International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 04 | April-2017
p-ISSN: 2395-0072
www.irjet.net
Marginal Gap Analysis of 4-axis and 5-axis Milled Crown Copings Manmohan1, Dr. Vishal Gulati2 1PG
student, Dept. of Mechanical Engineering, GJUST, Hisar, Haryana, India. Professor, Dept. of Mechanical Engineering, GJUST, Hisar, Haryana, India.
2Associate
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Abstract – To compare the marginal fit accuracy of
comfortable. These requirements should be accomplished by any prosthesis fabrication method.
zirconia crown copings milled with 4-axis and 5-axis milling machines. Ten zirconia crown copings were milled on 4-axis milling machine and 5-axis milling machine by taking a single die. The crown copings were seated on the master die and high resolution photographs were made of the marginal area of crown copings by using GOM INSPECT V8. The marginal openings were then measured using a calibrated digital software program. The marginal gap was 4-axis milled crown copings: 0.05-0.10mm; 5-axis milled crown copings: 0.060.09mm. There was a statistically significant difference between the 4-axis milled crown copings and 5-axis milled crown copings. There was negligible difference between the crown copings manufactured by the same type of milling machine. The external marginal fit is nearly same for both type of crown copings. From comparison of marginal fit of crown copings milled on 4-axis and 5-axis milling machine, it was observed that the marginal gap for both 4-axis and 5-axis milled crown copings demonstrated within acceptable discrepancy range but the 5-axis milled crown copings resulted in smaller vertical marginal gaps than 4-axis milled crown copings. Key words: 4-Axis Milling Machines, 5-Axis Milling Machines
1.1 Crown Fabrication Using CAD/CAM A tooth that has been structurally damaged by decay or trauma sometimes needs to be crowned or “capped” so that it can look good and function properly again. A crown is a durable covering that is custom-made to fit over the entire tooth from the gum line up. Crown fabrication traditionally takes place in a dental laboratory. But these days, there is a much more convenient alternative as same-day crowns made in the dental office. CAD/CAM makes it possible to fabricate laboratorygrade crowns and other dental restorations in very short time. The process of crowning a tooth starts out the same way, whether it is a same-day crown or traditional crown that is with preparation of the tooth. This involves removing any decay that's present, and shaping the tooth with a dental drill so that it will fit perfectly inside the crown. If anyone getting a traditional crown, the next step would be to take an impression of teeth with a putty-like material, and use it to construct a model on which to create the crown. With a same-day crown, the teeth are simply given a light dusting of reflective powder and then a small scanning wand attached to a computer is used to take digital pictures inside mouth. The computer will generate a highly accurate 3D model of the teeth. With the help of the CAD/CAM software, crown will be designed in some time. The software can even be used to create a mirror-image twin of the same tooth on the other side of your mouth, for the most natural-looking result possible. Then a block of dental ceramic material is chosen in the shade that most closely matches your own teeth. The computer's digital design is transmitted to a milling machine that carves the crown from the ceramic block in about five minutes. Once the crown's fit has been verified, and any necessary aesthetic enhancements have been made to the crown's surface, the crown will be bonded to your tooth.
1. INTRODUCTION CAD/CAM has become an increasingly popular part of dentistry over the past 25 years. With the continuous development of computerized engineering technology, digitized medical treatment modalities are becoming an integral approach for prosthodontics, orthodontics, and oral and maxillofacial surgery. CAD/CAM dentistry is the field of dentistry using CAD/CAM for improving the design and creation of dental restorations, especially dental prostheses and orthodontic appliances. The advancements in CAD/CAM dentistry have restored the patient’s data into digital form for better-fitting, more durability and more natural looking than previously machined restorations. Prosthodontics is defined as the dental specialty pertaining to the diagnosis, treatment planning, rehabilitation and maintenance of the oral function, comfort, appearance, and health of patients with clinical conditions associated with missing or deficient teeth and maxillofacial tissues using a biocompatible substitute, which is most commonly prosthesis. In order for prosthesis to fulfill its function, it should be durable, aesthetic, accurate, and
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Impact Factor value: 5.181
1.2 Marginal gap in crown The most coronal position of untouched tooth structure is referred to as the Marginal Gap. This marginal gap will be the future continual line of tooth-to-restoration contact, and should be a smooth, well-defined delineation so that the restoration can be properly adapted and not allow for any openings visible to the naked eye. An acceptable distance
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