Abstract Micro-hardness is a fundamental property of prosthodontic restorative materials, as it affects their resistance to surface deformation, wear, and long-term clinical performance. This study aimed to compare the Vickers micro-hardness of three widely used CAD/CAM materials: lithium disilicate, monolithic zirconia, and multilayered zirconia. A total of 30 specimens (N = 30) were fabricated, with 10 samples allocated to each material group. Lithium disilicate specimens were prepared as rectangular plates (18 × 15 × 1 mm), whereas zirconia specimens—both monolithic and multilayered—were fabricated as discs (10 mm in diameter and 1.5 mm in thickness) following standardized CAD/CAM milling and sintering protocols. Vickers micro-hardness testing was conducted using a digital micro-hardness tester under material-specific conditions: a load of 1 kg and a dwell time of 10 s for lithium disilicate, and a load of 500 g with a 20 s dwell time for zirconia. Statistical analysis was performed using one-way ANOVA followed by Tukey’s post-hoc test, with the significance level set at p < 0.05. Significant differences in micro-hardness were identified among the three materials (p < 0.001). Monolithic zirconia demonstrated the highest mean hardness (680 ± 19 HV), followed by multilayered zirconia (623 ± 47 HV), while lithium disilicate exhibited the lowest values (553 ± 32 HV). Post-hoc analysis confirmed that all pairwise comparisons were statistically significant. The findings indicate that monolithic zirconia possesses superior micro-hardness compared to multilayered zirconia and lithium disilicate, supporting its suitability for high-stress clinical applications. Multilayered zirconia offers a balance between mechanical performance and esthetics, whereas lithium disilicate remains optimal for highly esthetic anterior restorations. These results provide clinicians with evidence-based guidance for selecting CAD/CAM materials in fixed prosthodontic rehabilitation. 

The surface integrity of CAD/CAM restorative materials is critical for their esthetic and mechanical performance. Acidic challenges in the oral environment can degrade ceramic surfaces, increasing roughness and potentially compromising restoration longevity. This study aimed to evaluate and compare the effect of 4% acetic acid immersion on the surface roughness (Ra) of lithium disilicate glass-ceramic and hybrid ceramic (Vita Enamic) CAD/CAM restorative materials. A total of 40 rectangular specimens (18×15×1 mm) were fabricated, 10 per material per condition. Specimens were polished according to manufacturer protocols and immersed in 4% acetic acid (v/v) at 80∘C for 16 hours, following ISO 6872 standards. Surface roughness was measured using a Roughness Tester (PCE-RT 2000). Data were analyzed using independent t-tests, and effect sizes were calculated (Cohen’s d). Both materials exhibited significant increases in surface roughness after acid exposure. Lithium disilicate showed Ra values increasing from 0.0676±0.0187 µm to 0.5129±0.0912 µm (p<0.001, d=4.79). The hybrid ceramic exhibited a larger increase, from 0.2063±0.0568 µm to 1.4409±0.4951 µm (p<0.001, d=2.48). The hybrid material was therefore more susceptible to acid-induced degradation than lithium disilicate. Immersion in 4% acetic acid significantly deteriorates the surface of both lithium disilicate and hybrid ceramic, with hybrid ceramic showing greater roughness changes. Lithium disilicate may be preferred for patients at high risk of acidic challenges. These findings emphasize the importance of material selection and surface management to optimize restoration longevity.

Fracture toughness is a critical mechanical property influencing the clinical durability of prosthodontic materials, especially those used in high-stress posterior regions. Differences in composition, microstructure, and fabrication technologies can significantly affect resistance to crack propagation. This experimental study evaluated the fracture toughness of three prosthodontic material groups (n = 10 each). Standardized samples were prepared and tested using the Vickers indentation technique under controlled laboratory conditions. Descriptive statistics were calculated for each group, and a one-way analysis of variance (ANOVA) was performed to determine significant differences among the groups. Post-hoc pairwise comparisons were conducted using Tukey’s Honest Significant Difference (HSD) test. Statistically significant differences in fracture toughness were observed among the three groups (p < 0.001). Group II demonstrated the highest mean fracture toughness (5.39 ± 0.34 MPa·m^1/2), followed by Group III (4.34 ± 0.36 MPa·m1/2). Group I recorded the lowest mean value (2.82 ± 0.56 MPa·m1/2). Tukey’s post-hoc analysis confirmed that all pairwise comparisons were significant (p < 0.001), indicating that each material group exhibited distinct mechanical performance profiles. The findings show that the fracture toughness of prosthodontic materials vary significantly depending on their composition and manufacturing technology. Materials in Group II outperformed the other groups, suggesting greater suitability for clinical situations where high resistance to fracture is required. Further studies incorporating additional mechanical tests and long-term clinical evaluation are recommended to validate these results under functional oral conditions. 

