Review of methyl methacrylate (MMA)/tributylborane (TBB)-initiated resin adhesive to dentin

Effects of sodium copper- and sodium iron-chlorophyllin primers on resin bonding to dentin

This study evaluated the effects of two chlorophyll derivatives, sodium copper chlorophyllin (Cu-Chl) and sodium iron chlorophyllin (Fe-Chl), on the bond strength between a self-curing luting agent (4-META/MMA-TBB resin) and dentin. Five aqueous primers containing 35% 2-hydroxyethylmethacrylate with 0.007% Cu-Chl, 0.07% Cu-Chl, 0.007% Fe-Chl, 0.07% Fe-Chl, or neither Cu-Chl nor Fe-Chl (no-Chl) were prepared. The extracted human dentin surfaces were etched with 10% phosphoric acid (10PA), primed, and bonded to a resin block using the 4-META/MMA-TBB resin. A conventional etching agent (10-3) and 10PA without primer (PA/no-primer) were used as controls. The microtensile bond strength was determined after 48 h. The arithmetic medians for 20 stick specimens were calculated and statistically analyzed using a nonparametric Steel-Dwass test (α = 0.05). The maximum bond strength was achieved in the 0.007% Cu-Chl group, followed by those in the 0.07% Cu-Chl, 0.07% Fe-Chl, 10-3, 0.007% Fe-Chl, no-Chl, and PA/no-primer groups. No significant difference was observed between 0.007% Fe-Chl, 0.07% Fe-Chl, and 10-3. The bond strength to dentin etched with 10PA was influenced by the type and concentration of the chlorophyll derivatives applied. Cu-Chl rather than Fe-Chl should be useful as a component of surface treatment agents for bonding 4-META/MMA-TBB resin to dentin.

Effects of immersion in 4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin-activated liquid on microtensile bond strength of root canal dentin

Background/purpose

4-methacryloyloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin is used for indirect restorations. We aimed to evaluate effects of immersion in 4-META/MMA-TBB-activated liquid on the bond strength of root canal dentin.

Materials and methods

We used freshly extracted single-rooted human teeth. After decoronation, each root was vertically sectioned into halves; their dentin walls were polished and flattened. The control group underwent dentin treatment with Green Activator. The immersion group was treated with Green Activator and Teeth Primer and immersed in 4-META/MMA-TBB-activated liquid. After bonding the resin blocks with Super-Bond, microtensile bond strength (μTBS) tests were performed (n = 6), and fracture surfaces were analyzed. Before surface treatment, dentin was immersed in a sodium fluorescein solution for 3 h, and resin blocks were bonded with Super-Bond with rhodamine B as in the bond strength test. The bonded cross section was observed using confocal laser scanning microscopy (CLSM).

Results

μTBS was significantly higher in the immersion group than in the control group (61.5 [51.3-66.7] vs. 33.0 [20.4-57.8] MPa; P < 0.05). Fracture mode analysis showed that, compared with the control group, the immersion group had a significantly lower rate of adhesive failure at the dentin interface and a significantly higher rate of cohesive failure in Super-Bond (P < 0.01). CLSM showed a water droplet-like accumulation of fluorescein dye above the hybrid layer in the control group, not in the immersion group.

Conclusion

Immersion in a 4-META/MMA-TBB-activated liquid inhibited water exudation from the root canal dentin and improved the bond strength.

An up to 43-year longitudinal study of fixed prosthetic restorations retained with 4-META/MMA-TBB resin cement or zinc phosphate cement

STATEMENT OF PROBLEM

Adhesive resin cement has been the preferred choice for the placement of prosthetic restorations, but evidence-based studies supporting this selection are sparse.

PURPOSE

The purpose of this study was to test the hypothesis that restoration placement with the adhesive 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tributylborane (4-META/MMA-TBB) resin cement is associated with better longevity of teeth than zinc phosphate cement up to 43 years.

MATERIALS AND METHODS

Study participants were individuals who had been visiting the clinic regularly for more than 20 years from their first visit between November 1970 and April 1985. The vital teeth with prosthetic restorations (N=454), including cast inlays, onlays, crowns, and fixed partial dentures, of 53 patients were assessed from dental charts and radiographs. Most of the bonding surfaces were precious metal alloy, excluding 4 restorations cemented with zinc phosphate and 6 ceramic crowns cemented with 4-META/MMA-TBB resin cement. The Kaplan-Meier method and log-rank test (α=.05) were used to compare longevity between the 2 materials. Chi-squared tests (α=.001) were also used to examine the occurrence rates of events such as secondary caries, endodontic treatment, and the dislodgement of restorations affecting the longevity of the 2 cements.

