Qualitative study of repaired metal ceramic crowns EMANUELA PETRESCU, MEDA LAVINIA NEGRUTIU, COSMIN SINESCU, MARIA DANIELA POP, ROXANA ROMINU, FLORIN TOPALA, MIHAI ROMINU, ADRIAN GH. PODOLEANU. Department of Dental Materials and Dental Technologies University of Medicine and Pharmacy Victor Babes B-dul Revolutiei, nr. 9, Timisoara ROMANIA emanuelapetrescu@yahoo.com Abstract: - The purpose of this study is to investigate the reparation of metal ceramic crowns with ceramic mass. 30 metal ceramic crowns which restore the upper first central incisor (2.1) were divided in three groups. Each group was repaired with a different ceramic material. Group 1- In Line (Ivoclar Vivadent) ceramic, the second group was repaired with D.Sign (Ivoclar Vivadent) and for the last group was used VMK.Master (Vita). All the repaired crowns were investigated through imagistic non-invasive methods. The metallic infrastructure of the samples was made from Ni-Cr alloy and the porcelain mass was Kiss (D.Sign). Defects were made on the buccal surface of each crown. The ceramic mass and the opaque were removed and the metallic infrastructure was exposed. Size defects has 3x3mm and it is situated on incise and 1/3 medium buccal surface. The defect was made with a green grinding instrument under air-water cooling. All the samples were conditioned and repaired with ceramic mass. The reparations were investigated with two noninvasive imagistic methods Rx and Optical Coherence Tomography Time Domain in order to detect de reparation’s defects. The investigation methods may spot the presence or absence defects localized at the interface between the two materials and those localized in the ceramic mass. Key-Words: - metal ceramic crown, defect, reparation, ceramic mass, non-invasive investigation, imagistic investigation 1 Introduction We can consider that metal ceramic crowns have a long history in dentistry and have proven during 40 years their qualities and represent the result of the progresses made in dentistry. Metal ceramic prosthesis were tested and studied and despite of all these tests, proved their superior qualities and were considered the best option for restoring partial edematous arches. Metal-ceramic crowns respect three important principles: esthetics, functional- oclusal and mechanical resistance. Metal-ceramic crowns have a metallic infrastructure which can be made through different techniques: pouring, galvanization and sintering and grinding- CAD/CAM. Despite of the new techniques developed for making the metallic infrastructure, the pouring method is best choice. Metallic infrastructure may be made through different techniques from noble, non noble alloys and titan through. The metallic component cover the dental abutment, protect the cervical limit of the abutment, delimitate the physiognomic component, assure the morphology of occlusal surface and incises margins, sustain the ceramic mass, assure the infrastructure’s stability and respect the physiognomic requests. The longevity of metal-ceramic systems, specifically the integrity of the veneering porcelain layer depends by the framework’s design. For increasing the long term prognosis of the porcelain veneer two practitioners can apply one of the two principles: (1) the porcelain is veneered with the minimum thickness compatible with good esthetics, and (2) the porcelain is supported by the coping so that the tensile or shear fractures can be minimized. An excessively thick porcelain layer may be more liable to shear and tensile force that may generate fractures under occlusal loading. The technology of performing metal-ceramic crowns or fixed partial dentures is involving many stages which can lead to errors and failure of the restoration. Such errors are represented by the lack of adaptation of metallic infrastructure, porosities and extra material on the surface of metallic infrastructure, absence of metallic material in the cervical area, precarious adaptation of metallic infrastructure, porosities in ceramic mass, fissure and fractures on the surface or into the deep layers of ceramic mass. Detaching of Recent Researches in Computational Techniques, Non-Linear Systems and Control ISBN: 978-1-61804-011-4 295