Marwa Wahsh - Academia.edu (original) (raw)

Papers by Marwa Wahsh

Dental and Medical Problems, Sep 29, 2023

Background. Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium an... more Background. Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium and ceramic implant abutments due to its apparent ability to dissipate excessive strain around dental implants. However, the biomechanical behaviors of implant abutment crown systems may change depending on the crown and abutment material combinations used. Objectives. This study aimed to assess how the crown material affects strain generation and fracture resistance of PEKK hybrid abutment crowns. Material and methods. Sixteen dummy implants (Ø 3.7 × 11 mm), simulating maxillary first premolars, were restored with 16 milled PEKK hybrid abutments and randomly categorized into two groups according to the crown material (n = 8): Group C, milled composite crowns cemented on PEKK hybrid abutments; and Group Z, ultra-translucent zirconia crowns cemented on PEKK hybrid abutments. Before thermocycling, a cyanoacrylate-base adhesive was used to position two strain gauges on buccal and lingual crestal bone surfaces, and a vertical load (100 N) was applied to the central fossa to record the strain generated. Then, all samples were thermocycled between 5°C and 55°C before being loaded to fracture on a universal testing machine. Modes of failure were observed under an optical microscope, and representative samples were examined using a scanning electron microscope. Independent t-tests were used for intergroup comparisons. The significance level was set at (p < 0.05) for all tests.. Results. The results showed a significant difference between both groups. The zirconia group recorded significantly higher strain and fracture resistance values than the composite group (p < 0.001). There was a positive correlation between the strain developed in peri-implant crestal bone and fracture resistance of the abutment crown complex. Conclusions. Strains developed in both groups were within the acceptable clinical range. The crown material substantially impacted the strain and fracture of the PEKK hybrid abutment crown system.

Journal of prosthodontics, Jul 10, 2024

Egyptian Dental Journal /Egyptian Dental Journal, Jul 1, 2024

Purpose: To establish and verify new digital technique to standardize endocrown preparations usin... more Purpose: To establish and verify new digital technique to standardize endocrown preparations using CAD/CAM. Material and Methods: Ten recently extracted intact maxillary premolars were selected in this study. All teeth received standardized endodontic treatment. A standard 3D virtual designed cavity preparation was selected with specific dimensions. This preparation was sent to CAD software as STL file. All teeth samples were held within milling machine using special design attachment. All teeth were then scanned using trios 3. The scanned teeth were checked for trueness using 3D comparing engineering software by superimposition of the virtual model STL file as a control model to each STL file of the ten scanned teeth. Results: The total similarities and differences between 3D designed cavity preparations from Rhinoceros software were compared with the STL files of scanned specimens. The mean difference between the samples and the reference was 0.093 millimeters. Conclusion: 1) The mean trueness of all teeth samples was quantitively within the acceptable range (+100 ___-100 micron), considering clinically relevant threshold in literature, 2) Qualitatively, the pulpal floor showed the most uneven deviation pattern.

Al-Azhar Journal of Dental Science, Dec 31, 2023

Objective: This study was designed to evaluate different surface treatments affecting bond streng... more Objective: This study was designed to evaluate different surface treatments affecting bond strength of different lithium silicate ceramics, due to long-term survival of adhesive esthetic restorations greatly depends on achieving maximum adhesive bonding strength, however one of the most common failures is loss of retention &de-bonding of ceramic restorations. Materials and methods: Total number of 42 lithium silicate squared samples were fabricated with a dimension of 1 cm 2 , categorized as two groups (N=21) according to the two different materials. (Obsidian and Vita Suprinity). Every group of them receives three different types of surface treatments: acid etch, sand blasting and laser then all samples were bonded using a resin cement (RC) to a composite substrate. After that, all samples were subjected to thermocycling. Shear bond strength was assessed using a universal test machine while the surface treatment effect on the ceramic surface was observed by scanning electron microscope (SEM). Results: This study revealed that acid etching gave superior bonding strength (8.91±2.42 A a for Obsidian and 9.05±2.87 A a for Suprinity) in comparison to sandblasting (6.94±1.1 A a for Obsidian and 6.81 ± 1.14 AB a for Suprinity), yet Laser gave the least results (4.16±0.83 B a for Obsidian and 3.94±1.1 B a for Suprinity). Conclusion: Acid etching is the best surface treatment to be used with Lithium silicate ceramics concerning bond strength, Sandblasting could be used for much less retention, while Laser at the used parameters shouldn't be used as a surface treatment for Lithium silicate ceramics.

