scholarly journals Parameters Affecting the Retention Force of CAD/CAM Telescopic Crowns: A Focused Review of In Vitro Studies

2021 ◽  
Vol 10 (19) ◽  
pp. 4429
Author(s):  
Abdullah Kamel ◽  
Amr Badr ◽  
Gehan Fekry ◽  
James Tsoi

Telescopic systems constructed using computer aided design and computer aided manufacture (CAD/CAM) can overcome many drawbacks associated with conventionally constructed ones. Since retention is considered the most important function of these retainers, this scoping review aimed to discuss and summarize the parameters that affect this function in CAD/CAM-manufactured telescopic crowns and to compare their retention force values with the recommended retention force. An electronic search was done in Pubmed and Google Scholar databases using different keyword combinations to find the related articles. Seventeen articles that follow the eligibility criteria for this review were selected and analyzed for detection of each of the tested parameters and their effect on retention force. The parameters tested in these articles were divided into parameters related to design, manufacturing, material type, and test condition. Regardless of the effect of these parameters, the retention force values recorded in most of the selected studies laid within or were higher than the recommended retention force (2.5–10 N), which indicated the need to design and set the combination of materials of telescopic systems according to oral biomechanics.

2021 ◽  
Vol 13 (4) ◽  
pp. e7296
Author(s):  
Magna Andréa Rabêlo Diógenes ◽  
Francisca Tauliane Lemos de Castro ◽  
Samara Kelly da Silva Cavalcante ◽  
Ana Carolina Matias Dinelly Pinto ◽  
Pedro Henrique Chaves Isaias ◽  
...  

Objetivo: Revisar acerca do efeito da fumaça do cigarro, associada ou não à escovação, na rugosidade superficial e na microdureza de uma cerâmica vítrea de dissilicato de lítio “Computer-Aided Design/Computer-Aided Manufacturing” (CAD/CAM). Métodos: Pesquisaram-se os descritores cadastrados no MeSH “lithium disilicate”, “smoking”, “CAD CAM”, “brushing”, “rough”, “hardness”, combinados entre si pelo operador booleano “AND”, na base de dados PubMed nos últimos 5 anos. Resultados: De acordo com a pesquisa, foram encontrados 625 artigos e selecionados 12 estudos in vitro. 5 estudos concluíram que as restaurações cerâmicas CAD/CAM apresentaram estabilidade de cor e de rugosidade da superfície, após escovação simulada e termociclagem.  4 estudos observaram que a escovação simulada e algumas bebidas aumentaram significativamente a rugosidade superficial da cerâmica de dissilicato de lítio. 3 estudos inferiram que a rugosidade superficial e a microdureza podem ser influenciadas pelos tratamentos de superfícies. Considerações finais: As cerâmicas de dissilicato de lítio CAD/CAM possuem propriedades satisfatórias em relação a sua resistência e estética, após exposição à fumaça do cigarro, associada ou não com a escovação.


2014 ◽  
Vol 40 (6) ◽  
pp. 758-766 ◽  
Author(s):  
Jaafar Abduo

Computer-aided design and computer-aided manufacturing (CAD/CAM) is a strongly emerging prosthesis fabrication method for implant dentistry. Currently, CAD/CAM allows the construction of implant frameworks from different materials. This review evaluates the literature pertaining to the precision fit of fixed implant frameworks fabricated by CAD/CAM. Following a comprehensive electronic search through PubMed (MEDLINE), 14 relevant articles were identified. The results indicate that the precision fit of CAD/CAM frameworks exceeded the fit of the 1-piece cast frameworks and laser-welded frameworks. A similar fit was observed for CAD/CAM frameworks and bonding of the framework body to prefabricated cylinders. The influence of CAD/CAM materials on the fit of a framework is minimal.


2018 ◽  
Vol 43 (5) ◽  
pp. 539-548 ◽  
Author(s):  
JP Andrade ◽  
D Stona ◽  
HR Bittencourt ◽  
GA Borges ◽  
LH Burnett ◽  
...  

