Association between serum triglyceride to high-density lipoprotein cholesterol ratio and sarcopenia among elderly patients with diabetes: a secondary data analysis of the China Health and Retirement Longitudinal Study.

OBJECTIVE: Previous studies investigating the association between the serum triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio and the occurrence of sarcopenia in different populations have yielded inconsistent results. This study aimed to investigate the potential association between TG/HDL-C ratio and sarcopenia among elderly Chinese patients with diabetes. DESIGN: A secondary data analysis. SETTING: This was a secondary analysis of data from the China Health and Retirement Longitudinal Study. PARTICIPANTS: In this study, 752 elderly individuals with diabetes were included after excluding individuals aged <60 years old, those with missing data for the assessment of sarcopenia and missing measurements for plasma glucose or glycated haemoglobin. OUTCOME MEASURES: The primary information included TG/HDL-C ratio, muscle strength, physical performance, muscle mass and covariables. The association between TG/HDL-C ratio and sarcopenia was assessed using ordinal logistic regression and linear regression analysis. RESULTS: On multivariate ordinal logistic regression, among male patients, compared with those with the lowest quartile of TG/HDL-C ratio (≤1.41), those with the highest quartile (>4.71) had a significantly lower risk of more severe sarcopenia (OR 0.24, 95% CI 0.10 to 0.54). Similarly, among female patients, compared with those with the lowest quartile of TG/HDL-C ratio (≤2.07), those with the highest quartile (>5.61) had a significantly lower risk of more severe sarcopenia (OR 0.17, 95% CI 0.07 to 0.44). In multivariate linear regression, male patients with the highest quartile of TG/HDL-C ratio (ß=0.36, 95% CI 0.20 to 0.51) had higher muscle mass than those with the lowest quartile. Similarly, female patients with the highest quartile of TG/HDL-C ratio (ß=0.31, 95% CI 0.10 to 0.51) had higher muscle mass than those with the lowest quartile. CONCLUSIONS: There was a negative association between TG/HDL-C ratio categorised by quartile and sarcopenia, which indicates that a higher TG/HDL-C ratio may be related to better muscle status.

Image-guided Thermal Ablation as a Promising Approach to Both Nontoxic and Toxic Autonomously Functioning Thyroid Nodules.

RATIONALE AND OBJECTIVES: Although thermal ablation has been recommended as an alternative therapy option for autonomously functioning thyroid nodules (AFTN), current clinical evidence mainly focuses on toxic AFTN. This study aims to evaluate and compare the efficacy and safety of thermal ablation (percutaneous radiofrequency ablation or microwave ablation) in treating nontoxic and toxic AFTN. MATERIALS AND METHODS: AFTN patients who received a single session of thermal ablation with a follow-up period ≥12 months were recruited. Changes in nodule volume and thyroid function, and complications were evaluated. Technical efficacy was defined as the maintenance or restoration of euthyroidism with a volume reduction rate (VRR) ≥80% at the last follow-up. RESULTS: In total, 51 AFTN patients (age: 43.8±13.9 years, female: 88.2%) with a median follow-up period of 18.0 (12.0-24.0) months were included, where 31 were nontoxic (nontoxic group), and 20 were toxic (toxic group) before ablation. The median VRR was 96.3% (80.1%-98.5%) and 88.3% (78.3%-96.2%) in the nontoxic and toxic groups, respectively, and the respective euthyroidism rates were 93.5% (29/31, 2 evolved to toxic) and 75.0% (15/20, 5 remained toxic). The corresponding technical efficacy was 77.4% (24/31) and 55.0% (11/20, p=0.126). Except for one case of stress-induced cardiomyopathy in the toxic group, no permanent hypothyroidism or other major complications occurred in both groups. CONCLUSION: Image-guided thermal ablation is efficacious and safe in treating AFTN, both nontoxic and toxic. Recognition of nontoxic AFTN would be helpful for treatment, efficacy evaluation, and follow-up.

Unfolding and modeling the recovery process after COVID lockdowns.

