JOURNAL OF DENTISTRY (SHIRAZ UNIVERSITY OF MEDICAL SCIENCES)
Year:2003 | Volume:3 | Issue:3-4 (5)|Papers Count:8

This study was carried out to estimate the DMFT and OHI-S indices and to define the occlusion type in handicapped children and the effects of the type of handicapping, sexuality, parent's education and the brushing habit on the above mentioned indices in 302 children aged 10-12 years. 70.6% of children were mentally retarded, 23.5% of them were deaf, 3.6% blind and 2.3 handicapped ones. 40.1% of our subjects were female and 59.9% were male. The mean DMFT obtained in this study, was 5.04±1.96, the mean number of decayed teeth was 4.8±2.38, the mean number of filled teeth, was 0.19±0.06 and the mean number of missing teeth was 0.06±0.22. The mean OHI-S was found to be 3.64±1.54, D-index to be 3.22±1.51, C-index to be 0.42±0.79. 83.8% of the children under study were classified as normal class I occlusion and the remaining 16.2% consisted of various malocclusions. As regards to brushing habit, it was found that 68.2% of the children studied brushed their teeth regularly, and 31.8% failed to do it. The multiple-handicapped children had the maximum level of DMFT (DMFT=8.08). As regards OHI-S and its components, the blind group had the highest level (OHI-S=5.5). The DMFT and OHI-S (and their components) levels are higher in families with five or more members (5.11 and 4.82 respectively) in comparison with those with less than five members (3.17 and 2.83 respectively). There was a significant relationship between the DMFT and OHI-S indices with the type of disability in children examined in this research.

Marginal fit of restorations is important for longevity and periodontal health maintenance. The purpose of this study was to compare the marginal fit adaptation of metal ceramic crowns in three different finish lines, fabricated with base metal alloys. 33 metallic dies were prepared in three groups of finish line: Shoulder 1350, Shoulder and Chisel. Dies were lubricated and wax patterns formed with use of a wax bath. Wax specimens were invested and cast with base metal alloy. After placement of porcelain on surface of castings, all crowns were luted with cement under a constant load. All specimens were then embedded in acrylic resin block and sectioned. The marginal fit of the crowns were evaluated by measuring film thickness of cement in the margins. The differences between groups were evaluated with ANOVA and LSD test. Statistical difference between Shoulder and the other groups was significant (P<0.001). By considering discussed advantages of 1350 Shoulder finish line for metal-ceramic restorations, this finish line is recommended for metal ceramic restorations made from base metal alloys.

The final objective of root canal therapy is to provide complete obturation of root canal system to maintain the integrity of the attachment apparatus. The material that routinely used as root canal filling material consist Gutta-percha core with combination of sealer. Different kinds of sealers are available in the market and widely used in root canal treatment. Among this the commonly used sealers are; the material with ZOE based, with resin based, with calcium hydroxide based and glass ionomer based sealers. The purpose of this an invitro study is to evaluate the sealing ability of four root canal sealers consist of ZOE and tubliseal as zinc oxide Eugene based cement, AH26 as a resin based cement and CRCS (calciobiotic root canal sealer) as a calcium hydroxide based cement. Since in Iranian Dental Schools, pure zinc oxide powder with eugenol is commonly used as sealer, a comparative study was done to evaluate the sealing ability of this cement. In this study, seventy single rooted human teeth were selected. After cleaning and shaping, the specimens were randomly divided into six groups. (4 experimental groups and 2 negative and positive groups). In experimental groups the canal were obturated with lateral condersation technique using different sealers. After obturation, the samples were cleared using Robertson method and the deepest linear apical dye penetration was evaluated by three independent evaluators. The data were analyzed by using one way analysis of variance test. The result was shown that the difference between experimental groups was not statistically significant. Whereas, the AH26 group was shown the least apical microleakage and the CRCS group were shown the most apical leakage. The result of this study was compared to the results demonstrated by others. The differences may be related to the methods of evaluation.

