Background The purpose of this study evaluates and compares the effect of surface roughness (Ra) and color stability on computer-aided design/computer-aided manufacturing (CAD/CAM) hybrid resin (Vita Enamic), feldspathic (Vitablocs® Mark II), and lithium disilicate Zirconia (Vita Suprinity) glazed or polished ceramics immersed in hot Arabic Qahwa and cold coffee. Methods A total of 96 standardized samples were prepared from CAD/CAM restorative materials. Half of the samples were polished as per the manufacturer’s instructions using a porcelain polishing kit, and the other half were glazed. Samples were distributed and immersed in hot Arabian Qahwa and cold coffee followed by thermocycling. Ra measurements and color changes were conducted before and after immersion. SEM images were captured from each type of glazed or polished ceramic. One-way ANOVA paired Student’s t-test, and Bonferroni test were conducted to detect significant difference between the groups. P > 0.05 was a significant level. Results Of all the tested samples, Ra increased without any significant difference; however, mean color changes (ΔE*) showed significant differences. An increase in Ra was noted for all the glazed and polished samples after immersion and thermocycling. However, differences were significant only in VM II. In addition, ΔE* was significant only in Vita Suprinity (VS) samples. For immersion groups, significant Ra changes were noticed in glazed samples, only in Vita Enamic (VE) with no ΔE*. In polished samples, mean Ra changes were observed in VM II and VS samples. Significant differences were also noticed in polished VE and VS subgroups of ΔE*. Conclusions Ra affects all the tested samples, providing higher values on the polished specimens. The ΔE* caused by hot Arabic Qahwa and cold coffee on glazed or polished CAD/CAM restorative materials were clinically acceptable.

Aim:The aim of the current study is to assess the influence of Coca-Cola drinks on the overall color of glazed or polished porcelain veneers fabricated of three different porcelain systems and two different thicknesses. Materials and methods: A total of 96 ceramic disk specimens were fabricated. The ceramic veneers were prepared to a standardized thickness of 1.0 mm ± 0.025 mm and 0.6 ± 0.025 (48 samples each group) using the following ceramic systems: Zircon, E-max press, and E-max CAD/CAM. Veneer samples from each system were divided into two subgroups (n = 8). First subgroup samples were glazed according to the manufacturer's instructions, and the other subgroup samples were adjusted with diamond burs then polished with ceramic polishing kit. Color was measured with Vita Easyshade spectrophotometer. Then all samples immersed with Cola drink, for 4 weeks, in a thermocycling machine and then the color were measured again and color change was recorded. Results: Significant differences in color change were noticed before and after immersing with Coca-Cola and thermocycling for all materials and thicknesses used (p < 0.01). Significant differences in color changes were noticed between glazed and polished samples (p < 0.001). No significant differences in color change were noticed when using different thicknesses for all materials used (p < 0.05). Conclusion: Different porcelain materials have shown significant color changes after immersing and thermocycling in Coca-Cola drinks. The color changes of polished porcelain specimens were more considerable than those of polished specimens for all porcelain materials and thicknesses used. This suggests reglazing of all esthetic restoration after any adjustments might be performed and before final cementation in an attempt to maintain the color stability in oral environment. Clinical significance: To achieve a perfect color stability of ceramic veneers, clinicians should take into consideration the possible color deviations that might result after any adjustment followed by polishing procedures to the ceramic surface. And, it is always preferable to do reglazing of porcelain restorations after any surface treatments and before final cementation.

Background and Objectives: Khat chewing is considered as a daily habit that is practiced by more than five million people globally. The effect of khat chewing on the surface roughness and the color stability of natural teeth and the material used in the fabrication of dental prosthesis remains unknown. This study was conducted to explore and compare the effect of khat homogenate (KH) on the surface roughness (Ra) and the average color changes (ΔE*) amongst natural teeth and selected shades from different porcelain types, namely, feldspathic metal ceramic (MC) VM13, computer-aided design/computer assisted manufacture (CAD/CAM) feldspathic (Vitablocs Mark II), and multilayer zirconia (Ceramill Zolid PS) porcelains. Materials and Methods: Seventy samples were prepared from natural teeth, feldspathic MC, CAD/CAM Vitablocs Mark II, and zirconia porcelain. The Ra values were measured using a profilometer and expressed in micrometers, whereas the ΔE* values were measured using VITA Easyshade® V spectrophotometer for all samples before and after frequent immersion and thermocycling in KH for 30 days. The surface topography was used to assess the materials surfaces (glazed or polished) after KH immersion by using a white light interferometry machine. Results: Results revealed that the Ra and the ΔE* values of the different types of tested porcelain were influenced by KH. The order of surface roughness values was glazed or polished MC > polished Zircon > polished Vitablocs Mark II > natural teeth. The lowest ΔE* values were recorded for glazed Vitablocs Mark II and MC, and the values could be arranged as polished zircon > natural teeth > glazed zircon > polished MC > polished Vitablocs Mark II. P values were significantly varied (<0.001) among all the tested groups, except the zircon group (>0.05) for both Ra and ΔE*. Conclusions: KH significantly affected both surface parameter and color of glazed or polished porcelain materials and natural teeth.

