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A growing class of multifunctional porous materials termed metal–organic frameworks (MOFs) has attracted attention for immobilization of biomolecules via self-assembly of inorganic and organic building blocks. Herein, we report the rapid formation of MOF shells surrounding collagen-degrading enzymes by using a biomimetic mineralization approach. Bacterial collagenase, which is functionally related to endogenous proteases in the human body, was used as a nucleating agent to induce the mineralization of zeolitic imidazolate framework-8 (ZIF-8) as a crystalline shell. This zinc-based MOF material was selected due to its remarkable stability under physiological conditions and good biocompatibility. The straightforward, water-based synthesis yielded microporous collagenase-embedded ZIF-8 particles. Once immobilized inside the biomimetically mineralized MOF, the protease presented limited catalytic activity, being ineffective in the proteolysis of a collagen-like peptide. In conclusion, biomimetic mineralization of ZIF-8 using collagenase not only provided immobilization of the enzyme, but also enabled the control of its activity. This synthetic approach provides a potentially useful concept in the prevention of proteolytic activity involved in the degradation of collagen matrices in living organisms.

Rhodamine B (RB) is commonly used to evaluate dental polymers, including dental bonding systems (DBS). For reliability assessments, its effect should not only allow visualization of the dentin-polymer interface but also must not interfere with the bonding of the DBS to dentin as measured by the microtensile bond strength and hardness tests.Flat human dentin surfaces were prepared and randomly distributed (n = 10) into six groups: Adper Scotchbond Multi-Purpose (MP) or Clearfil SE Bond (SE) in concentrations of none/control, 0.02 or 0.1 mg/mL. These combinations were prepared through ethanol dissolution to improve their penetration into the dentin. All specimens were fabricated with Filtek Z250 (n = 10) and prepared for a microtensile bond test (μTBS) (0.5 mm/min) after 7 days and 6 months. The failure modes were determined using a stereomicroscope (×40). For the hardness test, flat human dentin blocks were prepared and treated as previously described (n = 6). The specimens were stored at 37 °C/48 h and were tested (Knoop indenter - 25 gF/10 s). Data were analyzed with two-way ANOVA and Tukey tests for multiple comparisons (α = 0.05). The effect of time was evaluated using the Student t-test.For 7-day μTBS, both the DBS and RB concentrations were significant factors (p 0.01). After 6 months, only the RB concentration was significantly different. Adhesive failures were prevalent for all groups. Regarding hardness, the DBS differed only with the use of 0.10 mg/mL of RB.Ethanol-dissolved rhodamine B in concentrations of 0.02 and 0.10 mg/mL in non-simplified adhesives can affect the physical-mechanical properties of functional monomer-based systems rather more than those of BisGMA systems.

Simplified dentin-bonding systems are clinically employed for most adhesive procedures, and they are prone to hydrolytic degradation. Objective This study aimed to investigate the effect of laser diode irradiation on the degree of conversion (DC), water sorption (WS), and water solubility (WSB) of these bonding systems in an attempt to improve their physico-mechanical resistance. Material and Methods Two bonding agents were tested: a two-step total-etch system [Adper™ Single Bond 2, 3M ESPE (SB)] and a universal system [Adper™ Single Bond Universal, 3M ESPE (SU)]. Square-shaped specimens were prepared and assigned into 4 groups (n=5): SB and SU (control groups – no laser irradiation) and SB-L and SU-L [SB and SU laser (L) – irradiated groups]. DC was assessed using Fourier transform infrared spectroscopy with attenuated total reflectance. Additional uncured resin samples (≈3.0 µL, n=5) of each adhesive were also scanned for final DC calculation. For WS/WSB tests, similar specimens (n=10) were prepared and measured by monitoring the mass changes after dehydration/water storage cycles. For both tests, adhesive fluids were dropped into standardized Teflon molds (6.0×6.0×1.0 mm), irradiated with a 970-nm laser diode, and then polymerized with an LED-curing unit (1 W/cm2). Results Laser irradiation immediately before photopolymerization increased the DC (%) of the tested adhesives: SB-L>SB>SU-L>SU. For WS/WSB (μg/mm3), only the dentin bonding system (DBS) was a significant factor (pSU. Conclusion Irradiation with a laser diode improved the degree of conversion of all tested simplified dentin bonding systems, with no impact on water sorption and solubility.

