, root canal configuration, the distance between two orifices,root canal curvature,distance from apex to maxillary sinus,symmetry of the bilateral teeth and its relationship to age changes were analyzed statistically using SPSS21.0 software package. RESULTS: Double root canal of the first maxillary premolar accounted the most (89.72%), and type IV was the frequent type (57.78%) . The incidence of single root canal in the second maxillary premolar (53.06%) was slightly higher than double root canal (46.94%). Root canal type was mainly type I (53.06%). There was symmetrical distribution in the bilateral root and root canals of maxillary premolars. The detection rate of the single root canal was changed with age, and the distance between the two orifice was closely related to the root morphology. The detection rate of root curvature in maxillary first and second premolar was 32.53% and 21.50% in buccolingual direction. There was a certain proportion of S-type complex root canal.16.69% of the maxillary second premolar and maxillary sinus were closely related (d≤0.05 mm). CONCLUSIONS: The anatomical structure of root and root canal is complicated .The prevalence of the bilateral teeth presents symmetry and age-related changes.The curvature of root canal is complex, and the roots are closely related to maxillary sinus. References | Related Articles | Metrics

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Distribution of WNT10A gene rs10177996 polymorphism between Han and Uygur populations in Xinjiang area LIU Jia-lin, ZHAO Chun-ping, ZHANG Jia-yu, HAN Xiang-zhen, GE Shu-peng, DU Li-juan, HE Hui-yu 2018, 27 (2):  164-169.  doi: 10.19439/j.sjos.2018.02.010 Abstract ( 226 )   PDF (4142KB) ( 216 )   PURPOSE: To explore the characteristics of distribution of WNT10A gene rs10177996 polymorphism between Han and Uygur populations in Xinjiang area. METHODS: A cross-sectional survey on 154 Han individuals in Urumqi area and 134 Uygur individuals in Kashgar area was performed. Buccal epithelial cells were harvested using Cotton swab scraping, and DNA was extracted by special kit. After screening, the corresponding SNP segments of qualified samples were propagated by PCR. Dideoxy-mediated chain termination method was used for gene sequencing, and then, genotyping was conducted with corresponding software. Statistical analysis of genetic data was performed by SPSS 23.0 software package. RESULTS: Among Uygur nationality in Kashgar area, the frequencies of CC, CT, TT genetypes in rs10177996 were 8.21%, 30.60% and 61.19%, respectively. The allele frequency of C was 23.51% and T was 76.49%. Among Han nationality in Urumqi area, the frequencies on CC, CT, TT genetypes of rs10177996 were 9.74%, 43.51% and 46.75%, respectively. The allele frequency of C was 31.49% and T was 68.51%. When compared with Han nationality, the frequency of TT was significantly higher in Uygur nationality(P=0.046). When compared with European, the frequency of TT was significantly lower in Uygur nationality (P=0.05). When compared with European, the frequency of TT was significantly lower in Han nationality(P<0.01). Compared with European, the distribution on C allele frequency was significantly higher, the distribution on T allele frequency was significantly lower in Han nationality (P=0.033). However, there was no significant difference between Han nationality in Urumqi area and Uygur nationality in Kashgar area (P>0.05), and, between Uygur nationality in Kashgar area and European (P>0.05). Meanwhile, there was no significant difference in gender between Uygur nationality in Kashgar area and Han nationality in Urumqi area (P>0.05). CONCLUSIONS: The distributions of WNT10A gene rs10177996 SNP among Han nationality in Urumqi area, Uygur nationality in Kashgar area and the reported European population are obviously different. References | Related Articles | Metrics

