Glass ionomer cements (GIC) are dental restorative materials that are suitable for modification to help prevent dental plaque (biofilm) formation. The aim of this study was to determine the effects ...of incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a GIC on the colonisation and establishment of Streptococcus mutans biofilms and the effects of aqueous CPP-ACP on established S mutans biofilms. S. mutans biofilms were either established in flow cells before a single ten min exposure to 1% w/v CPP-ACP treatment or cultured in static wells or flow cells with either GIC or GIC containing 3% w/w CPP-ACP as the substratum. The biofilms were then visualised using confocal laser scanning microscopy after BacLight LIVE/DEAD staining. A significant decrease in biovolume and average thickness of S. mutans biofilms was observed in both static and flow cell assays when 3% CPP-ACP was incorporated into the GIC substratum. A single ten min treatment with aqueous 1% CPP-ACP resulted in a 58% decrease in biofilm biomass and thickness of established S. mutans biofilms grown in a flow cell. The treatment also significantly altered the structure of these biofilms compared with controls. The incorporation of 3% CPP-ACP into GIC significantly reduced S. mutans biofilm development indicating another potential anticariogenic mechanism of this material. Additionally aqueous CPP-ACP disrupted established S. mutans biofilms. The use of CPP-ACP containing GIC combined with regular CPP-ACP treatment may lower S. mutans challenge.
•· Resin-based ion-leaching-material, Cention-N, showed promising calcium release and calcium/phosphate recharge capacities.•· Cention-N released fluoride greater than some glass-ionomer-based ...materials and Activa-Restorative in water.•· Recharge of Zirconomer, Equia Forte, and Fuji-VIII with MI-varnish released fluoride that could inhibit caries initiation.•· Recharge using MI-Varnish immediately increased the hardness of ion-leaching-materials irrespective of the storage medium.
The objectives of this study were to evaluate fluoride (F), calcium (Ca), and phosphate (P) release of ion-leaching restorative materials (ILMs), their recharge efficacy with a Ca/P-containing F varnish, and relative microhardness.
Thirteen groups of materials were investigated. Cylindrical-shaped specimens were fabricated. Deionised water or lactic-acid solution were used as the storage media. Solutions were changed after 1d, 4d, 7d, and 14d of ion release and at the same periods after recharge with MI Varnish (7 -h storage). F, Ca, and P measurements were accomplished using a fluoride-ion selective electrode, atomic absorption spectrometry, and colourimetric method by spectrophotometer, respectively. Relative Vickers hardness was proceeded with similar specimens used in the F assay (4 periods). SEM/EDS was additionally performed. Statistical analyses were calculated in each parameter (p < 0.05).
Hardness of several ILMs immediately increased after recharge. After 28d, Ketac Universal a high-viscosity glass-ionomer cement (HVGIC) showed the highest hardness similar to the resin composite control. Although 2 HVGICs (Zirconomer and Equia Forte Fil) ranked as first and second for F release/re-release, some HVGICs had inferior or comparable F capacity to RMGICs (Fuji VIII and Fuji II LC) and a resin-based (RB) ILM (Cention N). Cention N, Activa-Restorative (RB-ILM), and Zirconomer were the top-3 ranking for Ca release/re-release. Activa-Restorative showed the highest P release, whereas Cention N displayed the greatest recharge ability for P.
Zirconomer showed a versatile performance for ion-release/re-release, especially for F. Cention N had excellent capacity in relation to Ca release and recharge ability of Ca/P.
With the F varnish recharge protocol, Zirconomer, Equia Forte, and Fuji VIII seems to have an ability to inhibit initial caries initiation. Cention N is a promising resin-based material that could be an alternative for high caries risk patients due to the high Ca release/recharge with acceptable F release.
To review the clinical performance of GIC restorations using calculated annual failure rates (AFRs) and qualitative descriptions based on conventional and ART techniques from two aspects: occlusal ...and approximal cavities in permanent or deciduous posterior teeth.
