مجله تحقیق در علوم دندانپزشکی
سال شانزدهم شماره 3 (پیاپی 61، پاییز 1398)

Oral microbiota could proliferate the microspace between the implant and abutment, thereby cause inflammation in the peri-implant tissues and adjacent bone. This study aimed to investigate the effect of two types of abutments (zirconia and titanium) on microleakage at implant-abutment interface area under oblique cyclic loading in vitro.

In this in vitro study, 12 implant-abutment assemblies were used, each containing six sets with either zirconia or titanium abutments and vertically mounted in the modified resin blocks of auto-polymerized polyester base. The specimens were then subjected to oblique cyclic loading of 75 N at a 30 ± 2 degrees angle to the longitudinal axis of the implant with a frequency of 1 Hz in 500,000 cycles, equivalent to 20 months of human mastication. To determine the penetration of fuchsine into the implant-abutment interface, the implants were cut by cutting machine from the middle. Then, the rate of penetration of fuchsine in each sample was measured by a stereomicroscope with a magnification of 75 × at three points of each semicircle, and the average of these six points was recorded as a microleakage. For comparison of the microleakage after loading, t test was used. All tests were performed in SPSS ver.22 software and a significant level of 0.05 was considered.

The amount of microleakage after oblique cyclic loadingwas statistically significantly higher in the zirconia abutments (66.08±11.66) compared to the titanium abutments (39.17±10.65)following force application (P = 0.002).

The microleakage following oblique cyclic loading is different depending on the type of abutment, so that the titanium abutments showed significantly less microleakage than the zirconia abutments.

Using Stainless Steel Crowns (SSC) for Early Childhood Caries usually causes an unpleasant condition in the aesthetic of the patients. The aim of this study was to evaluate the effect of different surface treatments and bonding systems on shear bond strength of composite veneer to Stainless Steel Crown.

In this in vitro study, 120 SSC were divided into 6 groups according to the surface treatment method (without surface treatment, diamond bur or sandblast) and bonding agent (alloy primer+Clearfil SE Bond or G Premio Bond). Shear Bond Strength (SBS) of composite cylinder to SSC was measured. Data were analyzed using ANOVA and Tukey. P-value <0.05 was considered statistically significant.

SBS with Alloy Primer+Clearfil SE Bond (37.53±9.13) was significantly higher than G Premio Bond ( 30.54± 12.34) (P-value <0.0001). Sandblast showed significantly higher SBS in comparison with two other groups (P-value <0.0001)

Based on the results of this study, sandblasting has the highest SBS in comparison with the other methods of surface treatment. In the absence of sandblast, the application of the Alloy Primer+ Claerfil SE Bond on the SSC surface will provide better bond to resin composite.

Regarding the prevalence of postoperative pain of impacted wisdom tooth and the fact that Pregabalin herbal medicine has been reported to reduce the pain, and to determine the effect of its consumption/ non-consumption on the amount of pain after surgery of Impacted Wisdom Tooth, this study was conducted at 2018 in Department of Oral 7 Maxillofacial surgery, Dentistry faculty, Tehran medical sciences, Islamic Azad University.

This study was performed as a split Mouth-type clinical trial. A total of 30 patients who referred for pulling out the two-way impacted wisdom tooth and, after justifying the plan, they announced their written and informed consent to collaborate with the plan. One side of the jaw is randomly assigned to the control group and the other to the experimental group. The dentist surgeon and consuming material were the same. In the experimental group, half an hour before surgery, one pregabalin 300 mg was prescribed with 50 ml of water but the control group did not receive the drug. The surgical distance in 2 sides was 2 weeks and the pain was measured at intervals 2, 4, 6 and 8 hours after surgery based on 10 VAS and assessed by Mann-U-Whitney and Kruskal Wallis tests.

The study was performed on 30 or 60 samples, 70% of the samples were male and 30% were female at the age of 31±8.2.The pain level was similar in 2 groups at the second hour (P<0.6) but at the 4th hour  it was 5.63±1.94 and 3.7±1.56  in  control and experimental gourps, respectively.At 6th hour, it was 6.93±1.95 and 4.55±2.2 in control and  experimental groups and at 8th hour, 8.35±1.76 VS 5.9±1.94, respectively. (P<0.01) and (P<0.002).

