Abstract:
Provisional crowns may be used for many weeks during healing
of soft tissues, while other dental procedures are being
performed and whilst the permanent restorations are being
fabricated. The provisional occlusion they present serves
a diagnostic purpose for fine tuning biological and biomechanical
requirements. They need to be strong enough to
withstand masticatory forces during this time, as it is costly,
inconvenient and time consuming to repair breakages. There
is no ideal provisional crown material, and new products appear
on the market regularly. Dentists need to know which
perform best in terms of strength, durability, ease of use,
aesthetics and cost to facilitate selection and purchase. This
study was undertaken to compare the compressive strengths
of seven different provisional crown materials, consisting of
three acrylic resins, three composites and one CAD/CAM
fabricated sample set. A custom-made stainless steel split
mould was constructed having a circular opening of 4mm in
diameter and 6mm in-depth and was used to prepare ten
specimens for each material. For the composites, the various
materials were syringed into the circular openings and compacted
using a ball burnisher. After five minutes, specimens
were removed. The heat cured acrylic resin specimens were
further processed in a pressure pot for five minutes. All samples
were stored in distilled water at 370C for 24 hours before
being tested. Test specimens were mounted into a jig on the
Instron machine and loaded under a compressive force until
they fractured or the compression limit was reached. The
forces applied were recorded and used for statistical analysis.
The results may help clinicians to select the most appropriate material for each clinical situation.