Search strategies were undertaken of the PubMed database from January 1983 to March 2018. Additional articles were collected by hand searching.
The following basic search terms, “(glass ionomer cement) and (clinical performance or survival or ART or atraumatic restorative or high viscosity)” with inclusion and exclusion criteria according to PRISMA flow diagram were used.
A total of 904 articles were initially identified. Finally, 67 articles were included for quantitative and qualitative analysis after applying the inclusion and exclusion criteria. Assessment of risk of bias was performed for all included studies using ROBINS-I.
For single-surface occlusal or multi-surface GIC restorations, the conventional technique showed better survival than ART technique regardless of dentition type (primary or permanent). When comparing the same treatment technique, AFRs of approximal or multi-surface GIC restorations were greater than those of single-surface (occlusal) restorations, irrespective of dentition type. RMGIC-conventional technique seems to be promising for restoring approximal cavities of primary teeth compared to other restorative materials.
The GIC-ART technique is an alternative option for single-surface (occlusal) restorations in permanent and primary teeth. However, the application of the GIC-ART technique for load-bearing approximal restorations should be carefully considered before employing this option, especially in primary teeth.
Background
Accurate implant impression is an essential requirement for the fabrication of implant prosthesis. This in vitro study evaluated the accuracy of digital impressions by intraoral scanner ...(IOS) systems in comparison to conventional impressions for recording the position of 2 parallel implants and 2 divergent implants.
Materials and methods
In vitro 3-unit prosthesis master models with 2 tissue level implants were fabricated; one model had parallel implants, and the other model had one 15° tilted implant. The conventional open-tray impressions were obtained with non-splinted (NSP) and splinted (SP) impression copings. Trios 4 (TS), Medit i500 (MT), and True Definition (TD) were used to make digital impressions with scan bodies. A total of 10 impressions were obtained with every technique. The virtual test images of the conventional and digital impressions were converted to 2 virtual implant images. For each group, trueness, precision, inter-implant distance deviation, and angle deviation were measured.
Results
There was a general tendency for digital impressions to provide a more accurate outcome for trueness, precision, and angle deviation. The 2 conventional impressions showed similar accuracy, except for the angle deviation, where the NSP was significantly inferior than SP (
p
< 0.01) for the divergent implants model. The TD was generally the least accurate among all the IOS systems, especially for the inter-implant distance deviation (
p
< 0.05).
Conclusions
Within the limitations of the laboratory set-up of the present study and the limited clinical resemblance, the digital impressions appeared to have sufficient accuracy for 2 implants and were least affected by the presence of angle between implants. The most inferior outcome was observed for the NSP technique.
Abstract Introduction The push-out test has been widely used in experimental endodontics but has been criticized on technical grounds particularly because the soft-core material undergoes plastic ...deformation under load. This study systematically evaluated the technique by comparing push-out strength and load profiles in relation to core material stiffness, canal diameter, punch diameter, sample orientation, and mode of failure. Methods Straight palatal roots of 90 maxillary molars were obturated with an epoxy resin–based sealer alone (10 roots) or gutta-percha (70) or epoxy resin (10) cores with a thin layer of sealer cement. Roots were embedded in mounting resin vertically or at an angle of 5° or 10° to the long axis of the root. One-millimeter sections were tested using a universal testing machine with a punch diameter corresponding to 50%, 75%, or 90% of the canal diameter. Bond strengths (MPa) were calculated, and data were analyzed using analysis of variance with post hoc Tukey multiple comparisons ( P < .05). After push out, core materials and canal walls were examined using scanning electron microscopy. Results Push-out strength was affected by core material stiffness. Angulation up to 10° from vertical had little effect on push-out strength, but load profiles were strongly influenced by orientation. No effect of the punch diameter was observed when the diameter was 90% of the canal diameter, but push-out strength was lower when the punch diameter was 50%–60% of the canal size. Conclusions Despite limitations, the push-out test may still be suitable for ranking the bonding of root filling materials.
