In vivo study on metal release from fixed orthodontic appliances and DNA damage in oral mucosa cells

Interest in the amount of metal ion intake from dental alloys has grown. Fixed orthodontic appliances usually include brackets, bands, and archwires made of stainless steel, nickel-titanium, or nickel-cobalt alloys, and these can release metal ions. The purpose of this study was to investigate the biocompatibility in vivo of fixed orthodontic appliances, evaluating the presence of metal ions in oral mucosa cells, their cytotoxicity, and their possible genotoxic effects. Mucosa samples were collected by gentle brushing of the internal part of the right and left cheeks of 55 orthodontic patients and 30 control subjects who were not receiving orthodontic treatment. The cells were immediately prepared for cell viability and the comet assay. Nickel and cobalt cellular content was quantified by inductively coupled plasma mass spectrometry (ICP-MS). The results indicate that nickel and cobalt concentrations were 3.4-fold and 2.8-fold higher, respectively, in the patients than in the controls; cellular viability was significantly lower in the patients than in the controls, and there was a significant negative correlation with metal levels. The biologic effects, evaluated by alkaline comet assay, indicated that both metals induced DNA damage (more cells with comets and apoptotic cells). There were significant positive correlations between (1) cobalt levels and the number of comets and apoptotic cells, (2) nickel levels and number of comet cells, and (3) cobalt levels and comet tails. This study corroborates that nickel and cobalt released from fixed orthodontic appliances can induce DNA damage in oral mucosa cells.     

In vivo study of metal content of oral mucosa cells in patients with and without fixed orthodontic appliances

OBJECTIVE: To compare the concentration of nickel, chromium and cobalt in oral mucosa cells of patients with and without fixed orthodontic appliances. MATERIALS AND METHODS: A total of 60 patients were included in this study. The control group consisted of 30 patients without any type of fixed orthodontic appliances or metal restoration in the mouth (20 females and 10 males from 16 to 20 years with a mean age of 18 years). The test group consisted of 30 patients who had fixed orthodontic appliance in their upper and lower arches (20 females and 10 male from 16 to 20 years with a mean age of 18.2 years). The metal content determinations were carried out using atomic absorption spectrophotometry with a graphite furnace. RESULTS: According to spectrophotometric analysis, no significant differences in chromium (p = 0.09) and cobalt (p = 0.10) content of oral mucosa cells were found between the test and control samples. The nickel content in mucosa samples was significantly higher (p = 0.003) in orthodontic patients compared with the controls. The mean levels of nickel in control and orthodontic patient group were 12.26 and 21.74 ng / ml, respectively. CONCLUSION: Our findings indicate that there was no difference in the concentration of chromium and cobalt in oral mucosa cells of patients with or without fixed appliances. However, a significantly higher concentration of nickel can be found in oral mucosa cells of patients wearing fixed orthodontic appliances. Continued follow-up is needed to determine the long-term significance of nickel release.     

Microbial contamination of removable prosthodontic appliances from laboratories and impact of clinical storage

Decontamination of dental instruments has recently been the subject of considerable debate. However, little information is available on the potential bacterial colonisation of dental appliances returning from dental laboratories and their need for decontamination. This study investigated the extent and nature of microbial contamination of removable prosthodontic appliances produced at different dental laboratories and stored in two clinical teaching units (CTU 1 and CTU 2) of a dental hospital and school. Forty consecutive dental prosthodontic appliances that were being stored under varying conditions in the two clinical teaching units were selected for study; the appliances having been produced 'in-house' (hospital laboratory) or 'out-of-house' (external commercial laboratory). Two appliances, that were known to have undergone decontamination before storage, were used as controls. Swabs were taken according to a standard protocol and transferred to the microbiological laboratory with bacterial growth expressed as colony forming units (cfu) per cm(2). Microbial sampling yielded growth from 23 (58%) of the 40 appliances studied (CTU 1, n = 22; CTU 2, n = 18), with 38% of these having a high level of contamination (>42,000 cfu/cm(2)). The predominant bacteria isolated were Bacillus spp. (57%), pseudomonads (22%) and staphylococci (13%). Fungi of the genus Candida were detected in 38% of the samples. There was no significant difference in contamination of the appliances in relation to either their place of production or the CTU (p >0.05). However, the level of contamination was significantly higher (p = 0.035) for those appliances stored in plastic bag with fluid (n = 16) compared to those stored on models (n = 19). No growth was recovered from the two appliances that had undergone decontamination before storage. The research showed that appliances received from laboratories are often contaminated and therefore there is a need for routine disinfection of such items before use and a review of storage conditions required.     

