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Push-out bond strength of calcium-silicate cements following Er:YAG and diode laser irradiation of root dentin.
Mohammadian, F, Soufi, S, Dibaji, F, Sarraf, P, Chiniforush, N, Kharrazifard, MJ
Lasers in medical science. 2019;(1):201-207
Abstract
This study aimed to compare the effects of diode and Er:YAG laser irradiation of root dentin on push-out bond strength of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cements. An in vitro experimental study was conducted on 90 dentin discs, cut out of freshly extracted human teeth. The discs were instrumented to obtain 1.3-mm lumen diameter. Then, they were randomly divided into six groups (n = 15). Groups 1 and 4 subjected to diode laser (Wiser, Doctor Smile, Italy) (980 nm, 1 W, continuous mode) for 10 s and filled with MTA and CEM cements. Groups 2 and 5 subjected to Er:YAG laser (Deka, Italy) (2940 nm, 1 W, 10 Hz, 230 μs) for 10 s and filled with MTA and CEM cements. Groups 3 and 6 (control groups) were filled with MTA and CEM cements without laser irradiation. After 7 days, push-out bond strength test was performed using a universal testing machine in order to evaluate the adhesion of the biomaterials to dentin. The samples were evaluated under a light microscope at × 40 magnification to determine the mode of fracture. Data were analyzed using two-way ANOVA. The highest push-out bond strength (8.76 ± 3.62 MPa) was noted in group 1 (diode/MTA), which was significantly higher than the other groups (P < 0.001). The lowest bond strength (2.61 ± 0.81) was noted in group 6 (control/CEM). Diode laser significantly increased the bond strength of both cements (P < 0.05), but Er:YAG laser irradiation only increased the bond strength of CEM and had no significant effect on MTA (P = 0.603). The bond strength of MTA control group was higher than that of CEM control group (P = 0.001). Push-out bond strength of endodontic cements can be affected by dentin conditioning with diode 980 nm and Er:YAG laser. Nine hundred eighty-nanometer diode laser irradiation is recommended to increase the bond strength of endodontic cements particularly the CEM cement to dentin.
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Quantitative/qualitative analysis of adhesive-dentin interface in the presence of 10-methacryloyloxydecyl dihydrogen phosphate.
Zhou, J, Wurihan, , Shibata, Y, Tanaka, R, Zhang, Z, Zheng, K, Li, Q, Ikeda, S, Gao, P, Miyazaki, T
Journal of the mechanical behavior of biomedical materials. 2019;:71-78
Abstract
Dental adhesive provides effective retention of filling materials via adhesive-dentin hybridization. The use of co-monomers, such as 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), is thought to be crucial for hybridization owing to their ionic-binding to calcium and co-polymerization in the polymerizable adhesives. Optimal hybridization partly depends on the mechanical properties of polymerized adhesives, which are likely to be proportional to the degree of conversion ratio. This study assessed the correlation between polymerization quality and mechanical properties at the adhesive-dentin interfaces in the presence or absence of 10-MDP. In situ Raman microspectroscopy and nanoindentation tests were used concurrently to quantify the degree of conversion ratio and dynamic mechanical properties across the adhesive-dentin interfaces. Despite the excellent diffusion and apparent higher degree of co-polymerization, 10-MDP reduced the elastic modulus of the interface. The higher viscoelastic properties of the adhesive are suggestive of poor polymerization, namely polymerization linearity related to the long carboxyl chain of 10-MDP. Such reduced mechanical integrity of hybridization could also be associated with the inhibition of nano-layering between 10-MDP and mineralized tissue in the presence of hydroxyethyl methacrylate (HEMA). This potential drawback of HEMA necessitates further qualitative/quantitative characterization of adhesive-dentin hybridization using a HEMA-free/low concentration experimental 10-MDP monomer, which theoretically possesses superior chemical bonding potential to the current HEMA-rich protocol.
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The recovery effect of proanthocyanidin on microtensile bond strength to sodium hypochlorite-treated dentine.
