Journal of Dental Medicine

Background and Aims: The objective of the present study was to investigate knowledge and attitude of senior dental students towards HIV/AIDS. Its result could help in promotion of education.

Materials and Methods: This educational research was carried out in two state dental schools in Tehran. The senior dental students in Tehran and Shaheed Beheshti dental schools were asked to fill in a self-administered questionnaire regarding their age, gender, parents' job, knowledge and attitudes towards treatment of patients with HIV/AIDS in Autumn semester 2007. Fifty five dental students (83%) including 27% male and 73% female in Shaheed Beheshti and fifty five dental students (85%) including 34% male and 66% female in Tehran dental schools were participated. The score for knowledge and attitude of the students were calculated separately. The data were analyzed using Independent sample t-test.

Results: The mean percentage of knowledge and attitude scores were 76.5% (at rang 1-3) and 50% (at range 1-5), respectively. Nearly all of the students believed that all patients should be considered as HIV positive in dental practice, while 49% preferred to refer HIV positive patients. Knowledge and attitude of students were not significantly associated with the gender and knowing HIV positive person (P>0.05).

Conclusion: There is a need to improve knowledge and attitudes of dental students towards HIV/AIDS. It is suggested to emphasize on this subject in dental schools curriculum in Iran.

Microstomia is defined as an abnormally small oral orifice. Microstomia can occur as a result of trauma from electrical and thermal lesions, chemical burns and trauma from surgeries. Prosthetic rehabilitation of microstomia patients presents difficulties at all stages, from the preliminary impressions to fabrication of prosthesis. For impression procedures different treatment methods have been suggested. Swing hinge and collapsible dentures are used to provide prosthodontic treatment to patients with microstomia. Not only is such a prosthesis difficult to fabricate, but may be expensive. The literature contains reports on the fabrication of sectional denture with the denture pieces connected by different designs. This article describes a simple method of fabricating a 2-pieces denture using removeable partial denture metal framework to connect the sections, for a patient with limited oral opening. Combination of metal framework and sectional complete denture for a patient with limited oral opening is an acceptable, effective and available method.

Surgical and prosthodontic implant complications are often the case of inadvertent improper diagnosis, planning, and placement. These complications always pose a significant challenge in implant dentistry. In this article, it is attempted to depict a new technique in which advanced software program along with newly developed CAD/CAM technology called rapid prototyping will be used. This technology permits graphic and complex 3D implant simulation and then fabrication of computer-generated surgical templates. The best position of implants planned at first by taking into consideration of encased bone density of each implants and then existing occlusion. In this paper, the evolution of Computer Guided Implantology and the many benefits achieved from this very sophisticated technology described as a literature review.

Background and Aims: Studies show that sucrose containing chewing gums are cariogenic. The aim of this study was to evaluate the effect of two commercial chewing gums with and without sucrose on dental plaque accumulation compared with the control group.

Materials and Methods: In this clinical study, plaque accumulation during three 7-day periods (with two weeks interval) was recorded (Sillness & Loe Index) in a group of 23 volunteer male dental students who chewed in the first two periods sugar-free or sugar-containing chewing gums (Olips and Orbit, respectively) and in the last period did not chew any gum. Participants were asked to chew daily five gum sticks after meals for about twenty minutes. The data were statistically analyzed using Repeated Measure ANOVA and paired-T test.

Results: The results showed that chewing any gum even sucrose-containing gum decreased the level of dental plaque accumulation (P<0.001). However, the decreasing effect of sugar-free gums was significantly higher (P<0.001).

Conclusion: Although sugar free gum was more effective than sugar containing gum on reducing dental plaque accumulation, chewing even sugar containing gums could decrease the level of dental plaque.

Background and Aims: Association between patient satisfaction and success of the treatment determines the quality of health care. Measuring the level of satisfaction is an important factor for improving the quality of services provided by a system, so it is necessary to determine the expectations of patients. The aim of this study was to evaluate the patient satisfaction from services provided by the dental faculty of Tehran University of Medical Sciences.
Materials and Methods: In this descriptive and cross-sectional study, 385 patients were randomly selected from different departments of dental faculty including prosthodontics, endodontics, periodontics, operative dentistry, radiology and oral medicine. A two-part questionnaire including demographic characteristics of patients and satisfaction from reception process, infection control, student and personnel behavior, and the outcome of treatment was filled out by patients. Data were analyzed using SPSS software.
Results: The most dissatisfying factor was the time wasted in paying the cost and the most satisfying factor was student behavior. General satisfaction form the process was evaluated (complete satisfaction 51.9%, partial satisfaction 38.4% and dissatisfaction 9.6%), and 62.9% of patients were completely agree with introducing dental faculty to others.
Conclusion: The most satisfying item was student behavior which indicates that this factor is of great importance in increasing the quality of treatment. The deficiencies determined by patient can provide reliable data for determination and regulation of health care policies.

