Journal of Dental Medicine

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Electromyographic (EMG) investigations about the activities of the muscles have been the focus of attention for many years. In the field of orthodontics, investigators, among other things, tried to evaluate correlation between EMG activity, occlusal relationships and craniofacial morphology to analyze the effect of muscular activity, as an etiological factor in malocclusion. The purpose of the present investigation is to analyze the effect of EMG activity of temporal and masseter muscles quantitatively in skeletal class III malocclusion. 26 patients (9 to If years old), with class III malocclusion were selected and their EMG activity of temporal and masseter muscles in rest position, centric occlusion, clenching, mastication and swallowing were compared with 20 normal children at the same age range. Then the statistical correlation between 13 cephalometric parameters and EMG activities were analyzed and then the regression analysis was performed and the results were as follows:
1- The mean amplitude of masseter and temporal muscles activity in rest position, centric occlusion, mastication, and clenching in class III samples were greater than normal group (PO.05).
2- The mean duration of masseter and temporal muscles activity in rest position and centric occlusion in class III samples were more than normal group (PO.05).
3- According to regression analysis, a linear correlation was observed between ANB angle and temporal muscle activity in rest and centric occlusion that was not observed in other cases.
The findings of this study showed that difference in temporal muscle activity in class III malocclusion, in comparison with the normal group, is correlated with skeletal morphology of the face, but according to other investigations it is not ture for the masseter muscle.

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During pregnancy, different froms of periodontal disease such as pregnancy gingivitis, pregnancy tumors, pregnancy stomatitis, may be encountered. But the most considerable point is the pregnant women's infection with periodontal disease and its effect on delivery and weight of newborn infants. Based on the latest researches and statistics, it is concluded that periodontal disease is an important risk factor, leading to preterm or premature delivery. On the other hand, poor hygiene, should be considered as another danger, resulting in premature delivery. Besides, the presence of a collection of oral fosobacteria in ammoniutic fluid in mothers with premature delivery, increases the probability of an oral- haematogenous connection. Moreover, prostaglandin E2, in cervicular fluid, has been considered as an index for periodontal disease activity and loss of weight at the time of birth. These findings suggest that effective steps, to prevent preterm delivery, can be taken, if women, genycologists and dentists have enough knowledge. This article focuses on the special supervision that is required to prevent the effects of hormonal changes on periodontal tissues and conversely to reduce systemic disorders resulting from periodontal disease, in pregnant woman.

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Dept. of Oral and Maxillofacial Surgery, Ghazvin University of Medical Sciences A lot of studies have discussed the reduction of mandibular movements range after orthognatic surgeries. The present study focuses on the conventional orthognatic surgery methods to determine the method with the least effects on mandibular movements. Sixty patients were investigated in a prospective study. They were divided, based on the surgical method, into three groups. In the first group (20 patients) sagital osteotomy, in the second group extra oral vertical osteotomy for mandibular retrusion, and in the third group simultanouse Bimax osteotomies of the upper and lower jaws, were performed. The surgical method applied for maxilla was Lefort 1 osteotmy to protrude the upper jaw and of the lower jaw was extraoral vertical osteotmy. The range of mouth opening, in centrals region, right and left lateral movements and protrusive movements, before and three months after surgery, were measured. Sagital osteotomy method (the first group) showed the most changes and reduction in movements, while the least changes were observed in extraoral vertical method (the second group).

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Due to the differences in the composite and morphology of dentin in primary and permanent teeth, it is necessary to make improvements in bonding techniques to promote the strength of composite resins bonded to the dentinal surface, in primary teeth. The use of lower radiation, to make structural and chemical changes in dentinal surfaces has been investigated. This research was conducted to evaluate the shear strength of the composite bonded to primary teeth dentin after Nd: YAG laser radiation and acid etching for conditioning. Peripheral dentin of the buccal and lingua! surfaces of 60 extracted posterior primary teeth were exposed and polished with 600 grit with Sic paper. The teeth were divided randomly in 3 groups of 20 teeth. In group 1 etching gel, primer and adhesive of scotch bond multipurpose system (SMP), in group 2 laser at 1.6 w and 80 mj/pulse, and in group 3 laser at 2 s and 700 mj/pulse were used. Moreover, in groups 2 and 3, after laser radiation, acid etching, primer and adhesive of SMP system were applied. After necessary laboratory tests, the mean shear bond strength in MPa were 20.99±5.3 (group 1), 23.82±6.31 (group 2) and 26.58±5.59 (group 3). ANOVA, scheffe, tukey statistical tests showed that the bond strengths of group 3 were statistically higher than group 1. The frequency of dentin cohesive failures were significantly higher in groups 2 and 3, compared to group 1 that indicates a higher bond strength in these groups. Scanning electron mirographs of laser radiated surfaces, show a porous and rough surface morphology that enhances the mechanical bond of the composite.

