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UBC Theses and Dissertations

Effect of non-thermal plasma on the bond strength of orthodontic brackets to enamel : an invitro study Arora, Deepak


Objectives: Non-thermal plasma (NTP) has been used to modify enamel and dentin surfaces and improve the interfacial bonding of dental composite restorations. NTP is shown to cause super hydrophilic surface by decreasing the contact angle measurements and improve the quality of the adhesive - enamel and adhesive - dentin interface. We sought to determine the effects of NTP treatment on the bond strength of brackets to enamel. We investigated the application of NTP alone and in combination with phosphoric acid (PA) etching and assessed the outcomes after 24 hours and 1 month. Methods: 84 extracted pre-molars washed and disinfected were divided into 2 broad groups: No-treatment and Treatment group. No - treatment group consisted of 12 premolars on which orthodontic bracket bonding was performed without any surface - treatment except for polishing with pumice. Treatment group consisted of 72 premolars which were divided randomly into 3 main groups of 24 premolars each. These groups were Group 1: PA Etch (30s), Group 2: PA Etch (30s) + NTP (30s) and Group 3 NTP (30s). The bonded teeth were stored in water at 37° C and tested in shear mode after 24 hours and 1 month (n= 12). The fracture mode and adhesive remnant index were determined on de-bonded surfaces. SEM pictures were taken from enamel surfaces after each treatment. Results: During the first 24 hours of testing, SBS was maximum with Etch+ NTP and Etch treated group followed by NTP group ( P < 0.05). After 1 month of ageing the SBS was maximum with the Etch group followed by Etch+ NTP and NTP group ( P < 0.05). ARI scoring was higher with Etch and Etch+ NTP group. SEM pictures showed Type 1 acid etch pattern with Etch and Etch+ NTP group whereas NTP treated group showed no surface changes. Conclusions: NTP application by itself has a potential to bond orthodontic brackets however a longer ageing time will explain more about this feasibility.

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