Long-term functional swallowing and speech outcomes after transoral robotic surgery for oropharyngeal cancer.

Objectives: Transoral robotic surgery (TORS) has emerged as a minimally invasive approach for oropharyngeal cancer, aiming to improve functional preservation and reduce morbidity. However, the long-term effects on speech and swallowing, crucial aspects of quality of life, remain unclear. This study investigates the long-term functional swallowing and speech outcomes of TORS for oropharyngeal cancer. Methods: We retrospectively reviewed 41 patients diagnosed with oropharyngeal squamous cell carcinoma who underwent TORS from 2010 to 2018. Tongue mobility, articulation, verbal diadochokinesis, reading speed, and modified barium swallowing tests were performed 2-3 years post-operatively to assess long-term speech and swallowing function. Results: The mean age was 57.7 ± 9.9 years, and the male to female ratio was 34:7. The palatine tonsil was the most common tumor site (73.2%), followed by the base of tongue (22.0%). Concurrent neck dissection was performed in 97.6% of patients, and adjuvant radiation or chemoradiation was administered to 36 patients (87.8%). Tongue mobility, articulation, verbal diadochokinesis, and reading speed were comparable to normal population. Modified barium swallowing tests revealed acceptable outcomes in most patients; only one patient (2.4%) required a percutaneous endoscopic gastrostomy tube. Notably, no permanent tracheostomies were necessary. Conclusions: Long-term speech and swallowing functions were preserved in most patients treated with TORS for oropharyngeal cancer. TORS is an excellent treatment modality for oropharyngeal cancer in terms of functional outcomes.

Six-year clinical outcomes of enzyme replacement therapy for perinatal lethal and infantile hypophosphatasia in Korea: Two case reports.

INTRODUCTION: Hypophosphatasia (HPP) is a genetic disease caused by loss-of-function mutations in ALPL, which encodes tissue-nonspecific alkaline phosphatase (ALP). Early diagnosis and treatment of perinatal and infantile HPP are important because of their high mortality rates. Enzyme replacement therapy (ERT) using human recombinant tissue-nonspecific ALP asfotase alfa was introduced in Korea in 2016. We report the first experience of ERT over 6 years for perinatal lethal and infantile HPP in Korea. PATIENT CONCERNS: The first patient was a 6-week-old Korean boy with a failure to thrive. The second patient was an 8-day-old Korean-Uzbek body with generalized tonic-clonic seizure with cyanosis. DIAGNOSES: HPP was suspected in both patients because of the very low level of ALP activity and rachitic findings on radiographs, and the disease was confirmed by Sanger sequencing of the ALPL gene. INTERVENTION: The first patient with infantile HPP started ERT at 21 months of age and the second patient with perinatal HPP started ERT at 30 days of age. Both patients received asfotase alfa (2 mg/kg 3 times per week subcutaneously, adjusted to 3 mg/kg 3 times per week if required) for 6 years. OUTCOMES: After 6 years of ERT, radiographic findings and growth standard deviation scores improved in both patients. The second patient showed no evidence of rickets after 3 years of ERT. Mechanical respiratory support and supplemental oxygen were not required after 4.5 years of treatment in the first patient and at 2 months after treatment in the second patient. CONCLUSION: Among the 2 patients, the patient who started ERT early had a much better prognosis despite a more severe initial clinical presentation. Our results suggest that early diagnosis and prompt treatment play an important role in improving long-term prognosis and avoiding morbidity and premature mortality in patients with perinatal and infantile HPP.

Case Report: Two cases of recurrences at the suprasternal space and lymph nodes between the sternocleidomastoid and sternohyoid muscles in papillary thyroid carcinoma.

Recently, lymph node metastasis to the suprasternal space (SSLN) and lymph nodes between the sternocleidomastoid and sternohyoid muscles (LNSS) have received attention. This article reports two cases of SSLN and LNSS recurrence and emphasizes the need for a thorough evaluation and consideration of the possibility of recurrence in this region. The clinical significance of the prophylactic dissection of SSLN and LNSS remains unclear, and further studies are required to determine its value. Regular follow-up checks of suspicious lymph nodes at SSLN and LNSS, as well as the central and lateral compartments, are recommended after thyroidectomy to detect recurrences and ensure appropriate management.

