Vol 21 No. 1

J Bagh College Dentistry Vol.21(1), 2009 Assessment of consistency …
Compressive strength test: Specimens of the
base materials with or with out CO 2 laser
treatment were prepared as cylinders of 4mm in
diameter and 6mm in length which prepared by
using a stainless steel mold and kept in water bath
at 37±1 0 C and 90-100% relative humidity at two
intervals: 24 hours and 1 week (7days) after
mixing .The compressive strength were
determined by using compressive strength testing
machine at speed of 1 mm/minutes, the load was
applied on the long axis of the specimens .The
compressive strength were measured for each
specimen by detecting the force that caused early
sign of fracture of the specimen.
RESULTS
Consistency test: It was found that different
consistencies of base materials produce a discs of
varying sizes that amount of the powder in
milligram which can be mixed with 0.5 ml of
polycarboxylic acid to produce a consistency
giving a disc of 33cm ±1mm in diameter were 350
mg for the group I and 300 mg for the group II
and 400mg for the group III as shown in Table 2
and figures 1,2.
one day (Table 5)showed that there was statistical
significant difference between most compared
paired groups except when we compare the group
II and group III also we compare group VI with
group VII showed the was no statistical
significant difference.
mean disc diameter of the mixed base materials cm
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0 100 200 300 400 500 600 700
powder weight of the base materials (gm)
group I
group II
group II
Figure 1: Relation between consistency (diameter of disc
of the mixed base materials) and weight of powder of the
base materials mixed with 0.5 ml polycarboxylic acid.
400
350
±0.087
±0.05
±0.0289
I
250
Table 2: Relations between the diameter of the mixed
Milligrams /0.5 ml 200
base materials and the weight of the powder that mixed
150
with 0.5 ml of polycarboxylic acid (liquid).
100
Weight
50
Disc mean Disc mean Disc mean
of
0
diameter (cm) diameter (cm) diameter (cm)
group I group II group III
Powder
of Group I of Group II of Group III
The manufactured base materials
No. (mg)
1 200 3.7 ±0.05 3.8 ±0.1 3.85 ±0.1 Figure 2: Weights of powders (mg ) of the
2 250 3.5 ±0.05 3.6 ±0.05 3.75 ±0.08 experimental(manufactured) base materials
3 300 3.2 ±0 3 ±0.05 3.65 ±0.09 mixed with 0.5 ml of polycarboxylic acid to
4 350 2.9 ±0.09 2.7 ±0.04 3.42 ±0.03 get disc diameter of 3 cm (standard
5 400 2.3 ±0.07 2.4 ±0.05 3.13 ±0.03
consistency).
6 450 2.1 ±0.25 2.35 ±0.05 2.86 ±0.06
7 500 1.9 ±0.13 1.8 ±0.09 2.65 ±0.1
±4.36
90
8 550 1.6 ±0.1 1.65 ±0.05 2.42 ±0.03
±4.03
80
±2.33
±2.52
9 600 1.3 ±0.13 1.4 ± 0.172.1 ±0.06
70
±2.41
±3.59
±2.34
± 2.09 ±3.8
60 ±1.75
±2.57
10 650 1.1 ±0.05 1.2 ±0.05 1.72 ±0.03
±2.07
Compressive strength test: The result showed that
the zinc phosphate cement in this study has the
highest values of the compressive strength at both
periods at the end of one day and the end of one
week while the group II has the lowest values at
both periods at the end of one day and the end of one
week as shown in figure 3. One-way ANOVA test
for the groups tested at the end of one day(Table
3) and One-Way ANOVA test for the groups
tested at the end of one week (Table 4)showed
that there was statistically significant difference
among the groups. LSD statistical test to compare
between each paired groups tested at the end of
Compressive
strength(MPa)
50
40
30
20
10
0
300
mgs of powder/0.5 ml liquid
±2.35
±2.78 ±1.84
±2.32
group I group II group III group IV group V group VI group VII group VIII
The groups of the base materials
Compressive strength at end of
24hours
Compressive strength at end of one
week
Figure 3: Compressive strength of all tested
groups at the end of first day and end of first
week.
LST statistical test to compare between each
paired groups tested at the end of one week
showed (Table 7) that there was statistical
significant difference between most compared
paired groups except when we compare the group
Restorative Dentistry
30