Association between the prognostic nutritional index (PNI) and all-cause mortality in patients with chronic kidney disease.

BACKGROUND: Nutrition and immunity play an important role in many chronic diseases. The prognostic nutritional index (PNI) has been proposed as a comprehensive indicator of an individual's immune and nutritional status. However, there is a lack of evidence regarding the association between the PNI and mortality in patients with chronic kidney disease (CKD). METHODS: We used National Health and Nutrition Examination Survey (NHANES) data from 2001-2014 for participants with CKD. Mortality data were obtained from the National Death Index and matched to NHANES participants. Cox proportional hazards models were used to estimate hazard ratios for all-cause mortality.Results: The patients were 72.5 ± 9.8 years old, and 47.57% were male. The median follow-up was 58 months, and the mortality rate in patients with CKD was 30.27%. A higher PNI protected against all-cause mortality in patients with CKD, with an adjusted hazard ratio (aHR) of 0.98 (95% confidence interval (CI): 0.97-0.99). After grouping according to PNI quartiles, statistically significant between-group differences were observed in survival probabilities. The aHR for the lowest PNI quartile compared to the highest PNI quartile was 1.64 (95% CI: 1.26-2.14). Sensitivity analysis further supported this association. Restricted cubic spline analysis revealed an L-shaped association between the PNI and all-cause mortality in patients with CKD, with a critical value of 50.5. CONCLUSIONS: The PNI is a protective factor in patients with CKD, with an L-shaped decrease in all-cause mortality with an increasing PNI.

[Seminal vesiculoscopy: Safe and effective for the treatment of refractory hemospermia].

OBJECTIVE: To investigate the clinical effect and safety of transutricular seminal vesiculoscopy in the treatment of refractory hemospermia. METHODS: Using 6Fr ureteroscopy through the prostatic utricle, we treated 103 cases of refractory hemospermia with distal seminal duct obstructive lesions, including 12 cases complicated by distal seminal duct cyst. We rinsed the seminal duct cavity, cleaned out the stones, removed the cyst wall with holmium laser and followed up the patients for 12 months postoperatively. RESULTS: The operations were successfully completed in all the cases but 1 (0.9%), in which the ureteroscope failed to enter the bilateral seminal vesicles. The operation time was (47 ± 9) min. No rectal injury or acute epididymitis occurred intraoperatively, nor fever, long-term dysuria or long-term hematuria after surgery. Postoperative follow-up showed that bloody semen symptoms vanished in 93 (90.3%) of the cases, improved significantly in 4 (3.9%) and not significantly in 2 (1.9%), and 3 cases of recurrence (2.9%) were all relieved after reoperation. CONCLUSION: Transutricular seminal vesiculoscopy has the advantages of clear anatomic vision, minor invasiveness and significant effectiveness in the treatment of refractory hemospermia. What's more, holmium laser is better than plasmakinetic resection in removal of the cyst wall.

MicroRNA-873 Inhibits Morphine-Induced Macrophage Apoptosis by Elevating A20 Expression.

OBJECTIVES: To study the role of microRNA-873 (miR-873) in suppressing morphine-induced macrophage apoptosis and morphine dependence, and to identify molecular targets within the miR-873 pathway for the treatment of immune suppression and morphine addiction. METHODS: As morphine elevates TLR9 expression and induces TLR9-mediated apoptosis, we used TLR9 knockout Balb/C mice to study TLR9-independent effects of miR-873 on morphine-induced macrophage apoptosis. Forty TLR9-knockout mice were randomly and equally assigned to morphine group and control group. Following the administration of morphine, miR-873 mimics or miR negative control was injected into mice in each group. Using freshly isolated macrophages from mice and RAW264.7 murine macrophage cell line, miR-873 level was determined by qRT-PCR and morphine induced apoptosis was measured by TUNEL assays. Western blotting was used to detect and quantify the expression level of A20, a protein that negatively regulates inflammation and TNF-induced apoptosis. RESULTS: qRT-PCR analysis revealed a markedly lower expression of miR-873 in freshly isolated peritoneal macrophages, liver tissue and spleen tissue in the morphine group compared with the corresponding tissues in the control group. TUNEL assays showed that the apoptosis rates in the morphine groups treated with miR-873 mimics was markedly lower than their respective control groups. Western blotting results showed that A20 expression level was sharply elevated in the experimental groups treated with miR-873 mimics than the negative and blank control groups. CONCLUSIONS: Our results show that miR-873 elevates A20 levels and inhibits morphine-induced macrophage apoptosis.

