Effect of posterior gingival smile on the perception of smile esthetics

Objectives: To evaluate and compare the influence of posterior gummy smile on the perception of smile esthetics by orthodontists, general-dentists and laypersons. Study Design: A frontal photograph of a smile with normal gum exposure was chosen and manipulated digitally using Adobe Photoshop C3 to generate three further images with posterior gum exposure of 4, 6 and 8mm. These four images were assessed by the three evaluator groups: orthodontists (n=40), general-dentists (n=40) and laypersons (n=40). Both orthodontists and dentists had at least ten years professional experience and laypersons were aged between 40-50 years. The proportion of men to women was 20:20 in each group. Evaluators awarded a score to the smile esthetics of each image: 1=acceptable, 2=moderately acceptable, 3=unacceptable. Afterwards, each evaluator placed the four images in order of esthetic preference. Results: No significant differences (p>0.05) were detected between the three evaluator groups for the photo without posterior gummy smile. The perception of smile esthetics for a the 4mm posterior gummy smile (median for orthodontists=2, general-dentists= 1, laypersons=1), the 6mm (median for orthodontists=2, general-dentists=1, laypersons=1) and the 8mm (median for orthodontists=3, general-dentists=2, laypersons=2) was significantly different between orthodontists and the other two evaluator groups (p<0.0017). The three evaluator groups coincided in placing the image with the 6mm gum exposure in first place in order of esthetic preference. Conclusions: Posterior gummy smile influences the perception of smile esthetics more negatively among orthodontists than the rest of the groups

Short-term effect of zoledronic acid upon fracture resistance of the mandibular condyle and femoral head in an animal model

Objective: The aim of this study was to compare the effects in terms of resistance to fracture of the mandibular condyle and femoral head following different doses of zoledronic acid in an animal model. Study design: A total of 80 adult male Sprague-Dawley rats were included in a prospective randomized study. The animals were randomly divided into four groups of 20 rats each. Group 1 (control) received sterile saline solution, while groups 2, 3 and 4 received a accumulated dose of 0.2 mg, 0.4 mg and 0.6 mg of zoledronic acid, respectively. The animals were sacrificed 28 days after the last dose, and the right hemimandible and the right femur were removed. The fracture strength was measured (in Newtons) with a universal test machine using a 1 kN load connected to a metal rod with one end angled at 30 degrees. The cross-head speed was 1 mm/min. Later, the specimens were observed under a scanning electron microscope with backscattered electron imaging (SEM- BSE). At last, chemical analysis and elemental mapping of the mineral bone composition were generated using a microanalytical system based on energy-dispersive and X-ray spectrometry (EDX). Results: A total of 160 fracture tests were performed. The fracture resistance increased in mandible and femur with a higher accumulated dose of zoledronic acid. Statistically significant differences were recorded versus the controls with all the studies groups. The chemical analysis in mandible showed a significantly increased of calcium and phosphorous to compare the control with all of the study groups; however, in femur no statistically significant differences between the four study groups were observed. Conclusions: The administration of bisphosphonates increases the fracture resistance in mandible and femur

A new use for self-etching resin adhesives: Cementing bone fragments

© 2010 Elsevier Ltd. This document is the Published version of a Published Work that appeared in final form in Journal of Dentistry. To access the final edited and published work see https://doi.org/10.1016/j.jdent.2010.06.002Objectives: To evaluate the bond capacities of four self-etching resin cements and the self-etching adhesives of the same manufacturer when used to cement bone fragments and compare them with a well-known N-butyl-2-cyanoacrylate bone adhesive. Methods: 125 cylindrical bone specimens from pig mandibular ramus bone were prepared using terphane burs and cemented to the corticals of 125 other specimens obtained from pig mandibular body bone using the following bond systems: Group A: Adper PLP/Relyx; group B: Optibond/Maxcem; group C: Hystoacryl; group D: AdheSE/Multilink; group E: G-Bond/G-Cem. Shear bond strength was measured 15 min after cement application using a universal testing machine. Results: Shear bond strength results: group A 2.54 ± 0.23 MPa; group B 4.83 ± 0.4 MPa; group C 2.90 ± 0.24 MPa; group D 2.10 ± 0.17 MPa; group E 4.22 ± 0.24 MPa. Values for shear bond strength were significantly greater for group B and E compared to groups A, C and D (p < 0.005, test Mann–Whitney). SEM images showed the presence of a hybrid layer similar to that formed by these bond systems when used on dentine. Conclusion: Within the limitations of an in vitro investigation, results show that self-etching resin cements together with self-etching adhesives may be used for cementing bone fragments

