Use of Laser Systems in Orthodontics

Laser systems have been used in the practice of dentistry for >35 years. Laser systems have so many advantages, such as increase patient cooperation, reduce the duration of treatment time, and help the orthodontists to enhance the design of a patient’s smile to improve treatment efficacy, and the success of orthodontic treatments can also be improved by diminishing the orthodontic pain and the discomfort of the patients. Laser systems also have some disadvantages, such as cost, large space requirements for some types, and high-risk potential for physician and patient if not used at the appropriate wavelength and power density, that is why before incorporating lasers into clinical practice, the physician must fully understand the basic science, safety protocol, and risks associated with them. Lasers have many applications in orthodontics, including accelerating tooth movement, bonding and debonding processes, pain reduction, bone regeneration, etching procedures, increase mini-implant stability, soft tissue procedures (gingivectomy, frenectomy, operculectomy, papilla flattening, uncovering temporary anchorage devices, ablation of aphthous ulcerations, and exposure of impacted teeth), fiberotomy, scanning systems, and welding procedures. In reviewing the literature on the use of laser in orthodontics, many studies have been conducted. The purpose of the present study was to give information about the use of laser in the field of orthodontics, the effects of laser during the postoperative period, and its advantages and disadvantages and to provide general information about the requirements to be considered during the use of laser

