مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال هفدهم شماره 2 (پیاپی 39، تابستان 1383)

Cervical third root defects, like perforations (due to resoption or iatrogeic), fractures or invasive decays make great difficulties for appropriate restoration making. In these circumstances crown lengthening is needed, especially for anterior teeth. Forced eruption also could be a beneficial treatment. By this therapy, cervical third root defects will be available to receive a good restoration. without gum and biologic width problems. In this article tried to introduce this method of therapy by reviewing litraure and with regard to personal research.

Statement of Problem: In a previous study it was reported that a durable resin-ceramic tensile bond could be obtained by an appropriate silane application without the need for HF acid etching the ceramic surface. Evaluation of the appropriate application of silane by other test methods seems to be necessary. The purpose of this study was to compare the interfacial fracture toughness of smooth and roughened ceramic surfaces bonded with a luting resin. Ceramic discs of 10 mm in diameter and 2 mm in thickness were prepared. Four different surface preparations (n=10) were carried out consisting of (1) ceramic surface polished to a 1µm finish, (2) gritblasted with 50µm alumina, (3) etched with 10% HF for 2 min, and (4) gritblasted and etched. The ceramic discs were then embedded in PMMA resin. For the adhesive area, the discs were masked with Teflon tapes. A circular hole with diameter of 3 mm and chevron-shaped with a 90° angle was punched into a piece of Teflon tape. The exposed ceramic surfaces were treated by an optimised silane treatment followed by an unfilled resin and then a luting resin cylinder of 4mm in diameter and 11 mm in length was built. Specimens were stored in two different storage conditions: (A): Distilled water at 37°C for 24 hours and (B): Distilled water at 37°C for 30 days. The interfacial fracture toughness (GIC) was measured at a cross-head speed of 1 mm/min. The mode of failure was examined under a stereo-zoom microscope and fracture surfaces were examined under Scanning Electron Microscope. The mean interfacial fracture toughness values were Group A: 1) 317. 1±114. 8, 2) 304. 5±109. 2, 3) 364. 5±169. 8, and 4) 379. 4±127. 8 J/m2±SD. Group B: 1) 255. 6±134. 4, 2) 648. 0±185. 1, 3) 629. 3±182. 6 and 4) 639. 9 ±489. 0 J/m2±SD. One way Analysis of Variance showed that there was no statistically significant difference in the mean interfacial fracture toughness for groups A1-A4 (P>0. 05). However, the mean interfacial fracture toughness for group B1 was significantly different from that for groups B2, B3 and B4 (P<0. 05). Independent-ٍٍٍSamples T-Test results showed that there was a significant increase in the GIC mean value for groups B2 and B3 after 30 days water storage (P<0. 05). The modes of failure were predominantly interfacial or cohesive within the resin. The fracture toughness test method used in this study would be appropriate for analysis of the adhesive zone of resin-ceramic systems. From the results, it can be concluded that micro-mechanical retention by gritblasting the ceramic surfaces could be sufficient with no need for HF acid etching the ceramic surfaces when an appropriate silane application procedure is used.