Orthodontically induced external apical root resorption in patients treated with fixed appliances vs removable aligners

Objective:To determine whether orthodontic treatment with removable aligners vs fixed orthodontic appliances is associated with a different frequency of orthodontically induced external apical root resorption (OIEARR) when genetic, radiographic, and clinical factors are accounted for.Materials and Methods:Three hundred seventy-two orthodontic patients treated with removable aligners (Invisalign) or fixed appliances were genetically screened for interleukin 1B gene (IL1B) (rs1143634), interleukin 1 receptor antagonist gene (IL1RN) (rs419598), and osteopontin gene (SPP1) (rs9138/rs11730582). Twelve clinical variables, potentially associated with OIEARR, were also considered. Subjects were divided according to the presence of radiographically determined OIEARR (>2 mm). The association between OIEARR and appliance type, and radiographic, clinical and genetic factors, was assessed using backward stepwise conditional logistic regression. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported.Results:Reliability of the methods was adequate. Clinical case complexity (American Board of Orthodontics [ABO] Discrepancy Index) (OR: 1.032; 95% CI: 1.005–1.061; P = .021) and extent of incisor apical displacement in the sagittal plane (OR: 1.478; 95% CI: 1.285–1.699; P = .001) were associated with an increased OIEARR risk. After adjusting for associations between clinical/radiographic/genetic factors, there were no statistically significant differences with respect to OIEARR or type of orthodontic appliance used, whether removable aligners or fixed appliances (OR: 1.662; 95% CI: 0.945–2.924; P = .078). Only subjects homozygous for the T allele of IL1RN (rs419598) were more prone to OIEARR during orthodontic treatment (OR: 3.121; CI: 1.93–5.03; P < .001).Conclusions:A similar OIEARR predisposition was identified using either removable aligners (Invisalign) or fixed appliances.     

国产LF托槽与进口TOMY托槽脱落率及黏膜损伤的对比研究

目的对比研究LF托槽和进口TOMY托槽的托槽脱落率和黏膜损伤情况。方法正畸患者80例,LF组40例,粘接LF托槽800颗;TOMY组40例,粘接TOMY自锁托槽800颗,2组采用相同的方法和步骤进行粘接。每个月复诊时记录托槽脱落情况和创伤性口炎的发生情况,连续观察1年。结果 LF组的托槽脱落率为8.38%(67/800),TOMY组的托槽脱落率为8.00%(64/800),2组托槽脱落率差异没有统计学意义(χ2=51.8,P=0.10)。LF组创伤性口炎总发病率为97.5%(39/40),TOMY组总发病率为50.0%(20/40),LF组高于TOMY组,差异有统计学意义(χ2=63.7,P=0.01)。结论国产LF托槽和进口TOMY托槽的脱落率相近,但国产LF托槽引起创伤性口炎的概率更高。     

无托槽隐形矫治器与固定矫治器对牙周状况影响的meta分析

目的 通过meta分析评价无托槽隐形矫治器与固定矫治器相比对牙周状况的影响。方法 计算机检索PubMed、EMBASE、The Cochrane Library、CNKI、CBM、Wanfang Data数据库,查找从建库至2017年10月16日国内外公开发表的有关无托槽隐形矫治器与固定矫治器对牙周状况影响的文献。2名研究者独立按照纳入和排除标准筛选文献、提取资料。应用RevMan 5.3软件对提取的数据进行 meta 分析。结果 共纳入11篇文献,543例患者。Meta分析结果显示,除3个月的牙龈指数与6个月的探诊深度的牙周指数无显著差异外,配戴2种矫治器患者的其余牙周指数具有显著差异（P<0.05）,即无托槽隐形矫治器组的牙周指数显著低于固定矫治器组。结论 在正畸治疗矫治初期,无托槽隐形矫治器较固定矫治器更有利于牙周组织健康。     

