Journal of Dental Medicine

  Background and Aims: Indirect composites are designed to overcome the shortcomings of direct composites such as polymerization shrinkage and low degree of conversion. But, good adhesion of resin cements to indirect composites is still difficult. This research was designed to assess the effect of different powers of ErYAG laser compared with sandblasting. On the micro tensil bond strength of resin cement to indirect composites.

  Materials and Methods: Specimens were prepred using dental resin composite (Gradia GC) and metallic mold (15×5×5 mm) and were cured according to the manufacturer’s instructions. 24 blocks were prepared and randomly divided into 12 groups. G1:no treatment (as control), G 2-6: Er YAG laser irradiation (2, 3, 4, 5, 6 Watt), G7: sandblast. Two composite blocks were bonded to each other with Panavia F.2. resin cement. The cylindrical sections with dimensions of 1 mm were tested in a microtensile bond strength tester device using 0.5 mm/min speed until fracture points. Data were analyzed using 2-way ANOVA and T-test.

  Results: Interaction between lasers irradiation and sandblast treatments were significant (P<0.05). Thus, T-test was used for comparing laser groups. T-test showed that when using laser with energies less than 150 mJ, there was no significant difference (P>0.05) whether samples were sandblasted or not. Samples which received 300 mJ of laser showed lower bond strength compared with no laser treatment. Other groups showed no significant difference (P>0.05).

  Conclusion: It seems that application of sandblast with proper variables, is a good way to improve bond strength.
Laser application had no influence in improving the bond strength between the indirect composite and resin cement.

  Background and Aims : In this in vitro study, the long-term bond strength of a self-adhesive resin cement and conventional resin cements to human enamel and dentin was compared .

  Materials and Methods: 80 sections of intact human third molars were randomly assigned into eight groups according to the cement type [Rely X Unicem (RXU), Rely X ARC (RXA)], bond substrate (enamel, dentin) and the duration of water storage (24 h or 1 year). Rods of cements (0.75×1 mm) were prepared on the top surface of specimens using Tygon tubes. The micro-shear bond strengths of specimens were measured by a micro-tensile tester. Data were analyzed using Wilcoxon signed ranks and Mann Whitney tests ( α =0.05).

  Results: The bond strengths of RXA and RXU cements to enamel after 24h were 18.56±4.08 MPa and 14.99±4.17 MPa, and after 1 year were 19.41±6.24 MPa and 15.51±6.17 MPa, respectively. The bond strengths of RXA and RXU cements to dentin were 13.36±4.02 MPa and 14.16±4.69 MPa after 24h , and 14.63±5.96 MPa and 14.08±6.72 MPa after 1 year, respectively. Tooth substrate had significant effect only on the shear bond strength of RXA cement after 24h (P=0.01), while no other significant differences were found in this study (P>0.05).

  Conclusion: According to the results of this study, one-step self-adhesive and multi-step conventional resin cements were similarly effective in bonding to enamel and dentin after 1 year water storage.

  Background and Aims: Nowadays, the application of all ceramic restorations are being raised, because of their physical characteristics, such as translucency and good appearance. Numerous researchers investigated the impact of surface treatments on the bond strength of zirconia ceramic with resin cements. The aim of this study was to compare the microshear bond strength of Cercon and Zirkonzahn (two kind of zirconia) ceramics, to two types of resin cements after thermocycling.

  Materials and Methods: In this study, 24 rectangular specimens were made from each group of Cercon and Zirkonzahn ceramics. After sandblasting, these specimens were connected to 3×1 mm² composite cylinders by two resin cements (Panavia F₂ and Rely X Unicem₂). After performing a thermocycling regime for 5000 cycles (5-55 ◦ C), the microshear bond strengths were measured by a universal testing machine. The mode of failures were determined by a stereomicroscope. Data were analyzed using two-way ANOVA.

  Results: Type of ceramics had no significant impact on the microshear bond strength (P=0.317). The highest bond strengths in both ceramics were obtained with Reply X Unicem (P=0.035). The predominant failure mode was adhesive between the cement and ceramic.

  Conclusion: Type of resin cement had a significant effect on their bond strengths to zirconia ceramics.

