The Influence of Ferrule Design and Pulpal Extensions on the Accuracy of Fit and the Fracture Resistance of Zirconia-Reinforced Lithium Silicate Endocrowns.

The study aimed to assess the marginal, axial, and internal adaptation, as well as the fracture resistance of zirconia-reinforced lithium silicate (ZLS) endocrowns with varying pulpal inlay extensions and marginal geometry. Sixty extracted maxillary first molar teeth were divided into six groups (n = 10) according to pulpal inlay extension and marginal configuration. The first three groups (J2, J3, and J4) utilized prepared teeth for endocrowns without ferrule design and 2 mm, 3 mm, and 4 mm pulpal extensions, respectively. The second three groups (F2, F3, and F4) utilized prepared teeth with 1 mm shoulder margins and 2 mm, 3 mm, and 4 mm pulpal extensions. The endocrowns were fabricated from ZLS blocks using CAD/CAM milling technology. After cementation, the specimens underwent thermal aging for 5000 cycles and were evaluated for marginal adaptation. Using a universal testing machine, the fracture resistance was tested under quasistatic loading (1 mm/min). Two-way ANOVA and the Tukey's post hoc test were employed for data analysis (p ≤ 0.05). The results of this study revealed that endocrowns without ferrule exhibited superior fracture strength than a 1 mm ferrule design p < 0.05, irrespective of the inlay depth. All designs with and without ferrule and all inlay depths showed clinically acceptable marginal and internal fit. The conventional endocrown design without ferrule and 2 mm inlay depth showed the lowest surface gap. The pulpal surface showed the highest discrepancy among all groups compared to the other surfaces. Endocrowns without ferrule are more conservative and have higher fracture strength than 1 mm ferrule designs; extending the inlay depth showed a significant increase in fracture resistance of the 1 mm ferrule design, but not for the conventional design without ferrule and 2 mm inlay depth. All groups exhibited a high auspicious fracture strength value for molar endocrown restorations.

Evaluating the pH of Various Commercially Available Beverages in Pakistan: Impact of Highly Acidic Beverages on the Surface Hardness and Weight Loss of Human Teeth.

The objectives of this study were to investigate the pH of common beverages and to evaluate the effects of common acidic beverages on the surface hardness and weight loss of human tooth specimens. A total of 106 beverages were conveniently purchased from supermarkets in Karachi, Pakistan. Prior to evaluation, beverages were refrigerated or stored at room temperature in accordance with the manufacturers' recommendations. Beverages were categorized into six groups: 'Sports and Energy drinks', 'Water', 'Fruit Juices and Drinks', 'Sodas', 'Milk and Flavored Milk' and 'Teas and Coffee'. Using a pH meter, the pH of each beverage was measured in triplicate at room temperature. In addition, the influence of five highly acidic beverages on the weight loss and surface hardness of human tooth specimens was evaluated using gravimetric analysis and the Vickers hardness tester, respectively. 'Sports and Energy drinks', 'Fruits Juices and Drinks' and 'Sodas' were the most acidic beverage categories, with a pH range of 3.00−5.00. A total of 33% of beverages tested in this study were highly acidic (pH less than 4.00), 29% of beverages were moderately acidic (pH 4.00−4.99) and 31% were mildly acidic (pH 5.00−6.99). Significant weight loss was observed in all immersed specimens compared to control counterparts (p < 0.05). Similarly, for surface hardness, five highly acidic beverages (Red Bull, Pepsi, Apple Cidra, Tang Mosambi and Tang Orange) significantly decreased the surface hardness of specimens (p < 0.05). The pH levels of commonly available beverages in Pakistan are highly acidic, which may encourage loss of minerals from teeth; hence, affecting their surface hardness.

Preferred Learning Styles of Dental Students in Madinah, Saudi Arabia: Bridging the Gender Gap.