Wang, Y, Chen, C, Zang, HL, Liang, YH
International endodontic journal. 2019;(3):371-376
Abstract
AIM: To evaluate the recovery effect of proanthocyanidin (PA) on microtensile bond strength (μTBS) to sodium hypochlorite (NaOCl)-treated dentine. METHODOLOGY Fifty-five freshly extracted third molars with intact dental crowns, no caries or restorations were sectioned to expose a sound middle layer of dentine and were randomly divided into 11 groups. In the blank control group, dentine surfaces were immersed in deionized water for 20 min. In the negative control group, dental surfaces were immersed in 5.25% NaOCl for 20 min. In the other nine experimental groups, after immersion for 20 min in 5.25% NaOCl, followed by PA (5%, 10%, or 15%) treatment for 1, 5 min or 10 min. The NaOCl solution was renewed every 5 min. Then dentine surfaces were bonded using SE bond. Bonded samples were sectioned into dentine-resin sticks (n = 45) for microtensile bond strength testing (MPa). Failure modes were observed and classified into three types with a stereomicroscope. Microtensile bond strength data were analysed using one-way anova. The confidence interval test was performed to analyse the recovery effect of PA on bond strength to NaOCl-treated dentine. The chi-squared test was used to analyse failure mode distribution. RESULTS After use of 5.25% NaOCl for 20 min, microtensile bond strength in the negative control group decreased significantly compared with that of the untreated group (P < 0.05). After a recovery treatment of 10% PA for 10 min or 15% PA for more than 5 min, the bond strength was restored to at least 90% of baseline (P < 0.05). No recovery effect on bond strength was detected after the application of 5% PA for 1 min (P > 0.05). Adhesive fracture was found to be the most common failure mode in the NaOCl-treated group. After the recovery application of PA, the proportion of mixed failures increased significantly (P < 0.05). CONCLUSIONS Microtensile bond strength to NaOCl-treated dentine recovered after the application of either 5% PA for more than 5 min or 10% or 15% PA for more than 1 min. The application of PA before an adhesive procedure may immediately restore the compromised bond strength of NaOCl-treated dentine.
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Do ozonated water and boric acid affect the bond strength to dentin in different adhesive systems?
Akturk, E, Bektas, OO, Ozkanoglu, S, G Akin, EG
Nigerian journal of clinical practice. 2019;(12):1758-1764
Abstract
AIM: The aim of this in vitro study was to compare the effects of the application of three different cavity disinfecting agents to dentin on the micro-shear bond strength (μ-SBS) of one self-etch and two universal adhesive systems. MATERIALS AND METHODS In total, 120 caries-free human permanent molar teeth were used in this study. Mid-coronal dentin surfaces were revealed by cutting occlusal enamel and a standard smear layer was obtained by using 600-800-1200 grid silicon carbide abrasive papers. Specimens were randomly assigned to four groups according to the disinfectant used: Group 1: Control (no disinfectant); Group 2: 2% chlorhexidine based (Consepsis); Group 3: 10 ppm ozonated water (TeknO3zone); Group 4: 5% boric acid (Handmade). Each group was divided into three subgroups according to the type of adhesive (Clearfil SE Bond, OptiBond XTR, and Tokuyama Universal). Specimens were bonded using either Clearfil SE Bond, OptiBond XTR or Tokuyama Universal, which were employed according to the manufacturer's instructions. Resin composite microcylinders were bonded using Tygon® tubes for μ-SBS testing. After specimens were stored for 24 h, at 37°C in distilled water, μ-SBS test was measured with a universal test machine (LF Plus, Lloyd, Instrument). μ-SBS results were analyzed by one-way analysis of variance (ANOVA) and Tukey's tests. RESULTS When the mean microshear bond strength values of the control group were compared, the difference between the subgroups was not significant (P < 0.05). When the mean microshear bond strength values of the chx, ozonated water, and boric acid were compared, the difference between Clearfil SE Bond and Tokuyama Universal was significant (P < 0.05) and the difference between the other groups was not significant (P > 0.05). CONCLUSION Ozonated water and boric acid may be as an alternative to other materials used as cavity disinfectants.
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Microcomputed Tomography Evaluation of Dentine Mineral Concentration in Primary Molars Managed by Three Treatment Protocols.
Mijan, MC, Frencken, JE, Schwass, DR, Chaves, SB, Leal, SC
Caries research. 2018;(4):303-311
Abstract
The objectives of the study were to quantify the dentine mineral concentration (DMC) in teeth restored conventionally, according to the atraumatic restorative treatment (ART) and ultraconservative (UCT) protocols (open cavities and small ART restorations), and the DMC underneath the open cavities of teeth managed by UCT versus nontreated, open cavities. We studied 50 teeth with restorations/open cavities, 39 restored teeth (9 by conventional restorative treatment [CRT], 17 by ART, and 13 by UCT) and 16 teeth with open cavities. Each restoration/open cavity was scanned using microcomputed tomography, with 3 hydroxyapatite disks with respective densities of 1.24, 1.33, and 1.57 g/cm3 as a reference. Images were reconstructed and the greyscale images were converted into DMC values. For each restoration/open cavity, 15 measurements of dentine immediately underneath and from the corresponding area in sound dentine were taken. DMC was expressed as a percentage of the DMC of sound dentine. ANOVA and the Student t test were used for statistical analysis. The mean DMC underneath restorations of the ART protocol group (98.93%) was statistically significantly higher than that of the UCT protocol group (91.98%), but not of the CRT protocol group (91.33%). On multiple surfaces, mean DMC in the axial area (94.32%) was statistically significantly higher than in the gingival area (92.80%). The mean DMC of open cavities managed by UCT protocol (89.05%) was statistically significantly higher than in nontreated open cavities (83.90%). In conclusion, a dentine-hypermineralized area underneath ART restorations was observed. Managing open cavities with a toothbrush and fluoride toothpaste (the UCT protocol) resulted in higher mineralized dentine underneath the cavity than in nontreated open cavities.