A Revolving Temporary Anchorage Cap Connecting to an Orthodontic Miniscrew Using In Vitro Experimental Testing: Safety and Biomechanical Evaluations.

PURPOSE: This study is to develop a plastic revolving (translation and rotation) temporary anchorage cap (TAC) as the orthodontic anchor and evaluate its biomechanical safety and clinical used feasibility. MATERIALS AND METHODS: The TAC was designed to connect onto a mini-implant head with 45-degree switching unit and extended arm for tying an orthodontic elastic chain/coil spring. The removal force between the TAC and mini-implant head and torque resistance on the mini-implant/bone interface were performed to evaluate the biomechanical safety. Clinical molar uprighting and mesial drive application were performed to reveal the TAC feasibility/capacity. RESULTS: The removal force was 43.95 N (>>finger-pulling force 9.3 N) to prevent the TAC from detaching, and the torque resistance was 159.25 N·mm to maintain micromotion smaller than 30.4 µm between the screw and bone. The strain value in using TAC treatment was found to be about 2 times that of traditional tracing (without using TAC) in molar uprighting/mesial drive application. CONCLUSIONS: The plastic revolving TAC can provide optional use with translation/rotation features to change the angles and directions in orthodontic tractions and increase treatment efficiency under biomechanical safety considerations.

The multi-lineage differentiation and angiogenesis ability of adipose-derived adult mesenchymal stem cells.

BACKGROUND: To investigate the in vitro multi-lineage differentiation of adipose-derived adult stem cells and their ability to differentiate into endothelial cells. METHODS: Adipose-derived adult stem cells were isolated for detection of the immune phenotype, cell doubling time, cycle, and induction of endothelial cell differentiation in vitro. The expression of endothelial cell-specific surface markers was measured immunocytochemically. RESULTS: Adipose-derived adult stem cells have multi-lineage differentiation potential and can differentiate into endothelial cells in vitro. CONCLUSIONS: Adipose-derived adult stem cells have the same differentiation ability with those derived from the bone marrow, as both can differentiate into endothelial cells. These findings have opened up the prospect of adipose-derived adult stem cells in angiogenesis therapy.

Do dual-thread orthodontic mini-implants improve bone/tissue mechanical retention?

PURPOSE: The aim of this study was to understand whether the pitch relationship between micro and macro thread designs with a parametrical relationship in a dual-thread mini-implant can improve primary stability. MATERIALS AND METHODS: Three types of mini-implants consisting of single-thread (ST) (0.75 mm pitch in whole length), dual-thread A (DTA) with double-start 0.375 mm pitch, and dual-thread B (DTB) with single-start 0.2 mm pitch in upper 2-mm micro thread region for performing insertion and pull-out testing. Histomorphometric analysis was performed in these specimens in evaluating peri-implant bone defects using a non-contact vision measuring system. RESULTS: The maximum inserted torque (Tmax) in type DTA was found to be the smallest significantly, but corresponding values found no significant difference between ST and DTB. The largest pull-out strength (Fmax) in the DTA mini-implant was found significantly greater than that for the ST mini-implant regardless of implant insertion orientation. Mini-implant engaged the cortical bone well as observed in ST and DTA types. CONCLUSION: Dual-thread mini-implant with correct micro thread pitch (parametrical relationship with macro thread pitch) in the cortical bone region can improve primary stability and enhanced mechanical retention.