Background This spectrophotometric study assessed the color stability of CAD/CAM restorative materials with different exposed surfaces following staining by hot Arabic Qahwa and cold coffee. Material/Methods Ninety-six specimens were fabricated from 3 different CAD/CAM ceramic materials: Vita Suprinity (Vita-S), Vita Enamic (Vita-E), and Vitablocs Mark II (Vitablocs-MII). We divided 32 specimens for each group into glazed or polished surfaces, with 16 specimens in each group, then subdivided them according to staining materials: Arabic Qahwa and Frappuccino Cold Coffee. Color of specimens was measured during immersion in staining materials (BEFORE) as baseline with (Vita classic) and (L, a, b), for average color changes (ΔE 00 ), then remeasured after 2, 4, and 12 weeks, and described as 1 st , 2 nd , and 3 rd measurements for VITAPAN Classic shade and T1, T2, and T3 for ΔE 00 values using the CIE L*a*b* equation. We performed ANOVA and then post hoc testing. Results We found significant differences in ΔE 00 values during immersing in hot Arabic Qahwa and cold coffee for tested materials in glazed or polished specimens. Polished specimens of Vita-S and Vita-E had the highest color changing and staining compared to glazed surfaces. Vitablocs-MII had the best color stability through immersion periods. Moreover, there were changes in relation to VITAPAN Classic shade guide for both Vita-S and Vita-E specimens during different immersion periods. Conclusions Coffee caused staining and contamination of ceramic material. Values of ΔE 00 for tested ceramic materials were significantly different but were within the clinically acceptable range. Polished specimens showed higher staining; therefore, we highly recommend re-glazing of ceramic restorations to maintain color stability.

BACKGROUND: Digital complete dentures (CDs) by computer-aided designing and computer-aided manufacturing (CAD-CAM) techniques (milling and three-dimensional (3-D) printing) have been evaluated clinically and provided satisfactory results. But clinical studies assessing occlusal forces by digital dentures are lacking. OBJECTIVES: To compare the occlusal force parameters in complete dentures (CDs) fabricated by milling, 3-D printing and conventional techniques having 3 commonly used occlusal schemes, using computerized occlusal force analysis system (Tech-Scan III- T-Scan III). METHODS: A total of 45 CDs were fabricated for 5 patients. Nine sets of CDs were made for each patient and were divided into 3 groups: Conventional CDs (CCD), Milled CDs (MCD), and 3-D printed CDs (3-DP CD). The CDs in each group were further divided into 3 sub-groups based on occlusion schemes – bilateral balanced (BBO), lingualized (LO) and mono plane (MP). Occlusal force analysis [percentage (%) of occlusal force applied on the right and left sides of the arch difference between them, centralization of forces and % of maximum occlusal/bite force] was done using computerized occlusal analysis system (T-Scan III) at the time of denture insertion. Univariate regression analysis and logistic regression analysis were performed (p< 0.05). RESULTS: The intergroup comparison of force distribution on right and left side in CDs fabricated by various techniques showed insignificant differences (p> 0.05) but statistically significant differences (p< 0.01) were found in Right – Left side force difference, maximum bite force % and centralization of forces. The maximum force difference on right and left side was observed CCD with MO (37.48 ± 1.03 N) and maximum occlusal-bite force % was observed for 3-DPCD with LO (95.40 ± 1.30 N). In comparison to 3-DP CD, the chances of centre of force out of ellipse (centralization of forces) was 3.36 and 2.15 times more in CCD and MCD techniques made CDs respectively. CONCLUSIONS: The occlusal parameters in CDs were affected by the fabrication techniques and occlusal schemes of CDs. The digital CDs retain adjusted occlusal schemes better and 3-DP CDs with BBO and LO occlusal schemes provided centralization of forces, better distribution and high maximum occlusal force % respectively.