Abstract Objectives To investigate and clarify physical and chemical properties of enamel affected by molar incisor hypomineralisation (MIH). Methods A series of in vitro studies were performed on ...extracted molars affected by MIH and sound teeth for controls. Tooth sections underwent Vickers microhardness testing before lapping and subsequent transverse microradiographic analysis and examination under polarised light microscopy. Carbonate content was determined by CO2 release from acid digestion. Unprepared and fractured surfaces were examined under scanning electron microscopy. Results MIH-affected molars demonstrated a severe degree of hypomineralisation with an average mineral content of only 58.8% vol% mineral. Vickers microhardness was significantly reduced in MIH compared with controls (1.8 ± 1.1 v 4.4 ± 1.0 GPa, p < 0.05) and polarised light microscopy revealed the bulk of MIH lesions had a porosity of ≤5% but also substantial areas of ≥10% and smaller areas exceeding 25% porosity. A surface layer was frequently observed on both intact and broken-down lesions and cervical regions of MIH teeth were typically spared. Carbonate content of MIH enamel was higher than control samples (6.6 ± 2.1 v 4.4 ± 1.1 wt%, p < 0.05). Scanning electron microscopy showed that both the enamel rod and surface ultrastructure were defective. Clinical characteristics did not consistently correlate with all properties. Conclusions The properties of MIH-affected enamel significantly differ from those of normal enamel and were highly variable, however some common characteristics were observed. Implications for aetiology and clinical management are discussed.
•Different calcium phosphate additives in F varnishes have distinct remineralising efficacy.•Combined use of F varnishes with 5000 ppm F toothpastes improved remineralisation.•Proanthocyanidin as an ...adjunct to F regimens improved remineralisation in dentine subsurface.•Increased mineral density was not necessarily translated into improved hardness of dentine.
To evaluate the remineralising effects of fluoride (F) varnishes containing bioavailable calcium-phosphate compound (Ca-P) based remineralisation systems and 5000 ppm F toothpaste (FTP) on root caries lesions (RCLs) and the potential effects of proanthocyanidin (PA) for the treatments of RCLs when used as an adjunct to F regimens.
Demineralised root dentine and a pH-cycling model were used to mimic RCLs and the oral environment. Remineralising effects of MI VarnishTM (MIV) containing casein phosphopeptide–amorphous calcium phosphate (CPP-ACP) and Clinpro™ White Varnish (CPWV) containing tri-calcium phosphate (TCP) along with FTP and PA were evaluated regarding the birefringence, elemental composition, mechanical properties and mineral density of remineralised dentine with DuraphatTM as a comparison.
MIV, CPWV and DuraphatTM promoted the incorporation of F into RCLs and increased mineral density but did not change microhardness of root dentine significantly. Surface microhardness increased significantly when MIV or CPWV was used with 5000 ppm FTP. Application of PA with F regimens significantly increased subsurface mineral density. When PA was applied with MIV or CPWV along with FTP, the highest ion uptake and relative mineral gain (%ΔZ) was achieved, and significant increase of microhardness was up to 30 μm depth. Generally, MIV was associated with a higher mineral content gain than CPWV.
Treatment of carious root surfaces remains challenging due to the complex pathological processes and difficulty in restoring the highly organised structure of root dentine. Treatment strategies targeting both remineralisation and preservation of the dentinal organic matrix have the potential to improve the fluoride-mediated remineralisation approaches.
Objective
A novel implant design, the rectangular block implant (RBI), was investigated as a possible solution to the restoration of the posterior resorbed ridge.
Aim
To maximally load test the ...osseo‐integrated RBI in shear and tensile loads and relate these findings to known human masticatory loads as biomechanical proof of the study concept.
