scholarly journals A base-line study of the wear of burs used for chairside milling of ceramic crowns of different hardness: effect on internal fit and surface roughness

2020 ◽  
Author(s):  
Ayman Abd Alla Ahmed
Keyword(s):  
Surface Roughness ◽  
Tungsten Carbide ◽  
Diamond Particle ◽  
Base Line ◽  
Replica Technique ◽  
Before And After ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Internal Fit ◽  
And Tungsten

Abstract Background: In the CAD/CAM environment, wear of the milling burs may affect the accuracy of the milled crown. However, no studies have related bur wear to both the resultant internal fit of the crown or to the surface roughness. The aim of this study was to study this, using diamond burs and a feldspathic ceramic (Sirona Blocs C, Dentsply Sirona, Germany) and tungsten carbide burs and Zirconia (inCoris TZI puck, Dentsply Sirona, Germany).Methods: Thirty of each of the two materials were milled from the same standard preparation. One set of diamond burs was used for the feldspathic ceramic and one set of tungsten-carbide burs for the Zirconia. Before and after the 10th, 20th and 30th milling times, diamond particle loss was counted and cutting blade changes of the tungsten-carbide burs measured. Internal fit was measured using a silicone replica technique and surface roughness with a 3D measuring laser microscope.Results: Increasing wear of the diamond burs as measured by an average 26% loss of diamond particles after 30 crowns, which resulted in a 6% decrease in internal luting space and a 16% increase in surface roughness. Increasing wear of the tungsten-carbide burs resulted in a 13% decrease in the luting space, but there was an overall 16% increase in surface roughness. Conclusions: This is the first study to compare the wear of diamond and tungsten-carbide milling burs with the internal fit and surface roughness of the crown. The wear of milling burs affects the luting space, reducing it as the burs wear, and therefore the milling parameters must be adjusted to compensate for this.

scholarly journals A base-line study of the wear of burs used for chairside milling of ceramic crowns of different hardness: effect on internal fit and surface roughness

2020 ◽  
Vol 75 (10) ◽  
pp. 534-540
Author(s):  
Ayman A Ahmed ◽  
C Peter Owen
Keyword(s):  
Surface Roughness ◽  
Diamond Particle ◽  
Ceramic Materials ◽  
Base Line ◽  
Replica Technique ◽  
Particle Loss ◽  
Milling Parameters ◽  
Before And After ◽  
Ceramic Crowns ◽  
Internal Fit

INTRODUCTION: Wear of milling burs may affect the internal fit and surface roughness of the milled crown. AIM: To assess the wear of diamond and tungsten carbide (TC) burs from milling ceramic materials and the effect on internal fit and surface roughness. METHODS: Thirty crowns of each of the two materials were milled from the same standard preparation. Diamond burs were used for a feldspathic ceramic and TC burs for zirconia. Before and after the 10th, 20th and 30th milling, diamond particle loss was counted and cutting blade changes of the TC burs measured. Internal fit was measured using a silicone replica technique and surface roughness by 3D laser microscope. RESULTS: An average 26% loss of diamond particles occurred after 30 crowns, resulting in a 6% decrease in internal luting space and a 21% decrease in surface roughness. Wear of the TC burs resulted in a 13% decrease in the luting space, and a 16% increase in surface roughness. CONCLUSION: The wear of milling burs reduces the luting space, and the milling parameters must be adjusted to compensate for this. Surface roughness is affected by bur type: with diamond burs it decreased, and increased with TC burs.

scholarly journals Fit of metal-ceramic crowns

2021 ◽  
Vol 21 ◽  
pp. e225136
Author(s):  
Patrícia Valéria Manozzo Kunz ◽  
Gabriela Andrade Serpa ◽  
Leonardo Fernandes da Cunha ◽  
Gisele Maria Correr ◽  
Carla Castiglia Gonzaga
Keyword(s):  
Cobalt Chromium ◽  
Manufacturing Method ◽  
Significant Difference ◽  
Metal Ceramic ◽  
Before And After ◽  
Cad Cam ◽  
Marginal Discrepancy ◽  
Ceramic Crowns ◽  
Student’S T ◽  
Internal Fit