International Journal of Applied Dental Sciences, Dec 31, 2023

Ain Shams Dental Journal, Feb 28, 2023

Dental and Medical Problems, Sep 29, 2023

BMC oral health, May 15, 2024

Ain Shams Dental Journal, Jun 1, 2018

BMC Oral Health

Objectives Evaluating the bond strength of two ceramic materials to dentin after Er,Cr:YSGG laser... more Objectives Evaluating the bond strength of two ceramic materials to dentin after Er,Cr:YSGG laser debonding. Would laser debonding affect the bond strength of ceramic to dentin? Materials and methods Recently extracted human molars were ground to expose dentin. Forty square shaped samples were prepared from CAD/CAM ceramic blocks. Samples were divided into two groups according to the type of ceramic material; group E: Lithium disilicate and group T: Ultra-translucent Zirconia (n = 20) Each group was divided into two subgroups (n = 10) according to the laser debonding effect (subgroup B: bonded samples, subgroup R: re-bonded samples after laser debonding). Ceramic samples were bonded to dentin using dual cure self-adhesive resin cement. Laser debonding of ceramic samples of subgroups R using Er, Cr:YSGG laser, were then re-bonded again to dentin surface with same resin cement. The Shear bond strength test using Universal testing machine was done. The failure mode was analyzed. Two-wa...

Future Dental Journal, 2018

The objective of the study was to investigate the effect of different immersion times, in colorin... more The objective of the study was to investigate the effect of different immersion times, in coloring liquid, and sintering temperatures on translucency of monolithic nanocrystalline zirconia. Materials and methods: Forty five specimens of nanocrystalline zirconia were obtained by cutting InCoris TZI blocks into slices using a stainless steel disc mounted on a custom made milling machine. The slices were divide into three groups (n ¼ 15) according to immersion times (3,5 and 7 min) then each group was further subdivided into 3 subgroups (n ¼ 5) according to the sintering temperatures (1400 c, 1500 c and 1600 c). CIE-Lab coordinates were measured for each slice against black and white backgrounds using Vita easy shade spectrophotometer and translucency parameter (TP) was calculated. One way analysis of variance combined with a Tukey-post hoc test were used to analyze the data obtained (P ¼ 0.05). Results: Results of the present study showed that at temperature 1400 c there was statistically significant decrease in TP between 7 min immersion time and the other two groups, while there was no statistically significant difference in TP using different immersion times at temperatures 1500 c and 1600 c. Conclusion: Our results showed that the best translucency was obtained by the combination between lower dipping times and higher sintering holding temperatures.

Future Dental Journal, 2016

The objective of the study was to evaluate the translucency of different thickness of a transluce... more The objective of the study was to evaluate the translucency of different thickness of a translucent zirconia before and after accelerated aging. Materials and methods: Sixty slices of translucent zirconia were obtained by cutting InCoris TZI blocks into slices using Micracut precision cutting machine. The slices were divide into four groups (n ¼ 15) according to their thickness (0.5 mm, 0.8 mm, 1 mm and 1.2 mm). CIE lab coordinates were measured for each slice against black and white backgrounds using vita easy shade and TP was calculated. All specimens were subjected to accelerated aging using autoclave (134 ºC, 0.2 MPa) and TP was calculated after accelerated aging. One way analysis of variance combined with a Tukey-post hoc test was used to analyze the data obtained (P ¼ 0.05). Results: Results of the present study showed that thickness of zirconia has determinal effect on its translucency as there was no statistically significant difference in TP between 0.5 mm and 0.8 mm thicknesses while there were statistically significant differences in TP between 0.8 mm, 1.0 mm, 1.2 mm. Effect of aging was significant on 0.5 mm thickness. Conclusion: Thickness of zirconia has significant effect on translucency. Aging has significant effect on thinner sections of zirconia. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.

