Papers by Dr Hamada Z Mahross
Journal of Prosthodontic , 2024
Abstract
Purpose: To analyze the distribution of stresses for mandibular Kennedy class I removab... more Abstract
Purpose: To analyze the distribution of stresses for mandibular Kennedy class I removable partial overdentures submitted to different implant lengths and clasp designs.
Materials and methods: Twenty-seven heat-cured acrylic resin casts with a uniform soft acrylic layer were constructed from models representing the mandibular Kennedy class I removable partial denture with the first premolars terminal abutment on both sides. The casts were grouped into a control group, group I, and group II with three casts of each for designing a different clasp on the last abutment with Rest, Proximal plate, Aker circumferential (RPA), Rest, Proximal plate, I-bar (RPI), and wrought wire (WW). All casts were submitted to vertical load for stress analysis after preparing channels at the buccal/distal surface of abutments, the crest of the ridge, and the buccal/lingual of the implant for placement of uniaxial strain gauges that can convert the electro-signals to micro-strain by using the software. Kolmogorov-Smirnov normality test, independent t-test, and one-way anlysis of Variance (ANOVA) test followed by Tukey`s Post Hoc for multiple comparisons test were used for statistical analysis.
Results: The control group results revealed more significant stresses on the ridge with RPA and RPI clasps but on the abutment with WW clasp as P < 0.05. In group I, the ridge was significantly stressed more than the implant followed by the abutment when the RPA clasp was used while there was insignificance on the implant with RPA and RPI as p > 0.05. In group II, the stresses were more on the abutment with RPA, RPI, and WW clasps followed by lower on the implant and lowest on the ridge.
Conclusions: Proper implant and clasp type selection are critical for stress distribution on the ridge, abutment, and implant when using removable partial overdenture. The stresses on longer implants are tolerated and more widely distributed than shorter ones.
Keywords: implant dimension; mandibular overdenture; stress distribution.
© 2024 by the American College of Prosthodontists.
Egyptian dental journal, 2021
Purpose: To investigate and compare the influences of adding different concentrations of colloida... more Purpose: To investigate and compare the influences of adding different concentrations of colloidal forms silver nanoparticles on color changes of heat cured acrylic resin denture base material submitted to Accelerated aging. Methods: A total of 40 disc-shaped specimens were prepared from heat cured PMMA resins with different concentration of silver nanoparticles. The specimens were divided into 4 groups according to the addition of colloidal form of silver nanoparticles (NAg) percentage (1%, 2% and 5% vol.) which added to the liquid of resin (n = 10); Group I heat cured control group without additives and Groups (II, III and IV) with (1%, 2% and 5%) additives, respectively. All test group specimens were initially measured for color alteration and after each period of accelerated aging stages 252 H (stage I), 504H (stage II), and 1008 H (stage III). A double beam ultraviolet visible spectrophotometer was used to obtain diffuse reflectance data at every 5nm between 400-700nm. The results were recorded using a computer color matching system (CCM) and tabulated for the statistical analysis of the color differences (ΔE) data. Comparisons between the different studied groups were analyzed using F-test (ANOVA) and Post Hoc test (Scheffe) for pair-wise comparisons. Significance of the obtained results was judged at the significance level of α = 0.05. Results: All groups of heat-cured acrylic resin with the addition of (NAg) groups II, III and IV were showed significant (ΔE) values more than group I at initial and at stage I, II of accelerated aging records. In stage III only group IV was showed significant (ΔE) values more than group I of the same stage. Therefore, group IV was showed significantly highest mean (ΔE) value followed by group III then group II (P < 0.05) in all accelerated aging stages but group I was showed significantly lowest mean (ΔE). Conclusion: The silver nanoparticles incorporation within the acrylic denture base material can change its color. The higher incorporation of silver nanoparticles with accelerated aging, the more color difference values (ΔE) of the acrylic resin denture.
