مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال سی و سوم شماره 4 (پیاپی 105، زمستان 1399)

Poly methyl methacrylate (PMMA) is still the most commonly used material in prosthetic dentistry. However, there are problems with the mechanical properties of this type of material including low flexural strength. Addition of nanoparticles into the polymer is one way to improve the mechanical properties of acrylic resin. In the present study, the effect of silicon dioxide (SiO2) nanoparticles addition into the heat-cured acrylic resin in different concentrations was investigated. Because of the controversy had been observed in previous articles, the aim of this study was to investigate the mechanical properties of PMMA/SiO2 nanoparticle obtained from different percentages of SiO2.

In this in-vitro study, acrylic resin specimens containing 0, 1, 3 and 5% silicon dioxide (SiO2) were prepared. The specimens were placed inside the gypsum molds and placed under pressure for three times. The mold cured in boiling water for 30 min. A trimmer was used to remove the additives. Sandpapers with 180, 320 and 600 grains of silicon-carbide were used for final finishing and polishing. Finally, the flexural strengths were measured using a universal testing machine. Data were finally analyzed by ANOVA and Tukey tests at a significant level of 5% using SPSS software.

The mean flexural strengths and standard deviations of control group, 1% filler, 3% filler, and 5% filler, were 57.24±8.30, 69.98±7.26, 60.16±9.18, and 61.59±9.28 MPa, respectively. After comparing significant values between each group with the control group, a significant difference was observed between the control and 1% filler group (P=0.021). However, no significant difference was observed between 3 and 5% fillers with the control group or each other. The significant differences (P-value) between 3% filler and control group were 0.892 and between 5% filler and control group was 0.975.

The results of the present study showed that the use of low percentage of silicone dioxide (SiO2) nanofiller could improve the flexural strength of poly methyl methacrylate acrylic resin.

Pulpal exposures originated from the external cervical root resorptions have major effects on the treatment and prognosis. Therefore, the aim of this study was performed to compare the two different imaging systems-digital radiography with PSP (Photostimulable Phosphor) sensor in three horizontal different views and CBCT (cone beam computed tomography) images to assess the pulpal exposure in simulated cavity of external cervical root resorptions that was performed in 1398 in the School of Dentistry of Azad University.

40 intact maxilla anterior teeth with straight roots were included. Teeth were randomly divided to two groups (20 teeth with and 20 without pulpal exposures). Each sample was assessed using PSP digital radiography (in 3 horizontal angles) and CBCT image system, to detect the presence of pulpal exposures. False negative and false positive results in 2 imaging procedures were judged with ratio test.

The results showed in CBCT (P.P.V=85.7%) and (N.P.V=89.5%), and in digital intraoral radiography (P.P.V=80%) and (N.P.V=80%) in proximal defects. Ratio test showed that there were no significant differences in the proximal defects (P<0.4).

The results showed that there were no significant differences in detection of exposure in the proximal surfaces between two imaging systems.

Periodontitis is an inflammatory multifactorial disease in oral tissues and many genetic reasons and environmental factors responsible. Vitamin D deficiency has been determined to be related to periodontal disease. This aim of this study was to investigate the association between rs7975232 polymorphism in vitamin D Receptor gene and periodontitis in 100 patients (as patient and control groups).

Blood samples from 50 patients and 50 control groups were selected and DNA from the samples was extracted by the DNA extraction kit. Genotyping was used by Tetra Arms-PCR method. The use of sequencing was confirmed by the Tetra Arms-PCR genotyping results. Then, statistical analysis was performed using SPSS statistics 20 software and T-test.

Frequency of AA, AC, and CC Genotypes were 25 (50%), 14 (28%), and 11 (22%) in patients’ cases, and 26 (52%), 16 (32%) and 8 (16%) in controls, respectively. AA genotype was the highest genotype between the patient and control groups. Statistical analysis showed no significant association between this type of polymorphism and periodontitis disease in the studied samples (P=0.67).

This finding showed there was not significant association between rs7975232 polymorphism in vitamin D Receptor gene and periodontitis disease in the studied samples. To confirm the results of this study, further studies with large sample size and different types of population are recommended.

Child’s oral health is believed to be related with maternal dental fear and anxiety. The purpose of the present study was to evaluate the relationship between the demographic status and maternal dental fear and anxiety and its effect on child’s dental caries.

This descriptive and analytical study conducted among 374 mothers which had attended to pediatric department of Tehran University of Medical Sciences for their child’s dental treatments in 2019 were evaluated in the present study. In addition to dental fear survey (DFS) and modified dental anxiety survey (MDAS) questionnaires, demographic information, age, marital status, family income, and educational level of the mother was recorded. Dental visit frequency and previous negative experience were also recorded. DMFT/dmft (decayed, missed, filled teeth) of the children was recorded according to WHO criteria. To assess the relationship between the variables, Pearson correlation and multiple linear regression were used using SPSS25 software.

