مجله تحقیق در علوم دندانپزشکی
سال بیستم شماره 2 (پیاپی 76، تابستان 1402)

To treat wounds, various treatment methods are used,including chemical, herbal, homeopathic and laser treatments, the main goal of which is faster, less complication, and at the same time lower cost of wounds. Topical phenytoin also has a positive effect on wound healing.The aim of present study was to investigate the antimicrobial effect of topical 1% phenytoin on microbial contamination caused by microorganisms affecting oral ulcer infection in an animal model.

In this experimental animal experimental study in 2019, 36 male rafts were selected. After anesthetizing the rats, the mandibular gingiva was flapped. Three types of microbial microorganisms including Candida albicans, Staphylococcus aureus and Actinomycosis were prepared. An equal number of microorganisms was placed at the incision site. Rats were randomly divided into two groups. In 18 rats 1% topical phenytoin powder was applied to the wounds, and in the remaining 18 rats no drug was applied to the wound. Finally, 36 samples of incisal biopsy were cultured in specific media for each microorganism and transferred to the laboratory. Colonies counted in phenytoin groups were compared with non-phenytoin groups. Data were analysed by Mann-Whitney test  by means of SPSS 22 software.

Mean±sd and Pvalue colonies of Staphylococcus aureus case and control groups respectively(124827±301378) and(807±1209),(P=0.259), Candida albicans(1750±1339)and(2357±4679),(P=0.423) and Actinomyces (16088±36721)and(47±114)(P=0.049)were not statistically significant between the phenytoin and control groups.

 It seems that 1% topical phenytoin powder after one use had no effect on reducing the microbial contamination of oral ulcers in laboratory rat.

Materials used for root filling include cold ceramics, gutta percha and endoseal MTA. In this study, our aim is to investigate and compare the marginal adaptation of channels filled with cold ceramic and gutta percha - endoseal MTA.

In this experimental laboratory study, 20 extracted human single-rooted teeth were used. After canal preparation, the teeth were divided into two equal groups including 10 teeth. In the first group, cold ceramics were prepared according to the manufacturer's instructions and compacted inside the channels. In the second group, they were filled with gutta-percha and endosyl sealer MTA by lateral compression method. After one week, cross-sectional incubation was performed on the samples at 3 mm and 6 mm end to obtain a thickness of 3 mm and the maximum gap in microns between the root and wall fillers in the cross section directly by electron microscopy. Material / dentin contact was measured by Pearson, Spearman, and t-test.

The mean distance between root and tooth filling materials in the cold ceramic group was4.96±2.87 microns and in the second group was 12.03 ± 5.22 microns, which was statistically significant (P = 0.001).

In root canal filling, the degree of edge alignment in teeth filled with cold ceramics is significantly lower than that of gutta percha and endothelial sealant MTA.

One of the main reasons for the failure of metal-ceramic restorations is insufficient bond strength between porcelain and metal, which depends on various factors, including the manufacturing method. The purpose of this study was to evaluate the effect of manufacturing method on bond strength of porcelain to titanium substructure made by EBM or Milling method.

In this in-vitro study two groups comprised of twenty metal bars each were prepared with EBM or Milling method. first a resin bar was molded into standard ISO:9693 dimensions of 25 mm × 3 mm × 0.5 mm. then it scanned and Ten bars from each group were manufactured using milling device from titanium disks or from an EBM device from Ti-6Al-4Va titanium alloy. bars were sandblasted with 110 μm aluminum oxide particles and were impregnated with bonding agent before the application of 1/1 mm of porcelain onto 8 mm × 3 mm rectangular area in the center of each bar porcelain. Afterwards, bond strengths of the samples were assessed using 3-point bending test with a Universal Testing Machine. Statistical analysis was performed using T-test and a significant level of 0.05 was considered

The mean bond strength of EBM group (34.36±3.67MPa) was lower than Milling group (46.52±4.34 MPa) and there was statistically significant difference between groups (p-value<0.001).

Bond strength of EBM-manufactured samples were lower than milled group while both groups exceed the minimum requirement of bond strength for metal-ceramic restoration according to ISO9693.

the malignant transformation of types of erosive and atrophic oral lichen planus has been further studied. Epithelial growth factor receptor is an intramembranous receptor which is related to carcinogenesis. The aim of the present study was to determine the expression of EGFR marker in erosive and reticular oral lichen planus and oral epithelial dysplasia.

