Daijiro Meguro

Bonding durability of using self-etching primer with 4-META/ MMA-TBB resin cement to bond orthodontic brackets.

This study determines the bonding durability when a self-etching primer is used with Superbond C&B (a 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin) to bond orthodontic brackets to enamel. Thermocycling test was used to assess bonding durability. Metal brackets were bonded to the phosphoric acid-etched or Megabond self-etching primer-treated enamel surface of human premolars using Superbond C&B. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours or after 2000 or 5000 cycles of thermocycling between 5 degrees C and 55 degrees C. Data were analyzed using 2-way analysis of variance and Fishers protected least significant difference test for multiple comparisons. There was no significant difference in shear bond strength between phosphoric acid and Megabond self-etching primer treatment before the thermocycling test. After 2000 and 5000 thermal cycles, significant decreases in shear bond strength were observed with phosphoric acid etching. On the contrary, no significant differences in shear bond strength were observed after 2000 and 5000 thermal cycles with Megabond self-etching primer. The adhesive remnant indices were not significantly different between phosphoric acid etching and Megabond self-etching primer treatment either before or after thermal cycles. This study suggested that when used with Superbond C&B in bonding orthodontic brackets, Megabond self-etching primer is superior to phosphoric acid as an enamel preparation agent in providing durable bond strength.

In Vitro Antibacterial and Cytotoxicity Assessments of an Orthodontic Bonding Agent Containing Benzalkonium Chloride

OBJECTIVE To assess the antibacterial activity and cytotoxicity of an orthodontic bonding material containing an antibacterial agent. MATERIALS AND METHODS Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]) resin was mixed with benzalkonium chloride (BAC) to obtain final BAC concentrations of 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5.0% (wt/ wt). Antibacterial activity against Streptococcus mutans and Streptococcus sobrinus was evaluated by soaking the BAC-resin in distilled water at 37 degrees C for periods of 30, 90, and 180 days. Antibacterial activity of the BAC-resin was measured by the disk diffusion method, and the inhibition zone around each sample was measured and recorded. For evaluation of cytotoxicity, BAC-resin samples were put into cell culture inserts placed above human gingival cells and were incubated at 37 degrees C for 1, 3, and 6 days. Cytotoxicity was assessed with a tetrazolium bromide reduction assay. RESULTS The antibacterial activity of BAC-incorporated resin samples decreased significantly after immersion in water for 180 days, regardless of BAC concentration. The antibacterial activity of nonimmersed resin containing 0.25% or 1.75% BAC was comparable with that of 5.0% BAC-resin immersed for 180 days. In cytotoxicity tests, most cells died when exposed to resins containing 1.75%, 2.5%, and 5% BAC. No difference was observed between resins containing 0.25% and 0.75% BAC at 1, 3, and 6 days of culture. CONCLUSIONS The addition of BAC to 4-META/MMA-TBB resin confers an antibacterial effect even after immersion in water, and 4-META/MMA-TBB resin containing 0.25% to 0.75% BAC has no significant cytotoxic effect.

Shear Bond Strength of Calcium Phosphate Ceramic Brackets to Human Enamel

The aim of this study was to examine the shear bond strength between Hyaline brackets, a new type of calcium phosphate ceramic bracket, and human enamel using various types of adhesive resin and to investigate the effectiveness of a silane-coupling agent to bond Hyaline to human enamel. Kurasper F, Light Bond, Super Bond C&B, and Transbond XT were used as adhesive resins, and Porcelain Liner M was used as the silane-coupling agent. The Hyaline bracket was bonded to human enamel using one of the above adhesive resins according to the manufacturers instructions. After applying the Porcelain Liner M to Hyaline, the Hyaline bracket was also bonded to enamel using one of the above adhesive resins according to the manufacturers instructions. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. Three types of adhesive resin, Kurasper F, Light Bond, and Super Bond C&B, produced clinically acceptable shear bond strength with and without Porcelain Liner M. Transbond XT produced significantly lower bond strength to enamel with or without Porcelain Liner M (P < .05). The application of Porcelain Liner M was not useful for improving the bond strength of Hyaline to enamel. The adhesive remnant indices were not significantly different among four adhesive resins. In conclusion, adhesive resins such as Kurasper F, Light bond, and Super Bond C&B are useful for bonding esthetic Hyaline brackets to human enamel.

Antibacterial activity and shear bond strength of 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin containing an antibacterial agent.

OBJECTIVE To produce an antibacterial adhesive for orthodontic bonding without compromising the mechanical property. MATERIALS AND METHODS We added benzalkonium chloride (BAC) to the Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]), a resin that exhibits a strong bonding strength between enamel and bracket. BAC concentrations in the BAC composites were 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5% (wt/wt). Antibacterial activity of the BAC composite was measured by the disk diffusion method. BAC-composite discs were placed on the surface of the agar inoculated with Streptococcus mutans and Streptococcus sobrinus, and the plates were incubated at 37 degrees C. After 48 hours of incubation, the inhibition zone around each sample was measured and recorded. The BAC-modified composite was used to bond metal brackets to the phosphoric acid-etched enamel surface of human premolars. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. RESULTS The BAC-composite samples showed significant (P < .0001) antibacterial activity compared with the control. Measurable zones of bacterial inhibition increased as the BAC content in test samples increased. The shear bond strength declined with the increase in BAC concentration in the composite. A significant difference was found between the control composite and composites containing 1.25%, 1.75%, 2.5%, and 5% BAC (P < .05). No significant difference was found between the control composite and composites containing 0.25% and 0.75% BAC. However, shear bond strengths of the modified composites ranged from 10.12 MPa to 20.94 MPa. CONCLUSIONS These results confirmed that BAC-modified 4-META/MMA-TBB resin has a possibility for clinical application as an orthodontic bonding adhesive.

Efficacy of using orthodontic adhesive resin in bonding and debonding characteristics of a calcium phosphate ceramic bracket

Abstract The aim of this study was to examine the shear bond strength between a new type of calcium phosphate ceramic bracket and human enamel using various types of adhesive resins after thermal cycling tests. Kurasper F, Light Bond, Super Bond C&B and Transbond XT were used as adhesive resins. A new Hyaline II bracket was bonded to human enamel using one of the above adhesive resins according to the manufacturers instructions. Shear bond strengths were measured after immersion in water at 37 °C for 24 h, or after 2000 or 5000 cycles of thermal cycling between 5 °C and 55 °C. The Knoop hardness number (KHN) of Hyaline II and human enamel were measured. Significant differences in shear bond strength existed between Super Bond C&B and Transbond XT before thermal cycling. Four different adhesive resins produced significant differences in shear bond strength after thermal cycling compared with bond strength before thermal cycling. Four adhesive resins provided the clear formation of resin tags. The adhesive remnant indices were not significantly different among four adhesive resins. There are no significant difference in KHN at Hyaline II and human enamel. In conclusion, Hyaline II has an advantage for reducing the risk of enamel fracture or enamel crack without the loss of appropriate bond strength.