The mean age of the mothers was 35.66±15.75. There was no relationship between maternal dental fear and anxiety and children’s dental caries status (P=0.738). There was no relationship between the mothers’ age and dental fear, and anxiety (P=0.943). Previous negative experience and education were related to the dental fear and anxiety (P=0.02).

dmft of the children was not correlated with the maternal dental fear and anxiety. Higher education which was related with less dental fear and anxiety. Previous negative experience is one of the major factors influencing the maternal dental fear and anxiety.

Providing quality services is one of the important goals of the health system. Dental services and treatments are expensive. The aim of this study was to investigate the factors influencing the perceived quality of dental treatment services.

This descriptive-cross study conducted in 2 qualitative-quantitative phases. Data were collected using interviews and pairwise comparison matrix with 20 dentists working in NAJA dental clinics who were selected by targeted sampling. The validity and reliability of the interviews were determined by long-term engagement of their peers and negative case analysis. The validity of the pairwise comparison matrix was determined through the incompatibility rate (>0.1). Data were analyzed by coding and effect intensity tests (R+J), descriptive statistic test (mean, standard deviation) using SPSS23, Maxqda and matlab R2017b.

Content analysis of the interview showed that tangible factors, assurance, trust, and empathy are the factors affecting the quality of dental treatment services. In the second phase, data analysis showed that trust and empathy (28.204), assurance (24.356), and tangible factors (17.798) are the most to the least important factors in the quality of dental treatment services (P=0.1).

Trust and empathy were the most important factors in the quality of dental treatment services. Managers of dental clinics and dentist need to improve the quality of dental treatment services by emphasizing respect for patients in accordance with the promise to act in the field of providing treatments to patients.

Human ergonomics or engineering with proper design and change of work and requirements creates the most productivity based on human physiology. The purpose of this study was to determine the level of awareness of dental students of Isfahan University of Medical Sciences about the basic principles of ergonomics in dentistry.

In this descriptive-analytical, sectional study, a questionnaire containing 10 questions was distributed and completed by easy sampling method among 74 final year students of the general doctorate of Isfahan school of dentistry. After collecting the questionnaires, the students were given an educational pamphlet. To evaluate the questionnaires, each correct answer was given a score of one and the wrong answers were given a score of zero. Data were analyzed by T-test, Kai Square, and Mann-Whitney statistical tests using SPSS23 software. P<0.05 was considered as a significant level. P<0.05 was considered as a significant level.

The average score of the knowledge of principles of ergonomics was intermediate (6.23±1.25). Student knowledge was not significantly different based on the student gender (P=0.25) and academic semester (P=0.059). Also, 55% of students had a history of muscle pain that did not have a significant relationship with gender (P=0.258) and average score of the knowledge (P=0.288).

Unfortunately, ergonomics cannot be considered part of the principles of dental education and even later. Musculoskeletal pain is one of the most common complaints of dentists and is a factor in reducing their quality and function. Therefore, it seems that training and evaluation of ergonomic principles in dental education is necessary.

Pregnancy is a period with hormonal and psychological changes affecting women’s oral health. The aim of present review study was to evaluate, elaborate and categorize factors affecting oral health status of pregnant women.

A literature search with the following keywords: pregnancy, “pregnant women”, “pregnant mothers” and “expectant mothers” , AND dentistry, “dental health” and “oral health” in PubMed and Scopus was performed from 2009 to 2019. Search results included 1435 articles which 467 duplicate studies were excluded. Finally, 30 articles were included in the study. Oral health outcomes were categorized and significant relationships with determinants and risk factors were reported.

Most studies (70%) were performed cross-sectionally. Among the studied outcomes, dental visit, periodontal disease and dental caries were the most common. The most studied independent variables were socioeconomic factors and demographic factors, followed by behavioral and enabling factors. The lowest frequency was related to the systemic factors. Mothers’ education and age were examined more than other variables and in about 40% of studies had significant association with outcomes. Dental counseling was assessed in only 3 studies and in all three studies, the relationship with outcome was significant.

Socioeconomic, demographic and enabling factors could affect the oral health of pregnant women.

Information collection about the malocclusion and oral health in blind children is essential to plan for their education in schools. Therefore, this study aimed to evaluate the status of malocclusion and oral health among blind children and teenagers in Mazandaran, Iran.

The population of this included 150 blind children and teenagers aged from 10 to 18 years who were referred to the public and private centers cities including Sari, Babol, Freydoonkenar, and Babolsar in Mazandaran, Iran in 2019. Information on maxillary occlusion status, oral hygiene index, and DMFT index was extracted through clinical examination. Data were analyzed using SPSS23 software by ANOVA and Chi-square tests in addition to the descriptive statistics.

The mean DMFT was 10.25 (SD 4.67). Oral hygiene status was good in 16% of participants, moderate in 82%, and poor in 2%. There was no significant difference between girls and boys in terms of oral hygiene status (P=0.5). In all cases, 35.8% had class I malocclusion, 29.8% had class II malocclusion, and 14.6% had class III malocclusion. Class II malocclusion was more common in girls and class I in boys (P=0.01).

Dental caries and occlusal abnormalities were common among blind children and adolescents living in Mazandaran province. Addressing the oral and dental needs of the blind should be a priority for health policymakers in this province in Iran.