PURPOSE: The purpose of the present study was to compare the accuracy of four different metal copings fabricated by CAD/CAM technology and to evaluate clinical effectiveness. MATERIALS AND METHODS: Composite resin tooth of the maxillary central incisor was prepared for a metal ceramic crown and duplicated metal die was fabricated. Then scan the metal die for 12 times to obtain STL files using a confocal microscopy type oral scanner. Metal copings with a thickness of 0.5 mm and a cement space of 50 µm were designed on a CAD program. The Co-Cr metal copings were fabricated by the following four methods: Wax pattern milling & Casting (WM), Resin pattern 3D Printing & casting (RP), Milling & Sintering (MS), Selective laser melting (SLM). Silicone replica technique was used to measure marginal and internal discrepancies. The data was statistically analyzed with One-way analysis of variance and appropriate post hoc test (Scheffe test) (α=.05). RESULTS: Mean marginal discrepancy was significantly smaller in the Group WM (27.66 ± 9.85 µm) and Group MS (28.88 ± 10.13 µm) than in the Group RP (38.09 ± 11.14 µm). Mean cervical discrepancy was significantly smaller in the Group MS than in the Group RP. Mean axial discrepancy was significantly smaller in the Group WM and Group MS then in the Group RP and Group SLM. Mean incisal discrepancies was significantly smaller in the Group RP than in all other groups. CONCLUSION: The marginal and axial discrepancies of the Co-Cr coping fabricated by the Wax pattern milling and Milling/Sintering method were better than those of the other groups. The marginal, cervical and axial fit of Co-Cr copings in all groups are within a clinically acceptable range.
Ceramics ; Crowns ; Dental Marginal Adaptation ; Freezing ; Incisor ; Methods ; Microscopy, Confocal ; Printing, Three-Dimensional ; Replica Techniques ; Silicon ; Silicones ; Tooth ; Treatment Outcome

PURPOSE: The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality. MATERIALS AND METHODS: 58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient. RESULTS: Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17–73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, P<.01) at 24 months. At the last observation, over 90% of all crowns showed excellent ratings (CDA-rating Alfa) for color, marginal fit, and caries. CONCLUSION: Heat pressed lithium disilicate crowns showed an excellent performance. Besides a careful luting, dentists should be aware of patients' biological prerequisites (grade of caries, oral hygiene) to reach full success with these crowns.
Crowns* ; Dataset ; Dental Bonding ; Dental Marginal Adaptation ; Dental Porcelain ; Dental Pulp Cavity ; Dental Restoration Failure ; Dentists ; Female ; Follow-Up Studies ; Hot Temperature ; Humans ; Jaw ; Lithium* ; Prospective Studies ; Resin Cements ; Survival Analysis ; Survival Rate ; Tooth ; Tooth Fractures

OBJECTIVETo evaluate the adaptation of different lithium disilicate glass-ceramic crown and whether different fabrication processes affect the adaptation of crowns.

METHODSThirty epoxy dies crowns were divided into 3 groups. They were cemented to domestic lithium disilicate glass-ceramic crowns in Group A, to IPS e.max CAD crowns in Group B and to IPS e.max Press crowns in Group C respectively. All crowns were cut by cutting machine. A confocal laser scanning microscope was used to measure the gap between crown tissue surface and die.

RESULTSThere were significant differences in the three groups of measurement points(P<0.05). Within the groups, specimens in group A showed in the lowest marginal fit([46.8±9.1] μm). Those in group B showed the lowest shoulder suitability([59.3±7.9] μm), axial plane([50.5±3.6] μm) and occlusal surface([87.6±11.6 μm]. Those in group C demonstrated the lowest axial plane angle[(84.4±10.1) μm]. In addition to the axial plane angle, the CAD/CAM system exhibited good accuracy of fit.

CONCLUSIONSThe three groups of lithium disilicate glass-ceramic crowns appeared to have clinically acceptable fit.

