Composite restoration usage in dentistry is increasing. Because of this interest in the longevity and reliability of composite fillings also is increasing1. One problem that can occur with composite restorations is micro-leakage. This is when microgaps at the tooth-restoration interface allow fluids and bacteria into the restoration2. These gaps are formed when the material is polymerized and shrinks, which causes the material to pull away from the margins of the preporation2. Problems that can arise from micro-leakage are secondary carries, hypersensitivity, pulp stimulation, and marginal discoloration3. This is why dentists are trying to find ways to reduce micro-leakage of composite restorations.
There are many different areas that can be looked at in attempting to find ways to reduce micro-leakage of composite fillings.
In comparing micro-leakage of resin-modified glass-ionomers (RMGI), flowable composite liners, and no liners, it was found that by applying a RMGI liner before placing the composite decreased the extent of micro-leakage3. By doing this, the farthest the micro-leakage occurred was to the cervical wall, whereas with composite liners and no liners there was leakage to the cervical wall and into the axial wall3. The reason for the difference could be attributed to the bond between the glass ionomer and composite. This bond is weak and can be thought of as an unbounded wall, leading to less shrinkage stress to the bonds between composite and dentin3.
If desensitizers are used before adhesives this adds a new layer to the restoration and there could be a difference with marginal sealing. On enamel there is no effect with reducing or increasing micro-leakage however when desensitizers are used on dentin there is a difference depending on what adhesive system was used4. Shafiei and others showed that if using Optibond FL or Excite there is higher micro-leakage when using an oxalate desensitizer on dentin while One-Step Plus and Adper Scotchbond Multi-Purpose had no difference in micro-leakage. This difference could be caused by the pH difference in the adhesives when mixed with the oxalate desensitizer4.
Bleaching on composites bound to enamel has no effect on micro-leakage, while bleaching on composites to dentin have an increase in micro-leakage5. This could be caused by enamel and dentin having different chemical structures. Enamel is more mineralized then dentin, which could help protect the bonding of composite to tooth structure. When patients do want to bleach their teeth a protective resin could be placed over restorations to help prevent micro-leakage and once done the resin can be polished off5.
Self-adhesive Resin Cement
Using a self-adhesive resin allows the dentist to cut down on time for restorations by combining the self etch and priming steps (compared to total etch where they are separate steps). A study done on different self-adhesive resins by Al-Saleh...