Although benefiting from an unprecedented technological evolution, contemporary endodontics is still characterized by the recurrence of retreatments, due to the need to solve quite frequent incidents, accidents, or even failures of primary endodontic treatment. This survey aims to assess both the etiology and the prevention methods of one of the most troublesome endodontic iatrogenies: instrument separation during root canal shaping. The multifactorial nature of this occurrence entails identifying and taking into account all the causal and contributing factors. Their significant number and the possible involvement of any of them, starting with the complexity and variability of the root canals and ending with the technical specifications concerning the nickel-titanium rotary instrumentation system being used, highlight the necessity to develop valid guidelines to avert the occurring of such an upsetting situation.
This study aims to determine whether the design of resin posts reinforced with glass fiber (FRC) and Reporfost (Angelus, Londrina, PR, Brazil) significantly improves the fracture resistance of endodontically treated teeth restored through this method.A batch of 30 maxillary monoradicular teeth (15 central incisors, 15 canines) were treated endodontically by step-back technique (apical enlargement 40-K file) sealed with Sealapex (Kerr Corporation, Orange, US) and gutta-percha by lateral condensation, cold. They were divided into two equal groups, prepared for cementing the FRC posts. The Exacto posts (Angelus, Londrina, PR, Brazil) in group 1 and the Reforpost posts (Angelus; Londrina; PR, Brazil) were cemented with dual cure resin cement Breeze Self-Adhesive Resin Cement (Pentron Clinical, Orange, US). Fracture resistance testing was performed on the crown-apical axial direction, using the Hounsfield / Tinius Olsen H1-KS, PA, USA mechanical testing apparatus. The behavior of each tooth-post assembly was recorded as a graph. The statistical analysis was done using one way ANOVA (α=0.05). The differences between the Exacto post group and the Reforpost post group are not statistically significant (p = 0.466). The maximum force recorded was 970 N and the minimum 186N. The mean force at which the fracture occurred was approximately 500N for both groups. The strain test showed that modifying the Reforpost post design did not improve the fracture resistance parameters of the tooth-post assembly through increasing the surface friction or maintaining adhesion to the walls of the root dentin.
Restoring teeth with second class cavities is a challenge in dentistry. Both the carious process and the preparation of the cavity for the dental restoration reduces the tooth resistance to the masticatory forces. It has been shown that modern aesthetic materials using an adhesive system improve the stress resistance of the restored teeth. There is a series of studies that attempted to determine the type of optimal material that would provide increased resistance to occlusal demands. In the present study we tried to determine the fracture resistance of molars with second class cavities restored with different categories of aesthetic materials. Thus, forty intact molars were divided into five groups of 8 teeth, MOD cavities were prepared and the teeth were restored with three types of materials: nanofilled composite, mycrohibrid composite and ormocer. The teeth of the first group were left unprepared, and those belonging to the second group were subjected to the preparation of MOD cavities but were not filled. Samples were subjected to compression using an Universal Loading Machine (Lloyd Instruments) and the value of the force they failed was recorded. Intact teeth showed the highest resistance to compression and those with MOD cavities prepared but not filled showed the smallest. Of the groups that benefited from restoration with filling material, the teeth restored with ormocer had the highest resistance, followed by those restored with nanofilled composite, and finally by those restored with mycrohibrid composite.
Sedentary behavior, both professional, occupational, leisure and recreational, is one of the major risk factors for cardio-metabolic health and premature mortality. But, this type of sedentary behavior can be found in many of the existing professional activities in 2021, among them being the professional activities with a medical profile in the field of dentistry: specific activities in the dentist’s office (and here we discuss about dentists and dental nurses) and activities specific in the dental laboratory (in this case, we are talking about dental technicians).
Nowadays, at work, many people spend more than half of their entire day working in a sitting position. Maintaining this position for a long period of time is a risk factor for health. The results of various studies have shown associations between maintaining a prolonged sitting position with morbidity due to chronic diseases, such as cardiovascular disease, diabetes, metabolic syndrome, obesity, etc. And, as we have already mentioned in the first part of this study, dental technicians are part of this category of staff, who carry out most of their specific activity, in a sitting position.
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