الفهرس 
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Abstract
Endodontically treated teeth are known to present a higher risk of biomechanical
failure than vital teeth owing to loss of tooth structure, decrease moisture content
and subsequent brittleness. Therefore, researchers and clinicians recommended
use of post and core system to reconstruct badly mutilated teeth.
This study was designed to evaluate the effect of intraradicular restorative
techniques on the strain and fracture resistance of flared endodontically treated
teeth.
A total of Thirty-five freshly extracted mandibular premolars, free of cracks,
fracture or caries and with approximate dimensional similarity were used in this
study. Teeth were endodontically treated and obturated with gutta-percha and
eugenol free sealer. Then, teeth were decoronated horizontally 2mm above the
apical point of the proximal cement-enamel junction. All samples were milled into
standardized preparation dimensions. Finally, root canal spaces for all teeth were
performed with standardized degree of flare using high & low speed diamond
burs.
Teeth were divided into five groups each of seven samples according to the type of
intraradicular restoration as follows: Group I. (control group) teeth where their
roots were restored with glass fiber posts with no over flaring. Group (II - IV)
roots were over flared using high and low speed diamond burs Group II root
restored with glass fiber posts, relined with composite resin using direct technique.
Group III roots restored with glass fiber posts associated with accessory posts
using direct technique. Group IV roots restored with glass fiber posts, relined with
composite resin using indirect technique. Group V. roots restored with glass fiber
posts associated with resin and accessory posts using indirect technique. Core build up was done using composite resin, and all specimens were prepared to
receive full veneer metal crowns.
Root dentin strain was measured with strain gauges where strain values were
obtained on root buccal surface. Following that, samples were subjected to fracture
resistance test using the universal testing machine.
The results showed that no significant difference in strain measurement were
found between the groups, while the fracture resistance test showed that teeth
restored with accessory glass fiber posts had the highest mean value followed by
control group whilst the fiber post relined with composite resin had the lowest
value.
Within the limitations of this study the following conclusions could be drawn;
1. Neither the type of intraradicular restoration nor the technique whether
direct or indirect had an effect on strain at 150N.
2. Glass fiber post relined with composite resin using direct technique
decreased strain at fracture load.
3. Using glass fiber post with accessory posts had effectively improved the
fracture resistance of endodontically treated teeth with flared canals.