مجله دانشکده دندانپزشکی مشهد
سال چهل و پنجم شماره 1 (پیاپی 116، بهار 1400)

The accurate impression of the mouth and reproduction of gingiva can be regarded as a record for the production of a cast with optimum fitting and dental restoration. This study investigated the soft tissue accuracy around implant through digital and conventional methods with different viscosities of additional silicone.

An acrylic dentifrice was utilized in the upper right central edentulous area in this study. Moreover, a bone level analogous fixture with a diameter length of 12 and 4.1 mm was inserted in the edentulous area 3 mm below the gingiva parallel to the adjacent central tooth. In total, 30 impressions were made using dentifrice with the help of digital scans (6 times), conventional impressions using a custom tray and regular body additional silicone (12 times), and conventional impressions by a stock tray with putty wash silicone (12 times). Moreover, 6 casts with and 6 casts without gingival masks were prepared using the conventional method before the cast preparation. They were then scanned using the Lab scanner in the STL format. Following that, superimposition of the data and cloud compare software were utilized to compare and evaluate the changes of soft tissue around the implant in each method considering the reference method. The differences between the proposed models and the reference model were recorded, and the data were analyzed in this study.

The result of the Kruskal Wallis indicated no significant differences among the groups in terms of the mean values of the data (p < /em>=0.345).

Regarding the mismatch among the impression methods, the results showed no significant difference in this regard.

Lichen planus is a relatively common chronic inflammatory autoimmune disease of unknown etiology. The World Health Organization has identified lichen planus as a potential precancerous lesion. Cyclooxygenase-2 (COX-2) is a key enzyme for inflammatory processes and cell proliferation. The increased expression of COX-2 in some chronic precancerous inflammatory diseases and malignant neoplasms of the upper aerodigestive tract suggests its role in the early stages of carcinogenesis of the head and neck and can show its potential as a prognostic factor and marker of altered behavior. The aim of this study was to analyze the COX-2 marker in the pathogenesis and biological behavior of oral lichen planus and oral lichen planus with dysplasia. The incidence rate of the COX-2 marker in the 50 samples of the pathology archive of Mashhad Dental School, Mashad, Iran, including 25 samples of oral lichen planus and 25 samples of oral lichen planus with dysplasia, was evaluated using immunohistochemistry in 2017. In this cross-sectional descriptive-analytical study, the Kruskal-Wallis and Chi-square statistical tests were used to compare the incidence of the COX-2 marker in the study groups. Based on the results of this study, there was no significant difference between the two groups of oral lichen planus and oral lichen planus with dysplasia in COX-2 staining pattern in the basal layer and connective tissue; however, it was significantly higher in the suprabasal layer of the lichen planus group with dysplasia than that of the oral lichen planus group. In terms of location, lichen planus lesions with dysplasia were more commonly observed in the buccal mucosa, and oral lichen planuslesions (without dysplasia) were more frequently noticed in lips. Based on the findings of the present study, it can be concluded that increased COX-2 expression is observed in oral lichen planus lesions, especially those with dysplasia. The presence of lesions in some areas of the mouth, such as the buccal mucosa, tongue, and border of the tongue, is also more associated with dysplasia.

Bruxism in children negatively affects the quality of life. The present study aimed to evaluate theprevalence of bruxism and its associated factors among 3-6-year-old children in Yazd in 2018. This cross-sectional (descriptive-analytical) study was conducted on 270 3-6-year-old children who were selected via cluster sampling in Yazd. The needed data were collected through parent questionnaire (demographic characteristics of child and parents, as well as child's medical history) and the children's assessment form (muscle examination, occlusion, temporomandibular joint (TMJ), and decayed, missing, and filled teeth (dmft)). The validity of the questionnaires was validated by experts' opinions, and the reliability of the questionnaires was confirmed rendering a Cronbach's alpha coefficient of 0.87. Data were analyzed in SPSS software. As evidenced by the obtained results, the prevalence of bruxism in 3-6-year-old children in Yazd was obtained at 46.7%. The relationship between bruxism in these children and gender was not significant, while the association between bruxism and age was significant (p < /em>=0.0001). There was no statistically significant relationship between parental education and bruxism in children; nonetheless, the relationship between parents' occupation and the prevalence of bruxism in children was significant. Children with bruxism have a family history of bruxism among their families. Furthermore, a statistically significant relationship was detected between bruxism and sleep talking, restless sleep, child dysthymia, prognosis, complaints of temporal pain, complaints of dental pain without signs of decay, type of occlusion, and limitation in mouth opening of children. Based on the results of the current study and the effect of such factors as parental occupation, sleep disorders, and dysthymia on the development of bruxism in children, it is necessary to increase parental knowledge through educational programs in an attempt to prevent and reduce the prevalence of bruxism in community.