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Clinical study on united crowns or bridges for restoration of posterior teeth with insufficient maxillary bone by means of maxillary tuberosity dental implants LUO Cui-fen, PENG Guo-guang, XIA Wei, FENG Yuan-hua, SHEN Lin, HUANG Xing-xiang 2018, 27 (2):  170-175.  doi: 10.19439/j.sjos.2018.02.011 Abstract ( 325 )   PDF (5112KB) ( 260 )   PERPOSE: To evaluate the clinical effect of united crowns or bridges for restoration of posterior teeth with insufficient maxillary bone by means of tilted dental implants. METHODS: Patients who underwent dental implant surgery in posterior teeth with insufficient maxillary bone were collected and divided into two groups (40 in each group). Patients in the experimental group were treated with titled dental implantation, while patients in the control group were treated with maxillary sinus lifting. Implant retention, marginal bone loss, incidence of adverse reactions, time needed for implantation and cost were recorded and analyzed with SPSS 19.0 software package. RESULTS: After follow up of 2 year, the experimental group had a cumulative survival rate of 100%, marginal bone resorption was (0.31±0.27)mm on average, no sinusitis and massive haemorrhage were noted, The control group had a cumulative survival rate of 96.43%, marginal bone resorption was (0.28±0.26) mm on average, sinusitis and massive haemorrhage occurred in 9.5%,4.8% of patients, the difference was not statistically significant（P>0.05）. In the experimental group, maxillary sinus mucosa perforation and postoperative pain occurred in 0%,7.5% of patients, duration of operation was （30.55±8.21）min, average cost of each implant was （6.9±0.5）thousand RMB; while in the control group, maxillary sinus mucosa perforation and postoperative pain occurred in 14.3%,28.6% of patients, duration of operation was （50.32±10.80）min, average cost of each implant was (0.98±0.06) thousand RMB, the difference was significant（P<0.05）. CONCLUSIONS: It is feasible to use united crowns or bridges for restoration of posterior teeth with insufficient maxillary bone by means of maxillary tuberosity dental implants. References | Related Articles | Metrics

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Investigation on the effects of different brackets on the three-dimensional direction of the arch in the non reduction treatment XU Liang, HUANG Xiao-hong, LIN Shan 2018, 27 (2):  176-180.  doi: 10.19439/j.sjos.2018.02.012 Abstract ( 202 )   PDF (3181KB) ( 188 )   PURPOSE: To compare the three-dimensional effect between traditional brackets and Damon self- ligating brackets on the arch during non-extraction treatment. METHODS: Forty-five patients with non-extraction treatment were included in this study. The patients were randomly divided into 3 groups. Patients in group A were treated with traditional brackets and Nickel titanium wire. Patients in group B were treated with Damon 3mx brackets and Cu-NiTi wire. Patients in group C were treated with traditional brackets and Cu-NiTi wire.Dentitions were aligned in each group according to the same order of arch wire and time. The widths of arch and cephalometric data, such as U1-SN, U1-PP, L1-MP, U6-PP (mm), L6-MP (mm) and other related datas, in T1 and T2 were measured and analyzed with SPSS 22.0 software package. RESULTS: Expansion and protrusion of the arch were observed, but there was no significant difference before and after treatment among 3 groups. CONCLUSIONS: There is no difference in the three-dimensional effect between Damon brackets and traditional brackets in non-extraction treatment of patients with mild crowding. References | Related Articles | Metrics

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Impact of comprehensive health education on oral care knowledge, attitude and practice in the elderly in long-term care institutions LI Xiao-li, LIU Ming-yu, CHENG Liang, ZHU Hong-fei, SHANG Shu-huan, CUI Dan 2018, 27 (2):  181-184.  doi: 10.19439/j.sjos.2018.02.013 Abstract ( 352 )   PDF (2716KB) ( 302 )   PURPOSE: To assess the impact of comprehensive health education on oral care knowledge, attitude and practice(KAP) of the elderly in the long-term care institutions and to provide references for oral health education among the elder people. METHODS: Elder people from 2 nursing centers in Wuhan were selected. The follow-up period was 6 months. Questionnaires were used to collect social-demographic characteristics and oral care KAP data at baseline, the third month and the sixth month, respectively. Comprehensive health education, toothpaste and toothbrushes were provided at baseline and the third month. The changes of oral care KAP were observed before and after interventions. SPSS21.0 software package was used for statistical analysis. RESULTS: A total of 144 subjects with a mean age of (72.43±9.41) years completed the study after 6 months. At baseline, the KAP scores were (28.57±19.19), (70.66±21.99) and (39.86±24.18), respectively. At the sixth month, the KAP scores were (91.06±9.55), (95.31±10.23) and (90.00±13.38), respectively and significant improvements were observed (F=913.714, P<0.001; F=114.042, P<0.001; F=349.887, P<0.001). Oral care knowledge and attitude, knowledge and practice, attitude and practice were positively correlated（β=0.173, P=0.038; β=0.269, P=0.001; β=0.197, P=0.018）. Social-demographic characteristics had no significant effect on KAP scores (P>0.05). CONCLUSIONS: Long-term care institutions should strengthen oral health education and improve oral care KAP, oral health status and oral health-related quality of life of the elder people. References | Related Articles | Metrics

