Vol 5, No 1 (2008)
Proceeding Abstracts
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Objective: This study investigated the antibacterial properties of an ion-releasing resin composite (Degufill), a hybrid resin composite (InTen-S), a compomer (Compoglass F) and a resin-modified glass ionomer (Vitremer) against streptococcus mutans.
Materials and Methods: The bacteria were derived from the dental plaque and cultured on blood agar plates. Eppendorf tubes were filled by unset restorative materials. A narrow conical cavity was created in the center of each material, prior to curing and the bacterial suspension was placed into each cavity. Each tube was incubated for the selected time pe-riods of 8, 24, 48 hours and 5 days and the procedure was repeated five times. After the incubation period, the suspensions were removed and the number of viable bacteria was evaluated. The data were analyzed using two-way ANOVA, one-way ANOVA and Tukey HSD tests.
Results: After the incubation periods of 8, 24 and 48 hours, all restorative materials ex-cept InTen-S showed significant growth inhibition when compared to the control group. There was a significant difference in the number of bacterial colonies in different incuba-tion periods. The interaction between the materials and time intervals was also significant (P<0.05).
Conclusion: The method used in this study was almost successful in ranking restorative dental materials according to their antibacterial effects. InTen-S showed no inhibitory ef-fect on bacterial growth, while other materials, especially Vitremer, showed considerable antibacterial effects.
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Objective: The main purpose of this study was to develop a simple reproducible system to compare abrasive effects of three different toothpastes.
Materials and Methods: A specific mold was used to fabricate 37 samples made of po-lymethylmethacrylate. The samples were stroke by toothbrushes connected to a V8 Cross Brushing Machine in a solution of fluoridated toothpastes and distilled water. The samples were evaluated initially and also after 48 hours. The data were analyzed by one-way ANOVA test.
Results: No significant differences was found among the three types of toothpastes after 25000 strokes (P=0.427).
Conclusion: All the three toothpastes presented same abrasive properties.
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Objective: The aim of this study was to evaluate the microtensile bond strength to sound and caries-affected dentin using Single Bond and Adper Prompt-L-Pop adhesives.
Materials and Methods: Sixteen extracted human molars with carious lesions extended halfway through dentin were ground to expose the caries affected and the surrounding normal dentin. The samples were divided into two groups of eight samples each, including Single Bond (two-step etch and rinse) and Adper Prompt-L-Pop (one step self-etch). Z-100 (3M) was used for composite build-ups. The teeth were then sectioned and prepared for micro tensile bond strength test, at cross head speed of 1.5 mm/min. Data were ana-lyzed by 1- and 2-way ANOVA.
Results: Bond strengths of Single Bond and Adper Prompt-L-Pop adhesives to sound den-tin were significantly higher than to the caries-affected one (P<0.001), besides, bond strength of Single Bond to dentin was generally found to be higher than Adper Prompt-L-Pop adhesive (P<0.001).The interaction effect was not significant (P=0.116)
Conclusion: Bond strength to caries-affected dentin was compromised when one and two step adhesives were used.
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Objective: Whilst many questions and doubts still remain, today the use of dental im-plants has gained an increasing popularity amongst patients as well as dentists. The aim of this study is to analyze the survival rate in using such implants over a 10 year period.
Materials and Methods: In this study, 3050 ITI implants placed in 1000 patients with the mean age of 49.5 years (54.4% males and 44.6% females) during 1050 stages were evalu-ated for the survival rate. The present study is a descriptive, time based analysis of all the files of patients that have been treated using dental implants over a period of 10 years. General information, number of implants in each jaw, type of implant surface, type of edentulous area, time span of Prosthodontic therapy and the endurance of the implants were gathered.
Results: Incidence of failure was as low as 2% and the number of implant failures was 23 implants (0.7%). These failures were seen in 13 implants in the upper jaw of 12 patients and 10 implants in the lower jaw of nine patients. In other words, the comprehensive sur-vival rate was seen in 98% of the patients and 99.3% of the implants.
Conclusion: The use of dental implants in treatment of missing teeth is favorable regard-less of the subject's age, sex and type of the edentulous area and a very high survival rate seems feasible.