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A zinc-doped endodontic cement facilitates functional mineralization and stress dissipation at the dentin surface.
Toledano, M, Osorio, R, Pérez-Álvarez, MC, Osorio, E, Lynch, CD, Toledano-Osorio, M
Medicina oral, patologia oral y cirugia bucal. 2018;(6):e646-e655
Abstract
BACKGROUND The purpose of this study was to evaluate nanohardness and viscoelastic behavior of dentin surfaces treated with two canal sealer cements for dentin remineralization. MATERIAL AND METHODS Dentin surfaces were subjected to: i) 37% phosphoric acid (PA) or ii) 0.5 M ethylenediaminetetraacetic acid (EDTA) conditioning prior to the application of two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite), respectively. Samples were stored in simulated body fluid during 24 h or 21 d. The intertubular and peritubular dentin were evaluated using a nanoindenter to assess nanohardness (Hi). The load/displacement responses were used for the nano-dynamic mechanical analysis to estimate complex modulus (E*) and tan delta (δ). The modulus mapping was obtained by imposing a quasistatic force setpoint to which a sinusoidal force was superimposed. AFM imaging and FESEM analysis were performed. RESULTS After 21 d of storage, dentin surfaces treated with EDTA+calcypatite, PA+calcypatite and EDTA+oxipatite showed viscoelastic discrepancies between peritubular and intertubular dentin, meaning a risk for cracking and breakdown of the surface. At both 24 h and 21 d, tan δ values at intertubular dentin treated with the four treatments performed similar. At 21 d time point, intertubular dentin treated with PA+oxipatite achieved the highest complex modulus and nanohardness, i.e., highest resistance to deformation and functional mineralization, among groups. CONCLUSIONS Intertubular and peritubular dentin treated with PA+oxipatite showed similar values of tan δ after 21 d of storage. This produced a favorable dissipation of energy with minimal energy concentration, preserving the structural integrity at the dentin surface.
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Response of periodontium to mineral trioxide aggregate and Biodentine: a pilot histological study on humans.
Tirone, F, Salzano, S, Piattelli, A, Perrotti, V, Iezzi, G
Australian dental journal. 2018;(2):231-241
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Abstract
BACKGROUND The aim of this study was to investigate for the first time the histological response of human periodontium to mineral trioxide aggregate (MTA) and Biodentine. METHODS Six patients scheduled for implant full-arch rehabilitation were randomly assigned to one of the two test groups: MTA or Biodentine treatment. For each patient, two teeth scheduled for strategic extraction were randomly assigned either to the test or to the control treatment. A lateral perforation was drilled on the root and either repaired with MTA/Biodentine or filled with gutta-percha(control). Three months later, the teeth were extracted along with the coronal third of the alveolar bone and a portion of gingival tissue, while performing implant placement, and processed for histological analysis. RESULTS Biodentine resulted in less extrusion into the periodontal environment. All the materials showed good biocompatibility. A new mineralized cementum-like tissue incorporating periodontal fibres was visible in all cases treated with MTA. A small amount of new mineralized tissue was found in two Biodentine cases but not in control cases. Biodentine resulted in less damage to the periodontal ligament. CONCLUSIONS Bioactivity and biocompatibility of MTA were confirmed in human models. Biodentine proved to be biocompatible, but it seems not to induce cementum regeneration.
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The effect of endodontic irrigants on the microtensile bond strength of different dentin adhesives.
