Effect of additional firing process after sintering of monolithic zirconia crown on marginal and internal fitness / 대한치과보철학회지

PURPOSE: To evaluate an effect of additional firing process after sintering of monolithic zirconia crown on marginal and internal fit through three-dimensional analysis. MATERIALS AND METHODS: Ten monolithic zirconia crowns were fabricated using titanium abutment model. Monolithic zirconia crowns were designed, milled, and sintered as a control group, and additional firing with coloring was performed as a test group. Three dimensional analysis were performed by using triple-scan protocol, and cross-section analysis on mesio-distal and disto-lingual section was evaluated to measure marginal and internal fitness. Then, three-dimensional surface difference on between two groups was evaluated (α=.05). RESULTS: There was statistically significant difference between the control group (32.0 ± 24.3 µm) and the test group (17.0 ± 10.8 µm) in the mesial axial wall (P < .02) and the control group (60.2 ± 24.3 µm) and the test group (71.8 ± 21.5 µm) in the distal axial wall (P < .01). There was no statistically significant difference at the remaining point. CONCLUSION: There was no statistical significance on the deviation of inner surface of crown according to firing number, and the results of both group were considered clinically acceptable.

Marginal and internal fit of all ceramic crown using the replica technique and the triple-scan protocol / 대한치과보철학회지

PURPOSE: This study was conducted to compare the marginal and internal fit of all ceramic crown using the replica technique and the triple-scan protocol. MATERIALS AND METHODS: Twenty zirconia ceramic crowns were fabricated using titanium abutment model. All crowns were divided into two groups of 10 each, depending on the replica technique and the triple-scan protocol. The internal and marginal fit of 10 zirconia ceramic crowns were measured at 17 points for each specimen using the replica technique. The other 10 ceramic crowns were measured using the triple-scan protocol. Statistical analysis was performed by t-test (α= .05). RESULTS: The mean and standard deviation of marginal and internal fit were significantly different between the replica technique (49.86 ± 29.69 µm) and triple-scan protocol (75.35 ± 64.73 µm, P.343). CONCLUSION: There was a statistically significant difference in the marginal fit measured by the two methods. However, there was no statistically significant difference in the internal fit between the two methods.

Marginal and internal fitness of three-unit zirconia cores fabricated using several CAD/CAM systems / 대한치과보철학회지

PURPOSE: This study was aimed to compare the margin and internal fitness of 3-unit zirconia bridge cores fabricated by several CAD/CAM systems using replica technique. MATERIALS AND METHODS: Three unit-bridge models in which upper canine and upper second premolar were used as abutments and upper first premolar was missed, were fabricated. Fourty models were classified into 4 groups (Cerasys(R) (Group C), Dentaim(R) (Group D), KaVo Everest(R) (Group K), Lava(TM)(Group L)), and zirconia cores were fabricated by each company. Sixteen points were measured on each abutment by replica technique. Statistical analysis was accomplished with two way ANOVA and Dunnett T3 (alpha=.05). RESULTS: In most systems, there was a larger gap on inter margin than outer margin. In the Group K, overall fitness was excellent, but the incisal gap was very large. In the Group C, marginal gap was significantly larger than Group K, but overall internal gap was uniform (P<.05). The axial gap was under 100 microm in all system. The difference between internal and external gap was small on Group L and C. However, internal gap was significantly larger than external gap in Group D (P<.05). The fitness of canine was better than second premolar among abutments (P<.05). CONCLUSION: The marginal and internal gap was within the clinically allowed range in all of the three systems. There was a larger gap on second premolar than canine on internal and marginal surface. In most systems, there was a larger gap on occlusal surface than axial surface.

Evaluation using Replica Technique on the marginal and internal fitness of zirconia cores by several CAD/CAM systems / 대한치과보철학회지

PURPOSE: This study was aimed to compare the margin and internal fitness of single anterior all-ceramic crown zirconia core made by three deferent CAD/CAM systems. MATERIAL AND METHODS: Five single zirconia cores were manufactured by three deferent CAD/CAM systems(Cerasys(R)system, KaVo Everest(R)system, Lava(TM) system). The manufactured zirconia cores were duplicated through the use of replica technique, and a replicated sample was sectioned in the center of bucolingual and mesiodistal direction to measure the marginal and internal gap. Measurement was carried out by using measuring microscope (AXIO(R)) and I-Solution(R) and analysed through the use of ANOVA. RESULTS: As for the mean marginal fitness of the zirconia core, it was 84.74 +/- 27.57 micrometer, in Cerasys(R), 80.23 +/- 21.07 micrometer in KaVo Everest(R) and 96.37 +/- 11.45 micrometer in Lava(TM), and as for the mean internal gap, it was 94.11 +/- 30.07 micrometer in Cerasys(R), 92.31 +/- 25.18 micrometer in KaVo Everest(R), and 94.99 +/- 18.74 micrometer in Lava(TM). There was no significant statistically deference among the total average gap of three systems. The internal gap in KaVo Everest(R) seemed to be smaller than Lava(TM) (P < .05). The internal gap in the incisal area was larger in all of the three systems. CONCLUSION: There was no difference in marginal fitness in Cerasys(R), KaVo Everest(R) and Lava(TM). As for the internal fitness, it was smaller in KaVo Everest(R) system than Lava(TM)system. In all of the three systems, there was a larger gap in incisal area. The marginal and internal gap was within the clinically allowed range in all of the three systems.