Purpose: Currently, the dental education system in Saudi Arabia is gender segregated. It is important to find out whether teaching methods must be altered to improve the learning experience for both genders throughout their years of study. This study aims to investigate the preferred learning styles for males and females studying dentistry at Taibah University, Madinah, Saudi Arabia and the effect of academic level on the learning style preference. Materials and Methods: A cross-sectional survey composed of the visual, aural, read/write, kinesthetic (VARK) questionnaire was distributed to 228 undergraduate dental students at Taibah University through emails during September/October 2020. Student learning styles were presented using descriptive statistics. Learning preferences between genders and academic years were compared using independent proportional t-test and Chi-square test. Results: A total of 168 dental students completed the questionnaire. Both genders displayed a higher percentage of a unimodal learning preference (60% males, 50% females) with 41% of males preferring the kinesthetic learning style, followed by the aural (26%) then the visual (20%), and lastly read/write learning style (12.6%). Female students preferred the kinesthetic learning style (42%), followed by the visual (27%) then the aural (20%), and lastly read/write learning style (11%). All students throughout the 6 academic years preferred the unimodal learning approach with the kinesthetic style favored. The quadmodal was preferred mostly by interns. Conclusion: Both male and female students studying dentistry at Taibah University had a unimodal learning preference. Quadmodal learning was popular among interns. Both genders preferred the kinesthetic learning style, followed by the aural for males and visual for females. Teaching methods must be tailored to suit the learning style of each gender to promote motivation and thriving for a successful outcome.

Multidisciplinary management of congenitally missing lateral incisors: A minimally invasive approach.

The following case report demonstrates how a multidisciplinary team approach can be utilized successfully for the minimally invasive esthetic treatment of congenitally missing maxillary lateral incisors through space closure and canine re-anatomization.

Dental and Oral Manifestations of COVID-19 Related Mucormycosis: Diagnoses, Management Strategies and Outcomes.

It has been nearly two years since the pandemic caused by the novel coronavirus disease (COVID-19) has affected the world. Several innovations and discoveries related to COVID-19 are surfacing every day and new problems associated with the COVID-19 virus are also coming to light. A similar situation is with the emergence of deep invasive fungal infections associated with severe acute respiratory syndrome 2 (SARS-CoV-2). Recent literature reported the cases of pulmonary and rhino-cerebral fungal infections appearing in patients previously infected by COVID-19. Histopathological analysis of these cases has shown that most of such infections are diagnosed as mucormycosis or aspergillosis. Rhino-orbital-cerebral mucormycosis usually affects the maxillary sinus with involvement of maxillary teeth, orbits, and ethmoidal sinuses. Diabetes mellitus is an independent risk factor for both COVID-19 as well as mucormycosis. At this point, there is scanty data on the subject and most of the published literature comprises of either case reports or case series with no long-term data available. The aim of this review paper is to present the characteristics of COVID-19 related mucormycosis and associated clinical features, outcome, diagnostic and management strategies. A prompt diagnosis and aggressive treatment planning can surely benefit these patients.

Impact of the Haptic Virtual Reality Simulator on Dental Students' Psychomotor Skills in Preclinical Operative Dentistry.

One of the current trends in dental education is to empower dental students on a global platform using advanced technology. Haptic virtual reality simulation (HVRS) is a relatively new technology in the field of teaching and learning operative dentistry. This study aims to assess the impact of haptic virtual reality simulation (HVRS) on dental students' psychomotor skills acquisition in preclinical operative dentistry. Class I cavity preparations (CP) were performed at baseline by 21 novice dental students on plastic teeth. Duration of CP was recorded and cavity features were evaluated and scored. Then, students were exposed to HVRS training on CP. Another Class I CP was performed by each student on plastic teeth after HVRS training, then evaluated, and the duration was recorded. There was a statistically significant decrease in CP performance time after HVRS training (p < 0.001) and an increase in the mean total marks of CP after HVRS training (p < 0.001). The change in the students' performance in the CP displayed a statistically significant improvement after HVRS training in smoothness of the pulpal floor (p = 0.047), pulpal floor direction (p = 0.029), buccal, lingual, and mesial wall direction (p = 0.004, p = 0.025, p = 0.002), mesial and distal wall smoothness (p = 0.01, p = 0.001), internal line angle (p = 0.024), and internal point angle (p = 0.029). Overall improved performance in psychomotor skills was found after HVRS training. It could be beneficial to incorporate HVRS training early in pre-clinical operative dentistry courses as an adjunct to conventional phantom head training.