Feasibility of transoral robotic selective neck dissection with or without a postauricular incision for papillary thyroid carcinoma: A pilot study.

Background: The study aimed to evaluate the feasibility of transoral robotic selective neck dissection (SND) with or without a postauricular incision for papillary thyroid carcinoma (PTC). Methods: We studied 14 patients with PTC who underwent robotic SND via the transoral or combined transoral and postauricular approaches. Results: The transoral approach was performed on 10 patients for dissection of levels III and IV. An additional postauricular incision was made on 4 patients for dissection of level II in addition to levels III, IV, and V. The operation was completed successfully in 13 patients, except 1 patient with the procedure conversion due to uncontrolled bleeding from the internal jugular vein. The mean numbers of removed lymph nodes in the lateral compartment were 23.1 ± 9.4 and 38.3 ± 8.5 in the transoral and combined groups. Transient recurrent laryngeal nerve palsy occurred in 1 patient, transient hypoparathyroidism in 3 patients, and chyle leakage in 1 patient. There were no hematomas, mental nerve injuries, surgical space infections, or CO2 embolisms. Conclusion: Transoral robotic SND is feasible with or without a postauricular incision.

Biocompatibility and osteogenic potential of mineral trioxide aggregate mixed with hydrophilic synthetic polymer: An in vitro and in vivo study.

This study aimed to investigate in vitro biologic properties of mineral trioxide aggregate (MTA) mixed with 3% PVA (MTA-3% PVA) and in vivo dental pulp responses to direct capping in comparison with MTA mixed with distilled water (MTA-DW). Cell proliferation and osteogenic differentiation in culture of human dental pulp cells (hDPCs), and pH changes were evaluated. Pulps in 24 mandibular premolars of four 9-month-old beagle dogs were mechanically exposed and direct pulp capping was performed. Histological specimens were scored according to the degree of mineralization. MTA-3% PVA showed similar cell proliferation and similar or superior osteogenic differentiation of hDPCs compared with MTA-DW. All specimens were associated with calcified bridge formation and there were no significant differences in mineralization scores between the groups (p>0.05). The results suggested that MTA-3% PVA exhibited favorable biocompatibility and osteogenic differentiation in vitro compared with MTA-DW. Furthermore, both groups demonstrated similar results when used as pulp-capping agents in vivo.

Thermal Dynamics of a Novel Radio-Frequency Device for Endoscopic Spine Surgery: An Experimental Model.

STUDY DESIGN: Experimental study. OBJECTIVE: In this study, the ambient temperature of a radiofrequency (RF) electrode tip was compared and analyzed in terms of products, mode, flow quantity, and flow rate. SUMMARY OF BACKGROUND DATA: Endoscopic spine surgery is a widely used operation for degenerative lumbar stenosis and herniated lumbar disc. To perform endoscopic spine surgery, dedicated instruments like a RF generator and electrode are essential. METHODS: An evaluation system capable of measuring temperature under equal conditions at a certain distance from the electrode tip was manufactured. The distance between the electrode tip and the temperature sensor was set to 1, 5, and 10 mm. The flow quantities of 0, 50, 100, and 150 mL/min and the flow rates of 0, 0.20, 0.53, and 0.80 m/s were compared and statistically analyzed. RESULTS: The temperatures measured in the experiments conducted on the four combinations of RF device showed similar values, and showed differences according to the characteristics of each mode of the RF. As the distance between the electrode tip and the temperature sensor increased, the temperature decreased, and as flow quantity or flow rate increased, the temperature decreased. The maximum temperatures differed significantly according to flow quantity, between flow quantities of 0 and 100 mL/min (P  = 0.03) and between 0 and 150 mL/min (P ≤ 0.01). The maximum temperatures also differed significantly between the flow rate of 0 m/s, and the flow rates of 0.20, 0.53, and 0.80 m/s, with P ≤ 0.01 in all three comparisons. CONCLUSION: This is the first study in which we made a customized RF temperature evaluation system and verified the temperature changes in various environments. When irrigation was performed, we could confirm that the maximum temperature was less than 60°C. Irrigation is considered essential in endoscopic spine surgery. LEVEL OF EVIDENCE: 3.

Success rate and learning curve of intraoperative neural monitoring of the external branch of the superior laryngeal nerve in thyroidectomy.