Fracture load and marginal fitness of zirconia ceramic coping by design and coloration / 대한치과보철학회지

PURPOSE: The purpose of this study was to compare the marginal fitness and fracture load of the zirconia copings according to the design with different thickness and coloration. MATERIAL AND METHODS: The evaluation was based on 80 zirconia copings. Zirconia copings were fabricated in design with different thicknesses using CAD/CAM system (Everset, KAVO dental GmbH, Biberach, Germany). The designs of copings were divided into four groups. The first group consisted of copings with uniform thickness of 0.3 mm. The thickness in the second group was 0.3 mm on the buccal surface and 0.6 mm on the lingual surface. The third group consisted of coping with uniform thickness of 0.6 mm. The thickness in the fourth group was 0.6 mm on the buccal surface and 1mm on the lingual surface. Each group consisted of 10 colored and 10 uncolored copings. Half of the copings (40) processed with a milling system according to the specific design were sent to be given a color (A3) through saturation in special dye by a manufacturing company. Just after sintering, the marginal discrepancies of copings were measured on the buccal, lingual, mesial and distal surfaces of metal die, under a Video Microscope System (sv-35, Sometech, Seoul, Korea) at a magnification of x100. It was remeasured after the adjusting of the inner surface. Next, all copings were luted to the metal dies using reinforced cement {GC FujiCEM (GC Corp. Tokyo, Japan)} and mounted on the testing jig in a Universal Testing Machine (Instron 4467, Norwood, MA, USA). The results were analyzed statistically using the one-way ANOVA test. RESULTS: The obtained results were as follow: 1. The measured value of marginal discrepancy right after sintering was the greatest in the contraction of the buccal area in all groups, except for group I2. 2. There was no significant difference of marginal fitness among the groups in the colored zirconia group (P.05), with no significance. CONCLUSION: There was difference in the marginal fitness according to the design and coloration of zirconia copings right after sintering, but it was decided that the copings may well be used clinically if the inner surface are adjusted. The copings should be thick enough for the reinforcement of fracture strength. But considering the esthetics of the visible surfaces (labial and buccal surface), the thickness of copings may be a little thin, without giving any significant effect on the fracture strength. This type of design may be considered when giving priority to preservation of tooth or esthetics.

Marginal fit related to margin types of glass infiltrated alumina core fabricated from aqueous-based alumina tape / 대한치과보철학회지

STATEMETN OF PROBLEM: In-Ceram system is one of the all-ceramic crowns that can be used in anterior 3 unit fixed partial dentures and posterior single crowns. The alumina core used in In-Ceram system is manufactured using slip-casting technique. The slip-casting technique is difficult and technique sensitive. To improve this problem, tape-casting method was introduced into dentistry. There were no studies to examine the effect of margin design on the margin fit-ness of all-ceramic crowns fabricated from alumina tape. PURPOSE: The purpose of this study was to compare the marginal fitness of glass infiltrated alu-mina core fabricated from aqueous-based alumina tape according to different margin types (90 .,110 ., 135 .shoulder margin). MATERIAL AND METHOD: Three upper central resin incisors were prepared with 90 ., 110 .and 135 .shoulder margins for all-ceramic crowns, respectively. The resin teeth were duplicated and master die and special plaster die were made as usual. After alumina cores were fabri-cated from aqueous-based alumina tape, cores were cemented to each 15 epoxy dies replicated from three resin teeth with resin cement. These cemented cores were embedded in epoxy resin. Specimens were cut mesiodistally and buccolingually. Marginal gap and discrepancy were measured under microscope. RESULTS: The marginal gap and discrepancy of 90.marginal angle was 75.1 mu m, 86.6 mu m, 110 .marginal angle was 41.5 mu m, 50.7 mu m and 135 .marginal angle was 51.7 mu m, 54.2 mu m, respectively. The smallest value was seen in 110 (angle, which was statistically significant com-pared to that of 90 .angle (p<0.05). CONCLUSION: Marginal fitness of alumina cores made of alumina tape with 110 .shoulder mar-gin was best and others were clinically acceptable.

MARGINAL FITNESS AND MARGINAL LEAKAGE OF FIBER-REINFORCED COMPOSITE CROWNS DEPENDING UPON LUTING CEMENTS / 대한치과보철학회지

As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation, conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiberreinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements.(Bistite II., Super-bond., Variolink II.), Zinc phosphate and Glass- Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of 5degrees C and 55degrees C in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II(46.78micrometer), Variolink II(56.25micrometer), Super-Bond(56.78 micrometer), Glass-Ionomer(99.21micrometer), Zinc Phosphate(109.49micrometer) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate. 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.