Effects of an augmented reality aided system on the placement precision of orthodontic miniscrews: A pilot study.

Background/purpose: Augmented reality (AR) is gaining popularity in medical applications, which may aid clinicians in achieving improved clinical outcomes. The purpose of this study was to determine the positional and angle errors of orthodontic miniscrew placement by using a self-developed AR aided system. Materials and methods: Cone beam computed tomography (CBCT) and patient printed models were used in in vitro experiments. The participants were divided into a control group and an AR group, in which traditional orthodontic methods and the AR-aided system were used respectively. After the information obtained from the CBCT images and navigation system was combined on the display device, the AR-aided system indicated the planned miniscrew position to guide the clinicians during the placement of miniscrews. Both methods were compared by a senior and a junior dentist, and the position and angle of miniscrew placement were statistically analyzed using Wilcoxon's signed-rank and Mann-Whitney U tests. Results: When the AR-aided system was used, the accuracy of miniscrew placement in the mesiodistal position considerably increased (83%) when the procedure was performed by a senior clinician. In addition, the accuracy of miniscrew placement in the mesiodistal position and the angle of miniscrew placement considerably increased by approximately 67% and 72%, respectively, when the procedure was performed by a junior clinician. The position error of miniscrew placement was smaller for the junior clinician when the AR-aided system was used than for the senior clinician. Conclusion: The AR-aided system improved the accuracy of miniscrew placement regardless of the clinician's level of experience.

The effect of low-level laser therapy on osteoclast differentiation: Clinical implications for tooth movement and bone density.

Background/purpose: Osteoclast differentiation is crucial for orchestrating both tooth movement and the maintenance of bone density. Therefore, the current study sought to explore the impact of low-level laser therapy (LLLT) on osteoclast differentiation, functional gene expression, molecular signaling pathways, and orthodontic tooth movement in clinical settings. Materials and methods: The RAW 264.7 cell line served as the precursor for osteoclasts, and these cells underwent irradiation using a 808-nm LLLT. Osteoclast differentiation was assessed through tartrate-resistant acid phosphatase (TRAP) staining. Functional gene expression levels were evaluated using real-time quantitative polymerase chain reaction (RT-qPCR) while signaling molecules were examined through Western blot analysis. In the clinical study, 12 participants were enrolled. Their tooth movement was monitored using a TRIOS desktop scanner. Bone density measurements were conducted using Mimics software, which processed cone-beam computed tomography (CBCT) images exported in Digital Imaging and Communications in Medicine (DICOM) format. Results: We found that LLLT effectively promoted receptor activator of nuclear factor-κB ligand (RANKL)-dependent osteoclast differentiation and the expression of osteoclast functional genes, including matrix metallopeptidase 9 (MMP9), nuclear factor of activated T-cells cytoplasmic 1(NFATc1), tartrate-resistant acid phosphatase (TRAP) and cathepsin K (CTSK) in RAW264.7 cells. Clinically, the cumulative tooth movement over 90 days was significantly higher in the laser group than in the control group. Conclusion: Our research demonstrates that LLLT not only significantly promotes osteoclast differentiation but is also a valuable adjunct in orthodontic therapy.

Exploring the impact of culture techniques and patient demographics on the success rate of primary culture of human periodontal ligament stem cells.

