Background: An ever-increasing demand is seen for clear aligners and transparent vacuum-formed retainers. They are esthetic and convenient. However, the biomaterials used in these appliances might pose biological safety and biocompatibility threats in terms of their bisphenol-A (BPA) release, cytotoxicity, adverse effects, and estrogenic effects. Due to the controversial results and the lack of any systematic reviews in this regard, we conducted this systematic review. Materials and Methods: Web of Science, PubMed, Cochrane, Scopus, and Google Scholar as well as references of the found articles were searched (independently by 3 researchers) up to December 22, 2021, to find studies relevant to the biocompatibility of clear aligners and thermoplastic retainers. The search keywords were a combination of the following (and more): Essix, vacuum-formed aligner, thermoplastic aligner, clear aligner, Invisalign, vacuum-formed retainer, BPA release, monomer release, cytotoxicity, estrogenicity, biocompatibility, chemical properties, and oral epithelial cell. As eligibility criteria, articles in all languages would be included as long as their text could be translated clearly using online translators or by professional translators; all types of publications (article, book, and thesis) would be included if containing relevant studies and information; they should have been on clear liners or thermoplastic retainers; and they should have been on biocompatibility, safety, cytotoxicity, or estrogenicity of clear aligners or thermoplastic retainers. There were no restrictions on the type of study (randomized clinical trials, experimental in vitro studies). Studies focusing merely on the mechanical properties of clear aligners or thermoplastic retainers (without examining their chemical properties) would be excluded. The risk of bias was assessed. Results: The risk of bias was rather low. However, the methodologies of the studies were quite different. Overall, 16 articles (1 randomized clinical trial and 15 in vitro studies) were identified. The data for BPA release were reported in four articles (1 clinical trial and 3 in vitro studies). Quantitatively speaking, the amount of released BPA reported by in vitro studies was very low, if not zero. However, the BPA level was very high in the only randomized clinical trial. Many adverse effects were linked to using clear aligners or transparent retainers, including pain and soft-tissue issues such as burning, tingling, sore tongue, lip swelling, blisters, ulceration, dry mouth, periodontal problems, and even systemic problems such as difficulty in breathing. Besides these biological adverse effects, oral dysfunctions and speech difficulties and tooth damage may be associated with clear aligners and should as well be taken into consideration. Conclusion: Given the very high levels of BPA leach observed in the only clinical trial and considering other possible dangers of small traces of BPA (even at low doses) and also given the numerous adverse events linked to clear aligners or transparent retainers, it seems that safety of these appliances might be questionable and more clinical studies of biocompatibility are needed in this regard.

Background: Different studies about the effects of mouthwashes on force reduction by elastomeric chains are reported in the literature. Hence, this review was done for the assessment of force degradation in the elastomeric chains in different mouthwash compositions. This study helps to improve the clinical performance of elastomeric chains used in orthodontics, reducing force degradation, and finally assisting clinicians in choosing better and more efficient methods for their treatments. Materials and Methods: In this review article, an extensive search was performed in the electronic databases of Cochrane Library, Web of Science, PubMed, and Scopus from the year 1990–2020. No language restriction was considered and manually investigated the reference lists of all articles related to the title. Out of 450 obtained articles, 14 in vitro studies were chosen based on the inclusion criteria, and their quality was assessed using modified CONSORT. This systematic review was limited and written based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Results: Based on the results achieved, mouthwashes containing alcohol caused considerable force degradation in the elastomeric chains compared to the alcohol-free ones and mouthwashes with fluoride caused lesser force degradation compared to other types.

