Microtensile Bonding Strength of Antibacterial and Fluoride-Releasing Sealants to Enamel

<>Antibacterial fluoride-releasing sealants may have additional anticariogenic effect. There are concerns about the adhesion and retention of these sealants on enamel. Objective : to test enamel microtensile bonding strength (MTBS) of experimental and commercial antibacterial and fluoride-releasing sealants. Methods : Two experimental antibacterial fluoride-releasing sealants (Exp-1 and Exp-2) were formulated using synthesized antibacterial fluoride-releasing monomer and other dental monomers (BisGMA/EBPADMA/HDDMA/EGDMA) and fluoride-releasing filler (Caulk/Dentsply). Exp-2 also contains 15% NovaMin bioactive glass particles (GlaxoSmithKline). Two commercial fluoride-releasing sealants [FluroShield (FS) (Caulk/Dentsply), Clinpro (CP) (3M-ESPE)] and an antibacterial non-F-releasing sealant SeLECT Defense (E34) (Element 34 Technology) were also included. Twenty extracted molar teeth were divided into 5 groups (n=4), ground with 600-grit SiC papers to expose flat enamel. The specimens were etched with 37% phosphoric acid gel for 15 seconds, rinsed, and dried. The sealants were applied and light cured 20s. Filtek Supreme Plus composite (3M ESPE) was placed on cured sealant, cured for 40s, and built up incrementally to 4-5mm. The samples were stored in DI-water for 24h at 37◦C, then sectioned into bar specimens (1x1mm cross-section). For each group, 15 specimens were tested on microtensile tester for MTBS. The remaining 15 specimens were thermocycled 5-55◦C for 1000 cycles and then tested for MTBS. The data were analyzed using ANOVA and Tukey test. A paired t-test was used to compare the mean MTBS under different storage conditions.

 

Results : Table 1.� Microtensile Bonding Strength (Mean�SD)

Materials	MTBS, 24h (MPa)*	MTBS, 1000-Thermocycles (MPa)
FS	24.13�4.76A	25.62�4.32
Exp-2	24.60�3.83A	23.79�4.90
Exp-1	22.71�3.39A,B	21.99�3.75
CP	20.24�4.81A,B	22.53�5.61
E34	19.29�4.73B	22.97�5.20

*The groups with the same superscript latter have no significant difference (p>0.05). There is no significant difference among all groups after thermocycles and between 24h and thermocycles.

Conclusion : the experimental and commercial antibacterial and fluoride-releasing sealants have similar bonding strengths to enamel (Supported by NIH/NIDCR grant 5R01DE019203-03).