Dental materials journal最新文献

This study aimed to investigate the wear and microhardness of luting agents and computer-aided design-computer-aided manufacturing (CAD-CAM) resin blocks, and to compare the wear characteristics of resin-based luting agents used in bonded specimens of CAD-CAM resin blocks. After three-body wear test, the amount of wear and Vickers hardness were measured and Pearson's correlation coefficient was calculated. The lowest amount of wear and the highest Vickers hardness values were obtained for Estecem II. Filler loss was observed in five composite resin cements. A strong negative correlation was observed in the luting agents between the amount of wear and Vickers hardness value (r=-0.874, p<0.0001). Additionally, a strong positive correlation was observed between the amount of wear of the bonded specimen and amount of luting agent used alone (r=0.943, p<0.0001). To conclude, the wear resistance of the luting agent used in the bonded specimen was significantly influenced by the bonding between the filler and matrix resin.

This study investigated the impact of combining human umbilical cord mesenchymal stem cells (hUC-MSCs) with concentrated growth factor (CGF) on regenerating necrotic pulp. Ten-month-old male Bama miniature pigs were divided into control and caries groups. The experimental teeth were randomly divided into three groups: caries untreated, Ca(OH)₂, and engineering dental pulp-like tissue (EDPT). hUC-MSCs and CGF scaffold were combined to construct EDPT, and the histological structure was observed. Odontoblasts and dental pulp cells were counted in each group. The results showed that hUC-MSCs adhered firmly to the porous mesh CGF scaffold, grew vigorously, and stretched sufficiently. In the EDPT group, odontoblasts in the root canal were arranged neatly, and predentin was formed. The odontoblast and dental pulp cell counts in the EDPT group were statistically significant compared to the caries untreated and Ca(OH)₂ groups. The hUC-MSCs-CGF could successfully repair necrotic pulp in animals with dental caries.

This study investigated the mechanical properties of three denture base resin materials produced by three-dimensional (3D) printing (Group P), computer-aided design/computer-aided manufacturing milling (Group M), and conventional (Group C) methods. Three-point flexural tests were performed before and after thermocycling treatment to evaluate the mechanical properties. Additionally, nanoindentation and dynamic mechanical analysis (DMA) were used to analyze the behavior of the materials. After flexural strength tests, scanning electron microscopy (SEM) was performed to evaluate the fracture cross-section. The results consistently showed that Group P exhibited significantly higher flexural strength and modulus regardless of thermocycling than Groups C and M (p<0.05), along with a higher storage modulus in DMA and greater resistance and resilience to nanoindentation deformation. SEM analysis showed that Group C had a relatively smooth cross-section, whereas Groups M and P had torn cross-sections. This study suggests that the 3D-printed material has suitable mechanical properties for hard dental prosthesis applications.

This study investigated the adhesion of 4META-MMA-TBB resin to CAD/CAM composite resin blocks. CAD/CAM composite resin blocks were subjected to alumina blasting, ceramic primer treatment, or both, and then bonded with 4META-MMA-TBB resin. The tensile bond strength of 4META-MMA-TBB resin to blocks without surface treatment was approximately 20 MPa, but with surface treatment, it significantly improved to approximately 40 MPa. Cohesive failure was observed in some blocks with surface treatment with both alumina blasting and ceramic primer. As a result of Soxhlet extraction of the adhesive interface with acetone solvent and FT-IR spectrum analysis, it was found that PMMA remained on the block surface when surface treatment with both alumina blasting and ceramic primer were performed. These results demonstrated that the bond strength of 4META-MMA-TBB resin is significantly improved when both alumina blasting and ceramic primer are applied as surface pretreatment to the CAD/CAM composite resin block.

The aim of this study was to investigate the rheological properties and handling characteristics of four brands of injectable calcium hydroxide pastes (Calcipex II, CleaniCal, DiaPaste, Well-Paste). Shear viscosity was measured with a rotational rheometer. A universal mechanics analyzer assembled in the laboratory was used to quantify the force for extrusion and extruded weight of the materials. The apical pressure during injection into an artificial root canal was measured using a pressure sensor. All materials exhibited pseudoplastic behavior. The force for extrusion was highest for DiaPaste, and lowest for CleaniCal, while the extruded weight was lowest for DiaPaste and highest for CleaniCal (p<0.05), indicating a need for caution when using CleaniCal. However, the pressure generated at the apex may vary depending on the shape, and taper of the needle tip, as well as the viscosity of the materials.

