Journal of Dental Medicine

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Statement of Problem: Pain control is of high importance in dentistry. Prescribing sedatives such a Diazepam, as an anti-depressant and pain threshold elevator drug is able to influence the patient's reaction to pain and reduce it.
Purpose: The aim of the current study was to evaluate the effect of Diazepam in pain reduction following mandibular impacted third molar surgery.
Materials and Methods: In this study, which was conducted in the department of Oral and Maxillofacial surgery Faculty of Dentistry, Tehran University of Medical sciences. The patients were divided into two equal groups (n=30). For controls, antibiotics and analgesics were prescribed after surgery. However, except the aforementioned drugs, Diazepam (5mg), three times per day, was prescribed for the experimental group. The amount of mouth opening was also measured as an auxiliary sign after one week. The data were compared by
X2 test after one week.
Results: 60% of the experimental group and 13.8% of the control group felt a weak pain. Statistically significant differences were observed regarding pain feeling between two groups (P<0.001). Severe pain feeling was 34.5% and 10%, for control and experimental groups, respectively.

Conclusion: It is suggested that Diazepam is an effective pain reduction drug following third molar surgery.This drug has also a relative effect on temporary trismus resulting probably from muscle trauma or pain.

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Statement of Problem: Color matching and accurate shade selection are the challenging problems common to restorative dentistry. In ceramometal restorations, the type of substructure alloy affects the final color of bonded porcelain. Nickel- chromium alloy is the most commonly used one that its Iranian product, namely Minalux, is similar to Verabond2.
Purpose: The aim of this study was to assess and compare various color dimensions resulting from Minalux and Verabond2 alloys.
Materials and Methods: Nine disks, approximately 16 mm in diameter and 0.5 mm thickness, were cast from each alloy. Then, porcelain Vita VMK68 A2 was baked onto the entire test disks, following the manufacturer's instruction. Color samples, at the same time and under the same conditions, was measured by Data color spectrophotometer in CIE Lab System and Munsel system under four light sources (A, C, D65 and TL81). Then MATLAB TOOL BOX Statistic 5.2 was used to determine mean and bilateral variance analysis.

Results: It was indicated that the F value on hue, value and chroma was less than of the table value stated with 99% coefficient confidence, confirming Ho theory. In other words, there were not any significant differences between ceramometal disks made of Minalux and Verabond2 in the three dimensions of color.
Conclusion: Having desirable physical, mechanical and biological properties, Verabond2 can be replaced by Minalux alloy.

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 Statement of Problem:The choung osteotomy (Intraoral Vertico- Sagittal Ramus Osteotomy) has developed since 1992 in the treatment of mandibular prognathism. In IVSRO, osteotomy plane is theoretically parallel to the original sagittal plane and thereby attempting to decrease the incidence of condylar dispacement. This osteotomy designed additionally to decrease neurosensory disturbances.
Purpose: The aim of this study was to evaluate the incidence of neurosensory deficit and condylar displacement with IVSRO and Sagittal Split Ramus Osteotomy (SSRO).
Materials and Methods: In this study, mandibular set back surgery was accomplished upon 7 patients by choung osteotomy. In addition to choung osteotomy, in 2 patients Lefort 1 osteomy was performed for maxillary protrusion and for 2 other patients, chain surgery was performed. Variables such as the neurosensory disturbances of inferior alveolar nerve and condylar displacement following choung osteotomy were investigated. All the patients were followed up one year after osteotomy. OPG, Lateral Cephalogram and Submentovertex radiographies were take pre and postoperatively for all patients.
Results: No statistically significant differences were found in condylar displacement (P>0.5). However, Mc Nemar analysis showed significant difference of neurosensory deficit between IVSRO and SSRO (P=0.001).
Conclusion: It is suggested that choung osteotomy is a safe procedure for mandibular surgery.

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Statement of Problem: Composite reins have recently become popular for posterior teeth restorations. Gap formation and subsequent microleakage are of the complications resulting from such restorations. One of the techniques to overcome polymerization shrinkage of composite resins is sandwich technique (application of glass ionomer as a base beneath the composite resin). Since polymerization patterns in two types of composite resins (light cure and self cure) differ from each other, various effects on the bond strength between glass ionomer and dentin are expected.
Purpose: The aim of this in vitro study was to evaluate the effects of self- cure and light- cure composite resins in sandwich technique on the bond strength of light cure glass ionomer and dentin.
Materials and Methods: 40 extracted human premolars were selected and divided into four groups:Group 1: Light cure glass ionomer of 1mm thickness was placed on dentin.Group 2: 1mm thickness of light cure glass ionomer plus a mass of self cure composite resin of 2mm thickness were placed.Group 3: 1mm thickness of light cure glass ionomer plus light cure composite resin as two separate 1mm layer were placed.Group 4: 1mm thickness of light cure glass ionomer with 37% phosphoric acid etching followed by two separate layers of light cure composite resin of 1 mm thickness were placed.SEM was used to determine gap size ai Gl- dentin and Gi- composite interlaces. The findings were analyzed by ANOVA and t-student tests.