Influence of Surface Modification Protocol and Type of Luting Cement on Bonding of Monolithic Zirconia to Dentin Substrate.

AIM AND OBJECTIVE: To assess microtensile bond strength (µTBS) of two types of luting cement to monolithic zirconia and dentin following various surface modifications and aging. MATERIALS AND METHODS: Monolithic zirconia blocks were divided into four main groups. Group N: no surface modification; Group SB: sandblasted using 50 µm Al2O3 particles. Group GH: glazed with a thin film of low-fusing porcelain glaze and etched with 10% hydrofluoric acid for 60 seconds. Group CJ: sandblasted with CoJet sand. Surface-treated ceramic blocks were bonded to dentin using either self-adhesive cement or resin-modified glass ionomer cement and submitted to 3 or 150 days of water storage protocol with aging. The specimens were subjected to tensile force until de-bonding. Surface roughness (Ra, µm) was assessed after surface treatment. Analysis of variance (ANOVA) tests followed by Tukey's tests were used to analyze the data (α = 0.05). RESULTS: Surface modification using selective infiltration etching (SIE) showed significantly higher µTBS (p < 0.05) compared to tribochemical silica coating, sandblasting, and no treatment groups. The surface roughness of the SB and CJ groups were statistically higher compared to GH and N groups. CONCLUSION: Selective glass infiltration etching was an effective method in altering the surface properties, creating a strong and durable bond to monolithic zirconia. CLINICAL SIGNIFICANCE: Surface treatment procedures using SIE techniques combined with the use of universal 10-Methacryloyloxydecyl dihydrogen phosphate (MDP)-containing adhesives could establish a long-lasting and strong bonding to monolithic zirconia restorations. Resin-modified glass-ionomer cement (RMGIC) is an alternative luting cement for monolithic zirconia based on the assessment of its bond strength and bond durability.

Evaluation of the efficacy of calcium silicate vs. glass ionomer cement indirect pulp capping and restoration assessment criteria: a randomised controlled clinical trial-2-year results.

OBJECTIVES: Assess calcium silicate cement (Biodentine™) vs. glass ionomer cement (Fuji IX™, control) as indirect pulp capping (IPC) materials in patients with reversible pulpitis after a 2-year follow-up. Evaluate the integrity of the overlying resin composite restorations using modified USPHS criteria and FDI criteria. Investigate the sensitivity of the modified USPHS criteria compared to the FDI criteria in the assessment of the restorations. MATERIALS AND METHODS: Seventy-two restorations (36 Biodentine™, 36 Fuji IX™) were placed randomly in 53 patients. Periapical radiographs were taken at pre-treatment (T0), 12-month (T12), and 24-month (T24) review. Restorations were assessed using the modified USPHS and FDI criteria at T12 and T24. RESULTS: At 24 months, 15 teeth had failed to maintain vitality (6 Biodentine™, 9 Fuji IX™). Clinical success rate of IPC for both materials was 72% and is related to the intensity of reversible pulpitis symptoms. No difference was found between T12 and T24 in the periapical (PA) radiographs and in the integrity of the resin composite restorations overlying Biodentine™ compared to Fuji IX™. There was no difference in the efficacy of the USPHS criteria compared to the FDI criteria in the assessment of the resin composite restorations. CONCLUSIONS: Biodentine™ and Fuji IX™ were clinically effective when used as IPC materials in teeth with reversible pulpitis at T24. Resin composite restorations overlying both materials performed well at T24. Using the USPHS or FDI criteria is equally efficient at T24; however, longer term follow-up is needed to establish whether there are sensitivity differences between these assessment criteria. CLINICAL SIGNIFICANCE: Teeth with deep carious lesions approaching the pulp and with signs of reversible pulpitis can be treated successfully by indirect pulp capping using either Biodentine™ or Fuji IX™. Using the USPHS or FDI criteria to assess restorations is equally effective at 2 years. TRIAL REGISTRATION: NCT02201641.