The aesthetic performance of zirconia restorations depends greatly on their optical properties, particularly translucency, which can be influenced by various chemical exposures in the oral environment. This in vitro study aimed to evaluate the effect of different immersion solutions on the translucency of two types of zirconia materials. A total of 30 zirconia specimens (n = 15 per group) were prepared: Group A comprised monolithic zirconia, while Group B consisted of multilayered yttria-stabilized zirconia. Each group was divided into three subgroups (n = 5) and immersed in one of three solutions: distilled water (DW), chlorhexidine (CHX), or 0% alcohol mouthwash. Translucency parameters (TP) were measured before and after immersion using a spectrophotometer based on the CIELab system. Statistical analysis was conducted using GraphPad Instat software with significance set at p < 0.05. The results revealed that immersion in CHX caused the most significant increase in TP change in both groups, with monolithic zirconia (Group A) showing the highest overall change. Two-way ANOVA indicated that the immersion solution had a statistically significant effect on translucency (p < 0.0001), while the type of zirconia showed no significant main effect (p = 0.0779). These findings suggest that translucency changes are more dependent on the immersion media than the zirconia composition itself. Clinicians should consider the long-term aesthetic implications of chemical exposure on zirconia restorations, especially when prescribing disinfectant mouthwashes. 

This study was conducted to evaluate the surface roughness, shore hardness, and dimensional accuracy of commercially obtainable Prosthodontic polymer impression material in terms of imbibition after immersion in two different media and without disinfection. This in vitro study was designed to investigate the surface properties of polymer impression materials before and after disinfection by immersion. Materials with different consistencies (alginate (irreversible hydrocolloid), condensation silicone (putty), and addition silicone (putty) impression materials) were investigated. The tested null hypothesis was the fact that there would be no significant differences in surface properties among these Prosthodontic polymer impression materials. Two disinfecting agents, Zeta 7 solution and ASEPTOPRINT, were used to assess the surface roughness, hardness, and dimensional accuracy of the impression material. The weights of the discs of the Prosthodontic polymer impression material samples were measured before and immediately after immersion to determine if there was a change in the properties of the material. study was conducted at the Advanced Medical Polymer Group in the Libyan Polymer Research Center to evaluate the surface properties of prosthodontic polymer impression materials. Data analysis included mean, standard deviation, and One-way ANOVA calculations. The study showed that the surface properties of dental polymer impression materials were affected by disinfection methods. Specifically, for alginate material, there were significant differences in surface properties between the control group (before immersion) and after immersion in zeta 7 solution and ASEPTOPRINT spray. However, for addition silicone (putty), there was a significant difference in surface properties between the control group and after immersion in zeta 7 solution, while immersion in spray did not show a significant difference. For condensation silicone (putty) material, there were significant differences in surface properties between the control group

The purpose of this in-vitro study was to compare the fracture toughness of monolithic zirconia and multilayered zirconia, two commonly used materials in prosthodontic restorations. Fracture toughness is a key mechanical property that determines a material’s resistance to crack propagation under stress, which is crucial for the longevity and performance of dental restorations. A total of 20 zirconia discs (10 monolithic and 10 multilayered) were fabricated using Computer-Aided Design and Computer-Aided Manufacturing (CAD/CAM) technology. The discs were subjected to loading and fracture toughness was measured using the indentation method with a Vickers micro-hardness tester. The fracture toughness values for monolithic zirconia (Group 1) were significantly higher than those for multilayered zirconia (Group 2), with mean values of 5.394 ± 0.378 MPa·m1/2and 4.358 ± 0.394 MPa·m1/2, respectively (p < 0.0001). These findings suggest that monolithic zirconia offers superior mechanical performance, making it a more suitable material for high-stress applications, while multilayered zirconia may be preferred for anterior restorations, where esthetics are prioritized. The study highlights the trade-off between mechanical strength and esthetic appeal in the selection of zirconia materials for dental restorations and provides valuable insights for optimizing material choice in clinical prosthodontics.