Statement of Problem: There are different tooth brushing methods for removing dental plaque from tooth surfaces. The effectiveness of these methods, and the time needed for instruction, learning and using seem to be different. Also, it is possible that the effectiveness of each method reduces with time, based on its difficulty level and the reduction of the patient s attention in following the given instructions. The aim of this research was to compare the effectiveness of six different accepted tooth brushing methods on total and specific teeth, as well as on special tooth surfaces. The research also compared the time needed for instruction, learning and using the methods. The study was designed as a single blind randomised controlled trial protocol to compare the six accepted tooth brushing Roll, Bass, Charters (C), Modified Stillman (MS), and Modified Bass in two ways (MB1-MB2). 15 volunteers were selected from the basic science level dental students at Tehran University of Medical Sciences. All the six methods were instructed to each volunteer, using a randomly selected sequence. Each participant should, therefore, pass six consequent courses, by the same sequences as follow: 1st Visit: After polishing the teeth, the participant was asked to abstain any kind of tooth cleaning. - 2nd visit (48-72 hours later): O Leary Plaque Index (PI) was recorded and then the randomised selected method was instructed. Then, the participant brushed his/her teeth and PI was registered again. The time needed for instruction and using the method was registered too. The participant was then asked to use this newly learned tooth brushing method twice a day for 7±1 days. - 3rd visit (7±1 days later): PI was recorded. The teeth were polished. The participant was asked to abstain any kind of tooth cleaning for 48-72 hours, as washout period of the previous method and preparation period for the next method (2nd visit of the next course). The final stage was comparing the results, in which the effectiveness of each method was evaluated based on the mean percentage of plaque reduction after the first usage, and also the mean percentage of the plaque remained after using the method for 7±1 days. The time needed for instruction, learning and using the methods were also compared. The statistical analysis was done using the SPSS software and variance analysis (randomised block design). Considering all the teeth and their total surfaces after 1st usage, the methods of C and MB1 were statistically more effective than the other methods. But the difference between these two methods was not significant. Also after 7±1 days, the differences between all methods were not statistically significant. On the posterior teeth, after 1st usage and also after 7±1 days, the method of C was significantly more effective than the others, with the exception of MB1 for which their differences were not significant. Also MB1 was significantly more effective than the methods of Bass and Roll, but only after the 1st usage. On the anterior teeth, after 1st usage, method of C was statistically more effective than the methods of Bass, MB2 and MS. Also MB1 was significantly more effective than MB2 and MS. But after 7±1 days, the differences proved insignificant. Considering the specific surfaces of the teeth on the proximal surfaces, after the 1st usage of the methods, the methods of C and MB1was significantly more effective than the others, except each other, which their difference was not significant. But after 7±1days the method of C was statistically more effective only than the methods of Bass, MB2 and MS, and the method of MB1was significantly more effective than MB2. On the buccal and lingual surfaces the differences were not statistically significant at both stage of evaluation. When statistically considering the time needed for instruction, learning and usage, the method of C needed more time than Bass and Roll methods. In the same way, MB1 needed more time than Roll method. The most time needed was related to MB2 which was more than the time needed for the methods of Bass, Roll and MS (P<0.001 and α=0.05). The tooth brushing methods of Charters’ and a kind of Modified Bass method (in which Bass and Roll methods are used separately and consequently) were evaluated as the most effective methods.

Statement of Problem: Systemic analgesics are frequently prescribed for pain reduction following periodontal surgery. This type of treatment, however, brings about some disadvantages due to its late effect and inherent side effects. Benzydamine hydrochloride mouth wash is a non steroidal anti-inflammatory drug with local anaesthetic properties. Side effects of benzydamine are minor such as tissue numbness, burning and stinging. It brings relief to pain and inflammation rapidly. The goal of this study was to compare benzydamine HCL 0.15% and Acetaminophen codeine as analgesics following periodontal surgery. This clinical study was performed on 18 patients referred to periodontics Department, Faculty of Dentistry, Tehran University of Medical Sciences. All patients were affected with chronic mild or moderate periodontitis and required surgery at least at two oral sites with similar lesions. Each patient received benzdamine HCL after first surgery and Acetaminophen codein following second operation. Pain reduction was evaluated by Visual Analog Scale (VAS). Data were analyzed with Wilcoxon-Signed and Mann-Whitney non-parametric tests. Analgesic effect of Acetaminophene codeine was significantly more than that of benzydamine HCL following Reriodontal surgery (P=0.008). No significant difference was found between analgesic effects of Acetaminophene codeine and benzydamine HCL in patients with chronic mild periodontitis (P=0.9), and in cases that osteoplasty (P=0-31) or no osseous surgery (P=0.18) were performed. In cases with mild post-operative pain following periodontal surgery, Benzydamine HCL and be prescribed as an analgesic. However, in other cases this mouth wash should be prescribed along with Acetaminophene codein to reduce systemic drugs consumption.

Statement of Problem: Parafunctional habits are the most important factor in the creation of non-carious cervical lesions and correcting of these habits may affect cervical lesions. The goal of this study was to survey the effects of one-year occlusal adjustment on clinical success of non- carious cervical restorations. In this clinical study, sixty tooth-colored cervical restorations on canines and premolars in patients with parafunctional habits (bruxism and clenching) were studied. The teeth, according to the type of restorative material, were randomly divided into two groups: One group with a composite resin (Tetric Flow Group A: n=30) and the other group with a compomer (Compoglass Flow Group B: n=30). After restoration, each group was divided into two subgroups: (A1, B1) with occlusal adjustment (case group), (A2, B2) without occlusal adjustment (control group). The evaluation was perfumed single blind at 6 and 12 months after restorative operations according to Us Public Health Service (USPHS) classification. Assessment criteria included: marginal integrity, marginal discoloration, recurrent caries, postoperative sensitivity and loss of filling. Statistical analysis was completed using Fisher’s exact test. In 12 month period between two groups of compoglass Flow restorations, group B1 showed superior results than group B2, however, no significant difference was found between both groups of tetric flow restorations (A1 and A2). There was also no difference in clinical conditions between A2 and B2 groups. Considering the results of this study, it can be concluded that occlusal adjustment puts a considerable effect on clinical success of compoglass non- carious cervical restorations. However, it should be mentioned that such and effect was not found among Tetric flow restoration.