The physical characteristics of resin composite-calcium silicate interface as part of a layered/laminate adhesive restoration.

OBJECTIVES: To compare in-vitro micro-shear bond strengths (µSBS) of resin composite to calcium silicate cement (Biodentine™) vs. glass ionomer cement vs. resin modified glass ionomer cement (RM-GIC) using an adhesive in self-etch (SE)/total etch (TE) mode after aging three substrates and bond and characterizing their failure modes. METHODS: Resin composite was SE/TE bonded to 920 standardized disks of Biodentine™, GIC & RM-GIC. Dividing samples into two groups, the first underwent early (t=0min, 5min, 20min, 24h) or delayed (t=2wk, 1 month, 3 months, 6 months) substrate aging before bonding and µSBS (t=24h) testing. In the second, adhesive was applied after either early (t=5min) or delayed (t=2wk) substrate aging and then tested after bond aging (t=2wk, 1 month, 3 months, 6 months). The failure modes were identified using stereomicroscope. SEM images of selected samples were analyzed. RESULTS: No significant differences were observed between (SE)/(TE) bonding modes (P=0.42). With substrate aging, a significant reduction in µSBS occurred between early and delayed time intervals for Biodentine™ (P=0.001), but none for the GIC/RM-GIC (P=0.465, P=0.512 respectively). With bond aging, there was no significant difference between time intervals for all groups, except at 6 months for the GIC (P<0.05). Modes of failure were primarily cohesive within all the substrates (68.82%) followed by adhesive failure at the resin-substrate interface (21.71%). SIGNIFICANCE: Biodentine™ is a weak restorative material in its early setting phase. Placing the overlying resin composite as part of the laminate/layered definitive restoration is best delayed for >2wk to allow sufficient intrinsic maturation to withstand contraction forces from the resin composite. A total-etch or self-etch adhesive may be used.

An in vitro comparison of the accuracy of measurements obtained from high- and low-resolution cone-beam computed tomography scans.

INTRODUCTION: This study aimed to investigate in an ex vivo model the reduction in patient radiation dose while maintaining accurate linear measurements by comparing cone-beam computed tomography (CBCT) scans taken at 360° versus 180° rotation, with porcine jaw specimens as a reference standard. METHODS: CBCT scans of 12 sectioned porcine hemimandibles at 360° and 180° rotations were taken with standardized clinical exposure parameters. To assess interobserver variability, 6 assessors who were blinded to the degree of rotation took linear measurements of anatomic structures on each scan. The measurements were repeated after 2 weeks to assess intraobserver variability. Accuracy of measurement was judged against the corresponding measurements taken from the porcine jaw specimens. RESULTS: Intraclass correlations signaled good-to-excellent intraobserver and interobserver agreement (0.65-0.98 and 0.79-0.98), respectively. Mixed regression analysis found no significant difference between the measurements from 180° or 360° rotations and no difference between the 2 rotations and porcine jaw specimens. CONCLUSIONS: A CBCT image sufficient to make accurate clinical measurements with a reduced radiation exposure may be obtained by using 180° rotation of the CBCT tube head.

The effect on cast post dimensions of casting investment and airborne particle abrasion.

Cast posts can sometimes prove difficult to seat fully during fitting. This study compared two different liquid/water dilutions for phosphate bonded investment and the effect of controlled airborne particle abrasion on resulting post diameter. After measuring polymeric post patterns (n = 18), 3 groups were invested using concentrated solution and 3 groups using dilute solution. After casting they were weighed and remeasured then exposed to airborne particle abrasion. Both solutions produced oversized cast posts. Mean diameter reduction during airborne particle abrasion was 8 microm/10s taking an average of 41s to reach precast size. Where a post pattern fits tightly, airborne particle abrasion for 70s should reduce the casting sufficiently to accommodate the cement lute.