Objective: To investigate the flexural strength of hot isostatically pressed nano 3 mol% yttria partially stabilised zirconia and conventionally sintered micro 3 mole% yttria partially stabilised zirconia. Methods: A total of 40 bar-shaped (2 mm × 4 mm × 16 mm) specimens were prepared from hot isostatically pressed nano 3 mol% yttria partially stabilised zirconia (CeramaZirc Nano HIP, Precision Ceramics) and conventionally sintered micro 3 mole% yttria partially stabilised zirconia (CeramaZirc, Precision Ceramics). Two groups were prepared for each material (n = 10), with one serving as ‘control’ and the other being cyclically loaded using a chewing simulator (7 kg; 250 k cycles): SEM imaging was also undertaken on selected specimens. Flexural strength until fracture was recorded (ISO 6872). Paired and unpaired t-tests were chosen to compare mean outcomes between the four groups (p < 0.05). Results: Significant statistical difference was only found between the means of control specimens. CeramaZirc Nano HIP had the highest mean value (1048.9 MPa), whilst the lowest was seen for CeramaZirc after loading (770 MPa). Values for both materials were higher without loading than after loading. Values after cyclical loading showed large SD values (276.2–331.8) in comparison to ‘control’ (66.5–100.3). SEM imaging after cyclical loading revealed a smoother and less destructed surface of CeramaZirc Nano HIP compared to CeramaZirc. Significance: HIP nano zirconia exhibited inferior strength, surface polishability and behaviour to loading. Therefore, further investigation on the behaviour of such materials should be conducted before recommending for clinical use.

Objective: To evaluate the effect of deep margin elevation (DME) and immediate dentin sealing (IDS) on the fracture strength of premolars restored with lithium disilicate inlay restorations.Materials and Methods: Standard MOD inlays with proximal box preparations extending 3 mm apical to the cementoenamel junction were prepared on forty sound premolars (n = 10) randomly divided into four groups: inlays without DME and without IDS (G1); inlays without DME but with IDS (G2); inlays with DME but without IDS (G3); and inlays with both techniques applied (G4). Composite resin was applied incrementally to elevate the proximal cervical margin coronally to the cementoenamel junction. For immediate dentin sealing, bonding agent was applied immediately after tooth preparation. All teeth were restored with lithium disilicate inlays and, after adhesive resin cementation, specimens were thermomechanically aged for 500 cycles at 5°–55°C and then subjected to load failure testing. Failure loads and locations were recorded and analyzed using one‐ and two‐way ANOVA with Tukey's post‐hoc testing (α = 0.05). Failure modes were analyzed using descriptive statistics.Results: The mean fracture loads were 565.76 ± 233.22 N, 978.47 ± 394.2 N, 974.31 ± 334.7 N, and 1108.21 ± 292.41 N for G1, G2, G3, and G4, respectively. Deep margin elevation (p = 0.011) and immediate dentin sealing (p = 0.010) were associated with significantly increased fracture loads. Fracture loads were significantly lower for G1 teeth than for G2‐G4 teeth, but there were no significant differences between G2, G3, and G4. G1 teeth showed 50% catastrophic and non‐catastrophic failures, which increased to 60% for G2 and decreased to 20% for G3 teeth. Samples with both seals and elevation (G4) had a 60% catastrophic failure rate.Conclusions: When applied individually or together, deep margin elevation and immediate dentin sealing significantly increase the fracture strength of premolars restored with indirect lithium disilicate inlays.Clinical Implications: In the challenging setting of margin elevation, studies on the effects of immediate dentin sealing have generally been limited to evaluating marginal integrity and bond strength. The findings of this In Vitro study suggest that both deep margin elevation and immediate dentin sealing protocols are likely to improve clinical outcomes of indirect lithium disilicate inlay restorations and may be considered viable options in clinical practice.

BACKGROUND: Evaluating the oral histology curriculum offers critical insights into effective teaching strategies and curriculum design to optimize learning outcomes. This study examines the strengths and weaknesses of the current oral histology curriculum and explores teaching and learning methods employed in a Saudi dental school from the students’ perspective, offering recommendations for future curriculum enhancements. MATERIALS AND METHODS: This cross-sectional study involved 80 students (40 males and 40 females) who attended oral histology lectures and lab sessions at the Faculty of Dentistry, King Abdulaziz University, during the 2022-2023 academic year. A pre-structured and pre-tested online questionnaire comprising 24 questions, divided into 7 sections to cover different aspects of the oral histology course, was used. Descriptive statistical analysis of responses was conducted using SPSS version 26. RESULTS: The study revealed a strong consensus on the importance of the course, with high levels of agreement regarding the clarity of objectives (72%) and course organization (69%). High engagement levels were noted in both class and lab sessions, with a preference for diverse teaching methods. Male and female participants agreed on the difficulty but recognized the critical importance of the oral histology course. However, opinions varied on teaching methods that encourage participation ( P = .0001), continuous assessments ( P = .004), and class attendance ( P = .030). Most aspects of the course showed no significant gender differences. CONCLUSION: This study highlights the need for refinement in the oral histology curriculum, focusing on enhanced teaching methods and gender-specific participation and assessment needs. Improving continuous assessments, attendance strategies, and interactive learning approaches can further boost student engagement and optimize educational outcomes.