Aim: To evaluate the influence of cobalt-chromium (Co-Cr) coping fabrication methods and ceramic application on the marginal and internal fit of metal-ceramic crowns. Methods: Co-Cr copings for metal-ceramic crowns were prepared by lost wax casting or CAD-CAM machining of sintered blocks. The fit was analyzed using the silicone replica technique at four assessment points: marginal gap (MG), axial wall (AW), axio-occlusal (AO) angle, and central occlusal (CO) wall. After the initial analysis, the copings were ceramic-veneered with the layering technique, and the fit was again determined. Data were statistically analyzed by paired and unpaired Student’s-t test (α=0.05). Results: Marginal and internal fit before ceramic application according to the coping manufacturing method showed significant differences only at CO (p < 0.001), with milled copings (137.98±16.71 μm) showing higher gap values than cast copings (112.86±8.57 μm). For cast copings, there were significant differences at MG (before 109.13±8.79 μm; after 102.78±7.18 μm) and CO (before 112.86±8.57 μm; after 104.07±10.63 μm) when comparing the fit before and after ceramic firing. For milled copings, there was significant difference only at AO (before 116.39±9.64 μm; after 108.54±9.26 μm). Conclusion: This study demonstrated that the coping fabrication method influenced the internal fit. Ceramic firing maintained or improved the fit of the metal-ceramic crowns. The marginal discrepancy of all restorations, before and after ceramic firing, can be considered clinically acceptable.

Marginal and internal fit of CAD-CAM composite resin and ceramic crowns before and after internal adjustment

2020 ◽  
Vol 123 (3) ◽  
pp. 500-505 ◽  
Author(s):  
Lucas F. Tabata ◽  
Taiana A. de Lima Silva ◽  
Alessandra C. de Paula Silveira ◽  
Ana Paula D. Ribeiro
Keyword(s):  
Composite Resin ◽  
Before And After ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Internal Fit

scholarly journals Effect of the Crystallization Process on the Marginal and Internal Gaps of Lithium Disilicate CAD/CAM Crowns

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Jae-Hong Kim ◽  
Seunghan Oh ◽  
Soo-Hyuk Uhm
Keyword(s):  
Computer Aided Design ◽  
Crystallization Process ◽  
Lithium Disilicate ◽  
Mean Values ◽  
Computer Aided ◽  
Before And After ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Aided Design ◽  
Internal Fit

The aim of this study is to quantify the effect of the crystallization process on lithium disilicate ceramic crowns fabricated using a computer-aided design/computer-aided manufacturing (CAD/CAM) system and to determine whether the effect of crystallization is clinically acceptable by comparing values of fit before and after the crystallization process. The mandibular right first molar was selected as the abutment for the experiments. Fifteen working models were prepared. Lithium disilicate crowns appropriate for each abutment were prepared using a commercial CAD/CAM system. Gaps in the marginal area and 4 internal areas of each crown were measured twice—before and after crystallization—using the silicone replica technique. The mean values of fit before and after crystallization were analyzed using a pairedt-test to examine whether the conversion that occurred during crystallization affected marginal and internal gaps (α=0.05). Gaps increased in the marginal area and decreased in the internal areas after crystallization. There were statistically significant differences in all of the investigated areas (P<0.05). None of the values for marginal and internal fit of lithium disilicate CAD/CAM crowns after crystallization exceeded 120μm, which is the clinically acceptable threshold.

scholarly journals Marginal and Internal Fit of Ceramic Prostheses Fabricated from Different Chairside CAD/CAM Systems: An In Vitro Study

2021 ◽  
Vol 11 (2) ◽  
pp. 857
Author(s):  
Keunbada Son ◽  
Kyu-Bok Lee
Keyword(s):  
Computer Aided Design ◽  
In Vitro Study ◽  
Vitro Study ◽  
Marginal Gap ◽  
Significant Difference ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Internal Fit ◽  
Cam Systems

