Cast Models Research Articles

Forsus Nitinol Flat Spring and Jasper Jumper corrections of Class II division 1 malocclusions.

To compare the effects of Forsus Nitinol Flat Spring (FNFS) and Jasper Jumper (JJ) in the correction of Class II division I malocclusions. Our research was conducted on 48 adolescents, who had a normal or horizontal growth pattern and retrognathic mandible. The patients were divided into three equal groups randomly. First group was treated with FNFS, and the second group was treated with JJ appliances, whereas the third group was the control group. Lateral cephalograms and study models were obtained after the leveling phase and at time of the removal of the appliances. Cephalometric analysis revealed that both the appliances stimulated mandibular growth, increased the anterior face height because of the lower face, and elongated the posterior face height because of the growth of temporomandibular joint. Maxillary central incisors were extruded, retruded, and distally tipped. Contrarily, intrusion, protrusion, and labial tipping were observed in the mandibular central incisors. Distal movement and intrusion of the maxillary first molars and mesial movement and extrusion of the mandibular first molars were the other dental alterations. Overjet and overbite were decreased, and a Class I molar relationship and improvement in the profile were attained in both treatment groups. Cast model analysis showed expansion in the maxillary and mandibular dental arches. Both the appliances were effective in the treatment of Class II malocclusion and revealed nearly same alterations in the skeletal, dental, and soft tissue parameters.

The practical clinical value of three-dimensional models of complex congenitally malformed hearts

Detailed 3-dimensional anatomic information is essential when planning strategies of surgical treatment for patients with complex congenitally malformed hearts. Current imaging techniques, however, do not always provide all the necessary anatomic information in a user-friendly fashion. We sought to assess the practical clinical value of realistic 3-dimensional models of complex congenitally malformed hearts. In 11 patients, aged from 0.8 to 27 years, all with complex congenitally malformed hearts, an unequivocal decision regarding the optimum surgical strategy had not been reached when using standard diagnostic tools. Therefore, we constructed 3-dimensional virtual computer and printed cast models of the heart on the basis of high-resolution whole-heart or cine magnetic resonance imaging or computed tomography. Anatomic descriptions were compared with intraoperative findings when surgery was performed. Independently of age-related factors, images acquired in all patients using magnetic resonance imaging and computed tomography proved to be of sufficient quality for producing the models without major differences in the postprocessing and revealing the anatomy in an unequivocal 3-dimensional context. Examination of the models provided invaluable additional information that supported the surgical decision-making. The anatomy as shown in the models was confirmed during surgery. Biventricular corrective surgery was achieved in 5 patients, palliative surgery was achieved in 3 patients, and lack of suitable surgical options was confirmed in the remaining 3 patients. Realistic 3-dimensional modeling of the heart provides a new means for the assessment of complex intracardiac anatomy. We expect this method to change current diagnostic approaches and facilitate preoperative planning.

Surgically Assisted Palatine Expansion in Adult Patients: Evaluation of a Conservative Technique

This study was conducted to assess a conservative technique for surgically assisted palatine expansion (SAPE) done under local anesthesia and conscious sedation in adults. Dental inclination, uniformity of expansion, and satisfaction of orthodontist were evaluated. Twenty-seven consecutive patients, ranging in age from 25 to 42 years, underwent SAPE under local anesthesia. The surgical procedure involved osteotomy of the lateral wall of the maxilla, from the maxillary tuberosity to the nasal cavity, with the nasal septum and the ptyerigoid plates left intact. Cast models were obtained before surgery and 1 year after surgery. Cuspid inclinations were assessed, with intercanine distance in 2 points, the incisal and cervical borders, measured before and after surgery. Molar inclination was obtained by measuring intermolar distance at the cervical margin and occlusal table. The results were statistically analyzed by analysis of variance. A questionnaire with 4 questions was addressed to the orthodontists to evaluate the level of satisfaction with the procedure. Cuspid and molar inclination occurred, but there was no statistically significant difference (P < .05) in dental inclination before and after surgery. The expansion was greater at the molar level than at the canine level, but this difference also was not statistically significant (P > .05). According to the questionnaire, 100% of the procedures allowed the expansion, 100% of the orthodontists were satisfied, and 68.75% observed dental inclination, but this inclination was not excessive in 100% of the cases. The proposed technique is a safe, predictable, and reliable method for SAPE in adult patients. Although ptyerigoid plate and nasal septum fractures were not performed, the maxillary bone exhibited uniform expansion. Dental inclination was not significant, either clinically or during cast model analysis. Orthodontists could achieve treatment objectives with this surgical procedure.