The high success rate of implant treatments has made it one of the most common treatments in dentistry. Nevertheless, we are witnessing an increase in the side effects of implant treatments, such as esthetic problems. The present study aimed to evaluate the aesthetic indices (e.g., pink esthetic score (PES) and White Esthetic Score (WES)in dental implants delivered in the Implant Departmentof Mashhad Dentistry School in 2017-2019. The present study was conducted on 20 Patients with single implant in the anterior region of the maxilla whoseprosthetic work was completed in 2017. After cementing the crown, the photographs and casts of patients were prepared and evaluated for aesthetic indicators. The PES index included papillary mesial, papaldistal, gingival margin arch, gingival margin surface, bony prominence of root and color area, as well assoft tissue texture. The WES index encompassed tooth shape, color and surface texture, as well as translucency. The total score of each patient was calculated in the soft tissue and coronal sections. In the current study, 20 patients whoseimplant placement steps were performed in 2017 in the Implant Department of Mashhad DentalSchool were examined after reviewing the inclusion and exclusion criteria. Based on the results, the mean PES, WES, and the mean total PES/WES scores were obtained at 7.20±1.76, 6.75±2.04,and 13.95±3.41, respectively. In the PES index, five patients (25%) had unacceptable results. In theWES index, five patients (25%) had unacceptable results. Finally, a total of PES / WES scoresof five patients (25%) had unacceptable results. As evidenced by the findings of the present study, the results of PES and WES aesthetic indices in patients with a single implant were clinically acceptable.Nevertheless, there were still cases with low aesthetic score based on PES/WES criteria, highlighting the need for better care on the part of dentists for the attainment of more positive cosmetic results.

This study aimed to compare the knowledge, attitude, and practice of the technicians and their supervision of dental clinics in Mashhad.

In this study, the researchers examined 84 clinics and distributed the questionnaire among the technicians. The quality of the sterilization was evaluated by biological and chemical indicators and the results of the questionnaire. The biological and chemical indicators were placed inside the autoclave. The questionnaire investigated the incubation method, autoclave numbers, device performance monitoring method, indicator type, device temperature and pressure, and the number of times the device was turned on during the day, as well as the knowledge, attitude, and performance of the technicians. The collected data were analyzed in SPSS software (version 19).

Based on the findings, class B autoclaves were used in only 59% of the clinics. It was revealed that 7%, 26%, and 31% of the clinics applied biological testing, chemical testing, and physical methods to assess autoclave performance, respectively. The results of biological tests were positive in 20% of clinics, and 11.9% of chemical indicators did not show sufficient color change. It was also found out the knowledge, attitude, and performance scores were significantly higher in the dental technicians than those in the physician technicians.

According to the results of this study, it is recommended that the technicians of the dental department of public clinics be dentists as well. Public clinics should pay more attention to the quality of sterilization and infection control. The improvement of the technicians' knowledge will lead to better performance and consequently to an increase in the quality of sterilization and infection control.

Resistance of oral pathogenic bacteria to chlorhexidine mouthwash is increasing; therefore, researchers are looking for a replacement of chlorhexidine with suitable herbal mouthwash. This study aimed to investigate the antimicrobial effect of hydroalcoholic extract of Plantago major (a native strain of Khorasan, Iran) with and without zinc oxide nanoparticles on Streptococcus mutans.

In this in vitro study, the samples were tested in two groups of hydroalcoholic extract of Plantago major leaves with and without zinc oxide nanoparticles. To determine the minimum bactericidal concentration and minimal inhibitory concentration, agar diffusion and broth dilution methods were applied, respectively. A concentration of 500 ppm zinc oxide nanoparticles with a 0.4 nm diameter was used continuously in all stages of the experiment. The materials used in this study consisted of a standard strain of Streptococcus mutans (ATCC 25175), chlorhexidine 0.2% as a positive control, and distilled water as a negative control.

The mean diameter of the growth inhibition zone was obtained as 15±1 mm for the hydroalcoholic extract of Plantago major leaves with zinc oxide nanoparticles at a concentration of 1.56 mg/ml. The same extract at the same concentration, however without zinc oxide nanoparticles, showed the mean diameter of growth inhibition zone of 7.67±0.57 mm. The results of the t-test were indicative of a significant difference between the two groups (P-value<0.001).

