In-vitro comparison of two different toothbrush bristles about peri-implant sulcus penetration

Objective: The aim of this preclinical study was to compare the ability of tapered and cylindrical bristles to penetrate the peri-implant sulcus. Methods: A full mandibular dental arch was reproduced in plaster cast. In site #3.6 a hollow glass cylinder was positioned simulating a 4 mm diameter implant and the gingival component was recreated by using dedicated silicone. A Bass brushing technique was performed from the vestibular side in humid environment. During it, the penetration of the bristles between the gum and the implant was recorded by mean of an optic fibre fixed inside the cylinder. The protocol included 5 toothbrushes per group and 10 tests per toothbrush, for a total of 50 assessments for each of the two groups. A scale of 5 grades for bristle penetration was defined: grade 0 (× < 2 mm), grade 1 (2 ≤ × < 3 mm), grade 2 (3 ≤ × < 4 mm), grade 3 (4 ≤ × < 5 mm) and grade 4 (5 ≤ × < 8 mm). From the video recordings the highest value of penetration was identified for each test. Results: The tapered bristles showed an 8 times greater penetration capacity (p = 0.001) in respect to the cylindrical bristles (multilevel analysis). The percentage of tests reaching depths ≥3 mm was 86% for tapered group and 28% for the cylindrical group. Conclusion: This preclinical study shows a clear and superior penetration capacity of the tapered bristles in respect to traditional cylindrical ones. For tapered bristles, a potentially greater hygienic efficacy around dental implants is suggested.