This study aimed to evaluate and compare the microhardness of monolithic zirconia and multilayered zirconia to investigate the influence of material composition and structural design on their mechanical properties. Cylindrical specimens were designed using AutoCAD software and fabricated from monolithic zirconia (Group A) and multilayered zirconia (Group B blocks via CAD/CAM milling systems. The specimens were sectioned into discs with a diameter of 10 mm and a thickness of 1.5 mm. Microhardness testing was performed on these discs using a standardized protocol. Statistical analysis was conducted using a student’s t-test (P < 0.05) with a sample size of 10 specimens per group to ensure 80% power and 95% confidence. Results revealed significant differences in microhardness between monolithic and multilayered zirconia. Monolithic zirconia exhibited superior hardness, attributable to its single-layered structure, which enhances its mechanical strength and wear resistance. In contrast, multilayered zirconia, while exhibiting lower microhardness, demonstrated esthetic advantages due to its gradient layering and maintained sufficient durability for clinical use. The findings underscore the impact of zirconia composition and structural design on mechanical properties, providing clinicians with valuable insights for material selection. While monolithic zirconia is ideal for high-load posterior restorations, multilayered zirconia offers an esthetic solution with adequate mechanical performance, making it suitable for anterior applications. 

The diverse array of restorative materials utilized in computer-aided design/computer-aided manufacturing (CAD/CAM) technology necessitates a comprehensive understanding of their aesthetic properties and color stability. This study aimed to evaluate the color stability of two different types of zirconia after immersion in Chlorhexidine and ANTIPLACA mouthwashes. We prepared 30 zirconia specimens (n = 15) as follows: Group 1 consisted of monolithic zirconia and group 2 consisted of KATANA™ YML Zirconia. Groups 1 and 2 were divided into three subgroups (n = 5). Each subgroup was immersed in one of the following three solutions: distilled water (control), CHX, or ANTIPLACA 0%Alcohol. We recorded the samples’ color values at baseline and after immersion according to the CIELab system by using a color spectrophotometer operated by an experienced operator. All data were collected and analyzed using Graph Pad Instat (Graph Pad, Inc.) software for windows. Irrespective of group totally it was found that immersion solutions significantly affected on mean values as revealed by two-way ANOVA test (p=<0.0001< 0.05) where (0% Alcohol > CHX ≥ DW). Mouthwashes staining had a marked effect on the color of the tested zirconia materials. The color change was material and staining solution-dependent, with Monolithic Zirconia showing the greatest color stability.

Oral health and dental care are essential components of overall health, encompassing the absence of conditions such as oral and facial pain, cancers of the mouth and throat, infections, ulcers, gum dis ease, tooth decay, and tooth loss. These conditions can significantly impair an individual’s ability to bite, chew, smile, and speak. Cigarette smoking poses a major public health concern due to its con tribution to the proliferation of pathogenic microbes, as well as its role in oral cancer, gingivitis, tooth discoloration, halitosis, and other adverse health outcome. This study aims to assess the preva lence of dental care practices, smoking habits, and dental caries among students of the College of Engineering at El-Mergib University, located in Al-Khums. A self-administered questionnaire was distributed to a total of 250 students. Data were analyzed using Microsoft Excel, version 2010. The questionnaire was designed to evaluate participants' self-perception of dental care, oral health, oral hygiene practices, dental caries, bleeding gums, and smoking habits. The findings indicated a slightly higher prevalence of dental caries and smoking among participants who reported good oral hygiene practices, such as regular tooth cleaning and dental visits. The study advocates for the development of preventive health and oral hygiene programs to improve overall oral health. 

Surface properties of prosthodontic polymer impression materials, such as hardness, roughness, and accuracy, are crucial for the accurate replication of oral structures in restorative dentistry. To evaluate the surface properties by using different types of polymer impression materials commonly used in dentistry and analyze their surface characteristics. Materials and methods: Forty -five samples of materials were used, including alginate (irreversible hydrocolloid), condensation silicone (putty) and addition silicone (putty), study was conducted at the advanced medical polymer group in the Libyan Polymer Research Center to evaluate the surface properties of prosthodontic polymer impression materials. Three evaluation methods were used: Shore hardness testing, surface roughness testing, and dimensional accuracy measurements. Data analysis included mean, standard deviation, and One-way ANOVA calculations. Alginate has a lower hardness compared to addition silicone (putty) and condensation silicone (putty). The ANOVA test for surface roughness showed no significant differences among the materials, with a p-value of 0.027. For shore hardness, there were no significant differences among the materials, with a p-value of 0.000. The ANOVA test for dimensional accuracy showed no significant differences among the different periods for alginate, condensation silicone (putty) and addition silicone (putty), with p-values of 0.000 respectively. The study concluded that alginate had the lowest hardness and roughness compared to condensation silicone (putty) and addition silicone (putty). There are no significant differences among the material surface properties (Shore hardness and surface roughness) but not in dimensional accuracy among the materials. This information provides valuable insights for dental professionals working with impression material.