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Influence of fixed orthodontic treatment on oral health-related quality of life in adolescent and adult: a comparative study WANG Ying-zi, WANG Xu-xia, ZHENG De-hua, WANG Qian-qian, YANG Pan-pan, ZHANG Jun 2018, 27 (2):  185-189.  doi: 10.19439/j.sjos.2018.02.014 Abstract ( 335 )   PDF (3651KB) ( 179 )   PROPOSE: To compare the changes in oral health-related quality of life(OHRQoL) among adolescent patients and adult patients during orthodontic treatment. METHODS: The clinical data were collected from 81 patients (aged 15 to 25 years old) who underwent comprehensive orthodontic treatment. The participants were divided into 2 groups: adolescent patients (n=43) and adult patients (n=38) by age. OHRQoL was assessed using the Oral Health Impact Profile (OHIP-14). All subjects were examined and interviewed at baseline and the end of 3 stages during orthodontics treatment. Friedman 2-way analysis of variance (ANOVA) and Wilcoxon signed rank tests were used to compare the relative changes of OHRQoL among different time points with SPSS 20.0 software package. RESULTS: The scores of OHIP-14 and all domains except communication disorder and social disability domain in adolescent and adult patients showed significant changes as well as a decrease trend. Only adults showed significant changes in communication disorder.Both groups had no significant difference. CONCLUSIONS: The impact of comprehensive orthodontic treatment on patients' OHRQoL is quite different. Orthodontists should pay attention to the differences and guide the patients accordingly. References | Related Articles | Metrics

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Cone-beam CT study of the characteristics of midpalatal suture at different age groups in a southern China population TANG Chen-yao, LUO Dan, LIU Si-ling, LI Wen-jie, LU Yan-qin 2018, 27 (2):  190-194.  doi: 10.19439/j.sjos.2018.02.015 Abstract ( 375 )   PDF (3504KB) ( 244 )   PURPOSE: The purpose of this cone-beam CT (CBCT) based study was to investigate the stages of palatal suture at different age groups as well as the bone density of the palatal suture in a south Chinese population. METHODS: The CBCT data of 113 patients with an age range from 4 to 36 years old were selected. All of them were reported to have normal growth. CBCT image data were selected in accordance with the inclusion criteria. By using Angelieri method, the palate was divided into 5 groups, and Chad Evans Larson bone density ratio was calculated for each patient. One-way ANOVA and LSD analysis were used to evaluate the average bone density ratio of the mid-palatal at each age stage as well as the mean value of palatal suture bone density at different stages with SPSS 22.0 software package. RESULTS: By comparing the density ratio of mid-palatal suture for each age group, no significant difference was noticed for the same stage regardless of the age (stage B, C and D) (P>0.05), significant difference was noticed between C and D(P<0.05),no significant difference was noticed for the suture density between group A and B as well as group C and D (P>0.05), significant difference was found for the suture density between A/C, A/D, A/E, B/C, B/D, B/E, C/D, and C/E groups(P<0.05). CONCLUSIONS: The mid-palatal suture density in children under 15 years may belong to stage A, B or C , which is significantly lower than group D and E; Patients of a palatal stage C stay within an age range from 11 to 18. No inner group difference is noticed inside group C. The average suture density of group C is significantly larger than group A and B, whereas smaller than group D and E. The results showed that CBCT can be a useful tool to guide rapid mid-palatal expansion in clinical practice. Patients who have a lower density mid-palatal suture can be expanded. References | Related Articles | Metrics

