مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال بیست و هفتم شماره 3 (پیاپی 80، پاییز 1393)

Until now, different types of scaffolds are presented for hard tissue engineering and the research continues to find the best scaffold. The aim of this study was to prepare scaffolds using two types of composite materials, ChitosanTriCalcium Phosphate (C/TCP) and ChitosanTriCalcium Phosphate/ Hydroxy apatite (C/TCP/ HA) and to add either 10% or 20% gelatin to compare their influence on swelling ratio of the scaffolds and on their affinities towards Dental Pulp Stem Cells (DPSCs). Composite scaffolds containing 10 or 20 percent of gelatin were prepared by freeze drying method. To determine the percentage of water absorption, swelling ratio studies were performed. Cell attachment and cell viability of the composite scaffolds were studied using Scanning Electron Microscopy (SEM) and MTT (dimethyl-thiazol-diphenyltetrazolium bromide) assay. Data were analyzed using ANOVA and Turkey’s post hoc test. A P-value of <0.05 was considered to be statistically significant. The C/TCP scaffold and scaffolds containing 20% gelatin showed good swelling character. The macroporous composite scaffolds exhibited different pore structures. The biological response of DPS cells on C/TCP scaffold, C/TCP scaffold containing 20% gelatin, and C/TCP/HA scaffold was superior in terms of cell attachment, proliferation, and spreading compared to the other scaffolds (P<0.05). Considering the limitations of this in vitro studies, the results demonstrated that enhanced gelatin content in the C/TCP scaffolds do not improve initial cell adhesion and proliferation of the DPSCs on these scaffolds.

Considering the complications of root canal system, debridement would not be effective only by mechanical instrumentation. Therefore, root canal irrigants with the antimicrobial effect that can eliminate more microorganisms during treatment, becomes important. The aim of this study was to compare the antimicrobial effects of 2% thyme essence, 2.5% sodium hypochlorite (NaClO), and normal saline as root canal irrigants for primary molar teeth. This study was performed on 34 primary molars. Subjects were randomly divided into three groups (N=10). The root canals of the teeth were prepared up to the file #35 and all of the specimens were sterilized, and were then contaminated with entrococccus faecalis suspension (Enterococcus Faecalis ATTC 29212). After 48 hours of incubation, the specimens of each group were irrigated with corresponding irrigants. Then, the microbial specimens were collected with sterile paper points. After incubation, the numbers of Colony Forming Units (CFU) were counted using colony counter. Data were analyzed using Smirnov-Kolmogorov, Kruskal-Wallis and Mann-Whitney tests. Sodium hypochlorite showed the highest antimicrobial effect and showed significant differences compared with normal saline (P<0.001). However, the differences were not significant with thyme essence 2% (P=0.3). Thyme essence could be considered as a natural irrigator with a comparable antiseptic effect to sodium hypochlorite.

There is a risk of nerve injury during the extraction of the impacted third molars, in cases with proximity of the inferior alveolar nerve and this tooth. The aim of this study was to evaluate the effect of different various factors on the degree of vulnerability using CBCT (Cone Beam Computed Tomography) imaging technique. CBCT images of 191 patients referred for the exact assessment of the relationship between the mandibular canal and impacted mandibular third molars were selected. The position of these anatomical structures was evaluated at their contact point. The possible effect of gender, impaction form of the third molars, anatomical relationship between the third molars and the mandibular canal and the age differences were studied. Data were analyzed using Chi-square and Student’s t-test. There was a close relationship between the mandibular canal and impacted third molars in 81.7% of the patients. The contacts were shown to be significantly higher in females than males (P=0.01) and in the cases with the lingually position of the third molar and the mandibular canal (P<0.001). However, the age and impaction form of the teeth did not have a significant influence (P>0.05). The risk of nerve damage or exposure is increased in females and lingual position of the mandibular canal to the third molar in cases with higher proximity between these 2 structures in panoramic radiographs using CBCT images. Therefore, the surgeon must pay enough attention in these cases of third molar extraction.

