Metallic ion content and damage to the DNA in oral mucosa cells of children with fixed orthodontic appliances

Although the metal devices used in orthodontic treatments are manufactured highly resistance to corrosion, they may still suffer some localized corrosion resulting from the oral cavity conditions. The corrosion causes the release of metals from the alloys used for their manufacture. In this report, we evaluated the in vivo metal ions release of three alloys (stainless steel, titanium and nickel-free) usually used in the orthodontics treatments and its genotoxicity. We applied to 15 patients, between 12 and 16 years, 4 tubes and 20 brackets. Samples from oral mucosa were taken before the treatment and 30 days later. The concentration of the titanium, chromium, manganese, cobalt, nickel, molybdenum and iron were detected using inductively coupled plasma mass spectrometry (ICP-MS). The genotoxicity was measured with a comet assay (Olive moment). The oral mucosa cells in contact with the stainless steel alloy displayed the greatest titanium and manganese concentrations and those in contact with the nickel-free alloy presented the greatest concentration of chromium and iron. Both alloys, stainless steel and nickel-free, induced a higher DNA damage in the oral mucosa cells than the titanium alloy, in which the Olive moment was similar to controls. Based on the results of our study, we can conclude that titanium brackets and tubes are the most biocompatible of the three alloys.     

Screening of biochemical parameters in the orthodontic treatment with the fixed appliances: A follow-up study

The aim of this study was to assess the changes in vital salivary parameters such as calcium, phosphorous, alkaline phosphatase, buffering capacity, pH, flow-rate and Oral Hygiene Index (OHI) in fixed orthodontic treatment patients during the retention period. In this study, saliva samples were collected from 35 patients before de-bonding (T₀) and after 4 to 5 weeks of de-bonding or on retention period (T₁). The biochemical parameters such as calcium, phosphorous and alkaline phosphatase levels were measured with saliva samples. Additionally, flow-rate, buffering capacity, pH and OHI levels was also measured. The current study results showed reduction in calcium, alkaline phosphatase, pH, flow-rate and OHI levels during T₁ (p < 0.05). However, phosphorous and buffering capacity levels were increased at T₁. The phosphorous levels showed non statistically significant difference when compared between T₀ and T₁ (p = 0.42). The remaining salivary parameters showed statistically significant difference when compared between T₀ and T₁ (p < 0.05). The present study concludes that there was a statistically significant decrease in the calcium, alkaline phosphatase, pH, flow rate and OHI values a month after de-bonding and increased in the buffering capacity values.     

Microbiological and clinical periodontal effects of fixed orthodontic appliances in pediatric patients

The aim of this study was to evaluate changes of microbiota in ten patients undergoing orthodontic treatment. For each patient clinical examination of gingival index (GI) and plaque index (PI) were performed at the first molars at: baseline (T1), 2 (T2), 4 (T3) and 12 weeks (T4). At the same time subgingival plaque and tongue samples were taken for the microbiological study. Clinical results showed that at T4, the mean PI score was significantly lower than T1 and the GI was markedly reduced. Microbiological results showed that at T1 and T4 facultative aerobic bacteria were prevalent, whereas anaerobic bacteria were more common at T2 and T3.     

DNA damage and repair in Helicobacter pylori-infected gastric mucosa cells

Helicobacter pylori is a common human pathogen and its infection is believed to contribute to gastric cancer. Impaired DNA repair may fuel up cancer transformation by the accumulation of mutation and increased susceptibility to exogenous carcinogens. To evaluate the role of infection of H. pylori in DNA damage and repair we determined: (1) the level of endogenous basal, oxidative and alkylative DNA damage, and (2) the efficacy of removal of DNA damage induced by hydrogen peroxide and the antibiotic amoxicillin in the H. pylori-infected and non-infected GMCs. DNA damage and the efficacy of DNA repair were evaluated by the alkaline single cell gel electrophoresis (comet assay). Specific damage to the DNA bases were assayed with the DNA repair enzymes formamidopyrimidine-DNA glycosylase (Fpg) recognizing oxidized DNA bases and 3-methyladenine-DNA glycosylase II (AlkA) recognizing alkylated bases. The level of basal and oxidative DNA in the infected GMCs was higher than non-infected cells. H. pylori-infected GMCs displayed enhanced susceptibility to hydrogen peroxide than control cells. There was no difference between the efficacy of DNA repair in the infected and non-infected cells after treatment with hydrogen peroxide and amoxicillin. Our results indicate that H. pylori infection may be correlated with oxidative DNA damage in GMCs. Therefore, these features can be considered as a risk marker for gastric cancer associated with H. pylori infection and the comet assay may be applied to evaluate this marker.     

