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Abstract Objectives The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) virus causes coronavirus disease 2019 (COVID‐19), a respiratory infection that has spread worldwide and is responsible for a high death toll. Although respiratory symptoms are the most common, there is growing evidence that oral signs of COVID‐19 can also be seen in children. The purpose of this systematic review is to provide a comprehensive analysis of the available data on the oral manifestations of COVID‐19 in children and to recommend appropriate methods of diagnosis and treatment. Methods A systematic search of the MEDLINE, EMBASE, Scopus, and Web of Science databases was done to discover relevant papers published between their establishment and January 2023. Articles detailing oral symptoms in pediatric patients with confirmed COVID‐19 infection were included, and data on clinical characteristics, diagnosis, treatment, and outcomes were extracted and evaluated. Results A total of 24 studies involving 2112 pediatric patients with COVID‐19 were included in the review. The most common presentations are oral lesions, taste and smell disorders, oral candidiasis, hemorrhagic crust, tongue discoloration, lip and tongue fissuring, gingivitis, and salivary gland inflammation. These manifestations were sometimes associated with multi‐system inflammatory syndrome in children (MIS‐C) or Kawasaki disease (KD). Management strategies varied depending on the severity of the oral manifestation and ranged from symptomatic relief with topical analgesics to systemic medications. Conclusion Oral symptoms of COVID‐19 are relatively prevalent in juvenile patients and can be accompanied by severe systemic diseases, such as MIS‐C or Kawasaki illness. Early detection and adequate care of these oral symptoms are critical for the best patient results. Understanding the underlying pathophysiology and developing targeted treatments requires more investigation.

Statement of the Problem: Considering the relatively high prevalence of oral mucosal ulcers, their fast healing is of significance. Purpose: This study aimed to histopathologically compare the effects of 810 nm and 940 nm diode laser on the healing of iatrogenic oral ulcers in rabbits. Materials and Method: In this single-blind experimental study, mucosal ulcers measuring 3mm in diameter and 1mm in depth were bilaterally created in the buccal mucosa of 18 rabbits using a biopsy punch. The defects were irradiated with 810 nm diode laser on the right side and 940 nm diode laser on the left side. Biopsy samples of the same depth were obtained from the ulcers on days 3 and 7 followed by histopathological analysis. The intensity of inflammation was determined on hematoxylin-eosin-stained sections using a four-point scale. Data were analyzed employing the Wilcoxon signed rank test. Results: The degree of inflammation was not significantly different between the 810nm and 940nm diode laser groups on day 3; but on day 7, animals receiving 810 nm experienced a significantly lower degree of inflammation compared to those treated with 940 nm laser (p= 0.028). Conclusion: When comparing 810- and 940-nm diode lasers, 810 nm irradiation significantly decreased the severity of inflammation in oral wounds created on the buccal mucosa of rabbits in a time-dependent manner.

In the article entitled "Effect of amitriptyline on orthodontic tooth movement in rats: an experimental study" which appeared in J Dent Res Dent Clin Dent Prospect 2020;14(3): 147- 152, doi: 10.34172/joddd.2020.033, the name of the fourth author has been misspelled. The correct spelling is Shahroo Etemad-Moghadam. The original version of the article has been updated to reflect the corrections.

Background: The aim of this study was to compare conventional and microwave-assisted decalcification of sheep bone with and without teeth and to detect any difference in tissue detail preservation, staining quality, and rate of decalcification. Materials and Methods: In this method analysis study, twenty-four specimens consisting of 12 blocks of mandibular molars with their surrounding bone and 12 blocks of mandibular osseous tissue were allocated into two microwave or routine decalcification groups using 5% nitric or formic acid as decalcifying agents. In addition to decalcification rate, a number of variables were used to assess staining quality and tissue detail preservation which were compared between the two groups using Mann–Whitney test (P < 0.05). Results: Time to complete decalcification was significantly reduced in the microwave-treated samples as compared to the conventional method, regardless of the decalcifying agent (P = 0.025). For both acids, most variables related to staining quality and tissue detail preservation were similar between the techniques (P > 0.05). Patchy staining in bone samples and tissue tears in bone + teeth specimens were more common in the routine method when using nitric acid (NAc) (P = 0.046) and formic acid (FAc) (P = 0.046), respectively. In comparing acids, the performance of FAc was slightly inferior to that of NAc, especially for specimens containing both tooth and bone. Conclusion: The use of microwave technology can accelerate decalcification of bone and teeth of sheep mandibles and at the same time preserve tissue structure and staining quality. Further studies are required to help select the best demineralizing agent, especially in specimens containing bone and teeth.

