ABSTRACT
The aim is to investigate the premature catastrophic fracture produced for different periods during clinical endodontic treatment of two brands of NiTi endodontic rotary instruments. 3 samples as-received, 6 samples used with patients for 2 and 7 h and 5 samples fractured were studied for each brand of endodontic NiTi rotary instruments. Transformation temperatures (Ms, Mf, As and Af) and enthalpies of transformation were determined by calorimetry. Critical stresses until fracture (σßâSIM, σSIMâß) were obtained using an electromechanical testing machine. The samples were also visualized by Scanning Electron Microscopy. Calorimetric studies have shown an increase of the Ms and As transformation temperatures with time of use as well as a decrease of their stress transformations. Moreover, reverse transformation enthalpies decreased along the time. The enthalpies of transformation decreased because martensitic plates were anchored, which prevented their transformation to austenite; thus losing its superelastic effect. The stabilisation of the martensitic plates induced the collapse of the structure and so the main cause for the fracture. The heat treatment proposed has been increased the life in service of NiTi superelastic endodontic instruments recovering theirs superelastic effect.
Subject(s)
Alloys/chemistry , Dental Instruments , Biocompatible Materials , Humans , Materials Testing , Temperature , ThermodynamicsABSTRACT
This study focuses on the fatigue behavior and bone-implant attachment for the more usual surfaces of the different CP-titanium dental implants. The implants studied were: as-received (CTR), acid etching (AE), spark-anodization (SA), and with a grit-blasted surface (GB). Residual stresses were determined by means of X-ray diffraction. The fatigue tests were carried out at 37°C on 160 dental implants, and the stress-failure (S-N) curve was determined. The fatigue tests showed that the grit-blasting process improved fatigue life. This is a consequence of the layer of compressive residual stresses that the treatment generates in titanium surfaces. Further, our aim was to assess and compare the short- and midterm bone regenerative potential and mechanical retention of the implants in bone of New Zealand rabbits. The mechanical retention after 4 and 10 weeks of implantation was evaluated with histometric and pull-out tests, respectively, as a measure of the osseointegration of the implants. The results demonstrated that the GB treatment produced microrough that accelerated bone tissue regeneration and increased mechanical retention in the bone bed at short periods of implantation in comparison with all other implants tested. The GB surface produced an improvement in mechanical long-time behavior and improved bone growth. These types of treated implants can have great potential in clinical applications, as evidenced by the outcomes of the current study.
Subject(s)
Dental Implants , Osseointegration , Stress, Mechanical , Animals , Bone Regeneration , Rabbits , Surface Properties , TitaniumABSTRACT
OBJECTIVE/INTRODUCTION: Unemployment can negatively impact quality of life among patients with schizophrenia. Employment status depends on ability, opportunity, education, and cultural influences. A clinician-rated scale of work readiness, independent of current work status, can be a valuable assessment tool. A series of studies were conducted to create and validate a Work Readiness Questionnaire (WoRQ) for clinicians to assess patient ability to engage in socially useful activity, independent of work availability. METHODS: Content validity, test-retest and inter-rater reliability, and construct validity were evaluated in three separate studies. RESULTS: Content validity was supported. Cronbach's α was 0.91, in the excellent range. Clinicians endorsed WoRQ concepts, including treatment adherence, physical appearance, social competence, and symptom control. The final readiness decision showed good test-retest reliability and moderate inter-rater reliability. Work readiness was associated with higher function and lower levels of negative symptoms. Low positive and high negative predictive values confirmed the concept validity. DISCUSSION: The WoRQ has suitable psychometric properties for use in a clinical trial for patients with a broad range of symptom severity. The scale may be applicable to assess therapeutic interventions. It is not intended to assess eligibility for supported work interventions. CONCLUSIONS: The WoRQ is suitable for use in schizophrenia clinical trials to assess patient work functional potential.
Subject(s)
Employment/psychology , Patient Compliance , Physical Appearance, Body , Schizophrenia , Schizophrenic Psychology , Social Skills , Adult , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Psychometrics , Reproducibility of Results , Surveys and Questionnaires , Work/psychologyABSTRACT
OBJECTIVE: The objective of this study was to evaluate the osseointegration and crestal bone loss (CBL) in two implant designs with different diameters (Mini Sky® and Narrow Sky®) implants, placed at different vertical levels at healed canine ridges. MATERIAL AND METHODS: The second, third, and fourth mandibular premolars of six Beagle dogs were extracted bilaterally. After 2 months healing, four implants divided into two groups according to their diameters (i.e., Narrow Sky® and Mini Sky®) were placed in each hemi-mandible at the level of the bone crest or 2 mm subcrestally. The animals were euthanized at 12 weeks and undecalcified samples were processed for histology. Histomorphometric analysis was carried out to compare bone-to-implant contacts (BIC) and crestal bone loss (CBL). RESULTS: There were not significant differences in CBL between groups when the implants were placed at subcrestal bone level (p > 0.05), meanwhile the CBL was significantly higher for both groups when the implants were inserted at crestal level (p < 0.05). All implants were osseointegrated presenting a minimum BIC percentage of 56%. The major percentages of BIC were found for both groups at subcrestal level (p < 0.05). CONCLUSIONS: Within the limitations of this experimental study may be concluded that the implant diameter does not affect the CBL. BIC values are affected by implant diameter and design been higher for narrow implants compared to mini-implants. Subcrestal insertion of both implants favors crestal bone preservation but crestal insertion of both designs is associated with crestal bone loss CLINICAL RELEVANCE: The study shows that narrow implants protect peri-implant crestal bone.