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.     

Real time polymerase chain reaction analysis in the patients treated with fixed appliances after the orthodontic treatment: A follow-up study

This study aimed to compare the changes in the salivary cariogenic bacteria levels using qPCR and oral hygiene status after orthodontic treatment with fixed appliances during the retention phase concerning the patient and treatment variables. In this study, saliva samples were collected from 35 patients before debonding (T₀) and after five weeks of debonding on retention (T₁). The saliva samples were collected to extract the genomic DNA, and using specific probes and primers using real-time polymerase chain reaction was performed to analyze the changes in S. mutants, S. sobrinus, L. Casei after orthodontic treatment with fixed appliances. Additionally, OHI levels were also measured. The current study confirms the statistical association between T0 and T1 groups of S. mutants (p = 0.028) and S. sobrinus (p = 0.049). However, a lack of association was observed with L. Casei (p > 0.05). The number of bacteria was decreased from the T₀ group and increased in the T₁ group in Streptococcus mutants (S. mutants) and Streptococcus Sobrinus (S. sobrinus) while in Lactobacillus Casei (L. Casei) it was vice versa between T₀ and T₁ groups. The Oral Hygiene Levels (OHI) levels were also found to be statistically associated (p = 0.003). This study concludes that comparing the salivary cariogenic bacterial levels at T₀ (before debonding of fixed orthodontic appliances), with T1 (Five weeks after the debonding), and despite better oral hygiene, there was increase in salivary S mutants and S sobrinus levels. The current study suggested that orthodontic patients need careful hygienic procedures during the retention period. Future studies are recommended with additional follow-up and a large sample size.     

Genetic damage in exfoliated cells from oral mucosa of individuals exposed to X-rays during panoramic dental radiographies

The genotoxic effects of X-ray emitted during dental panoramic radiography were evaluated in exfoliated cells from oral epithelium through a differentiated protocol of the micronucleus test. Thirty-one healthy individuals agreed to participate in this study and were submitted to this procedure for diagnosis purpose after being requested by the dentist. All of them answered a questionnaire before the examination. Cells were obtained from both sides of the cheek by gentle scrapping with a cervical brush, immediately before the exposure and after 10 days. Cytological preparations were stained according to Feulgen-Rossenbeck reaction and analyzed under light and laser scanning confocal microscopies. Micronuclei, nuclear projections (buds and broken eggs) and degenerative nuclear alterations (condensed chromatin, karyolysis and karyorrhexis) were scored. The frequencies of micronuclei, karyolysis and pycnosis were similar before and after exposure (P > 0.90), whereas the condensation of the chromatin and the karyorrhexis increased significantly after exposure (P < 0.0001). In contrast, both bud and broken egg frequencies were significantly higher before the examination (P < 0.005), suggesting that these structures are associated to the normal epithelium differentiation. The results suggest that the X-ray exposure during panoramic dental radiography induces a cytotoxic effect by increasing apoptosis. We also believe that the score of other nuclear alterations in addition to the micronucleus improves the sensitivity of genotoxic effects detection.     

