Cephalometric predictors of long-term stability in the early treatment of class III malocclusion

The aim of this study was to examine the differences in the early craniofacial morphology of Class III malocclusions. Lateral cephalograms of 45 subjects with a Class III malocclusion and an anterior crossbite in the deciduous or mixed dentition were examined before treatment, after treatment, and during the long-term retention stage. The anterior crossbites of all patients were corrected after a series of orthodontic treatments. After a mean follow-up period of 5.7 years, all the subjects were reevaluated and divided into three groups according to the final occlusal status: good, fair, and poor occlusal stability. Twenty cephalometric variables on the pretreatment lateral cephalograms were analyzed by one-way analysis of variance and discriminant analysis to identify the key determinants for discriminating among the three groups. Among the 20 variables, 11 showed statistical significance. Generally, the subjects with a smaller gonial angle and a more hypodivergent skeletal pattern had good prognosis after the early treatment of Class III malocclusion. When the AB to mandibular plane angle and N-perpendicular to point A were selected in discriminant analysis, the AB to mandibular plane angle was the most significant variable. Discriminant analysis showed a relatively high degree of correct classifications of the patients with early Class III malocclusion. In particular, discriminant analysis showed the highest accuracy (93.3%) when predicting a poor prognosis.This study was supported by a grant from the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (03- PJ1-PG1-CH09-0001)

Dentofacial characteristics of women with oversized mandible and temporomandibular joint internal derangement

Introduction: To analyze dentofacial characteristics of temporomandibular joint internal derangement (TMJ ID) in orthodontic patients with oversized mandible (skeletal Class III pattern). Materials and Methods: The sample consisted of 66 women whose mandibular body length to anterior cranial base ratio is greater than 1.12. They were divided into three groups based on magnetic resonance images of bilateral TMJs: bilateral normal disk position (BN), bilateral disk displacement with reduction (DDR), and bilateral disk displacement without reduction (DDNR). Thirty-five cephalometric variables regarding their lateral cephalograms were analyzed by Kruskal-Wallis test to evaluate differences in dentofacial morphology among the three groups. Results: Subjects with TMJ ID had a clockwise rotation of the ramus, with backward position of mandible, labial tipping of mandibular incisors, and protrusion of upper and lower lips. However, TMJ ID did not significantly influence vertical skeletal relationships. Most of the significant dentofacial changes were found between BN and DDR, and dentofacial changes between DDR and DDNR were minimal. Conclusions: This study suggests that dentofacial changes associated with TMJ ID begin to appear when TMJ ID develops to DDR from BN in patients with oversized mandible. (Angle Orthod. 2011;81:469-477.)

Effects of Electrode Position on Spatiotemporal Auditory Nerve Fiber Responses: A 3D Computational Model Study

A cochlear implant (CI) is an auditory prosthesis that enables hearing by providing electrical stimuli through an electrode array. It has been previously established that the electrode position can influence CI performance. Thus, electrode position should be considered in order to achieve better CI results. This paper describes how the electrode position influences the auditory nerve fiber (ANF) response to either a single pulse or low- (250 pulses/s) and high-rate (5,000 pulses/s) pulse-trains using a computational model. The field potential in the cochlea was calculated using a three-dimensional finite-element model, and the ANF response was simulated using a biophysical ANF model. The effects were evaluated in terms of the dynamic range, stochasticity, and spike excitation pattern. The relative spread, threshold, jitter, and initiated node were analyzed for single-pulse response; and the dynamic range, threshold, initiated node, and interspike interval were analyzed for pulse-train stimuli responses. Electrode position was found to significantly affect the spatiotemporal pattern of the ANF response, and this effect was significantly dependent on the stimulus rate. We believe that these modeling results can provide guidance regarding perimodiolar and lateral insertion of CIs in clinical settings and help understand CI performance

Enhancement of phase separation in the InGaN layer for self-assembled In-rich quantum dots

The enhancement of phase separation in the InGaN layer grown on a GaN layer with a rough surface was investigated for the formation of self-assembled In-rich quantum dots(QDs) in the InGaN layer. Transmission electron microscopy images showed that In-rich QDs with a size of 2–5 nm were formed even in an InGaN layer with a low indium content, and a layer thickness less than the critical thickness. The room-temperature photoluminescence(PL) spectrum of this layer showed emission peaks corresponding to In-rich QDs. The temperature-dependent PL spectra showed dominant peak shifts to the lower energy side, indicating that the self-assembled In-rich QDs are formed in the InGaN layer grown on a rough GaNsurface and that the carriers are localized in In-rich QDs

Benefit From Directional Microphone Hearing Aids: Objective and Subjective Evaluations