Making effective methods in evaluation of bone density changes are useful in early diagnosis of diseases with manifestation of bone rarefaction or destruction. These methods are also useful in determination of bone healing amount after surgery or graft procedure. In this study, capabilities of digital bone density detector software in diagnosis of bone density changes were searched. Initially, two pieces of samples from each dry human mandible were obtained and radiographed as control groups. Bony samples were decalcified partially in 90 minutes interval using nitric acid solution 15% concentration and after each decalcification period, they were radiographed. Provided conventional radiographs were evaluated by densitometer and observers. Indirect digitized images were also evaluated in similar sites by digital bone density detector software. Results of densitometer, observers and digital bone density detector software finding, were compared with each other by statistical analysis. This investigation shows more ability of digital bone density detector software in diagnosis of bone density changes. Another result was more sensitivity of provided software in comparison with conventional densitometer in diagnosis of cortical bone density changes on indirect digitized images.

The main goal of this research was to evaluate the stress produced in tooth, PDM, spongy bone, and cortical bone consequent to force application (1 N) to the crown of an upper central incisor, while the alveolar bone resorbs gradually. Four 3-dimensional FEM models were designed (ARGue 392-5) with the same form except for their alveolar bone support that represented 1, 2.5, 5, and 6.5 mm of reduction. All the output data were compared with a normal model (ARGue 391). Normal stress in palato-labial direction (dY) and two shearing stresses (Tyz, Tyx) were evaluated. A progressive increase in all stress forms were found in all of the involved tissues in gradual steps of alveolar bone loss. Based upon this study, 2.5 mm of alveolar bone loss can be considered as the limit beyond which the normal stress changes accelerate. This limit is 5 mm for the shearing stresses. There were some clinical suggestions on the manner of force application and the appliance selection, based on the findings of this study, in the article.

In this study, the relative frequency of factors, that cause the necessity for replacement of dental amalgam restorations in patients referred to Operative Department of Isfahan Dental School was clinically and radiographic evaluated (year: 2000-2001). In addition, the prevalence of diagnostic instances through clinical examination and radiographic inspection was compared. Four hundred cases were included in this study. The type of research was descriptive. Regular explorer, plain mouth mirror, dental floss and light of dental unit were utilized for clinical registration. Isolation was performed by saliva ejector and cotton roles. Bitewing radiography technique was used for radiographic inspection. Relative frequency of secondary caries, overhang, tooth fracture, amalgam bulk fracture and marginal fracture were 66.25%, 23.5%, 19.5%, 15.25%, 23.5%, and 4.5%, respectively. There was no significant difference in diagnosis overhang between the results of the clinical examination and the radiographic inspection. In other instances, clinical examination had a significant more diagnostic value. The high relative frequency of recurrent caries factor indicates the importance of proper cavity preparation, optimal material selection and accurate material manipulation, and also oral hygiene education to the patients.

Denture plaque is an important factor in the pathogenesis of denture stomatitis. Denture cleanliness is essential to prevent accumulation of plaque with its deleterious effects on the mucosa. With emphasis on patient education and preventive dentistry, a dentist must be able to recommend a denture cleanser that is effective, non deleterious to denture materials, and safe for patient use. A two part study was designed to compare the efficacy of three chemical denture cleansers (Polident, Sodium hypochlorite and vinegar) in removing and/or killing aerobic, anaerobic and yeasts cells on the dentures. In the present investigation, ten upper complete dentures worn by 53-75 years of age patients were used. The dentures were placed in the mixture of sterile D.W. and antibacterial agents (Polident, Naclo, Vinegar) for certain period of time and then examed for the presence of bacteria and Candida albicans. The following conclusions were obtained in this study:1. Polident was the most effective sanitizing agent.2. Sodium hypochlorite and Vinegar were effective in killing bacterial but less effective on Candida albicans.