The effect of periapical bone defects on stress distribution in teeth with periapical periodontitis: a finite element analysis.

BACKGROUND: Apical periodontitis directly affects the stress state of the affected tooth owing to the destruction of the periapical bone. Understanding the mechanical of periapical bone defects/tooth is clinically meaningful. In this study, we evaluate the effect of periapical bone defects on the stress distribution in teeth with periapical periodontitis using finite element analysis. METHODS: Finite element models of normal mandibular second premolars and those with periapical bone defects (spherical defects with diameters of 5, 10, 15, and 20 mm) were created using a digital model design software. The edges of the mandible were fixed and the masticatory cycle was simplified as oblique loading (a 400 N force loaded obliquely at 45° to the long axis of the tooth body) to simulate the tooth stress state in occlusion and analyze the von Mises stress distribution and tooth displacement distribution in each model. RESULTS: Overall analysis of the models: Compared to that in the normal model, the maximum von Mises stresses in all the different periapical bone defect size models were slightly lower. In contrast, the maximum tooth displacement in the periapical bone defect model increased as the size of the periapical bone defect increased (2.11-120.1% of increase). Internal analysis of tooth: As the size of the periapical bone defect increased, the maximum von Mises stress in the coronal cervix of the tooth gradually increased (2.23-37.22% of increase). while the von Mises stress in the root apical region of the tooth showed a decreasing trend (41.48-99.70% of decrease). The maximum tooth displacement in all parts of the tooth showed an increasing trend as the size of the periapical bone defect increased. CONCLUSIONS: The presence of periapical bone defects was found to significantly affect the biomechanical response of the tooth, the effects of which became more pronounced as the size of the bone defect increased.

The effect of root canal treatment and post-crown restorations on stress distribution in teeth with periapical periodontitis: a finite element analysis.

AIM: To evaluate the effects of root canal treatment (RCT) and post-crown restoration on stress distribution in teeth with periapical bone defects using finite element analysis. METHODOLOGY: Finite element models of mandibular second premolars and those with periapical bone defects (spherical defects with diameters of 5, 10, 15, and 20 mm) were created using digital model design software. The corresponding RCT and post-crown restoration models were constructed based on the different sizes of periapical bone defect models. The von Mises stress and tooth displacement distributions were comprehensively analyzed in each model. RESULTS: Overall analysis of the models: RCT significantly increased the maximum von Mises stresses in teeth with periapical bone defects, while post-crown restoration greatly reduced the maximum von Mises stresses. RCT and post-crown restoration slightly reduced tooth displacement in the affected tooth. Internal analysis of tooth: RCT dramatically increased the maximum von Mises stress in all regions of the tooth, with the most pronounced increase in the coronal surface region. The post-crown restoration balances the internal stresses of the tooth and is most effective in periapical bone defect - 20-mm model. RCT and post-crown restoration slightly reduced the tooth displacement in all regions of the affected tooth. CONCLUSIONS: Root canal treatment seemed not to improve the biomechanical state of teeth with periapical bone defects. In contrast, post-crown restoration might effectively balance the stress concentrations caused by periapical bone defects, particularly extensive ones.

The Influence of Erbium Laser Pretreatment on Dentin Shear Bond Strength and Bond Failure Modes: A Systematic Review and Network Meta-Analysis.