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Conventional cephalometric analysis, based on intracranial reference line SN and Frankfurt plan, sometimes leads to incorrect diagnostic findings and unpleasant theraputic results, especially in orthosurgery patients, mainly due to the instability of the mentioned references. Natural head position (NHP) is the standardized orientation of the head that its record in lateral cephalometric radiographs, provides us with extracranial references. The aim of this study is to evaluate the necessity for providing a lateral cephalogram in NHP for diagnosis and treatment of severe malocclusion (orthosurgery) in comparison with mild to moderate malocclusions. For this reason, 28 orthodontic and 26 orthosurgery patient's cephalograms, in natural head position, were selected. Diagnosis and treatment planning were based on clinical evaluation and cephalometric analyses especially Harvold and Tweed ones. Each group, based on their growth pattern, was divided vertically and horizontally. The angles between SN and TH planes with TH (True vertical Sine) were measured. Then, the correlation between the angles in two groups and also in relation to the severity of malocclusion, were analyzed in vertical and horizontal directions. The results of two groups were compared by the independent t-test. The findings of this study showed that:1- The SN line was found to be more inclined than FH line and in orthodonthic patients, FH plan is a more reliable reference than SN.2- In orthosurgery patients, the SN-TH and FH-TH angles were strongly different statistically.3- Variation in SN-TH angle, in patients with vertical growth pattern, was high in both groups of patients.These conclusions prove the necessity of a lateral cephalogram in NHP for all orthosurgery patients and those orthodontic patients with vertical growth pattern.

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Muscular pain is one of the most common causes for facial pain. Myofacial pain dysfunction syndrome (MPDS) is one of the most important disorders of facial area that affected patients suffer from pain, tenderness of one or more masticatory muscles and limitation of movements. Lack of specific and effective therapeutic method, makes it necessary to find a treatment to decrease pain. Considering the analgesic and anti- inflammatory effects of low-level laser, some investigators have recommended it for MPDS patient's treatment. In this study, the effects of low level laser (Ga-Al-As) on MPDS patients referred to dental faculty of Tehran University of Medical Sciences, were investigated. Twenty- two MPDS patents, with mean age 33.32 years, were treated for 4 weeks (12 visits). Clinical examinations were performed in 6 stages. The results of this study showed that variables such as pain severity, cheek pain, pain frequency and tenderness of masseter, temporal, internal and external pterygoid muscles, had a statistically significant improvement at the end of treatment with low level laser (GA-A1-AS) which lasted for three months, (follow- up period). Results of this study showed that, low-level laser therapy has a sedative effect on the pain and tenderness of masticatory muscles in MPDS. Patients and having an accurate and regular program to complete treatment period, has an important role in MPDS improvement.

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Ultrasonic scaling of class V composite or glass Ionomer restorations may cause destructive effects. The purpose of this study is to investigate the effects of ultrasonic scaling on the marginal leakage of composite and Glass Ionomer restorations. An in-vitro study was performed on thirty- two upper and lower premolar teeth, free of any kind of caries, cracks or facets. Class V cavities, with the depth of 1.5 mm and the height and width of 2 mm, were prepared on the buccal and lingual surfaces. Occlusal margin and cervical margin were placed entirely in enamel and cementurn, receptively. Thirty-two cavities were restored with composite resin (Z100) (3M Co.), while the other thirty- two cavities were restored with Glass Ionomer cement (Vitremer) (3M Co.) and were bonded with Scotch Bond Multipurpose Plus (SBMP) (3M Co.). Half of each group were thermocycled, then half of each thermocyled and non-thermocycled groups were selected randomly for ultrasonic scaling test. After scaling, all teeth surfaces were coated with two layers of nail varnish up to 1mm of restoration. Samples were immersed in 0.5% fushin solution for 24 hours and were vertically sectioned by a diamond disk. Regarding dye penetration and microleakage, samples were examined by a stereobinoclar microscope. The results were analyzed by Mann-Whitney and Kruskal Wallis (a=0.05). They indicated that degree of microleakage in the composite/ enamel, with thermocycling and ultrasonic scaling were less than Glass Ionomer samples. Although in cervical margin, at the beginning, composite leakage was significantly less than Glass Ionomer cement, but thermocycling and ultrasonic scaling and their combination increased it and had a meaningful difference with Glass Ionomer.