Background/purpose: Periodontal ligament stem cells (PDLSCs) have the potential for regenerating periodontal tissue. The study aims to investigate the impact of demographics (ages, gender, disease) and culture techniques (shipping storage time and culture method) on the success of primary culture. Materials and methods: PDLSCs were collected from 51 teeth of 26 patients and cultured via outgrowth (OG) and enzymatic digestion (ED) methods. Cells characteristics were confirmed by flow cytometry, MTT, and ARS. The primary culture success rate was evaluated with a serial chi-square test to determine the relationship with culture technique (ED/OG and ≤4 h/prolonged culture) and patient demographics (Young/Old, Female/Male, and Health/Periodontitis). Results: The overall success rate of Health group (69.7%) was higher than Periodontitis (38.9%). Culturing within 4 h possessed a higher success rate (71.8%) than prolonged group (16.7%) regardless of patient demographics, and using OG method (81.5%) revealed more promising. Subgroup analysis of 39 cases (culture within 4 h) found that the success rate of OG was higher than ED in the Old group (87.5%-25.0%) and in the Periodontitis group (83.3%-25.0%). Conclusion: Primary culturing of PDLSCs within 4 h and using the outgrowth method led to higher success rates regardless of patient demographics. It can achieve successful PDLSCs culture of older patients or patients with periodontal disease by appropriate culture technique.

Biomechanical evaluation of an orthodontic miniimplant used with revolving (translation and rotation) temporary anchorage device by finite element analysis and experimental testing.

PURPOSE: To evaluate the biomechanical interactions of a miniimplant using a temporary anchorage device (TAD) for orthodontic traction. MATERIALS AND METHODS: A miniimplant was designed with dual thread (DT) with a TAD that can be connected optionally onto the miniimplant with 60-degree switching unit and an extended arm for tying orthodontic wire. Finite element analysis was used to calculate the relative miniimplant displacement and bone strain under immediate load (500 gW) on behalf of the maximum lateral force during orthodontic treatment. The TAD removal forces were measured by pullout testing. RESULTS: Simulated results showed that the maximum von Mises bone strain concentrated at the cervical regions around the miniimplant. The corresponding strain value in DT miniimplant assembled with TAD was greater than those for DT and single-thread implants with 2.24 and 1.73 times, respectively. Small relative miniimplant displacement (<20 µm) was found in all cases. The TAD removal force remained larger than 2 times the finger-pulling force (9.3 N) after 5 repeated removal tests. CONCLUSION: The DT miniimplant connected with TAD can provide translation and rotation features to change the angles and directions of orthodontic tractions for most effective anchorage preparation.

Improved super-elastic Ti-Ni alloy wire for treating adult skeletal class III with facial asymmetry: A case report.

BACKGROUND: Correcting severe skeletal class III malocclusion with facial asymmetry in adults through orthodontic treatment alone is difficult. CASE SUMMARY: In this case report, we describe orthodontic treatment and lower incisor extraction without orthognathic surgery for a 27-year-old man with a transverse discrepancy. The extraction sites were closed using an elastic chain. The use of intermaxillary elastics, improved super-elastic Ti-Ni alloy wire, and unilateral multibend edgewise arch wire was crucial for correcting facial asymmetry and the midline deviation. CONCLUSION: After treatment, the patient had a more symmetrical facial appearance, acceptable overjet and overbite, and midline coincidence. The treatment results remained stable 3 years after treatment. This case report demonstrates that a minimally invasive treatment can successfully correct severe skeletal class III malocclusion with facial asymmetry.

Improved super-elastic Ti-Ni alloy wire intrusion arch for skeletal class II malocclusion combined with deep overbite: A case report.

BACKGROUND: Treatment for deep overbite cases can be difficult. This case report presents some techniques with improved super-elastic Ti-Ni alloy wire (ISW) for deep overbite correction. CASE SUMMARY: A 21-year-old woman had a chief complaint of flaring maxillary teeth. Orthodontic evaluation revealed a skeletal class II malocclusion and a convex profile appearance. A deep overbite with palatal impingement and large overjet were also noted. Bilateral maxillary first premolars were extracted, and spaces were closed using a closed-coil spring and elastic chain. The deep overbite was corrected by applying the ISW curve and ISW intrusion arch. Intermaxillary elastics was used to adjust the intermaxillary relationship. Active treatment took approximately 3 years, and the appearance and dentition alignment noticeably improved. CONCLUSION: The use of the ISW technique in a case of skeletal class II malocclusion with deep overbite achieved a desirable result, and the patient was satisfied with the treatment outcome.

