-
Australian Endodontic Journal : the... Dec 2023The aim of the study was to evaluate the influence of resin cement material types on tooth with endocrown and onlay restorations. The first molar was scanned using...
The aim of the study was to evaluate the influence of resin cement material types on tooth with endocrown and onlay restorations. The first molar was scanned using Micro-CT and underwent a modelling process to obtain the 3D model for computational simulation. Eight models were simulated in the current study with two loading conditions (720N vertical load and 200N oblique load), two types of restoration (onlay and endocrown restorations), and two resin cement variants (dual-cure resin cement and light-cure resin cement). The tooth with onlay restoration showed a significant stress reduction (up to 70%) when using light-cure resin cement compared to dual-cure resin cement. In contrast, types of cement did not affect stress distribution in the tooth with endocrown restoration. The current study found that dual-cure resin cement was preferable in Endocrown and Onlay restorations, due to dual-cure resin cement provided better bond strength compared to light-cure resin cement.
Topics: Crowns; Resin Cements; Finite Element Analysis; Dental Stress Analysis; Inlays; Materials Testing; Composite Resins
PubMed: 37789568
DOI: 10.1111/aej.12800 -
Journal of Biomedical Materials... Jan 2024The use of glass-ceramics in the medical field has grown significantly since the 1980s. With excellent aesthetic properties, semi-translucency, outstanding mechanical... (Review)
Review
The use of glass-ceramics in the medical field has grown significantly since the 1980s. With excellent aesthetic properties, semi-translucency, outstanding mechanical properties, corrosion resistance, wear resistance and great biocompatibility and workability glass-ceramics is one of the most commonly used materials in restorative dentistry and is widely used in veneers, inlays, onlays, all-ceramic crowns, and implant abutments. This review provides an overview of the research progress of glass-ceramics in restorative dentistry, focusing on the classification, performance requirements, toughening mechanisms and their association with clinical performance, as well as the manufacturing and fabrication of glass-ceramics in restorative dentistry. Finally, the developments and prospects of glass-ceramics in restorative dentistry are summarized and discussed.
Topics: Dentistry; Ceramics; Dental Porcelain; Materials Testing
PubMed: 37776023
DOI: 10.1002/jbm.b.35334 -
Journal of Functional Biomaterials Sep 2023Dental ceramics are susceptible to slow, progressive crack growth after cyclic loading. The purpose of this study was to investigate the progressive patterns of cracks...
Dental ceramics are susceptible to slow, progressive crack growth after cyclic loading. The purpose of this study was to investigate the progressive patterns of cracks in two different types of CAD/CAM ceramic materials used with three different partial posterior indirect restoration (PPIR) designs and to determine the materials' failure risk using a fatigue test. Standard initial cracks were formed in Standard Tessellation Language (STL) files prepared for three different PPIRs. The materials chosen were monolithic lithium disilicate (LS) and polymer-infiltrated ceramic networks (PICNs). The extended finite element method (XFEM) was applied, and the fatigue performance was examined by applying a 600 N axial load. The cracks propagated the most in onlay restorations, where the highest displacement was observed. In contrast, the most successful results were observed in overlay restorations. Overlay restorations also showed better fatigue performance. LS materials exhibited more successful results than PICN materials. LS materials, which can be used in PPIRs, yield better results compared to PICN materials. While inlay restorations demonstrated relatively successful results, overlay and onlay restorations can be specified as the most and the least successful PPIR types, respectively.
PubMed: 37754898
DOI: 10.3390/jfb14090484 -
Journal of Esthetic and Restorative... Apr 2024The development of dental adhesives with enhanced bond strength has assisted minimally invasive dentistry. The aim of this study was to evaluate the fracture load and...
OBJECTIVES
The development of dental adhesives with enhanced bond strength has assisted minimally invasive dentistry. The aim of this study was to evaluate the fracture load and stress distribution pattern of two retainer designs for posterior cantilever resin bonded fixed dental protheses (RBFDPs).
MATERIALS AND METHODS
Forty human mandibular molars were divided into two groups according to the retainer design; lingual coverage (LC) and occlusal coverage (OC) retainers. Each main group was then divided according to the number of inlay boxes (n = 10); one inlay and two inlay boxes. High translucency (3Y) zirconia was used to manufacture all restorations, and a dual-polymerizing adhesive resin cement was used for bonding. All specimens underwent 10,000 cycles of thermocycling (5-55°C), 240,000 cycles of dynamic loading (50 N, descending speed v = 30 mm/second, frequency = 1.6 Hz), and failure load test. Both one-way and two-way ANOVA tests were used to analyze the data. The four models included in the in-vitro study are part of the finite element analysis (FEA). When the restorations failed, maximal principal stress values on restorations, enamel, dentin, and luting resin were investigated.
