Do soft drinks affect metal ions release from orthodontic appliances?

ObjectiveThe effect of orange juice and Coca Cola^® on the release of metal ions from fixed orthodontic appliances.Materials and methodsA continuous flow system designed for in vitro testing of orthodontic appliances was used. Orange juice/Coca Cola^® was flowing through the system alternately with artificial saliva for 5.5 and 18.5 h, respectively. The collected samples underwent a multielemental ICP-OES analysis in order to determine the metal ions release pattern in time.ResultsThe total mass of ions released from the appliance into orange juice and Coca Cola^® (respectively) during the experiment was calculated (μg): Ni (15.33; 37.75), Cr (3.604; 1.052), Fe (48.42; ≥156.1), Cu (57.87, 32.91), Mn (9.164; 41.16), Mo (9.999; 30.12), and Cd (0.5967; 2.173).ConclusionsIt was found that orange juice did not intensify the release of metal ions from orthodontic appliances, whereas Coca Cola^® caused increased release of Ni ions.     

In vivo determination of aluminum,cobalt, chromium,copper, nickel,titanium and vanadium in oral mucosa cells from orthodontic patients with mini-implants by Inductively coupled plasma-mass spectrometry (ICP-MS)

Miniscrews are used as orthodontic anchorage devices in the dentistry clinical practice but the in vivo metallic release from these structures has been not previously investigated. The aim of this study was to determine the content of Al, Co, Cr, Cu, Ni, Ti and V in oral mucosa cells of control subjects, patients under orthodontic treatment and with both, orthodontic treatment and miniscrew, in order to know the contribution of these mini-implants to the total metallic content. ICP-MS measurements revealed the following ascending order: Cr < Ni < Ti < Cu < Al, and Co and V were practically undetected. Significant differences in comparison to the control group were found for Cu in the orthodontic group, and for Ni in both, orthodontic and orthodontic + miniscrew groups. Potential correlations among metallic elements and with some clinical factors were also explored. These findings suggest that miniscrews do not increase significantly the metal release.     

Screening of fluoride analysis as a biochemical parameter in the orthodontic treatment using fixed appliances

Saliva is a critical and useful biological fluid necessary for good health and for the appropriate execution of mouth activities. Orthodontic biomaterials have a complex relationship with many components, including the oral environment. Treatment with fixed orthodontic appliances may causes dental caries. As a result, it is necessary to comprehend how orthodontic therapy and various fluoride regimens affect the chances of developing dental cavities as well as individual risk factors. Usage of fluoride will tend to reduce the caries in the patients diagnosed with the fixed orthodontic treatment. The aim of this study was to screen the biochemical parameter of the fluoride levels in the patients undergone and completed the treatment of orthodontic fixed appliances. In this study, 35 patients have been visited on day 1 as well as day 35 and categorized as T₀ and T₁ groups. Saliva samples were collected and fluoride levels were measured between T₀ and T₁ groups. Using the fluoride kit with the spectrophotometer, fluoride levels were measured. The results confirmed similar fluoride levels between T₀ (26.11 ± 4.86) and T₁ (27.71 ± 4.40) groups. There was no significant association observed in this study (p = 0.56). Fluoride might have no role in the patients undergoing orthodontic treatment.     

正畸牙移动相关信号通路研究进展

<正>畸牙移动是在机械力的作用下,通过对牙周膜产生牵张或压缩的力来引起牙周组织在生理限度内的组织改建,从而达到牙齿移动、矫治畸形的目的。由于没有明显的年龄限制,正畸矫治在全球范围已变得越来越普遍。因此,相关的研究也日益增多。牙齿移动的生物学基础是正畸力作用于牙周组织激活一系列信号转导通路,进而引起牙周膜的修复改建。为指导临床、加速正畸矫治疗程提供新的思路,本文综述了近年来有关正畸牙移动相关信号通路的研究进展。发现最新的研究集中在MAPK信号通路,Wnt/β-catenin信号通路,PI3K/AKt/m TOR信号通路,BMP-2信号通路,Caspase-3介导的凋亡通路较多。但是正畸牙移动引起的牙周组织改建是一个多种生物力学信号转导通路相互调节相互作用的过程,对于上述信号通路之间的相互关系还有待于我们更进一步的探索。     