The pathogenic mechanism of SARS-CoV-2 infection is unclear, and its symptoms vary in different patients. Initial reports of COVID-19 concentrated on pulmonary issues, but with time, additional features such as hyposmia/anosmia, dysgeusia, and skin lesions were added to the list of COVID-19 symptoms. There have been an increasing number of reports on oral cavity lesions in individuals with COVID-19, which might be relevant considering that this location is one of the first sites coming into contact with the virus and that it contains the SARS-CoV-2 receptor. We hereby aim to familiarize practicing head and neck clinicians with the range of oral lesions reported in COVID-19 patients and to critically appraise the most recent data on the role of SARS-CoV-2 in these lesions. We also discuss the ongoing debate on the direct/indirect association of oral symptoms with the disease. COVID-19 cases with simultaneous oral symptoms were extracted from the literature, and articles discussing the role of SARS-CoV-2 in oral lesions were compiled and methodically analyzed. We found approximately 95 COVID-19 patients with a wide range of oral lesions. Based on current evidence, the exact role of SARS-CoV-2 in the development of oral lesions remains unclear. Oral examination of patients is needed to provide adequate cases for analysis to clarify unknown problems related to COVID-19. There is evidence to support both the direct and indirect roles of SARS-CoV-2 in the development of oral lesions. Awareness of the possibility of oral manifestations in COVID-19 is important to clarify the range of disease signs and symptoms.

Background: A number of factors may be responsible for the differences in the biologic behaviors of oral and lower lip squamous cell carcinomas (SCCs). Immunohistochemical invasion profiles have been used to detect invasion patterns like epithelial-mesenchymal-transition (EMT) and collective-cell-invasion (CCI), which have not been investigated in lower lip neoplasms. The aim of the present study was to compare the invasive phenotypes of SCCs of the lower lip and oral cavity. Method: A total of 44 OSCCs and 37 lower lip SCCs were immunostained with E-Cadherin, N-Cadherin, and podoplanin. Based on their expression patterns, tumors were allocated to EMT, CCI or non-EMT/non-CCI categories. Results: None of the oral SCCs showed EMT; while 5 lower lip SCCs demonstrated this phenotype. CCI was observed in 12 oral SCCs and 4 lower lip SCCs. The third group included 32 and 28 cases of oral and lower lip tumors, respectively. A significant difference in invasive phenotype was found between the two locations (P = 0.009). Conclusion: Oral cavity and lip tumors differ in various aspects and according to our results; the pattern of invasion may be added to these features. Between the two major invasion patterns, EMT was more prevalent in lip tumors while CCI was observed more commonly in oral neoplasms. The significance of the different expression patterns of the non-EMT/non-CCI category requires further investigation.

Induction of premalignant lesions in animal models is of high value for research purposes. This study aimed to induce dysplasia in hamster mucosal pouch for investigation of dysplastic lesions using dimethylbenz(a)anthracene. The buccal pouch of 10 hamsters was painted with dimethylbenz(a)anthracene for 10 weeks every other day. At 5 and 10 weeks, they underwent histopathological analysis. Clinically, there was no change until week 7; after which mucosal thickening occurred. Hamsters scarified at 5 weeks and 10 weeks demonstrated mild and moderate dysplasia, respectively. dimethylbenz(a)anthracene is a useful tool for inducing dysplastic lesions in the buccal pouch mucosa of hamsters.

Background: Expression of various cellular/molecular factors change during the course of tumor formation from odontogenic tissues of the tooth germ. Evaluation of these factors can help provide a better perception of the tumorigenesis and biologic behavior of odontogenic tumors (OTs). Syndecan-1 is a heparan sulfate proteoglycan which has not been extensively investigated in these lesions. The objective of the present study was to assess the immunohistochemical expression of CD138 in adenomatoid odontogenic tumor (AOT), ameloblastic fibroma (AF) and odontogenic myxoma (OM) and to compare it with ameloblastoma and keratocystic odontogenic tumor (KCOT). Method: A total of 58 OTs consisting of 7 AOTs, 5 OMs, 7 AFs, 29 KCOTs and 10 ameloblastomas were immunohistochemically stained with monoclonal antibody against syndecan-1 and the percentage and intensity of the immunostained cells was assessed. Kruskal–Wallis test followed by Bonferroni analysis was used for comparisons (P