RESULTS
A statistically significant (p = 0.018) higher failure load was recorded for OC1 (627.00 ± 153.4 N) than the other groups; (548.0 ± 75.6 N, 521.20 ± 11.3 N, and 509.20 ± 14.9 N for LC1, LC2, and OC2, respectively). With regard to failure mode, one inlay box designs showed more favorable failure pattern than those of two inlay boxes. FEA showed higher stress magnitude transmitted to the tooth structure in models LC2 and OC2.
CONCLUSIONS
Lingual coverage and occlusal coverage retainers are promising designs capable to withstand the normal occlusal force for cantilever RBFDP in premolar area. The use of two inlay boxes decreased the fracture load of the two retainer designs and increased the stress transmitted to the tooth and resulted in high incidence of catastrophic failure.
CLINICAL SIGNIFICANCE
Monolithic high translucent zirconia RBFDP could be considered as a viable treatment option to substitute missing posterior tooth, with improved esthetics and biocompatibility.
Topics: Humans; Inlays; Dental Bonding; Zirconium; Bicuspid; Resin Cements; Dental Stress Analysis; Dental Restoration Failure; Materials Testing
PubMed: 37737460
DOI: 10.1111/jerd.13130 -
Physics in Medicine and Biology Oct 2023To present an innovative approach for the design of a 3D mammographic phantom for medical equipment quality assessment, estimation of the glandular tissue percentage in...
To present an innovative approach for the design of a 3D mammographic phantom for medical equipment quality assessment, estimation of the glandular tissue percentage in the patient's breast, and emulation of microcalcification (C) breast lesions.Contrast-to noise ratio (CNR) measurements, as well as spatial resolution and intensity-to-glandularity calibrations under mammography conditions were performed to assess the effectiveness of the phantom. CNR measurements were applied to different groups of calcium hydroxyapatite (HA) and aluminum oxide (AO)Cs ranging from 200 to 600m. Spatial resolution was characterized using an aluminum plate contained in the phantom and standard linear figures of merit, such as the line spread function and modulation transfer function (MTF). The intensity-to-glandularity calibration was developed using an x-ray attenuation matrix within the phantom to estimate the glandular tissue percentage in a breast with a compressed thickness of 4 cm.For the prototype studied, the minimum confidence level for detecting HACs is 95.4%, while for AOCs is above 68.3%. It was also possible to determine that the MTF of the commercial mammography machine used for this study at the Nyquist frequency is 41%. Additionally, a one-to-one intensity-to-glandularity calibration was obtained and verified with Monte-Carlo simulation results.The phantom provides traditional arrangements presented in accreditation phantoms, which makes it competitive with available devices, but excelling in regarding affordability, modularity, and inlays distribution. Moreover, its design allows to be positioned in close proximity to the patient's breast during a medical screening for a simultaneous x-ray imaging, such that the features of the phantom can be used as reference values to specify characteristics of the real breast tissue, such as proportion of glandular/adipose composition and/orC type and size lesions.
Topics: Humans; Mammography; Breast; Computer Simulation; Phantoms, Imaging; X-Rays
PubMed: 37733054
DOI: 10.1088/1361-6560/acfc10 -
The Journal of Prosthetic Dentistry Sep 2023A consensus on whether a fully digital workflow can replace conventional methods of manufacturing partial-coverage restorations is lacking. (Review)
Review
STATEMENT OF PROBLEM
A consensus on whether a fully digital workflow can replace conventional methods of manufacturing partial-coverage restorations is lacking.
PURPOSE
The purpose of this systematic review was to evaluate the accuracy, fit, and clinical outcomes of inlay, onlay, overlay, and endocrown restorations obtained with both digital and conventional workflows.
MATERIAL AND METHODS
This study complied with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered in the International Prospective Register of Systematic Reviews database (CRD42021258696). Studies evaluating the accuracy, fit, and clinical outcomes of inlay, onlay, overlay, and endocrown restorations obtained with digital and conventional workflows were included from 5 databases searched in November 2022. The Checklist for Reporting Randomized Clinical Studies (ROB 2) and the Checklist for Reporting In vitro Studies (CRIS guidelines) were used to assess the risk of bias.