In this study, the antimicrobial effect of Plantago major leaves extract with or without zinc oxide nanoparticles was well established. This research is peculiar since it revealed the effectiveness of low concentrations of this plant in killing Streptococcus mutans.

According to previous studies, heat shock protein 70 (HSP70) plays a role in the production of proinflammatory cytokines and inflammation. Given that no study has been performed in the field of dentistry in this regard, the present research aimed to identify the effect of HSP70 on moderate to severe generalized chronic periodontitis with the increase of mitogen-activated protein kinase (MAPK) and toll-like receptor 4 (TLR4) signaling pathways.

This pilot study was performed on 50 subjects with moderate to severe chronic generalized periodontitis and 50 subjects with healthy periodontitis who were candidates for crown lengthening (CL) surgery. The subjects were selected based on the inclusion criteria from the patients who referred to the Gingival Surgery Department in a Private Dental Center, Tabriz, Iran. Tissue samples were obtained from the patients during pocket depth reduction surgery (for the experimental group) and CL surgery (for the control group). Macrophage inflammatory cells were extracted from tissue samples and the cells were stimulated by HSP70 as a timer; subsequently, the level of TLR4 in macrophage cells was examined. Results of the study were reported using descriptive statistical methods, such as mean, standard deviation, and frequency percentage. Repeated measures analysis was used to compare the expression of TLR4 in nuclear factor kappa B (NF-KB) and MAPK pathways at different hours. Moreover, ANOVA analysis of covariance was used to compare this rate between these two pathways at different times. Statistical analysis was performed in SPSS software (version 17) and a p < /em>-value of

Based on the results, there was a significant relationship between TLR4 and HSP70 (p < /em><0.001). Furthermore, in the tissue with chronic periodontitis, there was a significant relationship between the affected tissue and TLR4 (p < /em><0.0001). It was also found that TLR4, MAPK, and NF-KB levels increased in the presence of HSP70.

According to the findings, it can be said that TLR4 expression levels increased in the presence of HSP70 in periodontitis and can increase even more by excitation of MAPK and NF-KB pathways.

Dental pulp stem cells (DPSCs) are known as multipotent stem cells which differentiate into three different cell lines, including osteocytes, chondrocytes, and adipocytes. Until now, dental precursor cells have been used in tissue engineering studies for pre-clinical applications. The dexamethasone in-situ forming implant (ISFI) is capable of releasing medicine that is trapped in the aquatic environment slowly and continuously in a few days to weeks. The present research aimed to investigate the ability of human DPSCs to differentiate into bone tissue in the presence of dexamethasone ISFI as a source of dental mesenchymal stem cells.

The DPSCs were extracted from the third molar tooth. To investigate the process of differentiation into osteoblasts, β-glycerophosphate, ascorbic acid, and dexamethasone ISFI in solution were added to the cells. The differentiation process was verified by Alizarin Red S stain, alkaline phosphatase activity (ALP), and western blot technique.

Based on the results of Alizarin Red S staining, extracellular matrix mineralization was increased in dexamethasone ISFI (i.e., implant) and standard (i.e., dexamethasone) groups. In addition, the ALP activity underwent an increase in these groups, compared to the related control group. Furthermore, the protein level of ALP,osteopontin, and runt-related transcription factor two increased in the group treated with dexamethasone ISFI, compared to the control group.

 Findings of this study indicated that dexamethasone ISFI could increase the process of differentiation of DPSCs into osteoblasts.

Third molar teeth are the most common teeth with agenesis. The absence of this tooth also increases the probability of anomalies in other teeth by several times. Since panoramic radiography is used to diagnose and plan treatment in orthodontic patients, along with routine clinical examination, this study aimed to determine the prevalence of third molar agenesis and incidence of other associated anomalies in comparison to that reported for the non-agenesis group using panoramic radiographs.

In this descriptive-analytical study, the pretreatment records of 562 patients were randomly collected. Out of these subjects, 538 patients were selected based on inclusion and exclusion criteria. The panoramic radiographic images of patients who did not have at least one third molar were assessed with regard to the presence of other dental anomalies, such as dental agenesis, hypodontia, hyperdontia, impacted canine, peg-shaped lateral incisors, ectopic eruption, microdontia, dilaceration, transposition, and transmigration. The prevalence of these anomalies was compared to that of a randomized control group selected from patients with the presence of each four third molars.