Influence of food-simulating liquids on bond strength of brackets bonded with a HEMA-free and HEMA-containing self-etching primer

© 2012 by The EH Angle Education and Research Foundation, Inc. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/. This document is the Published version of a Published Work that appeared in final form in Angle Orthodontist. To access the final edited and published work see https://doi.org/10.2319/032711-216.1Objective: To evaluate the effect of food-simulating liquids on bond strengths of brackets bonded with a HEMA-free and a HEMA-containing self-etching primer. Materials and Methods: Brackets were bonded to 280 bovine incisors that were divided into two groups: (1) Adper Prompt-L-Pop (Adper PLP)/Transbond-XT and (2) Transbond Plus self-etching primer (TSEP, HEMA-free)/Transbond-XT. Each group was evaluated under different storage conditions: 24 hours in water, thermocycling (T), T/12 weeks in water, T/12 weeks in 10% ethanol, T/12 weeks in 50% ethanol, T/12 weeks in 3% acetic acid, and T/12 weeks in olive oil. Shear bond strength was measured with a universal test machine. Results: TSEP and Adper PLP showed a significantly higher bond strength at 24 hours than at T/12 weeks in 50% ethanol (P  =  .000). For Adper PLP, the bond strength at 24 hours was significantly higher than T/12 weeks in water (P  =  .000). Significant differences were not detected between the two bonding procedures for the different storage conditions (P > .05). Conclusion: Owing to its hydrophilic nature, the bond strength produced by Adper PLP (a HEMA-containing self-etching primer) decreased significantly after T/12 weeks in water. Brackets bonded with both TSEP and Adper PLP showed significantly higher bond strengths at 24 hours than at T/12 weeks in 50% ethanol, probably due to the effect of ethanol at 50% on Transbond-XT

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

Effect of water contamination on the shear bond strength of five orthodontic adhesives

Objectives: To evaluate the shear bond strength and site of failure of brackets bonded to dry and wet enamel. Study design: 50 teeth were divided into ten groups of 5 teeth each (10 surfaces). In half the groups enamel was kept dry before bonding, and in the other half distilled water was applied to wet the surface after etching. The following groups were established: 1)Acid/Transbond-XT (dry/wet) XT; 2) Transbond Plus Self Etching Primer (TSEP)/Transbond-XT paste (dry/wet); 3) Concise (dry), Transbond MIP/Concise (wet), 4) FujiOrtho-LC (dry/ wet); 5) SmartBond (dry/wet). Brackets were bonded to both buccal and lingual surfaces. Specimens were stored in distilled water (24 hours at 37ºC) and thermocycled. Brackets were debonded using a Universal testing machine (cross-head speed 1 mm/min). Failure sites were classified using a stereomicroscope. Results: No significant differences in bond strength were detected between the adhesives under wet and dry conditions except for SmartBond, whose bond strength was significantly lower under dry conditions. For all the adhesives most bond failures were of mixed site location except for Smartbond, which failed at the adhesive-bracket interface. Conclusions: Under wet conditions the bonding capacity of the adhesives tested was similar than under dry conditions, with the exception of SmartBond which improved under wet conditions

Guía de práctica clínica para la prevención y manejo de las lesiones de mancha blanca asociadas al tratamiento de Ortodoncia

