Evaluation of Three Hard Relining Materials in Complete Dentures

Purpose: The purpose of this study is to evaluate three hard relining materials after 3 and 6 months of use with mandibular complete dentures. The effect of hard relining materials on supporting tissues and patients' satisfaction will also be assessed.

Materials and Methods: 36 complete edentulous patients who already have maxillary dentures and complaining of instable mandibular dentures will be invited to participate in this study. Mandibular dentures will be relined randomly by one of three relining materials: two chairside relining materials (Tokuyama Rebase II Fast, Tokuyama Dental Co, Japan), and (Flexacryl Hard, Lang Co, USA) and one heat cured acrylic resin (Vertex, Dental technology Co, Holland).

The color stability of relining material, peeling, and the effect on supporting tissue will be assessed by two separate prosthodontists after 3 and 6 months of follow up. In addition, patients will be asked to grade there overall satisfaction on a Visual Analogue Scale (VAS) ranging from 0 to 100.

Relining denture is a process of resurfacing the tissue side of a denture to make it fit more accurately Direct relining of removable dentures with hard chair-side reline materials is suitable for improving the fit of the denture bases to the supporting tissues. Chairside reline materials are more convenient than those processed in a laboratory because the direct method is faster and does not cause clinically significant dimensional changes of the reline resin. However, when autopolymerized reline resins are used with a direct method, several problems can occur as burning sensation caused by monomers, an exothermic heat reaction and an unpleasant odor.

There are three types of hard relining chair-side materials: Dual-polymerized Visible light-polymerized as Triad DuaLine, Light Liner (Hard), Astron LC (Hard).Visible light-polymerized as Lightdon-U, Triad Hi-Flow Reline Material, Triad VLC Reline Material. Finally, autopolymerized as New Truline, Tokuyama Rebase II (Fast) , GC Reline. Other concerns related to direct reline materials include patient tolerance (taste, temperature, odor), color stability, durability and ease of handling and polishing.

Few studies evaluated the effect of disinfection solutions on relining materials properties as roughness and hardness. In one study, disinfectant solutions caused a decrease in hardness, whereas with roughness, the materials tested showed a statistically significant increase, except for Tokuyama. Depending on the examined relining materials, some materials have increased and the others have decreased surface roughness after immersion in disinfecting solutions or microwave disinfection.

All previous laboratory studies concentrated on the effects of disinfection on relining materials properties as roughness, hardness, color change. However, the clinical studies did not compare chemically cured and heat cured relining materials and their effects on supporting tissue. The aim of this study is to evaluate the clinical performance of two -chemically cured- and heat cured denture relining material after 3 and 6 months of use. In addition, the effect of hard relining materials on supporting tissues, and patients' satisfaction has not been evaluated yet.

Eligibility Criteria:
Inclusion Criteria:

* Age between 45-80 year,
* complete maxillary and lower dentures
* Mandibular dentures with poor retention

Exclusion Criteria:

* Patients with good stability of mandibular dentures.
* Partial maxillary edentulous patients