Background: Surgical root canal retreatment is required when peri-radicular pathosis associated with endodontically treated teeth cannot be treated by non-surgical root canal therapy (retreatment), or when retreatment was ineffective, not feasible or contraindicated. Endodontic failures maybe happen when irritants remain within the confines of the root canal, or when an extra-radicular infection cannot be eradicated by orthograde root canal treatment. Following enhanced microsurgical techniques in the last years, the success rates of surgical root canal retreatment have improved considerably. Objective: The aim of this systematic review is to gather updated data in regard to the surgical root canal (retrograde) retreatment to heal the periapical lesions. Materials and methods: The electronic databases PubMed and Google Scholar were searched in this review using specific inclusion and exclusion criteria. The search was performed in June 2019 and updated in November 2019. Among 3900 studies, 10 studies satisfied the eligibility criteria and were included in the review to be analyzed. Results: The 10 studies showed the importance of surgical root canal retreatment as a treatment option in removing infections within the root canal system and its efficiency in periapical tissue healing. These studies investigated different aspects of healing of periapical lesion after surgical (retrograde) retreatment including success rates, follow-up duration, and updated studies in surgical (retrograde) retreatment. Conclusions: Surgical root canal (retrograde) retreatment demonstrates its efficiency in reducing the period needed for healing of the periapical lesions in short-term follow-up compared to conventional orthograde retreatment.

Objectives: Many countries have enforced lockdowns on their populations due to the coronavirus disease 2019 (COVID‐19) pandemic. This study aimed to assess the effects of the lockdown on dental students.Methods: A longitudinal, repeated cross‐sectional study was conducted to evaluate psychological problems experienced by dental students during the COVID‐19 lockdown in Saudi Arabia. The dental students were selected from different universities using 2‐stage cluster sampling. The validated Arabic version of the 21‐item depression, anxiety, and stress scale questionnaire was distributed at the beginning and end of the lockdown. Mann–Whitney U and Kruskal–Wallis tests were used as appropriate. Chi‐square test was used to compare the proportions between the sociodemographic data, and logistic regression analysis was used to identify variables associated with the students’ responses.Results: A total of 1287 respondents participated in this study (695 first‐survey respondents, 592 second‐survey respondents). There were longitudinally significant differences in the students’ mental health outcomes based on gender, university, class year, and survey time during the COVID‐19 lockdown. The lockdown increased the likelihood of female, single, and junior students experiencing stress. The students who lived alone recorded a high chance of elevated levels of depression, anxiety, and stress, which showed a significant longitudinal reduction during the lockdown. Moreover, the lockdown increased the likelihood of mental health problems among the students staying in households of two persons or two‐five persons.Conclusions: This study indicates the importance of considering the detrimental mental health consequences on dental students in the event of future pandemics.

The growing use of 3D-printed dental restorations has created a need to understand how the mechanical behaviour of definitive 3D-printed resin composites compares with milled counterparts. This study compared the mechanical properties of 3D-printed and milled definitive crowns and examined the factors affecting these properties. The 3D-printed materials (Permanent Crown Resin: PCR, VarseoSmile Crown Plus: VCP, and Crowntec: CT) and milled blocks (Brilliant Crios: BC, Shofu Block HC: HC, and Grandio Blocs: Gr) were tested. Filler content was evaluated using the ash method (n = 3), and flexural strength (FS) and flexural modulus (E_f) were assessed using a three-point bending test (n = 10). Martens hardness (HM), indentation modulus, and Vickers hardness were determined using the Martens indentation test (n = 24). Vickers hardness was also measured with the Vickers indenter tester (n = 24). Statistical analysis investigated differences between materials and methods, and correlations between filler weight and mechanical properties (α = 0.05). FS of milled blocks, Gr (244.5 MPa), BC (225.5 MPa), and HC (155 MPa), were higher than that of the 3D-printed resin composites: PCR (143.6 MPa), CT (140.9 MPa), and VCP (128 MPa). Measured mechanical properties of the milled blocks were significantly higher than those of the 3D-printed materials (p < 0.001). HM of the 3D-printed materials was similar (≈217 N/mm²), while HM of the milled blocks ranged from 434.7 to 858.4 N/mm². The 3D-printed materials showed comparable properties; however, milled blocks differed significantly (p < 0.05). Filler content was strongly associated with FS and HM. Within the limitations of this study, the milled resin composites showed markedly higher strength and hardness, while 3D-printed materials may be suitable for low-to-moderate load clinical scenarios. Further studies to evaluate the long-term performance of the 3D-printed resin composites are recommended.