La prevalencia de Lesiones de Mancha Blanca (LMBs) durante el tratamiento con ortodoncia fija, y una vez retirados los brackets y otros aditamentos, es alta, sin que existan pautas claras para la prevención y manejo de estas lesiones. Existe una metodología muy dispar de estos trabajos que dificulta las comparaciones, así como extraer resultados concluyentes. Se ha llevado cabo una revisión de la literatura con el objetivo de poder establecer una guía de actuación de prevención y tratamiento de LMBs en pacientes portadores de ortodoncia fija basada en la evidencia actual publicada. Los agentes que persiguen la remineralización de las LMBs serían la primera opción a nivel clínico, ya que consiguen, en un alto porcentaje de casos, detener su progresión o, incluso, que desaparezcan, siendo un procedimiento no invasivo. Estos agentes remineralizadores serían de indicación tanto durante el tratamiento ortodóncico para prevenir la aparición de LMBs como para manejarlas si aparecieran y una vez retirados los brackets. Palabras clave: Lesiones de Mancha Blanca, ortodoncia, brakets, caries dental

Elaboración de material didáctico utilizando TIC’s como herramienta para motivar a los estudiantes que repiten matrícula para Grados en Ciencias

Memoria ID-0223. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2016-2017

The ALHAMBRA survey: Estimation of the clustering signal encoded in the cosmic variance

[Aims]: The relative cosmic variance (σv) is a fundamental source of uncertainty in pencil-beam surveys and, as a particular case of count-in-cell statistics, can be used to estimate the bias between galaxies and their underlying dark-matter distribution. Our goal is to test the significance of the clustering information encoded in the σv measured in the ALHAMBRA survey. [Methods]: We measure the cosmic variance of several galaxy populations selected with B-band luminosity at 0.35 ≤ z< 1.05 as the intrinsic dispersion in the number density distribution derived from the 48 ALHAMBRA subfields. We compare the observational σv with the cosmic variance of the dark matter expected from the theory, σv,dm. This provides an estimation of the galaxy bias b. [Results]: The galaxy bias from the cosmic variance is in excellent agreement with the bias estimated by two-point correlation function analysis in ALHAMBRA. This holds for different redshift bins, for red and blue subsamples, and for several B-band luminosity selections. We find that b increases with the B-band luminosity and the redshift, as expected from previous work. Moreover, red galaxies have a larger bias than blue galaxies, with a relative bias of brel = 1.4 ± 0.2. [Conclusions]: Our results demonstrate that the cosmic variance measured in ALHAMBRA is due to the clustering of galaxies and can be used to characterise the σv affecting pencil-beam surveys. In addition, it can also be used to estimate the galaxy bias b from a method independent of correlation functions.This work has been mainly funded by the FITE (Fondos de Inversiones de Teruel) and the projects AYA2012-30789, AYA2006-14056, and CSD2007-00060. We also acknowledge support from the Spanish Ministry for Economy and Competitiveness and FEDER funds through grants AYA2010-15081, AYA2010-15169, AYA2010-22111-C03-01, AYA2010-22111-C03-02, AYA2011-29517-C03-01, AYA2012-39620, AYA2013-40611-P, AYA2013-42227-P, AYA2013-43188-P, AYA2013-48623-C2-1, AYA2013-48623-C2-2, ESP2013-48274, AYA2014-58861-C3-1, Aragon Government Research Group E103, Generalitat Valenciana projects Prometeo 2009/064 and PROMETEOII/2014/060, Junta de Andalucia grants TIC114, JA2828, P10-FQM-6444, and Generalitat de Catalunya project SGR-1398. A.J.C. and C.H.-M. are Ramon y Cajal fellows of the Spanish government. A. M. acknowledges the financial support of the Brazilian funding agency FAPESP (Post-doc fellowship - process number 2014/11806-9). M.P. acknowledges financial support from JAE-Doc program of the Spanish National Research Council (CSIC), co-funded by the European Social Fund.Peer Reviewe