Remineralization of Dentin Lesions from Whisker-Reinforced, Resin-Based Composites

OBJECTIVE:  Recent research to develop materials for improved treatment and prevention of dental caries in Atraumatic Restorative Treatments (ART) has resulted in a number of whisker-reinforced, resin-based composites that release calcium, phosphate, and fluoride ions at concentrations necessary for the remineralization of targeted tissues.  This in-vitro study explored the remineralization of artificial human dentin lesions from five such composites.  METHODS:  One oval cavity was drilled into the occlusal dentin surface of thirty-five extracted caries-free human molars.  All teeth were coated with acid-resistant varnish except the cavity, and exposed to demineralizing solution (pH=4.3, 37ºC, 48h).  The cavity was filled with one of the five experimental composites, the fluoride-free composite TPH, or a fluoride-releasing GIC.  The restoration was light-cured (2min), and incubated (37°C, 20min).  The tooth was sliced into 180µm sections.  After taking contact microradiographs and implementing digital image analysis to determine the “mineral-loss-before”, each section was sandwiched between a layer of parafilm and a plastic cover slip, and then wrapped with parafilm exposing only the restoration edge.  Each section was incubated in 25mL of artificial saliva solution (pH=7.0, 37°C, 4wks).  Contact microradiographs of each section were retaken, and the mineral loss under the restorations after treatment was determined.  The % remineralization was calculated from (1- “mineral-loss-after” / “mineral-loss-before”) x 100.  RESULTS:  The % remineralization (± Std.Dev.), after 4wks, for all treatment groups (n=5) are:  B1^a =30±8, B3^a =28±7, B4^a =28±8, B6^a =32±11, U3^a =33±8, TPH^b =13±3, GIC^a =32±5.  Holm-Sidak multiple comparison procedures indicated that the five experimental composites and GIC control were significantly different from TPH (p<0.05).  There was no significant difference between the five experimental composites and GIC; or among the five experimental composites (p>0.05).  CONCLUSION:  In addition to GIC, all five experimental composites developed for ART remineralized human dentin lesions.  Support: ADAF, NIST, and NIDCR Grant DE13298.