Surface texture and composition of titanium brushed with toothpaste slurries of different pHs.
OBJECTIVE
This in vitro study characterized the surface texture and composition of titanium brushed with toothpaste slurries of different pHs, and thereby elucidated mechanochemical interactions between the metal and abrasive material in dentifrice.


METHODS
Two fluoride-free toothpastes, which contained crystalline CaHPO(4).2H(2)O and amorphous SiO(2) particles as abrasive, were mixed with acidic buffers to provide slurries of pH 6.8 and 4.8. Specimens were cast from CP Ti, mirror-polished, and then toothbrushed at 120strokes/min for 350,400 strokes under a load of 2.45N. Specimen surfaces were characterized by means of SPM and EPMA. The obtained data were compared with the already reported results of water-diluted alkaline slurries. SPM data of each paste were analyzed using one-way ANOVA, followed by post hoc Tukey test.


RESULTS
Irrespective of toothpaste, neutral slurries, as with alkaline slurries, yielded a chemically altered surface with rough texture, whereas acidic slurries formed a chemically clean surface with relatively smooth texture. Mechanochemical polishing effect might be mainly responsible for the cleanness and smoothness.


CONCLUSIONS
Acidic slurry-induced smooth surface may minimize plaque formation. However, the augmentation of released titanium ions may be adverse to the human body. For evaluation of toothpaste abrasion effects on titanium, paste slurry pH should be taken into account.
Division of Biomaterial Science, Graduate School of Medical and Dental Sciences, Niigata University, Gakkoucho-dori 2-5274, Niigata 951-8514, Japan.
Awlad
A
Hossain
Seigo
S
Okawa
Osamu
O
Miyakawa
D000143:Acids; D000468:Alkalies; D002021:Buffers; D002130:Calcium Phosphates / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003461:Crystallography; D003764:Dental Materials / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014099:Toothbrushing / Q000295:instrumentation*; D014100:Toothpastes / Q000737:chemistry*; D014783:Viscosity; D014867:Water / Q000737:chemistry
D000143:Acids; D000468:Alkalies; D002021:Buffers; D002130:Calcium Phosphates; D003764:Dental Materials; D014100:Toothpastes; D014867:Water; D012822:Silicon Dioxide; C020243:calcium phosphate; D014025:Titanium