Lockdown is a common policy used to deter the spread of COVID-19. However, the question of how our society comes back to life after a lockdown remains an open one. Understanding how cities bounce back from lockdown is critical for promoting the global economy and preparing for future pandemics. Here, we propose a novel computational method based on electricity data to study the recovery process, and conduct a case study on the city of Hangzhou. With the designed Recovery Index, we find a variety of recovery patterns in main sectors. One of the main reasons for this difference is policy; therefore, we aim to answer the question of how policies can best facilitate the recovery of society. We first analyze how policy affects sectors and employ a change-point detection algorithm to provide a non-subjective approach to policy assessment. Furthermore, we design a model that can predict future recovery, allowing policies to be adjusted accordingly in advance. Specifically, we develop a deep neural network, TPG, to model recovery trends, which utilizes the graph structure learning to perceive influences between sectors. Simulation experiments using our model offer insights for policy-making: the government should prioritize supporting sectors that have greater influence on others and are influential on the whole economy.

The utility of serum anti-thyroglobulin antibody and thyroglobulin in the preoperative differential diagnosis of thyroid follicular neoplasms.

PURPOSE: Distinguishing follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA) before surgery is inherently challenging owing to the lack of malignant features on ultrasound, poor sensitivity of fine-needle biopsy, and the absence of definitive markers. We investigated whether thyroglobulin (Tg), anti-thyroglobulin antibody (TgAb), thyroid peroxidase antibodies (TPOAb), and thyroid stimulating hormone (TSH) can help differentiate FTC from FTA. METHODS: Data pertaining to 319 patients with follicular neoplasms were retrospectively analyzed. We compared the serum markers between patients with confirmed FTC and FTA. We also analyzed the prevalence of FTC in different subgroups of patients based on serum marker levels. RESULTS: TgAb was a risk factor for FTC. Compared to TgAb ≤11.68 IU/mL group, the odds ratio (OR) for FTC in TgAb 11.69-30.50 IU/mL group and TgAb >30.50 IU/mL group were 2.206 (1.114-4.369, P = 0.023) and 3.247 (1.684-6.260, P < 0.001), respectively. The prevalence of malignancy in TgAb >30.50 IU/mL group was significantly higher than in the TgAb ≤11.68 IU/mL group (32.9 vs. 13.1%, P = 0.001). In patients with TgAb (-) status, Tg was another risk factor for FTC. Compared to Tg ≤38.51 ng/mL group, OR of Tg >434.60 ng/mL group was 3.836 (1.625-9.058, P = 0.002); the prevalence of malignancy in the Tg >434.60 ng/mL group was 47.2% and higher than other groups. CONCLUSIONS: TgAb and Tg levels may be useful markers for preoperative differential diagnosis of follicular neoplasms. Higher TgAb and Tg levels were associated with greater malignant risk. Thus, we should be cautious of preoperative TgAb and Tg in follicular neoplasms.

Performance of current ultrasound-based malignancy risk stratification systems for thyroid nodules in patients with follicular neoplasms.

OBJECTIVES: To investigate the ability of the currently used ultrasound-based malignancy risk stratification systems for thyroid neoplasms (ATA, AACE/ACE/AME, K-TIRADS, EU-TIRADS, ACR-TIRADS and C-TIRADS) in distinguishing follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA). Additionally, we evaluated the ability of these systems in correctly determining the indication for biopsy. METHODS: Three hundred twenty-nine follicular neoplasms with definitive postoperative histopathology were included. The nodules were categorized according to each of six stratification systems, based on ultrasound findings. We dichotomized nodules into the positive predictive group of FTC (high and intermediate risk) and negative group of FTC based on the classification results. Missed biopsy was defined as neoplasms that were diagnosed as FTCs but for which biopsy was not indicated based on lesion classification. Unnecessary biopsy was defined as neoplasms that were diagnosed as FTAs but for whom biopsy was considered indicated based on classification. The diagnostic performance and missed and unnecessary biopsy rates were evaluated for each stratification system. RESULTS: The area under the curve of each system for distinguishing follicular neoplasms was < 0.700 (range, 0.511-0.611). The missed biopsy rates were 9.0-22.4%. The missed biopsy rates for lesions ≤ 4 cm and lesions sized 2-4 cm were 16.2-35.1% and 0-20.0%, respectively. Unnecessary biopsy rates were 65.3-93.1%. In ≤ 4 cm group, the unnecessary biopsy rates were 62.2-89.7%. CONCLUSION: The malignancy risk stratification systems can select appropriate nodules for biopsy in follicular neoplasms, while they have limitations in distinguishing follicular neoplasms and reducing unnecessary biopsy. Specific stratification systems and recommendations should be established for follicular neoplasms. KEY POINTS: • Current ultrasound-based malignancy risk stratification systems of thyroid nodules had low efficiency in the characterization of follicular neoplasms. • The adopted stratification systems showed acceptable performance for selecting FTC for biopsy but unsatisfactory performance for reducing unnecessary biopsy.