It seems, Pregabalin reduces the pain in Impacted Wisdom Tooth surgery and pain reduction raised from 4th to 8th hour.

Abstract
Malocclusion has an important effect on patients’ social behaviors and mental situation and might affect their oral health-related quality of life (OHRQoL). The aim of this study was to assess OHRQoL in patients attending orthodontics department of Isfahan Azad University.
The present descriptive study was conducted on 77 patients in need of orthodontic treatment applying a census sampling method. Before entering the treatment phase, volunteer patients filled out Oral Health Impact profile-14 (OHIP-14) questionnaire. Index of Orthodontics Treatment Need (IOTN): Aesthetic Component (AC) and Dental Health Component (DHC) were used to assess patient’s orthodontic treatment need. Student’s t-test, Mann U Whitney test, analysis of variance, kruskal wallis test, Pearson and spearman correlation coefficient, and linear regression model served for statistical analysis.
The mean score of OHIP was 14.1 (±8.9, range 0-35). Orthodontic treatment need was high or very high among 65% of the participants based on DHC.  Based on AC, 33.8% of patients reported definite need to orthodontic treatment. A significant association existed between OHIP and DHC (r=0.28, P=0.017), and between OHIP and AC (r=0.24, P=0.036); however, it was weak. Based on linear regression model, OHIP was significantly associated with education (P=0.026) and AC of IOTN (P=0.026).
Although, the relationship between malocclusion and OHRQoLin the present study was week, it is recommended for orthodontist to consider the effects of oral problems on patients’ quality of life, in addition to their professional methods in diagnosis and treatment planning.

There are so many studies about effect of colored drinks and mouthwashes on discoloration of different dental ceramics. However, little is known regarding the effect of colored drinks on discoloration of monolithic zirconia .The purpose of this invitro study  was to evaluate the effect of different surface treament methods on color stability of monolithic zirconia.

: this experimental study was conducted in vitro on monolithic zirconia ceramics. Twelve pre-tinted specimens of monolithic  blocks (1.5 mm, 14 ,14 mm) were prepared and divided into 2 groups (A) glazed  and (B) polished after glaze  .Specimens were sintered and glazed  and Specimens of group B were prepared and polished. The specimens were placed in Golestan bag teas (ph = 5) for two weeks and color of the specimens were measured using spectrophotometer before and after immersion. the color changes (ΔE) were determined by Mann-Whitney test.

This study showed color change rate in the polish group was 3.2 ± 0.1 and in the glaze group was 1.07 ± 1.1, p˂0.7, and the color change in the polish method was about 2 times more that of glaze method which is significant (p<0/004).

Glaze Group seems to have less color change compared to polish group.
 Color stability, Monolithic Zirconia,  Dental ceramics

One of the well-known bacteria in dental unit water contamination is Pseudomonas aueroginosa. The aim of the present study was to evaluate the amount of Pseudomonas aeruginosa species infection in the dental unit water samples of Dental Faculty of Mashhad University of Medical Sciences.

Water samples collected randomly from the turbines of 10% of the active dental units in Mashhad Dental Faculty. Samples were collected at three time points including beginning of the day prior flushing, beginning of day after 2 min flushing, and middle of day after 20 sec flushing. Data analyzed with SPSS version 20 software using two-way ANOVA test and 95% of confidence interval.

All samples were infected at the first time point. At the beginning of the day prior flushing, the water contamination was higher than ADA standard in all departments except periodontology and operative dentistry. Water contamination decreased significantly after flushing at the beginning of day and middle of day measurements (P-value < 0.001). However, no significant difference was observed between beginning of day after flushing and middle of day samples.

High bacterial infection was found in dental unit water samples of Mashhad Dental Faculty regarding P. aeruginosa bacteria. Flushing was an effective measure to reduce the bacterial count of dental units.

Assessment of vertical dimension of occlusion is an important step in the prosthodontic treatment of edentulous patients. The Objective of this study was to determine the correlation of the lower third of the face in occlusion and facial and palm indexes in dental students of Islamic Azad University of Tehran at 2017-2018.

