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.

Dentinal hypersensitivity (DH) is a condition that causes patient discomfort. To evaluate the clinical efficacy of Gluma, fluoride varnish and Tetric N-Bond self-etch system in relieving DH immediately and over 30 days following a single topical application. The present randomized clinical trial was conducted on 55 patients with an age range 20–49 years. 70 teeth in total were incorporated and randomly assigned to the three groups. Parameters examined were: Tactile, air blast, and cold stimuli. VAS was used to assess tactile stimulus whereas the Schiff Cold Scale for air blast and cold stimuli. DH was evaluated immediately, at two weeks and 1 month follow up. Gluma showed a statistically significant reduction in DH scores over other materials. It was concluded that Gluma have statistically significant results over other materials in relieving DH immediately and over 30 days following a single topical application.Trial Registration: Clinical Trials.gov Identifier: NCT04351412, King Abdulaziz University Protocol Record 129-09-19. Registered 17 April 2020 – Retrospectively registered. http://ClinicalTrials.gov/NCT04351412.

Zein-incorporated magnesium oxide nanoparticles (zMgO NPs) were found to be effective against the bacteria S. mutans, S. aureus, E. faecalis and C. albicans, and can impart this antimicrobial effect on the resin composite it is integrated with. However, the effect of different light curing systems on the mechanical properties of this novel biomaterial has yet to be investigated. The objective of this study was to assess the effect of light-emitting diode (LED) and quarts-tungsten halogen (QTH) light curing systems on the compressive strength, flexural strength, and microhardness of bulk-fill resin composite modified with zMgO NPs. A Teflon mold was used to fabricate 180 bulk-fill composite samples with concentrations of zMgO NPs at 0%, 0.3% and 0.5% (n = 60). Samples of each group were allocated to light curing by LED or QTH, after which 10 samples of each group were allotted to a mechanical test. Characterization of the specimens was performed by X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. Two-way ANOVA and Tukey's post-hoc test was conducted at P = .05 to determine significance. The characterization revealed a uniform distribution of nanoparticles in the matrix and the formation of a new hybrid composite that maintained its properties. The compressive strength of the 0.3% zMgO composite for the QTH group significantly increased, while the remaining groups underwent no significant change. There was no significant difference among the groups for the flexural strength and microhardness tests. The modified composites' compressive strength, flexural strength, and microhardness improved or remained consistent. Long-term clinical studies can further substantiate the enhanced resin composite. The modified composite will exhibit similar or improved mechanical properties whether an LED or QTH light cure device is used. The addition of an antimicrobial effect to bulk-fill resin composite will aid in the prevention of secondary caries.

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.

When planning a whitening or bleaching procedure, it is essential to use either indirect or direct tooth-colored restorative materials that closely match the natural tooth shade. This study aimed to investigate the effects of home bleaching agents on the surface texture of these materials, specifically focusing on restorative dental biomaterials. Two types of commercially available resin composites, packable and flowable, were selected as the tooth-colored materials under investigation. A total of 40 specimens were prepared following standard protocols to evaluate the effect of different concentrations of bleaching agents on surface roughness before and after treatment. A statistically significant increase in surface roughness was observed, with values increasing from 7.18 ± 4.62 to 101.30 ± 11.32 after the use of bleaching agents. However, no significant difference was found between the roughness of packable and flowable composites. Similarly, variations in bleaching agent concentration did not produce a statistically significant effect. The findings indicate that bleaching agents contribute to the degradation of tooth-colored restorative materials, leading to increased surface roughness after treatment compared to baseline levels. The flowable composites showed a similar susceptibility to bleaching effects as the packable composites. Regardless of concentration, both tested bleaching agents caused comparable increases in surface roughness in the resin-based composites.