Vol 1, No 2 (2004)
Proceeding Abstracts
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Statement of Problem: Although no minimum width of attached gingiva has been established as a standard for gingival health; gingival augmentation has been carried out because of many reasons. There are numerous methods for widening keratinized attached gingiva. Purpose: This study is to present "Vertical Strip Gingival Graft Technique" as an attempt to improve methods of gingival augmentation. Materials and Methods: In a before-after clinical trial 12 systematically healthy patients with no attached gingiva more than 0.5mm in at least 3 adjacent teeth were entered the study. After recipient bed preparation and harvesting free gingival graft (FGG), the graft was divided in two pieces and each part was fixed in one end of the bed. In this method an area with mean width of 6mm of recipient area, between two grafts, was remained uncovered. In order to determine the efficiency of this technique to augment attached gingiva the distance between stent to mucogingival line (MGL) and widths of attached gingival were used as indicator parameters. Clinical Parameters were measured using Wilcoxon sign rank test before surgery, 6 and 12 weeks after operation. Results: The mean value of stent to MGL in the middle part (between FGGs) at the baseline, 6 and 12 weeks after operation were: 7.82±2.61mm, 11.53±1.4mm, 11.23±1.1mm respectively. The mean width of attached gingiva in those sites at the same intervals was as follows: 0.3±0.2mm, 3.72±1.31mm, and 3.41±1.06mm. Results showed significant increase in the width of attached gingiva (P<0.01). The mean distance of stent to MGL between baseline and 6 week's data; and baseline and 12 week's also showed significant changes (P=0.001). Conclusion: With respect to the limitation of this study, by application of "vertical strip gingival graft technique" wider recipient site with less donor tissue can gain keratinized coverage. And as a result of producing smaller wound in the donor site (palate), patients would have less post surgical pain and discomfort.
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Statement of Problem: A recent technique (MBT) has been introduced for easy and efficient orthodontic treatment by means of straight wire fixed appliances. Although this technique has many advantages, in space closure stage causes up righting problem in upper incisors, which should be adjusted by applying additional torque in anterior region. Purpose: The purpose of this clinical trial was to determine whether there is a significant difference in final incisor inclination (torque) of two groups one treated with MBT technique and the other by changing the point of application of the closing force (in anterior region). Materials and Methods: Twelve patients (8 girls, 4 boys) with Cl I malocclusion and crowding, whom were candidate for first premolars extraction, were selected. For space closure, 6 anterior teeth (canine to canine) in upper and lower jaws ligated and the applied force was from the hooks on canines to hooks on the first molars. After space closure the results compared with the results of a previous study which treatment plan was according to original MBT technique (anterior hooks soldered to arch wire). Forces applied randomly among quadrants by NiTi coil spring (American Orthodontics Co.) or active tie backs with elastic modules (Dentaurum Co.) Results: The results showed a statistically significant difference between final torques of two techniques (P=0.0001). Also, the rate of space closure with NiTi coils was significantly greater than active tie back (P=0.0001). Conclusion: Anchorage loss in two groups compared and the results indicated significantly lower anchorage loss in NiTi coil spring group (P=0.035).
