Mesenchymal Stem Cell-based Scaffolds in Regenerative Medicine of Dental Diseases.

Biomedical engineering breakthroughs and increased patient expectations and requests for more comprehensive care are propelling the field of regenerative dentistry forward at a fast pace. Stem cells (SCs), bioactive compounds, and scaffolds are the mainstays of tissue engineering, the backbone of regenerative dentistry. Repairing damaged teeth and gums is a significant scientific problem at present. Novel therapeutic approaches for tooth and periodontal healing have been inspired by tissue engineering based on mesenchymal stem cells (MSCs). Furthermore, as a component of the MSC secretome, extracellular vesicles (EVs) have been shown to contribute to periodontal tissue repair and regeneration. The scaffold, made of an artificial extracellular matrix (ECM), acts as a supporting structure for new cell development and tissue formation. To effectively promote cell development, a scaffold must be non-toxic, biodegradable, biologically compatible, low in immunogenicity, and safe. Due to its promising biological characteristics for cell regeneration, dental tissue engineering has recently received much attention for its use of natural or synthetic polymer scaffolds with excellent mechanical properties, such as small pore size and a high surface-to-volume ratio, as a matrix. Moreover, as a bioactive material for carrying MSC-EVs, the combined application of scaffolds and MSC-EVs has a better regenerative effect on dental diseases. In this paper, we discuss how MSCs and MSC-derived EV treatment may be used to regenerate damaged teeth, and we highlight the role of various scaffolds in this process.

Periodontitis and progression of gastrointestinal cancer: current knowledge and future perspective.

Periodontitis is a polymicrobial disorder caused by dysbiosis. Porphyromonas gingivalis (P.gingivalis) and Fusobacterium nucleatum (F.nucleatum) are pathobiont related to periodontitis pathogenesis and were found to be abundant in the intestinal mucosa of inflammatory bowel disease (IBD) and colorectal cancer (CRC) patients. Besides, periodontal infections have been found in a variety of tissues and organs, indicating that periodontitis is not just an inflammation limited to the oral cavity. Considering the possible translocation of pathobiont from the oral cavity to the gastrointestinal (GI) tract, this study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the relationship between periodontitis and GI malignancies by focusing on the oral/gut axis.

The homeostasis and therapeutic applications of innate and adaptive immune cells in periodontitis.

OBJECTIVES: Periodontitis (PD) is one of the most common dental disorders. This chronic oral inflammation is caused by complicated interrelations between bacterial infections, dysregulated immune reactions, and environmental risk factors. A dysregulated immune response can lead to inflammatory bone resorption by allowing the recruitment of pro-inflammatory immune cells to the periodontal tissues. SUBJECTS: The recruitment of innate and adaptive immune cells in PD initiates the acute and following chronic inflammatory processes. The inflamed tissues, on the other hand, can be restored if the anti-inflammatory lineages are predominantly established in the periodontal tissues. Therefore, we aimed to review the published literature to provide an overview of the existing knowledge about the role of immune cells in PD, as well as their possible therapeutic applications. RESULTS: Experimental studies showed that drugs/systems that negatively regulate inflammatory cells in the body, as well as interventions aimed at increasing the number of anti-inflammatory cells such as Tregs and Bregs, can both help in the healing process of PD. CONCLUSION: Targeting immune cells or their positive/negative manipulations has been demonstrated to be an effective therapeutic method. However, to use this sort of immunotherapy in humans, further pre-clinical investigations, as well as randomized clinical trials, are required.

Magnitude of misfit threshold in implant-supported restorations: A systematic review.

STATEMENT OF PROBLEM: Attaining a passive fit in implant restorations is desirable but clinically difficult to achieve, especially in screw-retained prostheses. At a certain magnitude, this misfit will not cause mechanical and biological complications, but the exact level has yet to be determined. PURPOSE: The purpose of this systematic review was to gather, compare, and appraise studies that attempted to determine the biological and mechanical tolerance of misfits. MATERIAL AND METHODS: The review protocol was published in the Prospective Register for Systematic Reviews (PROSPERO; registration no. CRD42021268399) and follows the Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. An electronic search was conducted through PubMed, Ebscohost, and Web of Science followed by a manual search up to December 2021. RESULTS: A total of 413 manuscripts were identified by electronic and manual search. After removing duplicates, nonrelevant titles, and abstract screening, 62 manuscripts were eligible for full-text assessment. Finally, a total of 13 articles (1 cross-sectional study, 1 retrospective and prospective, 7 in vitro studies, and 4 animal studies) met the eligibility criteria and were included in this review. A wide range of tolerable misfits were reported. Vertical misfit up to 1 mm and horizontal misfit up to 345 µm were associated with no adverse outcomes. CONCLUSIONS: The current literature provides inadequate data to determine a clinical threshold of an acceptable misfit. However, this review demonstrated that the mechanical response to misfit is more critical than the biological response.