Comparative assessment of the cell-surface antigens and gene expression profiles of the gingival tissue biomarkers in subjects with fixed functional and removable functional orthodontic appliances

BackgroundThis study aimed to examine the cellular components of the gingiva during orthodontic treatment with fixed and removable appliances. The cellular and molecular cues of pathologies of the gingival tissue associated with the use of different orthodontic appliances could be studied.Materials and methodsTissue samples of gingiva were received from healthy patients undergoing gingivectomy for aesthetic purpose and from patients with fixed and removable functional orthodontic appliances undergoing gingivectomy for gingival overgrowth. The collected samples were stored in a sterile container with phosphate-buffered saline and to carry out further processes it was transported to the laboratory.ResultsCells positive for ECAD and NCAD were found to be increased in fixed appliances where as CD90 and CD105 positive cells showed no significant difference in all the three groups. CD24 and CD146 positive cells were increased significantly in removable and fixed than normal whereas CD133 positive cells were decreased in removable and fixed than normal. CD44 positive cells showed no noticeable change in all three groups. The gene expression levels of KRT5, SOX2, NANOG, and CXCL5 were found to be significantly increased in removable and fixed appliance groups. However, KRT8, CXCL10, and TIMP1 were increased only in fixed appliance group but CXCL10 showed decreased expression in removable appliance group. KRT6A, MYC, and MMP9 were decreased in fixed appliance group whereas MYC and MMP9 were increased in removable appliance group. KRT6A, KRT8, and TIMP1 showed no significant difference in removable appliance group.ConclusionThis study demonstrated essential roles of various genes, showing their contribution in regulating cell proliferation and migration in both the removable and fixed functional appliances.     

DNA damage and repair in children with Down's syndrome

Down's syndrome (DS) is associated with the presence of a third 21 chromosome and is generally considered as a non-cancer-prone genetic disease. However, leukaemias occur more frequently in children with the syndrome than in general population and there is an open question, whether the presence of an additional chromosome may contribute to genomic instability, which, in turn, may play a role in a higher susceptibility to cancer and leukaemias in particular. In order to assess genomic instability associated with the presence of a third 21 chromosome, we determined the level of endogenous DNA damage and susceptibility to a genotoxic stress-inducing factor, hydrogen peroxide and N-methyl-N'-nitro-N-nitrosoguanidyne (MNNG) as well as the ability to remove DNA damage in the peripheral blood lymphocytes of children with DS and healthy kids. The level of DNA damage and the kinetics of DNA repair were evaluated by alkaline comet assay. Oxidative DNA damage was assayed with DNA repair enzymes: endonuclease III-like NTH1 and formamidopyrimidine-DNA glycosylase. The cells taken from children with DS did not display an effective DNA repair after treatment with 10 mM hydrogen peroxide. No difference in the sensitivity to DNA-damaging agents and the efficacy of DNA repair due to age and gender in DS children was observed. These results suggest that children with DS may be characterized by the increased sensitivity to the DNA-damaging agents impaired cellular reaction to DNA damage, which, in turn, may increase the probability of cancers in these children. Therefore, a special care to avoid exposure to potential mutagenic factor my be considered in these children.     

DNA damage in human colonic mucosa cells induced by bleomycin and the protective action of vitamin E

Using the alkaline comet assay, we showed that bleomycin at 0.1-5 microg/ml induced DNA strand breaks and/or alkali-labile sites, measurable as the comet tail moment, in human colonic mucosa cells. This DNA damage was completely repaired during a 120-minute post-treatment incubation of the cells. Post-treatment of the bleomycin-damaged DNA with 3-methyladenine-DNA glycosylase II (AlkA), an enzyme recognizing alkylated bases, gave rise to a significant increase in the extent of DNA damage, indicating that the drug could induce alkylative bases in DNA. We did not observe any change in the comet tail moment in the presence of catalase. Vitamin E ((+)-alpha -tocopherol) decreased DNA damage induced by bleomycin. The results obtained suggest that hydrogen peroxide might not be involved in the formation of DNA lesions induced by bleomycin in the colonic mucosa cells.     

Relative DNA content in lymphocytes and buccal mucosa of patients with sex chromosomal anomalies

Cytophotometric estimation of DNA values from human buccal mucosa and lymphocyte culture nuclei shows a difference related to different X chromosomal abnormalities, namely, del X, XO, XXX and XXY. The values in the buccal mucosa in all cases except XXX were similar to the normal XX and XY. In lymphocytes nuclei, however, a steady increase in the DNA content at a significant level could be related to an increase in the number of X chromosomes. The similarity in the DNA values of normal XX and XY controls may be attributed to asynchrony in the replication patterns of X and Y chromosomes.     

