مجله دندانپزشکی دانشگاه علوم پزشکی تهران
سال پانزدهم شماره 1 (پیاپی 30، بهار 1381)

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.

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.

Nowadays, bone mass estimation, through imaging methods, is widely used in metabolic diseases diagnosis and treatment. One of these methods is called "optical densitometry" which estimates bone density by measuring the intensity of the transmitted light on different parts of a radiographic image. Digital radiography systems act similarly by determining grey levels of the image. The aim of this study is comparing two different methods of optical densitometry and a digital system densitometry known as radiovisiography. 45 samples, containing urografin with three different concentrations, were imaged, by both radiovisiogrphy (RVG) and conventional film systems. To determine the densitometry of films and radiovisiography images, optical densitometry and bone densitometry option of the RVG software, were applied respectively. Data were analyzed and compared for their reliability (repeatability) and correlations with concentration. In RVG densitometry system, the correlation with concentration is moderate (r=0.42) and intra samples and intra group reliability are 97.68% and 88.19%. Moreover, in conventional optical film densitometry, correlation with concentration (r=0.987) is high, intra samples and intra group reliability is high, intra samples and intra group reliability are 99.97% and 99.84%, respectively. According to the results, it is suggested that conventional film optical densitometry is more precise and reliable than RVG densitometry.

Various comparative studies have been conducted to investigate the effect of functional and fixed appliances in treatment of class II skeletal disorders. The aim of this study was to compare Bionator and Edgewise appliances associated with class II elastics in the treatment of class II skeletal patients, without extraction. Lateral cephalograms of 30 patients (16 girls, 14 boys), 10-13 years old, with class II div I maolocclusion, treated with Bionater and Edgewise appliances were investigated before and after treatment. SNA, SNB, ANB, " to SN, IMP A, mandibular and maxillary lengths, upper anterior facial height to lower anterior facial height, overjet and overbite were measured in each group before and after treatment. The results were analyzed by paired t- test. The magnification of linear measurements were calculated. The differences between variables in 2 groups were compared by t-test. There was no significant difference, regarding age and sex. In both groups, increase in SNB, mandibular length, and IMPA and decrease in " to SN, overjet and overbite and upper anterior face height to lower anterior face height after treatment were statistically significant. Comparing 2 groups before and after treatment showed that increase in SNB and decrease of ANB, overjet and overbite were more in Bionator group than fixed group, which were significant. Decrease in upper anterior face height to lower anterior face height, and increase in IMPA and mandibular length were more in Bionater group but the differences were not statistically significant.

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.

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.

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).

Tooth loss is a kind of handicap and losing a number of teeth makes an individual susceptible to this disability. Having knowledge about the prevalence of partial tooth loss, provides us with a better understanding of social hygiene. On the other hand, having access to such an information, students can be led properly to treat more prevalent cases. The goal of this retrospective study is to investigate the frequency of partial prosthesis classifications, among patients, referred to Shiraz dental faculty. Sexuality, tooth loss classification and its reason and the presence of additional space were studied about all patients (371 females, 205 males) from (97-98) to the end of (99-2000). The results showed that females were more than males (64.4%), the lower jaw was treated more than the upper jaw (67.9%), dental caries were the most important reason for extraction (55.5%), class I among females (28.79%) and class II mod I among males (29.73%) had the most frequency, meaning that the most cases were free end, so more attention should be paid for the education of free end partial prosthesis, however, preventive steps should be taken to retain abutment teeth.

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.

Dentinal dysplasia type 1 is a rare herediatary disease which is attributed to an automosal dominant trait. It's incidence is about 1: 100.000. Both dentition are affected with, although the involved teeth have a normal size, shape and consistency, and they are occasionally amber. The most common clinical feature, due to their extreme mobility, is malalignement and malpositioning of teeth. Such a mobility is resulted from abnormal development of root structure. In radiographs, the roots are sharp, biunt, and conic which can be absent in both dentition. Sometimes, multiple periapical radioiucences, without any carious lesion, are observed. There is no treatment for this anomaly and retaining teeth, as long as possible, is the main goal. In this article two cases dentinal dysplasia type 1 observed in one family, are reported.