Egyptian Dental Journal

Objectives: To investigate and compare the color stability and surface roughness of provisional r... more Objectives: To investigate and compare the color stability and surface roughness of provisional restorative materials fabricated by 3D printing, milling and conventional techniques after immersion in different storage media. Materials and methods: The 84-disc specimens were fabricated and divided into 3 groups according to the technique of fabrication (n=28), group C: Conventional techniques, group M: milled technique, group P: 3d printed technique. Each group was divided into 4 subgroups according to storage media (n=7), Subgroup D: distilled water, subgroup C: coffee solution, subgroup Co: cola, and subgroup O: orange juice. Baseline color was measured using spectrophotometer then measured after 2 and 4 weeks of immersion in different storage media. Color change (ΔE) was assessed using of the CIE L*a*b* system. Surface roughness was also measured using profilometer for all specimens before and after immersion in staining solutions. The data was then collected and statistically analyzed using two-way ANOVA. The significance level was set at p<0.05 within all tests. Results: Two-way ANOVA showed that the fabrication technique and interaction between variables had a significant effect on surface roughness. There was a significant interaction between fabrication method, solution type and storage time on color stability. Conclusions: The surface roughness of 3D printed materials was higher than milled and conventional groups. 3D printed and CAD-CAM milled materials had better color stability compared to conventional group.

Egyptian Dental Journal

Statement of problem: The translucency of cubic zirconia is improved on the expense of its streng... more Statement of problem: The translucency of cubic zirconia is improved on the expense of its strength. The effect of grinding and finishing on its mechanical properties is still unclear. Purpose: The aim of this study was to evaluate the influence of glazing and polishing protocols on the surface roughness and flexural strength of monolithic cubic zirconia after dry and wet grinding. Materials and methods: Super translucent multilayer zirconia (STML) disks were cut, sintered, and glazed according to the manufacturer's recommendations. Samples were randomly divided into three groups according to surface grinding: Group (C): control (no grinding-as glazed), Group (D)grinding under dry condition and group (W) grinding under wet condition. Each group of (D)and(W) was subdivided into two subgroups according to surface finishing whether glazing or polishing. The roughness average (Ra) was measured using contact profilometer. Biaxial flexural strength test was done using a universal testing machine. Statistical analysis was performed. Results: The glazing showed a statistically significantly higher mean Ra (P<0.05) than polishing whether after wet or dry grinding. The dry ground groups showed a statistically significantly higher mean Ra (P<0.05) than wet ground groups. The glazing showed a statistically significantly lower mean biaxial flexural strength than Polishing (P<0.05) after dry grinding. While there was no statistically significant difference between glazing and polishing (P>0.05) after wet grinding. Conclusion: Adequate polishing can produce a smoother surface than reglazing. Dry grinding can increase the surface roughness to a degree that can affect the flexural strength of STML zirconia.

Egyptian Dental Journal

Objectives: Comparing debonding time of three different ceramic materials lithium disilicate, ult... more Objectives: Comparing debonding time of three different ceramic materials lithium disilicate, ultra-translucent zirconia and hybrid-ceramic with dentin using Er, Cr:YSGG laser application. Materials and methods: Thirty recently extracted human mandibular molars were selected for study. They were fixed in acrylic resin blocks and their buccal surfaces were ground to expose dentin to provide flat surface for bonding then stored in distilled water at room temperature. Three different ceramic materials used in this study, lithium disilicate glass ceramics, hybrid-ceramic, ultra-Translucent Zirconia. A total of thirty square shaped Samples 4x4mm and 1mm thickness resembling crowns prepared from CAD/CAM (computer aided design/computer aided manufacture) ceramic blocks of these ceramic materials, 10 samples for each material. Samples bonded to dentin using dual cure self-adhesive resin cement (TOTALCEM ITENA, France). Laser debonding of ceramic samples of all three materials using Er,Cr:YSGG laser (Waterlase by Biolase). Data were parametric and showed variance homogeneity, so they were analyzed using independent t-test. The significance level was set at p<0.05 within all tests. Results: Results showed that there was a significant difference between different groups (p<0.001). The highest value was found in Vita Enamic samples (160.00±22.91) followed by BruxZir (21.57±5.26), while the lowest value was found in Emax samples (7.00±1.29). Conclusions: The Ultra translucent zirconia and Lithium disilicate were deboned from dentin using Er,Cr:YSGG laser. Using laser for debonding Ultra translucent Zirconia consumses higher time than for Lithium disilicate. Destruction of hybrid ceramics when it was exposed to Er,Cr:YSGG laser to debond it from dentin.