Background: The burden of oral diseases is increasing, which constitute a major public health problem. The use of probiotics as an adjuvant, along with routine dental care practice by an individual, can produce additional benefits in the maintenance of one's oral health. The study aimed to investigate the effect of Bifidobacterium as a probiotic on oral health. Material and Methods: Six databases and registers were searched from the start of the database to December 2021 without any restrictions. Randomized controlled trials (RCTs) evaluating the clinical effects of Bifidobacterium as a probiotic on oral health were included in the study. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed to conduct this systematic review. The included studies were analyzed for the risk of bias using the Cochrane risk-of-bias tool for randomized trial (RoB 2) tool as well as quality of available evidence using GRADE criteria. Results: From the 22 qualified studies, four studies showed non-significant results. There was a high risk of bias in 13 studies and some concerns of bias in nine studies. No adverse effects were reported, and the quality of available evidence was moderate. Conclusion: The effect of Bifidobacterium on oral health is questionable. Further high-quality RCTs are required on the clinical effects of bifidobacteria and also the optimum level of probiotic needed, and ideal mode of administration to provide oral health benefits. Furthermore, synergistic effects of the combined use of various strains of probiotics need to be studied.

Background: Dentistry practice has become more complex and challenging in the recent years. The clinical decision-making process has experienced many problems due to changing socioeconomic patterns, knowledgeable patients, rapid technological advances, and information explosion. The present study reviewed the status of the attitude toward evidence-based dentistry (EBD) among dental students of Iran Universities. The effect of the educational intervention was also assessed. Materials and Methods: This systematic review was conducted according to the Preferred Reporting Items for Systematic review and Meta-Analysis checklist. Search strategy was developed by Medical Subject Headings terms and keywords surfing electronic available databases including Medline/PubMed and Google Scholar and local databases such as Scientific Information Database (SID) and Magiran. Two reviewers read the abstracts of all eligible papers and excluded the duplicates. They extracted the information of the full-text of the studies included in the review and assessed the quality by Joanna Briggs Institute critical appraisal checklist. Results: Ten studies including 8 cross-sectional and 2 interventional studies met the criteria. The assessment of the attitude of 937 dental students from a different region of the country toward EBD showed moderate to acceptable status using 3 different tools. In regard to educational interventions, 2 studies were successful to improve their attitude. Conclusion: Although the researchers presented good scores on the attitude questionnaires, the quality of the study tools, the eligible criteria for recruiting the participants and the method of evaluating the construct of attitude should be investigated in future studies.

Background: During the orthodontic bonding process, the need for repositioning or rebonding of orthodontic brackets on the enamel surface occurs frequently. The aim of this study is to compare the shear bond strength (SBS) in rebonding orthodontic stainless steel brackets with three different methods of enamel surface conditioning methods. Materials and Methods: In this in vitro study, 80 human premolars that were extracted for orthodontic purposes were randomly divided into four groups and underwent orthodontic bonding procedure (N = 20). Except for the control group, three other groups underwent debonding and rebonding process in which after removing the remaining adhesive with tungsten-carbide bur, enamel surface conditioned by three different methods including re-etching with phosphoric acid, sandblasting + acid etching, and Erbium-doped Yttrium–Aluminum–Garnet laser. Then, the SBS of the bracket to the enamel surface was compared between different groups. Scanning Electron microscopy images were also obtained from a number of samples. Statistical analysis was performed by Kruskal–Wallis and Mann–Whitney tests. Results: The highest SBS was observed in the primary bond (control group) with an average of 29,440 MPa. There was a significant difference between the studied groups (P < 0.001) and only the group that was re-etched with phosphoric acid had no significant difference with the control group (P = 0.708) ∝ =0.05. Conclusion: Rebonding of brackets using phosphoric acid for reconditioning of the enamel surface creates bond strength comparable to the primary bond. Other groups had significantly lower SBS than the control group.