The purpose of this in vitro study was to evaluate marginal and internal fits of ceramic crowns fabricated with chairside computer-aided design and manufacturing (CAD/CAM) systems. An experimental model based on ISO 12836:2015 was digitally scanned with different intraoral scanners (Omnicam (CEREC), EZIS PO (DDS), and CS3500 (Carestream)). Ceramic crowns were fabricated using the CAD/CAM process recommended by each system (CEREC, EZIS, and Carestream systems; N = 15). The 3-dimensional (3D) marginal and internal fit of each ceramic crown was measured using a 3D inspection software (Geomagic control X). Differences among the systems and various measurements were evaluated using the Kruskal–Wallis test. Statistically significant differences were validated using pairwise comparisons (α = 0.05). Occlusal gaps in the CEREC, EZIS, and Carestream groups were 113.0, 161.3, and 438.2 µm, respectively (p < 0.001). The axial gaps were 83.4, 78.0, and 107.9 µm, respectively. The marginal gaps were 77.8, 99.3, and 60.6 µm, respectively, and the whole gaps were 85.9, 107.3, and 214.0 µm, respectively. Significant differences were observed with the EZIS system compared with the other two systems in terms of the marginal gap sizes. The CEREC system showed no significant differences among the four measured regions. However, the EZIS and Carestream systems did show a statistically significant difference (p < 0.05). All three systems were judged to be capable of fabricating clinically acceptable prostheses, because the marginal gap, which is the most important factor in the marginal fit of prostheses, was recorded to be below 100 µm in all three systems.

scholarly journals In Vitro Study on Marginal and Internal Fit of CAD/CAM All-ceramic Crowns

2005 ◽  
Vol 24 (3) ◽  
pp. 456-459 ◽  
Author(s):  
Takashi NAKAMURA ◽  
Hideaki TANAKA ◽  
Soichiro KINUTA ◽  
Takeshi AKAO ◽  
Kei OKAMOTO ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Vitro Study ◽  
All Ceramic ◽  
Cad Cam ◽  
Ceramic Crowns ◽  
Internal Fit

scholarly journals Effect of Thermocycling, Surface Treatments and Microstructure on the Optical Properties and Roughness of CAD-CAM and Heat-Pressed Glass Ceramics

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 381 ◽  
Author(s):  
Roxana-Diana Vasiliu ◽  
Sorin Daniel Porojan ◽  
Mihaela Ionela Bîrdeanu ◽  
Liliana Porojan
Keyword(s):  
Surface Roughness ◽  
Optical Properties ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Lithium Disilicate ◽  
Ceramic Materials ◽  
Surface Treatments ◽  
Lithium Silicate ◽  
Before And After ◽  
Cad Cam

Dental ceramic restorations are widely spread nowadays due to their aesthetics and biocompatibility. In time, the colour and structure of these ceramic materials can be altered by aging processes. How does artificial aging affect the optical and surface roughness of ceramics? This study aims to assess the effect of thermocycling, surface treatments and microstructure upon translucency, opalescence and surface roughness on CAD-CAM and heat-pressed glass-ceramic. Forty-eight samples (1.5 mm thickness) were fabricated from six types of A2 MT ceramic: heat-pressed and milled glass-ceramic (feldspathic, lithium disilicate and zirconia reinforced lithium silicate). The samples were obtained respecting the manufacturer’s instructions. The resulted surfaces (n = 96) were half glazed and half polished. The samples were subjected to thermocycling (10,000 cycles) and roughness values (Ra and Rz), colour coordinates (L*, a*, b*) and microstructural analyses were assessed before and after thermocycling. Translucency (TP) and opalescence (OP) were calculated. Values were statistically analysed using ANOVA test (one way). TP and OP values were significantly different between heat-pressed and milled ceramics before and also after thermocycling (p < 0.001). Surface treatments (glazing and polishing) had a significant effect on TP and OP and surface roughness (p < 0.05). The heat-pressed and milled zirconia reinforced lithium silicate glass-ceramic experienced a loss in TP and OP. Ra and Rz increased for the glazed samples, TP and OP decreased for all the samples after thermocycling. Microstructural analyse revealed that glazed surfaces were more affected by the thermocycling and especially for the zirconia reinforced lithium silicate ceramic. Optical properties and surface roughness of the chosen ceramic materials were affected by thermocycling, surface treatments and microstructural differences. The least affected of the ceramics was the lithium disilicate ceramic heat-pressed polished and glazed.

scholarly journals New Intraoral Scanner-Based Chairside Measurement Method to Investigate the Internal Fit of Crowns: A Clinical Trial

