All ETDs from UAB

Advisory Committee Chair

John O Burgess

Advisory Committee Members

Amjad Javed

Lance C Ramp

Nathaniel Lawson

Document Type

Thesis

Date of Award

2016

Degree Name by School

Master of Science (MS) School of Dentistry

Abstract

Objectives: To measure the tensile strength of e.max copings cemented with resin, calcium silicate and calcium phosphate cements following thermocycling. Methods: 40 extracted non-carious mandibular premolar teeth were examined and selected using Keyence microscope for no carious cracks etc.were mounted in acrylic. The teeth were placed in a lathe and prepared to uniform dimensions (22° total taper) using a flat-end tapered diamond bur (846.11.025HP, Brasseler) and a 3mm preparation height. The surface area of the prepared surface was calculated with digital microscopy. The teeth were scanned with a Cerec 3 (Sirona) digital scanner. E.max crowns were milled using Cerec 3 mill (Sirona) and sintered in a Programmat CS2 oven (Ivoclar Viva-dent). The crowns (n=10) were then cemented with Activa Bioactive (PulpDent; bioac-tive cement), Ceramir Crown & Bridge (Doxa; bioactive cement), Multi-Link Automix (Ivoclar Vivadent; self-etch resin cement), or RelyX Unicem 2 (3M ESPE; self-adhesive resin cement) cement. Monobond Plus (Ivoclar Vivadent) was applied to the e.max cop-ings in the Activa Bioactive, Multi-link Automix and RelyX Unicem 2 groups. Crowns were allowed to self-cure under a 2.5kg weight. The crowns were stored in a moist bag for 24hours at 37°C, thermocycled for 10,000cycles from 5-500°C with a 30second dwell time. The specimens were placed in a custom fixture in a universal testing machine and loaded in tension at a crosshead speed of 0.5mm/min until debonding. The retention (MPa) at debonding was determined from the maximum recorded tensile force and sur-face area of the preparation. Data were compared with a 1-way ANOVA and Tukey anal-ysis (alpha=0.05). Results: The mean values of crown retention ranged from 0.45 (Ceramir) to 1.91 MPa (Unicem). The Unicem 2 cemented copings demostrated the highest bond strength, however the bond strength was not significantly different from the other groups except for Ceramir. Conclusions: One of the bioactive cements produced statistically similar crown retention strength as both the reference resin cements.

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