Two dimensional generalized edge detector

Bu çalışmada, daha önce Gökmen ve Jain (1997) tarafından geliştirilen -uzayında görüntü  gösterimi ve ayrıt saptayıcı  iki boyutlu uzaya genişletilmektedir. Bu genişletme özellikle iki açıdan önemlidir. Birinci olarak, görüntülerin -uzayındaki davranışları en iyi, iki boyutlu düzleştirme ve ayrıt saptama süzgeçleri ile modellenebilir. İkincisi, genelleştirilmiş ayrıt saptayıcı (GAS) ile bilinen başarılı birçok ayrıt saptayıcısını üretebildiğinden, iki boyutlu GAS ile bu süzgeçlerin iki boyutlu biçimleri oluşturulabilir. Düzleştirme problemi, zar ve levha modellerinin doğrusal bileşiminden oluşan iki boyutlu karma enerji fonksiyonelinin en aza indirgenmesi olarak tanımlanmıştır. Gökmen ve Jain (1997) karma fonksiyoneli en aza indirgeyen denklemi, ayrıştırılabilir olduğu varsayımı altında tek boyutlu kısmi diferansiyel denklem olarak çözmüşlerdir. Ancak mevcut ayrıştırılabilir çözüm iki boyutlu özgün denklemi sağlamamaktadır. Bu çalışmada, karma fonksiyoneli en aza indirgeyen denklem takımı iki boyutlu uzaydaki çözümü sunulmaktadır. Türetilen süzgeçler önceki süzgeçlerle birinci ve ikinci tür hata karakteristiklerine göre karşılaştırıldığında gürültüye daha az duyar olduğu gözlenmiştir. Gerçek ve yapay görüntüler üzerinde yapılan deneysel sonuçlarla ayrıt saptayıcının performansı ve -uzayındaki davranışı sunulmuştur. Ayrıt saptayıcılar ile çalışırken ayarlanması gereken çok sayıda parametre bulunmaktadır. Verilen bir imge için en iyi parametre kümesini bulmanın genel geçer bir yöntemi bulunmamaktadır. Gerçektende, bir imge için en iyilenen bir ayrıt saptayıcının parametreleri başka bir imge için en iyi olmayacaktır. Bu çalışmada, en iyi GAS parametreleri, verilen bir imge için hesaplanan, alıcı işletim eğrisi üzerinden belirlenmiştir. Burada amaç GAS'ın başarımının sınırlarını göstermektir. Anahtar Kelimeler: Ayrıt saptama, düzenlileştirme kuramı, ölçek-uzayı gösterilimi, yüzey kurma.The aim of edge detection is to provide a meaningful description of object boundaries in a scene from intensity surface. These boundaries are due to discontinuities manifesting themselves as sharp variations in image intensities. There are different sources for sharp changes in images which are created by structure (e.g. texture, occlusion) or illumination (e.g. shadows, highlights). Extracting edges from a still image is certainly the most significant stage of any computer vision algorithm requiring high accuracy of location in the presence of noise. In many contour-based vision algorithms, such as shape-based query, curved-based stereo vision, and edge-based target recognition, their performance is highly dependent on the quality of the detected edges. Therefore, edge detection is an important area of research in computer vision. Despite considerable work and progress made on this subject, edge detection is still a challenging research problem due to the lack of a robust and efficient general purpose algorithm. Most of the efforts in edge detection have been devoted to the development of an optimum edge detector which can resolve the tradeoff between good localization and detection performance. Furthermore, extracting edges at different scales and combining these edges have attracted a substantial amount of interest. In the course of developing optimum edge detectors that can resolve the tradeoff between localization and detection performances, several different approaches have resulted in either a Gaussian filter or a filter whose shape is very similar to a Gaussian. Furthermore, these filters are very suitable for obtaining scale space edge detection since the scale of the filter can be easily controlled by means of a single parameter. For instance, in classical scale-space the kernel is a Gaussian and the scale-space representation is obtained either by convolving the image by a Gaussian with increasing standard deviation or equivalently by solving the linear heat equation in time. This representation is causal, since the isotropic heat equation satisfies a maximum principle. However, the Gaussian scale-space suffers from serious drawbacks such as over-smoothing and location uncertainty along edges at large scales due to interactions between nearby edges and displacements. Although these filters are used widely, it is very difficult to claim that they can provide the desired output for any specific problem. For instance, there are some cases where the improved localization performance is the primary requirement. In these cases, a sub-optimum conditions filter which promotes the localization performance becomes more appropriate. It has been shown that the first order R-filter can deliver improved results on checkerboard and bar images as well as some real images for moderate values of signal-to-noise ratio (SNR). In many vision applications, there is a great demand for a general-purpose edge detector which can produce edge maps with very different characteristics in nature, so that one of these edge maps may meet the requirements of the problem under consideration. Detecting edges in images is one of the most challenging issues in computer vision and image processing due to lack of a robust detector. Gökmen (1997) obtained an edge detector called Generalized Edge Detector (GED), capable of producing most of the existing edge detectors. The original problem was formulated on two-dimensional Hybrid model comprised of the linear combination of membrane and thin-plate functionals. Smoothing problem was then reduced to the solution of two-dimensional partial differential equation (PDE). The filters were obtained for one dimensional case assuming a separable solution. This study extends edge detection of images in lt-space to two-dimensional space. Two-dimensional extension of the representation is important since the properties of images in the space are best modeled by two dimensional smoothing and edge detector filters. Also since GED filters encompass most of the well-known edge detectors, two-dimensional version of these filters could be obtained. The derived filters are more robust to noise when compared to the previous one dimensional scheme in the sense of missing and false alarm characteristics. There are several parameters to tune when dealing with edge detectors. Usually there is no easy way to find the optimal edge detector parameters for an image. In fact, one set of optimal parameters may not be optimal for another image. In this study, we find optimal GED parameters using receiver operator characteristics for an image when its ideal edges are available using exhaustive search to see how best it achieves. Keywords: Edge detection, regularization theory, scale-space representation, surface reconstruction