Background and Aims: Conventional radiological equipments in our country are going to be converted to digital system using computed radiology (CR) technology. If we know the accuracy of digital panoramic radiography for detection of small defects in tooth, it will be useful in cases with difficulty for taking the intraoral radiographs. The aim of this study was to evaluate sensitivity and specificity of digital panoramic radiography for detection of proximal caries compared with the bitewing radiography.
Materials and Methods: One-hundred patients who had been ordered for taking both bitewing and panoramic radiography were included in this study. Panoramic and then bitewing radiographs were observed by a maxillofacial radiologist and interproximal caries were recorded. Sensitivity and specificity of digital panoramic radiography (CI=95%) was calculated compared with the bitewing radiography as a gold standard.
Results: This study showed that the values for sensitivity and specificity were 62.7% (CI 95%=57.7%-67.5%) and 91.0% (CI 95%=89.2%-92.5%), respectively.
Conclusion: Sensitivity of digital panoramic is less than bitewing radiography even with processing before printing. Therefore, bitewing radiography is superior for detection of inter proximal caries.

Background and Aims: The aim of this in vitro study was to compare shear bond strength of metal brackets bonded to dental porcelain on the basis of presence or absence of silane, type of acid [hydrofluoric acid (HF) or phosphoric acid (H3PO4)] and roughness of porcelain surface (glazed or deglazed) within mouth-like environment.
Materials and Methods: Eighty glazed ceramic disks were randomly divided into 8 groups of 10 disks: group 1 [HF+silane], group 2 [deglazed+HF+silane], group 3 [HF], group 4 [deglazed+HF], group 5 [H3PO4+silane], group 6 [deglazed+H3PO4+silane], group 7 [H3PO4], group 8 [deglazed+H3PO4]. Then the brackets were bonded and thermocycled. After that, shear bond strength test was done using the Zwick device and the type of bond failure was determined under stereomicroscope at 4X magnification. 3-way ANOVA and Kruskal-Wallis were used for statistical analyses.
Results: The shear bond strength for the test groups were as follows: group (1):13.05±7.7 MPa , group (2):25.16±10.66 MPa, group (3):6.7±5.86 MPa, group (4):15.39±8.97 MPa, group (5):12.76±7.91 MPa, group (6):13.57±7.85 MPa, group (7):0.54±0.67 MPa, group (8): 9.34±6.52 MPa. The type of bond failure in all groups was adhesive failure except for group 2. No significant difference in the interaction between (glazed or deglazed), (presence or absence of silane), and type of acid was found (P>0.05).
Conclusion: Under the conditions of this study, the best clinical method was the use of 37% phosphoric acid and silane that resulted in the optimal clinical strength and adhesive bond failure.

Background and Aims: Evaluation is a continuous process which is necessary for improvement of students learning and planning for required changes to obtain the educational objectives. The aim of the present study was to assess students' perspective on the achievement of the educational objectives of the Community Oral Health and Periodontology Departments using the CIPP model of evaluation.
Materials and Methods: A cross-sectional survey has been conducted using a questionnaire consists of four domains as introduced in the CIPP model of evaluation (Context, Input, Process and Product). Two groups of senior dental students of the dental school of Tehran University of Medical Sciences were approached. Data was collected anonymously and was analyzed with non-parametric Mann-Whitney test using the SPSS statistical package.
Results: The response rate was 67.7% for year 6 and 87.5% for the year 5 students. Respondents considered material presented in Periodontology Department more relevant and in need for their future career. However, teaching skills and motivation of the educators in Periodontology Department was considered inadequate. 67% of students reported having problem with material taught in Periodontology Department. Overall, significant difference in domains of Context and Process was observed between two departments (p<0.05). In the output domain students rated their clinical and theoretical ability "weak" in relation to splint, implant, management of acute gingivitis and electrosurgery compared with other topics which rated "good". Students considered their ability in using the principals of Evidence-Based Dentistry moderate.
Conclusion: The evaluation of the educational achievements of the two departments (COH and Periodontics) using CIPP model of evaluation showed that there is significant difference in two domains (Context and Process). In those topics which achievement was reported weak the revision of teaching methods is recommended.
Key Words: Education dental Program evaluation Self-evaluation