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Effect of 2 bleaching therapies on decoloring of stained dental fluorosis SUN Wen-jing, FENG Shuang-yu, ZHANG Hui, ZHANG Hong-zhe, DENG Jing 2018, 27 (2):  195-199.  doi: 10.19439/j.sjos.2018.02.016 Abstract ( 510 )   PDF (3612KB) ( 190 )   PURPOSE: To evaluate the clinical performance of at-home bleaching and its application in combination with cold-light bleaching for esthetic management of fluorosed teeth,providing guidance for clinicians to choose the right treatment regimen and communicate with patients successfully. METHODS: We divided 43 cases with stained dental fluorosis into 2 groups, with 22 cases in the at-home bleaching group and 21 in the combination therapy group. Stained spots were chosen and colorimetric assay was performed using CMYK colorimetric table before treatment. According to the color of the splash, the light and shade were divided into light grade, medium grade and heavy grade. The CMYK data of the selected point and complete decolorization ratio (stain decolorization rate) were recorded after cold-light bleaching, every 2 weeks and half a year later. Meanwhile, tooth sensitivity was recorded using visual analogue scale (VAS). Statistical analysis was performed using SPSS 17.0 software package. RESULTS: In the combination therapy group, the decolorization rates of light, medium and heavy stains were 73.44%, 8.70% and 0% immediately after cold-light bleaching respectively. At 2 weeks, in the at-home group, the postoperative decoloring rate was 64.17% in the light grade group and 4.44% in the medium grade group, respectively. In the combination therapy group, the postoperative decoloring rate was 100% in the light grade group and 63.04% in the medium grade group, respectively (P<0.01). The postoperative decoloring rate in the heavy grade group was 0%. At 4 weeks, in the at-home group, the postoperative decoloring rate was 100% in the light grade group, 73.33% in the medium grade group and 11.40% in the heavy grade group, respectively. In the combination therapy group, the postoperative decoloring rate was 100% in the medium grade group and 53.00% in the heavy grade group, respectively (P<0.01). At 6 weeks, in the at-home group, the postoperative decoloring rate was 100% in the medium grade group and 76.32% in the heavy grade group. In the combination therapy group, the postoperative decoloring rate was 94.00% in the heavy grade group (P<0.01). At 8 weeks, the postoperative decoloring rate was 95.61% in the heavy grade group of at-home group. Half a year after treatment, bleaching decoloration rate had no significant difference compared with that at the end of treatment (P>0.05). Tooth sensitivity was 45.45% in the at-home group and 80.95% in the combination therapy group (P<0.05). CONCLUSIONS: Fluorosed teeth show significantly better esthetic appearance after both the at-home bleaching and the combination therapy at 6-8 weeks, and can maintain stable for a long time. Cold-bleaching has faster decoloration speed, with the final decolorization rate of the stains unchanged. In addition, it increases the incidence of postoperative sensitivity of teeth. References | Related Articles | Metrics