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Microkeakage is one of the most important factors in restoration longevity. Microleakage can lead to recurrent caries, marginal fracture, marginal discoloration and tooth sensitivity. Several methods have been used for in-vitro measurement of microleakage. The present study is a review of the articles,from 1967 to 1999, which have been present in Medline.

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Esthetic is a natural necessity among all human beings, and the reconstruction of the natural features of prosthesis is considered an important aspect in dentistry. Reconstruction of the natural features in removable prosthesis by characterization of denture base is one of the most important factors. In this regard esthetic, in removable prostheses, is achieved through different techniques such as: tooth selection and arrangement, designing the denture base and acrylic base color. The final goal for ail these effects is to achieve a natural appearance for denture. However, other factors such as treatment limitations, different personal needs and general health principles, should be taken into consideration. This article not only reviews the natural appearance of oral mucosa that is replaced by the denture base, but also discusses about the materials used in tinting acrylic denture base and their application techniques.

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Retention, resistance and marginal integrity mostly depend on tooth preparation. An appropriate convergence angle fulfil this purpose, to high extent. In this study, a new method was used to measure the convergence angle of the teeth prepared for single crowns in Genera! practitioners" offices in Tehran. In order to do this. 325 dyes, prepared by General dentists in Tehran, were collected from 10 laboratories. All dyes wore trimmed at the area below the finishing line and then were scanned (Genius Color page- FIR 6) buccoiingualiy and mesiodistaily. Convergence angle of dyes were also measured with Adobe Photoshop (5.0) software. Data were analyzed by variance analysis test and 1- student bv the help of SPSS software. Results showed that the average convergence angle ranged from 16.18+8.34 to 35.1 8~10.38 which belonged to maxillary canine and mandibular molars, respectively, and the measured convergence angle is more than the ideal value of 10-16 degrees. Dyes of the madibular molars were ma"illar" convergent. These conclusions are helpful for professors, dentistry students and dentists, and arc an indicative of the practice quality of General practitioners in Tehran. Due to the fact that a convergence angle, more than the allowed limitation, endangers retention, resistance and marginal integrity of the restoration, paying attention to the principles of tooth preparation and proper application of instruments and dental cements, can progress fwed restorations quality.

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Recently. Minalux alloy, a base metal free from Be, has been presented on the market while no special soldering has been recommended for it. On the other hand, based on the manufacturer's claim, this alloy is similar to Verabond2. The aim of this study was to investigate the tensile strength of Minalux and Verabond2, soldered by Verasolder. Twelve standard dambble shape samples, with the length of 18 mm and the diameter of 3mm, were prepared from each alloy. Six samples of each alloy were divided into two pieces with carboradom disk. Soldering gap distance was 0.3mm, measured by a special jig and they were soldered by Verasolder alloy. Six other samples, of both Iranian and foreign unsoldered alloys were considered as control group. Then samples were examined under tensile force and their tensile strength was recorded. Two- way variance analysis showed that the tensile strength of Minalux alloy and Verabond2 were not statistically significant (Verasoler 686, Minalux 723), but after soldering, such difference became significant (Minalux 308, Verabond2 432). Verabond2 showed higher tensile strength after soldering.

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Waxes have a lot of applications in dentistry. Such materials are of thermoplastic type that undergoes deformation in different temperatures. Two important properties of base plate waxes are flow and their coefficient of linear thermal expansion. Recently, different institutions, inside the country, produce dentistry waxes, while they have not been standardized. Consequently, consumers' dissatisfaction are observed. In this research, the two above- mentioned factors were compared between three kinds of Iranian waxes with Cavex that is foreign production, based on test number 24 of ADA. To measure the flow rate in the temperatures of 23, 37 and 45°c, Wilcoxon statistical analysis was used. The results showed that in 23°c, the flow rate of Cavex and Azardent waxes met ADA standards however, it was not true for two others types. In 37°c, the flow of none of the waxes was standardized and in 45°c their flow was acceptable, moreover, thermal expansion coefficient, for Cavex and Azardent types, was based on ADA standard.