Fabrication of dental prosthesis for patients with microstomia has long been a problem for dentists. Microstomia is defined as an abnormally small oral orifice. Prosthetic rehabilitation of microstomia patients presents difficulties at all stages, from the preliminary impressions to fabrication of prosthesis. This study described a method for making impressions for patients with limited opening of the oral cavity which the use of a full-size impression tray was not possible.

Background and Aims: 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 isolate stem cells from mature human dental pulp and follicle and to determine their mesenchymal nature before differentiation based on the ISCT (International Society for Cellular Therapy) criteria.
Materials and Methods: In this experimental study, intact human third molars extracted due to prophylactic or orthodontic reasons were collected from patients aged 18-25. After tooth extraction, dental pulp and follicle were stored at 4°C in RPMI 1640 medium containing antibiotics. Dental pulp and follicle were prepared in a sterile condition and digested using an enzyme solution containing 4mg/ml collagenase I and dispase (ratio: 1:1). The cells were then cultivated in α-MEM medium. Passage-3 cells were analyzed by flow cytometry for the expression of CD34, CD45, CD 73, CD90 and CD105 surface markers.
Results: Dental pulp and follicle were observed to grow in colony forming units, mainly composed of a fibroblast-like cell population. Flow cytometry results showed that dental pulp and follicle are highly positive for CD73, CD90 and CD105 (mesenchymal stem cell markers) and are negative for hematopoietic markers such as CD34 and CD 45.
Conclusion: In this study we were able to successfully confirm that dental pulp and follicle stem cells isolated from permanent third molars have a mesenchymal nature before differentiation. Therefore, these two sources can be considered as an easy accessible source of mesenchymal stem cells for stem cell research and tissue engineering.

Background and Aims: The bond strength between veneer ceramics and zirconia frameworks is the weakest component in the layered ceramics. Due to the possible effect of adding pigments to the core materials on the bond strength between core and veneer as well as the introduction of new ceramic materials in dentistry, the aim of this study was to compare the zirconia core-veneer microtensile bond strength using two ceramic veneers with or without coloring the core.
Materials and Methods: In this experimental study, 12 disc-shaped specimens were fabricated using a manually aided design- manually aided manufactured (MAD/MAM) zirconia core (Zirkonzahn). Two veneering ceramics of Ceram Kiss and Zirkonzahn ICE were also used to veneer the specimens. Half of the Zirkonzahn discs were remained white and the others were colored by shade A2.Then, the discs were cut into microbars (30 for each group) and the microtensile bond strength of the core-veneer was calculated. The specimens were assessed using scanning electron microscopy (SEM) and the data were analyzed using two-way ANOVA and Student's t-test.
Results: Significant differences with respect to veneer layer were found (P<0.001). No significant differences were seen among colored and uncolored cores (P=0.69).
Conclusion: According to the apparent effect of veneering ceramics on the core-veneer bond strength, careful selection of these agents is essential to achieve adequate bond strength between core and veneer to prevent delaminating and chipping failures of zirconia veneered restorations.

Background and Aims: Relative displacement of the implant with respect to bone and quality of bone-implant contact play critical roles in the dental implant stability. The goal of this study was to investigate the dental implant stability using non-linear finite elements method. Therefore, bone-implant relative displacement due to applied force to the implant was calculated, and then an appropriate factor for defining quality of bone-implant contact was presented.
Materials and Methods: In order to develop a three dimensional model and compare the results with clinical studies, computed tomography (CT) scan data of a rabbit tibia was considered as a base. The model was exported to ABAQUS 6.9-1 to be analyzed using nonlinear finite elements method. Dynamic analysis was done on the model using the proper boundary condition and dynamic loads.
Results: Force-displacement curves in bone-implant interface were nonlinear. Friction coefficient, which is a criterion for implant stability and relative displacement, approximately became doubled as the vertical contact force was halved. However, the friction coefficient decreased with reduction of coulomb frictional coefficient.
Conclusion: Friction coefficient, which is calculated upon force-displacement curves, could be considered as a criterion to evaluate the dental implant stability. Decrease of the vertical contact force and also using rough surfaces improved the quality of bone-implant contact and stability of dental implant.