Background: Periodontitis, the second most common reason for tooth loss in adults, is a chronic inflammatory condition that increases the prevalence of cancer by inhibiting apoptosis and promoting tumor cell growth. However, it is still debatable if tooth loss is an important risk factor in oral cancer (OC). The aim of this systematic review is to analyze the relationship between tooth loss and the probability of developing head-and-neck cancer and also to see if there is an association between tooth loss, periodontitis, and the risk of OC. Materials and Methods: Studies that depicted a link between tooth loss and OC (till 2017) were searched from online databases accompanied by a thorough manual search of relevant journals. Data were collected from eligible studies, and meta-analysis was carried out using the Meta-Analysis software. The effect of various inclusions was assessed by sensitivity and subgroup analysis. Publication bias was also evaluated. Results: The meta-analysis consisted of 15 publications. When the number of teeth lost was counted, there was significant variability (I2 = 98.7%, P = 0.0001). When more than 15 teeth were missing in a subgroup analysis, there was a 2.4 times greater risk of OC (odds ratio: 2.496, 95% confidence interval [CI] = 2.067–3.015, P = 0.001) with no heterogeneity (I2 = 0.00%, 95% CI for I2 = 0.00–68.98). Subgroup analysis revealed that there was no evidence of publication bias. Conclusion: It was concluded that tooth loss can increase the OC risk by nearly 2 folds. However, large-scale population-based studies are needed to substantiate the findings.

The corona virus malady 2019 (COVID-19) pandemic has rekindled the well established argument regarding the role of dental aerosol in transference of severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). Aerosols and droplets are generated amid innumerable dental procedures. With the commencement of the COVID-19 pandemic droplet, a review of the infection/disease control strategies for aerosols is required. We do not know where this pandemic is directed. We do not have conclusive evidence for an optimal management strategy. Every day brings in varying information, so recognizing the hazard created by aerosols will help diminish the probability of infection transfer at the time of dental procedures. Hence, the author assessed the evidence-based medical and dental literature in relation to “aerosol' that documented the source of transmission of aerosol through various potential routes, addressed the risk potential to patients and the dental team, and assessed the additional measures that might minimize the viral transmission if regularly adopted. In this article, the author evaluated and compiled dental guidelines by various countries and various health-care associations in context to aerosol-generating procedures and has made recommendations for the restriction of dental aerosols and splatter in routine dental practice.

Background: To consciously select an appropriate dental cement for each type of intracanal post. Materials and Methods: An electronic search was carried out (1970 to 2020) through Medline, PubMed, Scopus, and Google Scholar. The following keywords were searched in title, abstract, or keywords with different combinations: endodontically treated tooth, root canal therapy, dental posts, post and core, prefabricated posts, custom posts, dental cement, resin cements, cement selection, cement, and adhesive resin cement. Results: Evaluating full texts, 146 articles were selected to review the types of posts and cements, selection criteria of appropriate cement for each type of post, and compare the results obtained by different cements. Conclusion: Dental cements affect the survival rate, durability, and success rate of postbased treatments. Considering special characteristics and application of each type of intracanal post, conscious selection of cement is an important determining factor in long-lasting success. Choosing an appropriate cement has a key role in success and durability of dowel posts-based fixed restorations.

The most common orthognathic surgery approach consists of three steps: presurgical orthodontic treatment, surgery, and postsurgical orthodontic treatment. Despite its advantages, this technique has some disadvantages, too, including a long treatment period, problems in mastication and articulation, temporary worsening of the patient's appearance, and psychological problems for the patient. The introduction of the surgery-first orthognathic approach has been an attempt to overcome these problems. In this article, we wish to provide a comprehensive overview on this approach. In this approach, which consists of surgery without orthodontic preparation and a short period of orthodontic treatment after it, the overall duration of treatment decreases and the patient's appearance improves. The skeletal anchorage, placed at the time of surgery, can be used to facilitate tooth movements after surgery. Despite the advantages of this technique, it is associated with some limitations; in particular, occlusion cannot have a guiding role during surgery. Therefore, correct diagnosis, prediction of the outcomes, and simulating correction with the model setup are of crucial importance. The surgeon's knowledge and expertise have a significant role in this respect.