Results: Groups 1 and 2 showed no gap at Gl-dentm interface and also cracks were not observed in all these specimens. In group 3, there was gap between light cure GI and light cure composite resin and cracks were seen in GI, too. Group 4 showed gap at both interfaces and more cracks were seen in GI. Groups I and 2 showed the least gap formation and group 4 showed the most. Statistically significant difference was found between groups 3, 4 and group 1 (control), 2.
Conclusion: Base on this study, the application of self-cure composite resin on light cure GI showed no gap and crack formation on Gl-dentin and Gl-composite interfaces and GI itself. However, light cure composite resins and glass ionomer etching aggregated crack and gap formation.

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Statement of Problem: Tooth extraction is always considered as the final treatment option in dentistry.Considering the numerous advances in dentistry, nowadays the preservation of the permanent teeth until old age is common. However, in most economically poor countries or those without security service insurance,the high rate of extraction, particularly among restorable teeth, is regrettable.
Purpose: The aim of the present study was to determine the reasons for tooth extraction among patients referred to the faculty of Dentistry, Tehran University of Medical Sciences in 2002.
Materials and Methods: This descriptive and cross-sectional study was conducted on 320 patients. The information about patient's general knowledge, oral health status, tooth location and causes of extraction were collected and recorded in a questionnaire. The data were submitted to statistical Chi-Square test.
Results: No statistically significant difference was found between two genders in their mentioned causes for extraction. The most prevalent reasons were as follows: Caries (50%), Periodontal diseases (16.6%). Absence of an acceptable occlusion, prosthetic problems, patient's request, etc... make up the remaining 33.4% of the reasons.
Conclusion: According to this study, it is suggested to investigate extraction etiology at the society level and if similar results are obtained, necessary steps should be taken to prevent caries and periodontal problems as the major mentioned causes for tooth extraction.

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Statement of Problem: Nowadays economical issues on high gold alloys have changed the practice of metal-ceramic restorations toward base-metal alloys. Minalux is one of the base-metal alloys produced in Iran. Marginal fitness is of high importance to be evaluated in dental alloys.
Purpose: The aim of the present study was to compare the marginal adaptation of two base-metal alloys, Minalux (Mavadkaran Co. Iran) and VeraBond2 (Aibadent Co. USA ) during firing cycles of porcelain.

 Materials and Methods: In an experimental study 24 standard brass dies, with 135° chamfer finishing line were fabricated by Computer Numeric Controlled (CNC) milling machine. The samples were randomly divided in two groups, A and B, 12 in each. Following wax-up, the samples were equally cast with two mentioned alloys. In each group, there were 4 controlled samples, which proceeded to firing cycle without veneering porcelain. Scanning electron microscope (SEM) measurements of marginal gap from buccal and lingual aspects were performed after 4 stages of casting, degassing, porcelain application and glazing. The data were analyzed using Four-way ANOVA and multiple comparative test based on Tukey criteria.

 Results: The findings of this study revealed that there was no significant difference in the marginal gap of Minalux (31.10±7.8u.m) and VeraBond2 (30.27±6.96u.m) with confidence level at 0.95 (P=0.43). For both alloys the greatest gap was observed after degassing stage (P<0.05). Porcelain and porcelain veneering proximity caused significant changes in the marginal gap of Minalux castings (P<0.05), however, such changes did not occur in VeraBond2 (PO.05).
Conclusion: Based on the findings of this study, the marginal gaps of two base metal alloys, Minalux and VeraBond2, were proved to be identical and that of the Minalux alloy existed in the range of acceptable clinical application. It was also concluded that Minalux dental alloys could provide proper marginal adaptation.