Ceramics ; Computer-Aided Design ; Crowns ; Dental Marginal Adaptation ; Dental Porcelain ; Dental Prosthesis Design ; methods ; Humans ; Microscopy, Confocal ; Surface Properties

OBJECTIVETo investigate the effect of three different impression methods on the marginal fit of all-ceramic crowns. The three methods include scanning silicone rubber impression, cast models, and direct optical impression.

METHODSThe polymethyl methacrylate (PMMA) material of a mandibular first molar in standard model was prepared with 16 models duplicated. The all-ceramic crowns were prepared using three different impression methods. Accurate impressions were made using silicone rubber, and the cast models were obtained. The PMMA models, silicone rubber impressions, and cast models were scanned, and digital models of three groups were obtained to produce 48 zirconia all-ceramic crowns with computer aided design/computer aided manufacture. The marginal fit of these groups was measured by silicone rubber gap impression. Statistical analysis was performed with SPSS 17.0 software.

RESULTSThe marginal fit of direct optical impression groups, silicone rubber impression groups, cast model groups was (69.18±9.47), (81.04±10.88), (84.42±9.96) µm. A significant difference was observed in the marginal fit of the direct optical impression groups and the other groups (P<0.05). No statistically significant difference was observed in the marginal fit of the silicone rubber impression groups and the cast model groups (P>0.05).

CONCLUSIONAll marginal measurement sites are clinically acceptable by the three different impression scanning methods. The silicone rubber impression scanning method can be used for all-ceramic restorations.

Computer-Aided Design ; Crowns ; Dental Marginal Adaptation ; Dental Porcelain ; Dental Prosthesis Design ; Zirconium

OBJECTIVETo investigate the effects of different tooth preparations on three-dimensional adaption of computer aided design and computer aided manufacturing (CAD/CAM) crowns based on the reverse engineering.

METHODSThe tooth preparation model of the left maxillary first molar was scanned to build five different tooth preparations using the NX Imageware 13.2 software. The resin cores (n=8) were designed with the exocad software. The scanning data of the inner surface of each resin core were used to analyze the three-dimensional adaption with the Geomagic Qualify 12 software.

RESULTSAccording to the color-coded deviation images, the deviation of the heavy chamfer shoulder was the smallest and the most uniform, whereas the other groups with sharp lines showed large deviation. After statistical analysis, the total deviation of the heavy chamfer shoulder, 135° shoulder, feather shoulder, 90° shoulder with lipped margins, and sharp marginal ridges preparation were (16.88±2.83), (26.88±3.61), (53.56±4.30), (51.38±4.46), and (47.19±4.62) μm. A statistical significance was observed between the heavy chamfer and 135° shoulders (P<0.05). The other groups fitted poorly, without statistical significance between each group (P>0.05).

CONCLUSIONThree-dimensional analysis using a computer is a preferable method to study the three-dimensional adaption of crowns. The heavy chamfer shoulder and round line preparation are clinically recommended. However, feather shoulder, 90° shoulder with lipped margins, and sharp marginal ridge preparation should be avoided.

Composite Resins ; Computer-Aided Design ; Crowns ; Dental Marginal Adaptation ; Dental Prosthesis Design ; Humans ; Molar ; Tooth Preparation ; Tooth Preparation, Prosthodontic

