In Vitro Study of Preload Loss in Different Implant Abutment Connection Designs

The stability and integrity of the abutment-implant connection, by means of a screw, is fallible from the moment the prosthetic elements are joined and is dependent on the applied preload, wear of the components and function. One of the main causes of screw loosening is the loss of preload. The loosening of the screw-abutment can cause complications such as screw fracture, marginal gap, peri-implantitis, bacterial microleakage, loosening of the crown and discomfort of the patient. It is also reported that loosening of the screw/abutment may lead to a failure of osseointegration. It is necessary to evaluate and quantify, with in vitro studies, the torque loss before and after loading in the different connections. Aim: evaluate the influence of implant- abutment connection design in torque maintenance after single tightening, multiple tightening and multiple tightening followed by mechanical cycling. Materials and Methods: 180 Klockner implants divided in 4 groups: 15 SK2 external connection, 25 Ncm tightening torque; 15 KL external connection, 30 Ncm tightening torque; 15 Vega internal connection, 25 Ncm tightening torque; 15 Essential internal connection, 30 Ncm tightening torque. In each group removal torque values (RTV) were evaluated with a digital torque meter, in 3 distinct phases: after one single tightening, 10 multiple tightenings and 10 multiple tightenings and cyclic loading (500 N × 1000 cycles). Results: After one single tightening, and for all connections, RTV were lower than those of insertion, but only for Essential and Vega internal connections this result was statistically significant. After multiple tightening, RTV were significantly lower in all connections. After repeated tightening followed by cyclic loading, mean RTV were significantly lower, when compared to insertion torque. The multiple tightening technique resulted in higher RTV than the single tightening technique, except for Vega implant. The multiple tightening followed by cyclic load, compared to the other phases, was the one that generated the lowest RTV, for all connections. Conclusions: The connection design, in our study, did not seem to influence the maintenance of preload. Loading influenced the loss of preload, in the sense that significantly decreased the removal torque values. The multiple re-tightening technique resulted in higher removal torque values than the single tightening technique. Clinically, our results recommend to retighten retaining screws, a few minutes after insertion

Estudio del potencial de aprovechamiento de energía solar térmica en un cerramiento compuesto de ladrillo con material de cambio de fase

Con el aumento de las necesidades energéticas mundiales y la necesidad de cambiar el modelo energético actual por uno basado en las energías renovables, se hace patente la importancia de la eficiencia energética en todo tipo de procesos y, especialmente, en el sector doméstico a través de soluciones que reduzcan el consumo de energía en sistema de climatización, refrigeración o calefacción.Este estudio se centra en la implementación de materiales de cambio de fase (PCM) en paredes portantes de tubos de agua con la intención de almacenar energía térmica durante el día y ceder durante la noche el calor para calentar agua sanitaria. El objetivo principal es comprender el comportamiento térmico del PCM, cloruro de calcio hexahidratado, a través de la simulación numérica del sistema detallado. Además, dado que se requiere de una validación experimental para la ratificación de los resultados numéricos, se diseña el banco de ensayos que sirva para tal efecto, teniendo en cuenta la selección de los materiales y componentes necesarios para su construcción, el proceso de montaje y construcción y selección de la instrumentación, monitorización y control de forma que permitan reproducir las condiciones ambientales deseadas.Para la consecución de los resultados, se realiza una colaboración con el Dr. Lamine a través del cual se fijan las condiciones de contorno y la radiación solar incidente, 350W/m2. Además, se parte de un modelo numérico existen en el Grupo de Investigación GITSE del Departamento de Ingeniería Mecánica de la Universidad de Zaragoza que incluye la carga térmica del sistema a estudiar. Tras una recopilación bibliográfica sobre los PCMs y los antecedentes de estudios en cerramientos activos, se realiza la simulación de la descarga térmica del sistema junto a un análisis del efecto del caudal en el tiempo de descarga y en la variación de la temperatura del agua.En cuanto a la estructura del trabajo, se encuentra divido cinco capítulos. En el primero, se presentan los antecedentes de estudios en cerramientos activos y se plantea las condiciones del estudio. En el segundo de los capítulos, se presentan los objetivos a satisfacer a lo largo del escrito. En el tercer capítulo, se presenta el modelo numérico, se simula la descarga térmica del modelo y se analizan los resultados obtenidos y el efecto del caudal en el tiempo de descarga y la variación de la temperatura del agua. En el cuarto capítulo, se detalla el diseño del banco de ensayos en el que se realizarán los ensayos experimentales que permitirán la validación del modelo numérico. Finalmente, en el quinto capítulo, se ofrecen las conclusiones obtenidas y las líneas futuras del TFG. Además, se incluye un anexo con el marco teórico del almacenamiento energético térmico y de los PCMs.<br /