Effect of removable orthodontic appliances on oral colonisation by mutans streptococci in children

Little is known about the effect of removable orthodontic appliances on oral colonisation by mutans streptococci (MS). In the present study, the frequency of isolation and serotype distribution of MS were evaluated in two groups of children, one undergoing therapy with removable appliances and the other not subjected to any kind of orthodontic treatment, respectively. Streptococci isolated from dental plaque samples from both groups of children were identified as mutans streptococci on the basis of their morphological and biochemical properties and were then serotyped in an enzyme immuno-assay using monoclonal antibodies. The number of subjects harbouring MS in their dental plaque was statistically higher in the group of orthodontic children without caries experience (CF) in comparison with CF children of the control group (10/12, 83.3% vs. 15/44, 34%). No clear difference was observed in the distribution of the different MS serotypes between the experimental and control group: S. mutans c,f serotype was the most frequently isolated in both groups of children followed by S. mutans serotype e and S. sobrinus serotype g. Such results suggest that the use of removable appliances may lead to the creation of new retentive areas and surfaces, which favour the local adherence and growth of MS. The data obtained stress the importance of a careful monitoring of patients treated orthodontically for risk of caries development.     

Objective assessment of compliance with intra- and extraoral removable appliances

Objective:To conduct an objective assessment of the level of compliance in young patients prescribed various types of removable appliances and to determine the influence of device type, treatment duration, and patient age, gender, psychological maturity, and awareness of monitoring on compliance.Materials and Methods:A total of 30 patients were fitted with either a class 2 (Frankel or bionator) or a class 3 (face mask) removable appliance, each bearing a compliance indicator chip, and they were instructed to wear them for 13 hours per day. Compliance was monitored by means of the sensor for an average of 8 months. Of the patients, 14 were informed that their appliance was fitted with a monitoring sensor, and 16 were not. The psychological maturity of all patients was assessed on the Nowicki-Strickland Locus of Control Scale, and the effect on compliance of this score as well as the patient- and treatment-related variables considered were determined via statistical analysisResults:The mean compliance recorded by the chips was 8.6 ± 2.9 hours, far lower than the 13 hours prescribed, and younger patients showed significantly greater compliance than adolescents (P < .01). However, no significant differences in compliance were found between intra- and extraoral appliances, and neither gender, psychological scores, treatment duration, nor awareness of being monitored had any significant effect.Conclusions:Compliance is generally very poor in young patients, regardless of their gender and psychological maturity. Although awareness of monitoring does not appear to boost compliance, such systems may be a valuable means of providing a dentist with objective information regarding their patients'' compliance.     

口腔X线检查对细胞损伤的探讨

目的 探讨常规口腔X线检查对口腔黏膜细胞的细胞毒作用.方法 收集24例受试者X线照射前及照射后7～10d的口腔颊黏膜脱落细胞,弗尔根染色及快绿染色后进行细胞学分析,计数1000个细胞中出现的微核数及其他类型细胞数,包括基底细胞、双核细胞、染色质固缩细胞、核碎裂细胞、核固缩细胞、核溶解细胞和核芽细胞,并进行统计学分析.结果 微核率比较:拍摄X线前为0.33‰,拍摄X线后为0.50‰,差异无统计学意义(P=0.465);其他类型细胞数比较,P值分别为0.603、0.547、0.078、0.141、0.470、0.626、0.655,差异均无统计学意义;＜18岁与≥18岁受试者照射X线后微核率与微核改变率差异均无统计学意义(P值为0.131与0.144.剂量与照射后核溶解细胞改变量有相关性(P =0.03),与微核及其他类型细胞改变量无相关性.结论 口腔常规X线检查的放射剂量与细胞凋亡率相关,＜18岁患者并未在X线照射中受到更多损伤.     