To assess and compare the trueness (dimensional discrepancy and degree of deviation) of various methods of impressions for All-on-4 implants. This investigation employed a single-piece artificial mandibular jaw with four implants arranged in an All-on-4 configuration. Three impression methods were compared: one open-tray conventional impression digitized after pouring, and two intraoral scanners, TRIOS 5 and Runyes 3DS 3.0. A reference scan (control) was conducted with a laboratory-based scanner. All scans were performed using scan bodies and exported as Standard Tessellation Language (STL) files. A total of 30 STL scans were produced (n = 10). The dimensional discrepancy (along the X, Y, and Z axes) and the overall degree of deviation in the position were assessed. Data analysis was conducted using Brown–Forsythe one-way analysis of variance and Tamhane's post hoc tests (p < 0.05). The mean degree of deviation for scan bodies was as follows: TRIOS 5 (1.11 ± 0.06 mm), Runyes 3DS (1.02 ± 0.05 mm), and conventional (0.82 ± 0.16 mm). Statistically significant differences were found among all impression methods (p < 0.05). While the conventional method showed the highest trueness, it had the greatest standard deviation (SD, 0.16), which was the least consistent among them. The Runyes 3DS scans displayed the highest precision with the degree of deviation of 0.05 (± SD). Dimensional discrepancies mainly occur on the Z-axis across all three impression methods. Conventional impressions showed statistically significant discrepancies in the Y- and Z-axes, while TRIOS 5 images had statistically significant discrepancies in the X- and Z-axes. Runyes 3DS readings were statistically significantly discrepant in the Z-axis. While both conventional methods and digital scans have their merits, traditional impression methods may offer improved trueness in full-arch implant cases. Utilizing the open-tray system with suitable materials and methods can enhance precision and lead to more reliable outcomes.

Background: Fiber-reinforced posts (FRPs) are preferred for the rehabilitation of endodontically treated teeth. Achieving adequate bond strength between resin cement and root dentin requires effective removal of the smear layer and debris from the post space before cementation. The aim of this study is to evaluate the effect of various post space cleaning methods prior to cementation of fiber-reinforced posts on the push-out bond strength (PBS). Methods: Ninety-one human premolars underwent root canal treatment, post space preparation and were assigned to seven groups, each using a different cleaning method. These included normal saline (control), sodium hypochlorite, chlorhexidine, EDTA, air abrasion, Katana™ Cleaner, and phosphoric acid. Tapered fiber-reinforced posts were cemented using self-adhesive resin cement. Two middle root slices from each tooth were obtained (26 specimens/group). Then, all specimens were subjected to thermocycling followed by push-out testing. Failure modes were evaluated under a stereomicroscope. Statistical analysis for PBS was performed using Kruskal-Wallis test and Chi-square test was used to analyze failure modes. Results: The mean PBS ± Standard deviation of all groups, ranked from highest to lowest were; Phosphoric Acid 26.61 ± 7.22 MPa, Chlorohexidine 21.33 ± 5.54 MPa, Sodium Hypochlorite 17.77 ± 4.37 MPa, EDTA 16.76 ± 4.54 MPa, air-born particle abrasion 15.72 ± 4.61 MPa, Katana ^™ Cleaner 15.48 ± 4.06 MPa, and Control 12.73 ± 3.53 MPa. The control group exhibited the lowest PBS, and only phosphoric acid, Chlorohexidine and Sodium Hypochlorite demonstrated significantly higher PBS than control group. A higher frequency of favorable failure mode (Failure Mode 1) was seen in groups treated with phosphoric acid (80%), chlorhexidine (90%), and EDTA (80%), all of which demonstrated higher push-out bond strengths. Conclusions: Post space cleaning significantly affects PBS. Failure to properly clean the post space before cementation negatively affects the post retention. Cleaning with phosphoric acid demonstrated the highest push-out bond strength, more than double that of control group, followed by chlorhexidine and sodium hypochlorite.

Objective To investigate the dimensional discrepancy and degree of deviation of All-on-Four implant position between different cone-beam computed tomography (CBCT) machines. Materials and Methods Four implants (4.5 × 10 mm Superline II, Dentium, South Korea) were placed in an All-on-Four style in an artificial mandible. The jaw was radiated 30 times using three different CBCT machines (Rainbow CT, Dentium; Veraview X800, Morita, Japan; Planmeca Viso G3, Planmeca OY, Finland). A total of 30 Digital Imaging and Communications in Medicine (DICOM) files were exported, n = 10. All-on-Four implants from each DICOM file were segmented and exported as an STL file (three-dimensional image) using Blue Sky Plan software (version 4.12.13/Blue Sky Bio, United States). All-on-Four implant zone dimensions (X, Y, and Z axes) and the total degree of deviation between All-on-Four implants per CBCT machine were measured using Autodesk Meshmixer software (version 3.5.474/California, United States). The data distribution's normality and variances' equality were tested with Shapiro–Wilk's and Levene's tests, respectively (p-value < 0.05). Data were analyzed using Brown–Forsythe one-way analysis of variance and Tamhane's post hoc tests to compare the differences between the groups (p-value <0.05). Results The respective X, Y, and Z mean dimensions of the All-on-Four implant zone were: Dentium (34.95, 14.71, and 9.97); Morita (34.88, 14.74, and 10.56); and Planmeca (34.73, 15.15, and 12.33). Significant differences between CBCT machines were found in all axes (p-value < 0.05); however, the Z-axis had the most differences. Notably, Planmeca exhibited the highest standard deviation (SD) in all axes (0.16–0.35), exhibiting the lowest consistency in the CBCT machines' readings. The Dentium exhibited the lowest deviation in the implant position, with the lowest SD (0.61). A significant difference in the total degree of deviation was spotted when only Morita was included in the comparison (p-value < 0.05). Conclusion This study's findings are of significant importance as they reveal that the implant position recorded from the CBCT machines was most discrepant in the buccolingual dimension (Z-axis). Planmeca exhibited the least implant-dimensional accuracy of the CBCT machines, while Dentium exhibited the highest implant position accuracy. These results could significantly impact the choice of CBCT machine for implant placement, especially since an accurate CBCT image is crucial for digital implant planning.