Acid Etching of Titanium for Bonding with Veneering Composite Resins

Abstract

INTRODUCTIONCommercially pure titanium（cpTi）and its alloys are frequently used for dental prosthetic devices 1） . When they are used to restore anterior teeth, titanium prostheses are generally covered with an esthetic material, such as a composite resin. To obtain good retention between the metal core and resin, retention beads are generally cast on the metal surface to promote mechanical retention -and this form of mechanical retention has the highest survival rate in clinical prostheses 2） . However, a non-mechanical retention method for the metal core is preferred to minimize the removal of sound enamel and dentin when preparing the tooth for cementation. Furthermore, a machining method -versus casting -was developed recently for the fabrication of titanium prostheses. Consequently, there arose an intense, two-pronged effort to develop a new adhesive system that would deliver improved adhesion with the titanium substrate produced by machining. The two key approaches were: focus on the development of adhesion-promoting monomers 3,4） , as well as explore pretreatment methods that would modify the substrate surface for optimal adhesion 5-7） . In the quest for an optimal pretreatment method for titanium, the authors have examined supercritical water 8） and alkaline 9） treatments. Both treatments significantly increased the bond strength of treated titanium to veneering resins.Essentially, these treatments depend on the roughened, tough oxide texture on the surface of treated titanium. However, it was reported 10） that after thermal cycling, the bonding strength decreased remarkably such that the bonding durability was no longer considered sufficient for long-term restorations. On the other hand, the authors have also reported that etching in concentrated H 2 SO 4 at 40 to 90 ℃ produced a highly roughened surface on cpTi and Ti-6Al-4V alloy 11,12） . Therefore, acid etching might be an alternative, effective pretreatment for titanium for the purpose of promoting better bonding to veneering resins.However, acid etching of Ti-6Al-4V alloy provides only adequate dry strength with reportedly poor durability 13）. In this study, therefore, we examined whether etching in concentrated acid enhanced the bond strength durability between cpTi and veneering resin. To this end, we measured the bond strength of acid-etched cpTi to veneering resins before and after thermal cycling, and then discussed the possibility of using acid etching as a pretreatment method for dental restoratives comprising titanium substrate and veneering composite resins. MATERIALS AND METHODS Substrate metalCpTi plates （KS-50, JIS type 2, Kobelco, Kobe, Japan） were used as the substrate. Metal plates measuring 20 × 15 × 1 mm were sandblasted （Hi-Blaster II, Shofu, Kyoto, Japan）with alumina powder（70μm） , cleaned in distilled water supersonically, and dried in air at room temperature. Acid etchingCpTi plates were etched using 11 treatments involving differences in the acid solution （18％ HCl, 43％ H 3 PO 4 , and 4.8 and 48％ H 2 SO 4 ） , soak...

Effect of Air Abrasion and Different Silicoating Techniques on the Bond Strength of Particulate Filler Composite to Titanium

“…However, one of the problems associated with titanium metal-composite restorations is insufficient ability to bond resin to titanium metal castings. The deficient bonding of indirect composites to the metallic alloys could promote the formation of marginal gaps and causing weak bond strength [2,3,6,8,9]. Like other metal alloys, use of titanium alloy for fixed partial denture requires a strong and stable bond between metal and esthetic veneering material (porcelain or composite resin) or metal and resin cement [11,13].…”

“…For this reason, particulate filler composite resin materials used on titanium castings as an alternative to porcelain fused to metal restorations for esthetic anterior/posterior restorations [9][10][11][12]. Indirect lightcured composite resins have been extensively used in tooth restoration because they can provide acceptable aesthetics, wear resistance similar to tooth structure, and are easy to manipulate in the laboratory and to repair [3,8,9]. However, one of the problems associated with titanium metal-composite restorations is insufficient ability to bond resin to titanium metal castings.…”

“…Although various metal alloy can be used to fabricate fixed partial dentures, titanium presents several advantages as a prosthetic material, such as excellent biocompatibility, good mechanical properties, high corrosion resistance, low density and low cost compared to noble metals [2][3][4][5][6][7][8][9][10][11]. However, problems with porcelain bonding have been reported when titanium is used in metal-ceramic restorations as thick and non-adherent layers of titanium oxide are formed.…”

“…The development of new processing methods-such as lost-wax casting, computer-aided machining and electric discharge machining-has allowed the use of pure titanium and its alloys for dental implants, surgical splints, stents and fasteners, partial denture frameworks, fixed partial dentures and root posts [1][2][3][4][5][6][7][8][9]. Although various metal alloy can be used to fabricate fixed partial dentures, titanium presents several advantages as a prosthetic material, such as excellent biocompatibility, good mechanical properties, high corrosion resistance, low density and low cost compared to noble metals [2][3][4][5][6][7][8][9][10][11].…”

“…Macro-(mesh, beads, rough surface with particles) or micro-mechanical treatments (air-abrasion with alumina particles, electrolytic etching, porous metal coating, and acid etching), chemical treatments (4-META composites, phosphate-based composites) and adhesive layer application (tin plating, titanate coupler, silane coupling, carboxylic monomers, a phosphate monomer) were the only mechanisms for bonding composite materials to metallic substrates [2,3,[6][7][8][9]14]. …”