Effect of Various Airborne Particle Abrasion Conditions on Bonding between Polyether-Ether-Ketone (PEEK) and Dental Resin Cement.

The effects of alumina particle size and jet pressure on the bond strength of polyetheretherketone (PEEK) were examined to determine the airborne particle abrasion parameters with minimal effects on PEEK and to achieve optimal bond strength, as a reference for future clinical use. An alumina particle with four particle sizes and three jet pressures was used to air-abrade PEEK. Surface roughness (Ra), morphology, chemical structure, and wettability were analyzed using a stylus profilometer, scanning electron microscope, X-ray diffractometer, and contact angle analyzer, respectively. The shear bond strength (SBS) of PEEK and dental resin cement was analyzed using a universal testing machine (n = 10). The failure modes and debonded fracture surfaces were observed using optical microscopy. Airborne particle abrasion increased the Ra and hydrophobicity of PEEK and deposited alumina residues. The SBS generally decreased after thermal cycling. A large particle size damaged the PEEK surface. The effects of different particle sizes and jet pressures on the SBS were only significant in certain groups. Adhesive failure was the main mode for all groups. Within the limitations of this study, 110 µm grain-sized alumina particles combined with a jet pressure of 2 bar prevented damage to PEEK, providing sufficient SBS and bonding durability between PEEK and dental resin cement.

Effects of orthodontic tooth movement on alveolar bone density.

The object of this study was to evaluate the relationship between changes in the alveolar bone density around the teeth and the direction of tooth movement by using cone-beam computed tomography (CBCT). CBCT was used to measure the bone densities around six maxilla anterior teeth before and after 7 months of orthodontic treatment in eight patients. Each root was divided into three levels (cervical, intermediate, and apical) to determine whether the bone density change varied with the tooth level. Moreover, each level was divided into four regions (palatal, distal, mesial, and buccal sides). Three-dimensional computer models of the maxilla before and after orthodontic treatment were created to detect the direction of tooth movement. The percentage for all 144 samples [8 (patients) × 6 (teeth) × 3 (levels)] in which the side (palatal, distal, mesial, or buccal sides) of maximum bone density reduction (before and after orthodontic treatment) coincided with the direction of tooth movement was calculated; this was referred to as the "coincidence percentage". The bone density around the teeth reduced by 24.3 ± 9.5%. The average coincidence percentage for the eight patients was 59.0%. The coincidence percentages for the eight patients were 62.5%, 62.5%, and 52.1% at the cervical, intermediate, and apical levels, respectively. The obtained results demonstrate that the direction of tooth movement is associated with the side of maximum bone density reduction, and that CBCT is a useful approach for evaluating bone density changes around teeth induced by orthodontic treatment.

Risk factors for hospital readmissions in pneumonia patients: A systematic review and meta-analysis.

BACKGROUND: Factors that are associated with the short-term rehospitalization have been investigated previously in numerous studies. However, the majority of these studies have not produced any conclusive results because of their smaller sample sizes, differences in the definition of pneumonia, joint pooling of the in-hospital and post-discharge deaths and lower generalizability. AIM: To estimate the effect of various risk factors on the rate of hospital readmissions in patients with pneumonia. METHODS: Systematic search was conducted in PubMed Central, EMBASE, MEDLINE, Cochrane library, ScienceDirect and Google Scholar databases and search engines from inception until July 2021. We used the Newcastle Ottawa (NO) scale to assess the quality of published studies. A meta-analysis was carried out with random-effects model and reported pooled odds ratio (OR) with 95% confidence interval (CI). RESULTS: In total, 17 studies with over 3 million participants were included. Majority of the studies had good to satisfactory quality as per NO scale. Male gender (pooled OR = 1.22; 95%CI: 1.16-1.27), cancer (pooled OR = 1.94; 95%CI: 1.61-2.34), heart failure (pooled OR = 1.28; 95%CI: 1.20-1.37), chronic respiratory disease (pooled OR = 1.37; 95%CI: 1.19-1.58), chronic kidney disease (pooled OR = 1.38; 95%CI: 1.23-1.54) and diabetes mellitus (pooled OR = 1.18; 95%CI: 1.08-1.28) had statistically significant association with the hospital readmission rate among pneumonia patients. Sensitivity analysis showed that there was no significant variation in the magnitude or direction of outcome, indicating lack of influence of a single study on the overall pooled estimate. CONCLUSION: Male gender and specific chronic comorbid conditions were found to be significant risk factors for hospital readmission among pneumonia patients. These results may allow clinicians and policymakers to develop better intervention strategies for the patients.

