The aim of this study To compare in vitro shear bond strength (SBS) of different
orthodontic adhesives in and rebonding metal brackets after preparing their bases
mechanically.
Material and methods:Sample consisted of 40 extracted first premolars,
randomly
divided into two groups (n=20),.Adhesive removed by tungsten carbide bur later the
brackets were rebonded. The tests were performed in a tecnotest (6kN) SBS testing
machine, at a speed of 1 mm/min.
It was found that the mean shear bond strength of Reseliencewas 19.25 MPa and that
of Heliosit orthodontic was 10.25MPa.We foundthat the mean shear bond strength of
rebonding forReselience was 13.70 and 7.95 forHeliosit.The t-test revealed that there was a
significant difference between the shear bond strength of the two groups.
We found a significant difference between bonding and rebondingfor
Reselience,while there was no significant difference between bonding and rebonding for
Heliosit.
Purpose: The purpose is to assess chairside veneering posterior stainless steel crowns with nanocomposite and to compare them with conventional stainless steel crowns as well as to evaluate parental acceptance of these esthetic crowns.
Material an
d methods: The study included 32 crowns (16 conventional and 16 esthetics that were chairside veneered with nanocomposite, Tetric Evoceram®, using Ceramic Repair ,Intro Pack, Evoclar Vivadent). The crowns were placed in 10 children. A split mouth design was used. Each participant randomly received each crown type on 2 or 4 pair matched lower molars. The crowns were evaluated after 1,3,6 months and the following parameters were assessed: oral hygiene index, Gingival index, crown marginal extension, crown marginal adaptation clinically and radiographically, proximal contact areas, interproximal bone level and facing fracture. A Likert Type Scale was used to determine parental satisfaction.
Results: All crowns were retained after 6 months. Non of the esthetic crowns had a complete face lost. The integrity of the facing was rated from 1-4 (1= no fracture, 2=less than 2 mm, 3= more than 2 mm in one surface, 4= more than 2 mm in 2 surfaces). Facing was intact in 50% (8) of the crowns after 3 months and in 37.5% (6) after 6 months. Facing fractures were rated 2, 3 in 31.25% (5) of the crowns at both 3 and 6 months, and were rated 4 in 18.75% (3) at 3 months and in 31.25% (5) at 6 months. No difference was found between the result of Gingival index, proximal contacts, crown marginal extension and crown marginal adaptation clinically and radiographically for both esthetic and conventional crowns in all recalls. Oral hygiene level had a significant effect on the gingival index after 1,3,6 months and radiographic crown marginal adaptation had a significant effect on gingival index only after 6 months p=0.034. The overall parental satisfaction with the esthetic crowns was high.
Conclusions: chairside vereering stainless steel crowns with nanocomposite can be a good way to improve the esthetics of SSC with high parental satisfaction, and with out adverse effects on gingival tissue.
