Bonding effectiveness of adhesive luting agents to enamel and dentin.
OBJECTIVE
The bonding effectiveness of five adhesive luting agents to enamel and dentin using different application procedures was determined using a micro-tensile bond strength protocol (microTBS).


METHODS
Enamel/dentin surfaces of human third molars were flattened using a high-speed diamond bur. Composite resin blocks (Paradigm, 3M ESPE) were luted using either Linkmax (LM; GC), Nexus 2 (NX; Kerr), Panavia F (PN; Kuraray), RelyX Unicem (UN; 3M ESPE) or Variolink II (VL; Ivoclar-Vivadent), strictly following manufacturers' instructions. For some luting agents, modified application procedures were also tested, resulting in four other experimental groups: Prompt L-Pop+RelyX Unicem (PLP+UN; 3M ESPE), Scotchbond Etchant+RelyX Unicem (SE+UN; 3M ESPE), Optibond Solo Plus Activator+Nexus 2 (ACT+NX; Kerr) and K-Etchant gel+Panavia-F (KE+P; Kuraray). The experimental groups were classified according to the adhesive approach in self-adhesive (UN), etch-and-rinse (ACT+NX, NX, KE+P, SE+UN and VL when bonded to enamel) and self-etch adhesive luting agents (LM, PLP+UN, PN and VL when bonded to dentin). The specimens were stored for 24h in distilled water at 37 degrees C prior to microTBS testing. The Kruskal-Wallis test was used to determine pairwise statistical differences (p<0.05) in microTBS between the experimental groups.


RESULTS
When bonded to enamel, ACT+NX (15 MPa) and UN (19.6 MPa) scored significantly lower than VL (49.3 MPa), LM (49.2 MPa), PN (35.4 MPa) and SE+UN (35.2 MPa), while PLP+UN (23.5 MPa) showed a significantly lower microTBS than VL (49.3 MPa) and LM (49.2 MPa). No significant differences were noticed between VL (49.3 MPa), LM (49.2 MPa), NX (37.9 MPa), KE+PN (38.8 MPa), PN (35.4 MPa) and SE+UN (35.2 MPa). Regarding the bonding effectiveness to dentin, all luting agents bonded equally effectively (UN: 15.9 MPa; LM: 15.4 MPa; PN: 17.5 MPa; NX: 22.3 MPa), except VL (1.1 MPa), SE+UN (5.9 MPa) and ACT+NX (13.2 MPa). VL revealed an exceptionally high number of pre-testing failures, most likely due to a combined effect of not having cured the adhesive separately and an insufficiently light-cured luting agent.


CONCLUSIONS
Following a correct application procedure, the etch-and-rinse, self-etch and self-adhesive luting agents are equally effective in bonding to enamel and dentin. Several factors negatively influenced bond strength such as bonding RelyX Unicem to enamel without prior phosphoric acid etching; no separate light-curing of a light-polymerizable adhesive prior to cementation, use of a light-polymerizing adhesive converted into a dual-polymerizing adhesive, and use of a dual-cure luting agent with a low auto-polymerizable potential.
Hikita
K
K
Leuven BIOMAT Research Cluster, Department of Conservative Dentistry, School of Dentistry, Oral Pathology and Maxillo-Facial Surgery, Catholic University of Leuven, Kapucijnenvoer 7, 3000 Leuven, Belgium.
Van Meerbeek
B
B
De Munck
J
J
Ikeda
T
T
Van Landuyt
K
K
Maida
T
T
Lambrechts
P
P
Peumans
M
M
D000134:Acid Etching, Dental; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003738:Dental Cements / Q000737:chemistry*; D003743:Dental Enamel / Q000648:ultrastructure*; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D063065:Organophosphonates / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
D003188:Composite Resins; D003738:Dental Cements; D017220:Dentin-Bonding Agents; C470486:Linkmax; D008689:Methacrylates; C433206:Nexus; C500960:OptiBond Solo Plus Self-Etch; D063065:Organophosphonates; C438843:Panavia-Fluoro; D010756:Phosphoric Acids; C408584:Prompt L-Pop; C483701:Rely X Unicem; D019279:Resin Cements; C454540:Scotchbond etchant; C452079:paradigm MZ100; D014867:Water; C103502:Variolink; D015040:Zirconium; C030242:phosphoric acid