The Repair of Preveneered Posterior SSC’s

Department of Pediatric Dentistry
Resident’s Name: Murphy Program: Lutheran Medical Center - Providence
Article title: The Repair of Preveneered Posterior SSC’s
Author(s): Yucel Yilmas DDS, PhD. Taskin Gurbuz DDS, PhD, etc al.
Journal: Pediatric Dentistry
Year. Volume (number). Page #’s: 2008. V30 No 5. 429-435
Major topic: Repairing preveneered posterior SSC’s

Overview of method of research: The study’s purpose was to determine the shear bond strength (SBS) for and to perform dye penetration (microleakage) and scanning electron microscope (SEM) evaluations of preveneered posterior SSC’s Twenty-two crowns were use in total. Eleven were repaired by one method (group 1), eleven by another (group 2) and 2 of each group were sectioned for dye analysis. All of the crowns were soaked in saliva for 30 days and then thermocycled. An occlusal force was applied to the crowns to induce a fracture.
Group 1 was repaired using a method designed by Weidenfield for veneering anterior SSC’s. An opaque cement called Panavia, and Tetric Flow composite were used. The fracture margins were prepared with a diamond bur, and an exposed metal was sandblasted, leaving the metal with frosted appearance. The teeth were etched, rinsed, dried, bonding agent was applied and set for 60 seconds, then air dried. The Panavia was then applied to mask the metal color, and the Tertic Flow was added on top.
Group 2 was prepared the same as group 1, however Monoopaque light curing opaquer and Tetric Flow was used. After the bonding agent was completed, .5mm of the Monoopaque was applied to the metal surface and cured for 40 seconds. The Tetric Flow was then applied.
The crowns were then subjected to the dye penetration and SBS test again. Bond failure was scored as adhesive failure (steel /resin interface), cohesive failure (within the facing), or mixed. Also, fractured extent was scored as no cracking, loss of one third, loss of one half, and complete loss.

Findings: The original unrepaired crowns had a higher SBS than either group. In group 1, there was a 4% reduction, and in group 2 there was a 9% reduction. These results, however, were not statistically significant. When all of the fractures were compared, again, there was no statistical significance. It should be noted that there were no adhesive failures.

Key points/Summary:
Most veneered crowns show some chipping within four years.
Dye penetration was seen in 20% of all repaired specimens. It was assumed that the bur did not create a sufficient enough micromechanical area for interlocking to occur between the original veneer material and the repair material.
The fractures observed were either cohesive or mixed. No adhesive fractures occurred.
There was statistically different ranges between group 1 and 2 in terms of fracture extent, with Group 2 being the source of this difference.

Assessment of Article: Overall a good article. Lots of researchy stuff to read through, but definitely good info. If I ever use posterior veneered SSC’s, and have to replace them, I will know how.