International Journal of Dentistry, 2015
Objective. To investigate the influence of reproduction of different thickness and palatal rugae ... more Objective. To investigate the influence of reproduction of different thickness and palatal rugae materials on complete dentures speech using Computerized Speech Lab (CSL) (spectrogram). Materials and Methods. Three completely edentulous male patients (aged 50-60 years) were selected for reading a paragraph. Twelve upper dentures were constructed, four for each patient. The patients&#39; speech groups were divided into five groups, Group I: patients without dentures; Group II: patients rehabilitated with conventional acrylic dentures; Group III: patients with conventional acrylic dentures with rugae reproduction; Group IV: patients with dentures with metallic framework of minimal thickness and direct ragged metallic palatal surface at rugae area; Group V: patients with dentures with palatal rugae constructed from resilient acrylic resin material with thickness less than conventional denture. Speech samples were recorded after insertion of each denture for groups using Computerized Speech Lab (CSL) (spectrogram). The sounds selected were lingopalatal /s/z/sh/t/d/ and /l/. Results. Group III produced high mean significant difference with /sh/t/ sound. For Group IV, the difference was noticed with /s/z/sh/t/ and /d/ sounds, while for Group V the difference was shown with /z/l/ sound (P &lt; 0.05). Conclusion. It is recommended to reproduce the rugae area in complete denture because the phonetic quality of complete denture with rugae is superior to the conventional denture.
Egyptian dental journal, Apr 1, 2016
Purpose: The purpose of this study was to investigate the effect of tissue conditioner leached ou... more Purpose: The purpose of this study was to investigate the effect of tissue conditioner leached out solvent contents on the surface roughness of heat-polymerized acrylic and visible light activated denture base materials. Methods: A total of 40 square-shaped specimens (10 x10 x2 mm) were constructed from heatpolymerized acrylic (Ecocryl) (Group A) and visible light cured (Eclipse) resins (Group B); each of which 20). The specimens were further divided into four subgroups (n= 10); Group AІ: Heat cured acrylic resin control group. Group AII: Heat cured acrylic resin specimens lined with tissue conditioner material. Group BI: Light cured resin control group. Group BII: Light cured resin specimens lined with tissue conditioner material. The initial (IRa) and final (FRa) surface roughness measurements were performed by using MarSurfPS1 profilometer after and before application of tissue conditioner on the specimens. The data was collected and statistically analyzed using paired sample t-test and independent t-test at the significance level of (α = 0.05). Results: There were a significant difference in surface roughness between group AI and AII (p&lt;0.05). A significance difference was also found between group BI and BII (p&lt;0.05). However, there was no significant difference between group AII and BII (p&gt;0.05). Conclusions: The polished surface of the denture base material has changed with the using of tissue conditioner. The heat cured acrylic resin which used as denture base material was more resistant to solvent contents of tissue conditioner than visible light cured resin. Keywords: Tissue conditioner, Surface roughness, Profilometer, Acrylic resin.
European Journal of Dentistry, Apr 1, 2017
The ADA has been registered various chemical disinfectants such as glutaraldehyde, chlorine compo... more The ADA has been registered various chemical disinfectants such as glutaraldehyde, chlorine compounds, iodophors, and phenols for immersion INTRODUCTION Dental impressions are often contaminated with microorganisms even washing them under tap water does not always guarantee that all organisms have been removed. The Center for Disease Control and the American Dental Association (ADA) have recommended disinfection of impression immediately after removal from the mouth. This prevents cross-contamination of infectious diseases such as hepatitis B, tuberculosis, herpes,
Egyptian dental journal, 2023
Aim of this study was to evaluate influence of thermoplastic denture base material on plaque inde... more Aim of this study was to evaluate influence of thermoplastic denture base material on plaque index and depth of gingival sulcus of implants supported mandibular overdenture. Patients and methods: Twenty completely edentulous patients were selected according to inclusion and exclusion criteria that affect implant success. Two implants were implanted in the interforaminal area of mandible following the two stages surgical protocol; patients were grouped into two groups Group I (TPG) patients received a complete mandibular overdenture constructed of thermoplastic poly amide denture base material and Group II (HCG) patients received a complete mandibular overdenture constructed of conventional heat cured acrylic resin, both groups are retained by ball and socket attachment system. Plaque index and depth of gingival sulcus were measured for each group after overdenture construction and every three months interval for 24 months. One-way ANOVA with post hoc turkey test was used for multiple time comparison. Results: the mean value of pocket depth between 2 groups [TPG-HCG] at different period has no statistically significant difference but statistically significant at a period of twenty four month <0.001 * P-value. plaque index show statistically significant <0.001 * P-value at all different periods. Conclusion: thermoplastic denture base overdenture has a superior benefit than conventional heat cured type as it give longevity of supported implant by enhancing peri-implant gingival health with reduced pocket depth and plaque index.