Ain Shams Dental Journal, 2021

Purpose: To assess the surface roughness of two of CAD/CAM Ceramic materials: Lithium disilicate ... more Purpose: To assess the surface roughness of two of CAD/CAM Ceramic materials: Lithium disilicate and Resin nanoceramic, after being stored in three media: Instant coffee, Citric Acid and Artificial saliva. Materials and methods: A total number of 42 slices cut by low speed diamond saw with water coolant of IPS e.max CAD & Cerasmart ceramic blocks (n=21 for each material) and shade A3. The samples were divided into three subgroups (n=7 for each storage medium): Sub-Group 1: stored in instant coffee, Sub-Group 2: stored in citric acid, SubGroup 3: stored in artificial saliva. All samples were subjected to thermocycling at 5000 cycles between 5 and 55 degrees in deionized water with a dwell time of 30 seconds, and transfer time of 10 seconds. Surface roughness values were determined by a surface Profilometer. The data were analyzed using One Way ANOVA test followed by Tukey`s Post Hok test for multiple comparisons. The significant level was set at P ≤ 0.05. Results: Immersion in differ...

Ain Shams Dental Journal, 2021

Aim: The objective of the current study is to evaluate the water sorption of resin cement under t... more Aim: The objective of the current study is to evaluate the water sorption of resin cement under three types of ceramic material (Lithium di-silicate, Vita Enamic & Cerasmart) Using two thicknesses (0.4 & 1mm). Methodology: Forty-two specimens will be sliced with two thicknesses (0.4 & 1mm) from Lithium di-silicate (e-max), Resin reinforced lithium di-silicate (vita Enamic), and Cerasmart blocks. Then water sorption of resin cement will be evaluated after curing through each specimen using a digital weight caliper. Results: Results showed a significant difference in water sorption between different materials, the lowest water sorption of resin cement was found under lithium disilicate (e.max) than that of Vita Enamic and Cerasmart samples. There wasn’t a significant difference between different thicknesses of Vita Enamic and Cerasmart blocks, However, in Emax samples, 1.0 mm thick samples had significantly higher water sorption values than samples with 0.4 mm thickness. Conclusion: W...

Ain Shams Dental Journal, 2021

Dental and Medical Problems, Sep 29, 2023

Background. Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium an... more Background. Polyetherketoneketone (PEKK) was recently introduced as an alternative to titanium and ceramic implant abutments due to its apparent ability to dissipate excessive strain around dental implants. However, the biomechanical behaviors of implant abutment crown systems may change depending on the crown and abutment material combinations used. Objectives. This study aimed to assess how the crown material affects strain generation and fracture resistance of PEKK hybrid abutment crowns. Material and methods. Sixteen dummy implants (Ø 3.7 × 11 mm), simulating maxillary first premolars, were restored with 16 milled PEKK hybrid abutments and randomly categorized into two groups according to the crown material (n = 8): Group C, milled composite crowns cemented on PEKK hybrid abutments; and Group Z, ultra-translucent zirconia crowns cemented on PEKK hybrid abutments. Before thermocycling, a cyanoacrylate-base adhesive was used to position two strain gauges on buccal and lingual crestal bone surfaces, and a vertical load (100 N) was applied to the central fossa to record the strain generated. Then, all samples were thermocycled between 5°C and 55°C before being loaded to fracture on a universal testing machine. Modes of failure were observed under an optical microscope, and representative samples were examined using a scanning electron microscope. Independent t-tests were used for intergroup comparisons. The significance level was set at (p < 0.05) for all tests.. Results. The results showed a significant difference between both groups. The zirconia group recorded significantly higher strain and fracture resistance values than the composite group (p < 0.001). There was a positive correlation between the strain developed in peri-implant crestal bone and fracture resistance of the abutment crown complex. Conclusions. Strains developed in both groups were within the acceptable clinical range. The crown material substantially impacted the strain and fracture of the PEKK hybrid abutment crown system.