Dimensões dos arcos dentários na má oclusão Classe II, divisão 1, com deficiência mandibular

OBJETIVO: identificar alterações dimensionais nos arcos dentários superior e inferior na má oclusão Classe II, divisão 1, com deficiência mandibular (Padrão esquelético II). MÉTODOS: 48 pacientes com má oclusão Classe II, igualmente divididos quanto ao gênero, foram comparados com 51 indivíduos com oclusão normal, sendo 22 do gênero masculino e 29 do gênero feminino. Todos os 99 indivíduos estavam no estágio de dentadura permanente, com os segundos molares permanentes irrompidos ou em irrupção, com idade média de 12 anos e 5 meses (desvio-padrão de 1 ano e 3 meses), numa faixa etária oscilando entre 11 anos e 4 meses e 20 anos. CONCLUSÃO: os resultados permitem concluir que, na má oclusão Classe II, divisão 1 com deficiência mandibular, o arco dentário superior encontra-se alterado, mostrando-se atrésico e mais longo, enquanto o arco dentário inferior é pouco influenciado pela discrepância sagital de Classe II.

Desenvolvimento e comparação de um método de construção de arcos ortodônticos individualizados com um método tradicional de escolha de arcos ortodônticos pré-fabricados

INTRODUÇÃO: a existência de pacientes com arcos dentários e anatomias diferentes dos diagramas de arcos ortodônticos preestabelecidos justifica este trabalho. OBJETIVO: foi proposto mostrar um método de construção de arcos ortodônticos que respeitasse a anatomia individual de cada paciente e que fosse construído sem a necessidade de diagramas impressos pré-desenhados. MÉTODOS: em vinte modelos inferiores de gesso, foram colados, no centro da coroa clínica dos seus dentes, braquetes e tubos. Com o auxílio de um paquímetro digital associado a um aparelho que posicionou os modelos com o plano oclusal paralelo ao solo, foi possível medir a distância da ponta de cúspide e meio da face incisal de cada dente até o fundo da canaleta do respectivo braquete e tubo colado. De posse dessas medidas, foram realizadas impressões das cúspides dentárias dos modelos em uma lâmina de cera 7 e, a partir dessas cúspides, pontuou-se a cera usando a distância obtida (entre a ponta de cúspide/meio da incisal dos dentes e a canaleta do braquete/entrada do tubo). Esses novos pontos serviram de referência para a construção dos arcos ortodônticos individualizados. RESULTADOS E CONCLUSÃO: esse método de construção foi denominado "arcograma", o qual foi comparado com um método pré-conformado de diagramação ("Tru-arch"), sendo considerado melhor que esse no tocante à adaptação à anatomia individual do arco.

Three-Dimensional Measurement of the Mandible After Mandibular Midline Distraction Using a Cemented and Screw-Fixated Tooth-Borne Appliance: A Clinical Study