RESULTS

Clinical review examination demonstrated that 55.4% of teeth retained with 4-META/MMA-TBB resin cement had been in service for 30 years compared with 43.5% of those retained with zinc phosphate cement, with a significant difference (P=.006). 4-META/MMA-TBB resin cement also demonstrated lower event occurrence rates than zinc phosphate cement for 3 assessed types of events (P<.001).

CONCLUSIONS

Within the limitations of this study, 4-META/MMA-TBB resin adhesive cement demonstrated a higher survival rate than conventional zinc phosphate cement in service for 30 years with a lower occurrence of critical events.

Addition of metal chlorides to a HOCl conditioner can enhance bond strength to smear layer deproteinized dentin

OBJECTIVES

To evaluate the effect of smear layer deproteinization using hypochlorous acid (HOCl) with/without metal chlorides (SrCl₂ and ZnCl₂) on the microtensile bond strength (µTBS) of two simplified adhesives to dentin.

METHODS

Human dentin surfaces with a standardized smear layer were pretreated using a 105 ppm HOCl solution with/without SrCl₂ (0.05 M, 0.1 M, 0.2 M, 0.4 M) or ZnCl₂ (0.05 M, 0.1 M, 0.2 M) for 5 s, 15 s, or 30 s. After the deproteinizing solution was washed out with water for 5 s, 15 s, or 30 s, pretreated surfaces were bonded with one-step self-etch adhesive Bond Force II or universal adhesive Clearfil Universal Bond Quick, and µTBS was measured after 24 h. Additionally, the deproteinizing effects of HOCl solutions with/without the metal chlorides were compared by measuring changes in the amide:phosphate ratio using attenuated total reflection Fourier transform infrared spectroscopy. Statistical analysis was performed using multifactor ANOVA, Tukey's post hoc tests and t-tests (p < 0.05).

RESULTS

Pretreatment with pure HOCl for 15 s and 30 s significantly decreased the amide:phosphate ratio (p < 0.05), indicating effective deproteinization, but the µTBS of both adhesives increased significantly only if HOCl was washed out for 30 s (p < 0.05). Increasing the concentrations of metal chlorides enabled shortening of the wash-out time down to 5 s while maintaining the improved µTBS (p < 0.05). The deproteinizing effect of HOCl was not significantly altered by the addition of metal chlorides (p > 0.05).

SIGNIFICANCE

The effectiveness of smear layer deproteinization using HOCl can be improved by the addition of metal chlorides, as their increasing concentration allowed to shorten the wash-out time from 30 s down to 5 s.

Coronal and apical leakage among five endodontic sealers

PURPOSE

The aim of this study was to use dye penetration to measure apical and coronal leakage simultaneously in single-canal teeth that had been treated endodontically using a single-cone obturation technique.

METHODS

One hundred single-canal, extracted human teeth were cleaned and shaped with ProTaper NEXT rotary files to size-X5 (50/.06), then randomly assigned to five sealer groups for single-cone gutta-percha obturation. The teeth were soaked in 0.6% rhodamine B at 37°C for seven days, then the roots were ground mesiodistally and the maximum apical and coronal dye penetration was measured. Differences in leakage among the sealer groups were examined using the Kruskal-Wallis test. Pairwise comparisons were made using the Mann-Whitney test with Bonferroni correction.

RESULTS

The mean values (mm) of dye penetration for AH Plus, Pulp Canal Sealer, NeoSEALER Flo, EndoSequence BC, and Super-Bond RC Sealer were 0.200, 0.300, 0.675, 0.850, and 0.900 apically, whereas 1.675, 2.075, 4.800, 6.500, and 4.125 coronally. Pairwise comparisons showed significant apical differences between AH Plus/Super-Bond RC Sealer (P = 0.047) and significant coronal differences between AH Plus/NeoSEALER Flo (P = 0.001), AH Plus/EndoSequence BC (P < 0.01), AH Plus/Super-Bond RC Sealer (P < 0.01), Pulp Canal Sealer/NeoSEALER Flo (P = 0.010), Pulp Canal Sealer/EndoSequence BC (P < 0.01), and Pulp Canal Sealer/Super-Bond RC Sealer (P < 0.01).