Debonding of denture teeth from the denture base can be frustrating for both clinician as well as patient. The aim of this study was to determine the effect of different tooth preparations on the tensile bond strength of composite denture teeth to acrylic denture base material. In this experimental study, 108 anterior Glamour teeth were selected and divided into 9 groups, based on their preparation (physical: no physical change, glaze removal, creating two slots with 1.5 mm depth, creating a hole with 2.5mm depth, chemical: (without chemical materials, monomer, silane). Specimens were prepared and tested according to the methods of the International standards organization (ISO 20795-1). After attachment of teeth to acryl, the tensile bond stregth test was performed in a Universal Testing Machine (UTM) with a crosshead speed of 1mm/min and specimens were subjected to tensile force until failure. Data were analyzed with one-way ANOVA, Tukey HSD and Two-way ANOVA. There were significant differences between the bond strength of tested groups (P=0.012). Based on Tukey test, there was a significant difference between monomer/without physical change group and without/without (P<0.001) and control group. No significant differences were found between the bond strengths of the other groups (P=0.17). All specimens were debonded as cohesive failure. Application of monomer on the ridge lap surface led to improve the tensile bond strength between glamour composite denture teeth and Iranian acrylic resin, however physical changes were not effective. According to the cohesive failure of all the specimens, it can be concluded that the bond strength between this type of teeth and acrylic resin was stronger than the strength of teeth.

In the last decade, several studies have reported the isolation of stem cell population from different dental sources, while their mesenchymal nature is still controversial. The aim of this study was to introduce the isolating methods for stem cells from human dental pulp and to determine their mesenchymal nature before differentiation. One of the best sources for stem cell is dental pulp tissue. Dental Pulp Stem Cells (DPSCs) would be the most convenient source of stem cells because teeth were easy to retrieve and removed throughout life. Pulp is a specialized connective tissue including blood and lymph vessels, nerves, and the interstitial fluid. DPSCs can be found within the ‘‘cell rich zone’’ of pulp. DPSCs have been isolated for the first time in 2000 by Gronthos; these cells exhibited a differentiation potential for odontoblastic, adipogenic and neural cytotypes. Gronthos isolated stem cells in 2 different The enzymatic digestion method and the second was out growth, these cells could be cryopreserved in liquid nitrogen. It has also been shown that human DPSCs can be used for complex structures such as pulp or woven bone formation in vivo. DPSCs originate from the cranial neural crest and have neural characteristics such as the expression of neurotrophins. Therefore, DPSCs may represent a promising source in cell therapy for neurological disorders. Characterization of these cells and determination of their potentialities in terms of specificity of regenerative response will form the foundation for development of new clinical treatment modalities, whether involving directed recruitment of the cells and seeding of stem cells at sites of injury for regeneration or use of the stem cells with appropriate scaffolds for tissue engineering solutions. Such approaches will provide an innovative and novel biologically based on new generation of clinical treatments for dental disease.

Successful pediatric dentistry depends on the dentist's technical skills, as well as his/her ability to acquire and maintain a child's cooperation. The correction of dentist’ performance in this area affects the view of parents and increases the quality of dental services. The aim of this study was to evaluate the attitudes of general dentists toward behavior guidance techniques in Isfahan. In this descriptive- analytic cross-sectional study, 100 general dentists of Isfahan city were selected with simple random sampling technique. They were asked to complete the questionnaire inquiring their attitude toward four different behavioral management techniques. An appropriate question about each of the methods was proposed by the authors, along with demographic characteristics including: gender, age, university, year of graduation, work experience, the mean number of pediatric patients referred in one month was provided in the form of a questionnaire. To evaluate the attitude of dentists to the questionnaire, the score from 1 to 5 was given to each item and the total score was considered. Higher score indicated more positive attitude of dentist. Data were analyzed using T-test, Pearsons correlation and one-way ANOVA (P<0.05). The mean scores for dental behavioral management techniques were positive reinforcement (4.2±2.7), general anesthesia (3.5±4.4), N2O sedation (3.4±4.4) and pharmacologic sedation (3.2±2.7), respectively. There were no significant differences between the mean score of dentist attitude and age, gender, clinical experience and the number of pediatric patient (P>0.05). General dentists’ attitudes towards different behavior management techniques were associated with age, gender, clinical experience and the number of pediatric patient. General dentists’ tend was more towards non-drug behavior control methods such as positive reinforcement.