RESULTS
Twenty-three studies were included in this review. Sixteen studies evaluated marginal and internal fit, 5 evaluated accuracy, 3 evaluated fracture resistance, and 1 evaluated long-term clinical performance. Although most studies reported acceptable clinical outcomes for both workflows, 11 studies showed better results with the conventional workflow, 10 with the digital workflow, and 2 reported that the outcomes of the workflows were similar.
CONCLUSIONS
Clinically acceptable values have been reported for the parameters evaluated in both digital and conventional workflows, and no consensus has been reached regarding the more efficient method.
PubMed: 37716898
DOI: 10.1016/j.prosdent.2023.08.005 -
Polymers Aug 2023The thinking about metallic replacement has begun in a global context of reducing metallic alloys' use in odontology. Among the materials proposed for their replacement,...
The thinking about metallic replacement has begun in a global context of reducing metallic alloys' use in odontology. Among the materials proposed for their replacement, poly(etheretherketone) may present interesting properties, especially in removable dentures' frames. The purpose of this study is to evaluate fracture resistance of PEEK posts-and-cores compared to non-metallic CAD/CAM materials and fiber glass posts. Forty extracted maxillary central incisors were prepared to receive posts. Samples were divided into four groups depending on whether they had been reconstructed with LuxaCam PEEK, Enamic, Numerys GF or LuxaPost. Samples were submitted to an oblique compressive test and results were statistically analyzed with ANOVA and Student's tests (or non-parametric tests depending on the conditions). Glass fiber posts and Numerys GF reveal a significantly higher fracture resistance than LuxaCam PEEK and Enamic. No exclusively dental fracture has been noted for the Enamic group, which significantly distinguishes these samples from the three other groups. In our study, it appears that the conception of posts and cores with hybrid ceramic never conducts to a unique tooth fracture. By weighting the results according to the materials used, our data, obtained for the first time on this type of PEEK block, cannot confirm the possibility of using PEEK for inlay-core conception, excepted for specific cases when the material is considered in a patient presenting allergies or systemic disease contraindicating resin or metal.
PubMed: 37688208
DOI: 10.3390/polym15173583 -
Materials (Basel, Switzerland) Aug 2023Pathological tooth wear is an escalating social problem. Occlusal veneers can be an alternative to traditional prosthetic restorations such as crowns, inlays, and onlays.
UNLABELLED
Pathological tooth wear is an escalating social problem. Occlusal veneers can be an alternative to traditional prosthetic restorations such as crowns, inlays, and onlays.
BACKGROUND
The aim of this study is to assess the fracture resistance of occlusal veneers made of various materials depending on their thickness.
METHODS
In total, 120 occlusal veneers were examined. The restorations were made of four ceramics: leucite LC (IPS Empress Esthetic), hybrid HC (Vita Enamic), lithium disilicate LDC (IPS e.max Press), and zirconium oxide ZOC (Ceramill Zolid HT). A total of 30 veneers were made of each material, 10 for each of the three thicknesses: 1 mm, 1.5 mm, 2 mm. The restorations were cemented on identical abutments duplicated from the developed phantom tooth 35 (KaVo) with composite cement (All Bond Universal). The samples prepared in this way were subjected to a compressive strength test in a universal testing machine. Statistical analysis of the results was performed.
RESULTS
The average fracture resistance of occlusal veneers made of zirconium oxide ceramic was 1086-1640 N, of lithium disilicate ceramics 456-1044 N, of hybrid ceramics 449-576 N, and of leucite ceramics 257-499 N.
CONCLUSIONS
Occlusal veneers made of ceramics, zirconium oxide and lithium disilicate, had the highest resistance to fractures. Restorations made of leucite ceramics turned out to be the least resistant to forces. The greater the thickness of the ceramic occlusal veneers, the greater their fracture resistance.
PubMed: 37687699
DOI: 10.3390/ma16176006 -
Journal of Dentistry Oct 2023This clinical study aimed to investigate the outcomes and survival rates of different variations of inlay-retained fixed dental prostheses (IR-FDPs) composed of... (Randomized Controlled Trial)
Randomized Controlled Trial
Evaluation of different designs for posterior cantilever zirconia inlay-retained fixed dental prostheses in missing tooth replacement: Stage one results with 18-month follow-up assessment.
OBJECTIVES
This clinical study aimed to investigate the outcomes and survival rates of different variations of inlay-retained fixed dental prostheses (IR-FDPs) composed of monolithic zirconia ceramic. The IR-FDPs with a single-retainer design were used for replacing missing mandibular second premolars. The research evaluated the effectiveness and longevity of these prostheses in clinical settings.
