[Bond strength of metal brackets to enamel with a Russian adhesive complex: an in vitro study]

BACKGROUND

The era of using adhesives to fix brackets began in the 70s of the last century. There are eight generations of foreign-made adhesive systems for the restoration of teeth. However, until now, in orthodontics, the development of domestic adhesive systems with improved properties of adhesion of brackets to tooth enamel still important, especially in the posterior teeth.

OBJECTIVE

The purpose of this work was to study the shear strength of fifth generation domestic adhesive between metal brackets and the enamel of molar teeth in laboratory conditions.

MATERIAL AND METHODS

The study included 17 specimens of extracted maxillary molars embedded in acrylic resin blocks. Brackets from G&H Orthodontics (G&H Wire Company, USA) were fixed to the tooth enamel using the domestic Compofix (ortho) set. The enamel was treated with etching gel (37% phosphoric acid) for 30 seconds. Then the gel was washed off with water and the surface of the enamel was thoroughly dried. A primer was applied to the prepared surface with an applicator, inflated with a weak air flow for 5-10 seconds and photopolymerized for 20 seconds. The surface of the bracket was treated with degreaser, then a thin layer of adhesive was applied, and the sample was fixed to the enamel. Excess material was removed with an applicator. The samples were photopolymerized for 20 sec. Then, the shear bond strength of the adhesive was determined according to the method of GOST 31574-2012 on a (Zwick/Roell Z010 testing machine, Zwick, Germany).

RESULTS

The shear strength of the adhesive joint obtained during the test is 13.54±1.01 MPa, the average value of the index of adhesive residues on the surface of the bracket was 23%±4%, which corresponds to the standard average values according to GOST.

CONCLUSION

The tested domestic adhesive system of the fifth generation can be recommended for the practical work of an orthodontist.

[Evaluation of the effect of sodium hypochlorite gel on composite bonding strength to enamel of primary teeth after salivary contamination: in vitro study]

OBJECTIVE

The study investigated the effect of 2%s odium hypochlorite gel application after post-etching salivary contamination on composite bonding strength to primary teeth enamel.

MATERIAL AND METHODS

The sample consisted of 79 primary human teeth that were extracted no more than one month ago. The sample was randomly divided into four groups: (1) the control group (A) comprised 10 primary teeth, and composites were applied in the traditional manner without any salivary contamination; (2) the second group (B) consisted of 23 primary teeth in which salivary contamination was conducted after etching followed by re-etching and follow-up; (3) the third group (C) comprised 23 primary teeth in which saliva contamination was done after etching followed by washing, drying, and follow-up; and (4) the fourth group (D) comprised 23 primary teeth, in which salivary contamination was conducted after etching followed by application of sodium hypochlorite gel and follow-up. The samples were tested using the Testometric Tensile Strength Device (Testometric M350-10 kN, Testometric Ltd., UK) to measure the composite bonding strength to enamel of primary teeth.

RESULTS

The arithmetic mean strength values in the research sample were ordered as followed: (A=13.39 MPa) > (D=11.82 MPa) > (C=8.07 MPa) > (B=6.15 MPa). The application of sodium hypochlorite gel after salivary contamination significantly improved the composite bonding strength to primary teeth enamel when compared with re-etching or only washing and drying.

CONCLUSION

15 s exposition of sodium hypochlorite gel with subsequent rinse and drying is recommended in case of saliva contamination of etched primary tooth enamel surface.