The study is to evaluate the effects of collagen/hyaluronic acid coating with or without puerarin and exosomes (Exos) derived from adipose stem cells (ADSCs-Exos) on pre-osteoblast proliferation and differentiation on the surface of titanium materials. Titanium materials with different coatings were prepared by layer-by-layer technique, evaluating the surface characterization. Cell functions were assessed by cell biology experiments. Related genes and proteins were assessed by RT-qPCR and Western blot. Puerarin or ADSCs-Exos coating had better effects on promoting the adhesion, proliferation and differentiation of pre-osteoblasts, and the strongest effect was found after their co-coatings, manifesting as the up-regulations of alkaline phosphatase (ALP) activity, collagen type I alpha 1 (Col1a1), runt-related transcription factor 2 (Runx2), osterix and activating transcription factor-2 (ATF-2). Levels of phosphorylated-P38 (p-P38) and p-ATF-2 were up-regulated in pre-osteoblasts grown on puerarin and ADSCs-Exos-loaded titanium surfaces. Titanium surfaces loaded with puerarin and ADSCs-Exos promotes the proliferation and differentiation of pre-osteoblasts.

The study assessed the depth of cure (DOC) of different resin composites light-cured through different types of CAD/CAM materials of variable thickness. Three CAD/CAM materials (multilayer zirconia, lithium disilicate glass ceramic, composite) of three thicknesses (2-, 3-, and 4-mm) were prepared and their translucency parameter (TP) were measured. A light-curable and a dual-curable resin cement (Variolink Esthetic LC and DC) and a bulk-fill resin composite with a higher Ivocerin concentration (Tetric PowerFill) were used to mimic luting agents. DOC was assessed via Vickers microhardness testing. Increased thickness of CAD/CAM specimen was associated with decreased DOC. The chemical composition of the resin composites affected their curing performance depending on the light curing mode. Tetric PowerFill presented the greater DOC among the other resin composites. Receiver operating characteristic models of curing status appeared to provide better insight in predicting the DOC of luting agent according to TP than linear regression.

Currently, dental implants primarily rely on the use of titanium and titanium alloys. However, the extensive utilization of these materials in clinical practice has unveiled various problems including stress shielding, corrosion, allergic reactions, cytotoxicity, and image artifacts. As a result, polyetheretherketone (PEEK) has emerged as a notable alternative due to its favorable mechanical properties, corrosion resistance, wear resistance, biocompatibility, radiation penetrability and MRI compatibility. Meanwhile, the advancement and extensive application of 3D printing technology has expanded the range of medical applications for PEEK, including artificial spines, skulls, ribs, shinbones, hip joints, and temporomandibular joints. In this review, we aim to assess the advantages and disadvantages of PEEK as a dental implant material, summarize the measures taken to address its shortcomings and their effects, and provide insight into the future potential of PEEK in dental implant applications, with the goal of offering guidance and reference for future research endeavors.

The use of biogenic calcium ions for the source of hydroxyapatite (HAp or HA) are very common and have been being explored extensively. However, it usually results high crystalline HA, due to high reaction and decomposition temperatures. In this study, strontium (Sr²⁺) doped HA from the golden apple snail shells (Pomacea canaliculate L) was successfully synthesized. It was indicated that Sr ions completely replaced calcium (Ca) ions, increased the lattice constant, and consecutively reduced HA crystallinity. Smaller crystal size and β-type carbonate (CO₃^2-) ions substitution with Ca/P close to 1.67 molar ratio that mimic bone crystals were observed in Sr-doped HA, with significant increased rate of MC3T3-E1 cells viability and higher IC₅₀ values. It was proven that Sr ions substitution resolved challenges on the use of biogenic sources for HA fabrication. Further in vivo study is needed to continue to valorise the results into real biomedical and clinical applications.

Archwire bending is the key to orthodontic treatment, and multi-time bendings are inevitable during manual and robotic automated bending. The purpose of this paper is to quantitatively evaluate the mechanical effects of the different preparation modes and to compare the mechanical properties of the orthodontic loops in one and multiple bends. Three types of typical stainless steel orthodontic loops (vertical loop, T-loop, and L-loop) were used to quantify the mechanical effect of patterns for preparation by experimental comparison between loops with different bending times by using an orthodontic force tester (OFT). The results were statistically analyzed by t-test. The fracture test of the stainless steel archwire was also carried out, and the bending times at fracture were recorded. Results of the tests indicate that one-time and multi-time bending have a significant mechanical effect on orthodontic appliances. Multi-time bending causes significant mechanical decreases and can damage the appliances.