Effect of resin/fluoride and holmium:YAG laser irradiation on the resistance to the formation of caries-like lesions.
OBJECTIVE
This study compared the effects of a combination of a topical application of resin/NaF mixture and holmium-doped yttrium aluminum garnet (HO:YAG) laser energy with untreated control sites for their resistance to acid destruction/mechanical challenges of root surfaces adjacent to restorative margins.


METHODS
Forty-eight extracted human teeth were prepared for restorations with coronal margins in enamel and the apical margins on root surfaces. Four types of restorative materials were used. One half of the restorative/root surface margins were treated with an application of nonfilled resin/fluoride mixture and holmium-doped yttrium aluminum garnet laser irradiation; the remaining portion served as the untreated control for each tooth. Acid (10% formic) and mechanical (air sandblaster) challenges were used to test the effects of these treated sites to their controls and to other types of restorative/root surface margins. The depth of root surface loss within 0 to 2 mm apical from the restorative margins was measured and evaluated after 24, 48, and 72 hours of acid exposures.


RESULTS
The measurements of tooth loss for the 24- and 48-hour acid-exposure cycles were subjected to statistical analysis (ANOVA) using a paired t test for the variables. The variables, depth of tooth surface loss for the control sites was compared with the depth of loss of the treated sites on opposing sides of each tooth. The depth of tooth surface loss for the control sites had an average mean of 0.35 (0.25) mm for the 24-hour acid exposures, with the opposing treated sides having a mean of 0.053 (0.05) mm (significant at the 0.05 level). The 48-hour acid-exposure results showed significant increased tooth loss for the control sites, but minimum additional loss on the treated sites. The control sites showed an average mean of 1.16 (0.24) mm and a mean of 0.095 (0.103) mm for the treated areas, significant at the 0.05 level. No measurements were made for the 72-hour cycle groups of composite and amalgam alloy restorations because of the loss of most of the filling materials in the control sites. The control groups of crowns showed an average mean loss of 2.06 (0.37) mm with only 0.20 (0.19) mm surface loss for the treated sites. The paired t test for variables indicated no significant differences of tooth surface loss between various types of restorative margins used in this study.


CONCLUSIONS
HO:YAG laser energy irradiation after application of resin/NaF to restorative margins and adjacent areas showed a significant increased resistance to acid/mechanical destruction on cementum-dentin root surfaces. The integrity of the restorative/dentin margins were maintained after extended exposures to formic acid and mechanical challenges.
Holt
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RA
Oklahoma University, College of Dentistry, Oklahoma City 73190, USA.
Nordquist
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D003188:Composite Resins / Q000627:therapeutic use*; D003733:Dental Caries Susceptibility / Q000187:drug effects* / Q000528:radiation effects*; D003793:Dental Restoration, Permanent / Q000379:methods; D004338:Drug Combinations; D005069:Evaluation Studies as Topic; D005561:Formates / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D053685:Laser Therapy; D017213:Root Caries / Q000517:prevention & control; D012969:Sodium Fluoride / Q000627:therapeutic use*; D013997:Time Factors
D003188:Composite Resins; D004338:Drug Combinations; D005561:Formates; C030544:formic acid; D012969:Sodium Fluoride