Undergraduate dental students' perspective of online learning and their physical and mental health during COVID-19 pandemic.

BACKGROUND AND OBJECTIVE: COVID-19 pandemic continuously spread exacerbating global concerns. It had impacted all life aspects such as social, cultural, economic and education. This study assess the impact of COVID-19 pandemic on undergraduate dental students at Faculty of Dentistry, University of Malaya. The objective of this study is to evaluate the impact of the pandemic on physical and mental health of undergraduate dental students. METHODS: This is a cross-sectional study. An online questionnaire was administrated to 150 undergraduate dental students. The questionnaire included questions related to students' demographic data, their concerns on academic achievement, their opinion on institution response, and the impact of the crisis on their mental and physical health. SPSS software v26.0 was used to analyse the collected data. RESULTS: A total of 147 respondents participated in the study. About 66% of the students felt comfortable in adapting to the new technology while 85.7% were concerned about the quality of online learning. Almost all students 98.6% expressed their doubts on the ability to pass the competency exams and to graduate on time, with only 49.7% agreed that clinical experience was effectively delivered through online classes. Most students were also concerned on the impact of the pandemic on their physical and emotional health 85.8% and 76.9% respectively. CONCLUSIONS: The findings of our study highlight the positive adaptation of the students to online learning and using technology. On the other hand, the study indicates that the COVID-19 pandemic brings negative impacts on our students' physical and mental health.

First steps of a digital workflow to build up a virtual articulator using open-source Autodesk Meshmixer software.

Virtual planning has become part and parcel of digital dentistry to ensure more precise planning, better treatment outcomes, and more effective communication between dental practitioners, dental technicians, and patients. In dentistry, CAD software programs are one way to achieve virtual treatment planning. Among the most crucial and critical steps in treatment planning and execution are virtual articulation and occlusal analysis of the maxillary and mandibular arches. These steps have a great influence on the success of the final outcome. The present article proposes a detailed method for constructing a novel virtual articulator that can also be used for educational purposes to enable occlusal analysis and adjustment for a virtual tooth mock-up by simulating a virtual dynamic occlusion through the use of open-source Autodesk Meshmixer software.

Clustered Regularly Interspaced Short Palindromic Repeats System of Genome Engineering in Embryos to Repair Genes.

CRISPR is a powerful gene editing tool for correcting disease-causing mutations. It is becoming more and more evident that CRISPR is a promising approach to treating human genetic diseases. The technologies for adding or removing genes have made significant advances over the past few years and have shown promising potential outcomes. In the current study, we mainly introduce the CRISPR/Cas system and there are several applications in the treatment of genetic diseases, particularly during embryo development.

Deviation of dental implants placed using a novel 3D-printed surgical guide: An in vitro study.

BACKGROUND: There is very little literature available on the reliability of the rapid prototyping technology in the production of three-dimension (3D)-printed surgical guides for accurate implant placement. OBJECTIVES: The aim of the study was to evaluate the deviation of implant placement performed with a surgical guide fabricated by means of the rapid prototyping technique (the PolyJet™ technology). MATERIAL AND METHODS: Twenty sheep mandibles were used in the study. Pre-surgical cone-beam computed tomography (CBCT) scans were acquired for the mandibles by using the Kodak 9000 3D cone-beam system. Two implants with dimensions of 4 mm in diameter and 10 mm in length were virtually planned on the 3D models of each mandible by using the Mimics software, v. 16.0. Twenty surgical guides were designed and printed using the PolyJet technology. A total of 40 implants were placed using the surgical guides, 1 on each side of the mandible (2 implants per mandible). The post-surgical CBCT scans of the mandibles were performed and superimposed on the pre-surgical CBCT scans. The amount of deviation between the virtually planned placement and the actual implant placement was measured, and a descriptive analysis was done. RESULTS: The results showed that the mean deviation at the implant coronal position was 1.82 ±0.74 mm, the mean deviation at the implant apex was 1.54 ±0.88 mm, the mean depth deviation was 0.44 ±0.32 mm, and the mean angular deviation was 3.01 ±1.98°. CONCLUSIONS: The deviation of dental implant placement performed with a 3D-printed surgical guide (the PolyJet technology) is within the acceptable 2-millimeter limit reported in the literature.