Subject(s)
Alveolar Bone Loss/pathology , Dental Implantation, Endosseous/methods , Dental Implants , Dental Prosthesis Design , Animals , Bicuspid , Dogs , Female , Mandible/pathology , Mandible/surgery , Osseointegration/physiology , Surgical FlapsABSTRACT
La utilización de los implantes oseointegrados para restaurar a los pacientes edéntulos se ha incrementado en la práctica general. Lasuperficie de los implantes es muy importante para conseguir la oseointegración. Existen muchos tipos de superficies en los implantes dentales. La investigación en superficie de implantes comienza con la superficie mecanizada. La superficie rugosa incrementa la adherencia celular y muestra una mayor área de contacto hueso-implante. El recubrimiento con plasma de titanio e hidroxiapatita fueron métodos comunes para modificar la rugosidad de la superficie. Más recientemente, el chorreado con partículas (ej. alúmina, óxido de titanio) de diferentes diámetros y el grabado ácido (ej. chorhídrico, sulfúrico, nítrico) son otros procesos que pueden incrementar la superficie rugosa de los implantes. El tratamiento de la superficie de los implantes constituye un importante campo en futuras investigaciones de la implantología oral (AU)
Use of osseointegrated implants to restore edentulous patients has increased in the general dentistry. Implant surface is very important for enhance osseointegration. They are many types of dental implant surfaces. Implant surface research begins with machined or turned surface. Roughened surface titanium increase cell adhesion and exhibit stronger bone-implant contact area. Plasma-spray and hydroxyapatite coating were common methods for rough surface modification. Most recently, blasting with particles (i.e. aluminium, titanium oxide) of various diameters and chemical acid-etching(i.e. hydrochloric, sulphuric and nitric acids) are another process by which surface roughness can be increased. The surface modifications of titanium constitute an important field for future research of implant dentistry (AU)
Subject(s)
Humans , Dental Implantation, Endosseous/methods , Mouth, Edentulous/surgeryABSTRACT
Actualmente, la investigación en las superficies de los implantes es un importante campo de la implantología oral. La superficie tratada con láser puede incrementar la adhesión osteoblástica e impulsar la oseointegración. El zirconio es un nuevo material cerámico para los implantes dentales. Las superficies rugosas por chorreado y/o grabado ácido pueden ser bioactivadas con diferentes sustancias (factores de crecimiento, PGRF; fluoruros; proteínas morfogenéticas, BMP-2; melatonina; estatinas) que constituyen otras formas de mejorar la oseointegración. Más recientemente, la tecnología de las nano estructuras ha comenzado en la implantología oral con el desarrollo de superficies nanoporosas que manifiestan una mejor respuesta osteogénica e incrementa la unión mecánica hueso-titanio. La incorporación de nuevos materiales y procesos técnicos en la investigación sobre superficies de implantes ofrecen nuevas posibilidades de mejorar su respuesta tisular y su potencial regenerativo óseo (AU)
Today, implant surface research is a very important field of implant dentistry. Surface treated with laser may increase osteoblast adhesion and enhance osseointegration. Zirconia is a new ceramic material for dental implants. Blasted and acid roughened implant surfaces may be bioactived with different substances (growth factors, PRGF; fluoride; morphogenetic proteins, BMP-2; melatonin, statines) that constitute another ways of improve the osseointegration. Mostrecently, nanostructuring technology begins in implant dentistry with the development of nanoporous surfaces that manifest better osteogenic response and increase bone-titanium mechanical interlocking. The introduction of new materials and new technical process in dental surfaces research offering new possibilities for better tissue response and bone regenerative potential (AU)
Subject(s)
Humans , Dental Implantation, Endosseous/methods , Mouth, Edentulous/surgery , Dental Materials , CeramicsABSTRACT
Late-life depression (LLD) initially occurs after age 65 and is a major public health concern because elderly people who are at high risk constitute an ever-expanding segment of the population. LLD is a mental illness in which mood, thought content, and behavioural patterns are impaired, causing individual distress, compromising social function and impairing self-maintenance skills (e.g. bathing, dressing, hygiene). It is characterised by marked sadness, or a loss of interest or pleasure in daily activities and may be accompanied by weight change, sleep disturbance, fatigue, difficulty concentrating, and high suicide rate. Individuals under treatment for LLD and those whose illness has not been diagnosed or treated often present to the dentist with significant oral disease. LLD is frequently associated with a disinterest in performing oral hygiene, a cariogenic diet, diminished salivary flow, rampant dental decay, advanced periodontal disease, and oral dysesthesias. Many medications used to treat the disease magnify the xerostomia and increase the incidence of dental disease. Appropriate dental management necessitates a vigorous preventive dental education programme, the use of artificial salivary products, antiseptic mouthwash, daily fluoride mouthrinse and special precautions when administering local anaesthetics with vasoconstrictors and prescribing analgesics.