CONCLUSION

Coronal leakage was worse than apical leakage for all sealers. AH Plus exhibited the least leakage apically and coronally; Super-Bond RC Sealer showed the most leakage apically, and EndoSequence BC showed the most leakage coronally.

Development of a novel direct dental pulp-capping material using 4-META/MMA-TBB resin with nano hydroxyapatite

In the case of dental pulp exposure, direct pulp capping is often performed to preserve vital dental pulp tissue. Numerous studies regarding the development of direct pulp-capping materials have been conducted, but materials with an appropriate sealing ability, which induce dense reparative dentin formation, have not been developed. Although nano hydroxyapatite (naHAp) is a bone-filling material with bioactivity and biocompatibility, the inductive effects of naHAp on reparative dentin formation remain unclear. In the present study, the effects of dental adhesive material 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate tri-n-butylborane [4-META/MMA-TBB or Super-bond (SB)], which included 10%, 30%, and 50% naHAp (naHAp/SB) on odontoblastic differentiation of dental pulp stem cells (DPSCs) and reparative dentin formation were investigated. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer analysis were performed to verify the existence of naHAp particles on the surface of naHAp/SB discs. The tensile adhesive strength of naHAp/SB was measured using a universal testing machine. As a result, 10% naHAp/SB and 30% naHAp/SB showed almost the same tensile adhesive strength as SB but 50% naHAp/SB showed significantly lower than the other experimental group. WST-1 proliferation assay and SEM analysis revealed that naHAp/SB did not affect the proliferation of DPSCs. Calcium release assay, quantitative RT-PCR, and western blotting analysis demonstrated that naHAp/SB did not release calcium ion but 30% naHAp/SB increased the expression of calcium-sensing receptor (CaSR) in DPSCs. Additionally, quantitative RT-PCR, western blotting analysis, Alizarin Red S- and von Kossa staining revealed that 30% naHAp/SB induced odontoblastic differentiation of DPSCs, which was inhibited by a MEK/ERK inhibitor and CaSR antagonist. Furthermore, 30% naHAp/SB promoted dense reparative dentin formation in an experimentally-formed rat dental pulp exposure model. These findings suggest that 30% naHAp/SB can be used as an ideal direct pulp capping material.

Evaluation of the cytocompatibility of methacrylate resin-based root canal sealers with osteoblast-like cells

This study compared the cytocompatibilities of three methacrylate resin-based root canal sealers [MetaSEAL Soft (MSS), Hybrid Root SEAL (HRS), and Superbond Sealer (SBS)] in either freshly mixed or set conditions using the Kusa A1 osteoblastic cell line. The three sealers and an epoxy resin-based sealer (AH Plus; AHP) were extracted in culture medium; cell growth and osteogenic properties were analyzed. Cell adhesion on set sealers was analyzed with scanning electron microscopy. The respective extents of cell growth were as follows in freshly mixed and set sealer extracts: SBS>MSS>AHP>HRS and SBS=AHP>MSS>HRS. Light irradiation of MSS and HRS increased the cell growth of set sealer extracts. Set SBS, MSS, and AHP did not alter expression of osteogenic genes or formation of mineralized nodules. Attached cells were observed only on SBS. In conclusion, the four sealers exhibited varying degrees of compatibility to osteoblasts; SBS and HRS were the most and least compatible, respectively.

Study on the performance of methyl methacrylate polymerization: Comparison of partially oxidized tri-n-butylborane and benzoyl peroxide with aromatic tertiary amines

In this study, we examined the polymerization performance of methyl methacrylate (MMA) initiated with partially oxidized tri-nbutylborane (TBBO) compared to that initiated with benzoyl peroxide and aromatic tertiary amine (BPO/amine) system. In the bulk polymerization of MMA at 37°C, conversion initiated with TBBO after 3 h was nearly quantitative, whereas the conversion with the BPO/amine system was low (~20%). The number-averaged and weight-averaged molecular weight of the TBBO-initiated polymer was more than twice as high as that of the BPO/amine-initiated polymer. Electron spin resonance (ESR) analysis of MMA polymerization indicated that the TBBO-initiated system maintained its radical intensities for a longer period than the BPO/amine-initiated system. Furthermore, the radical fragments in the TBBO-initiated PMMA after 72 h were still active as a polymerization initiator for MMA. These findings suggest that the polymerization mechanism of MMA initiated by TBBO functions as a living-like polymerization initiator.