BACKGROUND: This study aimed to evaluate the success rate and learning curve of intraoperative neural monitoring (IONM) of the external branch of the superior laryngeal nerve (EBSLN) in thyroidectomy. METHODS: We studied 130 consecutive patients (200 nerves at risk [NARs]) who had undergone conventional thyroidectomy with IONM of the recurrent laryngeal nerve (RLN) and EBSLN from January 2017 to March 2020. The learning curve was defined as the number of NARs required to achieve an effective and reliable neuromonitoring rate. RESULTS: IONM of the EBSLN was successful in 136/200 (68%) NARs. The cutoff point of the learning curve was 45 NARs (28 patients). The neural identification rate of EBSLN was significantly higher in the post-learning 155 NARs group than the pre-learning group (82.6% vs. 17.8%, p < 0.001). CONCLUSIONS: Approximately 45 NAR neuromonitoring attempts were required to reach a significant increase in the EBSLN identification rate and overcome the learning curve.

Midfacial soft tissue changes after maxillary expansion using micro-implant-supported maxillary skeletal expanders in young adults: A retrospective study.

OBJECTIVE: The aim of this retrospective study was to assess the midfacial soft tissue changes following maxillary expansion using micro-implant-supported maxillary skeletal expanders (MSEs) in young adults by cone-beam computerized tomography (CBCT) and to evaluate the correlations between hard and soft tissue changes after MSE usage. METHODS: Twenty patients (mean age, 22.4 years; range, 17.6-27.1) with maxillary transverse deficiency treated with MSEs were selected. Mean expansion amount was 6.5 mm. CBCT images taken before and after expansion were superimposed to measure the changes in soft and hard tissue landmarks. Statistical analyses were performed using paired t-test and Pearson's correlation analysis on the basis of the normality of data. RESULTS: Average lateral movement of the cheek points was 1.35 mm (right) and 1.08 mm (left), and that of the alar curvature points was 1.03 mm (right) and 1.02 mm (left). Average forward displacement of the cheek points was 0.59 mm (right) and 0.44 mm (left), and that of the alar curvature points was 0.61 mm (right) and 0.77 mm (left) (p < 0.05). Anterior nasal spine (ANS), posterior nasal spine (PNS), and alveolar bone width showed significant increments (p < 0.05). Changes in the cheek and alar curvature points on both sides significantly correlated with hard tissue changes (p < 0.05). CONCLUSIONS: Maxillary expansion using MSEs resulted in significant lateral and forward movements of the soft tissues of cheek and alar curvature points on both sides in young adults and correlated with the maxillary suture opening at the ANS and PNS.

Pharyngeal Airway Morphology in Skeletal Class III With Mandibular Asymmetry is Improved After Bimaxillary Orthognathic Surgery.

PURPOSE: The relationship between pharyngeal airway morphology and jawbone movements in skeletal Class III patients with mandibular asymmetry after orthognathic surgery remains unclear. This study was to measure the changes in pharyngeal airway morphology in skeletal Class III patients with mandibular asymmetry after bimaxillary surgery and evaluate associations between changes in pharyngeal airway morphology and skeletal movements. METHODS: In this retrospective cohort study, skeletal Class III patients who underwent bimaxillary surgery were enrolled. The predictor variable was facial symmetry status divided into 2 groups, asymmetric (Group A) and symmetric (Group B). The primary outcome variables were changes in airway parameters, including cross-sectional linear distances, cross-sectional area (CSA), minimum CSA (Min-CSA), and volume; and airway asymmetry index between the preoperative and 6-month postoperative imaging studies. Correlation analysis was performed between upper airway and skeletal changes. RESULTS: Twenty-five patients were included in this study, with 15 patients in Group A (mean age: 23.00 years; BMI: 22.83) and 10 patients in Group B (mean age: 22.30 years; BMI: 22.48). Group A showed a higher asymmetry index than Group B at T0; however, no significant differences compared to Group B at T1. The airway volume was significantly decreased in the oropharynx in Group A at T1, whereas it showed no significant differences in Group B (P < .05). Lateral movement of B point and Menton showed positive correlations with changes in Min-CSA in the oropharynx and negative correlations with changes in airway asymmetry index (P < .05). CONCLUSIONS: Pharyngeal airway exhibited an asymmetrical and constricted morphology in Group A before surgery. The airway morphology in Group A showed a tendency to adopt a symmetrical and less constricted shape after surgery. The airway space was reduced in the oropharynx in Group A after surgery. Surgical correction of mandibular asymmetry correlated with the improvement of pharyngeal airway morphology.

