Purpose: To comparatively evaluate the amount of wear of natural enamel against a glazed full coverage monolithic zirconia crown and a polished monolithic zirconia crown at 6 and 12 months. Materials and Methods: Thirty subjects within the age range of 18 to 35 years participated in this study. The subjects received a total of 60 single crowns, which were divided into two groups: (1) 30 glazed monolithic zirconia crowns opposed by natural enamel (group A); and (2) 30 polished monolithic zirconia crowns opposed by natural enamel (group B). Each subject received a crown from both groups, placed bilaterally in endodontically treated maxillary or mandibular first molars. An impression was made of the opposing arch at 24 hours, 6 months, and 12 months. The resulting casts were scanned with a 3D optical scanner. The recall scans were superimposed and compared to baseline scans using 3D AutoCAD software. A control group was included to compare the wear values to natural enamel against natural enamel. Results: No significant difference (P = .855) was found in enamel wear between groups A (42.80 μm) and B (42.50 μm) after 6 months of use. However, a significant difference (P < .05) in enamel wear was found between group A (81.87 μm) and group B (71.43 μm) after 12 months of use. Conclusion: Glazed monolithic zirconia crowns cause more wear to the opposing enamel than polished monolithic zirconia crowns after 12 months of clinical use.
Prosthodontists usually stick to the dictum by MM Devan, “preservation of what remains than meticulous replacement of what has been lost.1” “Microtia” is a term used to describe congenital anomaly of the external ear. It is a combination of the words “micro” and “otia” each of the term denoting small and ear respectively. It includes a range of deformities which may consist of presence of a rudimentary ear, a grossly normal or smaller ear or complete absence of the entire external ear. These deformities usually account for 3 in every ten thousand births, with less than 10 % of all the cases showing bilaterally missing ears.2-4 Facial deformities are common for the microtia patient as the auricle develops from tissues of the branchial arches. Figure 1 describes the patient having congenitally missing unilateral ear. Maxillofacial prosthodontics deals with prosthetic rehabilitation of disfigured or missing parts of head and neck. Prosthetic replacement of the exterior part (Epithesis) can be related to as old as civilization. References to it are available in Indian, Greek, Roman, Egyptian Civilizations.5 Ambroise Pare is credited with making various contributions to the materials and techniques in facial prosthetics. Fabrication of an extra-oral prosthesis is probably more of an art than science. Throughout the recorded history, humans have attempted to restore missing parts of the body by using various artificial materials. MPF materials have evolved since centuries right from metals, ivory, porcelain, waxes, natural rubber, gelatin, and latex to modern day materials such as methacrylate or acrylic resins, polyurethane elastomers, and silicone elastomers each having their own set of advantages and disadvantages. But silicone is most commonly used because of its assorted benefits over other MFP materials. This case report describes an auricular prosthesis for the patient with congenital ear deformity using an acrylic template for colour depiction and room temperature volcanizing (RTV) silicone.6
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