مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال بیست و هفتم شماره 1 (پیاپی 78، بهار 1393)

The increase in the number of complex implant cases has drawn the attention of researchers toward materials having bone regeneration promoting ability. Socket preservation and bone graft are recommended to minimize bone resorption. The aim of this study was to evaluate a kind of xenograft collagenic bone (osteo biol gen_oss) in socket regeneration. This randomized clinical trial was performed in 12 cases (6 in test and 6 in control groups) with two hopeless teeth. After tooth extraction، in test group، graft material was put in sockets but in the control group the socket was healed naturally. Three months later، during implant placement the specimens from both sites were sent to a pathologist for histologic and histomorphometric evaluations. Data were analyzed using Mc Nemar and Wilcoxan sigh rank test (α=0. 05). There were no significant differences between two groups in foreign body reaction، inflammation، bone vitality and percentage of bone gain. Average percentage of residual graft in test site was 6. 73±1. 43. Osteobiol gen_oss xenograft is an appropriate biocompatible osteoconductive material that promotes bone regeneration at 3 months following socket preservation in human extraction sockets.

Antibiotics are commonly used for controlling the growth of porphyromons gingivalis (P. g) which is one of the most important etiologic factors in the periodontal diseases. Different side effects of synthetics and chemical drugs such as increasing the drug resistancy in the human pathogens have led to study on the herbal antibacterial effect. The aim of this study was to evaluate the antibacterial effect of cinnamon on the growth of porphyromons gingivalis in chronic periodontitis patients with deep pockets. In this experimental study، samples were provided from patients having pockets. After culturing the microorganism and diagnosis of P. g by gram staining and biochemical tests، cinnamon in different concentrations (10، 50، 100، 250، 500، 750 and 1500 mg/ml) with oil solvent were prepared and placed by disks in the cultures medium. Positive controls were amoxicillin، metronidazole، ciprofloxacin، amikacin and gentamycin. Oil was negative control. Then the plates were incubated for 24 hours in 37 0 C and then non-growth halos by disk diffusion method، MIC (Minimum Inhibitory Concentration) and MBC (Minimum Bactericidal Concentration) were determined. Data were analyzed using One-way ANOVA test. The results showed that the cinnamon at the concentration of MIC=750 mg/ml had the inhibitory effects of bacteria and at the concentration of MIC=1500 mg/ml had killing effect. However، this antibacterial effect compared with commonly used antibiotics (amoxicillin، metronidazole)، was much weaker (P<0. 001). Cinnamon showed an antimicrobial effect on porphyromonas gingivalis in chronic periodontitis patients with deep pockets.

Since recurrent caries are one of the major causes of failure in resin restorations، the production of antibacterial resin composites was always under investigation. The aim of this study was to evaluate the efficacy of fissure sealants containing nanosilver particles against the Streptococcus mutans. In this experimental study، the antibacterial properties of two sealants (with fluoride (Clinpro 3M) and without fluoride (Concise 3M) was investigated with 0، 0. 01، 0. 02، 0. 03، 0. 04، 0. 05% w/w after adding nano-silver using direct contact test. Sealants formed on the walls of 500ml micro tube and after curing، they left in contact with bacterial suspension. In periods of 3، 24، 48h، a 10 µl volume of liquid medium was placed in blood agar culture and after 24 h incubation at 37ºC، the number of S. mutans colony was counted by colony counter. Data were analyzed using ANOVA and T-test. Results reported sealants with fluoride comparing to non fluoride ones had significant effect on inhibition of S. mutans growth (P<0. 001). The direct contact test demonstrated that by increasing the amount of nano particles، the bacterial growth was significantly diminished (P<0. 001). While sealants with fluoride demonstrated antibacterial effect، sealants with incorporation of higher weight percentage of nanosilver particles، had stronger and more significant antibacterial effect in direct contact test.

The root fracture resistance of endodontically treated teeth depends on the types of posts. The aim of this study was to compare the effect of two types of bonded non-metallic posts with different elasticity modulus on the fracture resistance of endodontically treated teeth under compressive loads. In this in vitro experimental study، 20 fresh extracted mandibular premolars were selected and sectioned adjacent to the CEJ and then were endodontically treated. The specimens were randomly divided into two groups (n=10). After post space preparations، the fiber RTD Light posts (R. T. D، France) and zirconia coated fiber posts (ICE light، Danville) were cemented into the root canals. Composite resin (Lumiglass R. T. D، France) cores were built up. Aluminium foil was used to mimic the PDL، and the specimens were embedded in acrylic resin and tested in a Universal Testing Machine. A compressive load was applied at a 90 degree angle until fracture at a crosshead speed of 1mm/min. Data were analyzed using one-way ANOVA and T test. The mean fracture resistance of R. T. D group was (1083. 11 ± 156. 74 (N)) and the mean of ICE light group was (865. 18 ± 106. 24 (N)). The highest mean fracture resistance was observed in RTD fiberglass and a statistically significant difference was observed between the two groups (P<0. 001). FRC posts with zirconia coating due to unfavorable fractures of the teeth should be used with caution، and thus، fiber posts are preferred.

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 Er; YAG laser compared with sandblasting. On the micro tensil bond strength of resin cement to indirect composites. 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. 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). 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.

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.

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).

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).

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.

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

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. 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. 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.

Author (s): 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. 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. 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). 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.

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.

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.

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).

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.