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Dentine bonding systems are usually unfilled, and so their shrinkage may be significant. High shrinkage may cause internal stress at the interface between resin-composite restoration and the dentine substrate. Failure of the adhesive interface may be observed due to the interna! stress. The aims of this study were:A) To obtain a suitable method for measuring the kinetics of polymerisation shrinkage in unfilled resm at different thicknesses, particularly for thin films.B) Consideraing the effect of thickness on shrinkage.Scotchbond Multipurpose (3M) adhesive bond resin was used. To overcome the particular challenges presented by thin films, a filled-ring measurement procedure was used. Also, a non-contact laser analogue displacement sensor system was developed and applied to measure polymerisation shrinkage. Regression analysis was performed on a complete data set. Non-linear regression analysis established a logarithmic relationship between polymerisation shrinkage and layer thickness. The method applied in this study was found to be sensitive and accurate procedure for determining photo-polymerisation shrinkage of thin films. Polymerisation shrinkage increased with logarithmic of the adhesive thickness.

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This review was focused on investigations in the relationship between human leukocyte antigens and periodontal disease. Several studies have looked for relationship between HLA phenotypes and early onset periodontitis (EOP). There have also been reports on both positive and negative relationship between specific HLA antigens and periodontal disease. Positive relationship has been reported among HLA-A1, A9, A24, A28, A33, B15, B22, B35, B44, C4, DR2, DR4, DR7, DR53, DRB1, DQ3 and DQB1 antigens and different forms of EOP. Several studies have reported negative relationship with HLA-A2, A5, A10, A28, A68, B5, DR2 and DR6. Two antigens that appear to be more related to EOP are HLA-A9 and DR4. Evidence suggests that genes in this area are not genes with major effect for early-onset periodontal diseases. It is possible that genes in the MHC region of chromosome 6 may function as modifying genes that affect clinical expression of periodontal disease. However, additional documents are needed to evaluate the relationship of HLA antigens with periodontal disease. These documents should have adequate controls, which account for racial differences in HLA type and well-defined patient groups whose state of disease is described

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Diagnosis and treatment of patients with periodontitis as a manifestation of systemic diseases is of especial concern to the periodontist, especially those associated with genetic disorders, which have poor prognosis. With aggressive progression of periodontal bone and attachment loss, a patient could be a partial or total edentulous early in life.The aim of this article was to report a case of Papillon-Lefevre syndrome (PLS) with generalizedprepubertal periodontitis (GPPP). A ten-year old boy for whom active periodontal treatment and subsequent maintenance recalls was performed for five years since the diagnosis of PLS. Treatment procedures included: precise mechanical instrumentation at several visits, periodontal surgery, adjunctive serial systemic antibiotic therapy, professional irrigation of pockets with 0/2% chlorhexidine solution and periodic maintenance recall visits. In spite of all of these, progressive course of the disease continued until the patient was fifteen and edentulous. Unfortunately association of GPPP with systemic unmanageable condition or diseases has caused refractory periodontitis, which yet has no proven and reliable treatment protocol. Besides, this article has discussed more successful treatment modalities for PLS with GPPP and the genetic aspects of host susceptibility, which is a complicated and challenging field.

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There are many researches evaluation different methods for covering the root surface. In the most of these studies, type I and II of Miller treatment had been searched. The purpose of this study was a comparison between connective tissue graft (CTG) and guided tissue regeneration (GTR) with a collagen membrane in the treatment of gingival recession defects (Miller class III). Six patients, each contributing a pair of Miller class III buccal gingival recessions, were treated. The clinical measurements were obtained at baseline and 1,2,4,6,12,18 months after surgery. Statistical analysis were performed using paired t-test between periods (baseline versus 6 months and baseline versus 18 months) within each treatment group and also between treatment groups before treatment and 6, 12 and 18 months after the treatment. The treatments were compared by a triple analysis of variance along the time (treatment, patient, time). Both CTG and GTR with a bioabsorbable membrane demonstrated significant clinical and esthetic improvement for gingival recession coverage. The CTG and GTR procedures had mean root coverage of 55% and 47.5% respectively, in the end of study. The CTG group was statistically better than GTR for recession depth, recession width and keratinized tissue width. Also, passing the time (18 months) as a distinct factor of treatment procedures was effective in increasing of clinical attachment level and keratinized tissue width.

