The Effects of Coping Design and Firing Temperature to the Marginal Adaptation of Metal Porcelain Crowns (original) (raw)
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Effect of Coping Materials and Designs to the Marginal Adaptation of Metal Porcelain Crowns
International journal of health sciences
The Metal porcelain crowns are still widely used because of the clinically satisfactory mechanical, esthetic, marginal and internal adaptation properties and affordable, but metal collars on the marginal labial are not aesthetically acceptable because of dark shadows in the cervical region which can be overcome by marginal porcelain butt joint coping design on the marginal labial. Recent clinical studies have introduced a type of cobalt chromium coping material that is biologically more biocompatible than nickel chromium which can cause allergic reactions. In this study, Ni-Cr and Co-Cr coping materials were used with full metal collarless and modified metal collarless coping designs. The purpose of this study was to determine the effect of material and coping design on the marginal adaptation of metal porcelain crowns. This type of research is experimental laboratory. The typodontic central incisor teeth were prepared and duplicated using CAD/CAM to become zirconia and implanted in...
Influence of coping design on the cervical color of ceramic crowns
The Journal of Prosthetic Dentistry, 2013
Statement of problem. The replication of natural teeth, especially with single-tooth restorations, represents a challenge. Similar to metal ceramic crowns, different designs of zirconia substructures have been suggested to improve the esthetic results of zirconia ceramic crowns.
Acta Scientific Dental Scienecs
Objectives: To find out the colour change that occurs in the metal-ceramic and all-ceramic crowns, with full collar, 1 mm and 2 mm cutbacks employed in the substructure, using spectrophotometer. Materials and Methods: Three recently extracted maxillary premolars with no signs of damage or discoloration were mounted on an acrylic block. Color of the teeth was measured using spectrophotometer before the preparation and teeth were prepared conventionally to receive full coverage restorations. For each of the prepared tooth metal-ceramic and all ceramic (IPS Empress-lithium disilicate, Zirconia) crowns with full collar, 1 mm and 2mm cutbacks in their substructure were prepared and colour was measured using Spectrophotometer. Results: Among the materials Zirconia showed the maximum colour change and among the collars full collar showed the highest colour change. Conclusions: 1. Among the materials higher colour changes were recorded with Zirconia followed by IPS-Empress, and metal ceramic. 2. Among the three collars, higher colour changes were recorded with full collar, followed by 2mm cut back and 1 mm cut back. 3. Among all-ceramic crowns IPS Empress crowns showed less change in colour than the Zirconia. 4. Amongst the three types of crowns fabricated, zirconia exhibited higher change in colour than IPS Empress and metal-ceramic. 5.Presence of a full collar in the metal-ceramic crowns, IPS Empress and zirconia crowns can cause colour change. To obtain colour match it is desirable to employ cutback preferably of 2 mm.
Influence of framework design on the cervical color of metal ceramic crowns
The Journal of Prosthetic Dentistry, 2011
If metal ceramic is selected as the restorative material for a crown in the esthetic zone, a vertical cutback of approximately 1 mm is recommended on the facial metal framework/ porcelain facial margin to achieve an adequate esthetic result. If a conventional metal framework design is selected, deep subgingival margins might reduce the color impairment. Statement of problem. The replication of natural teeth, especially for single tooth restorations in patients with high esthetic needs, represents a challenge. Purpose. The purpose of the study was to analyze the color of the cervical portion of single metal ceramic crowns fabricated with different metal framework designs. Material and methods. The color, as measured on the CIELAB color scale, of 3 different groups of restorations (n=10) fabricated with a high noble metal alloy (V-Deltaloy) and feldspathic porcelain (Noritake Super Porcelain) was analyzed with a colorimeter. Conventional metal ceramic crowns with metal facial margins were compared to metal ceramic crowns with porcelain facial margins and a horizontal reduction of the metal framework (1.0 mm reduction) or an additional vertical reduction (1.0 mm reduction). In all specimens, the finish line was positioned at a subgingival or equigingival level. The 6 groups obtained by the combination of the levels of the 2 factors (framework extension and finish line location) were examined with an ANOVA Fisher's F-test and a post hoc Tukey's HSD test (α=.05). Results. The mean color difference for all the groups was clinically acceptable (∆Ε<3.7). Conventional metal ceramic crowns showed higher differences in relation to finish line location (∆Ε=2.34), while a vertical reduction of the framework was related to lower values (∆Ε=0.96). Mean Lab* values were reported for all the groups of crowns. Statistically significant differences were present for L*, a*, and b* values when related to framework extension. Considering each value in relation to the interaction between framework extension and finish line location factors, significant differences were present only for L* and a* values. Conclusions. No significant differences in base shade were present among the investigated crowns. Nevertheless metal ceramic crowns with vertical cutback and porcelain facial margins presented more consistent results that tended to be closer to those of natural teeth.