Background: Improved Lithium Disilicate Ceramic has been highly valued in dentistry for over two decades, owing to its durability and aesthetic qualities, making it a preferred choice for both anterior and posterior crowns. Objective: This study aimed to evaluate the flexural strength of two types of lithium disilicate blocks post-chewing simulation. Materials and Methods: Seventy-six lithium disilicate specimens were utilized in this study. They were divided into two primary groups (n=38) based on two brands: IPS Emax CAD LT (Ivoclar Vivadent) designated as (E), and Initial Lisi LT/B1 (GC America) designated as (L). Each primary group was further split into two subgroups (n=19) based on surface treatment: group E into (E0 & E1) and group L into (L0 & L1). Half of the specimens were subjected to flexural testing without chewing simulation cycles and designated as (E0 and L0), while the remainder were tested after 24× 10⁴ cycles of chewing simulation and designated as (E1 and L1). The ceramic surfaces were examined using SEM before and after loading. Statistical Analysis: Data were gathered, organized, and subjected to Shapiro–Wilk’s and Levene’s tests (p-value < 0.05), followed by analysis with Brown-Forsythe two-way ANOVA and Tamhane’s post hoc tests to assess group differences (p-value < 0.05). Results: There were significant statistical differences in the flexural strength values between the different brand groups before and after chewing simulation (p-value < 0.05). The IPS Emax CAD group showed values approximately twice that of the Initial Lisi group (307.2– 310.5 MPa ± 48.5– 67 vs 148.1– 158.5 MPa ± 24.6– 25.6). Conclusion: Within the limitation of the current study, the following may be concluded: 1. The study’s findings suggest that Initial Lisi blocks should not be used for posterior teeth restorations. 2. This study can provide valuable insights for dental professionals to make informed decisions about which material is most appropriate for various clinical situations.

Despite the widespread use of surgical guides, there is no universal sterilization protocol. Surgical guides are often designed for single use, but can become contaminated, which increases the risks of infection and implant failure. This study evaluates the effects of alcohol immersion, alcohol spray, low temperature, and steam sterilization on the dimensional stability of surgical guides to ensure accurate implant placement and reduce failure. One standard dental model was scanned using a laboratory scanner. Ninety guides were printed and were then divided into six groups allocated as control, alcohol spray, alcohol immersion with ultrasonication, low-temperature dry sterilization, and two autoclave methods. Specimens were stored in dry–dark media and scanned at 0, 3, and 7 days, with dimensional changes assessed using CloudCompare. The Shapiro–Wilk, Levene’s, Repeated measures one-way ANOVA, and Tukey’s post hoc tests were used to determine statistical differences. Time significantly affects stability, with RMS values improving over time. Autoclave 121 °C and low-temperature 54 °C sterilization showed the lowest RMS values, indicating better stability. Within the limitations of the present study, the most effective approach for maintaining the dimensional stability of surgical guides was autoclaving at 121 °C, +1 bar for 20 min, and the second-best technique was low-temperature dry sterilization at 54 °C for 1 h.

Introduction: Hypodontia or Dental agenesis; is defined as a developmental missing of any teeth, excluding the last molars. It may befall as a genetic syndrome or as a non-syndromic isolated trait. However, there is no prevalence available in our city. Aim and Objectives: The tenacity of this research is to assess the frequency of hypodontia among the population who received dental care at King Abdul Aziz University Dental Hospital in the city of Jeddah. Study Design: Retrospective digital orthopantomographic: cross-sectional study. Place and Duration of Study: Oral & Maxillofacial Prosthodontic Department, King Abdulaziz University, between January 2019 and July 2020. Methodology: This research is a retrospective cross-sectional study based on the examination of an archival dental record and 2D panoramic radiographs of patients who are presented at King Abdulaziz University Dental Hospital, Jeddah. A total of 2045 records were reviewed and included in this study. Two general practitioners reviewed patient’s dental charts looking for congenital missing tooth/teeth in a dark room by the method that the practitioners use. Careful reviews of each patient’s record were done to ensure that the cause of the missing tooth/teeth were congenital and not surgical or traumatic. Data were gathered from dental records of patients’ age period 6-9 years since most of the dental follicle of the permanent teeth should be completed or the tooth just erupts, radiographic findings were always compared to the patients’ file and progress notes to ensure the causative factors of missing teeth. The data were recorded in an excel sheet which included gender, age, the type, area and counting of the missing teeth. Results: After collecting the data, the total number of patients after exclusion were 1984. The prevalence of hypodontia in our tested population was %5.39. Statistical analysis were done by using SPSS software to correlate between variables. Varices grades. Conclusion: Within the limitations of this study our data shows that the most common congenitally tooth agenesis is the second premolar %47.6 and the second most common congenitally missing tooth is lateral incisor %18.6.