Journal of prosthodontics, Jul 10, 2024

Egyptian Dental Journal /Egyptian Dental Journal, Jul 1, 2024

Purpose: To establish and verify new digital technique to standardize endocrown preparations usin... more Purpose: To establish and verify new digital technique to standardize endocrown preparations using CAD/CAM. Material and Methods: Ten recently extracted intact maxillary premolars were selected in this study. All teeth received standardized endodontic treatment. A standard 3D virtual designed cavity preparation was selected with specific dimensions. This preparation was sent to CAD software as STL file. All teeth samples were held within milling machine using special design attachment. All teeth were then scanned using trios 3. The scanned teeth were checked for trueness using 3D comparing engineering software by superimposition of the virtual model STL file as a control model to each STL file of the ten scanned teeth. Results: The total similarities and differences between 3D designed cavity preparations from Rhinoceros software were compared with the STL files of scanned specimens. The mean difference between the samples and the reference was 0.093 millimeters. Conclusion: 1) The mean trueness of all teeth samples was quantitively within the acceptable range (+100 ___-100 micron), considering clinically relevant threshold in literature, 2) Qualitatively, the pulpal floor showed the most uneven deviation pattern.

Al-Azhar Journal of Dental Science, Dec 31, 2023

Objective: This study was designed to evaluate different surface treatments affecting bond streng... more Objective: This study was designed to evaluate different surface treatments affecting bond strength of different lithium silicate ceramics, due to long-term survival of adhesive esthetic restorations greatly depends on achieving maximum adhesive bonding strength, however one of the most common failures is loss of retention &de-bonding of ceramic restorations. Materials and methods: Total number of 42 lithium silicate squared samples were fabricated with a dimension of 1 cm 2 , categorized as two groups (N=21) according to the two different materials. (Obsidian and Vita Suprinity). Every group of them receives three different types of surface treatments: acid etch, sand blasting and laser then all samples were bonded using a resin cement (RC) to a composite substrate. After that, all samples were subjected to thermocycling. Shear bond strength was assessed using a universal test machine while the surface treatment effect on the ceramic surface was observed by scanning electron microscope (SEM). Results: This study revealed that acid etching gave superior bonding strength (8.91±2.42 A a for Obsidian and 9.05±2.87 A a for Suprinity) in comparison to sandblasting (6.94±1.1 A a for Obsidian and 6.81 ± 1.14 AB a for Suprinity), yet Laser gave the least results (4.16±0.83 B a for Obsidian and 3.94±1.1 B a for Suprinity). Conclusion: Acid etching is the best surface treatment to be used with Lithium silicate ceramics concerning bond strength, Sandblasting could be used for much less retention, while Laser at the used parameters shouldn't be used as a surface treatment for Lithium silicate ceramics.

International Journal of Applied Dental Sciences, Dec 31, 2023

Ain Shams Dental Journal, Feb 28, 2023

Dental and Medical Problems, Sep 29, 2023

BMC oral health, May 15, 2024

Ain Shams Dental Journal, Jun 1, 2018

BMC Oral Health

Objectives Evaluating the bond strength of two ceramic materials to dentin after Er,Cr:YSGG laser... more Objectives Evaluating the bond strength of two ceramic materials to dentin after Er,Cr:YSGG laser debonding. Would laser debonding affect the bond strength of ceramic to dentin? Materials and methods Recently extracted human molars were ground to expose dentin. Forty square shaped samples were prepared from CAD/CAM ceramic blocks. Samples were divided into two groups according to the type of ceramic material; group E: Lithium disilicate and group T: Ultra-translucent Zirconia (n = 20) Each group was divided into two subgroups (n = 10) according to the laser debonding effect (subgroup B: bonded samples, subgroup R: re-bonded samples after laser debonding). Ceramic samples were bonded to dentin using dual cure self-adhesive resin cement. Laser debonding of ceramic samples of subgroups R using Er, Cr:YSGG laser, were then re-bonded again to dentin surface with same resin cement. The Shear bond strength test using Universal testing machine was done. The failure mode was analyzed. Two-wa...

Future Dental Journal, 2018

The objective of the study was to investigate the effect of different immersion times, in colorin... more The objective of the study was to investigate the effect of different immersion times, in coloring liquid, and sintering temperatures on translucency of monolithic nanocrystalline zirconia. Materials and methods: Forty five specimens of nanocrystalline zirconia were obtained by cutting InCoris TZI blocks into slices using a stainless steel disc mounted on a custom made milling machine. The slices were divide into three groups (n ¼ 15) according to immersion times (3,5 and 7 min) then each group was further subdivided into 3 subgroups (n ¼ 5) according to the sintering temperatures (1400 c, 1500 c and 1600 c). CIE-Lab coordinates were measured for each slice against black and white backgrounds using Vita easy shade spectrophotometer and translucency parameter (TP) was calculated. One way analysis of variance combined with a Tukey-post hoc test were used to analyze the data obtained (P ¼ 0.05). Results: Results of the present study showed that at temperature 1400 c there was statistically significant decrease in TP between 7 min immersion time and the other two groups, while there was no statistically significant difference in TP using different immersion times at temperatures 1500 c and 1600 c. Conclusion: Our results showed that the best translucency was obtained by the combination between lower dipping times and higher sintering holding temperatures.

