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 Smart- Bond, 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

Bond strength of orthodontic brackets using different light and self-curing cements

The purpose of the study was to evaluate the shear bond strength of stainless steel orthodontic brackets directly bonded to extracted human premolar teeth. Fifty teeth were randomly divided into ¿ve groups: (1) System One (chemically cured composite resin), (2) Light Bond (light-cured composite resin), (3) Vivaglass Cem (self-curing glass ionomer cement), (4) Fuji Ortho LC (light-cured glass ionomer cement) used after 37% orthophosphoric acid¿etching of enamel (5) Fuji Ortho LC without orthophosphoric acid¿etching. The brackets were placed on the buccal and lingual surfaces of each tooth, and the specimens were stored in distilled water (24 hours) at 378C and thermocycled. Teeth were mounted on acrylic block frames, and brackets were debonded using an Instron machine. Shear bond strength values at fracture (Nw)were recorded. ANOVA and Student-Newman-Keuls multiple comparison tests were performed (P , .05). Bonding failure site was recorded by stereomicroscope and analyzed by Chi-square test, selected specimens of each group were observed by scanning electron microscope. System One attained the highest bond strength. Light Bond and Fuji Ortho LC, when using an acid-etching technique, obtained bond strengths that were within the range of estimated bond strength values for successful clinical bonding. Fuji Ortho LC and Vivaglass Cem left an almost clean enamel surface after debracketing.

El Misterio de la biblioteca Mil.lènium o cómo promover relaciones colaborativas desde la participación del alumnado = The Mystery of the Mil.lènium Library: How to Promote Collaborative Relationships Through Student Participation

La pedagogía crítica acentúa la falta de neutralidad de la escuela respecto a las relaciones de poder que existen en la sociedad. Su propuesta consiste en modificar las relaciones de poder en el aula en el sentido de transformar las relaciones coercitivas –las que reproducen las relaciones existentes– en relaciones colaborativas partiendo del reconocimiento y la participación de los alumnos en las actividades escolares. Desde esta perspectiva, uno de los objetivos de las actividades es que los niños produzcan «textos identitarios», entendidos como artefactos que los alumnos se pueden apropiar para promover su desarrollo cognitivo. El artículo muestra el trabajo educativo integrado desde Educación Infantil hasta 6.º de Primaria de una escuela de la provincia de Girona en la que el 97% de los alumnos es de origen extranjero y cuyo propósito es incrementar las habilidades lingüísticas orales y escritas en la lengua escolar, así como la utilización de otros lenguajes multimedia. La unidad didáctica consiste en la elaboración de un cuento a lo largo de un curso escolar por parte de todo el alumnado con la ayuda de los profesores, de dos autores y de tres ilustradores. Cada ciclo escolar decide los personajes y el escenario y explicita textualmente el transcurso de la acción. Los ilustradores producen las imágenes y los autores posibilitan la transición de aquello que ha elaborado un ciclo al producto del siguiente. La actividad basada en la participación y la utilización de procedimientos democráticos de decisión se inserta en la propuesta educativa y lingüística de la escuela, así como en sus concreciones curriculares. Los resultados muestran que los textos construidos por los niños se apoyan en sus «fondos de conocimiento» sociales y familiares y constituyen una fuente de progreso en la consecución de las competencias básicas y en la construcción de valores democráticos

Evaluation of the indication for surgical extraction of third molars according to the oral surgeon and the primary care dentist. Experience in the Master of Oral Surgery and Implantology at Barcelona University Dental School

Introduction: Third molar extraction is the most frequent procedure in oral surgery. The present study evaluates the indication of third molar extraction as established by the primary care dentist (PCD) and the oral surgeon, and compares the justification for extraction with the principal reason for patient consultation. Patients and method: A descriptive study was made of 319 patients subjected to surgical removal of a third molar in the context of the Master of Oral Surgery and Implantology (Barcelona University Dental School, Barcelona, Spain) between July 2004 and March 2005. The following parameters were evaluated: sex, age, molar, type of impaction, position according to the classifications of Pell and Gregory and of Winter, and the reasons justifying extraction. Results: The lower third molars were the most commonly extracted molars (73.7%). A total of 69.6% of the teeth were covered by soft tissues only. Fifty-six percent of the lower molars corresponded to Pell and Gregory Class IIB, while 42.1% were in the vertical position. The most common reason for patient reference to our Service of Oral Surgery on the part of the PCD was prophylactic removal (51.0% versus 46.1% in the case of the oral surgeon). Discussion and conclusions. Our results show prophylaxis to be the principal indication of third molar extraction, followed by orthodontic reasons. Regarding third molars with associated clinical symptoms or signs, infectious disease-including pericoronitis- was the pathology most often observed by the oral surgeon, followed by caries. This order of frequency was seen to invert in the case of third molars referred for extraction by the PCD. A vertical position predominated among the third molars with associated pathology

