Cytotoxicity evaluation of dental and orthodontic light-cured composite resins.

INTRODUCTION: The aim of this study was to determine the cytotoxicity of light-cured composite resins (Clearfil ES-2, Clearfil ES Flow, Filtek Supreme XTE, Grengloo, Blugloo, Transbond XT, and Transbond LR) then to assess leachable components in contact with human gingival fibroblasts (GFs) and to quantity detected bisphenol A (BPA). METHODS: Light-cured composite resin discs were immersed for 24 hours in gingival fibroblastic medium (n = 3 for each product) and in control medium (n = 2 for each product) contained in plate. Cytotoxicity of the products (n = 95) was determined by the measure of cell viability using MTT assay after reading the optical densities of the plates. The analysis of leachable components was done by gas phase chromatography and mass spectrometry (GC-MS) and detected BPA was quantified. The limit of quantification was 0.01 µg/mL. Statistical analyses were performed by using IBM SPSS Statistics 20 and Kruskal-Wallis and Mann-Whitney U-tests were applied. RESULTS: Cell viabilities were between 85 and 90%. Many chemical compounds including triethylene glycol dimethacrylate (TEGDMA) and BPA were identified. The average concentrations were 0.67 µg/mL ± 0.84 in the control medium and 0.73 µg/mL ± 1.05 in the fibroblastic medium. Filtek Supreme XTE presented the highest concentration of BPA with 2.16 µg/mL ± 0.65 and Clearfil ES Flow presented the lowest with 0.25 µg/mL ± 0.35. No BPA was detected with Transbond XT and Transbond LR. Clearfil ES Flow, Filtek Supreme XTE, Grengloo and Transbond LR presented residual TEGDMA. CONCLUSIONS: Light-cured composite resins are slightly cytotoxic opposite GFs and release many components including BPA and TEGDMA. Clinical precautions should be taken to decrease the release of these monomers.

Cephalometric norms of a Burkina Faso population.

INTRODUCTION: After a clinical examination, in order to implement an appropriate treatment planning, additional examinations such as lateral cephalograms, were performed. They were submitted to a cephalometric analysis such as the Tweed-Merrifield analysis. These cephalometric analyses based on a synthesis of aesthetic criteria established for a Caucasian European-American white people population could not serve as the reference for an African population. The aim of our study was to help establish the cephalometric norms of the Tweed-Merrifield's craniofacial and aesthetic analysis for a consulting population in the city of Ouagadougou. MATERIALS AND METHODS: This is a retrospective cross-sectional descriptive study conducted on a sample of lateral cephalograms selected among the files of patients consulting in the department of dental surgery at the Yalgado Ouédraogo university hospital centre of Ouagadougou. The patients were selected upon their balanced facial aesthetics. The same operator using acetate paper traced cephalogram on radiographs and collected the angular and linear values for the analysis. RESULTS: A total of 84 cephalograms, 42 male lateral cephalograms and the same number of females, were included. Their age ranged from 11 to 21 years old, with a mean age of 14.34 years. The mean SNA angle was 84.94°±2.59, the ANB angle was 4.88°. The vertical dimension was within the mean values, which was not the case for the mandibular incisor axis, very tipped buccally with an IMPA angle of 95.97°. The profile of the African subject was characterized by a closed Z angle. CONCLUSION: The profile of the African subject was rather prognathic, the maxilla and the mandible were prominent in relation to the cranial base. The maxillary-mandibular relationship is Ballard's class II. The typical alveolar biprotrusion must be considered as an ethnical data, which our treatment plans must consider.

Monomer release from orthodontic retentions: An in vitro study.

INTRODUCTION: The adhesives used to bond orthodontic retentions are low-loaded composite resins with a resinous matrix containing bisphenol A diglycidyl ether dimethacrylate synthesized from bisphenol A (BPA), fluidizers such as triethylene glycol dimethacrylate (TEGDMA) and hydrophilic polymers such as hydroxyethylmethacrylate. BPA disrupts the endocrine balance, and TEGDMA has high risks for human health: eg, allergies and cytotoxicity. The aim of this study was to evaluate in vitro the release of monomers from orthodontic bonded retentions. METHODS: A reproducible model of bonded retentions was carried out using calibrated molds. We analyzed the release of monomers by gas phase chromatography coupled with mass spectrometry. RESULTS: This model allowed us to qualitatively and quantitatively evaluate the in-vitro release of monomers from orthodontic adhesives. The quantitative and qualitative analyses showed no BPA release above the 0.02 ppm detection limit. A greater release of TEGDMA was observed with Transbond LR (31.7 µg/mL) than with Transbond XT (13.12 µg/mL) (both, 3M Unitek, Monrovia, Calif). Other toxic components (iodobenzene, iodobiphenyl, triphenyl stibine, and so on) were also identified. CONCLUSIONS: Toxic and carcinogenic molecules not mentioned in the material safety data sheets were identified.

Release of monomers from orthodontic adhesives.

INTRODUCTION: Most composite resins release both bisphenol A (BPA), which disrupts the endocrine balance, and triethylene glycol dimethacrylate (TEGDMA), which has high risks for human health: eg, allergies and cytotoxicity. The aim of this study was to characterize monomers released from orthodontic adhesives. METHODS: We studied samples of orthodontic adhesives by associating 2 techniques: gas phase chromatography and mass spectrometry. RESULTS: The in-vitro analysis detected significant quantities of BPA, TEGDMA, and other monomers in orthodontic adhesives used in daily practice: Transbond XT, Transbond Supreme LV (both, 3M Unitek, Monrovia, Calif), Blugloo (Ormco, Orange, Calif), and MonoLok 2 (Rocky Mountain Orthodontics, Denver, Colo). CONCLUSIONS: Clinicians should consider that orthodontic adhesives contain BPA, an endocrine disruptor; TEGDMA, an allergic and a cytotoxic compound; and carcinogenic genotoxic compounds. These molecules are not mentioned in the material safety data sheets. Manufacturers should declare all components of dental composites to identify these substances that may result in allergic or undesirable side effects for patients and dental staff.