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1.
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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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.
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Does the Orifice-directed Dentin Conservation Access Design Debride Pulp Chamber and Mesial Root Canal Systems of Mandibular Molars Similar to a Traditional Access Design?
Neelakantan, P, Khan, K, Hei Ng, GP, Yip, CY, Zhang, C, Pan Cheung, GS
Journal of endodontics. 2018;(2):274-279
Abstract
INTRODUCTION Despite the increasing reports on mechanical aspects of contracted endodontic access cavities (CECs), we believe that the biological aspects (debridement) have not been adequately investigated. This study examined if 1 type of CEC (orifice-directed dentin conservation [DDC] access) was able to debride the pulp chamber, root canals, and isthmus of mesial roots of mandibular molars similar to a traditional endodontic access cavity (TEC). METHODS Mandibular molars (N = 32) were selected and divided randomly into 2 experimental groups (n = 12) after micro-computed tomographic scanning (group 1: TEC and group 2: DDC) and histologic controls (n = 8). After instrumentation to a size 30/0.06 taper using 3% sodium hypochlorite as irrigant, specimens were processed for histologic evaluation, and the remaining pulp tissue (RPT) was measured from the pulp chamber, root canal, and isthmus at all root thirds. Data were analyzed using 1-way analysis of variance, Kruskal-Wallis, and appropriate post hoc tests (P = .05). RESULTS The RPT in the pulp chamber was significantly higher in DDC compared with TEC (P < .05). Comparing the root thirds in each group, there was no significant difference in the RPT within the root canals or the isthmus (P > .05). The RPT within the root canals and isthmus was not significantly different between the 2 access cavity designs at any root third (P > .05). CONCLUSIONS Debridement of the pulp chamber was significantly compromised in DDC. The type of access cavity did not influence the amount of RPT in the root canals and isthmus.
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Effect of the concentration of water in an MDP-based all-in-one adhesive on the efficacy of smear layer removal and on dentin bonding performance.
Teshima, M
Dental materials journal. 2018;(4):685-692
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The effects of the water concentration in an experimental 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based all-in-one (EX) adhesive were examined on the ability of MDP to remove the smear layer from the ground dentin surface and on the dentin bonding performance. Four types of EX adhesives were prepared by varying the amount of water (46.6, 93.2, 149.8 and 208.1 mg/g), but the MDP concentration was kept a constant at 49.9 mg/g. Scanning electron microscopy and bond strength measurements were performed on the dentin surface demineralized by each EX adhesive. Increased amount of water in the EX adhesive increased the ability of MDP to remove the smear layer. However, the solubilization of the smear layer into the EX adhesive decreased the dentin bond strength. The water concentration in the EX adhesive affected the efficacies of smear layer removal and dentin bonding performance more strongly than the pH value of the EX adhesive.
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Effect of Low-surface Tension EDTA Solutions on the Bond Strength of Resin-based Sealer to Young and Old Root Canal Dentin.
Güzel, C, Uzunoglu, E, Dogan Buzoglu, H
Journal of endodontics. 2018;(3):485-488
Abstract
INTRODUCTION The purpose of this study was to evaluate the effect of low-surface tension EDTA solutions on the push-out bond strength of resin-based sealer to young and old root canal dentin. METHODS Root canals from 64 (n = 32 age <30 years old and n = 32 >60 years old) extracted, decoronized, single-rooted human teeth were prepared with ProTaper rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) up to size F4 using 3 mL 2.5% sodium hypochlorite (NaOCl) between each file. Each group was divided into 4 subgroups as follows: 3 mL EDTA, REDTA (17% EDTA + 0.84 g cetyltrimethylammonium bromide; Sigma-Aldrich, St Louis, MO), EDTA-T (17% EDTA + 1.25% sodium lauryl ether sulfate, Sigma-Aldrich), and saline as the control (n = 8). The final irrigation was completed with 3 mL saline after 3 mL NaOCl in the experimental groups and 3 mL saline in the control group. After root canal filling with gutta-percha (GP) cones/AH Plus sealer (Dentsply, Petropolis, RJ, Brazil), samples were stored at 37°C and 100% humidity for 2 weeks. One-millimeter-thick horizontal sections from the coronal and midthirds of each root were sliced, and push-out bond strength values were measured using a universal testing machine. Data were analyzed using 2-way analysis of variance followed by the Bonferroni test (P < .05). RESULTS EDTA-T, REDTA, and EDTA significantly increased the bond strength values of GP/AH Plus to the root canal dentin compared with saline in both young and old groups (P < .05). EDTA-T treatment provided higher bond strength values in young dentin compared with EDTA and EDTA-T-treated old dentin (P < .05). CONCLUSIONS The bond strength values of GP/AH Plus could be altered depending on age and the type of EDTA compounds.
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The In Situ Effect of Titanium Tetrafluoride Gel on Erosion/Abrasion Progression in Human Dentin.
Mantilla, TF, Turssi, CP, Ramos-Oliveira, TM, Silva, CVD, Suzuki, LC, Freitas, PM
Brazilian dental journal. 2017;(3):337-345
Abstract
Erosion incidence is increasing and its control is still a challenge in clinical practice. This study evaluated 4% TiF4-gel effects on eroded human dentin subjected to in situ erosive/abrasive episodes. Seventy-two previously eroded dentin slabs (0.05 M citric acid, pH 2.3, 20 min) were allocated to 6 groups (n=12) according to the treatment to be performed during the in situ phase and number of erosive/abrasive cycles, as follows: 4% TiF4-gel applied once (TiF41), twice (TiF42) or three times (TiF43) followed by 1, 2 and 3 erosive/abrasive cycles, respectively. Gel was applied before the beginning of the next cycle. Control groups were subjected to 1 (C1), 2 (C2) and 3 (C3) erosive/abrasive cycles only. A seventh group (n=12) comprised in vitro uneroded samples (UN) subjected to 3 erosive/abrasive cycles. Each cycle corresponded to 2 days of erosive (citric acid 0.5%, pH 2.6, 6x/day) and abrasive (electric toothbrush, 10 s/sample, 1 x/day) challenges. Samples were evaluated under profilometry and environmental scanning electron microscopy (ESEM). Atomic force microscopy images (AFM) were also made (n=3). Repeated measures 2-way ANOVA and Tukey test (p<0.001) showed that TiF42, which did not differ from TiF41 and TiF43, revealed a significant reduction in surface loss compared to all control groups. TiF41 and TiF43 showed no significant difference from C1, but both groups demonstrated significantly smaller surface loss than C2 and C3. ESEM and AFM micrographs suggested alterations on treated surfaces compared to samples from control groups, showing reduced diameters of dentinal tubules lumens. Therefore, TiF4 was able to reduce the progression of erosive/abrasive lesions.