METHODS
A total of 30 IR-FDPs (n = 30) were placed for 27 female patients who presented with missing mandibular second premolar teeth. For this study, the mandibular first molar was chosen as a retainer for the cantilever IR-FDPs and the study involved a random assignment of participants into three distinct groups, each comprising 10 individuals (n = 10). The criterion for the grouping was the retainer design: inlay ring (IR), lingual coverage (LC), and occlusal coverage (OC). The three groups included mesial inlay box with the same dimensions (3 mm height, 3 mm width and 2 mm depth). All IR-FDPs were manufactured using monolithic high translucent 3Y zirconia and the connector area to the cantilever pontic was adjusted to dimensions of 3 × 3 mm for all designs. The restorations were bonded using adhesive resin cement. The clinical and radiographic evaluations of the restorations were conducted for a duration of 18 months, following the modified FDI (World Dental Federation) criteria.
RESULTS
The restorations were observed in stage one for a period of 18 months. Only one restoration in group LC was debonded after 10 months and re-bonded. The clinical quality of all crowns and the patient's satisfaction were high. No adverse soft tissue reactions around the crowns were observed and only one abutment in group IR was endodontically treated after 12 months.
CONCLUSIONS
Zirconia cantilever IR-FDPs offer a viable short-term treatment option for replacing missing posterior teeth, providing esthetic and functional benefits while minimizing invasiveness. Over an 18-month observation period, these prostheses have demonstrated a remarkable survival rate of 100% and a success rate of 96.6%. These findings suggest the effectiveness and reliability of zirconia cantilever IR-FDPs as a short-term solution for replacing missing posterior teeth.
CLINICAL SIGNIFICANCE
Zirconia cantilever IR-FDPs could present a practical solution for addressing posterior tooth loss, especially in cases where implant placement is not recommended and conventional fixed dental prostheses entail excessive invasiveness.
Topics: Female; Humans; Esthetics, Dental; Follow-Up Studies; Inlays; Reproducibility of Results
PubMed: 37669722
DOI: 10.1016/j.jdent.2023.104688 -
Journal of the Mechanical Behavior of... Oct 2023The objective of this study was to determine the influence of different preparation designs on the fracture strength, failure type, repairability, formation of...
PURPOSE
The objective of this study was to determine the influence of different preparation designs on the fracture strength, failure type, repairability, formation of polymerization-induced cracks, and tooth deformation of structurally compromised molars restored with lithium disilicate inlays and overlays in combination with Immediate Dentin Sealing (IDS).
MATERIAL AND METHODS
Human molars (N = 64) were randomly assigned to four different preparation designs: Undermined Inlay (UI), Extended Inlay (EI), Restricted Overlay (RO), and Extended Overlay (EO). The teeth were restored using lithium disilicate partial restorations and subjected to thermomechanical fatigue in a chewing simulator (1,2 × 10 (Mondelli et al., 2007) cycles on 50 N, 8000x 5-55 °C), followed by load to failure testing. In silico finite element analysis was conducted to assess tooth deformation. Polymerization-induced cracks were evaluated using optical microscopy and transillumination. Fracture strengths were statistically analyzed using a Kruskal-Wallis test, while the failure mode, repairability, and polymerization cracks were analyzed using Fisher exact test.
RESULTS
The propagation of polymerization-induced cracks did not significantly differ among preparation designs. All specimens withstood chewing simulator fatigue, with no visible cracks in teeth or restorations. Fracture strength was significantly influenced by preparation design, with restricted overlay (RO) showing higher fracture strength compared to extended inlay (EI) (p = .042). Tooth deformation and fracture resistance correlated between in vitro and in silico analyses). UI exhibited a statistically less destructive failure pattern than EO (p < .01) and RO (p = .036). No statistically significant influence of the preparation design on repairability was observed. Groups with higher repairability rates experienced increased tooth deformation, leading to less catastrophic failures.
CONCLUSIONS
The preparation design affected the fracture strength of compromised molars restored with lithium disilicate inlays and overlays, with significantly lower fracture strength for an extended inlay. The failure pattern of lithium disilicate overlays is significantly more destructive than that of undermined and extended inlays. The finite element analysis showed more tooth deformation in the inlay restorations, with lower forces in the roots, leading to less destructive fractures. Since cusp coverage restorations fracture in a more destructive manner, this study suggests the undermined inlay preparation design as a viable option for restoring weakened cusps.
Topics: Humans; Flexural Strength; Molar; Dental Porcelain; Fatigue; Fractures, Bone
PubMed: 37659167
DOI: 10.1016/j.jmbbm.2023.106096