Finite element modeling of superelastic nickel–titanium orthodontic wires

Thanks to its good corrosion resistance and biocompatibility, superelastic Ni–Ti wire alloys have been successfully used in orthodontic treatment. Therefore, it is important to quantify and evaluate the level of orthodontic force applied to the bracket and teeth in order to achieve tooth movement. In this study, three dimensional finite element models with a Gibbs-potential-based-formulation and thermodynamic principles were used. The aim was to evaluate the influence of possible intraoral temperature differences on the forces exerted by NiTi orthodontic arch wires with different cross sectional shapes and sizes. The prediction made by this phenomenological model, for superelastic tensile and bending tests, shows good agreement with the experimental data. A bending test is simulated to study the force variation of an orthodontic NiTi arch wire when it loaded up to the deflection of 3 mm, for this task one half of the arch wire and the 3 adjacent brackets were modeled. The results showed that the stress required for the martensite transformation increases with the increase of cross-sectional dimensions and temperature. Associated with this increase in stress, the plateau of this transformation becomes steeper. In addition, the area of the mechanical hysteresis, measured as the difference between the forces of the upper and lower plateau, increases.     

Frequency of premolar teeth extractions for orthodontic treatment

It is of interest to evaluate the frequency of premolar extractions during orthodontic treatment in patients reporting to the Saveetha dental hospital in Chennai from 2019-2020. We used the records from 987 patients who underwent orthodontic treatment from June 2019 to March 2020 in a dental hospital for this analysis. Digital case records of patients who underwent therapeutic extractions of premolars were isolated. A sample dataset of 340 case records were selected for this study. Data shows that 34.4% of subjects underwent premolar extractions amongst a total of 987 subjects who underwent orthodontic treatment. 89.4% of patients were Angle''s Class I malocclusion patients, and the rest were Class II patients. However, no premolar extractions were done in Class III patients. Data also shows that 67.1% of subjects underwent all 4 first premolar extractions and 13.2% underwent only upper first premolar extractions. Thus, a significant association was found between Type of Malocclusion and the Type of premolar extractions with p < 0.05. Moreover, only 34.4% of patients underwent premolar extractions and the majority of them underwent all 4 first premolar extractions.     

侵袭性牙周炎伴错牙合畸形患者牙周-正畸联合治疗前后血清SAA、leptin的变化及与牙周指标和辅助性T细胞亚群的相关性分析

摘要 目的：探讨侵袭性牙周炎伴错牙合畸形患者牙周-正畸联合治疗前后血清淀粉样蛋白A（SAA）、瘦素（leptin）的变化及与牙周指标和辅助性T细胞（Th）亚群的相关性。方法：选择2020年6月-2022年8月解放军总医院京中医疗区黄寺门诊部口腔科收治的80例侵袭性牙周炎伴错牙合畸形患者（牙周炎组）和65例于口腔门诊检查的健康志愿者（对照组）。所有患者均接受牙周-正畸联合治疗,治疗前后分别检测血清SAA、leptin水平以及外周血中Th1、Th2、Th17细胞占比,并评估牙周指标变化。Pearson相关性分析血清SAA、leptin水平与牙周指标以及外周血中Th1、Th2、Th17细胞占比的相关性。结果：牙周炎组治疗前血清SAA、leptin水平,外周血Th1、Th17细胞占比,出血指数（SBI）、菌斑指数（PLI）、附着丧失（AL）、牙周探诊深度（PD）高于对照组（P＜0.05）,外周血Th2细胞占比低于对照组（P＜0.05）。牙周炎组治疗后血清SAA、leptin水平,外周血Th1、Th17细胞占比,PLI、SBI、AL、PD较治疗前降低（P＜0.05）,外周血Th2细胞占比较治疗前增高（P＜0.05）。牙周炎组血清SAA、leptin与PLI、SBI、AL、PD,外周血Th1、Th17细胞占比呈正相关,与外周血Th2细胞占比呈负相关（P＜0.05）。结论：侵袭性牙周炎伴错牙合畸形患者血清SAA、leptin水平增高,经牙周-正畸联合治疗后下降,高水平SAA、leptin与牙周组织破坏程度以及Th亚群紊乱有关,检测血清SAA、leptin水平可评估侵袭性牙周炎牙周组织破坏程度以及细胞免疫状态。     