AIDS-associated oral lesions are important, in terms of diagnostic-prognostic role and monitoring patients; moreover some of them may reduce patient’s quality of life. The aim of this study was to determine the prevalence of oral lesions in HIV patients. This descriptive cross-sectional study was carried out among a total of 62 HIV+ patients who attended a counseling and treatment center in Rasht. Demographic information, drugs and laboratory status were extracted from patients’ files. Data were analyzed using univariate and multivariate logistic regressions with multiple linear regressions. From 62 cases, 50 were male and 12 female and the mean age was 40.5±11.3 years. 59 patients had oral lesions including periodontal disease (95%). The most prevalent oral lesions included: periodontitis (67.7%), oral candidiasis (41.9%) of erythematous (35.4%) and pseudomembranous types (6.45%) and angular cheilitis (12.9%). Patients with removable denture presented a higher rate of erythematous candidiasis and angular cheilitis (P=0.001). In this study, periodontal diseases were rosed by the post-diagnosis years (P=0.024) and the antiretroviral medications (P=0.002). Patients on the prophylactic medications (P=0.043) were less likely to have erythematous candidiasis; age may caused angular cheilitis (P=0.041). Pseudomembranous candidiasis was inversely correlated with CD4 + L levels (P=0.052). The majority of the cases in this study were IV drug user males within the 4th decade of life. Although oral lesions were not common, but the dental and periodontal statuses exhibited poor oral hygiene which need more attention.

Tobacco kills 5 million people worldwide annually, according to the Health Ministry reaches this number is about 70,000 people a year in Iran. Dental professionals are in a unique position to promote smoking cessation due to the opportunity for regular interaction with their patients. The aim of this study was to investigate knowledge, attitudes, and skills of dental students at Tehran and Shahid Beheshti dental schools towards tobacco cessation counseling in dental office. In this cross-sectional study, the target group was dental students at Tehran and Shahid Beheshti dental schools, and the sampling method was census. A questionnaire on the knowledge, attitudes, and skills towards tobacco cessation counseling in dental practice was administered to the students (n=93). Data were analyzed using T-test. The response rate was 100% (93 students participate in this program and all of them filled the questionnaire). The average score of knowledge at Tehran and Shahid Beheshti dental schools was 17.5 and 18.4, respectively (P=0.09), the average score of attitudes was 33.5 and 33.1, respectively (P=0.80). There were no significant differences between the two dental schools in these parts. The average score of skill was 11.9 and 16.6, respectively. The differences between the students of two dental schools in skill were significant (P=0.002). Although the attitude of dental students at Tehran and Shahid Beheshti schools towards tobacco cessation counseling seemed to be fair, some deficiencies existed in their knowledge and skill. Dental education programs should be implemented properly in this field.

According to the concerns that people are not familiar with the word surgeon - a dentist that all general dentists use this word (surgeon - a dentist) in their office boards and given to the people expectations of this word, teaching these surgeries in the dental curriculum is limited. There is a lack of information about the public awareness of this term. As a result, the aim of this study was to determine the people awareness about the meaning of the word ‘surgeon’ on the dental offices board and its related factors in Tehran, in 2010-11. This study was conducted on 385 individuals by the descriptive - cross sectioned method in Tehran. Their awareness was defined and the role of relevant factors like individual characteristics, age, gender, socioeconomic (education, job, visit the dentist) were studied. Data were analyzed using K2-test. 57.4% were female and 42.6% were male. Their average age was 50 years. The minimum and maximum age was 20 and 77, respectively. 43.6% of them had academic education and 56.4% had a diploma or less. 4.9% of them had well knowledge, 30.1% had average and 65% had poor awareness. In other words, 35% had acceptable awareness and 65% had unacceptable. It seems that people unawareness of the word surgeon - a dentist is a serious concern. Because this lack of knowledge has led to referring the people to non-expert dentist for the surgery, that may causes serious problems.

The aim of this review article was to present the information have been published, regarding the functional properties of Zirconia until today. A review of the literature was carried out in MEDLINE database using key words (Dental ceramic, Zirconia, 3Y-TZP, Clinical performance, Machining and Transformation toughening). These searches were limited to the articles published after the year 2000. Despite excellent clinical results in short-term studies, there is still a major need to have more clinical and laboratory long-term information about zirconia restorations.