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Statement of Problem: Root canal cleaning and shaping are important steps in endodontic therapy. In order to develop better techniques, new instruments are constantly designed and delivered to the market.
Purpose: The aim of the present study was to compare the effectiveness of one manual with three rotary root canal instrumentations techniques.
Materials and Methods: In this in-vitro study, 80 mesial roots of freshly extracted human mandibular molars were divided in to four groups equally and prepared by one of the following instrumentation methods profile NiTi rotary system, Protaper NiTi rotary system, Flex Master NiTi rotary system and hand NiTi K-file instrumentation. In each root one of the canals was instrumented and the other was used as control.After decalcification, cross sections at 3mm and 5mm of apical portion were prepared and examined for remaining debris, predentin and smooth walls under light microscope. The data were analyzed by Kxuskal-Wallis test.
Results: Significantly less debris was found at 3mm cross- section using protaper and Flex Master techniques (P<0.05). No significant differences were found at 5mm cross section. Also no significant differences were observed for remaining predentin at all regions. Significantly more smooth walls were found at both regions using protaper technique (P<0.05).
Conclusion: The protaper technique employed in this study resulted in cleaner root cana! walls than the
other techniques.

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Statement of Problem: One of the problems associated with the treatment of periodontal diseases is caused through the extension of disease toward furcation area. Several techniques in Conservative, Resective and Regenerative categories have been suggested for the treatment of furcation involvement.
Purpose: The aim of this study was to compare the results of the treatment of grade II furcation involvement in mandibular molars using an allograft material named 'Dynagraft' (a type of demineralized bone matrix) and the coronally positioned flap.

Materials and Methods: In this randomized controlled clinical trial study, twelve patients (9 females and 3 males), aged 25 to 40, suffering from bilaterally grade II furcation involvement of mandibular molars who referred to dental faculty Tehran University of medical Sciences, were investigated. The molars of one side were treated by Dynagraft whereas those of the opposite side underwent the CPF method. Measurements of the probing pocket depth (PPD), clinical attachment level (CAL), keratinized gingiva (KG) and horizontal probing depth (HPD) were recorded at baseline, 3 and 6 months after surgery. In order to investigate the bone radiographic changes, radiovisiography at the mentioned periods in addition to clinical investigation, were performed. For statistical analysis, Paired West was used.
Results: The mean PPD reduction three months and six months after the operation were 1.75 mm and 2.25mm, respectively in the Dynagraft (test) group whereas 1.26mm and 1.27mm in the CPF (control) group (P<0.005). The mean attachment gain three months and six months after the operation were 1.1 mm and 1.5mm respectively in the test group, and 0.2mm and 0.3mm in the control group (P<0.005). The mean KG reduction three months and six months after the operation were 0.5mm and 0.6mm respectively in the test group and those of the control group were 1.1mm and 1.1mm. The mean HPD reduction three months and six months after the operation were 1.55mm and 2mm respectively in the test group (P<0.005) and 0.55mm and 0.55mm in the control group (PO.01). Radiovisiography of the mentioned areas three months and six months after the operation confirmed the changes obtained from clinical measurements, showing appreciable reconstructive results (Bone filling) in the test group as compared with the control group. Moreover, root resorption was not observed.
Conclusion: Based on the results of this study, Dynagraft can be used as an appropriate material in the treatment of grade II furcation involvement in mandibular molars. However, for a through evaluation of such regenerative techniques in furcation involvement, further studies with larger population and long term follow up in addition to histologic studies are suggested.

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Statement of Problem: Chronic periodontitis is one of the most prevalent periodontal diseases in the world which may be treated through surgical or non-surgical approaches.
Purpose: The aim of this study was to compare the efficacy of Doxycycline and placebo following SRP in non-surgical treatment of chronic periodontitis.
Materials and Methods: This double blind interventional study was conducted on patients attended to the periodontology department of Tehran faculty of dentistry from 2002 to 2003. After SRP, 22 cases and 23 controls were received Doxycycline and placebo, 20 mg twice a day for 3 months, respectively. Bleeding on probing (BOP), pocket depth (PD)<6mm and PD>7mm, and also clinical attachment level (CAL)<6mm and CAL>7mm in cases and controls after 3 and 6 months were compared by student t-test.Results: BOP after 3 and 6 months in Doxycycline recipients following SRP were significantly lower than in placebo recipients (P^0.007 and P=0.045 respectively). PD<6mm, PD>7mm, CAL<6mm and CAL>7mm in 3 and 6 months after SRP in cases were much lower than controls.
Conclusion: This study showed that the administration of Doxycycline for 3 months after SRP resulted in improvement of clinical indices as compared with SRP alone. Therefore, Doxycycline administration is recommended for chronic periodontitis treatment after SRP.