In this cross-sectional descriptive-analytical study, after specimens selection(20 erosive oral lichen planus(with no dysplasia), 20 reticular, 20 oral epithelial dysplasia lesion, 10 Inflammatory Fibrous Hyperplasia (control group)) Immunohistochemical staining with EGFR antibody kit was performed and mean percentage of stained cells with EGFR Marker, pattern of staining, intensity of staining and stained-cell place  in each sample was investigated simultaneously   by two oral pathologist. finally, Data obtained were analyzed using SPSS software (VERSION 20) and Kruskal–Wallis, Mann–Whitney and Fisher tests (Pvalue<0.05).

There was no significant difference between the mean percentage of stained cells in erosive and reticular oral lichen planus(Pvalue=0.213).while erosive lichen planus and oral epithelial dysplasia presented significant difference in this regard(Pvalue=0.017). There was no significant difference between the frequency distribution of staining  pattern in groups(Pvalue=0.16)also there was no significant difference between the intensity of staining and the stained-cell place in 4 groups(Pvalue=0.19 , Pvalue=0.90).

The expression of EGFR in patients with oral erosive lichen planus and oral epithelial dysplasia was higher than patients with oral reticular lichen planus and control group and it probably shows the higher potential of dysplastic changes in erosive lichen planus than reticular.

Complicated dental treatments require great accuracy at work and of course accurate tools and imaging. The goal in this study was to determine the knowledge of dental post graduate students about the applications of cone beam computed tomography (CBCT) in dental treatments and related factors in Tehran dental schools in 2020.

This cross-sectional study, was conducted among 164 dental post graduate students in Tehran universities in 2020. They were provided with a questionnaire containing questions regarding demographic data ( age, gender, university, etc.) and 19 questions about the benefits, prescription and contraindications for CBCT in dental treatments. The data in the information form were assessed and for each dental student’s knowledge level was computed.

The average knowledge of dental residents was inadequate: 45/27 % (from 12/50% to 87/50%).There were significant relationship between  common term of CBCT and gender  and knowledge level  (p=0.00 and P=1.04) Therefore, more experienced and trained students had the highest knowledge levels regardless of gender or university.

: In conclusion, most of dental residents didn’t have a good level of knowledge about CBCT’s advantages .it is recommended that qualification programs be held for dental residents in order to strengthen their knowledge of CBCT.

Success in endodontic treatment is directly related to proper diagnosis and neutralization of microorganisms using mechanical and chemical methods and full canal obturation. Given that technical errors can affect the success of treatment and cone beame CT can detect these errors perfectly, the aim of this study was to determine the frequency of technical errors in root canal treatment using CBCT

In this descriptive-analytical study, 1067 endodontically treated roots in CBCT stereotypes were investigated. Fine-grained diagnostic radiographies were investigated in coronal, sagittal and axial planes. Filling length errors (tip to tip obturation, underfilling, overfilling, voide), errors during preparation (perforations, transport, broken instruments, missed canal and vertical root fracture) were recorded. The data were analyzed by Chi-square and Fisher's exact test

Moreover, the highest technical errors occurred were transport (23.8%), overfilling (21.2%), underfilling (21.1%) and voide (17.8%) and the lowest technical error occurred was zipping (0.3%). The highest technical errors occurred in the anterior regions including single canal teeth (18.7%) and single canal premolar (11.4%) and the lowest technical errors were found in the buccal and lingual canal of double canal canines (4 %). The frequency of radiographic lesions (p = 0.005) and the expansion of PDL (p <0.001) were significantly different between different dental areas; however, the frequency of resorption was not significantly different between different dental areas (p = 0.11).

The highest observed error was in the anterior area of a canal and the lowest error rate determined by the CBCT was related to the two canal canine (buccal) and two canal canine (lingual). transport, short-term filling, and void were the most endodontic errors and the lowest ones were related to zipping cousing with broken file and post perforation  in the root canal treatment.