Background: Since the symptoms of child abuse and neglect often manifest in the orofacial region, the dental team has a key role in identifying children subjected to abuse. This study was aimed to explore the prevalence of failure to take history as a barrier to reporting child abuse by dentist around the world. Materials and Methods: In this systematic review and meta-analysis, PubMed, Embase, Scopus, Google Scholar, ProQuest, Cochrane, and ISI databases were searched for the cross-sectional articles in English languages on barriers to reporting child abuse and lack of knowledge about referral procedures by dentists since 1985 using Medical Subject Headings (MeSH). The full-texts of all included articles were obtained and assessed for quality according to Newcastle–Ottawa Scale adapted for cross-sectional studies. The qualified articles were then studied thoroughly and results were extracted. Data were analyzed by Comprehensive Meta-Analysis software using meta-analysis and random effects model. Heterogeneity was determined by Q-test and I-square index. Results: A total of 17 articles were included in the meta-analysis. The prevalence of lack of knowledge about referral procedures as a barrier was determined according to the meta-analysis of the number of relevant articles and was (55%, confidence interval: 0.48, 0.62). Conclusion: The analysis of various studies revealed lack of information about referral procedures as an important barrier to report child abuse by dentists.

The current global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its associated coronavirus disease (COVID-19), has grasped the attention of entire international community and has caused widespread public health concerns. All the efforts taken globally to curtail the novel COVID-19; the outbreak is still on a rise owing to the community spread pattern of this infection. COVID-19 is a zoonotic infection that, like other coronavirus infections, is believed to have been originated in bats and pangolins, and later transmitted to humans. Once in the human body, this coronavirus (SARS-CoV-2) is abundantly present in nasopharyngeal and salivary secretions of affected patients and its spread is predominantly thought to be respiratory droplet in nature. Dental professionals may soon encounter patients with suspected or confirmed SARS-CoV-2 infection and will have to act carefully not only to provide care but at the same time prevent spread of infection. Thus, the aim of this article is to provide a brief overview of the epidemiology, symptoms and routes of spread of the novel COVID-19 infection. In addition to this, specific recommendations for dental practice are prescribed for patient screening, infection control strategies, and patient management protocol.

Intraoral ancient schwannoma is a rare type of oral schwannoma, which is encapsulated and well demarcated from the surrounding tissues. Ancient schwannomas are associated with conventional features of neurilemmoma; however, they are distinguished from other types of schwannoma due to factors such as the long history, cellular architecture showing hypocellularity, and hyalinized matrices. This systematic review was performed through searching in databases such as PubMed and Google Scholar using related keywords (intraoral, oral, ancient, schwannoma, and neurilemmoma). Eventually, 26 case reports were systematically reviewed by the researchers. Required data were extracted by one researcher, and all the selected articles were reviewed in full text after screening. This systematic review aimed to determine the most significant influential factors in intraoral ancient schwannoma and evaluate the diagnostic and therapeutic methods in this regard.

Background: The high prevalence of malocclusion is a public health problem in the world and the third priority in oral care. Numerous primary studies have presented reports on the prevalence of malocclusion among Iranian children. In combination, the results of these studies using meta-analysis are highly valuable for health policy-making. Similarly, this study aimed at determining the prevalence of different types of malocclusion among Iranian children. Materials and Methods: Using relevant keywords, national and international databases were explored. After narrowing down the search strategy and leaving out the duplicates, the remaining articles were screened based on titles and abstracts. To increase search sensitivity, reference lists of the papers were examined. To identify unpublished articles and documentations, a set of negotiations were done with the people involved and research centers. Finally, the heterogeneity index between the studies was determined using Cochran (Q) and I² tests. According to the results of heterogeneity, the random effects model was used to estimate the prevalence of malocclusion in Iran. Results: In total, 25 articles were included in the meta-analysis process. The prevalence of dental malocclusion was estimated in 28,693 Iranian children aged 3-18 years. The total prevalence of Class I, II, and III malocclusion was 54.6% (46.5-62.7), 24.7% (20.8-28.7), and 6.01% (4-7.1), respectively. The prevalence of Class I, II, and III malocclusion was 44.6% (32.9-56.2), 21.5% (18.01-25.1), and 4.5% (3.2-5.9) in boys and 48.8% (36.8-60.8), 21.5% (16.9-25.1), and 5.5% (3.9-7.1) in girls, respectively. Conclusion: This study showed a high prevalence of malocclusion among Iranian children. Also, the results indicated that the prevalence is higher in girls.

