Fluoride-releasing Dentinal Bonding Agent and Secondary in vitro Root Surface Caries

Objective: This laboratory study evaluated the effects of a fluoride-releasing dentinal bonding agent (DentinBloc) on secondary in vitro caries formation in root surfaces. Methods: Cavity preparations were performed in both sound mesial and distal root surfaces in a total of 15 extracted permanent human teeth. The cavities were restored as follows: Group 1 (SMP): Scotchbond Multi-Purpose and Z250 composite resin; Group 2 (DB-1): Acid-Etch, Rinse, Slightly Air-Dried, DentinBloc adhesive, Slightly Rinsed, Slightly Air-Dried, Scotchbond Multi-Purpose, Z250 composite resin; Group 3 (DB-2): Acid-Etch, Rinse, Slightly Dried, DentinBloc adhesive, Slightly Air-Dried, Scotchbond Multi-Purpose, Z250 composite resin. In vitro secondary caries were formed using a modified ten Cate solution. After lesion formation (7 day exposure period), longitudinal sections (5 per specimen) were obtained and examined while imbibed in water with polarized light microscopy. Lesion depth and wall lesion frequency were determined (25 sections/group, 100 caries-risk sites/group) and compared statistically (ANOVA, DMR). Results: Mean primary (outer) lesion depths were: 195um SMP*; 109um DB-1; and 116um DB-2 (*p<0.05). Mean lesion areas were: 97x10³ um² SMP*; 54.6x10³ um² DB-1; and 58.1x10³ um² DB-2 (*p<0.05). Wall lesion frequencies were: 30% SMP*; 22% DB-1; and 17% DB2 (*p<0.05). Conclusions: The fluoride-releasing agent (DentinBloc adhesive) provided additional protection against secondary in vitro caries in root surfaces adjacent to composite resin restorations, as well as along the interface between the resin and prepared root surface cavosurface (p<0.05). Alteration in rinsing and air-drying following dentinal adhesive placement did not affect in vitro secondary caries formation (p>0.05).