Background: The habit of khat (Catha Edulis Forskal) chewing is widely practiced in the southern regions of Saudi Arabia, Yemen, and East Africa. This social habit has tremendous effects on oral and general health of khat chewers. Khat may affect bacterial species in plaque biofilms on oral rehabilitation materials. This preliminary case-controlled study aimed to assess and compare the effect of khat chewing on bacterial biodiversity between nonkhat chewers (NKC) and khat chewers (KC) in oral biofilms on oral rehabilitation materials using polymerase chain reaction (PCR). Material/Methods: Fifty participants were organized into 2 equal groups of NKC and KC, each containing 5 subgroups related to filling material type. Some participants had amalgam (A) or composite (C) restorations, while others had feldspathic porcelain (FP), nickel chromium (NC), and zirconia ceramic (ZC) crowns or bridges. Oral biofilm samples were collected from all participants, DNA was extracted, and samples were subjected to PCR. Bacterial species were then identified and counted. PCR products were sequenced to detect similarity. Partial 16S rRNA gene sequences of the current study samples were compared with 16S rRNA gene sequences from GenBank using BLAST on the National Center for Biotechnology Information website. Results: The Streptococcus sp. was the most common bacterial species among our participants (40; 80%), followed by Lactobacillus and Veillonella spp., accounting for 12% (6) and 8% (4), respectively. Streptococcus sp. was observed equally among NKC and KC, but Lactobacillus and Veillonella spp. were higher in KC and NKC, respectively. Lactobacillus was associated mainly with prosthetic materials, and Streptococcus was found among all examined dental restorative materials. Conclusions: This research concluded that khat chewing significantly affects bacterial biodiversity in oral biofilms in the presence of different restorative and prosthetic dental materials.

BACKGROUND: Fabrication of complete dentures by computer-aided designing and computer-aided manufacturing (CAD-CAM) techniques are now common. Subtractive and Additive are the two principal CAD-CAM techniques used for this purpose. However, studies that evaluated the occlusal forces by CDs manufactured by these techniques are lacking. OBJECTIVES: To compare the occlusal forces in complete dentures fabricated by additive, subtractive and conventional techniques with different occlusal schemes, using computerized occlusal force analysis system [Tech-Scan III (T-scan III)]. METHODS: Three groups (Gr) were made on the basis of techniques of fabrication of CDs: Conventional CDs (CCD), Subtractive CDs (SCD), and Additive CDs (ACD). Each Group CDs were further divided into three sub groups based on occlusion schemes: bilateral balanced occlusion (BBO), lingualized occlusion (LO) and mono plane occlusion (MO). A total of 45 CDs were made: 15 in each group with 5 CDs of each occlusal scheme. For all samples, occlusal force analysis (percentage of occlusal force applied on the right and left sides of the arch, centralization of forces and percentage of maximum occlusal force) was done using computerized occlusal analysis system: T-scan III. Univariate regression analysis and logistic regression analysis were used to find the effects of the technique of fabrication and occlusion scheme over the occlusal forces (p< 0.05). RESULTS: The intergroup comparison revealed statistically significant differences (p< 0.01) in Right – Left side force difference, maximum bite force in CDs fabricated by various techniques and with different occlusion schemes. Though the effect of occlusion scheme was more than the technique of fabrication (according to effect size estimation). The maximum force difference between Right – Left side was observed in combination of CCD technique and MO scheme (36.88 ± 2.82 N). Furthermore, the maximum bite force was observed for SCD technique (89.14 ± 6.08 N) and LO scheme (92.17 ± 3.22 N). In comparison to ACD, the chances of centre of force out of ellipse was 2.53 time more in CCS and 0.75 times less in SCD techniques and in comparison to MO, the chances of out of ellipse was 0.298 times less in BBO and 0.396 times less in LO schemes, though these chances were not statistically significant (p> 0.05). CONCLUSIONS: The digital CDs fabricated by subtractive technique were proved to be superior to additive technique in terms of occlusal force analysis on tested parameters. However, further research is needed on patients to determine the exact superiority of one technique over the other.

Background: The Educational Environment (EE) has an extremely important role in effective student learning. The Dundee Ready Education Environment Measure (DREEM) is a validated and widely tool to assess the EE in health and particularly in dental professional education programs. Objective: This study aimed to compare male and female dental students' perception regarding DREEM inventory of EE in Jazan University. A cross-sectional questionnaire included questions on demographic information and the DREEM of EEs. Methods: DREEM was used to gather information from our BDS students’ program about the environment in our institution. The data were selected from 3rd, 4th, 5th, 6th year students. Data from 330 participants were distributed manually. Other factors such as type of graduated school, level of education, student’s GPA, and monthly income of family were assessed. All the data were analyzed. Results: 286 (86%) of the students completed and returned the DREEM questionnaires. There was no statistically significant difference between genders with respect to mean scores of perceptions of learning. Also, there was a significant difference in terms of educational level, but no significant differences were observed in the DREEM subscales. The average overall DREEM score of the study subjects indicated a positive learning perception of 130.8 for males and 130.2 for females. The subscale for both genders involved students’ perception of learning as 32.1, the students’ perception of teaching as 29.1, while the students’ academic self-perception was 21.7. The students’ self-perception of atmosphere was 30.0 while students’ social self-perception accounted for 17.5. Conclusion: Both gender students recorded positive values of the learning environment. Further, a qualitative investigation is recommended to be done on every single course to evaluate the changes and make necessary alterations.