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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.

Purpose: The aim of the present study was to evaluate the efficacy of periapical radiography on apical root resorption diagnosis. Materials and Methods: 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.

Results: 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%. Conclusion: 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.

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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.

Purpose: 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.

Materials and Methods: 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.

Results: 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.

Conclusion: 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.

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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.

Purpose: 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.

Results: 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).

Conclusion: In the present study, premature contacts at balancing side and secondary deepbite malocclusion were considered to be the most important etiologic factors of TMD.

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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.

Purpose: 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.

Materials and Methods: 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.

Results: 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.

Conclusion: 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.

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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.

Purpose: The goal of this study was to survey the effects of one-year occlusal adjustment on clinical success of non- carious cervical restorations.

Materials and Methods: 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.

Results: 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.

Conclusion: 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.

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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.

Purpose: The goal of this study was to compare benzydamine HCL 0.15% and Acetaminophen codeine as analgesics following periodontal surgery.

Materials and Methods: 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. Results: 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.

Conclusion: 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.

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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. Purpose: 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. Materials and Methods: The study was designed as a single blind randomised controlled trial protocol to compare the six accepted tooth brushing methods: 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).

Results: 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).

Conclusion: 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.

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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.

Purpose: The purpose of this study was to compare the interfacial fracture toughness of smooth and roughened ceramic surfaces bonded with a luting resin.

Materials and Methods: 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.

Results: 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. Conclusions: 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.

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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.

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Statement of Problem: There is a controversy about the relationship between pulpal and periodontal diseases. The interrelationship between pulp and periodontium could have an important effect on the treatment plan of the tooth.

Purpose: The aim of the present research is to evaluate root canal therapy effects on periodontal healing of teeth with chronic advanced periodontitis.

Materials and Methods: In this randomized controlled clinical trial 32 single rooted teeth which had necrotic pulp or irreversible pulpitis in 7 patients with chronic advanced periodontitis were selected based on specific criteria. Using a split mouth design, teeth were randomly put in two groups of test and control. In the test group root canal therapy ,scaling & root planing were done.In the control group, only scaling & root planing were performed. Clinical parameters including Pocket Depth (PD), Clinical Attachment Level (CAL), mobility, pattern of bone destruction and plaque index (PI) were evaluated in two groups at base line, 1 and 3 months after treatment. Appropriate tests such as paired Wilcoxon and Mann-Whitney were performed.

Results: Statistically significant reductions were found in the test group when comparing baseline and one-month post treatment values for Clinical Attachment level (CAL) but not after 3-months. In the control group the CAL reductions were not statistically significant between baseline and one month post-treatment, but a increase were observed between one month and three months after treatment. There was a statstically significant difference between the test and the control groups. Other parameters didn’t show any significant differences in each group and between two groups.

Conclusion: Since clinical attachment level was the most important parameter we found it can high lighted the role of pathogene with pulpal origin in progression of periodeontal disease and it is concluded that beside periodontal treatment in some advanced periodontal cases pulp therapy maybe an effective procedure for eleminating destructive pathogens of pulp and causing periodontal healing.

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Statement of Problem: In order to eliminate the esthetic problem of metal collar in porcelain fused to metal crowns various techniques, such as shoulder porcelain, have been suggested.

Purpose: The aim of this study was to investigate the effects of repeated porcelain firing cycles on the marginal integrity of shoulder in porcelain fused to metal crowns, made of two kinds of alloys: noble and base-metal.

Materials and Methods: In this experimental study, four groups of ten brazen models (Die) were used. Metal crowns of groups A&B were made of a noble alloy and those of C&D of a base-metal alloy. Groups A&C had the shoulder width of 1mm and groups B&D had the shoulder width of 1.5mm. After degassing and opaqing, shoulder porcelain was completed in the area of shoulder. At this stage, the average vertical gap of margin was measured by a reflective microscope (400). Data were analyzed using ANOVA and Duncan tests.

Results: No simoltaneouse interaction between the type of alloy and the shoulder width was found (P=0.709). The type of alloy had a significant effect on marginal integrity (P=0.021) attributing the best marginal integrity of shoulder porcelain to base-metal alloys. Shoulder width played also a significant role on marginal integrity (P=0.00) indicating that the reduction of shoulder width would increase the marginal integrity.

Conclusion: According to these findings, the best marginal integrity of shoulder porcelain is achieved through shoulder width of 1mm along with base-metal alloys.