Background and Aim: Captopril is an oral angiotensin-converting-enzyme (ACE) inhibitor extensively used in the treatment of hypertension and heart failure. ACE has been suggested to function in bone cells and might therefore impact orthodontic tooth movement (OTM). Considering the controversy surrounding the effects of ACE and its inhibitors on osseous tissues, we aimed to evaluate the effect of captopril on OTM for the first time in a rat model. Materials and Methods: Orthodontic appliances were fixed between the left first molars and incisors of 30 rats divided into three groups (n=10) receiving captopril, saline or no treatment. Following sacrifice on day 21, the amount of tooth movement was measured as the distance created between the first and second molars. Bone density was assessed by lateral cephalograms on days 1 and 21 and osteoclast number, root resorption and periodontal ligament (PDL) width were analyzed histologically. One-way ANOVA followed by post-hoc test were used for statistical analysis (P

Objectives: Nitric oxide (NO) is a signaling molecule that mediates mechanical bone loading. Cyclic guanosine 3', 5' monophosphate (cGMP) is a NO-induced effector molecule. The aim of this study was to assess the effect of NO-cGMP pathway on orthodontic tooth movement (OTM) in rats by use of two phosphodiesterase 5 (PDE5) inhibitors namely sildenafil and tadalafil as chemical tools. Materials and Methods: Forty-five male Wistar rats were divided into three equal groups (n=15) based on the substance they received. The first group received daily injections of tadalafil; the second group received daily injections of sildenafil and the third group received daily injections of normal saline. The orthodontic appliances consisted of nickel-titanium closed-coil spring ligated between the maxillary right incisor and the first molar of the animals for 21 days. The amount of tooth movement was measured in all three groups at the end of this period. Histological analysis was performed to assess root resorption lacunae, osteoclast number and periodontal ligament (PDL) thickness. Results: All appliance-treated molars in the experimental and control groups showed evidence of tooth movement. The mean OTM was calculated to be 0.39±0.16, 0.32±0.16 and 0.26±0.16mm in tadalafil, sildenafil and control groups, respectively and there were no significant differences in OTM among the study groups (P>0.05). In the tadalafil group, significantly greater root resorption on the tension side was seen when compared with controls (P≤0.05). Conclusions: Tadalafil and sildenafil PDE-5 inhibitors affecting the NO-cGMP pathway did not affect OTM in rats.

Objectives: The aim of this study was to histologically compare the regenerative properties of two allografts manufactured by two Iranian companies. Materials and Methods: In this study, four 8-mm defects were produced in the calvaria of 12 rabbits. In three defects, three types of allografts namely ITB, CenoBone and Grafton were placed and one defect served as control. Samples were prepared and histomorphometric evaluations were carried out after healing periods of four weeks (interval 1) and eight weeks (interval 2). Qualitative and quantities variables were compared and analyzed with SPSS software. Results: Mild inflammation was observed in 45% and 12.5% of the samples in the first and second intervals, respectively. Foreign body reaction was observed in only 5% of the samples. The quality of regenerated bone was immature, mixed and lamellar in 54.5%, 15.9% and 4.5% of the samples, respectively. The rate of allograft resorption was the highest and lowest in the CenoBone and Grafton samples, respectively. The mean amount of regenerated bone was higher in areas containing Grafton; however, the differences were not statistically significant. Conclusion: Despite the differences in the numerical values of bone regeneration, there were no statistically significant differences in bone generation among the material groups, and allografts manufactured in Iran can be suitable alternatives to Grafton with the same good properties. Further studies are necessary to clarify the efficacy of these allografts.

Statins are used as cholesterol-lowering drugs by many patients and have been recently shown to affect bone metabolism. The aim of this study was to determine the effect of atorvastatinon on orthodontic tooth movement (OTM) in rats.Thirty-six adult male Sprague-Dawley rats were randomly divided into three groups of 12 samples each. Group A, served as control with no medication while groups B and C received a daily gavage of carboxymethyl cellulose (CMC) as vehicle and atorvastatin (5 mg/kg) as test substance, respectively. In all three groups, 6mm nickel-titanium closed-coil springs were ligated between the maxillary incisors and first left molars to deliver an initial force of 60g. Tooth movement was measured following sacrifice, 21 days after appliance insertion. Root resorption, PDL width and osteoclast number were histologically evaluated and compared between the groups.The mean amount of tooth movement was 0.62 mm in group A, 0.59 mm in group B and 0.38 mm in group C. OTM reduction following administration of atorvastatin was statistically significant (p0.05).According to the results obtained in the current study, atorvastatin appears to reduce tooth movement in rats; however its effect on osteoclasts, especially osteoclastic function, requires further investigation.