Coronectomy of deeply impacted lower third molar : incidence of outcomes and complications after one year follow-up

Objectives: The purpose of present study was to assess the surgical management of impacted third molar with proximity to the inferior alveolar nerve and complications associated with coronectomy in a series of patients undergoing third molar surgery. Material and Methods: The position of the mandibular canal in relation to the mandibular third molar region and mandibular foramen in the front part of the mandible (i.e., third molar in close proximity to the inferior alveolar nerve [IAN] or not) was identified on panoramic radiographs of patients scheduled for third molar extraction. Results: Close proximity to the IAN was observed in 64 patients (35 females, 29 males) with an impacted mandibular third molar. Coronectomy was performed in these patients. The most common complication was tooth migration away from the mandibular canal (n = 14), followed by root exposure (n = 5). Re-operation to remove the root was performed in cases with periapical infection and root exposure. Conclusions: The results indicate that coronectomy can be considered a reasonable and safe treatment alternative for patients who demonstrate elevated risk for injury to the inferior alveolar nerve with removal of the third molars. Coronectomy did not increase the incidence of damage to the inferior alveolar nerve and would be safer than complete extraction in situations in which the root of the mandibular third molar overlaps or is in close proximity to the mandibular canal

Physics of ultrasonic wave propagation in bone and heart characterized using Bayesian parameter estimation

This Dissertation explores the physics underlying the propagation of ultrasonic waves in bone and in heart tissue through the use of Bayesian probability theory. Quantitative ultrasound is a noninvasive modality used for clinical detection, characterization, and evaluation of bone quality and cardiovascular disease. Approaches that extend the state of knowledge of the physics underpinning the interaction of ultrasound with inherently inhomogeneous and isotropic tissue have the potential to enhance its clinical utility. Simulations of fast and slow compressional wave propagation in cancellous bone were carried out to demonstrate the plausibility of a proposed explanation for the widely reported anomalous negative dispersion in cancellous bone. The results showed that negative dispersion could arise from analysis that proceeded under the assumption that the data consist of only a single ultrasonic wave, when in fact two overlapping and interfering waves are present. The confounding effect of overlapping fast and slow waves was addressed by applying Bayesian parameter estimation to simulated data, to experimental data acquired on bone-mimicking phantoms, and to data acquired in vitro on cancellous bone. The Bayesian approach successfully estimated the properties of the individual fast and slow waves even when they strongly overlapped in the acquired data. The Bayesian parameter estimation technique was further applied to an investigation of the anisotropy of ultrasonic properties in cancellous bone. The degree to which fast and slow waves overlap is partially determined by the angle of insonation of ultrasound relative to the predominant direction of trabecular orientation. In the past, studies of anisotropy have been limited by interference between fast and slow waves over a portion of the range of insonation angles. Bayesian analysis estimated attenuation, velocity, and amplitude parameters over the entire range of insonation angles, allowing a more complete characterization of anisotropy. A novel piecewise linear model for the cyclic variation of ultrasonic backscatter from myocardium was proposed. Models of cyclic variation for 100 type 2 diabetes patients and 43 normal control sub jects were constructed using Bayesian parameter estimation. Parameters determined from the model, specifically rise time and slew rate, were found to be more reliable in differentiating between sub ject groups than the previously employed magnitude parameter

The dependence of ultrasound velocity and attenuation on the material properties of cancellous bone.

There is an increasing interest in evaluating the role of ultrasound in the identification and management of osteoporosis. We may measure the velocity of ultrasound through bone and the frequency-dependent attenuation, generally referred to as broadband ultrasound attenuation (BUA). The dependence of these parameters upon osteoporotic changes in density and architecture(total loss or thinning of trabeculae width) is still not well defined. A physical model for cancellous bone was developed by introducing an array of cylindrical voids of defined diameter and configuration into polymethylmethacrylate (Perspex). Experimental studies on the cancellous bone model demonstrated that the relationship between BUA and porosity is approximately parabolic, with low BUA values obtained at both low (cortical bone) and high (bone marrow) porosities. This explains the discrepancies in the correlation between BUA and density for different bone structures reported in the literature. BUA was also found to be dependent on the number of pores and the pore distribution(structure). Velocity was found to be dependent on pore size only. BUA and velocity were also found to be temperature dependent. Permeability provides quantitative information related to structure, validated using the perspex model.In vitro studies were carried out on bovine and human cancellous bone (calcaneus and vertebrae). The relationship between Young's modulus, strength and density followed the power law predicted by theoretical models. Measurements on bovine and vertebrae samples were carried out in three orthogonal directions. Young's modulus, strength, BUA, velocity and permeability were shown to be direction dependent and hence dependent upon structure. The relationship between BUA and density followed the parabolic trend observed in the physical model, with the human samples on the rising phase and the bovine on the falling phase of the parabola. BUA in the calcaneus was found to follow a power law relationship with density (BUA = rho[1.99]). BUA was a goodpredictor of strength in both the bovine (R[2] = 74%) and calcaneus (R[2] = 75%) samples. Velocity was a good predictor of both Young's modulus and strength whenapplied to the bar wave equation (E = V[2]rho) with an R[2] of 94% and 88% respectively for the calcaneus and 91% and 92% respectively for the bovine samples. For thecalcaneus samples an R[2] of 83% and 80% for Young's modulus and strength were obtained when density in the bar wave equation was substituted by BUA. The cortical end plates have a significant offset effect on BUA in the calcaneus. Permeability was highly correlated to strength. BUA and velocity were shown to be good predictors of cancellous bone strength in vitro. Future work should concentrate upon the investigation of controlled structural models of cancellous bone and also on the extrapolation of this study to the in vivo prediction of bone strength