SUMMARY The aim was to evaluate, in vitro, the influence of different computer-aided design/computer-aided manufacturing (CAD/CAM) materials (IPS e.max CAD, Vita Enamic, and Lava Ultimate) and thicknesses (0.6 mm and 1.5 mm) on the fracture resistance of occlusal veneers. Sixty human third molars were prepared to simulate advanced erosion of the occlusal surface, and the teeth were randomly divided into six experimental groups (n=10) according to the material and thickness used to build the veneers. Ten sound teeth formed the control group. The veneers were adhesively luted and submitted to mechanical cyclic loading (1 million cycles at 200-N load). The fracture resistance test was performed in a universal testing machine. The failures were classified as “reparable” and “irreparable.” According to two-way analysis of variance and the Tukey test, the interaction (material × thickness) was significant (p=0.013). The highest fracture resistance was obtained for IPS e.max CAD at a 1.5-mm thickness (4995 N) and was significantly higher compared to the other experimental groups (p<0.05). The lowest fracture resistance was obtained for Vita Enamic at 0.6 mm (2973 N), although this resistance was not significantly different from those for IPS e.max CAD at 0.6 mm (3067 N), Lava Ultimate at 0.6 mm (3384 N), Vita Enamic at 1.5 mm (3540 N), and Lava Ultimate at 1.5 mm (3584 N) (p>0.05). The experimental groups did not differ significantly from the sound teeth (3991 N) (p>0.05). The failures were predominantly repairable. The occlusal veneers of IPS e.max CAD, Vita Enamic, and Lava Ultimate, with thicknesses of 0.6 mm and 1.5 mm, obtained fracture resistances similar to those associated with sound teeth.


2019 ◽  
Vol 13 (01) ◽  
pp. 017-021
Author(s):  
Nor Faharina Abdul Hamid ◽  
Wan Zaripah Wan Bakar ◽  
Zaihan Ariffin

Abstract Objective This study was carried out to assess and compare the marginal gap of conventionally used metal onlays and new resin nanoceramic (RNC) (Lava Ultimate block) onlays. Materials and Methods This is an in vitro study using two extracted sound human mandibular molars. One tooth was prepared to receive the metal onlays and another one for the RNC onlays which were fabricated using the computer-aided design and computer-aided manufacturing (CAD/CAM) technology. Twelve metals and 12 ceramic onlays were fabricated before they were placed at their respective preparation and examined under the Leica stereomicroscope, M125C (Leica Microsystems, Wetzlar, Germany) for a marginal analysis. The gap width was measured at 10 predefined landmarks which included 3 points on the buccal and lingual surfaces each and 2 points each on the mesial and distal surfaces, respectively. Statistical Analysis Mann–Whitney post hoc test was used for statistical analysis (P ≤ 0.05). Results Overall, the RNC onlays showed significant lower marginal gap with the exception of the landmarks 5 and 6 (on distolingual) and no significant difference at landmark 7 (on midlingual). It was observed that the marginal gap were all within the clinically acceptable limit of 120 μm. Conclusions Based on the results obtained, it can be concluded that the RNC CAD/CAM onlays are a promising alternative to the metal onlays.


2021 ◽  
Vol 11 (10) ◽  
pp. 4534
Author(s):  
Gil Ben-Izhack ◽  
Asaf Shely ◽  
Omer Koton ◽  
Avi Meirowitz ◽  
Shifra Levartovsky ◽  
...  

Background: This study compared the marginal gap (MG) and absolute marginal discrepancy (AMD) of computer-aided design and computer-aided manufacturing (CAD–CAM) used in open systems (OSs) and closed systems (CSs) for producing monolithic zirconia-reinforced lithium silicate (ZLS) ceramic crowns. Methods: 60 ZLS ceramic crowns were cemented to abutment acrylic teeth; thirty crowns were designed and milled by an OS, and thirty by a CS. All crowns were sectioned for evaluating the marginal gap by scanning electronic microscopy (SEM). To compare the marginal gap between CS and OS techniques, data were analyzed using the independent-samples Mann–Whitney U Test (α = 0.05). Results: AMD was found to be significantly better for the closed system (p < 0.05). Mean AMD values for the CS were 148 µm, and for the OS it was 196 µm. MG was found to be significantly better for the OS (p < 0.05). Mean MG values for the CS were 55 µm, and for the OS they were 38 µm. Conclusions: The marginal gap in relation to AMD was significantly better for CS. However, the marginal gap in relation to MG was significantly better for OS. Both techniques showed clinically acceptable MG values (<120 µm).