In this correlation cross-sectional trial, 100 subjects (50 men &50 women( were studied. The inclusion criteria were the subject’s desire to participate in the study, facial symmetry, no history of trauma in the face and palm, and no history of facial plastic surgery.Facial indices and the palm size was recorded with a bolly gauge caliper with a precision of 0.1 mm. the correlation between the height of the lower third of the face and each of the facial and palm indices was determined by Pearson correlation coefficient. Correlation coefficient (R) and consistency (R2) were calculated.

The mean age of male was 23.02 years and the mean age of women was 24.6 years. All indices had a moderate correlation (0.4<r

It seems that anthropometric and palm indices can be used as auxiliary indices, and can not use lonely.

 Having positive attitude, awareness and interest in students toward their field of study can create a sense of adjustment between their career future and their needs and expectations. This study aimed to establish and compare the degree of awareness, attitude and interest amongst dentistry and pharmacy students of Tehran Medical universities toward their field of study in university.

 This descriptive- correlation study was conducted on 314 basic sciences and graduated students of dentistry and pharmacy of Tehran Medical, Shahid Beheshti and Azad universities of Tehran with the use of quota sampling. Data collection instruments were self-made questionnaire, demographic information, student's awareness, attitude and interest.

 in this study, there was direct relationship between awareness and interest in the field of dentistry in Islamic Azad and Shahid Beheshti universities with the correlation of 0.14, 0.02, and 0.25 respectively and in the field of pharmacy, it was also a direct relationship with the correlation of 0.18, 0.07,and 0.4 respectively. Degree of awareness in graduated students of Islamic Azad universities and Shahid Beheshti was significantly more than basic science and degree of attitude in all three universities was significantly more than that of the graduation time (p>0.05). Degree of interest in both grades, according to the university, didn't have a significant difference.

  based on the direct and significant relationship between awareness and interest on learning, paying attention to this issue should be a priority for medical training centers planning.

 According to the commonness of academic Failure and its well-known side- effects .the question that arises is how the primary education course should be to prevent the academic failure. Therefore this study performed on the different position managers of  Tehran Azad dental university to answer to this guest ion in year 2018
Materials and 

This descriptive study surveyed the view of several faculty members of Tehran Azad dental university. This questionnaire includes 7 indices which each of them Has at least 10 indices as a subsidiary like need assessment of education and  investigation  of  Learners  features. They have asked to sign from zero to five for each of the indices. The  rate of each seven indices was designated. Also the most import index was found and presented and analyzed with  Wallis test for statistic evaluations.

 The questionnaire of this study performed to opinion poll of 121 faculty members who have the qualification and 66/8/ were men and 33/2/ were woman 75% were graduated of  bachelor  and upper degrees  and 37.7%  had  job experience more than 20 years. The most important index among 7 indices was the effective performance of educational  course with the rate of 4/11 and after that  was the knowledge and basic learnings , with the rate of 3/89 and the minimum rate was the preventive indices of academic failure with the rate of 3/06. (p<0001)

  According to this study it seems that the primary learning  course for the new students of Tehran Azad dental university is every effective  in order to parent academic failure.

Drug abuse can have harmful effects on the health of the body, especially oral health. The aim of this study was to investigate the oral manifestations of addicts in four maintenance centers in Tehran in 2017.

In this descriptive study, patients' demographic data were recorded in a questionniare, then oral and teeth were  clinically evaluated. Data were analyzed by chi square, Kruskal-Wallis, Mann U-Whitney and Spearman tests with a significance level of 0.05.

The study was performed on 392 addicted individuals. Among this population, 192 person (49%) were women and 200 person (51%) were men. The mean age was 34.9±9.4 years.  Methamphetamine & morphine were the most commonly used drug among women and men, respectively. At least one oral lesion was  present in 31% of women and 18% of men. The erythematous and spongy gingiva with round margin was the most frequent oral manifestation. There was a significant relationship between the duration of addiction withdrawal and all of the variables of color, consistancy, marginal contour and gingival tissue in men (p = 0.03). There was a positive correlation between DMFT index and duration of addiction in women  (p <0.001) and  men (P<0.05). About 75% of the subjects had dry mouth and dental attrition , which increased with the duration of addiction.

Methamphetamine & morphine were the most commonly used drug among women and men, respectively. Dry mouth, spongy and erythematosus gingiva were the most common oral lesions in the addicts.