Aktif görünüm modeline dayalı gürbüz yüz hizalama

In building a face recognition system for real-life scenarios, one usually faces the problem that is the selection of a feature-space and preprocessing methods such as alignment under varying illumination conditions and poses. In this study, we developed a robust face alignment approach based on Active Appearance Model (AAM) by inserting an illumination normalization module into the standard AAM searching procedure and inserting different poses of the same identity into the training set. The modified AAM search can now handle both illumination and pose variations in the same epoch, hence it provides better convergence in both point-to-point and point-to-curve senses. We also investigate how face recognition performance is affected by the selection of feature space as well as the proposed alignment method. The experimental results show that the combined pose alignment and illumination normalization methods increase the recognition rates considerably for all feature spaces. In this paper, we focus on the problems induced by varying illumination and poses. Our primary aim is to eliminate the negative effect of illumination and pose on the face recognition system performance through illumination and pose-invariant face alignment based on Active Appearance Model. Pose normalization is required before recognition in order to reach acceptable recognition rates. We developed AAM based pose normalization method which uses only one AAM. There are two important contributions over the previous studies. By using the proposed method: One can synthetically generate appearances for different poses when only frontal face image is available. One can generate frontal appearance of the face when there is only non-frontal face image is available. The same variation in pose imposes similar effect on the face appearance for all individuals. Deformation mostly occurs on the shape whereas the texture is almost constant. Since the number of landmarks in AAM is constant, the wireframe triangles are translated or scaled as pose changes. So as we change pose, only wireframe triangles undergo affine transformation but the gray level distribution within these triangles remains the same. One can easily generate frontal face appearance if AAM is correctly fitted to any given non-frontal face of the same individual provided that there is no self-occlusion on face. Self-occlusion usually is not a problem for angles less than ±45. For 2D pose generation, we first compute how each landmark point translates and scales with respect to the corresponding frontal counterpart landmark point for 8 different poses, and obtain a ratio vector for each pose. We use the ratio vector to create the same pose variation over the shape of another individual. Appearances are also obtained through AAM using synthetically generated landmarks. It is important to note that the generated faces contain no information about the individual used in building the ratio matrix. An AAM model trained by using only frontal faces can only fit into frontal faces well and fail to fit into non-frontal faces. Our purpose here is to enrich the training database by inserting synthetically generated faces at different poses so that AAM model trained by frontal faces can now converge to images at any pose. In this paper we developed AAM based face alignment method which handles illumination and pose variations. The classical AAM fails to model the appearances of the same identity under different illuminations and poses. We solved this problem by inserting histogram fitting based normalization into the searching mechanism and inserting different poses of the same identity into the training set. From the experimental results, we showed that the proposed face restoration scheme for AAM provides higher accuracy for face alignment in point-to-point error sense. Recognition results based on PCA and LDA feature spaces showed that the proposed illumination and pose normalization outperforms standard AAM. Keywords: Face alignment, active appearance models, illumination invariant face recognition.Yüz görünümündeki şekil ve doku değişimine bağlı farklılıklar yüz tanıma problemini oldukça zor hale getirmektedir. Bireyler arası yüz görünüm farklılıklarının fazla olmasına karşın, her bireyin kendi yüz görünümünü farklı hale getirecek değişimlerde mevcuttur. Özellikle aydınlatma ve poz değişimleri yüz tanıma sistemlerinin başarımını etkileyen zorlukların başında gelmektedir. Bu çalışmada otomatik yüz hizalama için aydınlatma ve poz değişimlerine karşı gürbüz yeni bir yöntem tanıtılmıştır. Klasik aktif görünüm modeli (AGM) yapısına yüz için özelleştirilmiş aydınlatma normalizasyonu eklenerek AGM’nin farklı aydınlatma koşullarındaki arama ve yakınsama performansını arttıran yeni bir yöntem önerilmiştir. AGM ile yüz bölütlemede, özgün yüz aydınlatma normalizasyonunu AGM bükme (warping) işleminden hemen sonra ve her çevirimde uygulayarak aydınlatma değişimlerine karşı gürbüz bir model oluşturulmuştur. Yöntem giriş olarak verilen farklı aydınlatılmış ve farklı bir poza sahip yüz görüntüsünü hem iyileştirmeye hem de hizalamaya çalışmaktadır. Ayrıca tam karşıdan çekilmiş tek bir yüz görüntüsünden, o kişinin farklı pozlara sahip görüntülerini sentezleyen bir yöntem tanıtılmış ve sentetik olarak sentezlenen poz verileri ile AGM şekil uzayı güçlendirilerek poz değişimlerine karşı gürbüz bir yöntem önerilmiştir. Önerilen yöntemde, model eğitimi için aynı bireyin farklı aydınlatma ve poza sahip görüntülerine ihtiyaç duyulmamaktadır. Önerilen yöntemde aydınlatma değişimlerine karşı bağışık bir yapı oluşturulması için karmaşık aydınlatma modelleri gerekmemektedir. Deneysel çalışmalardan da görüleceği gibi önerilen yöntem, farklı aydınlatma ve pozlarda bile klasik AGM’ye göre oldukça iyi sonuçlar vermiştir. Anahtar Kelimeler: Yüz hizalama, aktif görünüm modelleri, aydınlatmadan bağımsız yüz tanıma

