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Advisory Committee Chair

John O Burgess

Advisory Committee Members

Nathaniel C Lawson

Amjad Javed

Eleazer P Duncan

Augusto A Robles

Document Type

Thesis

Date of Award

2018

Degree Name by School

Master of Science in Dentistry (MScD) School of Dentistry

Abstract

Objectives: Loss of post retention is the leading cause in the cemented post. There is no good method of bonding a fiber post in a post space with resin cements because adhesive cementation into a prepared post space is difficult- due to an inability to place, dry and light cure the adhesive and the cement. A new post system (iLumi) that transmits light to the apex of the post has recently been developed. We want to know if this system will improve post retention in each section (coronal, middle and apical) of the prepared post space and if this curing improves resin penetration of the cured adhesive into the dentin tubules. Methods: Roots of freshly extracted mandibular bicuspids without caries, cracks or defects were observed under Keyence microscope and they are selected. Radiographs were made in the B-L and M-D direction to exclude teeth with abnormal canal shapes. Only teeth with a root length greater than 11mm were included. Roots were instrumented with K-Flex hand files (# 15 to #40), irrigated with normal saline and obturated using AH26 sealer and gutta percha. A 9mm post space were prepared in each tooth by removing gutta-percha with a post space drill. Teeth were divided into 5 groups. Digital radiographs were made to confirm gutta-percha length at the apical level and to confirm post fit. Fiber posts were cemented following manufacturer’s instructions under an applied constant load and stored (37°C/48 hours /distilled water). Using a low-speed diamond disc three-2 mm sections (cervical/middle/apical) were produced and stored (normal saline /37°C/24 hours). The sectioned tooth were etched with phosphoric acid for 15 sec, rinsed with tap water and Prime and Bond Elect adhesive was applied to the post and the canal space. Calibra Ceram resin cement was placed in the canal. The Bonding agent, Post and the cement were cured at a same time with a light curing (Elispar 3M ESPE S10/1020Mw/cm²) following manufactures’ instructions and stored (37°C/48 hours/distilled water). The specimen were placed in special fixture and a tensile load applied until failure Universal testing machine (INSTRON_5565O). Data were analyzed with one-way ANOVA and two post-hoc tests and Dunnett test to compare multiple groups to a single control group and Tukey HSD test to determine inter group differences (significant set at .05) by statistical analysis. Results: The results show that without light cured on both adhesive (Prime and bond elect) and cement (Calibra Ceram) dropped the tensile strength in each section of the canal (coronal, middle, apical) of the tooth compared to light cured on both adhesive and cement. This shows that the tooth has more chances of failures and debond very easily. Light cured only on adhesive (Prime and bond elect) and not on cement (Calibra Ceram) shows there is increase in tensile strength compared to light cured on both adhesive and cement, but no significance difference between coronal and middle section of the canal of the same group, but it shows an increase tensile strength in the apical section of the canal showing high retention. This shows that the adhesive when its light cured has a good retention and less changes of debonding. Conclusions: The applied tensile test results obtained from all specimen groups measured post retention in three different sections of the canal. Two cements were used in this study to determine whether the post would transmit adequate light energy to the apical portion of the root to polymerize the apical section well enough to equal the bond produced with a light cured dual cure cement. The different group were used to determine whether adequate light energy would be transferred from the post to polymerize the adhesive and if enough light energy would be used to polymerize the adhesive and the resin cement (Light cured Dual cure cement are stronger= higher bond strength). If any section of the canal produces different results this will allow us to concentrate our investigation on why the values are lower in that section of the root. This study aims to enhance our understanding to see if the light energy is transmitted from the post to the coronal, middle, apical section to provide polymerization of the adhesive and the post, that is what will produce different post bond strength in different sections. KEYWORDS: iLumi fiber post, Adhesive, Resin cements, Pull out Test, Keyence.

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