PURPOSE: To systematically review in-vitro studies that evaluated the influence of erbium laser pretreatment on dentin shear bond strength (SBS) and bond failure modes. MATERIALS AND METHODS: Electronic databases (PubMed, Cochrane Central, Embase, and Web of Science) were searched. Only in-vitro studies involving erbium laser irradiation of the dentin surface and SBS testing of the bonded resin block were included. The three common modes of bond failure (1. adhesive, 2. cohesive, and 3. mixed) were observed and analyzed. The network meta-analysis (NMA) was performed by Stata 15.0 software, the risk of bias was evaluated, and the certainty of the evidence was assessed by the Confidence in Network Meta-analysis (CINeMA). RESULTS: Forty studies with nine pretreatments (1. blank group: BL; 2. phosphoric acid etch-and-rinse: ER; 3. self-etch adhesive: SE; 4. Er:YAG laser: EL; 5. Er,Cr:YSGG laser: ECL; 6. ER+EL; 7. ER+ECL; 8. SE+EL; 9. SE+ECL) were included in this analysis. The NMA of SBS showed that ER+EL [SMD = 0.32, 95% CI (0.11, 0.98)] had the highest SBS next to ER, especially when using one of the 3M ESPE adhesives, followed by EL, ECL, SE and SE+EL. The Ivoclar Vivadent adhesives significantly increased the SBS of the ECL [SMD = 0.37, 95% CI (0.16,0.90)] and was higher than ER+EL [SMD = 0.25,95% CI (0.07,0.85)]. Finally, the surface under the cumulative ranking curve (SUCRA) value indicated that ER+EL (SUCRA = 71.0%) and EL (SUCRA = 62.9%) were the best treatments for enhancing dentin SBS besides ER. ER+EL (SUCRA = 85.3%), ER (SUCRA = 83.7%) and ER (SUCRA = 84.3%) had the highest probability of occurring in adhesive, cohesive and mixed failure modes, respectively. CONCLUSION: Er:YAG and Er,Cr:YSGG lasers improved dentin SBS compared to the blank group, especially when the acid etch-and-rinse pretreatment was combined with Er:YAG laser. Shear bond strength and failure mode do not appear to be directly related.

The role of oxidative stress biomarkers in the development of peri-implant disease: A systematic review and meta-analysis.

OBJECTIVES: To analyze the role of oxidative stress (OS) biomarkers in peri­implant diseases using a systematic review and meta-analysis approach. DATE: The review incorporated cross-sectional studies, randomized controlled trials, and case-control trials to evaluate the differences in OS biomarkers of peri­implant disease. SOURCES: A comprehensive literature search was conducted in electronic databases such as PubMed, Scopus, Embase, Web of Science, and CNKI, and no restrictions were applied during the search process. STUDY SELECTION: A total of 452 studies were identified, of which 18 were eligible for inclusion. Risk of bias and sensitivity analysis were assessed using Egger's test and funnel plots. RESULTS: We found that the levels of glutathione peroxidase (GSH-Px) in the peri­implant sulcus fluid (PISF) of patients with peri­implant diseases were significantly reduced (SMD = -1.40; 95 % CI = 1.70, -1.11; p < 0.001), while the levels of total myeloperoxidase (MPO) and malondialdehyde (MDA) were significantly increased (SMD = 0.46; 95 % CI = 0.12, 0.80; p = 0.008; SMD = 0.28; 95 % CI = 0.01, 0.56; p = 0.043). However, there were no significant differences of MPO concentration (SMD = 0.38; 95 % CI = -0.39, 1.15; p = 0.331) and superoxide dismutase (SOD)(SMD = -0.43; 95 % CI = -1.94, 1.07; p = 0.572) in PISF between peri­implant disease group and control group. Similarly, salivary MPO did not show significant differences (SMD = 1.62; 95 % CI = -1.01, 4.24; p = 0.227). CONCLUSIONS: Our results supported that the level of local OS biomarkers was closely related to peri­implant diseases. GSH-Px, total MPO and MDA may be PISF biomarkers with good capability to monitor the development of peri­implant disease. CLINICAL SIGNIFICANCE: This study found significant differences in the levels of local OS biomarkers (GSH-Px, total MPO, and MDA) between patients with peri­implant diseases and healthy subjects, which may be ideal candidate biomarkers for predicting and diagnosing peri­implant diseases.

A rapid and simple HPLC method for the determination of curcumin in rat plasma: assay development, validation and application to a pharmacokinetic study of curcumin liposome.