  Background and Aims: Classification is a fundamental issue in quantitative studies of any phenomenon and has been known as a necessity for the advancement of science. Using a standard record system for diseases is critical for research purposes and also could improve the quality of medical health services. In this study, after evaluating current codding systems in oral medicine, we designed a software for systematic coding and registration of Oral and Maxillofacial diseases based on the latest update of the World Health Organization ICD-10 classification system in 2010.

  Materials and Methods: Based on the latest WHO ICD-10 update in 2010 and by using software s as: vb.net, net framework, SQL Server and Microsoft Visual Studio, standard coding software for recording patient's data at the department of Oral Medicine, School of Dentistry, Tehran University of Medical Sciences was designed. Data from all patients were codded by standard ICD-10 codes and registered by the software. Also an online portal for recording patient's data which could be used nationwide was designed. By d esigning this software the process of forming and registering patient's records, and their treatment process is facilitated . An archive of patient data was also stablished .

  Conclusion: As a result , this software in addition to maintaining patient data , facilitate studies and research projects greatly. It’s recommended that the Iranian Ministry of Health and Medical Education as the concessioner of this software, improves codding and registration systems of oral diseases at the dental schools by developing this software.

  Background and Aims : Dentists have usually a critical role in diagnosing oral cancer lesions in their early stages. In this study we aimed to assess the senior dental student’ and dentists’ knowledge, attitude and behaviors regarding oral cancer in Isfahan.

  Materials and Methods: A valid and reliable self-administered questionnaire was designed to assess the current practice, knowledge and attitude of general dentists working in Isfahan-Iran and senior dental students regarding oral cancer lesions. The questionnaire was consisted of questions to assess the knowledge and attitude regarding diagnosis, risk factors and prognosis of oropharyngeal cancerous lesions. The frequencies of answers to questions in sections of practice and attitude (just for dentists) and sum score of questions in knowledge section were calculated and compared using statistical analysis regarding age, sex, duration of experience and practice setting ) p ublic/private) of participants. Data were analyzed using ANOVA, chi-square, linear regression and logistic regression.

  Results: 139 questionnaires from dentists and 57 questionnaires from students were returned. The mean score of dentists’ knowledge was 5.41 out of 13 (CI95%=5.03-7.79 ). Significant differences were observed among dentists regarding their experience (P=0.001). Only one fifth of the dentists in our survey reported to perform oral cancer examination for all of their patients in age of 40 and above and just about 34% of dentists gained acceptable level of knowledge. Among senior dental students, the status of knowledge was better as about 58% of them gained the level of acceptance (P=0.01).

  Conclusion: Although dentists were willing to follow the diagnostic protocol for oral cancer, they were mostly unsatisfied with the level of their knowledge. Therefore, this study highlights the need for educational planning and training activities in general dentists with regard to the risk factors and early detection of oral cancers.

  Background and Aims : Free gingival graft is one of the most predictable procedures for gingival augmentation, but patient’s discomfort and pain during healing period of palatal donor site is a significant concern. The aim of this study was to evaluate the effect of 660nm low power laser on pain and healing in palatal donor sites.

  Materials and Methods: The present split mouth randomized controlled clinical trial was performed in 12 patients at the department of periodontics of Tehran University of Medical Sciences. Patients’ allocation was done by balanced block randomization (laser group and placebo group). In laser test group (wave length: 660 nm, power: 200mW, time of irradiation: 32s) was applied immediately post-surgery and in day 1, 2, 4 and 7 after that. In the control group, laser application was done with off power mode. Evaluation of epithelialization and healing was done with H₂O₂ and photograph. The number of palliative pills and bleeding was recorded. Wilcoxon test was used to analyze healing during the study. Patient’s pain during study was analyzed using repeated measure ANOVA. Mc Nemar test was used to analyze bleeding. Level of statistical significance was set at 0.05.

  Results: Laser group showed better epithelialization (P=0.02) and healing (P=0.01) in day 14 after surgery and showed better epithelialization in day 21(P=0.05). No statistically differences were observed between laser group and control group in terms of bleeding and medication (P=0.51), (P=1).

  Conclusion: According to the results of this study, the low power laser can promote palatal wound healing during the second and third week after free gingival graft procedures.