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Statement of Problem: Currently there are three recognized theories about the diameter of prepared dowel space in endodontically treated teeth. Diameter of the dowel is commonly contributed to the root fracture. Purpose: This study used a 3 dimensional (3D) finite element method to predict stress distribution in endodontically treated central maxillary tooth with cast post and core with various post diameter according to three philosophies about post diameter (Conservational, Proportional, Preservational). Materials and Methods: In this study three 3D models of central maxillary incisors with different post diameter were created and depend on the size of post called narrow, medium and thick model with post diameter of 1.1mm, 1.7 mm and 2.6 mm of in (CEJ) respectively. A load of 100 N was applied to cingulum fossa from lingual direction with 45-degree angle to long axis of tooth and maximum tensile, compressive and Von Misses stresses and their distribution in dentin and post was studied. Results: The post in narrow, medium and thick models produced a similar magnitude of tensile, compressive and Von Misses stresses in dentin. Stress distribution was also similar in all models. Peak stresses in dentin were slightly decreased when post diameter increased from narrow to thick model. In all models peak tensile stresses in dentin occurred in the coronally one third of the lingual surface of the root, whereas peak compressive stresses were evident in the coronal one third of the facial surface of the root. Conclusion: There were not significant differences stress distribution pattern and magnitude in dentin between the three theories of post diameter
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Statement of Problem: The elimination of Actinobacillus actinomycetemcomitans (A.a) is a key factor for achieving a successful treatment in patients with aggressive periodontitis (AgP) whom harboring this organism. This micro organism’s capability to invade to host’s tissues, makes its eradication with mechanical therapy (eg. flap surgery, scaling, oral hygiene) very difficult, so there is no other way than using a systemic antibiotic. But which antibiotic is the best one? The Ciprofloxacin is the only antibiotic which can suppress all strains of A.a. Purpose: The aim of this study was to compare the effectiveness of Ciprofloxacin in elimination of A.a in active sites of AgP patients with combination of Metronidazole and Amoxicillin. Materials and Methods: This study was a randomized double blind controlled clinical trial. Twenty four patients with clinical diagnosis of AgP and detection of A.a in their pockets were randomly divided into two groups. The 12 patients in test group received Ciprofloxacin (10 days BID 1gr) plus the placebo capsules representing Metronidazole and Amoxicillin. The other 12 patients named control group, received Metronidazole (7 days TID 750mg) plus Amoxicillin (7 days TID 1.5gr) and the placebo tablet representing Ciprofloxacin. Neither the patients nor the doctors knows the grouping sequences. Bacteria Culturing and measurement of Gingival Index (GI) and plaque Index (PI) were done at the baseline and repeated about 10 days after prescribing the medicines. T- test and chi-square test were used for Statistical analysis. Results: There was no difference between two groups in the A.a Positives sites, GI scores and PI scores at the baseline. Ciprofloxacin eliminates A.a from 91.7% of sites and Metronidazole plus Amoxicillin eliminate A.a from 81.3% of sites. There was no significant difference between the test and control groups. The mean PI score for test and control groups were 1.39±0.66 and 1.39±0.88 respectively at the baseline and these values were 1.27±0.6 and 1.43±0.81 after receiving the designed medicine. There were no differences inter and intra groups at any time (P>0.05). Conclusion: Ciprofloxacin is as effective as Metronidazole plus Amoxicillin in elimination of A.a from active sites in AgP patients. Their longitudinal effects on clinical parameters such as probing depth, clinical attachment level, bleeding on probing and microbial flora need to be investigated.
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Statement of Problem: The achievement of a good and durable dentin/composite resin bond is an important task in restorative dentistry. The application of acid conditioners and dentin bonding agents is an accepted method to enhance this bond strength. Pretreating of dentin surface by laser irradiation seems to be a supplemental way to obtain better results, since lased dentin is more roughened and has a widest surface area to interact with acid conditioner. Purpose: In this study, the effect of dentin surface pretreating by Nd-YAG laser on dentin/composite shear bond strength was examined. Moreover, the effect of Chinese ink as a surface energy absorber on this value was investigated. Methods and Materials: Thirty-nine freshly extracted human teeth without dentinal caries were collected and their occlusal dentins were exposed using a diamond disk. The collected samples were divided into three identical groups. The dentin surface of the first group was lased by an Nd-YAG pulsed laser (100 mJ, 20 Hz) through a 320 m fiber optic in a swiping movement. In the second group, 10% solution of Chinese ink was applied on the dentinal surface before lasing. The samples of the third group were not lased at all. The dentinal surface prepared by 35% phosphoric acid and Scotchbond MP primer and adhesive. Then, composite resin was cured on dentinal surface. After incubation, in water at 37°C for 24 hours, the samples were tested by Digital Tritest ELE machine. Results: The values of bond strength were 20.83±3.96 MPa, 17.83±3.63 MPa and 19.38±4.88 MPa for the lased, unlased and dye-enhanced groups, respectively. The results were not significant by ANOVA test (=0.05). Although in the Weiboul modulus, the lased group offered better bond strength. Conclusion: Further studies are required to determine whether chemical as well as physical alterations to the dentin surface are induced by laser etching, and whether these influence the performance of the range of dentin bonding systems used currently in clinical practice.