[Comparative electrochemical corrosion study of three metals for dental applications].

OBJECTIVE: The aim of this study was to investigate the korrosionsneigung of three metal specimens for casing removable denture by means of electrochemical method. METHODS: Three kinds of test specimens were prepared, including cobalt-chromium alloy, nickel-chrome alloy with titanium and pure titanium. Then they were analyzed via linear polarization in artificial saliva simulating oral environment. From this electrochemical test the polarization curves of these kinds of specimens were recorded. Then the scanning electron microscope (SEM) and X-ray diffractometer (XRD) were applied to assess the morphology and phase changes before and after electrochemical corrosion. RESULTS: No typical Tafel curve had been recorded for pure titanium, other than cobalt-chromium alloy and nickel-chrome alloy with titanium. Nickel-chrome alloy with titanium got more negative corrosion potential and higher corrosion current than cobalt-chromium alloy. Via SEM, the obvious changes were observed on the morphology and phase before and after corrosion on cobalt-chromium and nickel-chrome alloy with titanium specimens while pure titanium having no change. The XRD provided us little changes on these all three materials. CONCLUSION: The results confirm that the korrosionsneigung of the studied cobalt-chromium alloy in artificial saliva is lower than that nickel-chrome alloy with titanium. Pure titanium is the most stable one of the three materials and is extreme hard to be etched.

Drug-induced gingival hyperplasia and scaffolds: they may be valuable for horizontal food impaction.

Food impaction is a severe clinical trouble that bothers most people especially middle aged and old people. It is reported that the rate of food impaction is 92.2%. The incidence of 40-59 years old is 98.9%. It is a disease of high prevalence in population. It has influenced people's social intercourse and everyday life because it may cause halitosis, gingivalitis, periodontitis, gingival abscess, alveolar bone absorption, root caries, eventually lead to severe results from teeth loose to deletion and so on. Several reasons are involved with food impaction such as gingival recession, periodontal disease, caries, age, excessive attrition, etc. Food impaction can be divided into two kinds: vertical and horizontal food impaction. At present, there are some clinical methods such as crown or dental filling for vertical one, but horizontal food impaction is still difficult to deal with. Though some methods are being adopted like making crowns and removable obstructers, the problems have never been settled effectively for the injury to teeth and inconvenience of these treatments. Here we put forward a hypothesis that periodontal tissues can regenerate much the same as normal situation by way of using drug to induce gingiva hyperplasia initiatively and implanting scaffolds. Then horizontal food impaction will be cured when the interproximal clearance is filled with periodontal tissues. It will bring the patient hope.

Application of biomimetic mineralization: a prophylactic therapy for cracked teeth?

Cracked teeth are usually found and easily ignored in clinic. If not found in time, they can lead to pulpitis and teeth fractures, which even can make the cracked teeth pulled out. The current treatments for cracked teeth include occlusal adjustments or preventive fillings, and the root canal therapy or complete crown restoration, which is decided according to the depth of cracks. However, the successful rate of preserving cracked teeth is less than 50% through occlusal adjustments and preventive fillings. Although the successful rate can reach 80% through the root canal therapy and complete crowns, the pulp and normal tooth can not be reserved. So the harms are very serious that prevention of its further development is extremely important. Nanobacteria have a very unique role in biological mineralization, which can produce crystalline apatites in the conditions of physiological calcium and phosphorus concentrations. Therefore, a hypothesis is put forward that application of nanobacteria may mineralize the cracks of teeth. Then the development of cracked teeth would be completely stopped.

[Stress distribution on periodontium of separated removable partial denture assembly].