  Morality and ethics constitute fundamental principles of professional, educational and investigational aspects of medicine and all its branches, including dentistry. There are specific considerations in dental research which could significantly affect the design and progress of scientific projects performed in this field. The aim of the current study was to present an overview of ethical concepts governing dental research and to provide examples of common issues raised during dentistry-related investigations. Establishment of human tooth banks in major research and training centers is suggested to enhance the process of conducting more substantial research in dentistry.

  Background and Aims: Orthodontic patients’ cooperation is a determining factor in treatment outcomes. The aim of this study was to evaluate the relationship between patient cooperation during orthodontic treatment with variables such as age, sex, life setting, treatment duration and functional and social discomfort experienced.

  Materials and Methods: Specimens were consisted of 100 orthodontic patients (36 males and 64 females) between 13-35 years old (average age: 22.57±1.69 years). Patients’ demographic traits, treatment duration and
functional-social discomfort by the orthodontic treatment were evaluated using a questionnaire answered by the patients or their parents. The degree of patient cooperation was assessed by the modified cooperation questionnaire (Orthodontic Patient Cooperation Scale [OPCS]) which was completed by an orthodontist. Data were analyzed using One-way ANOVA, T-test, intraclass correlation coefficient and Pearson Correlation.

  Results: No significant difference was found between the cooperation of male and female patients (P=0.867) and also between the cooperation of the patients who lived in the urban and rural setting (P=0.613). Treatment duration and compliance showed a low negative correlation which was not statistically significant (r=-0.155, P=0.127). Functional-social discomfort and compliance showed a low negative correlation which was not statistically significant (r=-0.118, P=0.244). No significant correlations were found between the compliance and age (r=0.002, P=0.988) and also the treatment duration and functional-social discomfort experienced
(r=0.164, P=0.105).

  Conclusion: Patient compliance appears to be a complex issue that cannot easily be predicted only by factors such as age, gender, life setting, treatment duration and functional-social discomfort experienced.

  Background and Aims: Hydroxyapatite coating has allocated a special place in dentistry due to its biocompatibility and bioactivity. The purpose of this study was to evaluate the relation between the hydroxyapatite thickness and stress distribution by using finite element method.

  Materials and Methods: In this paper, the effect of hydroxyapatite coating thickness on dental implants was studied using finite element method in the range between 0 to 200 microns. A 3D model including one section of mandible bone was modeled by a thick layer of cortical surrounding dense cancellous and a Nobel Biocare commercial brand dental implant was simulated and analyzed under static load in the Abaqus software.

  Results The diagram of maximum von Mises stress versus coating thickness was plotted for the cancellous and cortical bones in the range between 0 to 200 microns. The obtained results showed that the magnitude of maximum von Mises stress of bone decreased as the hydroxyapatite coating thickness increased. Also, the thickness of coating exhibited smoother stress distribution and milder variations of maximum von Mises stress in a range between 60 to 120 microns.

  Conclusion: In present study, the stress was decreased in the mandible bone where hydroxyapatite coating was used. This stress reduction leads to a faster stabilization and fixation of implant in the mandible bone. Using hydroxyapatite coating as a biocompatible and bioactive material could play an important role in bone formation of implant- bone interface.

  Background and Aims: The aim of this study was to evaluate the fracture strength of restored teeth with three different types of E glass-fiber posts after thermo-mechanical loading.

  Materials and Methods: Sixty extracted upper central incisor human teeth, with similar size, were selected and divided into three groups (n=20). Endodontic treatment was done in all groups and crowns were sectioned from 2 mm above CEJ. Then one type of posts in each group (Anthogyr, Svensk, Hetco) cemented using Panavia cement and the crowns were restored with a composite. The specimens in each group were thermocycled for 6000 cycles (5-55°C) and subjected to 1200000 cycles of mechanical loadiong in an artificial mouth machine. Then the fracture strength was measured and data were analyzed using ANOVA and T-student test (α=0.05).

  Results: The mean fracture strengths in Hetco group before and after thermomechnical loading were 581.098 ± 192.742 N and 564.74±213.59 N, in Anthogyr group were 664.358 ± 135.878 N and 629.12±390.3 N and, in Svensk group were 780.258 ± 379.133 N and 779.84±282.59 N, respectively. There was no significant difference between groups and also there was no significant difference in each group before and after thermo-mechanical loading (P>0.05).

  Conclusion: Restored teeth with Hetco fiber glass post were similar in terms of the fracture strength with that of two other posts after thermo-mechnical loading.