The aim of this study was to analyze the 3-dimensional movement of the mandible segments after distraction of the mandibular midline by use of a cemented and screw-fixated tooth-borne appliance. Twenty patients with transverse deficiencies of the lower arch were included in a consecutive study. Before surgical intervention, a custom-made appliance was cemented to the teeth and also fixed with 2 screws between the teeth on each side. The distraction appliance was activated after 5 days at a rate of 0.6 mm/d. After a consolidation period of 6 weeks, the appliance was removed and an orthodontic retainer was applied. Radiographs and cast models were taken preoperatively and postoperatively, and direct linear measurements were performed at the same intervals. Mean expansion (+/- SD) of the osteotomy line measured on the radiographs for the superior, middle, and inferior part of the mandible was 5.1+/-2.4, 5.9+/-2.8, and 5.7+/-2.9 mm, respectively. The mean overall expansion was 5.6+/-2.6 mm. The width increase of the models between the canines, first premolars, second premolars, first molars, and second molars was 4.2+/-1.8, 5.0+/-2.0, 4.7+/-2.0, 4.3+/-1.7, and 3.6+/-1.3, respectively, at the tooth level and 3.4+/-2.0, 3.6+/-1.8, 3.3+/-1.4, 3.2+/-1.5, and 2.2+/-1.8, respectively, at the bone level. Expansion of the osteotomy line in the vertical dimension showed a uniform pattern. Lateral movements of the mandibular segments decreased from the symphysis to the gonial angles. The positional changes of the teeth and the bone segments were proportionate. Minimal dental movement was observed.

Simulation of Surface Mesh Deformation in Orthodontics by Mass-Spring Model

The mass-spring model has been used to describe elastically deformable models such as skin, textiles, and soft tissue in computer graphics. A mass-spring mesh is composed of a network of masses and springs, in which each edge is a spring. We apply the mass spring system to mesh deformation in 3D orthodontic simulation, the movement of which is evaluated using the numerical integration of the fundamental law of dynamics based on the 4th-order Runge-Kutta method. Computational quantity and accuracy is demonstrated on test and dental cast model examples. The experimental results show that it can simulate the deformation change in real time and display the results vividly.

Dental arch morphology of Mazahua and mestizo teenagers from central Mexico

Aim: The aim of this study was to determine the morphologic characteristics of the dental arches in the ethnic group “Mazahua” and mestizo teenagers from central Mexico. Methods: A sample of 80 Mazahua and 80 mestizo teenagers with normal occlusion, divided into two age groups, were evaluated. A digital caliper was used to measure in cast models the intercanine width, intermolar width, length and perimeter of the arch, occlusal intermaxillary curve (of Spee), overjet, and overbite. A comparative analysis with Student’s t-test was applied between gender and population groups. Results: Comparison of the dental arches between Mazahua and mestizo teenagers revealed that statistically significant differences existed with respect to most of the measurements. In most cases, they were greater in males; the Mazahua teenagers had intercanine and intermolar widths greater than mestizo teenagers. Conclusions: Each group has a characteristic dental arch form. The ethnic group Mazahua has squared arches, whereas the mestizo teenagers have oval arches, which give them their particular facial characteristics. These findings indicate that population-specific standards are necessary for clinical assessments.

Quantifying the amount of padding improves the comfort and function of a fibreglass below-elbow cast

Aim To determine the quantity of cotton underpadding needed for a comfortable, functional, below-elbow fibreglass cast. Methods In this randomised, prospective, crossover, clinical trial, 45 people with minimally displaced distal radial fractures were enrolled to randomly receive, 14 days after injury, a fibreglass below-elbow cast with either two or four layers of cotton underpadding. The characteristics of the recipients were recorded. After 2 weeks of immobilisation, participants completed a numerical survey evaluating parameters of comfort and underwent clinical and radiographic assessment. They then crossed over to receive the other fibreglass cast design, the process was repeated, and they indicated their cast preference, if any. Results Of 37 people who completed the study, 20 preferred the two-layer model, 13 the four-layer model and 4 had no preference. No significant trend for one design over the other was shown ( p = 0.1), nor any statistical association between preference and participant characteristics or the order in which cast models were received. Conclusions Participants did state a preference, but this was not related to recipient characteristics. Neither cast design was significantly the more comfortable; and both models were safe and functionally satisfactory.