Statement of Problem.Although metal ceramic and zirconium dioxide restorations are widely used, there is a lack of information about how the fit is affected by fabrication procedures. The adequacy of the fit of all-ceramic restorations hasbeen questioned. Purpose. This study examined the effect of porcelain and glaze firing cycles on the fit of metal ceramic and zirconium dioxidecrowns. Material and methods.Fifteen standardized metal ceramic copings, zirconia copings and further crowns were fabricated on a metal die.A device was used to apply a uniform load on specimens during measurement and to reposition thespecimens on the measurement device after each manufacturing process. The specimens were not cemented andwere measured on the metal die using a stereomicroscope. Measurements were recorded at 18 points selectedalong horizontal and vertical planes. The crown systems were compared by use of the Student t test and 1-wayanalysis of variance (ANOVA). Analysis of Variance (ANOVA) and independent t-test were used for intra-and inter-group comparisons of marginal gap of metal copings, zirconia copings, porcelain fused to metal crowns and zirconia crowns. Results.In this study mean marginal openings for conventionally fabricated metal copings was 18µm, for CAD/CAM fabricated zirconia copings was 10µm, for metal ceramic crowns was 20µm and for zirconia crowns it was 14µm respectively.The meanwise comparison of marginal gap of metal copings, zirconia copings and metal ceramic crowns, zirconia dioxide crowns were measured on all the surfaces. The mean difference obtained wasmaximum on mesial surface and minimum on the labial surface which was statistically significant as p value was< 0.05. No statistical difference was observed in zirconia copings and zirconia crowns. Conclusion.Within the limitations of this study, it was concluded thatdistortion does occur in fixed prostheses during the porcelain firing cycle. Zirconia system showed significantly less distortion as compared to metal ceramic system. After veneering of zirconia copings marginal discrepancy was increased. Higher mean marginal gap was recorded in metal (Ni-Cr) copings and porcelain fused to metal crowns compared to zirconia copings and crowns. The difference in mean marginal gap between them was found to be statistically significant
2017
PURPOSE: To compare the marginal fit of all metal, porcelain fused to metal and all ceramic crowns fabricated using different materials and techniques commercially available. MATERIALS AND METHODS: 80 freshly extracted human mandibular first premolars were divided into 8 groups of 10 each which received Nickel-Chromium (Ni-Cr) all metal (AM) crowns, Cobalt-Chromium (Co-Cr) AM crowns, Ni-Cr three-quarter crowns, Co-Cr three quarter crowns, porcelain fused to metal (PFM) crowns with Ni-Cr copings, PFM crowns with Co-Cr copings, pressed all ceramic (AC) crowns and CAD/CAM fabricated AC crowns respectively. Crowns were cemented and specimen were sectioned buccolingually. The marginal gap was evaluated under a stereomicroscope. Lesser marginal gap indicated a better marginal fit. RESULTS: The mean marginal gap was maximum for Group 8 (222.3 μm) and least for Group 1 (85.5 μm). The mean marginal gaps for ‘all metal crowns’ and ‘metal ceramic crowns’ showed significantly lesser marginal ga...
A two-year clinical study of metal-ceramic and metal-polymer crowns
Prague medical report
The purpose of this study was to compare full metal crowns with two different types of veneering material -ceramics and polymer after a two-year period in a function. The aim was to evaluate the changes of occlusal relief, marginal adaptation, break of material, changes of shape and color and gingival status. One hundred and two crowns were examined in 34 patients immediately after cementation, and they were reviewed within two years of crown placement. These fixed restorations were checked according two modified US Public Health Service System criteria. After two years the crowns were found clinically intact in 94 % for metal-ceramics versus 98 % for metal-polymer. No crown was lost. There were found significant differences in positions of a crown margin between both materials and marginal adaptation between initial (baseline) and follow-up results. Gingival health at baseline was related in optimal in 67 % versus 77 %, after two years in 43 % versus 71 %. Slight mismatch in color occurred in 0 versus 60 % crowns, obvious mismatch was apparent in 0 versus 21 % crowns after two years. Within the limitations of this study, it was found that the examined metal crowns with two different veneerings are very stable fixed restorations, mechanical resistance and integrity of polymer material was surprisingly good but its color stability presented mismatch after two-years period. Ceramic veneering was excellent in color match but there were three visible cracks of the ceramic layer.
Revista de Chimie
Copings accuracy is an important factor for long-term clinical success of ceramic fused to metal dental restorations. The purpose of the study was to investigate marginal and internal fit of metal-ceramic crowns during processing, using conventional and digitized technologies. Metal copings were produced by Digital light Processing (DLP), invested and casted. Ceramic veneers were overpressed. Internal and marginal fit was measured using silicon replica technique for patterns, casted frameworks and final ceramic fused to metal crowns. Best adaptation was found in resin-pattern group, with small increasing of gap after casting and after ceramic pressing.