Measurement of dental restorative material topography.
BACKGROUND
The tracing of peaks and valleys produced during surface profiling of dental materials are read against a mean line which can be modified in the form of a line or arc. Roughness (R) is commonly used to measure the topography of restorative materials, but the profile (P) value is also generated during the tracing and includes both roughness and waviness of the surface.


OBJECTIVE
The purpose of this study was to determine if line and arc modified tracings and R and P surface topography measurements give similar results.


METHODS
Thirty six cavities (5 x 1.5mm) were prepared in Perspex discs, restored with Fuji IX, a high strength glass ionomer cement, following the Atraumatic Restorative Treatment (ART) technique and the surface of six cavities were each treated as follows: press finger with vaseline (Va); press finger with polyacrylic acid (Aa); carving (Ca); burnishing (Bu); Mylar strip (My); polishing (Po). Topography was assessed using a profilometer which ran three equidistant tracings (3.6mm) on each surface giving a total of 18 readings for each treatment (n=6). The results of Ra, Rv, Rp, R, and Pa, Pv, Pp, P, for all 6 surface treatments were compared and analysed using ANOVA and Tukey's studentised range test with significance set at P<0.05.


RESULTS
Within R + line, R + arc, P + line and P + arc, significant differences were apparent between treatments. Pairwise comparisons showed fewer instances of significant differences between surface treatments when R + line (1 instance of significant difference) was compared to R + arc (2). P + line showed 12 instances of significant differences between surface treatments while P + arc showed no difference.


CONCLUSIONS
Both line and arc tracings gave similar results for R and either may be used in assessing surface roughness. The total deviation of the profile P showed more significant differences between treatments with line than with arc and may be a more sensitive tool when dealing with small sample numbers or subtle differences between surface treatments.
Rosen
M
M
MRC/Wits Dental Research Institute.
Grossman
E S
ES
Mickenautsch
S
S
Cleaton-Jones
P E
PE
D000704:Analysis of Variance; D003775:Dental Polishing / Q000379:methods*; D003793:Dental Restoration, Permanent / Q000379:methods*; D005899:Glass Ionomer Cements; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D016014:Linear Models; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D013499:Surface Properties
C439808:Fuji IX GP Fast; D005899:Glass Ionomer Cements