Root canal therapy has enabled us to save numerous teeth over the years. The most desired outcome of endodontic treatment would be when diseased or nonvital pulp is replaced with healthy pulp tissue that would revitalize the teeth through regenerative endodontics. 'A search was conducted using the Pubmed and MEDLINE databases for articles with the criteria 'Platelet rich plasma', 'Platelet rich fibrin', 'Stem cells', 'Natural and artificial scaffolds' from 1982-2015'. Tissues are organized as three-dimensional structures, and appropriate scaffolding is necessary to provide a spatially correct position of cell location and regulate differentiation, proliferation, or metabolism of the stem cells. Extracellular matrix molecules control the differentiation of stem cells, and an appropriate scaffold might selectively bind and localize cells, contain growth factors, and undergo biodegradation over time. Different scaffolds facilitate the regeneration of different tissues. To ensure a successful regenerative procedure, it is essential to have a thorough and precise knowledge about the suitable scaffold for the required tissue. This article gives a review on the different scaffolds providing an insight into the new developmental approaches on the horizon.

Vital pulp therapy (VPT) is a biologic and conservative treatment modality to preserve the vitality and function of the coronal or remaining radicular pulp tissue in vital permanent teeth. A search was conducted via the Cochrane database, PubMed, MEDLINE, and Ovid for any articles with the criteria for "pulp-capping," or "pulp-capping materials" and "VPT outcomes" from 1978 to mid 2014. All articles were evaluated and the valid papers were selected. The outcomes of various VPT techniques, including indirect pulp treatment, direct pulp treatment, partial pulpotomy, and complete pulpotomy in vital permanent teeth were extracted. Although various studies have different research approach, most studies noted a favorable treatment outcome. Mineral trioxide aggregate (MTA) appears to be more effective than calcium hydroxide (Ca(OH) ₂ ) for maintaining long-term pulp vitality after indirect and direct pulp-capping. However, it seems that the success rate for partial pulpotomy and pulpotomy with Ca(OH) ₂ is similar to MTA.

Glutathione, considered to be the master antioxidant (AO), is the most-important redox regulator that controls inflammatory processes, and thus damage to the periodontium. Periodontitis patients have reduced total AO capacity in whole saliva, and lower concentrations of reduced glutathione (GSH) in serum and gingival crevicular fluid, and periodontal therapy restores the redox balance. Therapeutic considerations for the adjunctive use of glutathione in management of periodontitis, in limiting the tissue damage associated with oxidative stress, and enhancing wound healing cannot be underestimated, but need to be evaluated further through multi-centered randomized controlled trials.

The purpose of this review is to have an overview on the applications on the autologous fibrin glue as a bone graft substitute in maxillofacial injuries and defects. A search was conducted using the databases such as Medline or PubMed and Google Scholar for articles from 1985 to 2016. The criteria were “Autograft,” “Fibrin tissue adhesive,” “Tissue engineering,” “Maxillofacial injury,” and “Regenerative medicine.” Bone tissue engineering is a new promising approach for bone defect reconstruction. In this technique, cells are combined with three-dimensional scaffolds to provide a tissue-like structure to replace lost parts of the tissue. Fibrin as a natural scaffold, because of its biocompatibility and biodegradability, and the initial stability of the grafted stem cells is introduced as an excellent scaffold for tissue engineering. It promotes cell migration, proliferation, and matrix making through acceleration in angiogenesis. Growth factors in fibrin glue can stimulate and promote tissue repair. Autologous fibrin scaffolds are excellent candidates for tissue engineering so that they can be produced faster, cheaper, and in larger quantities. In addition, they are easy to use and the probability of viral or prion transmission may be decreased. Therefore, autologous fibrin glue appears to be promising scaffold in regenerative maxillofacial surgery.