FDA confirmed in Guidance for Industry: Gingivitis (2005) the correlation between Gingivitis and plaque mass and FDA considered in the monograph (21 CFR Part 356) testing of the antigingivitis / antiplaque effectiveness of drug products the Plaque Glycolysis and Regrowth Model (PGRM) to link plaque activity with gingivitis incidence.
Aim of this pilot study was to investigate plaque-growth and plaque activity inhibition by a resin-modified glass-ionomer luting-cement in comparison to enamel and dentin in a microcosm plaque-model.
Method:
Human saliva was used to grow plaque on bovine enamel, dentin and RelyXTM Luting Plus (3M ESPE) samples (n=6). Plaque growth was initiated via 1:4 mixture of human saliva and MCM-sucrose-culture media for 4 hr/37°C; the media was replenished for the next 22 hr/37°C. Plaque was collected and dried to determine plaque biomass and related to the exposed surface area of each specimen. In accordance to PGRM, lactic acid release was quantified in using ClinproTM Cario L-PopTM (3M ESPE).
Result:
An average plaque mass of 1.52±0.18 mg/cm² was found on RelyXTM Luting Plus which represents a statistically significant difference (p<0,05, Two-Sample T-Test) to the plaque mass found on enamel 3.77±0.83 mg/cm² or dentin 6.31±0.83 mg/cm². The difference in plaque accumulation between enamel and dentin was also statistically significant (p<0.05). Plaque grown on enamel (1.11mM/mg•cm²•h) and dentin (1.15mM/mg•cm²•h) did not possess statistically different lactic acid formation activities. Substantially less lactic acid formation was observed with plaque grown on RelyXTM Luting Plus 0.12mM/mg•cm²•h (statistically significant, p<0.05).
Conclusion: In comparison to enamel and dentin RelyXTM Luting Plus inhibits plaque accumulation and PGRM activity. Both indicate that the bioactivity of RelyXTM Luting Plus might contribute to prevent inflammatory processes of soft tissue such as gingivitis or peri-implantitis. Further investigations have been initiated to leverage understanding of this preventive effect of resin-modified glass ionomer luting-cements.