Design of New Phosphonic Acid Monomers for Dental Adhesives-Synthesis of (Meth)acryloxyalkyl 3-phosphonopropionates and Evaluation of their Adhesion-promoting Functions

Abstract

The aims of this study were to synthesize new phosphonic acid monomers, and to examine their bonding performance. Four kinds of newly designed phosphonic acid monomers were synthesized, and seven experimental composite-type adhesive resins comprising the synthesized monomers(3 wt％) , with BPO/DEPT/BPBA initiator were prepared. Tensile bond strengths of the adhesive resins to enamel and metal were measured with a universal testing machine at a crosshead speed of 1.0 mm/ min. The synthesized adhesive monomers were light yellow viscous liquids with 32.5％-49.3％ yields, and identified by 1 H NMR, IR and elemental analysis to be(meth) acryloxyalkyl 3-phosphonopropionates［R-P (＝O) (OH) 2 ］ (5-MPPP, 6-MHPP, 6-AHPP, 10-MDPP). It was found that the newly developed phosphonic acid monomers with BPO/DEPT/BPBA initiator attained strong adhesion to both unetched, ground enamel and sandblasted Ni-Cr alloy with good durability. They exhibited significantly higher bond strengths than conventional phosphorous-containing monomers such as MEPP and VBPA (p ＜0.01). These findings indicate that the experimental phosphonic acid monomer-containing adhesive resins have potential prosthodontic and orthodontic applications, especially as self-etching, non-rinsing orthodontic adhesive resins.

Design of a new, multi-purpose, light-curing adhesive comprising a silane coupling agent, acidic adhesive monomers and dithiooctanoate monomers for bonding to varied metal and dental ceramic materials

“…Acidic adhesive monomers and sulfur-containing monomers are classified as two different categories of adhesive monomers: the former contains acidic groups such as carboxylic acid, phosphoric acid or phosphonic acid, while the latter contains a sulfur atom in their structures. For acidic adhesive monomers, they play a key role in the action of recently developed self-etching primers and adhesives in that they can interact chemically as ligand monomers not only with hydroxyapatite in dental hard tissues 4) , but also with metal oxides on the surfaces of non-precious metals 5) and with alumina-based and zirconia-based ceramics 6) . For sulfur-containing monomers, they are able to chemically interact with metal atoms on the surfaces of precious metals [7][8][9] .…”

“…However, multi-purpose, light-curing adhesives or bonding resins which contain the same ingredients listed above are rarely reportedlet alone single-bottle adhesives. In our previous studies, acidic adhesive monomers bearing carboxylic acid or its anhydride group 15,16) and phosphonic acid group 5,17) were developed. Besides, eight kinds of acryloyloxyalkyl and methacryloyloxyalkyl 6,8-dithiooctanoates (dithiooctanoate monomers) as novel sulfur-containing monomers were also developed 18) .…”

Design of a metal primer containing a dithiooctanoate monomer and a phosphonic acid monomer for bonding of prosthetic light-curing resin composite to gold, dental precious and non-precious metal alloys

“…Acidic adhesive monomers and sulfur-containing monomers are classified as two different categories of adhesive monomers by virtue of their adhesionpromoting groups. An outstanding characteristic of advanced acidic adhesive monomers is their ability to chemically interact with metal oxides on the surfaces of non-precious metals 19) . As for advanced sulfur-containing adhesive monomers -which contain a sulfur atom in their adhesion-promoting groups, they are able to chemically interact with metal atoms on the surfaces of precious metals [20][21][22][23] .…”

“…In the course of our development of a multi-purpose adhesive, several acidic adhesive monomers bearing carboxylic acid (-COOH) or its anhydride group 26) and phosphonic acid group 19,27) were previously developed. Besides, eight kinds of acryloyloxyalkyl and methacryloyloxyalkyl 6,8-dithiooctanoates (dithiooctanoate monomers) as novel sulfur-containing monomers were also developed 28) .…”

“…For phosphonic acid monomers ( Fig. 1(b)) -namely, 6-MHPA and 6-MHPP, they were synthesized via an esterification reaction between 6-hydroxyhexyl methacrylate and phosphonoacetic acid or 2-carboxyethylphosphonic acid as previously described 19,27) .…”