Background and Aims: The aim of this study was to evaluate the quality of an experimental hydrofluoric acid (HF) for preparation of porcelain and to compare it with two commercial hydrofluoric acids in Iranian trademark.

Materials and Methods: A- Evaluation of etch pattern of experimental HF using scanning electron microscope (SEM): 6 feldespathic discs were divided into 3 groups. Each group was etched with related HF (experimental, Ultradent and Kimia) for 1 minute. SEM images were recorded at 3 magnifications. B- Bond strength test: 18 feldespathic discs were considered for each acidic group. Then the porcelain surfaces were etched and bonded to composite with unfilled resin. Consequently, the microshear test was done. C- Microleakage test: 54 discs were divided into 3 groups (n=18). Then the porcelain surfaces were etched and bonded to composite with unfilled resin and finally observed under stereomicroscope. The data were analyzed with one-way ANOVA and Smirnov tests.

Results: SEM analysis showed no difference between groups in terms of etch pattern. Microshear bond strength values for experimental, Kimia, and Ultradent HF were 28.53 (±4.92), 28.21 (±6.61), and 26.14 (±7.61) MPa, respectively. There was no significant difference between the bond strength of test groups (P<0.05). Furthermore, no significant difference was found between the microleakage of test groups (P>0.05).

Conclusion: Quality of experimental HF in terms of etch pattern, microshear bond strength and microleakage of composite/porcelain interface was similar to that of two commercial hydrofluoric acids.

Background and Aims: Reliable bonding between tooth substrate and zirconia-based ceramic restorations is always of great importance. The laser might be useful for treatment of ceramic surfaces. The aim of the present study was to investigate the effect of laser irradiation on the shear bond strength of zirconia ceramic surface to dentin.

Materials and Methods: In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer Al2O3, CO₂ laser, or Nd:YAG laser in each test groups. After that, the specimens were cemented to human dentin with resin cement. The shear bond strength of ceramics to dentin was determined and failure mode of each specimen was analyzed by stereo-microscope and SEM investigations. The data were statistically analyzed by one-way analysis of variance and Tukey multiple comparisons. The surface morphology of one specimen from each group was investigated under SEM.

Results: The mean shear bond strength of zirconia ceramic to dentin was 7.79±3.03, 9.85±4.69, 14.92±4.48 MPa for CO₂ irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO₂ (P=0.001) and Nd:YAG laser (P=0.017) irradiated specimens with sandblasted specimens. No significant differences were observed between two laser methods (P=0.47). The mode of bond failure was predominantly adhesive in test groups (CO₂ irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting: 41.7%).

Conclusion: Under the limitations of the present study, surface treatment of zirconia ceramics using CO₂ and Nd:YAG lasers was not able to produce adequate bond strength with dentin surfaces in comparison to sandblasting technique. Therefore, the use of lasers with the mentioned parameters may not be recommended for the surface treatment of Cercon ceramics.

Background and Aims: The present study aimed to evaluate the barriers to the production of scientific dental articles in dental schools in Iran based on the opinions of dental postgraduate students.

Materials and Methods: A self-administered questionnaire was distributed among postgraduate students of all Iranian dental schools in June 2010. The respondents rated their agreement with eight sentences about what hinder them from producing scientific dental articles based on a 5-grade Likert scale. The data were analyzed using Chi-square test.

Results: Totally, 270 filled questionnaires from 14 dental schools were received. Of all respondents, 53% were male, the mean age were 29.6 ± 3.8. About half of the respondents reported at least one published article. Less than half of the respondents reported producing an article from undergraduate thesis more women than men and more younger than older students (P<0.03). About two-third of the respondents rated absence of an English editing center, no financial incentives, no appropriate environment, and no competency for scientific writing as most prevalent barriers to the production of scientific dental articles.

Conclusion: To expand the share of Iran in the production of scientific dental documents, the potential of postgraduate dental students must be regarded and suitable condition for scientific writing must be provided. Specifically, based on the findings of the present study, provision of an English editing facility, establishing financial incentives, and providing the students with appropriate environment and efficient scientific writing education are of utmost importance.

