In the current orthodontic and prosthodontics practice, study models made of plaster are being used to provide a three-dimensional view of the patient’s occlusion and allow the clinician to analyze, diagnose, or monitor anomalies. With the introduction of intraoral and extra oral digital impressions, it is now possible to obtain digital study models of the patients’ dental arches. Digital models can be obtained in a physical hardcopy via 3D printing or rapid prototyping. Although, professional 3D printers require a high initial set-up cost, low cost 3D printers can provide similar quality products. The aim of this study is to investigate the accuracy of physical dental models reconstructed from digital data by two rapid prototyping techniques. For this purpose twenty mandibular and maxillary conventional plaster models from randomly chosen subjects were selected and served as the gold standard. The casts were digitized using a 3D scanner and .stl surface models were acquired; the virtual model was adjusted for reconstruction using dedicated software, thus obtaining the CAD model of the casts. The CAD models were reconstructed using a 3D fused deposition modeling (FDM) printer, a RepRap FDM printer and an inverted stereolithography printer. The reconstructed models were digitized using a laboratory 3D scanner and the resulting Mesh datasets were compared with the CAD model using inspection software. The mean systematic differences for the 3D comparison of the reconstructed models were 0.207 mm for the stereolithography models, 0.156 mm for the FDM models, and 0.128 mm for the RepRap models. Although a technology proved the ability to manufacture a dental model with accentuated morphology, the results demonstrate that replicas of plaster casts are influenced by problems linked to the size of the detail to be reproduced, which is often similar to or finer than the fabrication layer.
This study examined and compared surface of human dentine after acidic etching with hydrogen peroxide, phosphoric acid liquid and gel. Surface demineralization of dentin is necessary for a strong bond of adhesive at dental surface. Split human teeth were used. After application of mentioned substances at dentin level measures of the contact angle and surface morphology were employed. Surface morphology was analyzed with the help of scanning electron microscopy and atomic force microscopy. Liquid phosphoric acid yielded highest demineralization showing better hydrophobicity than the rest, thus having more contact surface. Surface roughness are less evident and formed surface micropores of 4 �m remained open after wash and air dry providing better adhesive canalicular penetration and subsequent bond.
The replacement of classical fillings, especially in the posterior area with different types of inlays has become a common solution used in order to improve all parameters which insure a long lasting treatment. Vrious ceramic materials and systems are available, but so far an ideal ceramic material suited for all clinical situations, has not been found. The range of ceramic materials as: lithium disilicate, aluminum oxide, zirconium oxide and hybrid ceramics enhance the possibilities of using ceramic inalys in various clinical situations. Marginal adaptation is one of the most important conditions for long-term success for any type of material. The marginal discrepancy of fixed restorations is one of the main factors which lead to failure of the prosthetic treatment.The purpose of the present study is to compare a 2D and 3D method for evaluating the marginal fit for pressed lithium dislicate inlays (Emax). The two used methods were: SEM- electronic microscopy and micro CT.
Periodontitis (PO), a chronic microbially-induced inflammation of the supporting tissues of the tooth, is linked to various systemic diseases. We analyze its bidirectional relationship to chronic kidney disease (CKD), a major health-care problem with impressive excess mortality. Overwhelming associative relationship between CKD and PO are analyzed. Major pathophysiologic mechanisms that link CKD to PO are then presented: systemic inflammation, endothelial dysfunction, and imbalance of oxidative stress characteristic of CKD have a role in PO development and might influence escape mechanisms of oral microbiota. Subclinical local and systemic inflammation induced by PO might influence in turn CKD outcomes. Homeostatic changes induced by CKD such as mineral bone disorders, acidosis, uremic milieu, or poor salivary flow are also relevant for the occurrence of PO. There is insufficient evidence to recommend a standardized diagnostic and therapeutic approach regarding association of PO to CKD.