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Effect of pulsed dye laser on inhibiting early scar after maxillofacial trauma DONG Yi-yun, TAO Lan, ZHOU Guo-yu, WANG Hai-ning, ZHU Ya-qin 2018, 27 (2):  200-203.  doi: 10.19439/j.sjos.2018.02.017 Abstract ( 317 )   PDF (3348KB) ( 187 )   PURPOSE: The study was designed to explore an effective method to control early scar after maxillofacial trauma and improve the satisfaction of clinical treatment. METHODS: Fifty skin lesions after maxillofacial trauma were divided into the experimental group and control group. Patients in the experimental group were treated with pulsed dye laser when taking out stitches, 15, 30 and 60 days later. Digital microscope photos were taken and lesion area was measured before and 3 months after laser irradiation. Adverse effects were recorded during and after each treatment as well. All patients were asked to rate their satisfaction at 3-month of follow-up. Statistical analysis was performed using SPSS 13.0 software package. RESULTS: The efficiency of the experimental group was 74% and 37 lesions were cured or significantly improved, while the efficiency rate was 22% in the control group. Area reduction of maxillofacial lesions before and after treatment between the two groups was significantly different (P<; 0.05). Patients in the experimental group were highly satisfied with the final outcomes. No severe adverse events were observed. CONCLUSIONS: Pulsed dye laser is safe and effective in inhibiting early scar following maxillofacial trauma . References | Related Articles | Metrics

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A novel magnetic orthopedic appliance in treatment of preadolescent mild skeletal Class Ⅲ patients ZHAO Ning, FENG Jing, HU Zheng, CHEN Rong-Jing 2018, 27 (2):  204-209.  doi: 10.19439/j.sjos.2018.02.018 Abstract ( 328 )   PDF (4058KB) ( 250 )   PURPOSE: This study was to develop an intraoral Class Ⅲ orthopedic appliance using attractive magnetic forces, and investigate the effect of magnetic orthopedic appliance (MOA-Ⅲ) on skeletal and dental structures in mild skeletal Class Ⅲ children. METHODS: Thirty patients (12 boys and 18 girls) with mild skeletal Class Ⅲ jaw discrepancies were treated with MOA-Ⅲ. The average age was 9 years 3 months at the beginning of the treatment. The mean treatment period was 6.6 months. A paired t test was carried out to evaluate 40 parameters measured on cephalometric radiographs. Another 18 untreated patients (7 boys and 11 girls) according to upper criteria served as control group. SPSS15.0 software package was used for data analysis. RESULTS: The MOA-Ⅲ produced significant positive changes in maxillomandibular relationship. The maxilla was displaced anteriorly with clockwise rotation. The mandible showed slight downward and backward rotation. No significant changes were displayed in the length of the mandibular body and mandibular ramous. Significant labial tipping of the upper incisors and lingual tipping of lower incisors were noted after treatment. The measurement of soft tissues indicated that the upper lip moved forward and the lower lip retruded backward. In control group, most of the cephalometric measurements were not significantly changed except for some mandibular skeletal measurements and soft tissue measurements. CONCLUSIONS: By comparing to the untreated control, this type of magnetic orthopedic appliance is effective in the early treatment of mild skeletal Class Ⅲ malocclusion children. References | Related Articles | Metrics

Systemic Review

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Meta-analysis of the condylar position with mandibular deviation LIU Shuai, ZHAO Zhen-jin, ZHAO Rui, ZHENG Xue-song, WANG Li-ping 2018, 27 (2):  210-215.  doi: 10.19439/j.sjos.2018.02.019 Abstract ( 304 )   PDF (5410KB) ( 283 )   PURPOSE: This study was aimed to analyze the differences of condylar position between the mandibular deviation and the individual normal occlusion. METHODS: Databases of PubMed,Embase ,CNKI ,Wanfang ,VIP and CBL were searched for the relevant articles about condylar position with mandibular deviation. The deadline was June 2017.Data quality evaluation and extraction were independently conducted by two authors. Then meta analysis was performed using Rev Man 5.3 software. RESULTS: Six articles on controlled study of the condylar position in patients with mandibular deviation and individuals with normal occlusion were included. 122 patients had mandibular deviation and 110 had normal occlusion. Meta analysis results showed that the condylar superior space[MD=-0.38,95%CI(-0.74,-0.01),P=0.04]and anterior space[MD=-0.72,95%CI(-0.99,-0.04),P<0.00001]of the deviation side in mandibular deviation group were significantly greater than that of the opposite side; The condylar posterior space[MD=-0.35,95%CI(0.25,0.45),P<0.00001]of the deviation side in mandibular deviation group was significantly smaller than that of the opposite side. The condylar posterior space of deviation side[MD=-0.58,95%CI(-0.88,-0.28),P=0.0002],opposite side[MD=-0.30,95%CI(-0.59,-0.00),P=0.05] and the anterior space of opposite side[MD=-0.85,95%CI(-1.58,-0.13),P=0.02] in the mandibular deviation group was significantly smaller than that in the individuals with normal occlusion; the differences were statistically significant. There was no significant difference in the condylar superior space between the deviation side[MD=-0.56,95%CI(-1.14,0.02),P=0.06] and the opposite side[MD=-0.58,95%CI(-1.27,0.10),P=0.10] and the anterior space[MD=-0.05,95%CI(-0.35,0.46),P=0.80]in deviation side in the mandibular deviation group ,comparing with individuals with normal occlusion. CONCLUSIONS: The condylar position of deviation side in patients with mandibular deviation is posterior and inferior, comparing with the opposite side. The condylar position of deviation side in patients with mandibular deviation is posterior, comparing with the individuals with normal occlusion. References | Related Articles | Metrics

