Abstract
ABSTRACTObjective: The aim of this in vitro study was to evaluate and compare the effects of grinding, drilling, sandblasting, and ageing prefabricated teeth (PfT) on the shear bond strength (SBS) of orthodontic brackets, as well as the effects of surface treatments on the adhesive remnant index (ARI). Methods: One-hundred-ninety-two PfT were divided into four groups (n = 48): Group 1, no surface treatment was done; Group 2, grinding was performed with a cylindrical diamond bur; Group 3, two drillings were done with a spherical diamond bur; Group 4, sandblasting was performed with 50-µm aluminum oxide. Before the experiment, half of the samples stayed immersed in distilled water at 37oC for 90 days. Brackets were bonded with Transbond XT and shear strength tests were carried out using a universal testing machine. SBS were compared by surface treatment and by ageing with two-way ANOVA, followed by Tukey’s test. ARI scores were compared between surface treatments with Kruskal-Wallis test followed by Dunn’s test. Results: Surface treatments on PfT enhanced SBS of brackets (p< 0.01), result not observed with ageing (p= 0.45). Groups II, III, and IV showed higher SBS and greater ARI than the Group 1 (p< 0.05). SBS was greater in the groups 3 and 4 (drilling, sandblasting) than in the Group 2 (grinding) (p< 0.05). SBS and ARI showed a positive correlation (Spearman’s R2= 0.57; p< 0.05). Conclusion: Surface treatment on PfT enhanced SBS of brackets, however ageing did not show any relevance. Sandblasting and drilling showed greater SBS than grinding. There was a positive correlation between SBS and ARI.
Highlights
In comprehensive orthodontic treatments associated with prosthetic rehabilitation, the orthodontists need to bond brackets on temporary crowns, as the definitive restorations are usually placed after the orthodontic movement.[1,2]
Table 2 shows that surface treatment on Prefabricated teeth (PfT) enhanced shear bond strength (SBS) of orthodontic brackets (p < 0.01), unlike the ageing process (p = 0.45)
A positive correlation was observed between SBS and adhesive remnant index (ARI) scores (Spearman’s correlation R2 = 0.571; p < 0.05)
Summary
Prefabricated teeth (PfT) may be customized as temporary crowns or pontics and receive bonded orthodontic brackets. Sandpaper discs, silica carbide paper, sandblasting, laser irradiation, and burs have been used to increase SBS of orthodontic brackets.[1,2,3,5,6,7,8,9,10] In studies carried out with PfT, the use of sandblasting resulted on SBS of 5.5 MPa,[3] while a extensive wear on the buccal surfaces increased SBS up to 17 MPa.[8] Orthodontists would rather use a simple method to reach SBS compatible with the clinical needs, avoiding inconvenience for the patients and delay in the treatment
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