Statement of Problem: Pulpotomoy is considered as one of the most common treatments among primary teeth. Therefore, search for an appropriate and safe material seems necessary. Studies have proved ferosulfate as a therapeutic material in pulpotomy. The goal of the present study was to compare clinical and radiographic changes of pulpotomy using ferosulfate and formocresol in primary molars among 3-8 year old children. In this clinical trial study, fifteen 3-8 years old children, referred to the pedodontics department, faculty of Dentistry, Tehran University of Medical Sciences were selected. All subjects did not show any systemic disease, with at least two clinically and radiographically accepted posterior teeth for pulpotomy technique. Totally, forty- three teeth were studied. For each patient both materials were used. Following treatment, patients were investigated, clinically and radiographically in 3, 6, 9 and 12 month follow-ups. During follow-up periods, teeth with failures were not excluded and investigated. For data analysis, Chi-square and Fisher’s-exact tests were used and treatment success was evaluated, based on clinical as well as radiographic findings. In all follow-up periods (3, 6, 9 and 12 months after treatment), pulpotomies with formocresol showed more success rate (73.7%) comparing to those with ferosulfate (70.8%), although the difference was not statistically significant (P>0.05). Statistical tests revealed no significant difference between two different treatment techniques regarding pain, external and internal resorption, calcified metamorphosis, abcess, apical root resorption, apical and interradicular radiolucency. Although ferosulfate, due to its less toxicity, may be considered as a proper substitute for formocresol in primary molars pulpotomies, more studies with longer-term follow up and larger sample size are required to determine its long-term effects.

Statement of Problem: In recent years, the prevalence of temporomandibular disorders among children and adolescents has increased, however, no study on the correlation between occlusal relations and temporomandibular disorders, in Mashhad adolescents, has been conducted yet. The aim of this study was to survey the relationship between occlusal indices and temporomandibular disorders (TMD) among Mashhad adolescents, with the age range of 11-14 years old. Methods and Material: In this descriptive cross-sectional study, 1066 students (533 males and 533 females), age ranging from 11-14 years old (12.620.96 years), from seven Mashhad educational regions, were selected. Temporomandibular joints were thoroughly examined for all subjects. All occlusal indices including dentition system, angles classification, types of malooclusion such as cross-bite, deep-bite as well as types of lateral occlusion, premature contacts in lateral and protrusive movements were investigated. Data were analyzed statistically using, Chi-Square and logestic regression tests. The prevalence of TMD was 23.5%. There was no significant relation between TMD and type of dentition, angles classification and type of occlusion in lateral movements, however, statistically significant relation was found between TMD and deep over bite (P<0.05). Premature contacts in lateral movements at balancing side were proved to be significant etiologic factors of TMD (P=0.003). In the present study, premature contacts at balancing side and secondary deepbite malocclusion were considered to be the most important etiologic factors of TMD.

Statement of Problem: Considering that the role of collagen fibers in dentin adhesion has not been thoroughly established yet, the removal of exposed collagen fibers with a deproteinization agent such as sodium hypochlorite following etching may facilitate access of adhesive resins to a substrate that is more penetrable and less sensitive to water content which in turn would lead to a more durable bonding system. Furthermore, due to sodium hypochlorite clinical application as a cleanser or canal irrigator, its effects on the surface before etching may influence adhesive bonding strength. The goal of this study was to evaluate the effects of a two-minute 5.25% NaOCL application on composite restorations microleakage, using two different adhesive systems. In this interventional experimental study, on seventy-two extracted boving incisors class V cavities were prepared on dentinal surfaces. The specimens were then randomly divided into six equal groups: A1) Acid etch (AE) dentin bonding Scontchbond Multipurpose Plus (SBMBP), A2) AE/ dentin bonding One Step (OS), B1) NaOCL/ AE/SBMPp, B2) NaOCL/AE/OS, C1) AE/NaOCL/SBMPp, C2) AE/NaOCL/OS. After bonding procedures according to the manufacturer’s instructions, cavities were restored using Z100 composite. Then, the specimens were thermocycled for 500 times in water baths of 5 and 55C. After thermocycling, the specimens were immersed in a 0.2% solution of basic fuchsin for 24 hours. A buccolingual section at the center of each restoration was obtained and examined with a stereomicroscope to evaluate color penetration into cavities. The data were subjected to two-way variance analysis. The microleakage of group B was significantly less than those of A and C (P<0.001). No significant difference was found between groups A and C (P=0.73). There were also no significant differences within groups A, B and C (P=0.852). No interaction was observered between dentin bondings and surface treatment (P=0.946). The findings of this study revealed that NaOCL application after etching, for hybrid layer removal, did not make any difference on microleakage as compared with conventional bonding systems. However, its application before etching improved the seal of restoration. Additionally, there was not any significant difference between two different dentin bondings.