Journal of Clinical and Diagnostic Research, 2018
Introduction: Surface Porosities and solubility are undesirable characteristics of PMMA that sign... more Introduction: Surface Porosities and solubility are undesirable characteristics of PMMA that significantly weaken a denture base and promote staining, harboring of organisms such as Candida Albicans and bond failures between the artificial tooth and denture base resin. Aim: To evaluate and compare porosities and solubility between thermoplastic flexible and conventional heat cured acrylic resin denture base material. Materials and Methods: A total of 40 disc samples of thermoplastic and heat cured resin were prepared and divided into 2 groups: group I flexible polyamide resin and group II heat cured resin and then they were further distributed for solubility and porosity testing. Solubility was measured by registering the desorption of the samples that gained water after four weeks then weighed weekly till six weeks. The porosity was estimated quantitatively by total pore volume (W0). An electronic analytical balance was used to weight the samples. The data was collected and statistically analysed using ANOVA test. A paired sample t-test and independent t-test at the significance level of (α = 0.05) were used for comparison between two groups. Results: The change in solubility over time for flexible and conventional group was statistically non-significant. In comparison between flexible vs. conventional solubility; it was noted statistically non-significant at all storage time. The change in porosity with time for flexible and conventional group was statistically significant. Conclusion: More porosity of the flexible (thermoplastic polyamide nylon) resin would eventually promote hygiene maintenance. Flexible denture bases may be indicated in patient&#39;s requiring replacement of teeth in aesthetic zone, severe soft and hard tissue undercuts, allergy to acrylic or metal.
In the past the maxillofacial defects are difficult to treat and management. Maxillofacial prosth... more In the past the maxillofacial defects are difficult to treat and management. Maxillofacial prosthesis is one of the most important branch in prosthodontics. Now there are different treatment modalities and the management also advanced with applications of new materials. The patient with defect in maxillofacial region suffering from a major problem with his or her self and with the society but with the proper treatment of the defect and proper material selection the problem can be minimized. There are a missed ideas about this field specially for graduated and post-graduated dentist so, this book come to discuss in simple form the prosthetic management of Maxillofacial patients.
Egyptian dental journal, 2023
Aim of this study was to evaluate influence of thermoplastic denture base material on plaque inde... more Aim of this study was to evaluate influence of thermoplastic denture base material on plaque index and depth of gingival sulcus of implants supported mandibular overdenture. Patients and methods: Twenty completely edentulous patients were selected according to inclusion and exclusion criteria that affect implant success. Two implants were implanted in the interforaminal area of mandible following the two stages surgical protocol; patients were grouped into two groups Group I (TPG) patients received a complete mandibular overdenture constructed of thermoplastic poly amide denture base material and Group II (HCG) patients received a complete mandibular overdenture constructed of conventional heat cured acrylic resin, both groups are retained by ball and socket attachment system. Plaque index and depth of gingival sulcus were measured for each group after overdenture construction and every three months interval for 24 months. One-way ANOVA with post hoc turkey test was used for multiple time comparison. Results: the mean value of pocket depth between 2 groups [TPG-HCG] at different period has no statistically significant difference but statistically significant at a period of twenty four month &lt;0.001 * P-value. plaque index show statistically significant &lt;0.001 * P-value at all different periods. Conclusion: thermoplastic denture base overdenture has a superior benefit than conventional heat cured type as it give longevity of supported implant by enhancing peri-implant gingival health with reduced pocket depth and plaque index.
Hamada Atia, 2023
Aim of this study was to evaluate influence of thermoplastic denture base material on plaque inde... more Aim of this study was to evaluate influence of thermoplastic denture base material on plaque index and depth of gingival sulcus of implants supported mandibular overdenture. Patients and methods: Twenty completely edentulous patients were selected according to inclusion and exclusion criteria that affect implant success. Two implants were implanted in the interforaminal area of mandible following the two stages surgical protocol; patients were grouped into two groups Group I (TPG) patients received a complete mandibular overdenture constructed of thermoplastic poly amide denture base material and Group II (HCG) patients received a complete mandibular overdenture constructed of conventional heat cured acrylic resin, both groups are retained by ball and socket attachment system. Plaque index and depth of gingival sulcus were measured for each group after overdenture construction and every three months interval for 24 months. One-way ANOVA with post hoc turkey test was used for multiple time comparison. Results: the mean value of pocket depth between 2 groups [TPG-HCG] at different period has no statistically significant difference but statistically significant at a period of twenty four month <0.001 * P-value. plaque index show statistically significant <0.001 * P-value at all different periods. Conclusion: thermoplastic denture base overdenture has a superior benefit than conventional heat cured type as it give longevity of supported implant by enhancing peri-implant gingival health with reduced pocket depth and plaque index.