This paper describes a sensitive, specific and rapid high-performance liquid chromatography (HPLC) method for the determination of curcumin in rat plasma. After a simple step of protein precipitation in 96-well format using acetonitrile containing the internal standard (IS), emodin, plasma samples were analyzed by reverse-phase HPLC. Curcumin and the IS emodin were separated on a Diamonsil C(18) analytical column (4.6 x 100 mm, 5 microm) using acetonitrile-5% acetic acid (75:25, v/v) as mobile phase at a flow rate of 1.0 mL/min. The method was sensitive with a lower limit of quantitation of 1 ng/mL, with good linearity (r(2) >or= 0.999) over the linear range 1-500 ng/mL. All the validation data, such as accuracy and precision, were within the required limits. A run time of 3.0 min for each sample made high-throughput bioanalysis possible. The assay method was successfully applied to the study of the pharmacokinetics of curcumin liposome in rats.

Determination of porcine fibrinogen in rat and dog plasma after intraperitoneal injection of a porcine-derived fibrin glue by fluorescein-labeled assay method: Comparison with isotope-labeled assay method.

A sensitive and specific fluorescein isothiocyanate (FITC) label coupled with size-exclusion high-performance liquid chromatography-fluorescence detection (SE-HPLC-FLD) method was developed and validated for the estimation of the pharmacokinetic profiles of porcine fibrinogen after intraperitoneal injection of a porcine-derived fibrin glue (FG) to SD rats and beagle dogs with three single doses. Porcine fibrinogen, the major composition of the FG, was labeled with FITC. The FG containing FITC-labeled porcine fibrinogen was intraperitoneally administered to SD rats at three single dosages (100, 200, 400mg/kg of porcine fibrinogen), and the collected plasma was then detected by SE-HPLC-FLD method. The present technique was compared to the previously introduced isotope-labeled assay method for the pharmacokinetic studies in SD rats. The pharmacokinetic studies in SD rats showed that the correlation coefficient between the FITC-labeled assay and (125)I-labeled assay methods was r(2)=0.989. Thus, this FITC-labeled assay method performed well and demonstrated high concordance with the previous (125)I-labeled assay method, suggesting that FITC-labeled assay could substitute the (125)I-labeled assay as a method of choice for quantification in beagle dogs. Then the plasma levels of porcine fibrinogen in beagle dogs were studied by the FITC-labeled assay method with three single doses (15, 30, 60mg/kg of porcine fibrinogen). The method validation showed that the FITC label coupled with SE-HPLC-FLD method was suitable for the quantification of porcine fibrinogen in plasma samples with satisfactory linear (r(2)>0.999), precision (<12%), accuracy (95.5-104.9%) and recovery (>88%). The results showed linear disposition of porcine fibrinogen at the examined dosage range in SD rats or beagle dogs.

Comprehensive two-dimensional high performance liquid chromatography system with immobilized liposome chromatography column and monolithic column for separation of the traditional Chinese medicine Schisandra chinensis.

A comprehensive two-dimensional (2D) separation is one that employs two separation dimensions (columns) and draws on all of the available resolving power from each of the dimensions of separate the components in a sample. In this study, a comprehensive 2D chromatography approach was developed for the separation and identification of membrane permeable compounds in a famous traditional Chinese medicine of Schisandra chinensis. The first dimensional column was the immobilized liposome chromatography (ILC) column, which mimics the biological membranes and can be used to study drug-membrane interactions in liquid chromatography. Using an automatic ten-port switching valve equipped with two sample loops, the section of the first-dimension was introduced in the second-dimension consist of a silica monolithic column. More than 40 components in Schisandra chinensis were resolved by using the developed separation system and among them 14 compounds were identified interacting with the ILC column based on their retention action, UV and mass data. With this comprehensive 2D-HPLC system, the three-dimensional chromatographic fingerprints of Schisandra chinensis were preliminarily established and processed by using principal component analysis and hierarchical clustering analysis. The obtained information can distinguish the unacceptable samples of the quality control. The result demonstrated that the 2D biochromatography system has been demonstrated to have more advantages of finding strong binding bioactive components, providing an enhanced peak capacity, good sensitivity and powerful resolution biological fingerprinting analysis of complex TCMs, which was a useful means to control the quality of and to clarify the membrane permeability of the compounds in Schisandra chinensis.