INFLUENCE OF BRUSHING FORCE ON ABRASIVE WEAR OF TEETH

84
EGTRIB Journal
JOURNAL OF
THE EGYPTIAN SOCIETY OF TRIBOLOGY
VOLUME 8, NO. 4, OCTOBER 2011, 48 - 59
INFLUENCE OF BRUSHING FORCE ON ABRASIVE WEAR OF TEETH
Ramadan M. A.*, Abu Elainin H. M.**, Mazen A. A.**, Ali W. Y.**1
* Faculty of Engineering, Helwan University, Helwan, EGYPT.
** Faculty of Engineering, Minia University, P. N. 61111, El-Minia, EGYPT.
1 Current Address: Faculty of Engineering, Taif University, Al –Taif, K. S. A.
ABSTRACT
The present work aims to study the effect of the brushing force on the mechanical wear of teeth during polishing. Teeth specimens were brushed using three different types of tooth pastes. Tooth paste A contained pumice of (30 – 40) μm particle size. Paste B contained 8 wt % of hydrated silica abrasive of (10 – 12) μm particle size. Type C paste is an abrasive-free paste. The abrasives used were standard Arizona sand (ACFTD) of 0 - 80 μm and (ACCTD) of 0 - 200 μm particle size. Alumina particles of (1 - 3 μm) and sand with particle sizes of (11 – 13 μm, 15 – 20 μm, 20 – 24 μm, 28 – 32 μm and 42 – 52 μm) were used to fabricate eight different pastes. The abrasives were added at a 10 wt. % concentration. The brushing speed used in the experiments was 150 strokes/min. The contact forces used were 3 and 5 N in the presence of water.
Based on the observations in the present work, it was found that the influence of the force on the abrasive wear of the teeth increased with increasing abrasive particle size. The most pronounced influence was displayed by paste A that contaminated by abrasive of 30 – 40 μm particle size. Paste B displayed slight wear increase with increasing the acting load. Besides, abrasives of wide range of particle sizes such as air cleaner fine test dust (0 – 80 μm) and air cleaner coarse test dust (0 – 200 μm) showed lower wear than paste A. In condition of adhesion, significant wear increase was observed for paste-free abrasives. When adding abrasive to tooth paste, it is recommended to avoid the abrasive particle sizes ranging from 20 - 50 μm to reduce the excessive abrasive wear occurred during polishing the teeth.
KEYWORDS
Abrasive wear, acrylic teeth, tooth paste, abrasive, brushing force.
INTRODUCTION
Tooth wear has a multi-factorial etiology involving the interplay of attrition, erosion and abrasion, [1, 2]. When two-body abrasion occurs in the mouth whenever there is tooth-to-tooth contact, this is what most dentists call attrition. Abrasion wear may also occur when there is an abrasive slurry interposed between two surfaces, such that the two solid surfaces are not actually in contact, this is called three-body abrasion, with food acting as the abrasive agent, and occurs in the mouth during mastication. Abrasion is the key physiological wear mechanism that is present in dental materials during normal masticatory function, [3, 4]. But erosion is defined as loss of tooth structure by chemical dissolution without involvement of bacteria.