Statement of Problem: Gingival overgrowth is a side effect commonly induced by Cyclosporin treatment. The effects of Azithromycin, a macrolidic antibiotic, has been focused on gingival enlargement treatment induced by cyclosporine in numerous articles. The goal of the present study was to survey the effects of systemic Azithromycin in the treatment of gingival overgrowth induced by cyclosporine among renal transplant patients. In this clinical trial study, 18 renal transplant patients (6 females and 12 males) with gingival overgrowth were studied. Samples were randomly divided into two groups: case group were treated by systemic Azithromycin and controls were treated by systemic placebo. Periodontal parameters including bleeding on probing (BOP), clinical crown length (CL), periodontal pocket depth (PPD), gingival overgrowth (GOI) and stent-IDP (vertical distant between a stent or plate with teeth occlusal planes at least from three of the most anterior contact points to mesial papillae) before treatment, two and six weeks after treatment were measured. To analyze the data, Wilcoxon and Mann-Whitney tests were used. Most of the measured indices, among case and control groups, were significantly improved, after two weeks (P<0.05). No statistically significant differences were found between two groups except for BOP index (P<0.05). In other words, more BOP improvement was observed in the case group after six weeks comparing to the control group. Considering the findings of this study, one can assume that the reported effects of Azithromycine on gingival overgrowth, induced by cyclosporine is somehow exaggerated and the effects attributed this medicine is probably inflammation reduction.

Statement of Problem: One of the dental lesions which is mainly diagnosed by periapical radiography is apical root resorption Diagnosis of the presence and extension of this lesion can put some effects on its treatment plan and prognosis. The aim of the present study was to evaluate the efficacy of periapical radiography on apical root resorption diagnosis. In this experimental study, sixty extracted teeth were examined radiographic and histological regarding the presence and extension of apical root resorption. It should be noted that periapical radiographs were taken before extraction of all mentioned teeth. The results were analyzed by Fisher’s exact test. The results of this study showed significant differences between radiological and histological examinations (P=0.0003). Significant correlation between these two observations was seen only in 53.33% of cases comprising 23% of teeth with root resouption. Non-correlation was found in 46% of samples. Moreover, there was no significant difference in the prevalence of apical root resorption between maxillary and mandibular teeth (P=0.233). Sensitivity of periapical radiographs in apical root resorption diagnosis was determined 57.3%. According to the findings of the present study, it seems that periapical radiography technique does not possess desirable efficacy in diagnosis of apical root resorption and its limitation should be considered by clinicians.

Statement of Problem: Different temperature and moisture around Iran and wide usage of stone type IV in dental laboratories in our country were the reasons for us for doing this study. In this survey the effect of temperature, moisture and time on dimensional change of dental stone type IV (Velmix) were investigated. In this experimental study cube shape Metal models (10×10×10mm) was made for Taking impression. We used special tray, which has ten holes (15×20×25mm) and made impression with condensational silicone in two-step procedure, and poured it with stone type IV. stone cubes were divided to different groups. 3 groups holed in fix moisture and variable tempraure and 5 groups in fix temperature and variable moisture. After 2 hours, 24 hours and one-week dimension of stone cubes were measured. Then analysis was done with ANOVA and dauncan. The following conclusions were achieved: 1-Time has no effect on dimensional changes. 2-Tempreture and moisture has some effect on dimensional changes in stone IV. Increasing of temperature result in stone contraction and increasing in moisture result in stone expansion. The best temperature for least dimensional change is 20C and the best moisture for a least dimensional change is 30 %.

Benign mesenchymoma is a soft tissue neoplasm that contains 2 or more mature mesenchymal tissues in addition to fibrous tissue. A rare case of gingival benign mesenchymoma in a 53- year- old man is presented and the clinicopathologic characteristics of this uncommon tumor in the head and neck region is reviewed and discussed.