Dental Nursing

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Retrospective study on postoperative complications and nursing measure for the oldest old patients receiving free flap reconstruction with head and neck cancers WANG Yue-ping, CHEN Yi-ming, JI Tong, HONG Shu-wen 2018, 27 (2):  216-220.  doi: 10.19439/j.sjos.2018.02.020 Abstract ( 452 )   PDF (3472KB) ( 191 )   PURPOSE: To analyze the postoperative complications and nursing measures for the oldest old patients with head and neck cancer, who received free flap reconstruction. METHODS: A retrospective study for oldest old patients treated in the department of Oromaxillofacial Head and Neck Oncology of our hospital from 2005 to 2015 was conducted. All patients with head and neck cancer received free flap reconstruction with age≥85 years were selected. Demographics, clinical, nursing information and prognosis were collected. SPSS 17.0 software package was used for data analysis. RESULTS: There were a total of 24 oldest old patients, among whom 15 were male and 9 were female. The median age was 86 years old, 20 patients had co-morbidity, 18 patients had ASA Ⅱ and 6 patients had ASA Ⅲ. The median operation time was 420 minutes, while the median intraoperative blood loss was 550 mL. 16 patients underwent tracheotomy, 9 patients suffered from postoperative surgical complications and 16 patients experienced postoperative medical complications. CONCLUSIONS: The oldest old patients with head and neck cancer have high possibility of postoperative complications. Preoperative assessment, accurate postoperative observation and nursing measures can reduce the negative impact of postoperative complications and improve prognosis effectively. References | Related Articles | Metrics

Dental Education

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Application of micro-lecture in standardized training of endodontic residents SHAO Li-na, QIU Li-hong, ZHAN Fu- liang, XUE Ming 2018, 27 (2):  221-224.  doi: 10.19439/j.sjos.2018.02.021 Abstract ( 191 )   PDF (2678KB) ( 170 )   PURPOSE: To apply micro-lecture in standardized training of endodontic residents, in order to improve training quality. METHODS: Twenty endodontic residents were randomly divided into 2 groups, 10 students in each group. One group were taught with micro-lecture while the other group with lecture-based learning (LBL). The teaching effect was measured with examination and questionnaire survey. The examination results were analyzed by Student's t test using SPSS 18.0 software package. RESULTS: Micro-lecture group was better than LBL group in practical test and total scores, there were significant differences between the two groups (P<0.05). Micro-lecture group was better than LBL group in didactic test, but there was no significant difference between the two groups (P>0.05). Questionnaire survey showed that micro-lecture was well accepted by residents for its novelty and flexibility, self-motivated learning ability was trained, communication between teachers and residents was enhanced, but the production level of micro-lecture video needs to be improved. CONCLUSIONS: Micro-lecture achieves satisfactory teaching effect, and can be applied in standardized training of endodontic residents. References | Related Articles | Metrics