الفهرس 
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Abstract
Summary
The purpose of the present study was to develop a new material for pulp
capping by mixing calcium hydroxide and bismuth oxide into the powder
of Portland cement and to evaluate the physical and biological properties
of the new pulp capping material and compare all the materials with
MTA.
Part I: Laboratory study
1- Formation of the new material: by adding 20% bismuth
oxide, and calcium hydroxide with the concentrations of
10% and 25%.
2- Determination of powder/water ratio of the experimental
cements.
3- Setting time evaluation of the experimental cements.
4- pH evaluation of the experimental cements.
5- Testing the strength properties of the experimental cements,
such as
a. Compressive strength.
b. Diametral tensile strength.
c. Push-out bond strength.
The experimental cement which showed the best mechanical and
adhesive properties (PortCal I) was included in the second part of the
study (animal study) to be compared with MTA and Portland
cement+bismuth oxide.
Part II: Animal study
A total of four male mongrel dogs were selected for this study. Four teeth
in each quadrant of each of the 4 dogs were included in the study. Pulp
capping was performed by deepening of the pulpal floor till the
appearance of pulpal shadow then exposure was done using endodontic
probe. Dogs were classified into two main groups according to the
evaluation period as follow:
Group A: after 3 weeks (2 dogs/24 teeth).
Group B: after 3 months (2dogs/24 teeth).
Each of these main groups were subdivided into three subgroups
according to the capping material used:
Subgroup A1: MTA (8 teeth).
Subgroup A2: Port Cal I (8 teeth).
Subgroup A3: Portland cement + bismuth oxide (8 teeth).
Subgroup B1: MTA (8teeth).
Subgroup B2: Port Cal I (8 teeth)
Subgroup B3: Portland cement + bismuth oxide (8 teeth).
After the examination period dogs were sacrificed and the mandible
and maxilla were removed for sectioning blocks of bone containing the
experimental tooth.
Teeth were then decalcified and serial sections were selected for
histological evaluation.
Histologic analysis was performed for the following assessments
A) Inflammatory cell evaluation
B) Dentin bridge formation
C) Pulp calcification.
Under the experimental conditions tested
1. MTA showed a significantly shorter setting time among the
experimental materials.
2. pH of all materials was not significantly different.
3. Compressive strength at 24 hours and 21 days was significantly
higher in MTA and Portland cement followed by PortCal I
followed by PortCal II.
4. Diametral tensile strength at 24 hours was significantly higher in
Portland cement+bismuth oxide followed by MTA followed by
PortCal I followed by PortCal II. However, in 21 days MTA and
Portland cement+bismuth oxide showed no significant difference.
5. Push out bond strength was statistically significantly higher with
Portland cement+bismuth oxide followed by PortCal I followed by
MTA and then PortCal II.
6. Mean inflammatory cell count at 3 weeks and 3 months was highly
significant in MTA followed by PortCal I then Portland
cement+bismuth oxide.
7. Dentin bridge formation in 3 weeks 25% of the pulps with MTA
recorded partial dentin bridge while Portland cement+bismuth
oxide showed 12.5% only. No dentin bridge in PortCal I. In 3
months period MTA was significantly higher followed by Portland
cement+bismuth oxide then came PortCal I.
8. No pulp stone formation at 3 weeks period was recorded with any
of the materials. While in 3 months MTA showed no pulp stones,
while Port Cal I and Portland cement+ bismuth oxide showed pulp
stone formation.