Assessing treatment effectiveness of removable and fixed orthodontic appliances with the occlusal index

Orthodontists from different backgrounds may have different opinions about removable and fixed orthodontic appliances, but there have been few objective comparisons of their relative treatment effectiveness. It is the purpose of the present study to analyze objectively the effectiveness of these two types of appliances. Eighty cases involving patients who had been treated with removable appliances and 67 cases of patients treated with fixed appliances were studied with respect to the Occlusal Index (OI). Scores indicating severity of malocclusion were obtained from pretreatment and posttreatment study casts. The effectiveness of the fixed appliance (represented by average reduction in OI score) was much greater than that of the removable appliance. The result of treatment with the fixed appliance was also found to be much better than that of the treatment with the removable appliance (indicated by the much lower posttreatment OI score in the fixed-appliance cases). The Occlusal Index was designed to measure features of basic malocclusion and is not a very sensitive index for assessing symptoms of a developing malocclusion. The fact that both the treatment effectiveness and the treatment results of the removable appliance were found to be inferior to those of the fixed appliance may indicate that the removable appliance has been used largely to correct "symptoms" rather than basic malocclusion.     

可摘式隐形矫治器与固定矫治器对牙周健康影响的比较研究

目的对比戴用可摘式隐形矫治器与固定矫治器后牙周指数的变化。方法选择18³2岁正畸患者80例,按矫治器类型分为2组:A组40例,佩戴可摘式隐形矫治器;B组40例,佩戴金属正畸托槽,分别检测40例患者治疗前和治疗后6周、6个月的各项牙周指数(GI、PLI、PD)。结果隐形矫治组牙周指数低于固定矫治器组,有显著性差异。结论与传统固定矫治器相比,可摘式隐形矫治器更有利于牙周组织的健康。     

上下颌活动／固定矫治器适配矫治严重Ⅲ类骨性反牙台

目的临床研究上下颌活动／固定矫治器的适配矫治生长发育期严重的Ⅲ类骨性反殆。方法共16名10～14岁以上颌后缩为主要表现的Ⅲ类骨性反殆患者，分为两组，一组佩戴上颌活动殆垫式的前牵矫治器的患者，下颌用固定矫治器；另一组上颌应用支架式快速扩弓加前牵的患者，下颌采用附有拉钩和殆垫的活动矫治器，每位患者均在治疗前和治疗后拍摄头颅侧位定位片和全口曲面断层片。结果16名患者经过治疗，不论从外形侧貌还是口内咬殆关系均基本达到正常。Ⅲ类咬合关系达到Ⅰ类咬合关系。SNA，ANB，1—1，IMPA和覆盖关系治疗前后差异显著，而SND，FMA，FMIA和覆胎治疗前后无显著差异性。结论上下颌活动／固定矫治器的适配，既能？肖除咬合干扰又能连续实施上颌骨矫形治疗，是一种临床有效的矫治骨性Ⅲ类反殆的好方法。     

In vivo behavior of complete human oral mucosa equivalents: characterization in athymic mice

