Effects of recycling and bonding agent application on bond strength of stainless steel orthodontic brackets

Abstract

Objectives: 1) to assess different methods of recycling orthodontic brackets, 2) to evaluate Shear Bond Strength (SBS) of (a) new, (b) recycled and (c) repeated recycled stainless steel brackets (i) with and (ii) without bracket base primer. Study Design: A total of 180 extracted human premolar teeth and 180 premolar stainless steel brackets were used. One hundred teeth and 100 brackets were divided into five groups of 20-teeth each. Four methods of recycling orthodontic brackets were used in each of the first four groups while the last one (group V) was used as the control. Groups (I-V) were subjected to shear force within half an hour until the brackets debond. SBS was measured and the method showing the highest SBS was selected. A New group (VI) was recycled twice with the selected method. Six subgroups (1-6) were established; the primer was applied for three sub-groups, and the composite was applied for all brackets. Brackets were subjected to the same shear force, and SBS was measured for all sub-groups. Results: There was a significant difference between the mean SBS of the sandblasting method and the means of SBS of each of the other three methods. There was however, no significant difference between the mean SBS of the new bracket and the mean SBS of recycled bracket using sandblasting. The mean SBS of all sub-groups were more than that recommended by Reynolds (17) in 1975. Brackets with primer showed slightly higher SBS compared to those of brackets without bonding agent. Conclusion: To decrease cost, sandblasted recycled orthodontic brackets can be used as an alternative to new brackets. It is recommended to apply a bonding agent on the bracket base to provide greater bond strength. Key words:Recycled bracket, shear bond strength, sandblasting, stainless steel orthodontic bracket.

A comparative study on effect of different methods of recycling orthodontic brackets on shear bond strength

“…Buchman [29] stated that when the stainless steel bracket is subjected to high temperature, chromium carbide precipitate is formed leading to general weakening of the structure. Accordingly aming for 5 seconds was used by Bansal et al [13], Bahnasi et al [10], Chetan et al [8]. So, in this study, aming was done for 5 seconds then quenched in water at room temperature and dried in an air stream.…”

“…Group I : Control (new brackets, assigned with "C") Group II : Flaming group (assigned with "F") Group III : Flaming with sandblasting group (assigned with "S") Group IV : Flaming with ultrasonic cleaning group (assigned with "U") Before bonding, the buccal surfaces of the teeth were cleaned with ne pumice powder in water using a cup [7,8,10]. The buccal surface of each tooth was etched for 30 seconds with 37% phosphoric acid gel [18][19][20].…”

“…Brackets should not be adversely affected after recycling with different methods. Previous studies have reported that recycling with aming results in shear bond strength below the recommended range of clinical need [7][8][9][10], while recycling with sandblasting gives clinically acceptable shear bond strength. [8,[10][11][12][13][14][15] SBS of brackets recycled by aming with sandblasting was reported much less in a study by Gupta et al (2.05 MPa) [12] and large value (26.94 MPa) was reported in a study by Bansal et al [13].…”

A Comparative Study on the Effect of Different Methods of Recycling Orthodontic Brackets on Shear Bond Strength

“…Before bonding, the buccal surfaces of the teeth were cleaned with fine pumice powder (DPI, New Delhi, India) in water using a cup [ 4 , 5 , 8 ]. The buccal surface of each tooth was etched for 30 seconds with 37% phosphoric acid gel (Ormco corp., Orange, CA, USA) [ 16 – 18 ].…”

“…Brackets should not be adversely affected after recycling with different methods. Previous studies have reported that recycling with flaming results in shear bond strength below the recommended range of clinical need [ 4 , 5 , 7 , 8 ], while recycling with sandblasting gives clinically acceptable shear bond strength [ 4 , 8 – 13 ]. SBS of brackets recycled by flaming with sandblasting was reported much less in a study by Gupta et al (2.05 MPa) [ 10 ], and the large value (26.94 MPa) was reported in a study by Bansal and Bansal [ 11 ].…”