  Background and Aims Bone density is frequently used in medical diagnosis and research. The current methods for determining bone density are expensive and not easily available in dental clinics. The aim of this study was to design and evaluate the accuracy of a digital method for hard tissue densitometry which could be applied on personal computers.

  Materials and Methods: An aluminum step wedge was constructed. 50 E-speed Kodak films were exposed. Exposure time varied from 0.05s to 0.5 s with 0.05 s interval. Films were developed with automatic developer and fixer and digitized with 1240U photo Epson scanner. Images were cropped at 10 × 10mm size with Microsoft Office Picture Manager. By running the algorithm designed in MATLAB software, the mean pixel value of pictures was calculated.

  Results: Finding of this study showed that by increasing the exposure time, the mean pixel value was decreased and at step 12, a significant discrimination was seen between the two subsequent times(P<0.001). By increasing the thickness of object, algorithm could define the density changes from step 4 in 0.3 s and 5 in 0.5 s, and it could determine the differences in the mean pixel value between the same steps of 0.3 s and 0.5 s from step 4.

  Conclusion: By increasing the object thickness and exposure time, the accuracy of the algorithm for recognizing changes in density was increased. This software was able to determine the radiographic density changes of aluminum step wedge with at least 4mm thickness at exposure time of 0.3 s and 5 mm at 0.5 s.

  Background and Aims: The ability of composite restorations to prevent microleakage needs desirable bonding material for proper sealing . The purpose of this study was to evaluate class V composite restorations microleakage in premolars with/without electric current while applying variant dentin bonding in vitro.

  Materials and Methods: 120 non-carious human premolars were used for this study and standardized class v cavities were prepared. The tooth roots were cut by discs at a distance of 5 mm from CEJ and pulp tissue was removed. The teeth were divided into six groups of 20. In the first group, electric current was applied, Single bond (3M ESPE, St Paul, MN, USA) with a broom motion attached to the cathode and a sponge containing bonding was used as anode. The used current was 15µA and the Single bond in the second group was used without electricity. Then two bondings PQ1 (Ultradent, Germany) and Optibond solo plus (Kerr, USA) were used with and without electricity. After adhesive application and curing the bonding agents, cavities were restored by a composite (Valux Plus). The root ends were sealed by wax and all teeth surfaces, except 1 mm around the restorations were covered with a nail varnish. The specimens were thermocycled for 1000 cycles and placed in fushin for 24 hours and were then sectioned vertically and examined under a stereomicroscope. Data were scored on a 0-4 scale based on microleakage at the gingival margins and analyzed using Kruskal-Wallis and Mann-whitney test.

  Results: Based on the results, the extent of microleakage in the groups of electric current was significantly less than the groups without using the electric current (P=0.05). The lowest degree of microleakage was found in PQ1 group, and the greatest difference between the groups with and without electricity was also found in PQ1 group. Single bond and Optibond Solo Plus with electric current showed a lower degree of microleakge.

  Conclusion: The result showed that use of electric current during the application of dental adhesives could reduce the extent of microleakage.

  Background and Aims: It is crucial to verify the relationship between root apices and maxillary sinus floor in some surgical procedures like extraction and implant placement or in orthodontic movements like intrusion. Protrusion of roots into the sinus increases the risk of post extraction pneumatization which in turn decreases the available bone at the implant or denture sites. The aim of this study was to determine the panoramic radiology accuracy for defining the relationship between posterior root apices and the maxillary sinus floor by Cone Beam CT (CBCT).

  Materials and Methods: Paired panoramic radiographs and CBCT images of 117 subjects were examined. 452 posterior maxillary roots including second premolar, first and second molar were classified by the means of the relationship with maxillary sinus floor. CBCT was used as Gold standard method, and the agreement of panoramic findings with CBCT was examined statistically. Data were analyzed using Chi-square and Multiple logistic regressions.

  Results: Agreement of the panoramic and CBCT results were seen in 57.7% of all cases. Roots which had no contacts with the sinus floor (class 0) showed a high agreement of 89.5% between two imaging techniques. Roots in contact with sinus floor (class 1) showed 58.8 % and cases with root protrusion into sinus cavity (class 3, 4) showed 50% of agreement (P<0.001). Also in 36% of cases with no protrusion into the sinus cavity (class 0, 1, 2), panoramic showed protrusion. The agreement for the premolar was higher than molars (P<0.001)

  Conclusion: The majority of roots which their images were projected on the sinus cavity had no vertical protrusion in CBCT cuts. Considering the results, in these cases CBCT can be recommended.