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Objective: The use of presently available dentin bonding systems has greatly reduced mi-croleakage; however, the ideal situation where the adhesive resin completely penetrates the demineralized dentin is not yet achieved. The purpose was to compare the microleak-age of fifth and sixth generation bonding agents at enamel and dentinal margins.
Materials and Methods: Class V cavities were prepared at the CEJ of thirty extracted human premolars. The teeth were divided into three groups (n=10). In group I, cavities were treated with Prime&Bond NT; in group II, UniFil Bond; and in group III, Prompt L-Pop bonding agents were used following which composite resin (Z100) was placed incre-mentally. The specimens were stored in an environment of 100% humidity, immersed in a fresh solution of 50% Silver Nitrate each for 24 hours and then placed in a developing so-lution for 8 hours. After rinsing and being sectioned buccolingually through the center of the restoration, the samples were evaluated under a stereomicroscope at x50 magnificationfor microleakage along occlusal and gingival margins. The data were analyzed using Kruskal-Wallis and Multiple Comparison tests.
Results: There wasa significant difference between the three groups. The fifth generation dentin bonding agent (Prime&Bond NT) showed the least amount of microleakage, while the sixth generation ones (UniFil Bond and Prompt L-Pop) showed higher amounts at enamel and dentinal margins.
Conclusion: Fifth generation bonding agents seem to generate better results than those of sixth generation.
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Objective: Comparing the effect of repeated opening of the container lid of two dentin adhesive systems, Prime&Bond NT (P&B NT) and iBond (iB), on shear bond strength.
Materials and Methods: Intact bovine lower incisors (n=60), fixed in acrylic were ran-domly divided into six groups (n=10). Groups I and II were set as control groups. P&B NT and iB were applied on the samples after five days a week, three times a day for two weeks of use in groups III and VI; and after four weeks of use in groups V and VI. The samples were evaluated by a universal testing-machine (Instron, cross-head speed 1mm/min) and stereomicroscope.
Results: There was no significant difference between the bond strengths in any of the three P&B NT. The mean amount of the shear bond strength for iB after 60 times of use (15.31 MPa) was significantly lowerthan that at the baseline (23.51 MPa). There was no significant difference between iB at the baseline and after 30 times of use (19.26 Mpa), and also between iB after 30 times of use and after 60 times of use. All P&B NT groups showed significantly highershear bond strengths when compared with their similar iB groups in iB.
Conclusion: Repeated use (60 times) of the all-in-one adhesive container seems to reduce dentin shear bond strength. Therefore, containers with a lower content of the same adhe-sive or a single-dose of the adhesive are preferred.
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Objective: A clinically feasible convergence angle in full-coverage crown preparations, meeting the requirements for proper retention and resistance forms, has always been a matter of interest for laboratory and clinical researches. This study aims to evaluate the angle in teeth prepared by both under- and post-graduate students at Tehran University of Medical Sciences, Faculty of dentistry, Department of Prosthodontics.
Materials and Methods: Samples consisted of 196 prepared teeth for full-coverage crown restoration by third year postgraduate and fifth year undergraduate students in the Department of Prosthodontics. Two images were obtained from each die by a scanner and both bucco-lingual and mesio-distal convergence angles were measured, by two different assessors, via Auto CAD 14 software. The data were analyzed using analysis of variance.
Results: There were statistically significant differences between the teeth prepared by un-der- and post-graduate students in mesio-distal convergence angles of all maxillary teeth, except for canines. Significant differences were found between bucco-lingual convergence angles of the maxillary canines and molars.
Conclusion: The recently recommended convergence angles are more clinically feasible compared to the classic 4 to 10 degrees that was previously suggested for all teeth. It also seems that clinical experience does not necessarily lead to a decrease in convergence an-gles during preparation.
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A 28-year-old male farmer presented with a chief complaint of itching and extreme dis-comfort on the entire maxillary and mandibular gingivae. He was diagnosed with gingival myiasis and scaling was performed on both jaws. However because of the multiple larvae, complete removal with simple curettage and scaling was not feasible, therefore flap sur-gery was performed on the maxilla. One week later the sutures were removed and healing was uneventful. The patient failed to return for the treatment of his mandibular lesions probably because the administered antibiotics had reduced his discomfort.