Future Dental Journal, 2016

The objective of the study was to evaluate the translucency of different thickness of a transluce... more The objective of the study was to evaluate the translucency of different thickness of a translucent zirconia before and after accelerated aging. Materials and methods: Sixty slices of translucent zirconia were obtained by cutting InCoris TZI blocks into slices using Micracut precision cutting machine. The slices were divide into four groups (n ¼ 15) according to their thickness (0.5 mm, 0.8 mm, 1 mm and 1.2 mm). CIE lab coordinates were measured for each slice against black and white backgrounds using vita easy shade and TP was calculated. All specimens were subjected to accelerated aging using autoclave (134 ºC, 0.2 MPa) and TP was calculated after accelerated aging. One way analysis of variance combined with a Tukey-post hoc test was used to analyze the data obtained (P ¼ 0.05). Results: Results of the present study showed that thickness of zirconia has determinal effect on its translucency as there was no statistically significant difference in TP between 0.5 mm and 0.8 mm thicknesses while there were statistically significant differences in TP between 0.8 mm, 1.0 mm, 1.2 mm. Effect of aging was significant on 0.5 mm thickness. Conclusion: Thickness of zirconia has significant effect on translucency. Aging has significant effect on thinner sections of zirconia. More research is required on zirconia towards making the material more translucent for its potential use as esthetic monolithic restoration.

Egyptian Dental Journal

Objectives: To investigate and compare the color stability and surface roughness of provisional r... more Objectives: To investigate and compare the color stability and surface roughness of provisional restorative materials fabricated by 3D printing, milling and conventional techniques after immersion in different storage media. Materials and methods: The 84-disc specimens were fabricated and divided into 3 groups according to the technique of fabrication (n=28), group C: Conventional techniques, group M: milled technique, group P: 3d printed technique. Each group was divided into 4 subgroups according to storage media (n=7), Subgroup D: distilled water, subgroup C: coffee solution, subgroup Co: cola, and subgroup O: orange juice. Baseline color was measured using spectrophotometer then measured after 2 and 4 weeks of immersion in different storage media. Color change (ΔE) was assessed using of the CIE L*a*b* system. Surface roughness was also measured using profilometer for all specimens before and after immersion in staining solutions. The data was then collected and statistically analyzed using two-way ANOVA. The significance level was set at p<0.05 within all tests. Results: Two-way ANOVA showed that the fabrication technique and interaction between variables had a significant effect on surface roughness. There was a significant interaction between fabrication method, solution type and storage time on color stability. Conclusions: The surface roughness of 3D printed materials was higher than milled and conventional groups. 3D printed and CAD-CAM milled materials had better color stability compared to conventional group.

Egyptian Dental Journal

Statement of problem: The translucency of cubic zirconia is improved on the expense of its streng... more Statement of problem: The translucency of cubic zirconia is improved on the expense of its strength. The effect of grinding and finishing on its mechanical properties is still unclear. Purpose: The aim of this study was to evaluate the influence of glazing and polishing protocols on the surface roughness and flexural strength of monolithic cubic zirconia after dry and wet grinding. Materials and methods: Super translucent multilayer zirconia (STML) disks were cut, sintered, and glazed according to the manufacturer's recommendations. Samples were randomly divided into three groups according to surface grinding: Group (C): control (no grinding-as glazed), Group (D)grinding under dry condition and group (W) grinding under wet condition. Each group of (D)and(W) was subdivided into two subgroups according to surface finishing whether glazing or polishing. The roughness average (Ra) was measured using contact profilometer. Biaxial flexural strength test was done using a universal testing machine. Statistical analysis was performed. Results: The glazing showed a statistically significantly higher mean Ra (P<0.05) than polishing whether after wet or dry grinding. The dry ground groups showed a statistically significantly higher mean Ra (P<0.05) than wet ground groups. The glazing showed a statistically significantly lower mean biaxial flexural strength than Polishing (P<0.05) after dry grinding. While there was no statistically significant difference between glazing and polishing (P>0.05) after wet grinding. Conclusion: Adequate polishing can produce a smoother surface than reglazing. Dry grinding can increase the surface roughness to a degree that can affect the flexural strength of STML zirconia.

