An In Vitro Study of the Abrasive Potential of Various Toothbrushes on the Surface of Aligner Attachments.

Background Attachments play a vital role in aligner-led orthodontic therapy, first passively through retention of the appliance and secondly, through bringing about tooth movement, by virtue of its active surfaces, to achieve treatment goals. Additionally, irregularities on the surface of attachments attract plaque adhesion. Thus the effect of brushing with different toothbrushes on the surface of attachments is an important factor to study. This would allow clinicians to better advise patients who are undergoing aligner therapy. Four types of brushes are available commercially, namely hard, medium, soft, and ultra-soft. This study analyses the interaction between the kind of toothbrush used and the wear of the surface of the aligner attachment, to understand the impact of a toothbrush on the attachment. Aim To observe the surface wear and change in the shape of the aligner attachment on brushing with four varying hardness of toothbrush bristle (ultra-soft, soft, medium, and hard) over six months to three years. Material and methods One attachment was bonded to the buccal surface of extracted premolars. One tooth with attachment was subjected to SEM analysis and the rest were divided into four groups of five teeth each, based on the type of toothbrush to be used. Brushing with hard, medium, soft, and ultra-soft toothbrushes was carried out in a brushing simulator in two cycles simulating six months, one year, 18 months, and three years of brushing. A contact profilometer was used to evaluate surface roughness before and after brushing and pre- and post-surface roughness values were compared to quantitate changes after which SEM analysis was carried out for qualitative assessment of the surface of the samples. The Shapiro-Wilks test was applied to evaluate the normality of the data, followed by the one-way ANOVA, and statistical significance was applied at p<0.05. Results At six months, the samples brushed with the medium toothbrush showed the least surface roughness (0.2±0.192) and those brushed with the ultra-soft toothbrushes showed the highest surface roughness (1.9±0.159). At one year, the samples brushed with the soft toothbrush showed the least surface roughness (0.46 ±0.31) and those brushed with the ultra-soft toothbrushes showed the highest surface roughness (2.12 ±0.12). At the 1.5-year point, the surface roughness of the samples was lowest in the ultra-soft toothbrush group (0.43±0.39) and the highest in the soft toothbrush group (1.6± 0.41). At the three-year point, the surface roughness of the samples was lowest in the ultra-soft toothbrush group (0.28 ± 0.17) and the highest in the medium toothbrush group (1.6 ± 0.31). Conclusion Ultra-soft toothbrushes have a high abrasive potential, as seen by higher surface roughness values over six months and one year. Morphometric changes were the most noticeable for attachments brushed by hard-bristled toothbrushes and medium-bristled brushes.