Long-term marginal adaptation and nanoleakage of class V cavity restored with organic filler filled 4-META/MMA-TBB resin

The current restorative materials used for cervical lesions restoration still need to be improved. A low E-modulus restorative material Bondfill SB (group BF) is developed. This study was to evaluate marginal adaptation and nanoleakage expression at dentin bonding interface of BF before and after artificial aging cycling when used for class V cavity restoration in vitro. Cavities were prepared in human premolars and restored with either Bondfill SB or Z100 (group SZ). Quantitative data were analyzed by t-test (α = 0.05). Before cycling, there was no significant differences between groups for perfect margin and modes of failure. After cycling, SZ showed a higher (p = 0.002) perfect margin value (55.08 ± 15.20%) and less (p = 0.01) adhesive failure (35.35 ± 15.02%) to enamel than BF (25.15 ± 12.47% and 61.78 ± 15.41%, respectively). BF exhibited less (p = 0.01) adhesive failure (12.89 ± 5.58%) to dentin than SZ (44.17 ± 17.50%). BF showed more cohesive failures at both enamel (12.01 ± 3.65%) (p < 0.0001) and dentin (9.58 ± 3.14%) (p = 0.02) sides than SZ (0.77 ± 1.21% and 4.68 ± 1.39%, respectively). Transmission electron microscope (TEM) showed that hybrid layers in SZ and BF were around 0.5 μm thick. Before cycling, more silver deposits were found at dentin bonding interface in SZ. After cycling, the deterioration in SZ mostly occurred at the bottom and on the surface of the hybrid layer. While in BF, the deterioration occurred at the bottom of the hybrid layer and in Bondfill SB. BF showed a more reliable dentin bonding after artificial aging and might buffer the cervical stress concentration. Bondfill SB may be a new promising choice for long-term success of cervical lesions restoration. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2050-2056, 2019.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system

Objective

The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system.

Material and Methods

Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive).

Results

PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths.

Conclusion

A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study.

Current status of direct pulp-capping materials for permanent teeth

Direct pulp-capping is a method for treating exposed vital pulp with dental material to facilitate the formation of reparative dentin and to maintain vital pulp. Two types of pulp-capping materials, calcium hydroxide and mineral trioxide aggregate, have been most commonly used in clinics, and an adhesive resin has been considered a promising capping material. However, until now, there has been no comprehensive review of these materials. Therefore, in this paper, the composition, working mechanisms and clinical outcome of these types of pulp-capping materials are reviewed.

Evaluation of five primers and two opaque resins for bonding ceria-stabilized zirconia/alumina nanocomposite

The purpose of this study was to evaluate the effect of five primers [Super-Bond C&B Monomer (SB), Clearfil Ceramic Primer, Alloy Primer, M.L. Primer, and AZ Primer] and two undercoating opaque resins [Super-Bond C&B (S-opaque) and Ceramage Pre-opaque (C-opaque)] on the bonding of a resin composite veneering material to a ceria-stabilized tetragonal zirconia polycrystals/alumina nanocomposite (Ce-TZP/Al₂O₃). Disk-shaped specimens of Ce-TZP/Al₂O₃ were sandblasted with alumina and primed. The undercoating opaque resins and resin composites were subsequently applied to the specimen, and then light cured. After 5000 thermocycles at 4°C and 60°C, shear bond strengths were determined. Data were analyzed using analysis of variance, Tukey–Kramer honest significant difference test, and Student t test (n = 10, α = 0.05). With the exception of SB/S-opaque, all S-opaque groups exhibited significantly higher bond strengths than C-opaque groups. The use of S-opaque resin is recommended when veneering frameworks made of Ce-TZP/Al₂O₃.