Anterior crossbite is one of the most common orthodontic problems. Parents' level of awareness determines how they deal with their child's anterior crossbite problems. In the present study, the level of knowledge, attitude and practice of parents of primary school children about anterior crossbite was evaluated.

In this cross-sectional descriptive study, a questionnaire was designed to assess parents' knowledge, attitude and practice of children's anterior crossbite.  Face validity was confirmed through interviews, content validity was assessed by CVR calculation and construct validity was assessed using exploratory factor analysis. The questionnaire was provided to 250 parents and its construct validity and reliability were calculated using SPSS software. The final questionnaire was completed by another 250 parents to assess parents' knowledge, attitude and practice.

Based on factor analysis, the questionnaire was classified into 6 domains. The average scores in the areas of "treatment awareness", "complication awareness", "treatment attitude", "diagnosis attitude", "treatment practice" and "prevention performance" are equal to 19.48 ± 3.33 (out of 25), 10.19 ± 2.01 (out of 15), 7.53 ± 2.79 (out of 20), 9.83 ± 2.31 (out of 15), 19.4 ± 3.46 (out of 25), and 9.41 ± 2.07 (out of 15), respectively.

Parents had good knowledge, attitude and practice regarding anterior crossbite and only the "attitude towards diagnosis" of parents was relatively low which requires training in this field.

  Amongst the various calcified structures in the human body, teeth have gained lot of popularity in estimating the sex of an individual as they are highly resistant to destruction and decomposition. The aim of this study was to determine the diagnostic analysis of mesiobuccal and distolingual dimensions of canine teeth in determining the gender in dentistry students in 2020.

This cross-sectional analytical study was performed on all dental students of the 5th semester (130 students) in the School of Dentistry of Islamic Azad University in 2019 and with all teeth except the third molar. Eligible for admission, an alginate mold was prepared from the upper and lower jaw arches and poured by dental yellow acetone plaster. Then, mesiodistal and buccolingual dimensions of permanent canine teeth were recorded using digital caliper. Data were analyzed by t-test.

In general, the mean age of students was 23.97±1.43 years (22-26 years). Out of 130 students, 72 (55.4%) were male and 58 (44.6%) were female. The mean mesiodistal and buccolingual dimensions of maxillary and mandibular canine teeth on both right and left sides in students were not significantly different (p <0.05).

The analysis of  dimensions of the permanent canine teeth has not any important role on determination gender.

Successful treatment of pulp disease largely depends on good prosthetics restoration after endodontic treatment. Therefore, the aim of this study was evaluated of knowledge and practice of Yazd general dentists about restoring endodontically treated teeth.

In this descriptive cross-sectional study, the knowledge and practice of 150 general dentists in Yazd in relation to the restoration of endodontically treated teeth were studied by a valid and reliable questionnaire including demographic characteristics, 8 knowledge questions and 13 practice questions. Data were analyzed by SPSS17 software and t-test, ANOVA and Pearson correlation coefficient.

The dentists participating in the study were 54.7% female and 45.3% male with a mean. Their average score of knowledge was 11.08±2.89 out of 16 points. There was no statistically significant difference between the average score of knowledge in terms of gender, job experience and participation in related retraining (P-value <0.05). they preferred the cast posts and cores for the anterior (74 %) and posterior (74.7%) teeth. Most dentists used glass ionomer as a cement (92%) and normal saline as a root canal cleaner (72%).

the average score of dentists' knowledge regarding the restoration of endodontically treated teeth was good.

osteoblastoma is one of the rarest primary bone tumors with the potential for local invasion and recurrence. Although this disease is more common in vertebrae or small long bones, it rarely causes lesions in the jaw bones with a high tendency to involve the mandible. Correct diagnosis of osteoblastoma is very important because in cases where the lesion is percellular, it leads to misdiagnosis with osteosarcoma.

Case Report: 

The patient was a 52-year-old woman with a radiolucent lesion in the apical area of the molars. At right side of the mandible. The lesion continued from the mesial root of the third molar to the mesial root of the first molar. For histopathological examination of the tumor lesion after surgery, four lesions were removed. To remove them, the wisdom teeth and the first and second molars were also removed.

Jaw osteoblastoma is a rare tumor and its nonspecific clinical and radiographic manifestations cause diagnostic problems.