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Abstract Background This study aimed to investigate the effects of different ferrule heights and crown-to-root ratios on the fracture resistance of endodontically-treated premolars restored with fiber post or cast metal post system. Methods Eighty extracted human mandibular first premolars with single root canal were treated endodontically and cut from 2.0 mm above the buccal cemento-enamel junction, to create horizontal residual roots. The roots were randomly divided into two groups. The roots in group FP were restored with a fiber post-and-core system, while the roots in group MP were restored with a cast metal post-and-core system. Each group was divided into five subgroups with different ferrule heights (0: no ferrule; 1: 1.0 mm ferrule; 2: 2.0 mm ferrule; 3: 3.0 mm ferrule; 4: 4.0 mm ferrule). All specimens were subsequently restored with metal crowns and embedded in acrylic resin blocks. The crown-to-root ratios of the specimens were controlled at approximately 0.6, 0.8, 0.9, 1.1, and 1.3 of the five subgroups, respectively. Fracture strengths and fracture patterns of the specimens were tested and recorded by a universal mechanical machine. Results Mean fracture strengths (mean ± standard deviation (kN)) of FP/0 to FP/4 and MP/0 to MP/4 were: 0.54 ± 0.09, 1.03 ± 0.11, 1.06 ± 0.17, 0.85 ± 0.11; 0.57 ± 0.10, 0.55 ± 0.09, 0.88 ± 0.13, 1.08 ± 0.17, 1.05 ± 0.18 and 0.49 ± 0.09, respectively. Two-way ANOVA revealed significant effects of different ferrule heights and crown-to-root ratios on the fracture resistance (P

Abstract Backgroud Root caries in aging population was prevalent worldwide. Due to the absence of enamel and specific structure of dentine, bacteria are able to penetrate further into dentine at an earlier stage of lesion development. The aim of this study was to investigate the effect of adding of a strontium-doped bioactive glass-ceramic (HX-BGC) to a fluoride-free toothpaste on prevention of formation of artificial dentine caries. Methods Thirty-six human tooth specimens were allocated to three groups (n = 12 per group). Group 1 treated with slurry containing a fluoride-free toothpaste and 5% HX-BGC, Group 2 was treated with fluoride-free toothpaste slurry, and Group 3 received deionized water as a negative control. The specimens were subjected to four cycles (15 h demineralization and 8 h remineralization for one cycle) of biochemical cycling. A mixed suspension of five bacteria species (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus, Lactobacillus rhamnosus, and Actinomyces naeslundii) were prepared in brain heart infusion broth with 5% sucrose and used as acidic challenge in biochemical cycling. Subsequently, surface morphology of the dentine lesion was assessed by scanning electron microscopy, while the lesion depths and mineral loss were assessed by micro-computed tomography. Results The mean lesion depths in dentine in Groups 1 to 3 were 87.79 ± 16.99 μm, 101.06 ± 10.04 μm and 113.60 ± 16.36 μm, respectively (p = 0.002). The mean amounts of mineral loss in Groups 1 to 3 were 0.82 ± 0.10 g/cm3, 0.89 ± 0.09 g/cm3 and 0.96 ± 0.11 g/cm3, respectively (p = 0.016). No obvious differences in the surface morphology were seen among the groups. Conclusion Addition of strontium-doped bioactive glass-ceramic to fluoride-free toothpaste has potential to reduce formation of dentine lesions.

Abstract Background Silver diamine fluoride (SDF) solution gains increasing popularity in arresting dentine caries in clinical practice. The aim of this systematic review was to summarize the findings from laboratory studies on the influence of SDF application on the bond strength of dentine to various adhesives and to glass ionomer cements (GICs). Methods Two independent reviewers conducted a literature search in the databases Medline, Ovid, PubMed and Web of Science until 15th August 2019 using the search keywords [‘bond strength’] AND [‘silver diamine fluoride’ OR ‘silver diammine fluoride’ OR ‘SDF’ OR ‘silver fluoride’ OR ‘diamine silver fluoride’]. Articles investigating the effect of SDF application on the bond strength of dentine to various adhesives and to GICs were included in this review. Information on how SDF application influenced the bond strength was extracted from the included articles. Besides, related information, e.g. test method of bond strength, concentration and brand of SDF, type of adhesive system and GIC, testing dental substrate, protocol of specimen preparation, and failure mode was also reviewed. Results A total of 13 articles were included in this review, with 8 and 6 studies investigating the effect of SDF application on the bond strength of dentine to various adhesives and to GICs, respectively. Sound dentine as well as demineralized dentine created by chemical methods, e.g. immersing in a demineralizing solution, was commonly adopted as the testing dental substrate. The microtensile bond strength (mTBS) test was the predominant method employed. However, the bond strength values had large variations among studies, ranging from

Abstract Background This study investigated the remineralisation effect of bioactive glass on artificial dentine caries. Methods Dentine disks with artificial caries were treated with bioactive glass (group BAG), casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) (group CPP-ACP), sodium fluoride glycerol (group F) or deionized water (group W). All disks were subjected to pH cycling for 28 days subsequently. The topography, microhardness and remineralisation depth of the dentine carious lesion were assessed by atomic force microscopy (AFM), microhardness testing and confocal laser scanning microscope (CLSM), respectively. Results AFM images indicated mineral depositions on the surface of the carious lesion in group BAG. The changes of Vickers hardness number (ΔVHN, mean ± SD) after pH cycling were 9.67 ± 3.60, 6.06 ± 3.83, 5.00 ± 2.19 and − 1.90 ± 2.09 (p