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Statement of Problem: Failure of endodontic treatment is determined on the basis of radiographic findings and clinical signs and/ or symptoms of the treated teeth. Purpose: The purpose of this study was to determine endodontic treatment failure in relation to various factors influencing it in teeth with periapical lesions (clinically and radiographically). Materials and Methods: Teeth which had periapical lesions before treatment were selected from a series of teeth treated by endodontics’ postgraduate students over 5-year period (1997-2001) in Faculty of Dentistry Tehran university of Medical Science. post operative follow up in 50 patients was possible .The patient’s ages ranged between 16 to 62 years old. 40 of patients were female and 10 were male. At the recall appointment, first the clinical information (pain, swelling, tenderness to palpation, percussion, …) were recorded in a questionnaire form, then two radiographies were obtained from each tooth. The radiographies were assessed separately by three to five endodontists. Strindberg's criteria were used to Judge the failure of endodontic treatment. The observation period ranged from 1 to 5 years. The Data were analyzed statistically by using chi-square, Fisher’s exact test and MC Nemar test. Results: Among different factors considered in this study, Fistula and sensation to percussion were reduced significantly (MC Nemar test, P=0.004). There were no significant difference between the extention of root canal filling, age and type of coronal restoration and endodontic failure which may be due to the small sample size of this study. Conclusion: The rate of endodontic failure was 16%, which means 84% success rate, which is similar to results obtained from previous studies. The high success rate of endodontic treatment in teeth with periapical lesion may be explained by the fact that obturation has a definitive effect on reducing inflammation in periradicular area.
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Statement of the Problem: The routine procedure for immobilization of free gingival graft (FGG) is suturing. Due to the successful application of tissue adhesives their employment has also become the subject of interest. Purpose: The aim of present clinical trial was to compare using Epiglu (E.g) versus silk thread suturing in FGG. Materials and Methods: This study was a split mouth clinical trial. The study group comprised of 12 patients with symmetrical loss of attached gingiva whom were referred to Faculty of Dentistry, Tehran University of Medical science. In test group, the gingival graft were placed on cellophane and after applying one drop of Eg then placed in the proper position. In control group silk suturing was used. Results: The degree of pain had no significant differences in two groups (P>0.05). The rate of bleeding was insignificant at the first day (P=0.5), but in the second (P=0.0425) and the third day (P=0.0313) less bleeding was observed in the test group. 10 days after the surgery, grafts in the test group had better healing (P=0.0425), while 3 month later no significant differences observed (P>0.05). Although the mean tissue shrinkage were 41% and 38% for control and test group respectively, Wilcoxon test showed no significant differences 30 days after surgery (P>0.05). The tissue shrinkage also was not significant 3 months after surgery. In addition, no displacement, infection or hypersensitivity were noted in either of two groups. Conclusion: In FGG, Epiglu is more effective than suturing.
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Statement of Problem: Sodium hypochlorite (NaOCl) have been widely used as an irrigant since it has been introduced to endodontics by walker in 1936, because of its bleaching, deodorizing and tissue dissolving properties. It should be used clinically in concentrations of 3% to 5%. Purpose: The aim of this study was to evaluate the effectiveness of the NaOCl to eliminate Enterococcus faecalis (E.f) from root canals in comparison with Normal saline. Materials and Methods: In an interventional study forty freshly extracted single canal human teeth were chosen. They were sectioned at the CEJ, instrumented and Sterilized. Then they were contaminated with E.f solution and incubated. These samples divided into two groups randomly. Root canals were irrigated and filled with 5.25% NaOCl for five minutes in group one, and with normal saline in group two. Then samples were obtained from canals with sterile paper points and cultured for four days. The appearance of turbidity in cultured solutions was the indication to of E.F presence. In order to confirm the specific presence of E.F, three complementary microbiologic tests were applied. Results: All cultures obtained from NaOCl group were negative and all of normal saline group were positive. Conclusion: these results indicate the ability of 5.25% NaOCl to eliminate E.F in prepared root canals with wide diameter.
