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AJ de Gee, P Pallav

This page deals with the correlation of clinical data with the results from our Acta Wear Machine. 

Please note that with some studies, the correlation included several different types of materials (micro-, small particle filled, or old fashioned large particle composites, an amalgam, a glassionomer, etc.). E.g. correlation of the wear machine with study e, or g includes composites and an amalgam (two classes) and X with c includes a composite, amalgam and a glassionomer (three classes). This is important for a correlation because when all materials are of the same type, nearly any test, even if it's not a wear test, may produce favorable results. That's why McCabe's capsule shaking test is still a very useful test. If a material can be compared with similar materials, this test may give quite satisfying results in no time at no costs. 

Results

The table lists the results. The average correlation of the Acta Wear Machine (X) with these clinical studies is about 0.90. This is the average of the numbers in the top horizontal row, without the first 1. The average value of all the others is about 0.87. This means that the results from the Acta Wear Machine agree with the clinical studies about as well as these agree among themselves. 

Correlation coefficients between the studies listed below
X a b c d e f g h i j
1 0.92 0.89 0.99 0.85 0.99 0.41 0.99 1 0.96 0.97 X
1 0.86 a
1 0.98 b
1 c
1 0.98 d
1 0.98 0.96 e
1 0.47 f
1 g
1 h
1 i
1 j

Our wear machine was designed to generate wear on dental materials, so that these can be tested on their (relative) performance in (amongst others) CFA wear. 
What we do is that we test ten different materials, including a reference material, for which we normally use Dispersalloy, an amalgam. By comparison with this reference, we can say how much faster or slower each of the other nine materials wears. 

This will work only of course, when the wear in the wear machine looks enough like the food caused wear in the average person. 
We searched the literature from 1985 to 1993 for publications of clinical studies (a to j, below), in which two or more materials were tested, which had also been tested in our wear machine (table yet below). 
We have standardized the composition of the slurry accurately. The standard deviations come as low as 3 % with some materials. The standard deviations with the clinical studies are of course much greater.

The clinical studies (a to j) and the Acta Wear Machine (X)
Study   duration  
X the ACTA wear machine   55 hours
a Braem et al. 1987a 3 years
b Brunson et al. 1989   3 "
c Chadwick et al. 1991 1 "
d Freilich et al. 1992   3 "
e Lambrechts et al. 1987   4 "
f Leinfelder et al. 1986 1 "
g Lutz et al. 1985   2.5 "
h Mair et al. 1990   3 "
i Mitchem et al. 1985   3 "
j Willems et al. 1993 3 "

 

Wear data (µm) from various clinical studies (a-j) and the ACTA wear machine (X).
 
Studies
Materials X a b c d e f g h i j
Adaptic 64         173   269   216  
Clearfill Posterior New Bond 16               79    
Dispersalloy 13     32   25   29      
Estic Microfill -         34   99      
Estilux Posterior 45 45                  
Ful-Fill 40   145       86        
Heliomolar 52       52            
Ketac Fill 77*     157              
Lumifor 51                   151
Miradapt 22         39       105  
Marathon -       174           79
Occlusin 37 40   100     56   176    
P-10 22 39 145       111 74      
P-30 19       45   131   96   34
P-50 21                   30
Profile 44                 210  
* Average of early wear, long term wear and wear at pH = 5.5.