Comparative Analysis of Root Canal Filling Debris and Smear Layer Removal Efficacy Using Various Root Canal Activation Systems during Endodontic Retreatment.

The complete removal of obturation material can be a challenge in nonsurgical root canal retreatment. The insufficient removal of obturation material is a reason for root canal retreatment failure. The purpose of this study was to assess the efficacy of different final root canal irrigation activation methods in removing debris and smear layers in the apical and middle portions of root canals during retreatment. Sixty-six distal roots of freshly extracted molars were randomly divided into six groups: (1) primary root canal treatment with no obturation (negative control); (2) retreatment with only conventional instrumentation and irrigation (positive control); (3) retreatment with additional ultrasonic irrigation using the Piezon Master 700; (4) ultrasonic irrigation with the ENDOSONIC Blue; (5) sonic irrigation with the EDDY; and (6) multisonic irrigation with the GentleWave system. Roots were split and prepared for scanning electron microscopic (SEM) evaluation. Acquired images were assessed to quantify the amount of debris and smear remaining. Among the treatment groups, Group 6 had a significantly lower debris score than Group 2 (positive control) in both the middle and apical regions (p = 0.004, p = 0.012). All treatment groups showed significantly lower smear scores than Group 2 in the middle and apical regions (p < 0.05). The GentleWave multisonic System showed a more optimal cleaning efficacy of the root canal debris but did not differ significantly with the tested passive ultrasonic or sonic irrigation method.

Main and Accessory Canal Filling Quality of a Premixed Calcium Silicate Endodontic Sealer According to Different Obturation Techniques.

The present study aimed to investigate the effects of different obturation techniques on the main and accessory canal filling quality of a premixed calcium silicate endodontic sealer (Endoseal TCS). We also highlighted the validity of the methods used for evaluating the canal filling quality. Thirty single-rooted premolars were used for the main canal filling and 75 were used for accessory canal filling. The canals were instrumented and randomly divided into three groups according to the filling techniques: (1) single-cone technique (SC), (2) single-cone with ultrasonic activation (SU), and (3) warm vertical compaction (WV). Voids in relation to the root canal fillings were assessed using cross-section images from microcomputed tomography (µCT) scans or transversely sectioned tooth specimens (n = 10). After demineralization and clearing of the teeth, the incidence, number, and completeness of the accessory canal fillings were evaluated (n = 25). One-way analysis of variance (ANOVA) and Tukey's post hoc test was used for the evaluation of the voids in the main root canal and the incidence and number of filled accessory canals. Pearson's chi-squared (χ2) test was used for the evaluation of the filling completeness (α = 0.05). In the stereomicroscopic evaluation of the sectioned specimen, the SC group had significantly higher void occurrence than the other groups (p < 0.05), although there was no difference between groups in the µCT evaluation. However, there was no difference between the SU and WV. There was no difference between all the groups regarding the incidence, number, and completeness of the accessory canal fillings. When the premixed calcium silicate sealer is used with SC, the ultrasonic activation is recommended to obtain a better main canal filling quality. In contrast, the obturation techniques did not affect the accessory canal filling. We also recommend using the sectioning method when the void formation in the root canal filling materials is evaluated.

Ovarian pregnancy rupture in second trimester manifesting mental change in pregnancy: a case report.

Ovarian pregnancies comprise approximately 3% of ectopic pregnancies. Moreover, ovarian pregnancies in the second trimester are extremely rare. We herein present a case of ruptured ovarian pregnancy in the second trimester. A 26-year-old Asian woman presented to our hospital complaining of an abrupt mental change. She was pregnant; however, she had not been receiving antenatal care. Her initial vital signs were unstable, and pelvic ultrasound revealed pelvic fluid collection. We analyzed the hemoperitoneum and performed exploratory laparotomy. When her abdomen was opened, we observed that her right ovary was ruptured. Placental cord insertion originated from the ovary, and a fetus was found in the pelvic cavity. The ovarian pregnancy was detected in a delayed state. Pregnant women require appropriate antenatal care, and pelvic ultrasound should be performed in the second trimester to ensure that the fetus is in the intrauterine cavity.

