Enrique Solano

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.

Biomonitorization of chromium, copper, iron, manganese and nickel in scalp hair from orthodontic patients by atomic absorption spectrometry.

The study was aimed to assess Cu, Cr, Fe, Mn and Ni levels in human scalp hair from a broad population group treated with orthodontic appliances (n=70) to determine, whether the concentration of a given metal was significantly influenced by the orthodontic treatment in comparison to control group (n=56). Levels of metal compounds were determined by atomic absorption spectrometry. The mean, ranges, median and 5th and 95th percentiles of metals analyzed in hair that were hypothesized to be systemically absorbed from stainless steel, are provided. The influence of individual factors on metal concentrations was considered (gender, age), and inter-element interactions were studied by evaluation of correlation coefficients between elements, as well as by multiple regression analysis. Differences in the content of metals in hair were only significantly increased for Mn when compared to the control group, but their levels were of the same magnitude to other control populations, and consequently, no risks linked to the treatment have been found. The orthodontic treatment increased significantly Mn levels in young patients (<20 years old) when compared with control group. Scalp hair analysis is a good method to investigate the release of the elements from fixed orthodontic appliances.

Validation of a method to quantify titanium, vanadium and zirconium in oral mucosa cells by inductively coupled plasma-mass spectrometry (ICP-MS).

The release of metal ions from fixed orthodontic appliances is a source of major concern. Various studies have evaluated the discharge of metals from these appliances in biological fluids, such as saliva or blood, overlooking the cells with prolonged contact with fixed appliances. The aim of this work is to develop and optimize an analytical procedure to determine Ti, V and Zr in oral mucosa cells in patients with and without orthodontic appliances by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analytical procedure is based on an extraction and digestion of the samples and quantification of the elements. A suitable and practical procedure for assessing the trueness and precision of the proposed method has been applied by using validation standards. The method has been suitably validated: the regression equation was calculated from standards prepared in the same matrix without oral mucosa cells and the linear range was 0.5-50.0 ng/mL for Zr and 5.0-50.0 ng/mL for Ti and V. Limits of detection were 0.9, 2.8 and 0.4 ng/mL and limits of quantification 1.8, 3.4 and 0.7 ng/mL for Ti, V and Zr, respectively. The recovery percentages (%) obtained oscillated between 101 and 108 for Ti, 98 and 111 for V, and 92 and 104 for Zr. Intermediate precision (RSD%) data obtained were also adequate. The present method showed to be robust for the three factors considered: heating time, volume of the deionized water, and volume of PlasmaPure 65% HNO₃ used to dilute the samples, which permits its validation and application to oral mucosa cells from orthodontic patients.

In vitro and in vivo evidence of the cytotoxic and genotoxic effects of metal ions released by orthodontic appliances: A review.

Intraoral fixed orthodontic appliances are frequently used in the clinical practice of dentistry. They are made from alloys containing different metals at various percentages. The use of these appliances leads to the long-term exposure of patients to these materials, and the potential toxic effects of this exposure raises concerns about patient safety. Thus, the biocompatibility (corrosion behaviour and toxicity) of these materials has to be evaluated prior to clinical use. In the present report, the most recent studies in the scientific literature examining metal ion release from orthodontic appliances and the toxic effects of these ions have been reviewed with a special focus on cytotoxicity and genotoxicity. Previous studies suggest that a case-by-case safety evaluation is required to take into account the increasing variability of materials, their composition and the manufacturing processes. Moreover, in vivo toxicity studies in regard to metal release, cytotoxicity and genotoxicity are still scarce. Therefore, in vitro and in vivo monitoring studies are needed to establish cause-effect relationships between metal ion release and biomarkers of cytotoxicity and genotoxicity. Further investigations could be performed to elucidate the toxic mechanisms involved in the observed effects with a special emphasis on oxidative damage.

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.

Genotoxic and cytotoxic effects and gene expression changes induced by fixed orthodontic appliances in oral mucosa cells of patients: a systematic review

Abstract Context: The accumulation of chronic or severe acute DNA and cellular damage in oral mucosa cells is one of the main factors that help initiate a wide range of malignant lesions in the oral cavity. There has been considerable controversy in the literature about the effect of such sustained genotoxic and cytotoxic damage to oral mucosa cells. Objective: The aim of this systematic review, reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, is to investigate the effects of such interventions. Methods: Electronic and manual searches were performed (15 May 2015) for Randomized Clinical Trials/quasi-Randomized Clinical Trials that analyzed the genotoxic/cytotoxic effects of these types of oral appliances in humans. A primary outcome (cell/DNA damage) and a number of secondary outcomes were examined. Two reviewers carried out the study selection and performed a “risk of bias” assessment [Cochrane Collaborations tool]. Wherever possible the meta-analysis was conducted on homogenous groups. Results: From the electronic search (2797), 6 studies met the eligibility criteria. Most studies (5/6) observed significant differences in most comparisons at the short-term (1-3 months) and long-term (24–48 months) evaluations, with respect to critically acute genotoxic/cytotoxic effects. Some of the studies (2/3) concluded that the post-removable effects at DNA/cellular levels were not significant (p > 0.05) with respect to the controls. Conclusions: Acute DNA/cellular damage in oral mucosa cells is induced by orthodontic appliances. Nevertheless, even though these effects were no longer detected after removing the appliances, more rigorous RCTs are needed to explore the extent to which acquired damage can be observed in the oral mucosa.

Preliminary study of genotoxicity evaluation of orthodontic miniscrews on mucosa oral cells by the alkaline comet assay

Abstract Miniscrew implants are widely used nowadays in orthodontic treatments due to their good results in clinical practice. However, data regarding the biocompatibility of commercially available orthodontic miniscrews and temporary devices are very scarce, and their role as genotoxicity inducers has been not previously evaluated with the alkaline comet assay. The aim of this study was to investigate the DNA damage in buccal cells of patients subjected to orthodontic treatments. The alkaline comet assay has been applied in oral mucosa cells from patients treated with conventional orthodontic treatment in comparison to patients treated additionally with miniscrews, non-treated volunteers (control) and smoking volunteers (positive control). The application of orthodontic appliances and miniscrews induced significant and similar (2-fold) increases of %DNA in tail in comparison to control group. Females experienced a significant increase in %DNA in all the treatments in comparison to the control group, whereas males showed significant damage only with the combined orthodontic and miniscrew treatment. In conclusion, conventional orthodontic appliances induced genotoxicity, and the incorporation of miniscrews assayed did not imply any additional increase of DNA damage.