Dikmen, B, Tarim, B
Nigerian journal of clinical practice. 2018;(3):280-286
Abstract
OBJECTIVES The aim of this study was to determine the influence of irrigants on bond strength of adhesive systems. MATERIALS AND METHODS Superficial dentin surfaces of 60 extracted molars were divided into 15 groups, according to irrigants and adhesives. In the control groups, surfaces were irrigated with distilled water. In experimental groups, sodium hypochlorite (NaOCl), ethylenediaminetetraacetic acid (EDTA) + NaOCl, chlorhexidine (CHX), and NaOCl + sodium ascorbate were used as irrigants. Resin composites were then built up using Single Bond, Clearfil SE Bond, and Xeno 3 as adhesives. The microtensile bond strength of groups was determined. Data were statistically analyzed by two-way analysis of variance (ANOVA), one-way ANOVA, and the Bonferroni test. RESULTS NaOCl reduced bond strength of Single Bond and Clearfil SE Bond (P < 0.01). For all adhesive systems, EDTA + NaOCl-treated groups exhibited lower bond strength than control groups (P < 0.01). CHX decreased bond strength of Single Bond (P < 0.01). Application of sodium ascorbate improved compromised bond strength to NaOCl-treated dentin (P < 0.01). CONCLUSION Different irrigants had several effects on bonding of different adhesives. Sodium ascorbate after NaOCl could restore compromised bond strengths.
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Bacterial colonization in the apical part of extracted human teeth following root-end resection and filling: a confocal laser scanning microscopy study.
Tsesis, I, Elbahary, S, Venezia, NB, Rosen, E
Clinical oral investigations. 2018;(1):267-274
Abstract
OBJECTIVES The purpose of this study was to evaluate Enterococcus faecalis colonization at the apical part of root canals following root-end resection and filling using confocal laser scanning microscopy (CLSM). MATERIALS AND METHODS The apical 3-mm root-ends of 55 extracted single rooted human teeth were resected, and 3-mm retrograde cavities were prepared and filled using either mineral trioxide aggregate (MTA), intermediate restorative material (IRM), or Biodentine (n = 10 each); 25 teeth served as controls. The roots were placed in an experimental model, sterilized, and coronally filled with E. faecalis bacterial suspension for 21 days. Then, the apical 3-mm segments were cut to get two slabs (coronal and apical). The slabs were stained using LIVE/DEAD BacLight Bacterial Viability Kit and evaluated using CLSM. RESULTS The fluorescence-stained areas were larger in the bucco-lingual directions compared with the mesio-distal directions (p < 0.05). The mean and maximal depths of bacterial colonization into the dentinal tubules were 755 and 1643 μm, respectively, with no differences between the root-end filling materials (p > 0.05). However, more live bacteria were found in the MTA group in comparison to IRM and Biodentine groups (p < 0.05). CONCLUSIONS CLSM can be used to histologically demonstrate bacterial root-end colonization following root-end filling. This colonization at the filling-dentine interfaces and deeper into the dentinal tubules may be inhomogeneous, favoring the bucco-lingual aspects of the root. CLINICAL RELEVANCE Following root-end resection and filling bacterial colonization may lead to inflammatory reactions at the periapical tissues; the viability of the colonized bacteria may be affected by the type of root-end filling material.
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Randomised clinical trial to evaluate changes in dentine tubule occlusion following 4 weeks use of an occluding toothpaste.
Seong, J, Parkinson, CP, Davies, M, Claydon, NCA, West, NX
Clinical oral investigations. 2018;(1):225-233
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Abstract
OBJECTIVES The objective of this study is to determine whether a silicone impression material could precisely replicate dentine tubule changes following 4 weeks toothbrushing with occluding or non-occluding toothpaste and whether changes reflected hypersensitivity clinical assessment. MATERIALS AND METHODS This was a single site, examiner blind, parallel, two treatment arm, randomised clinical trial. Participants were healthy, ≥18, with ≥1 sensitive tooth with exposed dentine, Schiff sensitivity score ≥2, and patent tubules with dentine occlusion score 4-5 as determined by scanning electron microscopy of replica impressions. Nine participants received Sensodyne® Rapid Relief (occluding toothpaste) and 10 Crest® Decay Prevention (non-occluding toothpaste), and were re-evaluated for sensitivity and occlusion score after two timed minutes and 4 weeks twice-daily home brushing. RESULTS Occlusion scores did not correlate significantly with pain scores, but correlations were positive and impressions showed characteristic dentine tubule patency and occlusion. After 4 weeks, thermal VAS was significantly lower than baseline for the non-occluding toothpaste; all other pain scores were significantly lower for both treatments. Dentine occlusion scores also decreased after 4 weeks of either treatment, but did not achieve significance (p = 0.0625). CONCLUSIONS Both toothpastes reduced clinical sensitivity and increased tubule occlusion. It is hypothesised that during impression, taking some material may have sheared off and occluded tubules resulting in false positives. CLINICAL RELEVANCE This study has demonstrated that a silicone impression material can accurately replicate the dentine surface to demonstrate dentine tubular occlusion and patency; however, although the association between occlusion and pain score was positive, this technique needs to be refined before use in future studies.