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One of the most important characteristics of denture base is thermal conductivity. This property has a major role in secretions of salivary glands and their enzymes, taste of the food and gustatory response. Polymethyl methacrylate used in prosthodontics is relatively an insulator. Different materials such as metal fillers and ceramics have been used to solve this problem. The aim of this study was the evaluation of AI2O3 effect on thermal conductivity of heat-cured acrylic resin. Acrylic resin was mixed with AI2O3 in two different weight rates (15 and 20 % of weight). So, group 1 and 2 were divided on this basis. Samples with pure acrylic resin were considered as control group. 18 cylindrical patterns were made in 9x9 mm dimensions and thermocouple wires embedded in each sample to act as conductor. The specimens were put in water with 70±1°C thermal range for 10 minutes. Then, thermal conductivity was measured. The results were analyzed with variance analysis and Dunken test. There was significant difference between thermal conductivity of all groups in all period times. It the first seconds, thermal conductivity in groups 1 and 2 were more than control group. Therefore, for developing of thermal conductivity of acrylic resin, A1203 can be used. Certainly, other characteristic of new resin should be evaluated.

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Nowadays, different materials have been used for regeneration of interosseous defects and Neo-Os is one of them. The objective of this study was to evaluate histologically the influence of Neo-Os® particles on bone regeneration using rabbit caivarias defects with and without protection of Gore-Tex® barrier membrane. A cutaneous- periosteal incision and flap was made on the forehead of 32 rabbits exposing the top o"" the skull. A standardized trans-osseous skull defect (8 mm diameter) was made in each of the parietal bone with rotating round bur. In half of the rabbits, one defect was filled with the Neo-Os® particles without any type of the barrier membrane. The other defect was left empty. In the other half of the rabbits, one defect was filled with Neo-Os® and two flat expanded polytetrafiuoroethyiene (Gore-tex®) membranes. For the other defect, only the Gore-tex membrane protected the defect. After 8 and 16 weeks, the specimens were processed using standard, decalcified, hard tissue histology techniques. Rabbit caivarias defects treated with Neo-Os® particles and polytetrafiuoroethyiene (Gore-tex®) membrane, healed by in growth of woven bone from the defect margins and by formation of bony islands within the defect area. Finally, the defects were treated with woven and lamellar bone.

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Papillon Lefevre Syndrome (PLS) is a rare disease, associated with the early onset periodontal break down in deciduous and permanent dentition.The etiology of PLS is not exactly determined but recently, mutation in catespin C gene, as a genetic basis for the disease, has been established. The aim of this study was to investigate the HLA status in patients affected with PLS. In this research, the frequency of HLA-I and HLA-DR in 9 PLS patients (Belonged to seven unrelated families) were compared with 37 healthy people (controls). Fisher exact test was used for data analysis. The results indicated that the frequency of HLA-B18 was significantly higher in the patients’ group, compared to the control group(P<0.05). The present study, based on the serological methods, is the only existing controlled study regarding PLS. However, in order to get accurate results, a molecular technology with more samples is required.

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Cancer is considered as one of human's complications, particularly in oral and maxillofacial region which leads to undesirable effects and sometimes endangers individual's life. The aim of this study was to investigate the frequency of maxillofacial malignant tumors, during 13 years, (1985- 1998),in Hamedan. Three hundred and eighty - six records of biopsies were selected from the private files of physicians, 7 private and governmental pathological centers and other educational and research organizations in Hamedan. After observing the samples by oral pathologist, they were presented as the statistical population for this retrospective study. The highest rate of biopsies was observed in the sixth (42.7%), seventh (39.6%) and third (10.6%) decades. The average age was 43.5 years, for women and 1.52 45.5 for men. The ratio of men to women was . The oldest patient was a 91- year - old man with malignant melanoma, while the youngest was a 3-year-old girl with Burkit lymphoma. The commonest site of involvement was nasal region (17.3%) and the anterior neck triangle showed the least common tumoral site (2.3%). The commonest tumor, observed in this study, was BBC (41.4%) and the least common was malignant fibrous histocytoma (0.2%). Baso cellular and epidermoid carcinomas have been the commonest cancers in this investigation, while lymphoma and salivary galnd cancers have been placed as the second ones. The results of this study showed that the lower lip and tongue are considered as the commonest sites for cancer.