ABSTRACT
This study aimed to evaluate the erosive potential of powdered juice drinks on dental enamel in 2 stages: physiochemical characterization and erosive challenge testing. In stage 1, the pH and titratable acidity of 5 commercially available powdered juices in 10 different flavors were analyzed. Five treatment groups were then established based on the pH values, titratable acidity, and presence of citric acid in the juices, and their energy-dispersive X-ray (EDX) spectroscopy profiles were studied. In stage 2, the erosive effect of the juices was tested using a pH cycling model; polished bovine dental enamel blocks (n = 8) were treated 4 times daily on 5 consecutive days with 1% citric acid (positive control) or lemon, orange, pineapple, or cashew juice. The specimens were immersed in the erosive solutions, under agitation (100 rpm), for 1 minute at 25°C. Overnight and between treatments, the blocks were stored in artificial saliva without agitation. At the end of cycling, the enamel surfaces were evaluated by profilometry and scanning electron microscopy. The stage 2 results were submitted to 1-way analysis of variance followed by Tukey test (α = 0.05). The pH values of the juices ranged between 2.86 (lemon) and 3.84 (cashew), while the titratable acidity ranged from 14.5 (cashew) to 90.00 (lemon) mmol/L. Lemon juice showed the least calcium content (2.76%) and no (0.00%) phosphorus concentration. Orange, pineapple, and cashew juices showed the greatest concentrations of calcium and phosphorus and were therefore less erosive than lemon juice. The mean [SD] surface loss was higher in the lemon juice group (0.52 [0.16] µm), with no significant differences (P > 0.05) from the control (0.39 [0.09] µm) and orange juice (0.41 [0.12] µm). In groups exposed to pineapple juice (0.36 [0.04] µm) and cashew juice (0.16 [0.08] µm), the surface loss was significantly lower (P < 0.05) than that found in lemon juice. The results demonstrate that powdered juice drinks (especially lemon juice) present erosive potential and lead to surface loss of dental enamel.
Subject(s)
Citrus sinensis , Tooth Erosion , Animals , Beverages , Cattle , Dental Enamel , Hydrogen-Ion Concentration , Powders , Tooth Erosion/chemically inducedABSTRACT
PURPOSE: To verify the influence of computer-aided design/computer-aided manufacturing (CAD/CAM) implant-supported prostheses manufactured with cobalt-chromium (Co-Cr) and zirconia (Zr), and whether ceramic application, spark erosion, and simulation of masticatory cycles modify biomechanical parameters (marginal fit, screw-loosening torque, and strain) on the implant-supported system. MATERIALS AND METHODS: Ten full-arch fixed frameworks were manufactured by a CAD/CAM milling system with Co-Cr and Zr (n=5/group). The marginal fit between the abutment and frameworks was measured as stated by single-screw test. Screw-loosening torque evaluated screw stability, and strain analysis was explored on the implant-supported system. All analyses were performed at 3 distinct times: after framework manufacturing; after ceramic application in both materials' frameworks; and after the spark erosion in Co-Cr frameworks. Afterward, stability analysis was re-evaluated after 106 mechanical cycles (2 Hz/150-N) for both materials. Statistical analyses were performed by Kruskal-Wallis and Dunn tests (α=.05). RESULTS: No difference between the two materials was found for marginal fit, screw-loosening torque, and strain after framework manufacturing (P>.05). Ceramic application did not affect the variables (P>.05). Spark erosion optimized marginal fit and strain medians for Co-Cr frameworks (P<.05). Screw-loosening torque was significantly reduced by masticatory simulation (P<.05) regardless of the framework materials. CONCLUSION: Co-Cr and Zr frameworks presented similar biomechanical behavior. Ceramic application had no effect on the biomechanical behavior of either material. Spark erosion was an effective technique to improve Co-Cr biomechanical behavior on the implant-supported system. Screw-loosening torque was reduced for both materials after masticatory simulation.