2016 ◽  
Vol 10 (02) ◽  
pp. 286-291 ◽  
Author(s):  
Mehmet Selim Bilgin ◽  
Ebru Nur Baytaroğlu ◽  
Ali Erdem ◽  
Erhan Dilber

ABSTRACTThe aim of this review was to investigate usage of computer-aided design/computer-aided manufacture (CAD/CAM) such as milling and rapid prototyping (RP) technologies for removable denture fabrication. An electronic search was conducted in the PubMed/MEDLINE, ScienceDirect, Google Scholar, and Web of Science databases. Databases were searched from 1987 to 2014. The search was performed using a variety of keywords including CAD/CAM, complete/partial dentures, RP, rapid manufacturing, digitally designed, milled, computerized, and machined. The identified developments (in chronological order), techniques, advantages, and disadvantages of CAD/CAM and RP for removable denture fabrication are summarized. Using a variety of keywords and aiming to find the topic, 78 publications were initially searched. For the main topic, the abstract of these 78 articles were scanned, and 52 publications were selected for reading in detail. Full-text of these articles was gained and searched in detail. Totally, 40 articles that discussed the techniques, advantages, and disadvantages of CAD/CAM and RP for removable denture fabrication and the articles were incorporated in this review. Totally, 16 of the papers summarized in the table. Following review of all relevant publications, it can be concluded that current innovations and technological developments of CAD/CAM and RP allow the digitally planning and manufacturing of removable dentures from start to finish. As a result according to the literature review CAD/CAM techniques and supportive maxillomandibular relationship transfer devices are growing fast. In the close future, fabricating removable dentures will become medical informatics instead of needing a technical staff and procedures. However the methods have several limitations for now.


Author(s):  
A. N. Bozhko

Computer-aided design of assembly processes (Computer aided assembly planning, CAAP) of complex products is an important and urgent problem of state-of-the-art information technologies. Intensive research on CAAP has been underway since the 1980s. Meanwhile, specialized design systems were created to provide synthesis of assembly plans and product decompositions into assembly units. Such systems as ASPE, RAPID, XAP / 1, FLAPS, Archimedes, PRELEIDES, HAP, etc. can be given, as an example. These experimental developments did not get widespread use in industry, since they are based on the models of products with limited adequacy and require an expert’s active involvement in preparing initial information. The design tools for the state-of-the-art full-featured CAD/CAM systems (Siemens NX, Dassault CATIA and PTC Creo Elements / Pro), which are designed to provide CAAP, mainly take into account the geometric constraints that the design imposes on design solutions. These systems often synthesize technologically incorrect assembly sequences in which known technological heuristics are violated, for example orderliness in accuracy, consistency with the system of dimension chains, etc.An AssemBL software application package has been developed for a structured analysis of products and a synthesis of assembly plans and decompositions. The AssemBL uses a hyper-graph model of a product that correctly describes coherent and sequential assembly operations and processes. In terms of the hyper-graph model, an assembly operation is described as shrinkage of edge, an assembly plan is a sequence of shrinkages that converts a hyper-graph into the point, and a decomposition of product into assembly units is a hyper-graph partition into sub-graphs.The AssemBL solves the problem of minimizing the number of direct checks for geometric solvability when assembling complex products. This task is posed as a plus-sum two-person game of bicoloured brushing of an ordered set. In the paradigm of this model, the brushing operation is to check a certain structured fragment for solvability by collision detection methods. A rational brushing strategy minimizes the number of such checks.The package is integrated into the Siemens NX 10.0 computer-aided design system. This solution allowed us to combine specialized AssemBL tools with a developed toolkit of one of the most powerful and popular integrated CAD/CAM /CAE systems.


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