Canting of the occlusal plane: perceptions of dental professionals and laypersons

Objectives: To determine if canting of the occlusal plane influences esthetic evaluation of the smile among orthodontists, dentists and laypersons. Study Design: A frontal photo of a smile with 0º occlusal plane canting in relation to the bipupillary plane was modified using Adobe Photoshop C3 (Adobe Systems Inc, San José, California) to generate two images with occlusal plane inclinations of 2º and 4º. The three images were evaluated esthetically by orthodontists (n=40) general dentists (n=40) and laypersons (n=40). Each image was awarded a score as follows: 1=esthetically acceptable; 2=moderately acceptable; 3=esthetically unacceptable. Evaluators also placed the three images in order in preference. Data were analyzed using the Kruskal-Wallis (p<0.05) and the Mann-Whitney tests, applying the Bonferroni Correction (p<0.016). Results: No significant differences (p> 0.05) were found between the three groups for 0º and 2º cants (median for orthodontists=1; general dentists=1; laypersons=1). Orthodontists (median score=3) made evaluations of the image with 4º occlusal plane that were significantly different from general dentists (median=2) and laypersons (median=2). All three groups put the 0º image in first place in order of esthetic acceptability, the 2º image in second place and the 4º image in third place. Orthodontists placed the 0º image in first place with significantly greater frequency (p<0.016) than laypersons. Conclusions: Occlusal plane canting of 0º and 2º were evaluated as esthetically acceptable by the three groups. The 4º occlusal plane cant was evaluated more negatively by orthodontists than by general dentists and laypersons. All three groups placed the 0º image in first place of esthetic acceptability, 2º in second place and 4º in third. Orthodontists put the 0º image in first place with significantly greater frequency than laypersons

Toxicity of a dental adhesive compared with ionizing radiation and zoledronic acid

Background: To determine the toxicity of aqueous dilutions of a universal self-priming dental adhesive (DA) and comparing these with those elicited by exposure to ionizing radiation (IR), Zoledronic acid (Z) treatment and the synergic effects of the combined treatment with IR+Z. Material and Methods: The genotoxic effect of DA was determined by the increase in the frequency of micronuclei in cytokinesis-blocked in cultured human lymphocytes before and after exposure to 2Gy of X-rays. The cytotoxic effect was studied by using the MTT cell viability test in normal prostate cell lines (PNT2) after exposure to different X-ray doses (0Gy-20Gy). The cell lines divided into different groups and treated with different test substances: DA in presence of O 2 , DA in absence of O 2 , Z-treated and control. Results: An in vitro dose-dependent and time-dependent cytotoxic effect of DA, Z and IR on PNT2 cells ( p >0.001) was demonstrated. DA without-O 2 , following the recommendations of manufacturers, had a more pronounced effect of increasing cell death than DA with-O 2 ( p <0.001). In the genotoxicity assay, DA at 25% of its original concentration significantly increased chromosome damage ( p <0.001). The samples studied were found to be toxic, and the samples photo-polymerized in absence of O 2 showed a bigger cytotoxic effect comparable to the additive toxic effect showed by the combined treatment of IR+Z. Conclusions: Additional effort should be carried out to develop adhesives, which would reduce the release of hazardus substances; since toxic effects are similar to that reported by other agents whose clinical use is controlled by the health authorities

Disminución de los efectos genotóxicos, citotóxicos y radiosensibilizante de bisfosfonatos mediante antioxidantes : un modelo experimental

Objetivos: los objetivos esta tesis doctoral son determinar los efectos genotóxicos y citotóxicos de los bisfosfonatos en combinación con la radiación ionizante, con el fin de evaluar un posible efecto tóxico sinérgico de ambos tratamientos y determinar un posible efecto protector de algunos antioxidantes que podría permitir un aumento del efecto terapéutico y/o de las dosis administradas. Metodología: el efecto genotóxico se estudió con el test de micronúcleos en linfocitos humanos bloqueados citocinéticamente antes y después de una irradiación de 2 Gy; mientras que el efecto citotóxico se estudió con un ensayo de viabilidad celular (MTT) en las líneas celulares normales de próstata PNT2, tumorales de próstasta TRAMP-C1 y de melanoma metastásico B16F10 antes y después de la exposición a diferentes dosis de rayos X (0-20 Gy) en tratamientos combinados con bisfosfonatos (ácido zoledrónico, ibandronato y pamidronato) y con antioxidantes (apigenina, carnosol y ácido rosmarínico). Resultados y Conclusiones: los bisfosfonatos presentaron un efecto citotóxico según la dosis administrada, destacando la capacidad genotóxica y citotóxica de ácido zoledronico; y un efecto citotóxico sinérgico en el tratamiento combinado de radiación ionizante con ácido zoledronico. La administración de ciertos antioxidantes junto con los bisfosfonatos reduce la toxicidad de estos. La administración de antioxidantes disminuye el efecto lesivo inducido por la radiación ionizante, comportándose como una sustancia radioprotectora tanto del tumor como de las células normales no tumorales. Sin embargo, el carnosol y el ácido rosmarínico mostraron un efecto paradójico en las células del melanoma, ya que se comportan como radiosensibilizadores en estas células, por lo que podrían permitir una nueva estrategia que implicaría un efecto radiosensibilizador en estas células tumorales, pero al mismo tiempo con un efecto radioprotector en el tejido normal adyacente incluido en el mismo campo de irradiación. ABSTRACT Objectives: the aims this Doctoral Thesis are determine the genotoxic and cytotoxic effects of bisphosphonates both separately and in combination with ionizing radiation, in order to assess the possible existence of a synergically toxic effect resultant from both therapies and determine the potentially protective effect of antioxidants against the toxicity induced by the bisphosphonates which might enable an increase in their therapeutic effect and/or the dose administered. Methods: the genotoxic effect was studied by means of the micronucleus test in cytokinesisblocked cells of human lymphocytes irradiated before and after a 2 Gy irradiation, while the cytotoxic effect was studied by a cell viability test (MTT) in the PNT2, TRAMP-C1 and B16F10 cell line before and after exposure to different X-ray doses (0–20 Gy) in the combined treatments with bisphosphonates (zoledronic acid, ibandronate and pamidronate) and antioxidants (apigenin, carnosol and rosmarinic acid). Results & Conclusions: the bisphosphonates tested present a dose-dependent cytotoxic effect, highlighting the genotoxic and cytotoxic capacity of zoledronic acid and a synergic cytotoxic effect exists in the combined treatment of ionizing radiation plus zoledronic acid, while the administration of certain antioxidants together with bisphosphonates reduces toxicity. The administration of certain antioxidants diminishes the toxic effects induced by the ionizing radiation, behaving in a radioprotective manner in both tumour and normal, non-tumour cells. However, carnosol and rosmarinic acid display a paradoxical effect in melanoma cells since they behave in a radiosensitizing manner in melanoma cells only and thus might allow for a new strategy involving a radiosensitizing effect in the aforementioned cells, yet at the same time a protective effect in normal adjacent tissue