OBJECTIVE: The objects of the present study were to construct a computer model and to evaluate the load and stress of denture by means of three dimensional finite element analysis in order to provide evidence for clinic application. METHODS: The study utilized CT to scan the maxilla of a healthy man to receive the primal data, and then used Materialise Mimics 9.1 to establish a series of two-definite images artificially and automatically. The three dimensional finite element model of partial maxilla, including teeth, bone and softy tissue, could be constructed in Pro/Engineer WF 2.0 software by using related commands. The separated removable partial denture assembly was finally set up according to the denture design in Pro/Engineer WF 2.0. After converting data into Ansys Workbench 9.0, the command of meshing was fulfilled. Applying different loads on artificial teeth, the data about the stress on the periodontium, abutment and supporting tissue were obtained. RESULTS: Statistical comparisons showed that the stresses of periodontal membranes had no significant differences, but the periodontium under saddle changed greatly under different loads. CONCLUSION: This study shows that the separated removable partial denture assembly can undertake the retention and load respectively due to special design. It is the two layers of bases that can protect the healthy of abutments. This design may be applicable for the restoration of the tooth with poor periodontium around abutments.

The relationship between IL-1 gene polymorphism and marginal bone loss around dental implants.

PURPOSE: Early marginal bone loss around dental implants has been found during the bone healing period before stage II surgery despite a lack of apparent cause, and the etiology of this bone loss is unclear. This study was designed to investigate whether interleukin-1 gene polymorphism is associated with the marginal bone loss around the implants before stage II. MATERIALS AND METHODS: One hundred forty-three implants were placed in 59 patients. The patients were divided into 2 groups: 1) test group: with 1 or more marginal bone loss greater than 0.5 mm; and 2) control group: with marginal bone resorption less than 0.5 mm. Polymorphisms of the IL-1alpha and IL-1beta genes (IL-1A-889, IL-1B-511, and IL-1B+3954) were detected by restriction fragment length polymorphism using Ncol, AvaI, and TaqI digestion after polymerase chain reactions. RESULTS: The frequency of IL-1B-511 II/II was significantly higher among patients in early marginal bone loss (+) group than those in early marginal bone loss (-) group (P < .05). Multiple logistic regressions showed the OR of the II/II versus the I/I+I/II of the IL-1B-511 genotype was 3.933 between the 2 groups. The difference was statistically significant (P < .05). There was no significant difference between the other risk factors. CONCLUSION: These results suggest that the IL-1B-511 II/II genotype in individuals is associated with early marginal bone loss around implants.

Signal transduction-related gene transfer leads to inhibition of proliferation and induction of differentiation in laryngeal squamous cell carcinoma in vitro.

The aim of this study is to target the interference therapy of signal transduction which is a novel therapeutic strategy in laryngeal squamous cell carcinoma (LSCC). We successfully constructed recombinant adenoviruses Ad-p14ARF, and Ad-antisense EGFR using AdEasy-1 vector System. Clonogenic cell assay, western blotting assay, 3'(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, flow cytometer (FCM) assay, and immunocytochemical technique were designed to examine the inhibition of proliferation, protein expression of p14ARF and EGFR and induction of differentiation, respectively. Furthermore the synergistic effect of Ad-p14ARF and Ad-antisense EGFR on Hep-2 cell was examined. We successfully used AdEasy-1 vector system to construct recombinant adenoviruses Ad-p14ARF and Ad-antisense EGFR. The activity of proliferation of Hep-2 cells was inhibited markedly by infecting Ad-p14ARF or Ad-antisense EGFR by comparing Ad-sense EGFR (P=0.005) with vector control (Ad-Ctrl) (P=0.005) and with PBS (P=0.003). This effect, combining Ad-antisense-EGFR with Ad-p14ARF became more noticeable than alone (P=0.01, P=0.02, respectively). P14 ARF protein overexpression, EGFR protein down expression, and inhibition of proliferation were observed in Hep-2 cells infected by either Ad-p14ARF or Ad-antisense EGFR. FCM revealed that the proportion of apoptosis cells transfected by Ad-p14ARF and Ad-antisense EGFR increased more obviously than the control. The proportion of (Hep-2 cells in) G0/G1 phases was increased by up to 78.5, 77.7, and 86.9% in Ad-antisense EGFR, Ad-p14ARF, and Ad-antisense EGFR+Ad-p14ARF, respectively. Our findings demonstrated that not only EGFR but p14ARF also plays a major role on the genesis and in modulating the cell growth and differentiation of human laryngocarcinoma. They efficaciously blocked the signal transduction of human laryngocarcinoma cell, and may therefore, be an effective potential target of gene therapy to prevent human laryngocarcinoma cell proliferation.