Comparative Analysis of Biofilm Removal Efficacy by Multisonic Ultracleaning System and Passive Ultrasonic Activation.

The purpose of this study was to compare disinfection and the biofilm removal efficacy of the GentleWave System (Sonendo, Inc., Laguna Hills, CA, USA) with passive ultrasonic activation method. Forty-seven freshly extracted human molars were inoculated with Enterococcus faecalis and cultured for five weeks to establish biofilm. Eight molars were tested for confirmation of infection. Four of the eight teeth were not inoculated in order to provide a negative control. The remaining 39 inoculated molars were randomly separated into three treatment groups (n = 13 per group): Group 1-no treatment, Group 2-conventional rotary instrumentation and passive ultrasonic activation, and Group 3-minimal instrumentation and the GentleWave System treatment. Roots were subsequently prepared per standard histological tissue processing procedures. Modified Brown and Brenn stained sections and Hematoxylin and Eosin stained sections were visualized at 4× and 13.5× magnification using a stereomicroscope. The sections were scored and blindly analyzed by two independent evaluators, including a histopathologist, to evaluate the presence of biofilm on canal wall. A significant difference was found between Group 2 and Group 3 in both apical and middle regions (p = 0.001) of the mesial roots of mandibular molars and mesiobuccal roots of maxillary molars. Group 3 revealed significantly less biofilm than the controls (p = 0.003). The GentleWave System demonstrated significantly greater reduction in biofilm within the mesial roots of mandibular molars and mesiobuccal roots of maxillary molars than those treated with conventional rotary instrumentation and passive ultrasonic activation protocol.

Synthesis of a Ca3 SiO5 -Ca2 SiO4 -Ca3 Al2 O6 cement system with rapid setting capacity by spray-pyrolysis coupled with sol-gel method.

A modified mineral-trioxide-aggregate (mMTA) with rapid setting capacity was newly synthesized by spray-pyrolysis following a sol-gel reaction. Its faster setting capacity and initially higher compressive strength compared with Portland cement (PC) were evaluated. The precursor solution of the mMTA was prepared through condensation following hydrolysis among Ca(NO3 )2 ·4H2 O, Si(OC2 H5 )4 , and Al(NO3 )3 ·9H2 O under nitric acid. The mMTA powder was then synthesized by spray-pyrolysis at 1500°C. The particle shape was spherical with an average particle size of 0.8 ± 0.3 µm, while PC particles were irregular and 3.9 ± 3.0 µm in size. The mMTA consisted of mostly Ca3 SiO5 , Ca3 Al2 O6 , and partial Ca2 SiO4 phases, while the PC comprised mainly Ca3 SiO5 , Ca2 SiO4 , and partial Ca3 Al2 O6 phases. The final setting times of mMTA and PC measured under 95% relative humidity were about 11 min and 3 h, respectively. The early stage of setting in mMTA was dominated by the rapid formation of hexagonal-plate-like Ca3 Al2 O6 ·6H2 O crystals, while that in PC was dominated by needle-like calcium-silicate-hydrate gels and columnar-shaped Ca(OH)2 crystals. The late stage of setting in mMTA was dominated by calcium-silicate-hydrate gels and Ca(OH)2 crystals, while that in PC was dominated by Ca3 Al2 O6 ·6H2 O crystals. The compressive strengths of mMTA and PC after 30 min of setting were 4.5 and 0.2 MPa, respectively. The results suggest that mMTA has potential to be used as a filling material for accidental pulp-exposure or pulpal floor perforation cases that require rapid setting capacity and initial good strength. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1440-1451, 2019.

Relationship Between Aggravation of Seizures and Methylphenidate Treatment in Subjects with Attention-Deficit/Hyperactivity Disorder and Epilepsy.

