Tooth movement and dimensional change of denture base materials using two investment methods

Area of Science:

• Dental Prosthetics
• Materials Science in Dentistry

Background:

• Accurate denture fabrication is crucial for patient comfort and function.
• Traditional gypsum investment methods are well-established but may have limitations.
• Alternative investment materials, like silicone rubber, are being explored to improve denture processing.

Purpose of the Study:

• To evaluate and compare two methods for investing maxillary dentures: a silicone rubber and gypsum base technique versus a conventional all-gypsum technique.
• To assess the impact of each investment method on vertical opening, tooth movement, and dimensional accuracy.
• To compare the fit of relined dentures versus heat-cured dentures processed with each technique.

Main Methods:

• In vitro investigation comparing silicone investment with a standard all-gypsum technique for maxillary dentures.
• Measurement of vertical opening and horizontal tooth movement (lingual/buccal) in processed dentures.
• Comparison of residual impression weight and assessment of denture base fit.
• Development of a specialized device for accurate measurement of tooth movement.

Main Results:

• Silicone investment and all-gypsum techniques resulted in comparable vertical opening.
• A trend towards more lingual horizontal tooth movement was observed with the silicone investment technique.
• No significant difference in residual impression weight was found between silicone and gypsum investment methods.
• Relined denture bases demonstrated a more accurate fit compared to heat-cured dentures, irrespective of the investment material used.

Conclusions:

• Both silicone and all-gypsum investment methods are viable for maxillary denture processing, yielding similar vertical dimensions.
• The silicone investment technique may influence horizontal tooth positioning, warranting further investigation.
• Relining offers improved denture fit over conventional heat-curing, regardless of the investment material employed.
• A novel device enables simple and accurate measurement of tooth movement in processed dentures.