Comparison of natural and artificial root caries lesions using microcomputed tomography and microhardness test.

BACKGROUND: This study compared natural root caries lesions with artificial root caries lesions prepared with one of the two demineralising solutions. METHODS: Twelve natural root caries lesions on upper incisors and 24 artificial root lesions were prepared on sound root surfaces using 50 mM acetic acid, 1.5 mM CaCl2 , 0.9 mM KH2 PO4 at pH 5.0 or 80 mL/L Noverite K-702 polyacrylate solution, 500 mg/L hydroxyapatite, 0.1 mol/L lactic acid at pH 4.8 (n = 12/group) for 96 hours. Lesions were scanned using micro-CT. Inciso-gingival oriented images were analysed and mineral density calculated at 7.5 µm increments from the surface to 225-µm deep. Sectioned lesions were analysed by Knoop microhardness up to 250 µm from the lesion surface. Data were analysed by the Dunn's test with Bonferroni correction. RESULTS: Natural and artificial lesion mean mineral densities were not statistically different (P > 0.05). Mineral density from the surface to 75 µm was greater in natural lesions and from 150 to 225 µm was greater in artificial lesions (P < 0.05). Microhardness values were statistically higher in artificial lesions (P < 0.05); no difference was found among artificial lesions produced by the two solutions (P > 0.05). Mineral density and microhardness of natural and artificial root caries are different from each other. A greater mineralized surface layer existed on natural lesions.

Biological considerations of dental materials as orifice barriers for restoring root-filled teeth.

There is ample published literature regarding the technical aspects of restoring root-filled teeth, but little concerning the biological impacts, consequences, and criteria for the selection of direct restorative materials following endodontic treatment. The provision of an effective coronal seal in addition to a sound root filling is known to be important in the prevention of root canal infection. This review seeks to explore the evidence concerning the selection of dental materials in the restoration of root-filled teeth, specifically with a close examination of the properties of commonly used materials as orifice barriers. © 2023 Australian Dental Association.

Effect of CPP-ACP modified-GIC on prevention of demineralization in comparison to other fluoride-containing restorative materials.

BACKGROUND: This study evaluated the ability of a CPP-ACP-modified Glass-ionomer cement (GIC) to inhibit demineralization around the margins of cervical cavities in natural teeth in comparison with a Giomer and conventional GIC with and without coating. METHODS: Thirty-two sound human molars were used. Box-shaped cavities were prepared along the CEJ. Teeth were randomly divided into four groups and restored with Equia Forte Fil, Coated Equia Forte Fil, Fuji VII EP or Beautifil II. Teeth were subjected to pH cycling. Micromorphological and elemental analyses were done using SEM and EDX. Polarized light microscope analysis and microhardness tests were also performed. RESULTS: Microhardness tests on enamel showed a significant difference between the coated Equia group, Equia and Beautifil II groups (P < 0.05). Dentine results showed significant differences between the coated Equia group and all other groups (P < 0.05). Elemental analysis showed significant differences in calcium weight percentage among the first and second observation levels in all groups (P < 0.05). A significant difference was found between the coated Equia group and the other three groups (P < 0.05). CONCLUSIONS: All tested materials showed some ability to resist demineralization at the restoration margins. The coated GIC restoration showed better outcomes compared with the other tested materials.

Status and progress of treatment methods for root caries in the last decade: a literature review.

The aim of this literature review is to explore the treatment methods for root caries in laboratory and clinical research in the last decade. A systematic search of publications in PubMed and Web of Science databases was performed. The timespan was limited to the last 10 years and English language. Further retrieval was conducted using the search terms of specific therapies or treatments. Eighty-two articles were included in this systematic review and full texts were retrieved. Types of studies included laboratory studies and clinical trials. Therapeutic approaches for root caries without risk of pulp exposure can be categorized into non-invasive and restorative treatment. Non-invasive treatments which targeted different causative factors of root caries have been developed in the last decade. Accordingly, several artificial caries model systems have been proposed for the study of root caries in the laboratory. Carious tissue excavation techniques and restorative materials and procedures have been modified to improve the prognosis of invasive treatment. It is of importance to determine the most appropriate therapy for root caries and further clinical trials are needed to draw firm conclusions concerning the efficacy and consistency of the various treatment methods proposed.

Effect of a self-adhesive coating on the load-bearing capacity of tooth-coloured restorative materials.

BACKGROUND: The aim of this study was to compare the flexural strength and Vickers hardness of tooth-coloured restorative materials with and without applying a self-adhesive coating for up to 6 months. METHODS: Specimens were prepared from three resin composites (RC), two resin-modified glass-ionomer cements (RM-GIC) and two conventional glass-ionomer cements (CGIC). All materials were tested both with and without applying G-Coat Plus (GCP). Specimens were conditioned in 37 °C distilled deionized water for 24 h, and 1, 3 and 6 months. The specimens were strength tested using a four-point bend test jig in a universal testing machine. The broken specimen's halves were used for Vickers hardness testing. Representative specimens were examined under an environmental scanning electron microscope. RESULTS: Data analysis showed that regardless of time and materials, generally the surface coating was associated with a significant increase in the flexural strength of the materials. Applying the GCP decreased the hardness of almost all materials significantly (P < 0.05) and effect of time intervals on hardness was material dependent. CONCLUSIONS: The load-bearing capacity of the restorative materials was affected by applying self-adhesive coating and ageing. The CGIC had significantly higher hardness but lower flexural strength than the RM-GIC and RC.

The physical properties and ion release of CPP-ACP-modified calcium silicate-based cements.

BACKGROUND: This study investigated the physical properties and ion release of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified calcium silicate-based cements (CSCs) and compared the properties of a trial mineral trioxide aggregate (MTA) with two commercially available CSCs, Biodentine(™) and Angelus(®) MTA. METHODS: The setting time, solubility, compressive strength and Vickers surface microhardness of the three CSCs incorporated with 0%, 0.5%, 1.0%, 2.0% and 3.0% (w/w) CPP-ACP were investigated. Release of calcium (Ca(2+) ), phosphate ions (Pi ) and pH of the test cements were measured after 24, 72, 168 and 336 h of storage. RESULTS: The addition of up to 1.0% CPP-ACP into Biodentine(™) and 0.5% into the other cements did not adversely affect their physical properties except for the setting time. The addition of 0.5% CPP-ACP increased Ca(2+) released from Biodentine(™) (after 168 and 336 h), Angelus(®) MTA (after 168 h) and the trial MTA (after 72 h). The addition of 1.0-3.0% CPP-ACP increased Ca(2+) and Pi released from all the cements. Biodentine(™) released more Ca(2+) particularly in the early stages and showed shorter setting time and higher mechanical properties than the other cements. The mechanical properties of Angelus(®) MTA and the trial MTA were similar. All the cements produced highly alkaline storage solutions. CONCLUSIONS: Up to 1.0% CPP-ACP in Biodentine(™) improves Ca(2+) and Pi release and 0.5% CPP-ACP in Angelus(®) MTA and the trial MTA improves Ca(2+) release without altering the mechanical properties and solubility. The addition of CPP-ACP into CSCs prolonged the setting time.