OBJECTIVES: We aimed to investigate the effectiveness and safety of methylphenidate (MPH), and especially its influence on seizures, in subjects with attention-deficit/hyperactivity disorder (ADHD) and epilepsy through a retrospective chart review of subjects treated with MPH in a clinical setting. We also evaluated factors that could affect seizure aggravation during MPH treatment. METHODS: From April 2004 to July 2011, MPH was prescribed to 105 subjects with ADHD and epilepsy. The demographic characteristics, psychiatric and medical history, and electroencephalography (EEG) results were reviewed. Two pediatric neurologists reviewed seizure type, epilepsy diagnosis, changes in seizure frequency, and EEG parameters during MPH treatment. Pediatric neurologists and psychiatrists determined the temporal relationship between seizure aggravation and MPH treatment. RESULTS: The mean age of the subjects was 14.8 ± 3.4 years (range: 7-24 years). Sixty-five (61.9%) of the subjects were male. The mean duration of MPH treatment was 22 months (range: 2 weeks to 89 months) and the mean dose of MPH was 0.84 mg/kg/day. MPH was effective in controlling ADHD symptoms in both the seizure aggravation and nonaggravation groups. However, 21 (20%) subjects had aggravated seizures and 32 (32.3%) subjects had worsened EEG findings. Subjects with uncontrolled seizure or anxiety disorders at baseline were more likely to show aggravated seizures. Subjects who had epileptiform discharges, anxiety disorders, or were free of antiepileptic drug use at baseline experienced EEG worsening more frequently. The median duration of MPH treatment was significantly longer in subjects who did not show seizure aggravation than in those who did (p < 0.001). CONCLUSIONS: MPH treatment may be related to aggravation of seizures or significant worsening of EEG findings in subjects with ADHD and epilepsy. Thus, clinicians should closely monitor seizure aggravation after MPH administration, especially for high-risk subjects with uncontrolled seizures or anxiety disorders at baseline.

Preparation of fluoride-loaded microcapsules for anticariogenic bacterial growth using a coaxial ultrasonic atomizer.

A new method to deliver fluoride using biodegradable poly(lactic-co-glycolic acid) microcapsules to suppress cariogenic bacterial growth during orthodontic treatment was investigated. A coaxial ultrasonic atomizer was used to encapsulate KF solution into microcapsules. The orthodontic adhesive resin disk containing fluoride loaded microcapsules (DFLM) was prepared by LED light curing. The microstructure of microcapsules, successful loading of KF, fracture strength, and shear bonding strength were assessed by FE-SEM, confocal laser scanning microscope, and general purpose testing machine, respectively. Fluoride release from the DFLM in phosphate buffered saline and pH changes were measured after different periods of soaking time. Antibacterial activity of the DFLM was assessed in tryptic soy broth containing mutant streptococci. The starting inoculum and the orthodontic resin disk containing microcapsules not loaded with KF were used as negative and positive controls, respectively. As results, the cumulative amount of KF after 49 days was about 85% of the initial amount of fluoride contained in the microcapsules. The fracture and shear bonding strengths of the orthodontic resin disks with and without the microcapsules were similar to each other. The DFLM showed lower bacterial growth than the control groups, whereas no statistically significant differences were found between the negative and positive controls. It can be concluded that the microcapsules loaded with fluoride prepared by a coaxial ultrasonic atomizer have good potential for application as an antibacterial agent due to their excellent cariogenic antibacterial activity when incorporated into orthodontic adhesive resin. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 31-39, 2018.

Does stabilization of the degenerative lumbar spine itself produce multifidus atrophy?

The effect of stabilization of the degenerative segment on changes in the pattern of paraspinal muscle activity was investigated using a previously developed musculoskeletal model. Muscle activity change depending on L4-L5 segment stabilization with and without taking into account the presence of multifidus atrophy according to direct invasion of the back muscle during surgery (MADIBM) was analysed in erect standing and 20° flexed postures. For the stabilization of the degenerative segment, a fusion or non-fusion stabilization with a pedicle-based dynamic stabilization system (PBDS) was applied. During erect standing, fusion generated a 12% reduction in the total multifidus muscle force, while its reduction was 6.6% with PBDS application. The presence of MADIBM produced 23.0% and 22.5% reductions in fusion and with PBDS application, respectively. During 20° flexion, 10.5% and 9.3% reductions were produced for fusion and PBDS application, respectively, and the corresponding values were 23.4% and 23.0%, respectively, in the presence of MADIBM. Increased facet joint contact forces were produced at the non-stabilized levels after stabilization while in erect standing posture. Alterations in muscle activity, which could be regarded as adaptions to altered spinal stability, may generate unexpected secondary problems in the spine.

Effect of lumbar fasciae on the stability of the lower lumbar spine.