Estudio del potencial de aprovechamiento de energía solar térmica en un cerramiento compuesto de ladrillo con material de cambio de fase

Con el aumento de las necesidades energéticas mundiales y la necesidad de cambiar el modelo energético actual por uno basado en las energías renovables, se hace patente la importancia de la eficiencia energética en todo tipo de procesos y, especialmente, en el sector doméstico a través de soluciones que reduzcan el consumo de energía en sistemas de climatización, refrigeración o calefacción.Este estudio se centra en la implementación de materiales de cambio de fase (PCM) en paredes portantes de tubos de agua con la intención de almacenar energía térmica durante el día y ceder durante la noche el calor almacenado para calentar agua sanitaria. El objetivo principal es comprender el comportamiento térmico del PCM, cloruro de calcio hexahidratado (CaCl2·6H2O), a través de la simulación numérica del sistema detallado. Además, dado que se requiere de una validación experimental para la ratificación de los resultados numéricos, se diseña el banco de ensayos que sirva para tal efecto, teniendo en cuenta la selección de los materiales y componentes necesarios para su construcción, el proceso de montaje y construcción y la selección de la instrumentación, monitorización y control de forma que permitan reproducir las condiciones ambientales deseadas.<br /

Assessment of periapical status : a comparative study using film-based periapical radiographs and digital panoramic images

Aim: To compare the use of film-based periapical radiographs and digital panoramic images displayed on monitor and glossy paper in the assessment of the periapical status of the teeth. Methodology: A total of 86 subjects were examined. All participants underwent a full-mouth radiographic survey (14 periapical radiographs) and a digital panoramic radiography. The periapical status of all appraised teeth was assessed. Results: Periapical radiographs allowed the assessment of the periapical status of a significantly higher percentage of teeth (87.4%) Digital radiography had a significantly reduced potential to allow assessment of the periapical status (p<0.01). Only 58.0% and 34.3% of teeth could be appraised using digital panoramic images displayed on monitor and glossy paper respectively (p<0.01). The total percentage of teeth with periapical pathosis was four-fold higher when assessed with digital panoramic images displayed on glossy paper compared with periapical radiographs (p<0.01). Conclusions: Periapical radiographs allowed the assessment of a significantly higher percentage of teeth when comparing to digital radiography, which had a significantly lower potency in the assessment of periapical status of the teeth. Digital panoramic images displayed on a monitor resulted in a significantly higher percentage of appraised teeth compared to digital images displayed on glossy paper. Apical periodontitis was scored more often on paper than on screen, and more often on screen than in periapical radiographs

Resonance frequency analysis-reliability in third generation instruments : Osstell mentor ®

Few studies assess repeatability and reproducibility in registers of resonance frequency analysis (a value of dental implant stability). Objective: Few studies assess repeatability and reproducibility in resonance frequency analyses (implant stability evaluation). This study is aimed at assessing reliability (repeatabilty and reproducibility) in the Osstell Mentor® system using the intraclass correlation coefficient (ICC) as the statistical method. Study Design: ISQ measurements of RFA were carried out by means of the Osstell Mentor ® instrument in 58 implants in 19 patients. Six measurements were performed on each implant by means of two different Smart-Pegs (I and II). Three consecutive measurements were registered with each transducer. Results: Average ISQ varied from 72.43 to 72.60 and 73.26 in the first, second and third measurements, respectively with the SamrtPeg I and from 72.98 to 73.26 and 73.74 in the first, second and third measurements, respectively with the SamrtPeg II . Exactly equal values were observed in 10.43 and 12.1% of the cases with Smart-Pegs I and II, respectively. The intraclass correlation coefficient was 0.96 and 0.96 for Smart Pegs I and II, respectively. Repeatability and reproducibility was 0.97 for both Smart-Pegs I and II. Conclusions: The RFA system contributed by Osstell Mentor ® renders almost perfect reproducibility and repeatability, as proven by statistical analysis carried out by means of ICC with 95% confidence level. This instrument contributes highly reliable RFA measurements in dental implants

¿Pueden los factores clínicopatológicos mejorar la predicción de metástasis en ganglios linfáticos no centinelas en pacientes con cáncer de mama?