Egyptian Dental Journal

Objectives: Comparing debonding time of three different ceramic materials lithium disilicate, ult... more Objectives: Comparing debonding time of three different ceramic materials lithium disilicate, ultra-translucent zirconia and hybrid-ceramic with dentin using Er, Cr:YSGG laser application. Materials and methods: Thirty recently extracted human mandibular molars were selected for study. They were fixed in acrylic resin blocks and their buccal surfaces were ground to expose dentin to provide flat surface for bonding then stored in distilled water at room temperature. Three different ceramic materials used in this study, lithium disilicate glass ceramics, hybrid-ceramic, ultra-Translucent Zirconia. A total of thirty square shaped Samples 4x4mm and 1mm thickness resembling crowns prepared from CAD/CAM (computer aided design/computer aided manufacture) ceramic blocks of these ceramic materials, 10 samples for each material. Samples bonded to dentin using dual cure self-adhesive resin cement (TOTALCEM ITENA, France). Laser debonding of ceramic samples of all three materials using Er,Cr:YSGG laser (Waterlase by Biolase). Data were parametric and showed variance homogeneity, so they were analyzed using independent t-test. The significance level was set at p<0.05 within all tests. Results: Results showed that there was a significant difference between different groups (p<0.001). The highest value was found in Vita Enamic samples (160.00±22.91) followed by BruxZir (21.57±5.26), while the lowest value was found in Emax samples (7.00±1.29). Conclusions: The Ultra translucent zirconia and Lithium disilicate were deboned from dentin using Er,Cr:YSGG laser. Using laser for debonding Ultra translucent Zirconia consumses higher time than for Lithium disilicate. Destruction of hybrid ceramics when it was exposed to Er,Cr:YSGG laser to debond it from dentin.

Ain Shams Dental Journal, 2021

Purpose: To assess the surface roughness of two of CAD/CAM Ceramic materials: Lithium disilicate ... more Purpose: To assess the surface roughness of two of CAD/CAM Ceramic materials: Lithium disilicate and Resin nanoceramic, after being stored in three media: Instant coffee, Citric Acid and Artificial saliva. Materials and methods: A total number of 42 slices cut by low speed diamond saw with water coolant of IPS e.max CAD & Cerasmart ceramic blocks (n=21 for each material) and shade A3. The samples were divided into three subgroups (n=7 for each storage medium): Sub-Group 1: stored in instant coffee, Sub-Group 2: stored in citric acid, SubGroup 3: stored in artificial saliva. All samples were subjected to thermocycling at 5000 cycles between 5 and 55 degrees in deionized water with a dwell time of 30 seconds, and transfer time of 10 seconds. Surface roughness values were determined by a surface Profilometer. The data were analyzed using One Way ANOVA test followed by Tukey`s Post Hok test for multiple comparisons. The significant level was set at P ≤ 0.05. Results: Immersion in differ...

Ain Shams Dental Journal, 2021

Aim: The objective of the current study is to evaluate the water sorption of resin cement under t... more Aim: The objective of the current study is to evaluate the water sorption of resin cement under three types of ceramic material (Lithium di-silicate, Vita Enamic & Cerasmart) Using two thicknesses (0.4 & 1mm). Methodology: Forty-two specimens will be sliced with two thicknesses (0.4 & 1mm) from Lithium di-silicate (e-max), Resin reinforced lithium di-silicate (vita Enamic), and Cerasmart blocks. Then water sorption of resin cement will be evaluated after curing through each specimen using a digital weight caliper. Results: Results showed a significant difference in water sorption between different materials, the lowest water sorption of resin cement was found under lithium disilicate (e.max) than that of Vita Enamic and Cerasmart samples. There wasn’t a significant difference between different thicknesses of Vita Enamic and Cerasmart blocks, However, in Emax samples, 1.0 mm thick samples had significantly higher water sorption values than samples with 0.4 mm thickness. Conclusion: W...

Ain Shams Dental Journal, 2021