The biomechanical effect of tensioning the lumbar fasciae (LF) on the stability of the spine during sagittal plane motion was analysed using a validated finite element model of the normal lumbosacral spine (L4-S1). To apply the tension in the LF along the direction of the fibres, a local coordinate was allocated using dummy rigid beam elements that originated from the spinous process. Up to 10 Nm of flexion and 7.5 Nm of extension moment was applied with and without 20 N of lateral tension in the LF. A follower load of 400 N was additionally applied along the curvature of the spine. To identify how the magnitude of LF tension related to the stability of the spine, the tensioning on the fasciae was increased up to 40 N with an interval of 10 N under 7.5 Nm of flexion/extension moment. A fascial tension of 20 N produced a 59% decrease in angular motion at 2.5 Nm of flexion moment while there was a 12.3% decrease at 10 Nm in the L5-S1 segment. Its decrement was 53 and 9.6% at 2.5 Nm and 10 Nm, respectively, in the L4-L5 segment. Anterior translation was reduced by 12.1 and 39.0% at the L4-L5 and L5-S1 segments under 10 Nm of flexion moment, respectively. The flexion stiffness shows an almost linear increment with the increase in fascial tension. The results of this study showed that the effect of the LF on the stability of the spine is significant.

Comparison of mechanical and biological properties of zirconia and titanium alloy orthodontic micro-implants.

OBJECTIVE: The aim of this study was to compare the initial stability as insertion and removal torque and the clinical applicability of novel orthodontic zirconia micro-implants made using a powder injection molding (PIM) technique with those parameters in conventional titanium micro-implants. METHODS: Sixty zirconia and 60 titanium micro-implants of similar design (diameter, 1.6 mm; length, 8.0 mm) were inserted perpendicularly in solid polyurethane foam with varying densities of 20 pounds per cubic foot (pcf), 30 pcf, and 40 pcf. Primary stability was measured as maximum insertion torque (MIT) and maximum removal torque (MRT). To investigate clinical applicability, compressive and tensile forces were recorded at 0.01, 0.02, and 0.03 mm displacement of the implants at angles of 0°, 10°, 20°, 30°, and 40°. The biocompatibility of zirconia micro-implants was assessed via an experimental animal study. RESULTS: There were no statistically significant differences between zirconia micro-implants and titanium alloy implants with regard to MIT, MRT, or the amount of movement in the angulated lateral displacement test. As angulation increased, the mean compressive and tensile forces required to displace both types of micro-implants increased substantially at all distances. The average bone-to-implant contact ratio of prototype zirconia micro-implants was 56.88 ± 6.72%. CONCLUSIONS: Zirconia micro-implants showed initial stability and clinical applicability for diverse orthodontic treatments comparable to that of titanium micro-implants under compressive and tensile forces.

Evaluation of the safety and efficiency of novel metallic implant scaler tips manufactured by the powder injection molding technique.

BACKGROUND: Although many studies have compared the properties of ultrasonic scaling instruments, it remains controversial as to which is most suitable for implant scaling. This study evaluated the safety and efficiency of novel metallic ultrasonic scaler tips made by the powder injection molding (PIM) technique on titanium surfaces. METHODS: Mechanical instrumentation was carried out using four types of metal scaler tips consisting of copper (CU), bronze (BR), 316 L stainless steel (316 L), and conventional stainless steel (SS) tips. The instrumented surface alteration image of samples was viewed with scanning electron microscope (SEM) and surface profile of the each sample was investigated with confocal laser scanning microscopy (CLSM). Arithmetic mean roughness (Ra) and maximum height roughness (Rmax) of titanium samples were measured and dissipated power of the scaler tip was estimated for scaling efficiency. RESULTS: The average Ra values caused by the 316 L and SS tip were about two times higher than those of the CU and BR tips (p < 0.05). The Rmax value showed similar results. The efficiency of the SS tip was about 3 times higher than that of CU tip, the 316 L tip is about 2.7 times higher than that of CU tip, and the BR tip is about 1.2 times higher than that of CU tip. CONCLUSIONS: Novel metallic bronze alloy ultrasonic scaler tip minimally damages titanium surfaces, similar to copper alloy tip. Therefore, this bronze alloy scaler tip may be promising instrument for implant maintenance therapy.