DNA damage and DNA repair in cultured human cells exposed to chromate

DNA damage and DNA repair have been observed in cultured human skin fibroblasts exposed to potassium chromate but not to a chromic glycine complex. DNA repair synthesis (unscheduled incorporation of [3H]thymidine (TdR)) was measured in cells during or following exposure to chromate and was significant for chromate concentrations above 10(-6) M. Maximal DNA repair was observed at about 10(-4) M chromate. DNA repair capacity was found to be saturated at this concentration. Chromate was stable for at least 8 h in culture medium and produced approximately a linear increase in repair with duration of exposure. DNA damage as determined by alkaline sucrose gradient sedimentation was detected after treatment for 1.5 h with 5 . 10(-4) M chromate. Exposure to 10(-7) M chromate solution for 7 days inhibited colony formation while acute (1 h) treatment was toxic at 5 . 10(-6) M. The chromic glycine complex was toxic above 10(-3) M for a 1-week exposure but was not observably toxic after a 1-h treatment. These results indicate that chromate and not chromic compounds may be the carcinogenic form for man. The nature of the ultimate carcinogen is discussed. These findings illustrate the utility of the DNA repair technique to study the effects on human cells of inorganic carcinogens and mutagens.     

口腔卫生预防措施对固定正畸患者牙周菌群和牙周临床指数的影响

目的 采用牙周洁治和强化的口腔健康教育方法,通过检测牙周菌群和牙周临床指数的动态变化,探讨口腔卫生预防措施对固定正畸患者牙周菌群的影响。方法 选择正畸初诊患者20例,平均分为试验组（T组）和对照组（C组）。于正畸治疗开始前检查右上颌第一磨牙16和右下颌中切牙41牙周状况,并采集其近中颊轴嵴处龈缘菌斑做细菌分离培养。T组于治疗前进行全口洁治,每月复诊加力时均给予口腔卫生检查,强调口腔卫生的重要性;C组仅在初诊时进行口腔卫生指导,其余不作处理。2组患者分别于矫治器安装后1、3和6个月进行临床及细菌学检查。结果 随观察时间的延长,T组颊侧菌斑指数和牙龈指数在第1、3、6个月时较基线降低;C组颊侧菌斑指数第6个月时较基线降低,舌侧探诊深度则升高（P＜0.05）。细菌检出率和检出量的变化在T组可见韦荣球菌属降低而弯曲杆菌属和Gn产黑色素厌氧杆菌（BPAR）升高,C组消化链球菌属和BPAR升高（P＜0.05）;BPAR在第3个月、消化链球菌属在第6个月时T组检出率低于C组（P＜0.05）,而细菌检出量和牙周临床指数在2组间没有观测到处理因素的作用（P＞0.05）。结论 正畸前即存在牙龈炎的患者,建议进行预防性牙周洁治;牙周洁治必须和口腔卫生教育、正确的日常菌斑控制措施结合进行。     

Chromosome damage and cytotoxicity in oral mucosa cells after 2 months of exposure to anabolic steroids (decadurabolin and winstrol) in weight lifting

The aim of the present study was to evaluate DNA damage (micronucleus) and cellular death (pyknosis, karyolysis and karyorrhexis) in exfoliated buccal mucosa cells from anabolic steroid users after 2 months of exposure. Two experimental groups consisting of 15 adult males who practise weight lifting and are anabolic steroid users or 15 adult males who practise weight lifting, but are non-anabolic steroid users, were recruited. In addition, 20 sedentary males, who do not practise any physical activity regularly, were matched by age with experimental groups. No significant statistical differences (p > 0.05) were noticed in individuals who practise physical activity only. On the other hand, an increase of micronucleated cells (MNCs) in anabolic steroid (decadurabulin and Winstrol) users was observed. Regarding cytotoxic parameters, the same observation has occurred, that is, significant statistical differences (p < 0.05) were noticed in the group exposed to anabolic steroids when compared with other controls, as depicted by high frequencies of pyknosis, karyolysis and karyorrhexis. Taken together, our results suggest that genomic instability and cytotoxicity are induced by anabolic steroid administration in oral mucosa cells as assessed by the micronucleus test.