Comparison of Soft Tissue Profile between Subgroups of Skeletal Class III Malocclusion

Aim:The aim of this study is to compare the soft tissue profiles of patients with skeletal Class III malocclusions originated from; maxillary retrusion, mandibular protrusion and the combination of maxillary retrusion and mandibular protrusion.Material and Method:Lateral cephalomet-ric radiographs of 66 subjects were divided into three groups according to the Nperp-A and Nperp-Pg variables; Group 1-maxil-lary retrusion (n:23; mean age:13.44 years), Group 2-mandibular protrusion (n:22; mean age:13.31 years), and Group 3-combination of maxillary retrusion and mandibular protrusion (n:21; mean age:13.04 years). Besides the descriptive parameters of Class III subgroups, 13 soft tissue measurements (Gl-Sn, Sn-Me, ULL, St-Me, Sn-LLV, LLV-Me, interlabial distance, upper lip, lower lip, Chin, Gl-Sn/Sn-Me, Sn-St/St-Me and Sn-LLV/LLV-Me) were achieved for evaluating the possible differences between Class III subgroups. The differences between all Class III groups were evaluated by Analysis of Variance (ANO-VA) and Duncan test.Results:Chin measurement (distance between soft tissue pogonion to vertical reference plane) showed the highest value in Group 1 (5.14 ± 2,93) compared with Groups 2 (2.94 ± 2,15) and 3 (3.05 ± 1,98) (p<.01). Although the differences in Sn-Me and LLV-Me are insignificant among groups, these parameters representing the lower anterior soft tissue heights have the highest values in group 3. The rest of the parameters did not show statistical significance between the groups.Conclusion:Decreased lower lip and significantly increased soft tissue chin measurement were found in maxillary ret-rusion group. Both cephalometric and clinical examinations of soft tissues are needed for a proper diagnosis and treatment of orthognathic surgery cases

Thermoluminescence study of Mn doped lithium tetraborate powder and pellet samples synthesized by solution combustion synthesis

In this paper, the thermoluminescence (TL) dosimetric characteristics under beta-ray, x-ray and gamma-ray excitations of powder and pellet Mn-doped lithium tetraborates (LTB) which were produced by solution combustion synthesis technique were investigated, and the results were compared with that of TLD-100 chips. The chemical composition and morphologies of the obtained LTB and Mn-doped LTB (LTB:Mn) were confirmed by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) and scanning electron microscopy (SEM) with EDX. LTB:Mn was studied using luminescence spectroscopy. In addition, the effects of sintering and annealing temperatures and times on the thermoluminescence (TL) properties of LTB:Mn were investigated. The glow curves of powder samples as well as pellet samples exposed to different beta doses exhibited a low temperature peak at about 100 °C followed by an intense principal high temperature peak at about 260 °C. The kinetic parameters (E, b, s) associated with the prominent glow peaks were estimated using Tm-Tstop, initial rise (IR) and computerized glow curve deconvolution (CGCD) methods. The TL response of integral TL output increased linearly with increasing the dose in the range of 0.1-10 Gy and was followed by a superlinearity up to 100 Gy both for powder and pellet samples using beta-rays. Powder and pellet LTB:Mn were irradiated to a known dose by a linear accelerator with 6 and 18 MV photon beams, 6-15 MeV electron beams and a traceable 137Cs beam to investigate energy response. Further, TL sensitivity, fading properties and recycling effects related with beta exposure of LTB:Mn phosphor were evaluated and its relative energy response was also compared with that of TLD-100 chips. The comparison of the results showed that the obtained phosphors have good TL dose response with adequate sensitivity and linearity for the measurement of medical doses

Effects of Fixed and Removable Functional Appliances on Skeletal and Dentoalveolar Structures

