INTRODUCTION: Despite of the significant improvement, methacrylate-based composites still exhibit polymerization stress forces, which could lead to damages in adhesion to tooth structures and microleakege, postoperative sensitivity and secondary caries. The aim of this study was to compare the microleakage at the interface between cavity walls and giomer and silorane-based composite material restorations.
Summary Тhе use of pins in restoration of large cavities with esthetic resin materials appear in the dental literature after 1970 and there are less than 20 publications, focused around restorations of class IV cavities. The aim of the present study is to test the role of pins in the fracture resistance in class IV restorations with resin materials. Materials and methods: 68 matured human upper and lower sound front teeth are included in the study. The groups are upper incisors, lower incisors, canines with or without pins. All cavities are filled with the same resin material, technology and Prime bond NT. Termocycling: 30 days in 30ºС, 100% humidity, 60 days in 100% humidity 2Х12 hours at 35ºС and 40ºС and 100 dry cycles, 20 seconds each in the following order - 45ºС ± 3ºС, room temperature, 5ºС, room temperature, two series, 50 each with two days between in Cultura incubator of Viva Dent 55ºС and ice. Machine for vertical load testing ZD 10/90, load in Newtons (N), from 20 N to 1275 N, speed 0.5 mm/ min, displacement from 0.1 to 1.2 mm. Type of fractures observed: adhesive, cohesive in dentine and in resin material, mixed. Results: The highest proportion of fractures observed was in front teeth with large cavities and with pins, low loading (493-503N). Front teeth with large cavities without pins have better resistance and lower proportion of fractures (488-526N). Canines are more resistible with pins and less without. Lowest resistance is found in lower front teeth when pins are present. Conclusion: In class IV restorations when tissue loses are less than 2/3 of the incisal ridge pins can decrease the fracture resistance of the teeth.
Summary Overhangs from different restorations are an iatrogenic error with different results, short and long term consequences related to bone changes and periodontal diseases. Amalgam “tattoos”, idiopathic subgingival hypertrophy, marginal periodontitis and bone reductions in the intradental septum are major problems. The aim of the present study is to evaluate the frequency of traumatic restorations in distal teeth and clinical criteria, related to the x-ray findings. Evaluating criteria, for repairing the overhangs or for replacement of the restorations, is also a goal. Three hundred and sixteen - 316 patients from both sexes, 632 dental x-rays with 948 distal teeth and 632 restorations, at least two radiographs for each patient, were analyzed. Overhangs are classified in three groups: small, middle and large. In the criteria bone changes from the overhangs are analyzed separately from the existing or nonexisting bone changes from a generalized periodontal diseases. The frequency of iatrogenic changes in this cohort group is 10.6% from 632 restored teeth. This is a relatively small number compared with the other published studies. These overhangs are on distal teeth in sound teeth arches which makes them difficult for corrections. The evaluated criteria for replacement based on x-ray findings and clinical experience includes: operative and nonoperative corrections, restoration replacement, perio- and endo-therapy and follow up terms for secondary caries.
Introduction: Knowledge of endodontic microbiology and microbial organization in the root canal system is important for understanding the disease process and for establishing effective antimicrobial therapeutic strategies.The purpose of this survey is to summarize the knowledge of 5-year Bulgarian dental students about endodontic infections and their treatment.Materials and Methods: The survey includes students from FDM-Sofia who were asked to answer 11 questions online. The questions relate to species characteristics and microbial count of microorganisms in infected root canals in primary and persistent infections, apical periodontitis and overtreatment. Additional information on the respondents' age and gender has been collected and the data has been analyzed using descriptive statistic.Results: Ninety-three students participated in the survey, 31.52% of whom reported that over 300 microbial strains could be isolated from infected root canals. In apical periodontitis 8.7% reported 20-40 strains. 47.83% indicated that the microbial count in an infected root canal in a primary endodontic infection is 10 5 . Streptococcus spp. is indicated as the main reason for persistent infections by 53.26% and Enterococcus faecalis by 25%. 40.22% have chosen Streptococcus spp. as the primary species associated with overtreatment, 27.17% have chosen Peptpstreptococcus and 19.57% -Enterococcus faecalis. 85.87% associate pain with Peptpstreptococcus and Prevotela spp. 68.48% consider plating onto agars as the main method for isolating and identifying microorganisms. The results are presented graphically and represent the percentage distribution of the answers. Conclusion:Students' knowledge of species characteristics of microorganisms in various nosological units associated with infected root canals should be increased.
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