FRACTURE TOUGHNESS AND FRACTURE MODE OF CEMENT-RETAINED VERSUS SCREW-RETRIEVABLE CEMENT-RETAINED IMPLANT-SUPPORTED CROWNS: A PILOT STUDY The aim of this pilot study was to compare the fracture toughness and fracture mode of cement-retained versus screw-retrievable cement-retained implant-supported monolithic zirconia crowns. Ten implant-supported crowns were made from monolithic CAD/CAM zirconia and equally divided into control and test groups. The control group received cement-retained monolithic zirconia crowns (CR), while the test group received screw-retrievable cement-retained monolithic zirconia crowns (SRCR). The crowns were then bonded to prefabricated Variobase titanium-based abutments with resin luting cement. To simulate the aging process in the oral cavity, all samples were undergone thermal cycling machine. After ageing, each group underwent a single load fracture test to analyze the fracture load, and the fracture mode was evaluated using scanning electron microscopy (SEM). The Mann-Whitney U test was used to compare fracture toughness, and statistical significance was set at p<0.05. The mean fracture toughness of CR crowns was 2945.49 ± 511.426 N, while that of SRCR crowns was 2897.82 ± 510.837 N, but the difference was not significant (U=10, p= 0.917). SEM examination revealed that all failures originated from the fitting surface of the crowns. The titanium-based abutment remained intact in all specimens. Within the limitations of this pilot study, the CR showed higher fracture toughness than SRCR implant crown, but both specimen fracture at six times more than the average maximum bite force of posterior tooth. The presence of screw access in SRCR has affected the fracture mode.

Introduction: This study aims to explore the dental students’ educational experience, the protocol consideration after school reopening and their physical health during the COVID-19 pandemic. Secondly, to evaluate the anxiety level of dental students during the COVID-19 pandemic. Method: A cross-sectional survey was distributed with a hyperlink, reported as frequencies and percentages. A univariate analysis was used to explore the significant associations between demographic variables and anxiety levels. The risk factor was also identified using regression analysis. A two-tailed p<0.25 was considered significant. Results: A total of 333 respondents participated in the survey. Half of the respondents (42.3%) were comfortable with distance learning but worried about passing their examination and completing their clinical requirements. The transitioning to the online course by the lecturer was documented as effective. Despite missing academic sessions, only 15.3% were willing to replace the loss of educational experience. The majority of students (85.9%) believed that masks should be worn in school, but varied perceptions on wearing gloves and frequent COVID-19 testing. For physical health, mostly concerned about contracting the virus after the school reopens. For their anxiety level, nearly half have mild (n=99), moderate (n=55), and severe (n=36) levels. The factors were mainly associated with gender, household income, type of university, and respondent’s accommodation. Conclusion: As positive feedback was recorded towards online learning, constant improvement is needed to ensure the possibility of hybrid learning, even after the pandemic. The physical and psychological health of dental students should be a priority, to ensure a smooth transition during these unprecedented circumstances.

Immediate implant placement into fresh extraction sockets has gained a lot of attention in implant dentistry. Besides proper risk assessment, the evaluation of tooth anatomy aids the clinicians to select the finest treatment protocol. Cone Beam Computed Tomography (CBCT) imaging was frequently used for alveolar bone analysis prior to tooth extraction in immediate implant placement. As an ideal position is required to prevent a buccally tilted implant or too palatal implant placement, various authors have proposed the treatment guidelines for immediate implant placement in the anterior maxilla. Although insightful, the previous classification was lacking anatomic variant and key anatomical features of alveolar bone and tooth angulation. Furthermore, there is no standardization method of measuring the specific degree of tooth angulation in CBCT scans that could possibly be used in clinical setting for appropriate treatment protocol. Thus, it is essential for the clinician to have adequate knowledge on the role of facial alveolar bone, palatal alveolar bone and tooth angulation related to immediate implant before selecting the appropriate treatment guidelines based on the classification reviewed. In this review, the previous quantitative measurements were categorized, and the previous classification was listed for the sake of familiarity by the dental practitioner with the major updates on implant placement strategy, patient selection and to reduce the rate of surgical complications.