Out of 538 studied panoramic radiographs, overall, 13.7%, 13.5%, 13.4%, 5.9%, 2.7%, and 1.4% of them had at least one third molar agenesis, canine impaction, peg-shaped lateral incisors, missing teeth, transposition, and hyperdontia, respectively. The frequency rates of impaction and missing teeth were higher in the agenesis group (30% and 40.5%) than those reported for the control group (16% and 2.7%) (p < /em>>0.001), respectively. The presence or absence of other dental anomalies was not statistically significant between the two groups and two genders. In addition, the present study demonstrated that the probability of the presence of at least one type of other dental anomalies was higher in individuals with third molar agenesis in comparison to that reported for the control group (p < /em>>0.001).

Among different types of dental anomalies in the studied population, the probability of impaction and missing teeth was higher in the third molar agenesis group than that of the control group. Furthermore, the prevalence of third molar agenesis was not different between the two genders.

Today, smoking is recognized as a pervasive health problem, resulting in the growing number of people exposing to secondhand smoke. Regarding this, children, who are in the early years of their growth, are more vulnerable than adults. Exposure to environmental tobacco smoke (ETS) is considered one of the most toxic environmental exposures; in this regard, passive smoking is one of the most important public health problems. Considering the effects of cigarette smoke on C-reactive protein (CRP), which is an important risk factor for the development of cardiovascular problems, this study was conducted to compare the salivary CRP levels among passive smoker and non-smoker children and adolescents aged 12-15 years. The statistical population of this case-control study consisted of 80 children and adolescents aged 12-15 years (40 passive smokers and 40 non-smokers). To conduct the research, the unstimulated salivary samples were collected from the study population. Salivary cotinine level was measured using a cotinine kit and enzyme-linked immunosorbent assay technique. Moreover, a CRP kit and immunoturbidimetric method were used to evaluate the salivary CRP level. The collected data were analyzed in SPSS software (version 23) using an independent t-test. Based on the findings, the salivary cotinine levels were not significantly different among male and female passive smokers (0.12±0.34 and 0.15±0.37 ng/ml, respectively; p < /em>-value=0.8). Furthermore, no significant difference was observed among male and female non-smokers (0.014±0.01 ng/ml and 0.017±0.014 ng/ml, respectively; P-value=0.86). However, the salivary CRP levels were significantly higher in the passive smoker group (4.16±1.56 mg/l) than in non-smokers (3.175±1.009 mg/l; p < /em>-value=0.001). It can be concluded that children and adolescents' exposure to ETS would increase salivary CRP levels, which is a strong predictor of the risk of cardiovascular disease in adulthood, and consequently endanger the individual's health.

Effective cleaning of the canal is one of the most important biological goals of root canal treatment. Enterococcus faecalis is one of the most resistant bacteria following root canal treatment. The aim of this study was to compare the effect of EndoActivator and XP‐Endo Finisher File to the usual method in the cleaning of the infected canals with Enterococcus faecalis.

The present study was carried out on a total of 56 teeth. In order to induce infection, Enterococcus faecalis was cultured and incubated. The teeth were divided into four groups (with 14 teeth in each group). The XP‐Endo Finisher File, EndoActivator, 5.25% sodium hypochlorite, and normal saline were used in the first, second, third, and fourth groups, respectively. Finally, the number of grown colonies was counted and reported in the CFU/ml unit.

The mean number of colonies before using XP-Endo Finisher, EndoActivator, sodium hypochlorite, and normal saline were 169.7×104, 156.5×104, 193.2×104, and 215.9×104 CFU/ml, respectively, with no significant difference. After using XP-Endo Finisher, EndoAvactivator, sodium hypochlorite, and normal saline, the mean number of colonies were reported as 0.71×104, 4.78×104, 0.14×104, and 123.7×104 CFU/ml, respectively, indicating the clearance rates of 99.7%, 96.2%, 99.9%, and 42.9%, respectively. After the intervention, the studied groups were significantly different (p < /em><0.001) in terms of the contamination. The number of colonies in the XP-Endo Finisher group was significantly (p < /em>=0.04) lower than that of the EndoAvactivator group. These values were significantly (p < /em><0.001) lower in the three groups of EndoActivators, XP-Endo Finisher, and sodium hypochlorite than that of the normal saline group. There was no significant difference between the two groups of XP-Endo Finisher and sodium hypochlorite (p < /em>=0.608) and two groups of EndoActivator and sodium hypochlorite (p < /em>=0.507). The use of XP‐Endo Finisher, EndoActivator, and sodium hypochlorite resulted in significantly higher clearance than that reported for normal saline.

The highest rates of Enterococcus faecalis clearance were observed in the application of sodium hypochlorite, XP-Endo Finisher, and EndoActivator, respectively.