超声骨刀开窗术联合正畸牵引治疗上颌唇侧埋伏阻生尖牙的疗效观察

目的:研究超声骨刀开窗术联合正畸牵引治疗上颌唇侧埋伏阻生尖牙的临床疗效。方法:选取2013年7月到2015年4月我院收治的上颌唇侧埋伏阻生尖牙患者110例,按照随机数字表法将患者分为研究组和对照组,每组55例,研究组给予超声骨刀开窗术联合正畸牵引治疗,对照组给予传统开窗联合正畸牵引治疗,比较两组临床疗效。结果:研究组总有效率92.7%,对照组总有效率90.9%,两组比较差异无统计学意义(P0.05);研究组一次粘结成功率85.5%显著高于对照组的52.7%,两组比较差异具有统计学意义(P0.05);研究组术后疼痛和肿胀程度均显著低于对照组,两组比较差异具有统计学意义(P0.05)。结论:超声骨刀开窗术联合正畸牵引治疗上颌唇侧埋伏阻生尖牙疗效良好,且能显著降低术后反应。     

Computational and clinical investigation on the role of mechanical vibration on orthodontic tooth movement

The aim of this study is to investigate the biomechanics for orthodontic tooth movement (OTM) subjected to concurrent single-tooth vibration (50 Hz) with conventional orthodontic force application, via a clinical study and computational simulation. Thirteen patients were recruited in the clinical study, which involved distal retraction of maxillary canines with 1.5 N (150 g) force for 12 weeks. In a split mouth study, vibration and non-vibration sides were randomly assigned to each subject. Vibration of 50 Hz, of approximately 0.2 N (20 g) of magnitude, was applied on the buccal surface of maxillary canine for the vibration group. A mode-based steady-state dynamic finite element analysis (FEA) was conducted based on an anatomically detailed model, complying with the clinical protocol. Both the amounts of space closure and canine distalization of the vibration group were significantly higher than those of the control group, as measured intra-orally or on models (p < 0.05). Therefore it is indicated that a 50 Hz and 20 g single-tooth vibration can accelerate maxillary canine retraction. The volume-average hydrostatic stress (VHS) in the periodontal ligament (PDL) was computationally calculated to be higher with vibration compared with the control group for maxillary teeth and for both linguo-buccal and mesial-distal directions. An increase in vibratory frequency further amplified the PDL response before reaching a local natural frequency. An amplification of PDL response was also shown to be induced by vibration based on computational simulation. The vibration-enhanced OTM can be described by mild, vigorous and diminishing zones among which the mild zone is considered to be clinically beneficial.     

正畸矫治对上颌外伤切牙牙髓活力的影响

目的:研究正畸矫治对上颌外伤切牙牙髓活力的影响。方法:选取我院正畸科2006～2011年期间的病例60例,并按上颌切牙有无外伤史分为正畸外伤组和正畸无外伤组两组;选取我院牙体牙髓科2008-2011年期间上颌切牙有外伤但未行RCT(Rootcanal treatment)的病例30例,设为外伤无正畸组组。对三组间上颌切牙所患牙髓坏死的机率进行比较。结果:正畸外伤组与正畸无外伤组有显著性差别(P<0.01),正畸外伤组与外伤无正畸组亦有显著性差别(P<0.05)。而正畸无外伤组与外伤无正畸组没有显著性差别(P>0.05)。结论:正畸治疗患者中,有严重牙周损伤史的上颌切牙患牙髓坏死的机率要明显高于无外伤史的上颌切牙。