Peña I, Junquera LM, Meana Á, García E, Aguilar C, Fresno MF. In vivo behavior of complete human oral mucosa equivalents: characterization in athymic mice. J Periodont Res 2011; 46: 214–220. © 2010 John Wiley & Sons A/S Background and Objective: The interest in tissue engineering as a way to achieve repair of damaged body tissues has led to the carrying out of many studies whose results point to the potential effectiveness of these methods. In a previous study, we reported the obtaining of complete autologous oral mucosa equivalents (CAOMEs), characterized by oral immature keratinocytes and stem cells on an autologous plasma and fibroblast scaffold. The purpose of this study is to show their behavior in vivo, by using them as free grafts in experimental animals, and to demonstrate their potential capacity to regenerate oral mucosa. Material and Methods: We engineered CAOMEs, as previously described. All CAOMEs thus obtained were used as free grafts in nu/nu mice. To assess their evolution in vivo, we studied their histological and immunohistochemical features by using AE1/AE3 pancytokeratin, the 5/6 cytokeratin pair, cytokeratin 13, laminin 5, collagen IV, vimentin, p‐63 and Ki‐67, at 7, 14 and 21 d. Results: The structure became progressively closer to that of oral mucosa samples. Cytokeratin 5/6 staining became increasingly intense in the basal and suprabasal layers, and cytokeratin 13 was exclusively positive in the superficial layers. The basal membrane was completed in 21 d. Vimentin showed a correct formation of the chorion. The increasingly positive staining of p‐63 and Ki‐67 indicated that the regeneration process was taking place. Conclusion: The present study shows the potential regenerative capacity of the CAOMEs by their ability to reach maturity similar to that seen in oral mucosa.     

Development of patient information leaflets for fixed,removable, and functional appliances for Arabic-speaking orthodontic patients

ObjectiveTo develop Orthodontic Patient Information Leaflets (PILs) in Arabic.Material & methodThis study included five phases starting with Arabic translation of existing British Orthodontic Society leaflets; initial face validation with three orthodontists; content validation with ten orthodontists; final face validation with ten orthodontists, five postgraduate students, and ten patients; and re-translation to English prior to comparing the new documents with the original PILs to verify that all the necessary information were included. The content validity index (CVI) assessed item level (I-CVI) and scale level (S-CVI).ResultsThe three Arabic PILs were face validated with inclusion of mini-screws, rapid maxillary expansion, and interproximal reduction. Content validity was perfect with no item I-CVI < 0.80. The S-CVI/Ave for PIL Fixed Appliances = 0.98, PIL Removable Appliances = 0.98 and PIL Functional Appliances = 0.97. In the final face validation, the three leaflets received 100% agreement from all observers for consistency of leaflet format and style, clarity, readability and use of adequate phrases. Finally, the leaflets were re-translated and the information was checked by native English speakers to ensure the completeness of information. There were no discrepancies and face validity was excellent.ConclusionValid PILs for Arabic-speaking patients undergoing orthodontic treatment with fixed, removable, and functional appliances have been developed.     

Postpubertal assessment of treatment timing for maxillary expansion and protraction therapy followed by fixed appliances.

In this cephalometric investigation, we evaluated the correction of Class III malocclusion in subjects who had attained postpubertal skeletal maturity and considered whether treatment timing influenced favorable craniofacial modifications. All subjects (n = 50) were treated with an initial phase of rapid maxillary expansion and protraction facemask therapy, followed by a second phase of preadjusted edgewise therapy. The treated sample was divided into an early treated group (early mixed or late deciduous dentition, 33 subjects) and a late treated group (late mixed dentition, 17 subjects). Mean treatment duration times were 7 years 2 months for the early treatment group and 4 years 5 months for the late treatment group. The treated patients were matched to untreated controls (early control group, 14 subjects; late control group, 10 subjects) on the basis of race, sex, mean age at first observation, mean age at second observation, mean observation intervals, and type of malocclusion. A modified version of Johnston's pitchfork analysis, with additional angular and linear measures for mandibular size and shape and for vertical skeletal relationships, was performed. Analysis of variance was used to evaluate the difference in means for each cephalometric variable in the treated groups compared with the corresponding control groups. The findings showed that orthopedic treatment of Class III malocclusion was more effective when it was initiated at an early developmental phase of the dentition (early mixed or late deciduous) rather than during later stages with respect to untreated Class III control groups. Patients treated with rapid maxillary expansion and facemask therapy in the late mixed dentition, however, still benefited from the treatment, but to a lesser degree. Early treatment produced significant favorable postpubertal modifications in both maxillary and mandibular structures, whereas late treatment induced only a significant restriction of mandibular growth. Significant changes in mandibular size were associated with significant changes in mandibular shape only in early treated subjects. The main contribution to overall occlusal correction was related to skeletal modifications rather than dental changes in both early and late treated groups.