Bone quality affects stability of orthodontic miniscrews.

The objective of this study was to evaluate the effect of bone-miniscrew contact percentage (BMC%) and bone quality and quantity on orthodontic miniscrew stability and the maximum insertion torque value (ITV). Orthodontic miniscrews of five different dimensions and several bovine iliac bone specimens were used in the evaluation. Miniscrews of each dimension group were inserted into 20 positions in bovine iliac bone specimens. The experiment was divided into three parts: (1) Bone quality and quantity were evaluated using cone-beam computed tomography (CBCT) and microcomputed tomography. (2) The 3D BMC% was calculated. (3) The ITVs during miniscrew insertion were recorded to evaluate the stability of the orthodontic miniscrews. The results indicated that longer and thicker miniscrews enabled higher ITVs. CBCT was used to accurately measure cortical bone thickness (r = 0.939, P < 0.05) and to predict the bone volume fraction of cancellous bone (r = 0.752, P < 0.05). BMC% was significantly influenced by miniscrew length. The contribution of cortical bone thickness to the ITV is greater than that of cancellous bone structure, and the contribution of cortical bone thickness to BMC% is greater than that of cancellous bone structure. Finally, the higher is BMC%, the greater is the ITV. This study concludes that use of CBCT may predict the mechanical stability of orthodontic miniscrews.

Evaluating the Effect of Different Polymer and Composite Abutments on the Color Accuracy of Multilayer Pre-Colored Zirconia Polycrystal Dental Prosthesis.

With increasing aesthetic awareness and emphasis on time costs in today's society, monolithic multilayer precolored zirconia ceramics (M-Zr) facilitate aesthetic restorations in a convenient and straightforward manner without the need for veneering porcelain to modify the color. However, the effect of abutment materials on the final color of M-Zr remains unclear. Herein, we placed Vita A1 Shade M-Zr on six different abutment materials, zirconia (Y-TZP), 3D printed composite resin (CR), dental model resin (MR), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), and cobalt−chromium alloy (Co−Cr), to evaluate their effect on the color accuracy of M-Zr. The color attributes (L*, a*, and b*) were measured using a dental spectrophotometer. The translucency parameter (TP), contrast ratio, color difference (ΔE) between each background substrate and the Vita A1 Shade Guide, and chroma values (C) were calculated to evaluate the color accuracy of M-Zr. A statistical analysis was performed using one-way analysis of variance and post hoc Tukey's HSD tests (α = 0.05). The experimental results indicate that the TP values and contrast ratio of the M-Zr samples were 14.85 and 0.83, respectively. Co−Cr had the highest ΔE (6.08) and lowest C value (7.52); PEKK had the lowest ΔE (2.60), and PEEK had the highest C value (12.23) (p < 0.05). Notably, the ΔE values of CR (3.13), PEEK (2.86), and PEKK were within clinical indicators (ΔE < 3.7). Based on these results, it can be concluded that the abutment material has a significant effect on the final color of the M-Zr, and PEEK or PEKK resulted in good color accuracy. When choosing the dental MR, traditional zirconia, or metals as abutment materials, colored or opaque cement might be required to eliminate color distortion and achieve desirable optical properties.

