Journal of Dental Medicine
Year:2002 | Volume:14 | Issue:4 (29)|Papers Count:9

The purpose of this study was to investigate the soft tissue profile changes of the lower face following premolars extraction and incisor retraction. In order to do that, pre-and post treatment lateral cephalometric radiographs of 40 female orthodontic patients, with cl. II div. I malocclusion (22 patients) and bialveolar protrusion (11 patients) were analyzed. At beginning of orthodontic treatment, their mean age was 18.10 years, ranging from 15-24. All cephalometric radiographs were analyzed by a conventional and confirmed method called "combination analysis". The findings revealed that "lip tension" is a significant factor in soft tissue response to orthodontic treatment, so that in patients with lip strain, nasolabial angle increase was significantly more that those without lip strain. Moreover, regarding the increase of vermilion thickness of the upper lip, a significant difference was observed between two groups. In patients with lip strain, following premolars extraction and incisors retraction, lip strain was reduced or eliminated and upper lip vermilion thickness increased, following incisors retraction, the slope of nasal inferior border, in the group with lip strain, was reduced, while in the group without lip strain, this slope increased.

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 11 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 (P<0.05). 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 (P<0.05). 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.

Pain reduction and surgical wound healing enhancement have several advantages. Wound healing is a complex and organized phenomenon. During this phenomenon, definite and harmonized processes such as: reconstruction, immigration parenchyma and connective tissue cells proliferation and re-construction of gingival connective tissue take place. Studies show that lower power laser (He-Ne) can induce different biological changes in cells through biochemical mechanisms. Considering the therapeutic effects of (He-Ne) low power laser radiation on healing processes, cell proliferation, connective tissue fibers and finally the acceleration of gingival wound healing were studied. This study was done on 50 mature and healthy rats with the average weight of 250 to 300 grams, and 3 to 4 months old. After anesthesia, maxillary wounds, with the same size, were made in all samples and they were randomly divided into control and test groups. After surgery, rats of test group received laser radiation with the value of 5 mJ/cm2 every day for a period of 5 days. And on the 5th day, they were killed. Gingival biopsy was performed and histological study was done. The number of fibroblasts, collagens, endothelial cells and blood vessels were counted. In test group, the granulation tissue was more active and the edema and inflammation were lesser than those of the control group. Data were analyzed by t-test method and P<0.05 was significant. So, it is concluded that periodical radiation of (He-Ne) low power laser has an important role on surgical gingival wounds.

Posterior composite restorations, due to polymerization contraction, result in microleakage. Different methods have presented to reduce this phenomena. The aim of this study is to evaluate the effects of flowable and condensable composites to reduce microleakage. Seventy extracted human teeth were prepared with proximal class II cavities with gingival margin 1 mm below CEJ. The teeth randomly were divided into 7 groups. Groups I & II were restored with a dentin bonding (DB) agent plus a Prodigy condensable (Kerr Co.) composite, placing incremental or bulky, respectively. In groups II, IV, V a dentin bonding agent was applied and then cavities were restored with Tetric flow composite resin as a base plus either a hybrid composite (Tetric ceram, Vivadent Co.) or a Prodigy condensable composite (Cond), placing bulky or incremental. Groups VI and VII were restored with a resin modified glass ionomer (GI) (Fuji II Lc Co.) as a base plus either Prodigy condensable or Tetric ceram. Restorations were polished, thermocycled, and immersed in 0.3% basic fushin. After that samples were sectioned and studied under a stereomicroscope to evaluate dye penetration. Results showed that all restorations showed some degree of microleakage and according to kruskall- wallis statistical analysis, there were not any significant differences between all groups (P=0.051). Then fore pair comparison, between groups, Mann-Whitney analysis was used and no statistical difference was observed. However, GI+ DB+ Tetric group showed the least microleakage and DB+ Cond (bulk) the most one. Due to lack of any statistical difference among different materials methods, it is concluded that no method or restorative material have been able to eliminate microleakage in margins completely yet, and using a flowable composite resin, in place of resin modified glass ionomer or using a condensable composite, instead of conventional hybrid composites, do not have any effect on microleakage reduction.

The goal of this investigation is to compare the extent of fluoride uptake by sound enamel following application of two commercial mouthrinses containing sodium fluoride (0.2%) and a topical gel containing APF (1.23%) produced in Iran with those of foreign standardized ones. Sixty extracted premolars were used. Each tooth was divided into two lingual and buccal halves, one half as control, the other one as experimental. Enamel biopsy technique (two- step acid etching) was used to determine the concentration of fluoride and calcium in each sample. For data comparison and fluoride uptake estimation, the depths of layers with the use of linear regression analysis were standardized to 25 and 50µm. The analysis showed that in Iranian mouthrinse no. 1, there is linear correlation between fluoride concentration and enamel depth, in both control and experimental group at the first and second layers, while, in other groups, this correlation was observed just at the first layer (superficial enamel layer). The greatest fluoride uptake was seen at Iranian mouthrinse no.2 and the least was seen at foreign mouthrinse no. 3. From among two APF gels, the greatest uptake was observed at gel no. 1 (Iranian). The results showed that all three Iranian products increase fluoride content of enamel, moreover the level of fluoride uptake, while applying Iranian products, in comparison with foreign ones, shows considerable increase.

Epidemiologic studies have shown that caris or "infective damage of hard tissues in teeth" are the most common type of infection in human. In Iran, a few studies have investigated this hygienic problem, but no practical results have been defined yet. In this research, the conditions of the first upper and lower permanent molars (it contains four minor variables), have investigated. For this reason, in a descriptive analytic study, which was of retrospective and cross- sectional type, one thousand files were chosen systematically. The data were analysed by SPSS packages. The mean values of DMFT for permanent first molars were 3.47±0.50 (MT=1.23, FT=0.86, DT=1.38).  The number of extracted teeth in mandible was moer than maxilla and the number of untreated caries teeth in maxilla was more than mandible (P<0.001). DMFT ratio of the first molars to total DMFT, was approximately 29%, which indicates that caries and that complications on the first molars, make the main part of the overall DMFT. Therefore, hygiene training, preventive methods and the improvement of ecomonical status seem necessary in dental services.

Melanoma is a malignant tumor that originates from melanocyte cells. Its oral type is rare. The goal of this investigation was to determine the prevalence of oral malignant melanoma in Iran, as determined by age, sex and location. This research reviewed 623 cases of oral and non-oral malignant melanoma in Immam-Khomeini hospital, Mearaj cancer institute and department of oral pathology of dental faculty, Tehran University of Medical Sciences in a period of 19 years from 1981-1999. The results showed that 54 cases of biopsy lesions were melanoma of oral cavity that included 7.8% of these lesions. The mean age incidence of oral melanoma was 55.5(between 26-86 years). The most prevalent sites were palate (37.1%) and alveolar mucosa (20.4%) and less common sites included floor of mouth, buccal mucosa and tongue.

Whenever the first permanent molar is extracted or its long- term prognosis is poor, before taking any steps, a full clinical and radiographic evaluation associated with patient’s dental models investigation is necessary to determine the following cases: The quality and quantity of dentition, teeth missing, occlusion, buds position, orthodontic problems, the level of parents and patient cooperation for future long term orthodontic treatment and finally patient’s oral hygiene. On the basis of this information, a decision is taken about the first permanent molar extraction with poor prognosis, either of balancing or compensatory type, especially when future orthodontic treatment is improbable. The aim of this article is to explain the principles of time and sequence of first permanent molar extraction.