Search results for "UNESCO::CIENCIAS MÉDICAS"
showing 10 items of 6828 documents
Repeated exposure of acidic beverages on esthetic restorative materials: An in-vitro surface microhardness study.
2015
Background A manifold increase in the consumption of aerated beverages has witnessed a twin increase in tooth wear and raised demand for esthetic restorative materials. This study aimed to evaluate the surface microhardness changes of esthetic restorative materials following treatment with aerated beverages in an in-vitro situation. Material and Methods The initial surface microhardness of the restorative materials GC Fuji II LC, GC Fuji IX, Nano Glass ionomer, Resin and Nano composite was recorded. These materials were studied under 3 groups that included those exposed to the acidic beverages daily, weekly once in a month and those that had no exposures at all. The final surface microhardn…
Effect of different solutions in reversing the damage caused by radiotherapy in dentin structure
2020
Background Previous studies have shown that radiotherapy of the head and neck region can cause direct changes in dental structure. This study evaluated the effect of different solutions on the dentin chemical composition and collagen structure of irradiated dentin. Material and Methods Sixty maxillary canines were distributed in 2 groups (n=30): non-irradiated and irradiated (radiotherapy: X-rays of 6 MV in 30 cycles of 2 Gy to 60 Gy). The teeth were sectioned, sanded, and polished to obtain 3x3x2 mm fragments, which were redistributed in 3 subgroups (n=10) according to the treatment employed: chlorhexidine 2% (CL), chitosan 0.2% (QT), and 0.5 M carbodiimide (EDC). The samples were analyzed…
An in vitro cyclic fatigue resistance comparison of conventional and new generation nickel-titanium rotary files
2018
Background New designs and processing of Niquel-Titanium (NiTi) have been introduced to increase resistance to cyclic fatigue. The purpose of this study was to compare the cyclic fatigue resistance of 3 NiTi rotary instruments, ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Profile Vortex Blue (PVB; Dentsply Tulsa Dental, Tulsa, OK, USA) and ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland). Material and Methods A cyclic fatigue test was conducted operating instruments from ProTaper Next X2, Profile Vortex Blue 25.06 and ProTaper F2. A total of 234 instruments were rotated in 2 simulated stainless steel curved canals with different angles of curvature …
Effect of various dentin disinfection protocols on the bond strength of resin modified glass ionomer restorative material.
2017
Background Disinfection of dentin surface prior to any restorative therapy is important for the longevity of the treatment rendered. However, these dentin disinfection methods should itself not interfere with the adhesion of the restorative material. Therefore the aim of this study was to determine the effect of various dentin disinfection protocols on the shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC). Material and methods The occlusal surface of 40 extracted premolars were trimmed to obtain a flat dentinal surface and was randomly divided into four groups. CTRL was the control group; NaOCl was 1% sodium hypochlorite disinfection group; CHX was 2% chlorhexidine di…
Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: an i…
2016
Background: Different in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets. Material and Methods: 120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate th…
Clinical effect of diode laser on peri-implant tissues during non-surgical peri-implant mucositis therapy: Randomized controlled clinical study
2019
Background: The aim of this study is to evaluate the response to the non-surgical treatment of peri-implant mucositis using the diode laser as an adjuvant therapy in patients with implant-supported restorations, in terms of clinical variables, with respect to those patients in whom conventional non-surgical therapy is used. Material and Methods: Randomized controlled clinical trial with simple blind 3 months follow-up. Two groups of patients were established, the non-surgical mechanical debridement of the affected implants was performed in the control group (n = 34) and the diode laser therapy was also performed in the test group (n = 34). The implant was considered the study subject; the v…
The effect of photodynamic therapy and polymer solution containing nano-particles of Ag /ZnO on push-out bond strength of the sealers AH-Plus and MTA…
2017
BACKGROUND The aim of this in vitrostudy was to examine and compare the effect of photodynamic therapy and solution containing nano particles Ag/ZnO on adhesion of endodontic sealers to dentinal walls of human root canal. MATERIAL AND METHODS Ninty single-rooted human teeth were selected and their clinical crown was cut from the cemento-enamel junction zone. Canals were prepared by RaCe rotary system and the smear layer was removed using 17% EDTA and 5.25% NaOCl. Samples were randomly divided into two groups of AH Plus and MTA Fillapex based on the sealer type and each group based on antimicrobial method was divided into two sub-groups of photodynamic therapy and polymer containing nano par…
Effect of in-office bleaching gels with calcium or fluoride on color, roughness, and enamel microhardness
2019
Background Commercial bleaching gels with remineralizing agents were developed to reduce the adverse effects of dental bleaching. The present study evaluated the effects on teeth of in-office bleaching gels containing 35-40% hydrogen peroxide (HP) with Calcium (Ca) or Fluoride (F). Material and methods Bovine enamel/dentin blocks (4x4x2.5 mm) were randomly divided into the following groups (n=12): no treatment (control); 35% HP (Whiteness HP, FGM); 35% HP with Ca (Whiteness HP Blue, FGM); 40% HP with F (Opalescence Boost, Ultradent). The specimens were analyzed for color (ΔL*, Δa*, Δb*, and ΔE), roughness (Ra), and Knoop microhardness (KHN). The color and KHN data were submitted to ANOVA an…
Extensive osteonecrosis of the maxilla caused by bisphosphonates: Report of a rare case
2019
Bisphosphonates are drugs indicated for the treatment of bone metabolic diseases or malignant hypercalcemia. They are generally well-tolerated drugs, however, recent reports have described osteonecrosis of the jaw bones as a potentially serious complication related to the long-term use of these drugs. We report a case of severe osteonecrosis in a 52-years-old white woman that was taking bisphosphonates (zoledronic acid and alendronate) for the management of osteoporosis. Following a long exposure to these drugs and after being subjected to multiples exodontias, developed bisphosphonate-related osteonecrosis of the jaw compromising the whole maxilla and that extended toward the base of skull…
Evaluation of Antibacterial Efficacy of Photodynamic Therapy vs. 2.5% NaOCl against E. faecalis-infected Root Canals Using Real-time PCR Technique
2017
Background Bacteria like E. faecalis can produce intra- and extra-radicular biofilms. Theoretically, the adjustable penetration ability of lasers enables better access to root canal system. Therefore the aim of the present study was to compare the ability of photoactivated laser and 2.5% NaOCl irrigation solution to eliminate E. faecalis from the root canals by real-time PCR technique. Material and methods Sixty extracted human upper central incisors were selected and sterilized in an autoclave. The root canals were infected with E. faecalis (PTCC 1237, Persian Type Culture Collection, Iran) and then incubated for 24 hours. The samples were randomly divided into 3 groups. No intervention wa…