Aim:To compare the skeletal and dentoalveolar changes after Herbst and Twin-block treatment in Class II division 1 patients.Subjects and Methods:Cephalomet-ric radiographs of 20 patients treated with Herbst and Twin-block appliance and 10 untreated subjects are used. Totally 29 maxillary, mandibular, maxillomandibu-lar and dentoalveolar measurements were achieved. Paired sample t-test was used to determine intra-group differences and one way analysis was used to determine inter-group differences.Results:After Herbst appliance therapy, an increase in mandibular corpus length and mandibular incisor protrusion and decrease in ANB, overjet and overbite were observed. In Twin-block group, significant increases were observed in all mandibular measurements except nasion perpendicular to pogonion. A point moved anteriorly and effective middle face length increased. Increases were observed in effective mandibular length and in all measurements that show mandibular sagittal (Go-Gn) and vertical (Co-Go, S-Go) dimension. Only maxillary nasal plane to upper first molar length that shows maxillary molar eruption increased in dental measurements. Comparison of groups showed that both appliances decreased ANB angle and overjet. In Herbst group, significant differences were observed in effective middle face dimension and distance of Nasion perpendicular to A point, compared with the Control group. No significant difference was observed in other mandibular and dentoalveoler measurements between the groups.Conclusions:Twin-block appliance showed more skeletal changes and the Herbst appliance showed skeletal and dental changes in our study. The appliances exhibited similar effects compared with the Control group

The Position of Maxilla in Class III Patients

The purpose of the study was to identify the maxillary growth trend of the skeletal Class III individuals with and without openbite, and to define if the growth of the maxilla is effected by the position of the mandible. The patients included in the study were divided into three groups. The first group consisted of individuals (female: 8, male: 6, total: 14; mean age 14.3 years) with skeletal Class III + open-bite, the second group consisted of individuals (female: 7, male: 7, total: 14; mean age 13.8 years) with skeletal Class III without openbite and the third group, which acted as the control group consisted of individuals (female: 12, male: 5, total: 17; mean age 13.1 years) with skeletal Class I relationship. The measurements were done on pre-treatment/pre-control lateral cephalometric radiographs. In the study, the descriptive measurements (SNA, SNB, ANB, overjet, overbite, SN/Go-Gn, ANS-Me), measurements that define the size and position of the maxilla (A-VR, Co-A, ANS-PNS, Nperp-A) and the mandible (B-VR, Pg-VR, S-Go, Co-Go, Co-Gn, Go-Gn, Nperp-Pg) were evaluated. The differences between the groups were determined by Analysis of Variance and Duncan's tests. There were statistically significant differences between the two skeletal Class III groups in B-VR (p<0.05), ANS-Me, overjet and overbite (p<0.01). The parameters related with the growth of the maxilla were similar in both groups. The skeletal and positional structure of the maxilla in Class III individuals happen to be hardly influenced by the restriction of the mandibular incisors and negative overjet

Effects of Functional Anterior Shifting On Skeletal and Airway Structures

To compare the maxillary and mandibular skeletal structures and airway dimensions between anterior functional shifting and Class I control patients. This study was composed of 48 patients. The first group was consisted of 24 patients (male: 11, female: 13). Mean ANB value was 0.31 ± 3.49 and mean age is 13.52 ± 2.95. The second group was a skeletal Class I group, and consisted of 24 patients (male: 7, female: 17) and served as the control group. Mean ANB was 2.47 ± 2.27 and mean age was 13.99 ± 1.79. Eighteen cephalometric measurements were used to evaluate skeletal differences, and 14 measurements were used for airway dimensions. Two groups were compared with independent t test. Position and size of the mandible were not affected with anterior functional shifting. S-Go distance was smaller in anterior functional shifting patients (p<0.05). Hard palate - soft palate angle was statistically lower (p< 0.01) and soft palate length (pns-spt) was higher (p<0.01) in anterior functional shifting group. Inferior airway measurement (sbti-phwl) represented higher values in functional anterior shifting group (p< 0.05). There were statistically significant differences in Pns-ppw1 (p< 0.05), spl/sps (p< 0.01) and spl/Ips (p< 0.01) measurements. Patients with anterior functional shifting showed wider airway than Class I control group. Postnatal maxillary development deficiency may be observed in functional anterior shifting cases

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030