The main goal of the present study is to compare the marginal fit of two different kind of pressed materials: a partially crystalline thermoplastic resin reinforced with ceramic particles (BioHPP) and lithium disilicate (EMax), through the use of the microCT technique. After extraction of four caries-free mandibular first molars, first class inlay cavities were prepared. For each tooth two inlays were manufactured- one by using BioHPP thermoplastic resin (n=4) and one by using Emax Press lithium disilicate (n=4). The marginal gap was analyzed circumferentially at the occlusal margin using a Bruker micro CT, by measuring the distance at the occlusal limit of the cavities, between the restoration and the tooth in several points for every surface of each tooth before cementing. Data were analyzed statistically using the Mann-Whitney U test and the Pearson�s correlation coefficient (a=0.05). A significant statistical difference was found between the marginal gap size obtained for BioHPP and Emax inlays (p[0.001). For the Emax inlays the marginal gap had an average of 72mm, while for BioHPP the average was 94 �m. Both types of used materials offer a good marginal adaptation. By summing up the gathered data we can conclude that the pressed ceramics shows a better marginal fit than the pressed resin, probably because of the different processing methods: sintering versus polymerizing with different shrinkage values.
The goal of the present study is to compare the marginal fit using microCT of ceramic inlays obtained using two different technologies: pressing technique (lithium disilicate) and milling technique (milled leucite glass-ceramic). After extraction of four caries-free mandibular first molars, first class inlay cavities were prepared. For each tooth two inlays were manufactured- one by using pressed lithium disilicate (Emax) (n=4) and one by using milled leucite glass-ceramic (n=4). The marginal gap was analyzed circumferentially at the occlusal margin using a table-top Bruker micro CT, by measuring the distance at the occlusal limit of the cavities, between the restoration and the tooth in several points for every surface of each tooth before cementing. Data were analyzed statistically using One �way ANOVA with Tukey�s Multiple Comparison Test performed using 5.00 for Windows (GraphPad Prism 5.00 Software, San Diego, California USA). When the marginal gaps of the inlays made out of different materials on the same tooth were compared, only one result had no statistical significance. The program expressed also results by comparing the gaps of pressed vs milled restorations on different teeth. 11 out of 16 results had statistical significance. Although statistical significance between the two studied materials, we can conclude that both used materials offer a good marginal adaptation within the acceptable limits. By summing up the gathered data we can conclude that the milled ceramic shows a better marginal fit than the pressed ceramic.
This experimental study aims to highlight and compare the resolution and accuracy (trueness and fidelity) of an intraoral scanner and a laboratory scanner. In order to achieve the aim of this study, an experimental model consisting of a die with a standard preparation for a porcelain-fused to metal crown was manufactured from a physiognomic polymethylmethacrylate resin. The experimental model was scanned with an industrial CT to obtain the virtual reference model. Then, the die was scanned 15 times with each scanner. In order to asses trueness, comparisons were made with the virtual reference model, and for fidelity, the first scan in the series was compared with the following scans. In regards to the trueness of the scanners, the average deviation for the laboratory scanner is 4.31 and 17.34 mm for the intraoral scanner. When comparing the serial scannings� of the same die, the lowest recorded deviation is 6.4 mm for the laboratory scanner and 21.57mm for the intraoral scanner. For both fidelity and trueness, the F test demonstrates that there is a statistically significant difference between the scanners and the applied T-tests confirm the lower degree of error-rate generation by the laboratory scanner. The dimensional limitations imposed for the intraoral scanners have a direct consequence on their trueness and fidelity when compared to their laboratory counterparts.
The objective of this in-vitro study was to compare the accuracy, defined as trueness and precision, of two intraoral digital scanners that use different capturing techniques. An experimental reference object consisting of a die was manufactured from a PMMA resin. The reference object was digitized with an industrial CT and was scanned 15 times with each scanner. In order to asses trueness, comparisons were made with the virtual reference model, and for fidelity, the first scan in the series was compared with the following scans. For both fidelity and trueness, the F test and T tests demonstrate that there is a statistically significant difference between the scanners.
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