ObjectivesThe aims of this study were to find and compare the effect of directional (DIR) processing of two different hearing aids via both subjective and objective methods, to determine the association between the results of the subjective and objective evaluations, and to find out individual predictive factors influencing the DIR benefit.MethodsTwenty-six hearing aid users fitted unilaterally with each two different experimental hearing aid performed modified Korean Hearing in Noise Test (K-HINT) in three DIR conditions; omnidirectional (OMNI) mode, OMNI plus noise reduction feature, fixed DIR mode. In order to determine benefits from DIR benefit within a hearing aid and compare performance of the DIR processing between hearing aids, a subjective questionnaire was administrated on speech quality (SQ) and discomfort in noise (DN) domain. Correlation analysis of factors influencing DIR benefit was accomplished.ResultsBenefits from switching OMNI mode to DIR mode within both hearing aids in K-HINT were about 2.8 (standard deviation, 3.5) and 2.1 dB SNR (signal to ratio; SD, 2.5), but significant difference in K-HINT results between OMNI and OMNI plus noise reduction algorithm was not shown. The subjective evaluation resulted in the better SQ and DN scores in DIR mode than those in OMNI mode. However, the difference of scores on both SQ and DN between the two hearing aids with DIR mode was not statistically significant. Any individual factors did not significantly affect subjective and objective DIR benefits.ConclusionDIR benefit was found not only in the objective measurement performed in the laboratory but also in the subjective questionnaires, but the subjective results was failed to have significant correlation with the DIR benefit obtained in the K-HINT. Factors influencing individual variation in perceptual DIR benefit were still hard to explain

Outcomes of Endoscopic Tympanoplasty for Large Perforations: A Multicenter Retrospective Study in South Korea

Objectives. Endoscopic tympanoplasty (ET) provides minimally invasive transcanal access to the middle ear and improves middle ear visibility for the treatment of tympanic membrane (TM) perforations. However, the literature on surgical outcomes for large TM perforations is lacking and limited to small series. This study aimed to evaluate the clinical benefits of ET for large TM perforations. Methods. This retrospective cohort study was conducted at nine tertiary referral hospitals in South Korea, where 252 patients who underwent ET as primary surgery from September 2019 to August 2021 were included. The outcome measures included the graft success rate and pre- and postoperative audiometric data. Results. In 239 patients, the graft success rate of ET for large or subtotal perforations was 86.2% (206 patients), while the graft failure rate was 13.8% (33 patients). The graft failure rate was directly correlated with surgical techniques, including overlay and medial or lateral underlay tympanoplasty (P=0.027). Lateral underlay tympanoplasty showed the most favorable results. Sex, laterality, etiology, site and size of perforation, operation time, and graft materials did not vary significantly between the graft success and failure groups (P>0.05). The mean air-bone gap (ABG) improved significantly in both groups (graft success group: 10.0±0.6 dB and graft failure group: 7.7±0.3 dB; P<0.001). However, the ABG improvement did not significantly differ between the groups. Analysis of covariance revealed that the postoperative 500-Hz bone conduction threshold improved after successful ET (adjusted coefficient, –11.351; 95% confidence interval, –21.491 to –1.212; P=0.028). Conclusion. This study involved the largest population to date of large TM perforations treated by ET. The study findings suggest that ET is feasible and effective in treating large TM perforations

Effect of Bee Venom Acupuncture on Oxaliplatin-Induced Cold Allodynia in Rats

Oxaliplatin, a chemotherapy drug, often leads to neuropathic cold allodynia after a single administration. Bee venom acupuncture (BVA) has been used in Korea to relieve various pain symptoms and is shown to have a potent antiallodynic effect in nerve-injured rats. We examined whether BVA relieves oxaliplatin-induced cold allodynia and which endogenous analgesic system is implicated. The cold allodynia induced by an oxaliplatin injection (6 mg/kg, i.p.) was evaluated by immersing the rat’s tail into cold water (4°C) and measuring the withdrawal latency. BVA (1.0 mg/kg, s.c.) at Yaoyangguan (GV3), Quchi (LI11), or Zusanli (ST36) acupoints significantly reduced cold allodynia with the longest effect being shown in the GV3 group. Conversely, a high dose of BVA (2.5 mg/kg) at GV3 did not show a significant antiallodynic effect. Phentolamine (α-adrenergic antagonist, 2 mg/kg, i.p.) partially blocked the relieving effect of BVA on allodynia, whereas naloxone (opioid antagonist, 2 mg/kg, i.p.) did not. We further confirmed that an intrathecal administration of idazoxan (α2-adrenergic antagonist, 50 μg) blocked the BVA-induced anti-allodynic effect. These results indicate that BVA alleviates oxaliplatin-induced cold allodynia in rats, at least partly, through activation of the noradrenergic system. Thus, BVA might be a potential therapeutic option in oxaliplatin-induced neuropathy