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.

Management of developmental enamel defects in the primary dentition

This study attempted to identify appropriate materials for restoration of enamel defects in the primary dentition, which were classified by severity and region with the modified developmental defects of enamel index. To identify the most appropriate materials, we used restorative materials to protect teeth and evaluated clinical outcomes of restoration. Three materials were used for restoration or repair after dislodgement of restorations. Our findings in this case suggest that, because of its durability and esthetic advantages, adhesive resin is beneficial for patients with enamel defects, particularly for restorations of less than two-thirds of the extent of the defect.

Wear characteristics of trimethylolpropane trimethacrylate filler-containing resins for the full crown restoration of primary molars

Although the demand for aesthetic restoration of primary molars has increased, the full-crown restorations using resin and the details of the wear characteristics of trimethylolpropane trimethacrylate (TMPT) filler containing resins for primary molars are not well understood. This study was conducted to determine whether new light-cured composite resin (Fantasista) and 4-META/MMATBB resin (Bondfill SB) are appropriate for full crown restoration of primary molars by evaluating their wear characteristics. Both resins products contain TMPT filler. The properties of the resins were evaluated through in vitro impacting-sliding wear tests; the wear properties of the opposing enamel specimens used in the tests were also studied. The properties of the resins were compared with those of Litefill, MetafilC, and Clearfil FII, which had been evaluated previously. Fantasista exhibited simple shape of wear that was suggestive of a higher wear resistance than that of Litefill. Fantasista caused the least damage to the antagonistic primary enamel.

Comparison of access-hole filling materials for screw retained implant prostheses: 12-month in vivo study

BACKGROUND

Screw retained implant prostheses seem to be an efficient restorative method to prevent peri-implantitis caused by cement excess around the abutment. The drawback of the screw-retained prostheses is the difficulty to realize an efficient access-hole filling functionally and aesthetically. Up to now, few in vitro and in vivo studies were reported in the literature. The aim of this study was to evaluate clinical performances of two direct filling materials through a period of 12 months.

METHODS

To pursue a previous in vitro evaluation, this in vivo 12 months prospective study followed up and compared the access-hole filling integrity of a modified 4-META (4-methacryloxyethyl trimellitate anhydride)/MMA-TBB (methyl methacrylate-tri-n-butyl borane) - based resin (M4M) and a photo-polymerizing nano-hybrid composite resin (CR). Twenty-eight access-holes were filled with both materials respectively, then impressions and intra-oral photographs were taken at T = 0, T = 1 M (month), 3, 6, and 12 M. The access-hole surface measurement and the margin analysis (depth and angle) were carried out. The VAS (visual analogue scale) value on marginal discoloration and integrity at the baseline T = 0 and T = 12 M was recorded.

RESULTS

The mean values of the surface areas changes from T = 1 to T = 12 M were 83.3 ± 11.5% for group CR and 77.1 ± 13.1% for group M4M, respectively. (Mann-Whitney test p < 0.05, p = 0.046). The mean marginal depth at T = 12 M for group CR were 141.2 ± 125.5 μm and 132.1 ± 107.8 μm for the group M4M, respectively. (Mann-Whitney test p > 0.05, p = 0.58). The mean values of the angle formed at the margin (T = 12 M) were for group CR 39.5 ± 19.4° and 28.2 ± 17.2° for group M4M, respectively (Mann-Whitney test p < 0.0001). The photographical analysis by VAS values showed no significant difference between CR and M4M groups (Mann-Whitney test p > 0.05, p = 0.848).

CONCLUSIONS

Based on intra- and extra-oral evaluations with the limitation, both CR and M4M combined with a ceramic primer are indicated as promising materials to fill the access-hole. Further long-term investigation is necessary to confirm this finding.

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.

In vitro evaluation of a modified 4-META/MMA-TBB resin for filling access holes of screw-retained implant prostheses

This study evaluates a modified 4-META/MMA-TBB resin (M4M) as a candidate material for filling screw-retained implant access hole. Its characteristics were compared with a conventional composite resin (CR) with or without a bonding agent (BA) or a ceramic primer (CP). Ceramic blocks were divided into five groups, including (A) CR, (B) CR with BA, (C) CR with CP and BA, (D) M4M, and (E) M4M with CP. Shear bond strengths were measured after 5000 times of thermocycling. Groups A, B, and D were excluded from further tests as they showed no adhesion. A cylindrical cavity (2.5 mm diameter, 3 mm depth) simulating access hole was prepared in a ceramic block and glazed to evaluate micro-leakage and wear test of groups C and E. The results were statistically analyzed with Mann-Whitney test (p  <  0.05). Shear bond strength of groups C (7.6 ± 2.2 MPa) and E (8.6 ± 1.0 MPa) was not significantly different. In micro-leakage analysis, average wear depth and wear volume, group E (7.5 ± 3.3%, 59.3 ± 12.9 μm, 0.16 ± 0.04 mm(3) ) showed significantly lower values than those of group C (45.6 ± 24.4%, 76.0 ± 16.4 μm, 0.28 ± 0.03 mm(3) ). It is suggested that the combination of CP and M4M can be one of feasible systems to fill the ceramic access holes of the implant upper structure.

Adhesive performance of silver-palladium-copper-gold alloy and component metals bonded with organic sulfur-based priming agents and a tri-n-butylborane initiated luting material

OBJECTIVE

The purpose of the current study was to evaluate the effect of thione-based metal priming agents on the adhesive behavior of a Ag-Pd-Cu-Au alloy and component metals bonded with an acrylic resin.

MATERIALS AND METHODS

Disk specimens (10 mm in diameter by 3 mm thick) were prepared from a silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell M.C.12), high-purity silver, palladium, copper and gold. Four single-liquid priming agents containing organic sulfur compound (Alloy Primer, Metaltite, M.L. Primer and V-Primer) and three acidic priming agents (All Bond II Primer B, Estenia Opaque Primer and Super-Bond Liquid) were assessed. The metal specimens were flat-ground with abrasive papers, primed with one of the agents and bonded with a tri-n-butylborane initiated resin. The shear bond strengths were determined both before and after repeated thermocycling (5°C and 55°C, 1 min each, 20,000 cycles). The results were statistically analyzed with a non-parametric procedure (p = 0.05 level).

RESULTS

The post-thermocycling bond strengths in MPa (median; n = 11) associated with the Alloy Primer, Metaltite, M.L. Primer and V-Primer materials were, respectively, 20.8, 22.8, 17.8 and 18.4 for the Ag-Pd-Cu-Au alloy; 19.6, 21.9, 14.4 and 20.1 for silver; 5.4, 4.5, 12.8 and 5.3 for palladium; 17.1, 19.2, 0.7 and 6.6 for copper; and 18.5, 17.7, 22.8 and 15.4 for gold.

CONCLUSIONS

It can be concluded that the use of the four priming agents, which are based on organic sulfur compounds, effectively enhanced bonding to the Ag-Pd-Cu-Au alloy and the component metals, although the bonding performance varied among the priming agents and metal elements. The priming agents appeared to have more of an effect on the alloy, silver and gold than on the palladium and copper.