PURPOSE: The purpose of this study is to see what impact the heat and press-on-metal technique has on the marginal fit of metal ceramic crown. MATERIALS AND METHODS: Prior to the experiment, 4 metal master models were prepared. Each model has margin of chamfer, margin of heavy chamfer, margin of shoulder with bevel and margin of shoulder (collarless). Additionally, 10 crowns were made for each margin, total of 40 crowns. Marginal discrepancy between the master model and crown was observed at x100 microscopic magnification in two states; in coping state and upon completion of making metal ceramic crown. Data analysis was performed using paired t-test along with one-way ANOVA and Duncan multiple comparison test. RESULTS: After analyzing mean and standard deviation of marginal discrepancy, it was confirmed that marginal discrepancies were within the clinical permitted range for all states; in coping state and upon completion of making metal ceramic crown. For the chamfer group, a significant increase in marginal discrepancy upon completion of making metal ceramic crown was observed compared to the heavy chamfer group. Also, a marginal discrepancy of porcelain margin in shoulder group was significantly less than the marginal discrepancy of metal margin in chamfer and shoulder group. CONCLUSION: From the test result, one can conclude that marginal fit of metal ceramic crown built with heat and press-on-metal technique is not significantly different from marginal fit of metal ceramic crown built with traditional technique. And along with efficiency of this system, heat and press-on-metal technique is considered in clinic.
Ceramics ; Crowns* ; Dental Marginal Adaptation ; Dental Porcelain ; Hot Temperature* ; Shoulder ; Statistics as Topic

The present investigation assessed the effect of acid etching on marginal adaptation of white- and gray-colored mineral trioxide aggregate (MTA) to apical dentin using microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Sixty-four extracted single-rooted human maxillary teeth were used. Following root-end resection and apical preparation, the teeth were equally divided into four groups according to the following root end filling materials: (i) white-colored MTA (WMTA), (ii) etched WMTA (EWMTA), (iii) gray-colored MTA (GMTA) and (iv) etched GMTA (EGMTA). After 48 h, the interface between root-end filling materials and the dentinal walls was assessed using micro-CT and SEM. Data were statistically analyzed using the Kruskal-Wallis and Dunn tests. Micro-CT analysis revealed gap volumes between the apical cavity dentin walls and EGMTA, GMTA, EWMTA and WMTA of (0.007 1±0.004) mm(3), (0.053±0.002) mm(3), (0.003 6±0.001) mm(3) and (0.005 9±0.002) mm(3) respectively. SEM analysis revealed gap sizes for EGMTA, WMTA, EWMTA and GMTA to be (492.3±13.8) µm, (594.5±17.12) µm, (543.1±15.33) µm and (910.7±26.2) µm respectively. A significant difference in gap size between root end preparations filled with GMTA and EGMTA was found (P<0.05). No significance difference in gap size between WMTA and EWMTA were found in either SEM or micro-CT analysis. In conclusion, pre-etching of apical dentin can provide a better seal for GMTA but not for WMTA.
Acid Etching, Dental ; methods ; Aluminum Compounds ; chemistry ; Apicoectomy ; methods ; Calcium Compounds ; chemistry ; Dental Bonding ; Dental Marginal Adaptation ; Dental Pulp Cavity ; ultrastructure ; Dentin ; ultrastructure ; Drug Combinations ; Humans ; Materials Testing ; Microscopy, Electron, Scanning ; Oxides ; chemistry ; Retrograde Obturation ; methods ; Root Canal Filling Materials ; chemistry ; Root Canal Preparation ; instrumentation ; methods ; Silicates ; chemistry ; Surface Properties ; Time Factors ; Tooth Apex ; ultrastructure ; X-Ray Microtomography

OBJECTIVETo investigate the marginal adaptation of crowns fabricated by selective laser melting (SLM) and wax-lost-casting method, so as to provide an experimental basis for clinic.

METHODSCo-Cr alloy full crown were fabricated by SLM and wax-lost-casting for 24 samples in each group. All crowns were cemented with zinc phosphate cement and cut along longitudinal axis by line cutting machine. The gap between crown tissue surface and die was measured by 6-point measuring method with scanning electron microscope (SEM). The marginal adaptation of crowns fabricated by SLM and wax-lost-casting were compared statistically.

RESULTSThe gap between SLM crowns were (36.51 ± 2.94), (49.36 ± 3.31), (56.48 ± 3.35), (42.20 ± 3.60) µm, and wax-lost-casting crowns were (68.86 ± 5.41), (58.86 ± 6.10), (70.62 ± 5.79), (69.90 ± 6.00) µm. There were significant difference between two groups (P < 0.05).

