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Aim: The purpose of this research is to compare the amounts of bacteria that are extruded from their apical surfaces during the instrumentation of root canals utilising the K3XF, Protaper Gold, Edge taper Platinum, and Hyflex CM Rotary systems. Materials and methods: Sixty caries free single rooted human maxillary incisor teeth were divided in six groups of ten teeth each. Teeth in each group were instrumented until the working length with the respective rotary file system. The access cavity was made, and the pulp and debris were removed from the canals. On the device for gathering microorganisms, the teeth were mounted. The Fusobacterium Nucleatum (ATCC 25586) was used to infect the root canals, which were then dried at 37 °C for 24 hours. Group I (Control group), no instrumentation was done. Group II used hand K-files, Group III used Protaper gold, Group IV used K3XF, Group V used Edge taper platinum, and Group VI used Hyflex CM rotary file systems. In. The sample was then collected, cultured in Mueller-Hinton agar for 24 hours, and the number of colony-forming units was counted. Statistical analysis: The Kruskal-Wallis nonparametric test and Mann-Whitney U test were applied to determine if significant differences existed among the groups (P< 0.05) Results: Comparing hand K-files to the other four rotary systems, the K3XF file system extruded the fewer number of bacteria. Conclusion: Within the limitations of this study, it can be concluded that all instruments tested produced bacteria from intracanal spaces apically. However, compared to the manual method, engine-driven nickel-titanium devices extruded fewer microorganisms. Comparatively, the K3XF rotary file system extruded less microorganisms than other rotary file systems. [ABSTRACT FROM AUTHOR]

Introduction: There is an increasing trend of malocclusion among children, so it is necessary to identify the cause of the tooth wear so that the orthodontist can treat the patient accordingly. It is necessary to determine the wear patterns of different malocclusions. Therefore, the aim of our study was to compare the patterns of tooth wear among two categories of Angle's class II malocclusions, i.e. class II division 1 and class II division 2.Material and Methods: The sample consisted of 100 pretreatment orthodontic patients in the age group of 15-25 years with Angle's class II malocclusion and were divided into following two groups: (a) Group 1: 50 subjects with full cusp Angle's class II division 1 malocclusion. (b) Group 2: 50 subjects with full cusp Angle's class II division 2 malocclusion. Clinical examination of the patients for tooth wear was done supplemented with dental casts, intraoral photographs and intraoral radiographs. Then each group was assessed for severity of tooth wear according to modified tooth wear index (TWI) given by de Carvalo Sales-Peres et al. Scores were subjected to statistical analysis and the pattern of tooth wear among the two groups of class II malocclusion was compared. A correlation between the gender of the patient and the tooth wear was also determined. The level of statistical significance (p-value) was less than 0.05.Results: The class II division 1 subjects showed statistically greater wear on the occlusal surfaces of the maxillary canines, first, second premolar and first molar, and the occlusal surfaces of the mandibular first molars. The class II division 2 subjects showed statistically greater tooth wear on the labial surfaces of the mandibular central and lateral incisors, the incisal surface of maxillary and mandibular incisors, the palatal surfaces of the maxillary second premolars, first and second molars. In class II division 1 subjects, the tooth wear was significant on the buccal surface of maxillary canines, occlusal surface of mandibular first premolars and second molars in males. In class II division 2 subjects, the tooth wear was significant on the buccal surface of mandibular canines, palatal surface of maxillary central incisors in females and palatal surface of maxillary first premolars in males.Conclusions: The results of this study suggested that the two categories of Angle's class II malocclusion have different tooth-wear patterns. The wear patterns were different in both the sexes. Men showed higher occlusal wear scores than did women. The findings also suggest that tooth wear in relation to malocclusion is physiologic and is due to dissimilar interocclusal arrangement. [ABSTRACT FROM AUTHOR]