The technique of enamel microabrasion is considered an aesthetic alternative conservative and effective for stain removal or surface irregularities of the enamel and different materials or pastes can be used for this purpose Objetives: The objective of this study was to compare the efficiency of the technique of enamel microabrasion using two different pastes at removing hypoplastic stains by fluorosis. Methods: The female patient, 18 years, was submitted to enamel microabrasion, and in the right half of the maxilla was manipulated in the proportion of 1:1 by volume a paste of pumice (SSWhite) and 37% phosphoric acid (Etch Alpha, DFL), and in the left half of the maxilla used paste based on hydrochloric acid and 6.6% silicon carbide (Micropol, DMC Equipment Ltd.). In both hemi-arches was performed the same clinical protocol and repeated three times, by the application of 1.0 mm thickness of paste and realized the enamel microabrasion through mechanical friction with rubber cup at low speed for 10 seconds. Then, the teeth were polished with felt disc and diamond paste, and topical fluoride APF 1.23% for 3 minutes was applied. Results: The clinical outcome was similar for both hemi-arches, regardless of the used technique. The success in removing stains on tooth enamel is directly related to a correct diagnosis and accurate indication of microabrasion technique. Conclusions: It can be concluded that the two pastes used in the enamel microabrasion were effective for removing intrinsic stains from fluorosis, with similar results and with the re-establishment of aesthetics of the teeth involved.

Made available in DSpace on 2018-11-26T17:20:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fluorescent dyes like Rhodamine B (RB) have been used to identify the spatial distribution of adhesive restorative materials in the tooth/restoration interface. Potential effects of the addition of RB to dental adhesives were addressed in the past, but no further information is available on how to determine suitable concentrations of RB in these bonding agents for imaging in the confocal laser scanning microscope. This study provides systematical strategies for adding RB to viscous dental adhesive resins, focusing on the determination of the lowest range of dye concentrations necessary to achieve an acceptable image of the dentin/adhesive interface. It was demonstrated that optimized images of the resin distribution in dentin can be produced with 0.1-0.02 mg/mL of RB in the (tested) adhesives. Our approaches took into account aspects related to the dye concentration, photophysical parameters in different host media, specimen composition and morphology to develop a rational use of the fluorescent agent with the resin-based materials. Information gained from this work can help optimize labeling methods using dispersions of low-molecular-weight dyes in different monomer blend systems. Univ Sao Paulo, Bauru Sch Dent, Dept Operat Dent Endodont & Dent Mat, BR-17012901 Bauru, SP, Brazil Univ Estadual Paulista, Inst Chem, Dept Inorgan Chem, BR-14800060 Araraquara, SP, Brazil Univ Sao Paulo, Bauru Sch Dent, Dept Prosthodont, BR-17012901 Bauru, SP, Brazil Univ Sao Paulo, Sch Dent, Dept Operat Dent, BR-05508000 Sao Paulo, SP, Brazil Univ Estadual Paulista, Inst Chem, Dept Inorgan Chem, BR-14800060 Araraquara, SP, Brazil FAPESP: 2011/14971-2 FAPESP: 2012/13160-3 FAPESP: 2013/13161-2

