Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns

Sve češća potražnja za estetskim restauracijama rezultirala je povećanim korištenjem potpuno keramičkih dentalnih nadomjestaka, primjerice onih od cirkonijeva oksida. Time se pojavljuje izazov osiguravanja vezne čvrstoće ortodontskih bravica na različite keramičke materijale. Na snagu veze može utjecati vrsta bravice, odnosno materijal od kojega je izrađena i površina njezine baze ili način retencije. Svrha rada: Željela se provesti komparativna analiza posmične čvrstoće metalnih i keramičkih ortodontskih bravica zalijepljenih na cirkonij-oksidnu keramičku površinu kakva se nalazi na protetičkim nadomjestcima, te procijeniti način loma tih dviju vrsta ortodontskih bravica. Materijali i metode: Pripremljeno je 20 uzoraka/polukrunica od keramike na koje su zalijepljene ortodontske bravice – 10 metalnih i 10 keramičkih. Posmični test obavljen je u univerzalnoj kidalici s opterećenjem uzrokovanim klipom oštrog vrha koji se kretao pri fiksnoj brzini od 1 mm/min do loma. Sila potrebna za odljepljivanje bravica bilježena je u Newtonima, nakon čega je posmična čvrstoća izračunata u MP-ima. Osim toga, uzorci su analizirani pod digitalnim mikroskopom kako bi se ustanovio indeks ostatka ljepila (ARI). Statistički podatci obrađeni su t-testom, a razina značajnosti postavljena je na α = 0,05. Rezultati: Pokazali su da je vezna čvrstoća metalnih bravica vezanih na cirkonij-oksidne krunice veća u usporedbi s keramičkim bravicama sa statistički značajnom razlikom. Tijekom istraživanja dvije keramičke bravice su djelomično ili potpuno oštećene. Zaključak: Čini se da metalne bravice u usporedbi s keramičkima stvaraju jaču vezu s cirkonij-oksidnim površinama zbog boljeg načina retencije. Keramičke bravice su i krhkije tijekom uklanjanja.An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations. Bond strength can be affected by bracket type, by the material that brackets are made of, and their base surface design or retention mode. The aim of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Material and methods: Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been tested by Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Results: Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared to those of ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Conclusion: Metallic brackets, compared to ceramic polycrystalline brackets, seemed to create stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding

Influence of different orthodontic brackets and chemical preparations of ceramic crowns on shear bond strength

BackgroundBonding to ceramic restorations remains a major challenge to orthodontists, especially due to an increasing number of adults seeking orthodontic treatment.AimsThe objective of this research was to investigate the influence of two chemical methods used for surface conditioning of ceramic crowns, on shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to ceramic surfaces.Methods The study was conducted on 48 prepared specimens of metallic and ceramic orthodontic brackets bonded to ceramic crowns, conditioned with two different etching materials: hydrofluoric acid (HFA), or phosphoric acid, and subsequently, silane. SBS was tested using Universal Testing Machine. The samples were analysed using Scanning Electron Microscope, to determine adhesive remnant index (ARI). Statistical data was processed with ANOVA, and ARI was evaluated using x2 test, with level of significance α=0.05.Results SBS values of the groups etched with HFA and silane, compared to the groups etched with phosphoric acid and silane, are not significantly increased. However, ceramic brackets show significantly higher SBS values than metallic brackets.ConclusionBoth types of ceramic surface conditioning procedures have similar features and provide strong enough SBS values to realize the orthodontic treatment. Also, the assumption that only the type of bracket significantly affects the SBS value can be accepted

Influence of different orthodontic brackets and chemical preparations of ceramic crowns on shear bond strength

Background Bonding to ceramic restorations remains a major challenge to orthodontists, especially due to an increasing number of adults seeking orthodontic treatment. Aims The objective of this research was to investigate the influence of two chemical methods used for surface conditioning of ceramic crowns, on shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to ceramic surfaces. Methods The study was conducted on 48 prepared specimens of metallic and ceramic orthodontic brackets bonded to ceramic crowns, conditioned with two different etching materials: hydrofluoric acid (HFA), or phosphoric acid, and subsequently, silane. SBS was tested using Universal Testing Machine. The samples were analysed using Scanning Electron Microscope, to determine adhesive remnant index (ARI). Statistical data was processed with ANOVA, and ARI was evaluated using x 2 test, with level of significance α=0.05. Results SBS values of the groups etched with HFA and silane, compared to the groups etched with phosphoric acid and silane, are not significantly increased. However, ceramic brackets show significantly higher SBS values than metallic brackets. Conclusion Both types of ceramic surface conditioning procedures have similar features and provide strong enough SBS values to realize the orthodontic treatment. Also, the assumption that only the type of bracket significantly affects the SBS value can be accepted