ABSTRACT
BACKGROUND: Bond strength of orthodontic composite is strongly influenced by molecular and structural mechanisms. Aim of this in vitro study was to compare bond strength of light-cure orthodontic composites by measuring debonding forces and evaluating locations of bond failure. Investigations on chemical compositions clarified adhesive behaviors and abilities, exploring effects of ageing processes in this junction materials. METHODS: Twelve enamel discs, from human premolars, were randomly coupled to one orthodontic adhesive system (Transbond XT™ 3 M UNITEK, USA, Light-Cure Orthodontic Paste, LEONE, Italy and Bisco Ortho Bracket Paste LC, BISCO, Illinois) and underwent to Shear Bond Strength test. Metallic brackets were bonded to twenty-seven human premolar, with one of the adhesive systems, to quantify, at FE-SEM magnifications, after debonding, the residual material on enamel and bracket base surfaces. Raman Spectroscopy analysis was performed on eight discs of each composites to investigate on chemical compositions, before and after accelerated aging procedures in human saliva and sugary drink. RESULTS: Orthodontic adhesive systems showed similar strength of adhesion to enamel. The breakage of adhesive-adherent bond occurs in TXT at enamel-adhesive interface while in Bisco and Leone at adhesive-bracket interface. Accelerated in vitro aging demonstrated good physical-chemical stability for all composites, Bisco only, was weakly contaminated with respect to the other materials. CONCLUSION: A similar, clinically adequate and acceptable bond strength to enamel for debonding maneuvers was recorded in all orthodontic adhesive systems under examination. No significant chemical alterations are recorded, even in highly critical situations, not altering the initial mechanical properties of materials.
Subject(s)
Dental Bonding , Orthodontic Brackets , Dental Cements , Dental Stress Analysis , Humans , Italy , Materials Testing , Resin Cements , Shear Strength , Stress, Mechanical , Surface PropertiesABSTRACT
The dental unit waters are divided in two different groups, because of their chemical and microbial composition proprieties: in the first there is the "incoming dental unit water", drinking water that arrived directly in the dental chair unit through the municipal water system; in the second there is the "waste water", that represents the whole dental unit waste water. Regarding the lack of a complete systematic review on the quality of dental unit wastewater, the aim of the current research was to systematically study the incoming dental unit water and the waste one, focusing the attention on the problem of the wastewater contamination and its regulations. MATERIALS AND METHODS: A systematic literature review of the last 17 years was conducted on the topic of dental unit wastewater. Italian and English were the languages chosen for the papers research.Studies were searched in PubMed, Medline and Cochrane, with regard to inclusion criteria. RESULTS: The investigation and analysis of the two papers group revealed the presence of many information and scientific studies on the incoming dental unit water contamination, in contrast not much in literature about dental unit waste-water. CONCLUSIONS: The results revealed that dental unit wastewater is a problem underestimated by the scientific community, with the exception of dental amalgam wastes.In Italy there is a sentence of "Corte di Cassazione Penale, sez III, sentenza 17 gennaio 2013, n 2340" that regularized dental wastewaters as industrial ones, so they are inadequate to be disposed as domestic waters; but, at the same time, there isn't a specific law that regulates this king of waste.