Egyptian Dental Journal, 2021
Purpose: To investigate and compare the influences of adding different concentrations of colloida... more Purpose: To investigate and compare the influences of adding different concentrations of colloidal forms silver nanoparticles on color changes of heat cured acrylic resin denture base material submitted to Accelerated aging. Methods: A total of 40 disc-shaped specimens were prepared from heat cured PMMA resins with different concentration of silver nanoparticles. The specimens were divided into 4 groups according to the addition of colloidal form of silver nanoparticles (NAg) percentage (1%, 2% and 5% vol.) which added to the liquid of resin (n = 10); Group I heat cured control group without additives and Groups (II, III and IV) with (1%, 2% and 5%) additives, respectively. All test group specimens were initially measured for color alteration and after each period of accelerated aging stages 252 H (stage I), 504H (stage II), and 1008 H (stage III). A double beam ultraviolet visible spectrophotometer was used to obtain diffuse reflectance data at every 5nm between 400-700nm. The results were recorded using a computer color matching system (CCM) and tabulated for the statistical analysis of the color differences (ΔE) data. Comparisons between the different studied groups were analyzed using F-test (ANOVA) and Post Hoc test (Scheffe) for pair-wise comparisons. Significance of the obtained results was judged at the significance level of α = 0.05. Results: All groups of heat-cured acrylic resin with the addition of (NAg) groups II, III and IV were showed significant (ΔE) values more than group I at initial and at stage I, II of accelerated aging records. In stage III only group IV was showed significant (ΔE) values more than group I of the same stage. Therefore, group IV was showed significantly highest mean (ΔE) value followed by group III then group II (P < 0.05) in all accelerated aging stages but group I was showed significantly lowest mean (ΔE). Conclusion: The silver nanoparticles incorporation within the acrylic denture base material can change its color. The higher incorporation of silver nanoparticles with accelerated aging, the more color difference values (ΔE) of the acrylic resin denture.
European Journal of Dentistry, 2015
Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporat... more Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 × 10 × 2 mm) of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT. Results: The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent Tan δ values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically significant differences in storage modulus E’, lost modulus E” or los...
Journal of Clinical and Diagnostic Research, 2018
Introduction: Surface Porosities and solubility are undesirable characteristics of PMMA that sign... more Introduction: Surface Porosities and solubility are undesirable characteristics of PMMA that significantly weaken a denture base and promote staining, harboring of organisms such as Candida Albicans and bond failures between the artificial tooth and denture base resin. Aim: To evaluate and compare porosities and solubility between thermoplastic flexible and conventional heat cured acrylic resin denture base material. Materials and Methods: A total of 40 disc samples of thermoplastic and heat cured resin were prepared and divided into 2 groups: group I flexible polyamide resin and group II heat cured resin and then they were further distributed for solubility and porosity testing. Solubility was measured by registering the desorption of the samples that gained water after four weeks then weighed weekly till six weeks. The porosity was estimated quantitatively by total pore volume (W0). An electronic analytical balance was used to weight the samples. The data was collected and statistically analysed using ANOVA test. A paired sample t-test and independent t-test at the significance level of (α = 0.05) were used for comparison between two groups. Results: The change in solubility over time for flexible and conventional group was statistically non-significant. In comparison between flexible vs. conventional solubility; it was noted statistically non-significant at all storage time. The change in porosity with time for flexible and conventional group was statistically significant. Conclusion: More porosity of the flexible (thermoplastic polyamide nylon) resin would eventually promote hygiene maintenance. Flexible denture bases may be indicated in patient's requiring replacement of teeth in aesthetic zone, severe soft and hard tissue undercuts, allergy to acrylic or metal.
