Comparative assessment of the roughness, hardness, and wear resistance of aesthetic bracket materials.
OBJECTIVE
The purpose of this study was to assess critical properties of orthodontic aesthetic bracket materials.


METHODS
Samples of polycarbonate, poly(oxy)methylene, ultra high molecular weight polyethylene (UHMWPE), and polycrystalline alumina raw material used from bracket manufacturing were subjected to: (a) profilometry for the determination of Ra, Rq, Rmax and Rz roughness parameters; (b) Vickers hardness (HV50) testing; and (c) wear resistance determined by the scratch test. The results were analyzed with one-way ANOVA and Tukey multiple comparisons test at alpha=0.05 level of significance.


RESULTS
The UHMWP and alumina specimens showed the highest roughness values for all parameters. The highest hardness, amongst the polymeric raw materials, was obtained from the poly(oxy)methylene appliances. Differences were also noted between the polycarbonate raw material of different manufacturers implying an effect from the manufacturing process. With the exception of alumina, the highest wear resistance was found for the poly(oxy)methylene specimens.


CONCLUSIONS
The results of this study reveal the variability among aesthetic plastic bracket raw materials, their reduced hardness and wear resistance relative to alumina as well as the inappropriateness of UHMWPE as alternative bracket material.
Zinelis
Spiros
S
Department of Biomaterials, Section of Basic Sciences and Oral Biology, School of Dentistry, University of Athens, Athens, Greece.
Eliades
Theodore
T
Eliades
George
G
Makou
Margarita
M
Silikas
Nikolaos
N
D000537:Aluminum Oxide / Q000737:chemistry; D003460:Crystallization; D003764:Dental Materials / Q000737:chemistry*; D004955:Esthetics, Dental; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D016910:Orthodontic Brackets; D011076:Polycarboxylate Cement / Q000737:chemistry; D011095:Polyethylenes / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D013499:Surface Properties
D003764:Dental Materials; D011076:Polycarboxylate Cement; D011095:Polyethylenes; D012117:Resins, Synthetic; C111601:ultra-high molecular weight polyethylene; C005506:polycarbonate; C010102:delrin; D000537:Aluminum Oxide