Objective This study investigated the effect of the fluorescent dye rhodamine B (RB) for interfacial micromorphology analysis of dental composite restorations on water sorption/solubility (WS/WSL) and microtensile bond strength to dentin (µTBS) of a 3-step total etch and a 2-step self-etch adhesive system. Material and Methods The adhesives Adper Scotchbond Multi-Purpose (MP) and Clearfil SE Bond (SE) were mixed with 0.1 mg/mL of RB. For the WS/WSL tests, cured resin disks (5.0 mm in diameter x 0.8 mm thick) were prepared and assigned into four groups (n=10): MP, MP-RB, SE, and SE-RB. For µTBS assessment, extracted human third molars (n=40) had the flat occlusal dentin prepared and assigned into the same experimental groups (n=10). After the bonding and restoration procedures, specimens were sectioned in rectangular beams, stored in water and tested after seven days or after 12 months. The failure mode of fractured specimens was qualitatively evaluated under optical microscope (x40). Data from WS/WSL and µTBS were assessed by one-way and three-way ANOVA, respectively, and Tukey’s test (α=5%). Results RB increased the WSL of MP and SE. On the other hand, WS of both MP and SE was not affected by the addition of RB. No significance in µTBS between MP and MP-RB for seven days or one year was observed, whereas for SE a decrease in the µTBS means occurred in both storage times. Conclusions RB should be incorporated into non-simplified DBSs with caution, as it can interfere with their physical-mechanical properties, leading to a possible misinterpretation of bonded interface.

Laser irradiation after the immediate application of dentin bonding systems (DBSs) and prior to their polymerization has been proposed to increase bond strength. The objective of this study was to evaluate the effect of diode laser irradiation (λ = 970 nm) on simplified DBSs through microtensile bond strength tests. Forty healthy human molars were randomly distributed among four groups (n = 10) according to DBSs used [Adper™ SingleBond 2 (SB) and Adper™ EasyOne (EO)], and the respective groups were irradiated with a diode laser (SB-L and EO-L). After bonding procedures and composite resin build-ups, teeth were stored in deionized water for 7 days and then sectioned to obtain stick-shaped specimens (1.0 mm2). The microtensile test was performed at 0.5 mm/min, yielding bond strength values in MPa, which were evaluated by two-way ANOVA followed by Tukey’s test (p < 0.05) for individual comparisons. For both adhesive systems, diode laser irradiation promoted significant increases in bond strength values (SB: 33.49 ± 6.77; SB-L: 43.69 ± 8.15; EO: 19.67 ± 5.86; EO-L: 29.87 ± 6.98). These results suggest that diode laser irradiation is a promising technique for achieving better performance of adhesive systems on dentin.

This study evaluated the influence of 2% chlorhexidine digluconate (CHX) on the bond strength (BS) of a glass-fibre post to the root canal, regarding the cements (dual-cured resin or resin-modified glass-ionomer cement), the root thirds and the time of storage.Eighty bovine roots were selected and endodontically treated, before being randomly assigned to the following groups according to the luting protocol: ARC (RelyX ARC); ARC+CHX; RL (RelyX Luting 2); and RL+CHX. After 24 h of luting, the roots were sliced to obtain 1 mm-thick slices. Half of each group was submitted to either 7-day or 6-month storage in artificial saliva (n=10). The specimens were subjected to push-out tests with a crosshead speed of 0.5 mm/min. The data were analysed with four-way ANOVA and Tukey's test (P≤0.05). The failure modes were analysed with a digital microscope (50× and 200×).ARC yielded a significantly higher BS compared to RL (P0.001). Despite CHX exerted a significant effect; it depends on the interaction with the luting cement and time (P0.001). Thus, CHX decreased the values of BS to those of ARC after 6 months (P0.001). On the 7th day of storage, the ARC+CHX presented higher BS to the cervical and middle thirds compared to RL+CHX (P=0.012). Time solely was not a significant factor (P=0.081). Adhesive cement-dentine type and mixed failures were predominant modes for the ARC groups. For the RL groups, the main failures were adhesive cement-post and mixed modes.Glass-fibre posts luted with RelyX ARC dual-cure resin cement exhibited higher BS than those luted with RelyX Luting 2 resin-modified glass-ionomer cement. Furthermore, CHX was not effective to improve the BS and negatively affected the BS of RelyX ARC after 6 months of storage.The use of chlorhexidine solution seems not to improve the bond strength of fibre posts to root canals, disregarding the composition of the luting cement.