A review on quantitative ultrasound of fast and slow waves

Offering inexpensive, widely available and safe method to evaluate the bone condition as a prevention step to predict bone fracture which caused by Osteoporosis disease makes ultrasound becomes an alternative method beside X-ray based bone densitometry. Conventional quantitative ultrasound (QUS) applies the analysis of attenuation and velocity to estimate bone health with several measurement techniques which analyzes different types of ultrasound waves and bones. However, most of the QUS results still does not match the accuracy of the Dual X-ray absorptiometry due to the interaction of ultrasound and bone microstructure are not fully exploited. The Biot’s theory has predicted that, porous medium like a cancellous bone supporting two types of longitudinal wave known as fast and slow wave which depends on the type of medium travelled. Both experiment and simulation were conducted to investigate the correlation of fast and slow waves individually with a variety of cancellous bone condition. Some of the analysis methods are based on conventional QUS methods. The fast and slow wave relates more to the microstructure of the cancellous bone compared to overall waves. In addition, overall waves had been proven to consist of fast and slow wave and can be separated using Bayesian methods. Overall waves also found to suffer artifact such as phase cancellation and negative dispersion that could cause confusion in analyzing the parameters of ultrasound wave with bone structure. In vivo application based on fast and slow wave analysis is able to produce results based on mass density which can be compared directly and have high correlation with X-ray based bone densitometry. The recent backscattered simulation result indicates that, fast and slow waves can be reflected inside the cancellous bone might offer a new method to evaluate bone especially in crucial skeletal parts

Detection of osteoporosis in lumbar spine [L1-L4] trabecular bone: a review article

The human bones are categorized based on elemental micro architecture and porosity. The porosity of the inner trabecular bone is high that is 40-95% and the nature of the bone is soft and spongy where as the cortical bone is harder and is less porous that is 5 to 15%. Osteoporosis is a disease that normally affects women usually after their menopause. It largely causes mild bone fractures and further stages lead to the demise of an individual. This analysis is on the basis of bone mineral density (BMD) standards obtained through a variety of scientific methods experimented from different skeletal regions. The detection of osteoporosis in lumbar spine has been widely recognized as a promising way to frequent fractures. Therefore, premature analysis of osteoporosis will estimate the risk of the bone fracture which prevents life threats. This paper focuses on the advanced technology in imaging systems and fracture probability analysis of osteoporosis detection. The various segmentation techniques are explored to examine osteoporosis in particular region of the image and further significant attributes are extracted using different methods to classify normal and abnormal (osteoporotic) bones. The limitations of the reviewed papers are more in feature dimensions, lesser accuracy and expensive imaging modalities like computed tomography (CT), magnetic resonance imaging (MRI), and DEXA. To overcome these limitations it is suggested to have less feature dimensions, more accuracy and cost-effective imaging modality like X-ray. This is required to avoid bone fractures and to improve BMD with precision which further helps in the diagnosis of osteoporosis

Vocal fold vibratory and acoustic features in fatigued Karaoke singers

Session 3aMU - Musical Acoustics and Speech Communication: Singing Voice in Asian CulturesKaraoke is a popular singing entertainment particularly in Asia and is gaining more popularity in the rest of world. In Karaoke, an amateur singer sings with the background music and video (usually guided by the lyric captions on the video screen) played by Karaoke machine, using a microphone and an amplification system. As the Karaoke singers usually have no formal training, they may be more vulnerable to vocal fatigue as they may overuse and/or misuse their voices in the intensive and extensive singing activities. It is unclear whether vocal fatigue is accompanied by any vibration pattern or physiological changes of vocal folds. In this study, 20 participants aged from 18 to 23 years with normal voice were recruited to participate in an prolonged singing task, which induced vocal fatigue. High speed laryngscopic imaging and acoustic signals were recorded before and after the singing task. Images of /i/ phonation were quantitatively analyzed using the High Speed Video Processing (HSVP) program (Yiu, et al. 2010). It was found that the glottis became relatively narrower following fatigue, while the acoustic signals were not sensitive to measure change following fatigue. © 2012 Acoustical Society of Americapublished_or_final_versio