CONCLUSIONSCo-Cr alloy full crown fabricated by wax-lost-casting method and SLM method provide acceptable marginal adaptation in clinic, and the marginal adaptation of SLM is better than that of wax-lost-casting method.

Chromium Alloys ; Computer-Aided Design ; Crowns ; Dental Casting Technique ; Dental Marginal Adaptation ; Dental Prosthesis Design ; Freezing ; Lasers

OBJECTIVETo evaluate the effect of gap size between tooth and restorative materials on microbiolism based caries in vitro.

METHODSTooth blocks made of human molars without caries and the same size composite resin blocks were selected and prepared. Tooth-resin matrix was mounted on resin base with a gap size of 0, 25, 50, 100, 190, 250 µm and a control group was dealed with adhesive system. Six experimental groups and one control group were included, with 8 samples in one group and a total of 56 samples. The samples were cultured by a 14-day sequential batch culture technique. The development of outer surface lesion and wall lesion was assessed with confocal laser scanning microscope (CLSM) by measuring the maximum lesion depth, fluorescence areas and average fluorescence value. The data were collected and statistically analyzed. The deposits of the tooth-restoration interface and the development of the carious lesion were observed by scanning electron microscope (SEM).

RESULTSMost groups showed outer surface lesion and wall surface lesions observed by CLSM and SEM except 2 samples in control group. There was no significant difference on the outer surface lesion (P > 0.05). The maximum lesion depth [(1145.37 ± 198.98), (1190.12 ± 290.80) µm respectively], the maximum lesion length, fluorescence areas and average fluorescence value of 190 and 250 µm groups' wall lesions were significantly higher than the 0, 25, 50 and 100 µm groups [the maximum lesion depth was (205.25 ± 122.61), (303.87 ± 118.80), (437.75 ± 154.88), (602.87 ± 269.13) µm respectively], P < 0.01. With the increase of the gap size, the demineralization developed more seriously. While the maximum lesion depth, the maximum lesion length and fluorescence areas of 0, 25, 50 µm groups' wall lesions were of no significant difference.

CONCLUSIONSThere was close relationship between gap size and wall lesion when the gap was above 100 µm at tooth-composite resin interface. The existence of gap was the main influencing factor on the development of microbiolism based caries lesion.

Acrylic Resins ; Adolescent ; Adult ; Composite Resins ; Dental Bonding ; Dental Caries ; etiology ; microbiology ; pathology ; Dental Enamel ; pathology ; Dental Marginal Adaptation ; Dental Restoration, Permanent ; Humans ; Microscopy, Confocal ; Microscopy, Electron, Scanning ; Molar ; pathology ; Polyurethanes ; Streptococcus mutans ; pathogenicity ; Young Adult

PURPOSE: The anterior region is a challenge for most clinicians to achieve optimal esthetics with dental implants. The provisional crown is a key factor in the success of obtaining pink esthetics around restorations with single implants, by soft tissue and inter-proximal papilla shaping. Provisional abutments bring additional costs and make the treatment more expensive. Since one of the aims of the clinician is to reduce costs and find more economic ways to raise patient satisfaction, this paper describes a practical method for chair-side fabrication of non-occlusal loaded provisional crowns used by the authors for several years successfully. METHODS: Twenty two patients (9 males, 13 females; mean age, 36,72 years) with one missing anterior tooth were treated by using the presented method. Metal definitive abutments instead of provisional abutments were used and provisional crowns were fabricated on the definitive abutments for all of the patients. The marginal fit was finished on a laboratory analogue and temporarily cemented to the abutments. The marginal adaptation of the crowns was evaluated radiographically. RESULTS: The patients were all satisfied with the final appearance and no complications occurred until the implants were loaded with permanent restorations. CONCLUSIONS: The use of the definitive abutments for provisional crowns instead of provisional abutments reduces the costs and the same results can be obtained.
Crowns ; Dental Abutments ; Dental Implants ; Dental Marginal Adaptation ; Dental Prosthesis ; Esthetics ; Humans ; Male ; Patient Satisfaction ; Tooth