Objectives: To evaluate the retention and wear behavior for different designs of precision attach... more Objectives: To evaluate the retention and wear behavior for different designs of precision attachments. Materials and Methods: Fifteen specimens of OT attachments castable system (Rhein83) with three different designs with plastic female parts and metal alloy male parts were selected. The specimens divided into three different designs groups; group I containing OT cap attachments, group II containing OT vertical attachments and group III containing OT strategy attachments. Each specimen subjected to 1200 wear cycle in a universal testing machine. Each cycle had performed full insertion/separation movement in an axial direction at a cross head speed of 50 mm/min in the presence of artificial saliva; and the retentive force had been measured at different thirteen intervals. Before and after testing, each one of the polymeric retentive female parts (caps and clips) had been individually weighted and scanned by SEM using low vacuum mode to detect loss of material and worn areas. Results: One-way ANOVA test revealed that there was a statistically significant difference between the groups (P<0.001). Pair-wise comparisons between the groups showed that; group II (OT vertical) showed the highest mean weight and retention loss followed by group I (OT cap) then group III (OT strategy). All designs subjected to wear but only OT vertical (group II) attachments have showed marked wear and retention loss. Conclusion: The designs of attachments have an important role in wear process. OT cap attachments and OT strategy attachments showed slight wear and material loss in comparison to OT vertical attachments.
EGYPTIAN DENTAL JOURNAL, 2016
Purpose: The purpose of this study was to investigate the effect of tissue conditioner leached
ou... more Purpose: The purpose of this study was to investigate the effect of tissue conditioner leached
out solvent contents on the surface roughness of heat-polymerized acrylic and visible light activated
denture base materials.
Methods: A total of 40 square-shaped specimens (10 x10 x2 mm) were constructed from heatpolymerized
acrylic (Ecocryl) (Group A) and visible light cured (Eclipse) resins (Group B); each
of which 20). The specimens were further divided into four subgroups (n= 10); Group AІ: Heat
cured acrylic resin control group. Group AII: Heat cured acrylic resin specimens lined with tissue
conditioner material. Group BI: Light cured resin control group. Group BII: Light cured resin
specimens lined with tissue conditioner material. The initial (IRa) and final (FRa) surface roughness
measurements were performed by using MarSurfPS1 profilometer after and before application of
tissue conditioner on the specimens. The data was collected and statistically analyzed using paired
sample t-test and independent t-test at the significance level of (α = 0.05).
Results: There were a significant difference in surface roughness between group AI and AII
(p<0.05). A significance difference was also found between group BI and BII (p<0.05). However,
there was no significant difference between group AII and BII (p>0.05).
Conclusions: The polished surface of the denture base material has changed with the using
of tissue conditioner. The heat cured acrylic resin which used as denture base material was more
resistant to solvent contents of tissue conditioner than visible light cured resin.
Keywords: Tissue conditioner, Surface roughness, Profilometer, Acrylic resin.
Objective: The aim of this study was to investigate the effect of adding different concentrations... more Objective: The aim of this study was to investigate the effect of adding different concentrations nanoparticles of silver on color stability of acrylic resin denture base material. Materials and Methods: A total of 20 discs were used in this study, divided into 4 groups (5 each) relative to percentage of nanoparticles of silver (NAg) adding (1%, 2%and 5%) and one group without additives (control group). A double beam ultraviolet visible spectrophotometer was used to obtain diffuse reflectance data at every 5nm between 400-700nm. An integrating sphere attachment was used for the measurement. The results were recorded using a computer color matching system (CCM) and tabulated for the statistical analysis of the data. Data analysis was performed by one way ANOVA. Post Hoc test (Scheffe) was used for pair-wise comparison between the means when ANOVA test is significant. Results: Heat-cured acrylic resin with 5% nanoparticles of silver (group D) showed significantly highest mean color differences (ΔE) followed by heat-cured acrylic resin with 2% nanoparticles of silver (group C) then heat-cured acrylic resin with 1% nanoparticles of silver (group B). Heat-cured acrylic resin without additives (control group) showed significantly lowest mean color differences (ΔE). The results of color differences (ΔE) showed significant difference (P<0.05) between groups (B, C and D) and group A. Conclusion: All Groups of heat-cured acrylic resin with addition of nanoparticles of silver (NAg) showed color differences (ΔE) values higher than that control group. From a clinical point of view, the silver nanoparticles incorporation within the acrylic denture base material can be improve its color stability. (Jul 2013)
Journal of clinical and diagnostic research : JCDR, 2015
Surface roughness is an important property of denture bases since denture bases are in contact wi... more Surface roughness is an important property of denture bases since denture bases are in contact with oral tissues and a rough surface may affect tissues health due to microorganism accumulation. Therefore, the effect of cigarette smoke on the surface roughness of two commercially available denture base materials was evaluated to emphasize which type has superior properties for clinical use. A total numbers of 40 specimens were constructed from two commercially available denture base materials; heat-cured PMMA and visible light cured UDMA resins (20 for each). The specimens for each type were randomly divided into: Group I: Heat cured resin control group; Group II: Heat cured acrylic resin specimens exposed to cigarette smoking; Group III: Light cured resin control group; Group IV: Light cured resin specimens exposed to cigarette smoking. The control groups used for immersion in distilled water and the smoke test groups used for exposure to cigarette smoking. The smoke test groups spe...
Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporat... more Objective: The objective was to investigate the effect of silver nanoparticles (AgNPs) incorporation on viscoelastic
properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 × 10 × 2 mm)
of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration
of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without
additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized
material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT.
Results: The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent
Tan δ values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically
significant differences in storage modulus E’, lost modulus E” or loss tangent Tan δ with other groups (P > 0.05).
Conclusion: The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties.
Key words: Acrylic resin denture, nanoparticles, viscoelastic
Objective.To investigate the influence of reproduction of different thickness and palatal rugaema... more Objective.To investigate the influence of reproduction of different thickness and palatal rugaematerials on complete dentures speech
usingComputerized Speech Lab (CSL) (spectrogram).Materials and Methods.Three completely edentulousmale patients (aged 50–
60 years) were selected for reading a paragraph. Twelve upper dentures were constructed, four for each patient. Thepatients’ speech
groups were divided into five groups, Group I: patients without dentures; Group II: patients rehabilitated with conventional acrylic
dentures; Group III: patients with conventional acrylic dentures with rugae reproduction; Group IV: patients with dentures with
metallic framework of minimal thickness and direct ragged metallic palatal surface at rugae area; Group V: patients with dentures
with palatal rugae constructed from resilient acrylic resin material with thickness less than conventional denture. Speech samples
were recorded after insertion of each denture for groups using Computerized Speech Lab (CSL) (spectrogram).The sounds selected
were lingopalatal /s/z/sh/t/d/ and /l/. Results. Group III produced highmean significant difference with /sh/t/ sound. For Group IV,
the difference was noticed with /s/z/sh/t/ and /d/ sounds, while for Group V the difference was shown with /z/l/ sound (𝑃 < 0.05).
Conclusion. It is recommended to reproduce the rugae area in complete denture because the phonetic quality of complete denture
with rugae is superior to the conventional denture.
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Papers by Dr Hamada Z Mahross
Purpose: To analyze the distribution of stresses for mandibular Kennedy class I removable partial overdentures submitted to different implant lengths and clasp designs.
Materials and methods: Twenty-seven heat-cured acrylic resin casts with a uniform soft acrylic layer were constructed from models representing the mandibular Kennedy class I removable partial denture with the first premolars terminal abutment on both sides. The casts were grouped into a control group, group I, and group II with three casts of each for designing a different clasp on the last abutment with Rest, Proximal plate, Aker circumferential (RPA), Rest, Proximal plate, I-bar (RPI), and wrought wire (WW). All casts were submitted to vertical load for stress analysis after preparing channels at the buccal/distal surface of abutments, the crest of the ridge, and the buccal/lingual of the implant for placement of uniaxial strain gauges that can convert the electro-signals to micro-strain by using the software. Kolmogorov-Smirnov normality test, independent t-test, and one-way anlysis of Variance (ANOVA) test followed by Tukey`s Post Hoc for multiple comparisons test were used for statistical analysis.
Results: The control group results revealed more significant stresses on the ridge with RPA and RPI clasps but on the abutment with WW clasp as P < 0.05. In group I, the ridge was significantly stressed more than the implant followed by the abutment when the RPA clasp was used while there was insignificance on the implant with RPA and RPI as p > 0.05. In group II, the stresses were more on the abutment with RPA, RPI, and WW clasps followed by lower on the implant and lowest on the ridge.