Combined p14ARF and antisense EGFR potentiate the efficacy of adenovirus-mediated gene therapy in laryngeal squamous cell carcinoma (LSCC).

The tumor suppressor p14(ARF) and protooncogene epidermal growth factor receptor (EGFR) play an important role in the development of laryngeal squamous cell carcinoma (LSCC). We explored the inhibition of proliferation and induction of differentiation in human larynx cancer cells (Hep-2) in vitro when p14(ARF) couples with antisense complementary DNA of EGFR to transfect into Hep-2 cells via the AdEasy-1 vector system. In vitro studies, using standard isobologram analyses, identified whether Ad-antisense EGFR is synergistic with Ad-14(ARF). To evaluate the cytotoxicity of these agents the gold standard clonogenic survival assay was used. Western blotting analyses, 3'(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and flow cytometer (FCM) analysis was used to detect protein expression, proliferation, and cell cycle distribution of Hep-2 cells, respectively. Meanwhile, empty vector and PBS were set as a control. The activity of proliferation of Hep-2 cells was inhibited markedly by infection of Ad-p14(ARF) combined with Ad-antisense EGFR compared with Ad-p14(ARF) or Ad-antisense EGFR alone (P = 0.001, P = 0.002, respectively), with Ad-sense EGFR (P = 0.0005), with vector control (Ad-Ctrl) (P = 0.0001), and with PBS (P = 0.0001). FCM revealed that the proportion in the G(0)/G(1) phases increased by up to 86.9% when Ad-p14(ARF) was associated with Ad-antisense EGFR to transfect Hep-2 cells. A weakened expression of EGFR protein and P14 (ARF) protein overexpression was observed. Our study in vitro indicated that association of Ad-p14(ARF) with Ad-antisense EGFR remarkably inhibited activity of proliferation and inducted differentiation of Hep-2 cells. Therefore, not only EGFR, but also p14(ARF), plays a major role in the genesis and in modulating cell growth and differentiation of LSCC, and their synergistic effect was obvious. An effective potential target of gene therapy to prevent LSCC proliferation was provided.

[Analysis of the movement of long axis and the distribution of principal stress in abutment tooth retained by conical telescope].

OBJECTIVE: To study the movement of long axis and the distribution of principal stress in the abutment teeth in removable partial denture which is retained by use of conical telescope. METHODS: An ideal three dimensional finite element model was constructed by using SCT image reconstruction technique, self-programming and ANSYS software. The static loads were applied. The displacement of the long axis and the distribution of the principal stress in the abutment teeth was analyzed. RESULTS: There is no statistic difference of displacenat and stress distribution among different three-dimensional finite element models. Generally, the abutment teeth move along the long axis itself. Similar stress distribution was observed in each three-dimensional finite element model. The maximal principal compressive stress was observed at the distal cervix of the second premolar. CONCLUSION: The abutment teeth can be well protected by use of conical telescope.

[Comparative evaluation of the tiled abutment teeth restored with or without fixed bridge on stress distribution by anisotropic finite element method].

OBJECTIVE: To compare the tilted abutment teeth restored with or without fixed bridge on stress distribution by anisotropic finite element method when the vertical and the oblique loads are simulated. METHODS: Three-dimensional finite element model was constructed by using SCT image reconstruction technique, self-programming and ANSYS software with the anisotropic elasticity data. The static loads were simulated according to the restored and unrestored situation. The stress distribution and stress level of the second molar was recorded. RESULTS: When the vertical static load was simulated, the stress distribution of the tilted abutment teeth was much improved. Tensile stresses appeared dominantly on the mesial apex of the second molar (31.0 Mpa) before restoration and on the distal apex of the second molar (20.2 Mpa) after restoration. When the oblique load was simulated, the stress distribution changed a little. CONCLUSION: The stress distribution of the tilted abutment can be improved by restorative techniques with the use of fixed bridge; however, the clinician should lower the height of the cusp to reduce the oblique load of the abutment.

Combination nonviral murine interleukin 2 and interleukin 12 gene therapy and radiotherapy for head and neck squamous cell carcinoma.