Effects of tributylborane-activated adhesive and two silane agents on bonding computer-aided design and manufacturing (CAD/CAM) resin composite

The present study was conducted to evaluate the effects of an experimental adhesive agent [methyl methacrylate-tributylborane liquid (MT)] and two adhesive agents containing silane on the bonding between a resin composite block of a computer-aided design and manufacturing (CAD/CAM) system and a light-curing resin composite veneering material. The surfaces of CAD/CAM resin composite specimens were ground with silicon-carbide paper, treated with phosphoric acid, and then primed with either one of the two silane agents [Scotchbond Universal Adhesive (SC) and GC Ceramic Primer II (GC)], no adhesive control (Cont), or one of three combinations (MT/SC, MT/GC, and MT/Cont). A light-curing resin composite was veneered on the primed CAD/CAM resin composite surface. The veneered specimens were subjected to thermocycling between 4 and 60 °C for 10,000 cycles, and the shear bond strengths were determined. All data were analyzed using analysis of variance and a post hoc Tukey-Kramer HSD test (α = 0.05, n = 8). MT/SC (38.7 MPa) exhibited the highest mean bond strengths, followed by MT/GC (30.4 MPa), SC (27.9 MPa), and MT/Cont (25.7 MPa), while Cont (12.9 MPa) and GC (12.3 MPa) resulted in the lowest bond strengths. The use of MT in conjunction with a silane agent significantly improved the bond strength. Surface treatment with appropriate adhesive agents was confirmed as a prerequisite for veneering CAD/CAM resin composite restorations.

Periodontal tissue repair after sealing of the gap in vertical root fracture

The aim of this study was to determine whether sealing of fracture gap using adhesive resin through the root canal can prevent inflammation of periodontal tissue, and resealing the incompletely sealed fracture gap from outside can resolve such inflammation in experimentally created vertical root fractures. Vertical root fractures were created in incisor of beagles. In the experimental group, the fracture gap was sealed through the root canal with adhesive resin. After 5 weeks, sites with the clinical attachment level ≥4 mm were further divided randomly into the poor-replanting group and the poor-untreated group. In the poor-replanting group, the tooth was extracted and replanted after resealing the fracture gap with adhesive resin from the outer surface. Sites with clinical attachment level ≤3 mm after 5 weeks were considered as the satisfactory group. The poor-untreated group and the satisfactory group were subjected to no further treatment. The clinical attachment level was evaluated at baseline and after 2, 5, and 9 weeks. After 9 weeks, histological measurements were made to determine the length of the epithelial downgrowth and the area of alveolar bone resorption. The clinical attachment level and the area of bone resorption were significantly smaller in the poor-replanting group and the satisfactory group than in the poor-untreated group (p < 0.05). The results indicate the possibility that periodontal inflammation along the fracture line can be prevented and improved if the fracture gap is sealed.

In vitro evaluation of adhesive characteristics of 4-META/MMA-TBB resin with organic filler

OBJECTIVES

A commercial restorative material, BondfillSB (BF), is a modification of 4-META/MMA-TBB resin cement. BF uses a self-etching primer and added pre-polymerized organic fillers. We compared BF with another self-etching system, EasyBond (EB), in shear bond strength, bonded interface characteristics to human dentin and contraction gap when used in bulk-filling.

METHODS

Shear bond strength of BF and EB + Z100 (Z), bonded by different experience-level operators, was evaluated. Bonded interfaces were characterized by SEM, AFM, and AFM based nano-indentation. Contraction gaps (CG) at 0h and 24h after polymerization were evaluated for BF or EB bulk filled class I cavities. To meet the clinical recommendation, BF's powder was replaced by experimental radioopaque powder (BFO) for the CG study. EB was used with Z (EBZ) or with a resin marketed for bulk-fill base (SureFil-SDR-flow (EBSF)).

RESULTS

Shear bond strengths (Mean ± Standard Deviation (S.D.)) of BF (37.4 ± 2.6 MPa; n=36) were higher and less variable than EBZ (18.2 ± 7.6 MPa; n=36) (p<0.0001, One-way ANOVA). Weibull characteristic strength (η) differed significantly between materials (p<0.0001) but not between operators (p=0.90). EBZ often had non-uniform interfaces and a wider band of reduced elastic modulus (E) of greater than 20 μm across the interface. BF had uniform interfaces and a smaller width of affected dentin under the interface (∼1 μm). There was a difference in dentin-E between EBZ and BF up to 9 μm from the interface (mixed-effects model; P=0.03). A stratified linear regression model used for CG. EBSF and BFO showed significantly smaller CG than EBZ at time 0. None of three combinations showed any significant change between 0h-CG and 24h-CG.

SIGNIFICANCE

BF possessed bonding characteristics required to serve as a restorative.