Preparation Ferrule Design Effect on Endocrown Failure Resistance
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-10-06 |
| Journal | Journal of Prosthodontics |
| Authors | Michael A. Einhorn, Nicholas DuVall, Michael Wajdowicz, John Brewster, Howard Roberts |
| Institutions | Patrick Air Force Base, Keesler Medical Center |
| Citations | 120 |
Abstract
Section titled âAbstractâAbstract Purpose To evaluate the effect of preparation ferrule inclusion with fracture resistance of mandibular molar endocrowns. Materials and Methods Recently extracted mandibular third molars were randomly divided into 3 groups (n = 12) with the coronal tooth structure removed perpendicular to the root long axis approximately 2 mm above the cementoâenamel junction with a slowâspeed diamond saw. The pulp chamber was exposed using a diamond bur in a highâspeed handpiece with pulpal remnants removed and canals instrumented using endodontic hand instruments. The chamber floor was restored using a resin core material with a twoâstep, selfâetch adhesive and photopolymerized with a visible lightâcuring unit to create a 2 mm endocrown preparation pulp chamber extension. One and two millimeter ferrule height groups were prepared using a diamond bur in a highâspeed handpiece following CAD/CAM guidelines. Completed preparation surface area was determined using a digital measuring microscope. Scanned preparations were restored with lithium disilicate restorations with a selfâadhesive resin luting agent. All manufacturer recommendations were followed. Specimens were stored at 37°C/98% humidity and tested to failure after 24 hours at a 45° angle to the tooth long axis using a universal testing machine. Failure load was converted to MPa using the available bonding surface area with mean data analyzed using KruskalâWallis/Dunn ( p = 0.05). Results Calculated failure stress found no difference in failure resistance among the three groups; however, failure load results identified that the endocrown preparations without ferrule had significantly lower fracture load resistance. Failure mode analysis identified that all preparations demonstrated a high number of catastrophic failures. Conclusions Under the conditions of this study, ferruleâcontaining endocrown preparations demonstrated significantly greater failure loads than standard endocrown restorations; however, calculated failure stress based on available surface area for adhesive bonding found no difference between the groups. Lower instances of catastrophic failure were observed with the endocrown preparations containing 1 mm of preparation ferrule design; however, regardless of the presence of ferrule, this study found that all endocrown restorations suffered a high proportion of catastrophic failures but at loads greater than reported under normal masticatory function.
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
Section titled âReferencesâ- 1995 - Fabrication of a metalâfree ceramic restoration utilizing the monobloc technique