Periodontal health and esthetic results in impacted teeth exposed by apically positioned flap technique

Objectives: This study evaluates the periodontal health status and the esthetic results of teeth subjected to orthodontic traction, after their exposure by an apically positioned flap. Study design: Fifteen patients were included in the study, ages between 11 and 28 years old. The fenestrated teeth and their homologous contralateral normally erupted teeth, used as control, were evaluated. Results: Statistically significant differences were found in the position of the gingival margin (p = 0.005), with an average distance between cemento-enamel junction (CEJ) and gingival margin of 2.47 mm (SD 1.19) in control teeth and of 1 mm (SD 1.31) in the operated teeth, and in the depth of palatal probing (p = 0.031), with 2.1 mm (SD 0.9) for the experimental teeth and 1.7 mm (SD 0.8) for the control teeth. The gingival index, the bleeding during probing and the probing depth did not show statistically significant differences. The patient"s subjective esthetic evaluation was more favorable for the control teeth in most of the cases. Conclusions: The surgical approach for the impacted teeth by means of the apically positioned flap resulted to be a predictable technique allowing the maintenance of the periodontal health on a long-term basis.

Klammt's elastic open activator: Ricketts' cephalometrics results

The purpose of this study is to investigate the orthodontic and orthopaedic real effects of the Klammt's Elastic Open Activator (EOA) in 25 Class II Division 1 patients in growing period. We wanted to determine statistically the cephalometrics changes produced in the patients, comparing the lateral cranium teleradiographies we took for the diagnosis with the ones we took at the end of treatment. At the end of this study we confirm that by using the EOA we obtained the desired effects, especially reducing the molar relation 2.53 mm and the overjet 2.56 mm. The EOA corrected the inclination and protrusion of incisors, although we cannot avoid the use of fixed appliances to round off. The reduction of 2.48 mm of facial convexity stands out as the most important skeletal effect; the facial depth angle increases 0.8 degree, and the maxillary depth decreases 1.16 degrees. The length of the mandibular corpus also increases 6.7 mm, although this change is mainly due to the growth of the patient. The changes in the aesthetic profile do not stand out

Lower incisor dentoalveolar compensation and symphysis dimensions among Class I and III malocclusion patients with different facial vertical skeletal patterns

Objective: To compare lower incisor dentoalveolar compensation and mandible symphysis morphology among Class I and Class III malocclusion patients with different facial vertical skeletal patterns. Materials and Methods: Lower incisor extrusion and inclination, as well as buccal (LA) and lingual (LP) cortex depth, and mandibular symphysis height (LH) were measured in 107 lateral cephalometric x-rays of adult patients without prior orthodontic treatment. In addition, malocclusion type (Class I or III) and facial vertical skeletal pattern were considered. Through a principal component analysis (PCA) related variables were reduced. Simple regression equation and multivariate analyses of variance were also used. Results: Incisor mandibular plane angle (P < .001) and extrusion (P  =  .03) values showed significant differences between the sagittal malocclusion groups. Variations in the mandibular plane have a negative correlation with LA (Class I P  =  .03 and Class III P  =  .01) and a positive correlation with LH (Class I P  =  .01 and Class III P  =  .02) in both groups. Within the Class III group, there was a negative correlation between the mandibular plane and LP (P  =  .02). PCA showed that the tendency toward a long face causes the symphysis to elongate and narrow. In Class III, alveolar narrowing is also found in normal faces. Conclusions: Vertical facial pattern is a significant factor in mandibular symphysis alveolar morphology and lower incisor positioning, both for Class I and Class III patients. Short-faced Class III patients have a widened alveolar bone. However, for long-faced and normal-faced Class III, natural compensation elongates the symphysis and influences lower incisor position.