Conclusions: Proper implant and clasp type selection are critical for stress distribution on the ridge, abutment, and implant when using removable partial overdenture. The stresses on longer implants are tolerated and more widely distributed than shorter ones.
Keywords: implant dimension; mandibular overdenture; stress distribution.
© 2024 by the American College of Prosthodontists.
out solvent contents on the surface roughness of heat-polymerized acrylic and visible light activated
denture base materials.
Methods: A total of 40 square-shaped specimens (10 x10 x2 mm) were constructed from heatpolymerized
acrylic (Ecocryl) (Group A) and visible light cured (Eclipse) resins (Group B); each
of which 20). The specimens were further divided into four subgroups (n= 10); Group AІ: Heat
cured acrylic resin control group. Group AII: Heat cured acrylic resin specimens lined with tissue
conditioner material. Group BI: Light cured resin control group. Group BII: Light cured resin
specimens lined with tissue conditioner material. The initial (IRa) and final (FRa) surface roughness
measurements were performed by using MarSurfPS1 profilometer after and before application of
tissue conditioner on the specimens. The data was collected and statistically analyzed using paired
sample t-test and independent t-test at the significance level of (α = 0.05).
Results: There were a significant difference in surface roughness between group AI and AII
(p<0.05). A significance difference was also found between group BI and BII (p<0.05). However,
there was no significant difference between group AII and BII (p>0.05).
Conclusions: The polished surface of the denture base material has changed with the using
of tissue conditioner. The heat cured acrylic resin which used as denture base material was more
resistant to solvent contents of tissue conditioner than visible light cured resin.
Keywords: Tissue conditioner, Surface roughness, Profilometer, Acrylic resin.
properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 × 10 × 2 mm)
of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration
of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without
additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized
material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT.
Results: The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent
Tan δ values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically
significant differences in storage modulus E’, lost modulus E” or loss tangent Tan δ with other groups (P > 0.05).
Conclusion: The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties.
Key words: Acrylic resin denture, nanoparticles, viscoelastic
usingComputerized Speech Lab (CSL) (spectrogram).Materials and Methods.Three completely edentulousmale patients (aged 50–
60 years) were selected for reading a paragraph. Twelve upper dentures were constructed, four for each patient. Thepatients’ speech
groups were divided into five groups, Group I: patients without dentures; Group II: patients rehabilitated with conventional acrylic
dentures; Group III: patients with conventional acrylic dentures with rugae reproduction; Group IV: patients with dentures with
metallic framework of minimal thickness and direct ragged metallic palatal surface at rugae area; Group V: patients with dentures
with palatal rugae constructed from resilient acrylic resin material with thickness less than conventional denture. Speech samples
were recorded after insertion of each denture for groups using Computerized Speech Lab (CSL) (spectrogram).The sounds selected
were lingopalatal /s/z/sh/t/d/ and /l/. Results. Group III produced highmean significant difference with /sh/t/ sound. For Group IV,
the difference was noticed with /s/z/sh/t/ and /d/ sounds, while for Group V the difference was shown with /z/l/ sound (𝑃 < 0.05).
Conclusion. It is recommended to reproduce the rugae area in complete denture because the phonetic quality of complete denture
with rugae is superior to the conventional denture.
Purpose: To analyze the distribution of stresses for mandibular Kennedy class I removable partial overdentures submitted to different implant lengths and clasp designs.
Materials and methods: Twenty-seven heat-cured acrylic resin casts with a uniform soft acrylic layer were constructed from models representing the mandibular Kennedy class I removable partial denture with the first premolars terminal abutment on both sides. The casts were grouped into a control group, group I, and group II with three casts of each for designing a different clasp on the last abutment with Rest, Proximal plate, Aker circumferential (RPA), Rest, Proximal plate, I-bar (RPI), and wrought wire (WW). All casts were submitted to vertical load for stress analysis after preparing channels at the buccal/distal surface of abutments, the crest of the ridge, and the buccal/lingual of the implant for placement of uniaxial strain gauges that can convert the electro-signals to micro-strain by using the software. Kolmogorov-Smirnov normality test, independent t-test, and one-way anlysis of Variance (ANOVA) test followed by Tukey`s Post Hoc for multiple comparisons test were used for statistical analysis.