ABSTRACT
Aim: The aim of this study was to investigate the biomechanical behavior of implant-retained mandibular overdentures using Micro ERA® system with different implant position and angulation by finite element analysis (FEA). Methods: Four 3D finite element models of simplified mandibular overdentures were constructed, using one Bränemark implant with a Micro ERA® attachment. The implant was positioned on the canine or lateral incisor area with an angulation of either 0º (C-0º; LI-0º) or 17º (C-17º, LI-17º) to the vertical axis. A 100 N axial load was applied in one side simultaneously, from first premolar to second molar. In all models it was analyzed the overdenture displacement, compressive/tensile stress in the bone-implant interface, and also the von Mises equivalent stress for the nylon component of the housing. The stresses were obtained (numerically and color-coded) for further comparison among all the groups. Results: The displacement on the overdenture was higher at the posterior surface for all groups, especially in the C-17º group. When comparing the compressive/tensile stress in the bone-implant interface, the lateral-incisor groups (LI-0º and LI-17º) had the highest compressive and lowest tensile stress compared to the canine groups (C-0º and C-17º). The von Mises stress on the nylon component generated higher stress value for the LI-0º among all groups. Conclusions: The inclination and positioning of the implant in mandibular overdenture interferes directly in the stress distribution. The results showed that angulated implants had the highest displacement. While the implants placed in the lateral incisor position presented lower compressive and higher tensile stress respectively. For the attachment the canine groups had the lowest stress
Subject(s)
Dental Implants , Finite Element Analysis , Denture, OverlayABSTRACT
Introdução: Quando existe perda de suporte coronário e ainda desgaste adicional devido a tratamento endodôntico, muitas vezes, é necessária a utilização de um retentor intrarradicular que devolva a retenção para a restauração, reestabelecendo estética e função às estruturas dentárias perdidas. A cadeia asséptica mantida durante a endodontia pode ser quebrada com alguns procedimentos clínicos. Objetivo: Testar um protocolo de desinfecção por E. faecalis dos condutos radiculares, nas etapas de confecção de um retentor intrarradicular, desmistificando que a quebra da cadeia asséptica e o surgimento de infecções radiculares sejam provenientes da reabilitação protética. Material e método: 50 dentes unirradiculares com endodontia concluída foram desobturados, tiveram seus condutos preparados para retentor intrarradicular e foram contaminados por Enterococcus faecalis. Os dentes foram separados em três grupos de acordo com a substância desinfectante: G1-solução fisiológica (n=10), G2- hipoclorito de sódio 2,5% (n=20), G3- clorexidina 2% (n=20). Em seguida, foi feita a desinfecção do conduto, secagem e análise da eficácia da solução. A avaliação da presença da bactéria foi feita através do cultivo em caldo Brain Heart Infusion, pelo método da turvação, e posterior identificação pelo meio Ágar Bílis-Esculina. A análise estatística foi feita pelo método do quiquadrado em tabulação cruzada, onde p<0,0001. Resultado: Observou-se a inibição bacteriana de 100% em G2 e G3 e crescimento bacteriano de 100% em G1. Conclusão: O emprego das substâncias avaliadas nas etapas protéticas de finalização de um retentor intrarradicular, como protocolado por esta pesquisa, é capaz de manter a cadeia asséptica sem interferir no sucesso da reabilitação protética.
Introduction: When there is loss of the coronary supports and still further wear due to endodontic treatment, very often, it is necessary to use a intraradical retainer to restore aesthetics and function of lost dental structures. Within this rehabilitation, the aseptic chain which was maintained during endodontics can be broken using some clinical procedures. Aim: Test a disinfection protocol by E. faecalis of root canals, in the steps of making an intraradicular retainer, demystifying that the fracture of the aseptic chain and the emergence of root infections are coming from prosthetic rehabilitation. Materials and method: 50 single-rooted teeth with complete endodontics were unfilled, they had their conduits prepared for an intraradical retainer and contaminated by Enterococcus. faecalis. The teeth were divided into 3 groups according to the disinfectant solution. G1- saline (n= 10), G2 2.5% sodium hypochlorite (n=20), G3- chlorhexidine 2% (n=20). Then, a disinfection of conduit, drying and analysis of the efficacy of the solution was made. The evaluation of the presence of Enterococcus faecalis was made by cultivating in Brain Heart Infusion broth by the method of turbidity, and subsequent identification by means Agar Bile-Esculin. Statistical analysis were performed using the chi-square method in cross-tabulation, where p <0.0001. Result: As a result, it was observed 100% bacteria inhibition in G2 and G3, and bacterial growth of 100% in G1. Conclusion: The use of substances assessed in the prosthetic stages of finalizing an intraradical retainer, as filed by this research, is able to maintain the aseptic chain without interfering with success of prosthetic rehabilitation.