Development and testing of particulate formulations for the nasal delivery of antibodies

Therapeutic antibodies offer a potential treatment for, or means of protection against, airborne infections. For this application, it may be desirable to deliver the antibody directly into the nasal cavity, one of its potential sites of action, since this would be more efficient and convenient than systemic administration. Formulations of a model antibody (human IgG) were developed using albumin, sodium chloride and disaccharides. A combination of these excipients allowed the efficient spray-drying (yield > 70%) of the antibody into a microparticulate (1–15 µm) dry powder that was rapidly soluble in aqueous media. The water content and crystallinity of the formulations were also measured, with both properties being affected by the substitution of some of the sodium chloride in the formulation, with lactose. The antibody was found to be stable following the formulation process, as determined by gel-electrophoresis, field-flow-fractionation and enzyme-linked immunosorbent assay. Incubation of an in vitro epithelial cell line in the presence of solutions of the formulations (at concentrations of up to 2500 µg/mL) was found not affect cell viability. The aerosolisation properties of the formulations were tested using Bespak's “Unidose-DP ™”, dry-powder nasal device. The powder aerosol was analysed by laser diffraction, high-speed video and dose deposition in Bespak's nasal cast model. For the latter experiment, a range of additional excipients were either dissolved in the spray-drying liquid feed (leucine), or blended with the spray-dried powder formulation (magnesium stearate, Aerosil ® and lactose). The major dose deposition site of the standard spray-dried formulation was the nasal vestibule (~ 55%). The addition of leucine and Aerosil ® resulted in a 10% increase in the deposition beyond the nasal vestibule, with ~ 45% of the delivered dose being deposited in the turbinates, olfactory region, and nasal-pharynx.

Prediction of Transverse Maxillary Dimension Using Orthodontic Models

The main objective of this study was to quantify the transverse maxillary dimensions using orthodontic cast models of individuals with natural normal occlusion. Sixty-eight pairs of orthodontic models were evaluated with the respective posteroanterior radiographies of white adults (38 women and 30 men; mean age, 17 years and 5 months). The models were placed in Class I molar occlusion, and on each pair, 4 points were marked on the alveolar buccal ridge (2 on the premolar region and 2 on the molar), determining the upper and lower transverse interpremolar and intermolar dimensions. The variables analyzed in the 3 measurements, obtained from the cephalometric radiographies and the cast models, showed no statistical differences. The upper intermolar distance was 57.20 +/- 2.60 mm; the lower intermolar, 55.16 +/- 2.40 mm; the upper interpremolar, 42.17 +/- 2.19 mm, and the lower interpremolar; 39.67 +/- 1.77 mm. On the posteroanterior cephalograms, the maxillary width was 65.97 +/- 3.42 mm and the mandibular width was 87.92 +/- 4.60 mm. There was intraresearcher and interresearcher correlation. There was no sexual dimorphism. The method proposed in this study can predict the transverse maxillary dimension, applying the formula ym = 8.62 + 0.88xm (ym = expected upper intermolar distance, xm = lower intermolar distance) for the molar region, and ypm = 4.87 + 0.94xpm (ypm = expected upper interpremolar distance, xpm = lower interpremolar distance) for the premolar region.

Development of a nasal cast model to test medicinal nasal devices

Bespak, a division of Consort Medical plc, and Queen's University Belfast have developed a viable and unique in-vitro testing capability for nasal drug delivery devices. The aim was to evaluate and optimize current and conceptual drug delivery devices by quantifying the deposition of drug in the various distinct regions of the nasal cavity. The development of this test apparatus employed computed tomography (CT) scan data of the human nasal cavity to construct an accurate representation of the human nasal airways. An investigation of suitable materials and manufacturing technologies was required, together with extensive analytical method development. It is possible for this technique to be further developed in an attempt to create a standardized apparatus based on nasal geometry that can be used to compare accurately deposition from drug delivery devices. This paper presents the issues encountered in the development of this test apparatus, including manufacturing and material limitations, investigation and choice of suitable materials, laboratory testing considerations, and the steps required to validate the analytical process.

