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.

Maxillary anterior all ceramic restoration using digital impression and CAD/CAM / 대한치과보철학회지

The digital impression technique has been developed for more precise restorations and convenient procedures in prosthodontic treatment compared to the conventional impression technique. Along with the utilization of CAD/CAM, the introduction of digital impression technique actualizes the digitalization of dental treatments. This case is to compare two different prostheses introducing each procedure in detail; one from CAD/CAM after taking digital impression and the other from the conventional technique. A 22-year-old female visited the clinic with the chief complaint of correction of discoloration and shape on maxillary right central incisor. Due to the trauma 8 years ago, the tooth was endodontically treated with post and resin core. The treatment was planned and the procedures were conducted under the patient's consent to treat the tooth with all ceramic crowns in two different ways for comparison. In conclusion, both prostheses presented clinically acceptable results with comparing the internal fitness of two all ceramic crowns. The prosthesis from digital impression, however, showed more errors in respect of internal fitness.

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.