Introduction: To determine whether clinicopathological characteristics can improve the prediction of metastasis to nonsentinel lymph nodes (NSLNs) over the use of only mRNA copy number in sentinel lymph node (SLN) biopsies. Methods: This was a retrospective, observational study that included a total of 824 patients with T1-3 breast cancer who had clinically negative, ultrasound-negative axilla without evidence of metastasis and who underwent one-step nucleic acid amplification in SLN biop-sies. Results: 118 required a complete axillary lymph node dissection (ALNhD). About 35.6% (42/118) had metastases to a NSLN, and 64.4% (76/118) had no metastasis to a NSLN. The ROC curve of the total tumor load (TTL) presented an area under the curve (AUC) of 0.651 (95%; CI: 0.552-0.751). The 7294 copies of CK19 mRNA were established as the optimal cutoff point, with sensitivity: 93%, specificity: 63%, positive predictive value: 44%, and negative predictive value: 91%. By as-sociating the clinicopathological parameters (multicentricity, pooled immunohistochemistry [IHC], and progesterone receptors), the AUC went up to 0.752 (95% CI: 0.663-0.841). Conclusions: Clinicopathological factors should be considered together with the total CK19 mRNA copy number (the TTL) of the SLNs to improve the predictive capacity of metastatic involvement of the NSLNs

Dental audit (I) : exact criteria of dental records; Results of a Phase-III study

Objective: Evaluating the quality of dental records in the Faculty of Dentistry of the University of Seville (Spain). We attempted to collect and/or develop identifiable elements of dental care used to evaluate its appropriateness, as well as to measure its level of filling-in between 1999 and 2004 (Phase III of the record audit). Method: The 46 criteria used to evaluate dental care are shown, measuring ?in 50 dental records randomly chosen within a 5-year-time period? their level of filling-in (Phase III of a health audit). Results: A low level of filling-in was observed in all quality criteria defined. No record was found to be free from errors. A maximum of 36 criteria out of 46 was fulfilled (mean of 20.8). Conclusions: The standard of appropriate filling-in was only met in 12 criteria (75 %), the results being poor, due to the importance which clearly deficient aspects related to diagnosis and treatment plan have in the process of patient care. For such reason, we suggest a remedial action (Phase IV) developing a new model of dental record and its subsequent re-evaluation (Phase V), which will be subject to analysis in the second part of this paper

Audit of dental reports (II) : first Phase-II study in a Spanish Faculty of Dentistry

As a measure for correction of deficiencies registered through an audit of dental records in the Comprehensive Dentistry Clinic of the Dentistry Faculty of the University of Seville, we elaborated a new format for dental records which was used in 70 patients, carrying out a monitoring audit (Phase V) by applying the same quality criteria and criteria for data collection used in the initial audit (Phase III). We calculated the indices of fulfilment of 46 quality criteria, extending fulfilment percentage to 41 criteria, while statistically significant differences were found in 25 criteria. The standard prefixed as appropriate (75 %) was reached in 29 criteria (against the 12 criteria in which such standard was reached in the first dental audit). It is essential that faculties of dentistry develop systems for dental record revision which may help students achieve the competence of registering dental-care steps appropriately, teachers identify and give response to educational problems, and clinic administration prevent and correct conflicts, at the same time that they all ensure quality in service provision, ease relations with customers and protect users against legal vulnerability

Height difference between the vestibular and palatal walls and palatal width: a cone beam computed tomography approach

Background: The objective of this study was to measure two parameters involved in tri-dimensional implant plan‑ ning: the position of the buccal and palatal bone wall and the palatal thickness. Methods: Cone beam computed tomography (CBCT) images (Planmeca ProMax 3D) of 403 teeth (208 upper teeth and 195 lower teeth) were obtained from 49 patients referred to the Dental School of Seville from January to Decem‑ ber 2014. The height diference between the palatal and buccal walls was measured on the most coronal point of both walls. The thickness of the palatal wall was measured 2 mm from the most coronal point of the palatal wall. Results: The mean values in the maxilla were 1.7±0.9 mm for central and lateral incisors, 2.2±1.7 mm for canines, 1.6±0.9 mm for premolars and 1.9±1.5 mm for molars. In the lower jaw, the mean values were 1.3±0.8 mm for inci‑ sors, 1.7±1.2 mm for canines, 2.3±1.3 mm for premolars, and 2.6±1.7 mm for molars. In the upper jaw, more than 55% of maxillary teeth (excluding second premolars and molars) presented mean height diferences greater than 1 mm. In the mandible, more than 60% of incisors showed a buccal bone thickness of 1 mm from the apical to lingual aspect. All teeth except the second premolar presented a buccal wall located more than 1 mm more apically than the lingual bone wall. Conclusions: The buccal bone wall is located more apically (greater than 1 mm) than the palatal or lingual table in most of the cases assessed. The thickness of the palatal or lingual table is also less than 2 mm in the maxilla and man‑ dible, except in the upper canines and premolars and the lower molars