Dentistry has been a field dominated by a constant improvement of synthetic biomaterials. Tissue engineering of tooth is coming to change the panel of the dental materials such as restorative materials and implants. Certainly, it is the largest transition in history of dental materials science in terms of accepting this new and exciting technology. The objective of this article is to present various implications of tissue engineering in different fields of dentistry. To achieve this goal, a review of the literature was carried out by using Medline database to search topics including "dental stem cells", "teeth tissue engineering", "regenerative dentistry", "oral surgery", "periodontal regeneration" and "regenerative endodontics". These searches were limited to articles published after the year 2000. On the basis of our literature review, we have found that although there are significant challenges in oral tissues engineering, engineered tissues will find many applications in dentistry within the next few years.

Background and Aims: The aim of this study was to investigate the prevalence of diabetes and other risk factors in patients with dental infections.

Materials and Methods: A cross-sectional study was conducted among 50 patients who preferred in maxillofacial word of shariaty hospital with acute dental infections in 9 months. A self-administered questionnaire was administered during a dental appointment in order to gather demographic information and recorded past history of systemic disease, OPG radiography, gingival examination, and the result of lab tests such as CBC , FBS , PT, Bilirubin , Creat, T3, T4, TSH, HIVAb and HBSAg.

Results: 28% of the subjects and diabetes, 28% Anemia, 4% Hepatitis and 4% suffered from thyroid deficiency. 28% were smokers and 18% declared using alcohol. 6% of this population was addicted to narcotic substances. There was a significant correlation between age, education, diabetes and dental infections (P<0.05). DMFT for people with dental infections without any systemic disease were 8, for diabetic patients, smokers and alcohol users were respectively 17.16, 17 and 14.

Conclusion: Diabetes found highly prevalent in patients with dental infection and high DMFT.It indicates a need to establish a comprehensive oral health promotion program based on whole examination and blood glucose control in diabetic patients who have acute dental infection by collaboration between dental and general health care professionals. Moreover, it is recommended that all patients should be educated in dental and oral health for prevention of dental infections.

Background and Aims: Nursing Caries (NC) is a destructive form of caries because of incorrect nutritional habits in infants that affects deciduous teeth after eruption. Familiarity with the pattern of this type of caries and evaluation of its symmetrical or asymmetrical pattern is necessary for effective and scientific diagnosis and treatment. The aim was to assess the symmetrical or asymmetrical aspects of Nursing Caries in children between 3-5 years old.

Materials and Methods: In this cross-sectional study, 10 kindergartens were randomly selected by the Tehran Welfare Organization. 115 children with NC caries entered to study after examination. Written consents were obtained from the parents. The dmfs in upper primary incisors and upper and lower primary canines, as well as the first primary molars were assessed and the caries pattern in terms of symmetrical or asymmetrical aspects was evaluated. The data were analyzed by ANOVA, LSD, Chi-square and Fisher tests.

Results: In 53.9% of the children with NC, the anterior teeth were affected symmetrically, while 46.1% indicated an asymmetrical pattern. In general, 32.2% of the teeth were affected in a symmetrical pattern and 67.8% of them in an asymmetrical pattern. About the relationship between the breastfeeding from the right or left breast and the symmetrical pattern of the NC, 51% of the children were equally breastfed from both breasts. However, in the asymmetrical NC pattern with more impact in the right side of dentition, 50% of the children had been breastfed from the left side and in children with more caries  in the left side of dentition, 50% of them had been breastfed from the right side (P=0.01).

Conclusion: NC has symmetrical and asymmetrical patterns. Direction of mother for breastfeeding affects the symmetrical and asymmetrical pattern of NC.

Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS), which is a Tapered Interference Fit (TIF) with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.

Materials and Methods: Relevant equations were developed to predict tightening and loosening torques, contact pressure and preloads with and without bone tissue in this analysis. The efficiency is defined as the ratio of the loosening torque to the tightening torque. The effects of the change in elastic modulus and thickness of the bone on operation of this mechanism were investigated.

Results: In this study, 14 independent parameters such as taper angle, friction coefficient, abutment and implant geometry that are effective on performance of TIS mechanism were presented. The role of some factors was shown in the performance of ITI implant using sensitivity analysis.

Conclusion: It was shown that friction coefficient, contact length, and implant radius play major roles on tightening and loosening torques and efficiency of the mechanism. Furthermore, the results revealed that the change in the elastic modulus and thickness of the bone influenced the efficiency of the mechanism less than 15%.