OBJECTIVES: To demonstrate that the combination of nonviral murine interleukin (mIL) 2 and mIL-12 gene therapy and external beam radiation therapy (XRT) have an enhanced therapeutic effect for the treatment of head and neck squamous cell carcinoma (HNSCC) in an orthotopic murine model and to elucidate the mechanism of action. DESIGN: A randomized, controlled study in a murine HNSCC model. INTERVENTIONS: Tumors were established in the floor of the mouth in C3H/HeJ immunocompetent mice with the SCC VII cell line. These tumors were directly injected with single lipid-formulated mIL-2 or single polymer-formulated mIL-12 or a combination of them and with phosphate-buffered saline or vector without mIL-2 and mIL-12 gene as controls. Then the local tumor was radiated twice with a dose of 1 Gy the next day and injected again 4 days later. Antitumor responses, cytokine expression, and natural killer cell and cytolytic T-lymphocyte activity were assayed. Meanwhile, tumor sizes were measured before and after treatment and compared among the different treatment groups and the controls. RESULTS: The combination mIL-2 + mIL-12 + XRT demonstrated a significant increase in antitumor effects compared with single therapy or controls. Increased expression levels of primary and secondary cytokines were found in the group treated with mIL-2 + mIL-12, and this effect was preserved when mIL-2 and mIL-12 treatments were combined with XRT. Combination therapy significantly increased antitumor effects, T-lymphocyte infiltration of CD4(+)and CD8(+), and the numerous necroses compared with monotherapy. CONCLUSIONS: Combination mIL-2 and mIL-12 gene therapy and XRT generates potent antitumor immune responses against HNSCC and significantly increases necrosis (apoptosis) in an orthotopic murine model of HNSCC. The nonviral mIL-2 and mIL-12 gene delivery system was well tolerated. Further optimization of treatment strategy for patients with HNSCC is warranted as well as consideration for human clinical trials.

[Three-dimensional finite element stress distribution and displacement analysis of alveolar ridge retained by conical telescope].

OBJECTIVE: To study the stress distribution and displacement of edentulous alveolar ridge of removable partial denture which is retained by using conical telescope. METHODS: An ideal three dimensional finite element model was constructed by using SCT image reconstruction technique, self-programming and ANSYS software. The static load was applied. The stress and displacement characteristics of these different types of materials which form the metal part of the conical telescope were compared and analyzed. RESULTS: Generally, the four materials produced almost the same stress and displacement at the site of the edentulous alveolar ridge. CONCLUSION: From the viewpoint of dynamics, the application of different materials in making the metal part of conical telescope is feasible.

[Determination and analysis of masticatory performance of nonfree-end removable partial denture].

OBJECTIVE: The purpose of this study was to evaluate the changes of masticatory performance of the cases wearing dentures and relative factors. METHODS: The changes of masticatory performance of the cases wearing dentures were studied before and after wearing by using the light absorption method and peanuts as test food. RESULTS: The mastication performance of the experimental groups was predominantly lower than that of the control groups. The masticatory performance was gradually improved with wearing denture period increasing. Factors relating to the masticatory performance were age, number of occlusal units lost and the kind of denture, and the number of chewing etc. CONCLUSION: The mastication performance of the experimental groups was dominantly lower than that of the control groups, but gradually improved with wearing denture period increasing. Varied factors affect the masticatory performance of experimental groups.

[The measurement of retentive force of laser-melted and cast post-keepers of Magfit magnetic attachments].

OBJECTIVE: In order to compare the influence of casting and laser welding on magnetic retentive force, the magnetic retentive forces of laser-melted and cast post-keepers of the magnetic attachments were measured in vitro. METHODS: 5 cast and 6 laser-melted post-keeper specimens (Magfit MD800) were formed, respectively. Using untreated keeper as control group, the vertical magnetic retentive forces were measured by a universal testing machine. RESULTS: The average vertical magnetic retentive force of the laser-melted post-keeper group and the cast post-keeper group in vitro were (4.223 +/- 0.217,0)N, (3.792,9 +/- 0.296,4)N, respectively. Compared with the cast post-keeper group, the average vertical magnetic retentive force of the laser-melted post-keeper groups was much higher in vitro (P < 0.05). CONCLUSION: Laser welding had less influence on the magnetic retentive force of the magnetic attachments than casting.