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Statement of Problem: Physiologic pigmentation of oral mucosa is considered as a prevalent entity among black people and those having relatively dark skin. Gingival physiologic pigmentation may cause problems for some patients specially ladies as far as esthetics is concerned. To overcome the issue, the surgery might be suggested which can cause some problems due to its side effects. Cryotherapy which is recently suggested for removal of such pigmentations has more advantages like quickness, simplicity, lack of bleeding and scar compared to other methods. Purpose: In this research, the objective was to analyze the effects of cryotherapy on physiologic pigmentations of oral mucosa. Materials and Methods: In this study, ten patients who had oral mucousa physiologic pigmentation were selected and a questionnaire was filled out for every one of them. The location and extent of every lesion was determined and local anesthesia was obtained by supraperiostal infiltration. By applying nitrogen oxide (with the temperature of 89.5°C) and using a suitable probe of equal size of lesions, they were frozen for 20-30 seconds. Then patient were examined on the 2nd and 7th day, 2nd and 4th week post-operatively. Results: After four weeks all pigmented parts were cured and no recurrent lesion was observed in any of patients. Conclusion: Oral cavity is an ideal environment for cryotherapy and it can be used as an effective method for treating oral pigmentation and some other oral lesions.
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Statement of Problem: Odontogenic Keratocysts (OKC) make up 10-12% of all developmental cysts with dental origin. OKCs are classified into parakeratotic and orthokeratotic types, with completely different clinical features. In order to investigate biological behavior of OKCs, an immunohistochemical study was designed, using Ki-67 antigen as proliferation marker and P53 protein as tumor suppressor gene. Purposes: The aim of the present study was to investigate the expression of P53 and Ki-67 markers in two types of OKCs and to determine their relationship with the biological behaviour of OKC. Materials and Methods: A total of 20 OKCs (parakeratotic n=10, orthokeratotic n=10) were stained immunohistochemically for Ki-67 and P53 protein by Biotin – Streptavidine method. Then, slides were studied quantitatively through optical lense (magnification=X10) and the number of positively stained cells was counted/mm BM. Results: The average number of Positively stained cells for Ki-67 were 62.30±11.96 cells/mm BM in parakeratotic, and 29.90±4.90 cells/mmBM in orthokeratotic OKCs (P<0.05). Positive cells for Ki-67 were dominantly located in parabasal layer. Mean stained cells for P53 were 4.30± 2.21cells/mmBM in parakeratinized and 4.80±1.75 cells/mmBM in orthokeratotic types that was not statistically significant. (P<0.58) Parakeratotic OKCs mostly occur in the lower jaw (90%), whereas just 50% of orthokeratotic OKCs occur in mandible (P=0.05) Conclusion: Regarding other clinical features and the existence of daughter cysts, no significant statistical difference was found between two types of OKCs.
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Statement of Problem: Targis restorations provide good esthetic and clinical success; however, improving marginal accuracy requires further investigations. Purpose: The aim of this was to study evaluate the effect of relining on the marginal accuracy of ceromer crowns. Material and Methods: One ivorine maxillary central incisor was prepared for Targis crown. 10 acrylic models were duplicated from ivorine teeth. The specimens were randomly divided in to two groups. In the first group Targis crowns were made according to manufacturer's instructions. In the second group (relined group) after construction of Targis crown they were relined by Targis base. All of the specimens were luted with resin cement, embedded in epoxy resin and sectioned buccollingually and mesiodistally. Marginal and internal gap were assessed by image analysis system. Results: The mean marginal opening in labial and lingual margin of Targis crowns were 37.14±6.2 and 35.7±6.2 and in relined group it was 72.1±11 and 56±12µm respectively. Statistical analysis showed significant difference between two groups (P< 0.05). Conclusion: Considering limitations of this study, marginal opening and internal adaptation of the Targis crowns were in acceptable range for clinical application, however relining didn’t improve the fitness of crowns.
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Statement of Problem: Primary teeth discoloration can cause mentally and socially unpleasant effects in children. This can also be a sign of systemic disease. Despite the importance of this subject, a comprehensive study has not been performed yet. Purpose: The aim of this study was determining the frequency of different types of primary teeth discoloration. Materials and Methods: In this cross-sectional study 260 cases whom were referred to department of paediatric, faculty of dentistry, Tehran University of Medical Science, 1999-2001 were examined. All of these children were examined for any discoloration before starting any treatment then the type of discoloration was determined after polishing. Then the relationship between gender and these changes were evaluated by chi-square test. Results: In 59 cases (22.7%) abnormal color was detected. 10 patients (3.9%) had intrinsic stain and in 15 children (5.8%) extrinsic color was discovered. 34 children (13%) had both types. Conclusion: In this survey the correlation between tooth discoloration (and its types) and gender was not statistically significant.