Potent Anti-SARS-CoV-2 Efficacy of COVID-19 Hyperimmune Globulin from Vaccine-Immunized Plasma.

Coronavirus disease 2019 (COVID-19) remains a global public health threat. Hence, more effective and specific antivirals are urgently needed. Here, COVID-19 hyperimmune globulin (COVID-HIG), a passive immunotherapy, is prepared from the plasma of healthy donors vaccinated with BBIBP-CorV (Sinopharm COVID-19 vaccine). COVID-HIG shows high-affinity binding to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein, the receptor-binding domain (RBD), the N-terminal domain of the S protein, and the nucleocapsid protein; and blocks RBD binding to human angiotensin-converting enzyme 2 (hACE2). Pseudotyped and authentic virus-based assays show that COVID-HIG displays broad-spectrum neutralization effects on a wide variety of SARS-CoV-2 variants, including D614G, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Kappa (B.1.617.1), Delta (B.1.617.2), and Omicron (B.1.1.529) in vitro. However, a significant reduction in the neutralization titer is detected against Beta, Delta, and Omicron variants. Additionally, assessments of the prophylactic and treatment efficacy of COVID-HIG in an Adv5-hACE2-transduced IFNAR-/- mouse model of SARS-CoV-2 infection show significantly reduced weight loss, lung viral loads, and lung pathological injury. Moreover, COVID-HIG exhibits neutralization potency similar to that of anti-SARS-CoV-2 hyperimmune globulin from pooled convalescent plasma. Overall, the results demonstrate the potential of COVID-HIG against SARS-CoV-2 infection and provide reference for subsequent clinical trials.

Bone density changes around teeth during orthodontic treatment.

The objective of this study was to evaluate bone density changes around the teeth during orthodontic treatment by using cone beam computed tomography (CBCT). CBCT was used to measure the bone densities around six teeth (both maxilla central incisors, lateral incisors, and canines) before and after 7 months of orthodontic treatment in eight patients. In addition, each root was divided into three portions (cervical, intermediate, and apical) to determine whether the bone density change varied with tooth level. The mean reduction in bone density around the measured teeth was 24% after orthodontic treatment. The bone density reduction around teeth was largest for the upper-right and upper-left central incisor (29% and 26%, respectively) and ranged from 20% to 23% for the other four teeth. The mean bone density reduction did not differ significantly between the cervical, portion, and apical portions of the teeth (26%, 22%, and 24%, respectively). CBCT is useful for evaluating bone density changes around teeth during orthodontic treatment. The bone density around the teeth reduced significantly after the application of orthodontic forces for 7 months.

Biomechanical Effect of Orthodontic Treatment of Canine Retraction by Using Metallic Orthodontic Mini-Implant (OMI) Covered with Various Angles of Revolving Cap.

OBJECTIVE: This study evaluated the biomechanical effects of a metallic orthodontic mini-implant (OMI) covered with various types of angled revolving cap on the peri-OMI bone and the canine periodontal ligament (PDL) by finite element (FE) analyses. MATERIALS AND METHODS: Three-dimensional FE models included comprised cortical bone and cancellous bone of the maxilla, and the OMIs were created. The forces (0.98 N) pulled in both the canine hook and the revolving cap, pulling towards each other in both directions as loading conditions. The upper surface of the maxilla was fixed as a boundary condition. RESULTS: The bone stresses were increasing in the models by using OMI covered with a revolving cap as compared with that in the conventional model (in which only the OMI was placed). However, no obvious differences in bone stresses were observed among the models with various types of angled revolving cap. The minimum principal strain in the canine PDL was highest for condition 180T, followed by condition 180L. However, the maximum differences in the values between each experimental model and the conventional model were around 5%. CONCLUSION: This study showed no obvious effects in decreasing or increasing stress/strain in bone and PDL by using various types of angled revolving cap covered metallic mini-implant in orthodontic treatment of canine retraction.