Clinical-Laboratory Study: Protein Composite Restoration of Partially Demineralized Enamel

Objectives: Study was designed to optimize the combination laboratory data and instrumentation into clinical study design to determine the restorative activity of hydroxyapatite protein composite (HPC, Nanit®active) formulated into silica fluoride toothpaste on partially, demineralized enamel. Methods: Flat bovine enamel was etched with 5% citric acid for 10 sec. and scanned with profilometer. Reference areas were covered with nail varnish. Two 3mm diam. cores were placed on each side of maxillary appliance of four study participants in the first leg of a 4 x 4 seven day cross-over study. The study started in the evening before retiring with a 30 sec. application of the study toothpaste. Each day breakfast and lunch were eaten with the appliance in place. After eating, the appliance with enamel core specimens was brushed with study pastes and then the participants brushed their own teeth. The dental appliance and participant's teeth were brushed with an ISO Oral-B soft bristle manual toothbrush. At the end of the study, the enamel cores were removed from the appliances, placed in epoxy mounts and scanned with the profilometer. For the second week, a new set of enamel cores were characterized in the laboratory and placed in the dental appliances. The toothpaste given to each participant was reversed. Results: At the end of each study period, there was an equal accumulation of material on the demineralized area 38.4(±18.6) and 37.8(±26.0)% for test and placebo specimens. The specimens were then sonicated for 1 hr. to yield 34.4(±16.9) and 17.3(±17.8)% for test and placebo pastes, respectively. Difference was statistically significant. Conclusions: Composite toothpaste with HPC produced a thicker, more stable restoration of the partially demineralized enamel surface. Placebo toothpaste produced a comparable but less stable surface accumulation on the etched enamel substrate. The laboratory-clinical model was cost-effective first step in oral concept assessment.