2020 ◽  
Vol 17 (7) ◽  
pp. 2182 ◽  
Author(s):  
Maximiliane Amelie Schlenz ◽  
Jonas Vogler ◽  
Alexander Schmidt ◽  
Peter Rehmann ◽  
Bernd Wöstmann
Keyword(s):  
Evaluation Methods ◽  
Replica Method ◽  
P Value ◽  
Intraoral Scanner ◽  
Replica Technique ◽  
Target Parameter ◽  
Computer Aided ◽  
Cad Cam ◽  
Internal Fit ◽  
Internal Gap

To measure the internal fit of the computer-aided designed/computer-aided manufactured (CAD/CAM) crowns, a new scanner-based chairside approach was investigated in patients, and the results were compared to the established silicone replica technique and a digital laboratory replica method. Thirty full-coverage crown preparations were included. Based on a digital impression with an intraoral scanner (IOS, Trios 3), three CAD/CAM measurement copings (‘COM’, resin composite; ‘ZIR’, zirconium dioxide; ‘NPA’, non-precious alloy) were fabricated for each tooth preparation. The internal fit of the measurement copings was analyzed with three different evaluation methods: IOS-based digital approach (D-IOS), digital replica method with laboratory software (D-GOM), and conventional silicone replica technique (CV-SR). The congruence between the determined target parameter of the 80-µm cement space and the actual measured internal gap was investigated. Statistical analysis was performed by ANOVA (p-value < 0.05). No significant difference was determined between the three evaluation methods. However, significant differences were observed for the three coping materials (p-value < 0.05), the single measurement position (marginal, axial, and occlusal fit) (p-value < 0.05), and the interaction between the coping material and the measurement position (p-value < 0.05). COM revealed the smallest internal gap, followed by ZIR and NPA. Regardless of the coping material, the occlusal gap was higher than the axial and marginal gaps. Furthermore, only the internal gaps of the marginal area almost matched the target parameter of 80-µm for the cement space. D-IOS is effective for measuring internal fit of single crowns in different clinical settings.

Effect of Finishing and Polishing on the Surface Roughness and Gloss of Feldspathic Ceramic for Chairside CAD/CAM Systems

2017 ◽  
Vol 42 (2) ◽  
pp. 175-184 ◽  
Author(s):  
M Carrabba ◽  
A Vichi ◽  
G Vultaggio ◽  
S Pallari ◽  
R Paravina ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Flat Surface ◽  
Paper Surface ◽  
Before And After ◽  
Cad Cam ◽  
Ceramic Blocks ◽  
The Mean ◽  
Silicone Carbide ◽  
Cam Systems ◽  
Scanning Electron

SUMMARY Objectives: To evaluate surface roughness and gloss of feldspathic ceramic blocks for chairside CAD/CAM systems before and after finishing and polishing. Methods: VITA Mark II ceramic blocks for the CEREC CAD/CAM system were cut perpendicularly in order to obtain a total of 70 specimens (14 × 18 × 3 mm). The flat surface was roughened using a grinder/polisher with dry 120-grit silicone-carbide paper. Surface roughness and gloss were measured using a digital profilometer (Ra) and a glossmeter (GU), respectively. Specimens were randomly divided into seven groups (n=10) based on the finishing/polishing system as follows: 1) Identoflex NGPorcelain Polisher (INP), 2) Identoflex Diamond Ceramic Polisher (IDP), 3) Hiluster Polishing System (HPS), 4) OptraFine (OF), 5) Identoflex Lucent (IL), 6) VITA Akzent Glaze Spray (AGS), and 7) VITA Shading Paste and Liquid (SPL). Surface analysis was repeated after the finishing/polishing treatment, and the obtained data were compared to the baseline in order to evaluate the ΔRa and ΔGU. Results were statistically analyzed. The surface morphology was observed by scanning electron microscopy. Results: The mean surface roughness of polished systems increased in the order (statistical groups designated) SPLa &lt; ILa &lt; OFab &lt; IDPbc &lt; AGSbc &lt; INPbc &lt; HPSc and mean gloss decreased in the order AGSa &gt; SPLa &gt; OFab &gt; ILabc &gt; HPSbcd &gt; INPcd &gt; IDPd. Conclusions: The smoothest surface of CAD/CAM feldspathic ceramic blocks was achieved using the furnace-based glaze systems VITA Akzent Glaze Spray and VITA Shading Paste and Liquid and manual systems Identoflex Lucent and OptraFine.

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