Two years ago, I had the chance to hear Dr. John Burgess speak at The University of Texas Dental School. Dr. Burgess is an amazing clinician and lecturer. His knowledge of materials is ridiculous.
He re-emphasized the importance of the technique sensitivity of bonding procedures. One step that is often overlooked is phosphoric acid etching. Dr. Burgess suggested that after acid etch is placed, the metal tip of the applicator should be used to agitate the etch. Upon agitation, small bubbles will become visible in the etch. This means that the air trapped inside the prep is being pushed out and etch is filling the entire preparation, giving us a more even and tubule-penetrating etch.
I had never seen a study that reinforced this until this morning. This study comes out of the ortho literature...maybe thats why I had never seen it.
"The effects of differing acid concentrations, techniques and etch time on the etch pattern of enamel of erupted and unerupted human teeth examined using the scanning electron microscope." Oliver RG. Br J Orthod. 1988 Feb;15(1):45-9.
In this study, it showed that both concentration and agitation of etch are important factors in producing the roughened surface needed for bonding.
Dr. Burgess suggested that agitation of etch alone can increase bond strength by 20% however no data was given to support the claim. I am not sure if it can increase bond that much, however I do feel that agitation of etch is an important step in producing a good bond.
He re-emphasized the importance of the technique sensitivity of bonding procedures. One step that is often overlooked is phosphoric acid etching. Dr. Burgess suggested that after acid etch is placed, the metal tip of the applicator should be used to agitate the etch. Upon agitation, small bubbles will become visible in the etch. This means that the air trapped inside the prep is being pushed out and etch is filling the entire preparation, giving us a more even and tubule-penetrating etch.
I had never seen a study that reinforced this until this morning. This study comes out of the ortho literature...maybe thats why I had never seen it.
"The effects of differing acid concentrations, techniques and etch time on the etch pattern of enamel of erupted and unerupted human teeth examined using the scanning electron microscope." Oliver RG. Br J Orthod. 1988 Feb;15(1):45-9.
In this study, it showed that both concentration and agitation of etch are important factors in producing the roughened surface needed for bonding.
Dr. Burgess suggested that agitation of etch alone can increase bond strength by 20% however no data was given to support the claim. I am not sure if it can increase bond that much, however I do feel that agitation of etch is an important step in producing a good bond.