  Background and Aims: Electric pulp tester is a valuable instrument to examine tooth’s pulp vitality. There is no agreement about the response of immature teeth to electric pulp tester and the reason is expressed as the failure of nerve fibers’ development. The aim of this study was to investigate the effect of patient’s age on the tooth response to electric pulp tester.

  Materials and Methods: In this cross-sectional study, 300 maxillary central permanent teeth in 150 volunteers were examined by using electric pulp tester. The volunteers were classified in 5 age groups of 7-8, 9-10, 11-12, 13-4, and 30-35 and teeth lacking sound and healthy pulp were excluded. Data were analyzed using SPSS-16 software, one-way analysis of variance, and Tukey post hoc test.

  Results: The average response to electric pulp tester in age groups of 7-8, 9-10, 11-12, 13-4, and 30-35 years old were 2.9±0.1, 2.8±0.1, 2.3±0.1, 2.2±0.1 and 1.8±0.1 ,respectively. This indicated that by increasing teeth age, they responded to lower level of electric pulp tester. In subjects less than 14 years old, there was no significant difference between neighboring groups (P=0.3) however, a significant difference was observed between subjects less than 14 years old and adults (P<0.001).

  Conclusion: This study showed that immature teeth responded at higher levels to electric test however, all teeth responded to electric pulp tester.

  Background and Aims: Root canal therapy is one of the most important parts of a general dentist's profession. The aim of this study was to evaluate the radiographic quality of root canal therapy performed by under graduated students at Yazd dental school.

  Materials and Methods: Records of patients, who were referred to the endodontic department during 2010-2012 and treated by undergraduated students, were divided into three groups by the numbers of canals and 80 specimens from each group were randomly evaluated. For the assessment, the quality of accomplished treatments, the indices: length, taper, and density of obturation were used and the errors during root treatment were recorded. Data were analyzed using Fisher's exact test and Chi-square.

  Results: According to the results, 155 (64.6%) records had appropriate filling length, whereas 55 (22.9%) were underfilled and 30 (12.5%) were overfilled. The acquired difference was statistically significant among three groups. (P<0.001). 187 (77.9%) records had adequate taper and 157 (65.4%) records had adequate density. The difference in the evaluating of taper (P=0.976) and density (P=0.879) was not significant. Totally, 39.2% of specimens had all the properties of an appropriate root canal treatment.

  Conclusion: The results of the present study can be used to identify weaknesses in the treatment of different educational groups and help them to achieve a proper planning to improve the quality of endodontic treatments.

  The need to identify and determine the age of the unidentified dead person s or accident victims of natural disasters is clear. Also, some remedial measures in the field of orthodontics and pediatric dentistry depend on knowing the patient’s physiological age. Previous studies suggested that dental age have a good correlation with physiological age more than skeletal or o ther common methods of age determination. Among the various methods used to determine dental age , dental radiography provides wide facilities for clinicians. Being noninvasive and the ability of performing the technique on live subjects as well as simplicity and low cost and reliable results , have led researchers to investigate further on that . The formation and calcification process of teeth and changes during aging has been regarded by many, leading to introduce various methods in which the field. In this study, 36 related articles were achieved by searching PUBMED, Science Direct and Google Scholar resources and discussed. Provided what diversified means of determining age using dental radiographs is encouraged , it is recommended to be not restricted to use only one of the methods because the multilateral approach is more reliable.

  Background and Aims: The aim of this review article was to present the information have been published, regarding the functional properties of Zirconia until today.

  Materials and Methods: 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.

  Conclusion: 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.

  Background and Aims: 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).

  Materials and Methods: 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.

  Results: 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).

  Conclusion: 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.

  Background and Aims: 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.

  Materials and Methods: 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.

  Results: 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).

  Conclusion: Thyme essence could be considered as a natural irrigator with a comparable antiseptic effect to sodium hypochlorite.

  Background and Aims: 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.

  Materials and Methods: 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.

  Results: 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).

  Conclusion: 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.