Results: The control group results revealed more significant stresses on the ridge with RPA and RPI clasps but on the abutment with WW clasp as P < 0.05. In group I, the ridge was significantly stressed more than the implant followed by the abutment when the RPA clasp was used while there was insignificance on the implant with RPA and RPI as p > 0.05. In group II, the stresses were more on the abutment with RPA, RPI, and WW clasps followed by lower on the implant and lowest on the ridge.
Conclusions: Proper implant and clasp type selection are critical for stress distribution on the ridge, abutment, and implant when using removable partial overdenture. The stresses on longer implants are tolerated and more widely distributed than shorter ones.
Keywords: implant dimension; mandibular overdenture; stress distribution.
© 2024 by the American College of Prosthodontists.
out solvent contents on the surface roughness of heat-polymerized acrylic and visible light activated
denture base materials.
Methods: A total of 40 square-shaped specimens (10 x10 x2 mm) were constructed from heatpolymerized
acrylic (Ecocryl) (Group A) and visible light cured (Eclipse) resins (Group B); each
of which 20). The specimens were further divided into four subgroups (n= 10); Group AІ: Heat
cured acrylic resin control group. Group AII: Heat cured acrylic resin specimens lined with tissue
conditioner material. Group BI: Light cured resin control group. Group BII: Light cured resin
specimens lined with tissue conditioner material. The initial (IRa) and final (FRa) surface roughness
measurements were performed by using MarSurfPS1 profilometer after and before application of
tissue conditioner on the specimens. The data was collected and statistically analyzed using paired
sample t-test and independent t-test at the significance level of (α = 0.05).
Results: There were a significant difference in surface roughness between group AI and AII
(p<0.05). A significance difference was also found between group BI and BII (p<0.05). However,
there was no significant difference between group AII and BII (p>0.05).
Conclusions: The polished surface of the denture base material has changed with the using
of tissue conditioner. The heat cured acrylic resin which used as denture base material was more
resistant to solvent contents of tissue conditioner than visible light cured resin.
Keywords: Tissue conditioner, Surface roughness, Profilometer, Acrylic resin.
properties of acrylic resin denture base material. Materials and Methods: A total of 20 specimens (60 × 10 × 2 mm)
of heat cured acrylic resin were constructed and divided into four groups (five for each), according to the concentration
of AgNPs (1%, 2%, and 5% vol.) which incorporated into the liquid of acrylic resin material and one group without
additives (control group). The dynamic viscoelastic test for the test specimens was performed using the computerized
material testing system. The resulting deflection curves were analyzed by material testing software NEXYGEN MT.
Results: The 5% nanoparticles of silver (NAg) had significantly highest mean storage modulus E’ and loss tangent
Tan δ values followed by 2% NAg (P < 0.05). For 1% nanosilver incorporation (group B), there were no statistically
significant differences in storage modulus E’, lost modulus E” or loss tangent Tan δ with other groups (P > 0.05).
Conclusion: The AgNPs incorporation within the acrylic denture base material can improve its viscoelastic properties.
Key words: Acrylic resin denture, nanoparticles, viscoelastic
usingComputerized Speech Lab (CSL) (spectrogram).Materials and Methods.Three completely edentulousmale patients (aged 50–
60 years) were selected for reading a paragraph. Twelve upper dentures were constructed, four for each patient. Thepatients’ speech
groups were divided into five groups, Group I: patients without dentures; Group II: patients rehabilitated with conventional acrylic
dentures; Group III: patients with conventional acrylic dentures with rugae reproduction; Group IV: patients with dentures with
metallic framework of minimal thickness and direct ragged metallic palatal surface at rugae area; Group V: patients with dentures
with palatal rugae constructed from resilient acrylic resin material with thickness less than conventional denture. Speech samples
were recorded after insertion of each denture for groups using Computerized Speech Lab (CSL) (spectrogram).The sounds selected
were lingopalatal /s/z/sh/t/d/ and /l/. Results. Group III produced highmean significant difference with /sh/t/ sound. For Group IV,
the difference was noticed with /s/z/sh/t/ and /d/ sounds, while for Group V the difference was shown with /z/l/ sound (𝑃 < 0.05).
Conclusion. It is recommended to reproduce the rugae area in complete denture because the phonetic quality of complete denture
with rugae is superior to the conventional denture.