Materials and methods
Twelve RBIs were design‐manufactured and placed into posterior mandibular saddles in 3 mature greyhound dogs.—2 per left and right. After 12 weeks of healing, osseo‐integration was confirmed using resonance frequency analysis (RFA) and wrench torque tests. Three bone blocks each with two RBIs were dissected and mounted in acrylic. Micro‐computerized tomography (μ‐CT) was performed to assess bone to implant contact (BIC), and load analysis was performed using a Universal Test System. Three force applications were conducted until failure: pull‐out (tensile), buccal push from the lingual (shear) and distal push from the mesial (shear). The osteotomy sites were examined using light magnification and scanning electron microscopy (SEM).
Results
Pull‐out, buccal and distal force failures occurred at differing levels. Post‐detachment sites showed complex patterns of bone failure, including trabecular and cortical fracture, as well as shearing at varying distances from the BIC. Interfacial shear strength was calculated at 14.4 MPa.
Conclusion
The osseo‐integrated RBIs were able to withstand simulations of the demanding axially, bucco‐lingually and mesio‐distally oriented biomechanical challenges of the posterior saddle, under conditions of reduced bone volume. These values exceeded equivalent force components of maximal masticatory loads in humans.
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Treatment of carious root surfaces remains challenging due to the complex pathological processes and difficulty in restoring the original structure of root dentine. Current treatments ...targeting the de-/re-mineralisation processes are not entirely satisfactory in terms of the protection of the dentinal organic matrix and the highly organised structure of dentine. In this in vitro study, a cross-linking agent – proanthocyanidin (PA) was used in conjunction with a fluoride-based treatment – silver diamine fluoride/potassium iodide (SDF/KI) to putatively stabilise the organic dentinal framework as well as strengthen the collagen-mineral phase interaction. The effectiveness of this strategy was evaluated 24 h after application in terms of the distribution of ion uptake and microstructure of dentine after treatment as well as analysis of the nano-mechanical properties using a dynamic behaviour model. Results showed that individual use of SDF/KI significantly improved the surface microhardness and integrated mineral density (Z) up to 60 µm depth and the recovery of creep behaviour of demineralised dentine in the surface area compared to that treated with deionised distilled water (DDW). The combined treatment of PA and SDF/KI achieved a more homogenous mineral distribution throughout the lesions than SDF/KI alone; a more significant incremental increase in surface microhardness and Z was observed. Specifically, a superior effect on the subsurface area occurred with PA + SDF/KI, with significant improvements in microhardness, elastic modulus and recovery of creep behaviour of the demineralised dentine. Application of SDF/KI induced small discrete crystal formation distributed over the dentine surface and PA contributed to the formation of slit-shaped orifices of the dentinal tubules that were partially occluded.
Demographic transitions and improved oral health behaviour have resulted in increased tooth retention in elderly people. As a consequence, the risk of root dentine caries is increasing due to the age-associated gingival recession and the related frequent exposure of cervical root dentine. Root caries is difficult to repair because of the complex aetiology and dentine structure. The recovery of dentine quality depends not only on reincorporation of minerals but also an intact dentinal organic matrix and the organic-inorganic interfacial structure, which contribute to the biomechanics of dentine. With the capability of dentine modification, cross-linking agents were applied with a fluoride regimen, which improved its treatment efficacy of root caries regarding the distribution of ion uptake and recovery of dentine biomechanics.
This study compared the fracture toughness values of seven resin composites and analyzed the consistency of data values using three methods: compact tension, three point and four point bending for ...Mode I failure. Seven resin composites were selected: Estellite Sigma Quick, Esthet X HD, Filtek Supreme XTE, Heliomolar, Ice, Rok, and Vit-l-escence. For each material, 18 specimens (n=6 for each test) were prepared. Maximum load to failure was recorded using a universal testing machine and fracture toughness was calculated. There was a direct significant correlation among all tested methods. Rok showed the highest and Estelite the lowest KIc values. SEM of the fractured surface of compact tension method showed propagation of the cracks from stresses concentrating at the corner of the notch and the surface of the sample. Four-point test gave the largest range in KIc and was a simple method to discriminate between the resin composite values of KIc.
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