통합적 접근이 필요한 지구과학 개념에 대한 예비 교사의 이해: 현상론적 초안과 국면 분석을 통한 식 현상에 대한 정신모형 탐색

본 연구에서는 통합교과적 접근이 필요한 지구과학 개념에 대한 예비 교사들의 이해를 알아보기 위하여 식 현상에 대한 예비 교사들의 정신 모형을 탐색하였다. 본 연구에는 30명의 중등 예비 지구과학 교사와 36명의 초등 예비교사들이 참여하였다. 정신 모형의 분석을 위해서 서로 다른 맥락의 질문지에 대한 예비 교사들의 응답 및 질문지를 토대로 한 심층 면담 과정에서 나타난 현상론적 초안과 전략적 국면을 분석하였다. 연구 결과, 식 현상에 대해 예비 교사들은 4개의 서로 다른 수준의 정신 모형을 가진 것으로 분석되었다: (1) 차폐 모형, (2) 공전궤도면 모형, (3) 혼성모형, 그리고 (4) 그림자 모형, 차폐 모형은 결함이 있는 모형이며, 공전궤도면 모형은 불완전한 모형, 그림자 모형은 과학적으로 옳은 모형이다. 혼성 모형은 두 개 이상의 정신 모형을 동시에 사용한다. 중등 예비 교사의 경우는 공전궤도면 모형이 40%로 가장 우세한 반면, 초등 예비 교사의 경우는 차폐 모형이 67%로 가장 많았다. 국면의 수준이 정신모형의 수준을 결정하며, 국면의 수준은 현상론적 초안에 의해 결정되는 것으로 분석되었다. 이 연구를 통해 정신 모형의 상황 의존성을 확인하였으며, 식 현상에 대한 낮은 수준의 정신 모형들이 개념적 모형으로 바뀌기 위해서는 광학과 기하학이 통합된 새로운 접근이 필요함을 알 수 있었다. 또한 정신 모형의 규명을 통한 예비 과학 교사의 주제 특정적 교과교육학 지식의 향상 가능성을 시사하였다. This study explored pre-service teachers' mental models about eclipse phenomena to investigate their understandings on the earth science concept needed f3r an integrated approach. We conducted in-depth interviews with two different contexts on 30 secondary and 36 primary pre-service teachers participants, and analyzed phenomenological primitives (p-prims) and facets of causal explanations about eclipses. Based on this study, we identified four different levels of mental models about eclipses. Four mental models were categorized as (1) Screening model, (2) Orbital plane model, (3) Hybrid model, and (4) Shadow cast model. Screening model is a flawed mental model, orbital plane model is an incomplete correct mental model, and shadow cast model is a scientifically correct mental model. Hybrid model, composite of two or more mental models, use multiple mental models simultaneously. Orbital plane model was the most widespread mental model in secondary pre-service teachers group, whereas screening model was used frequently in primary group. It was found that the level of mental model could be determined by the level of facet and p-prims. We confirmed context sensitivity of the mental models and perceived the necessity of integrated approaches to promote progression of mental models. Implications of our findings for enhancing pre-service science teachers' topic-specific pedagogical content knowledge (PCK) associated with eclipse phenomena are also discussed here.

R458 – Drug Delivery to the Sinuses- Basics and Aerosol Dynamics

Problem Drug delivery to the sinuses via aerosols appears to be a very difficult task, since the paranasal cavities are virtually non-vented cavities. However, there is a scientifically traceable approach to transport aerosol to the sinuses via pressure differences using so-called “vibrating” or “sonic” aerosols which suggests that pressure fluctuations increase aerosol diffusion and ventilate dead spaces by flow induction. Methods The influence of droplet size, vibration frequency and flow rate on drug delivery to the nasal and paranasal cavities was studied in a human nasal cast model (NC). One ml of a Levofloxacin solution (100 mg/ml) was aerosolized into the NC by a VibrENT prototype nebulizer generating a slow, high density aerosol (MMD = 3.7μm) via a perforated vibrating membrane in connection with an adjustable pulsation source. Results Total paranasal cavity deposition was highest (-20 % of label claim) configured with ostia of 1 and 3 mm in diameter and sinus volumes of 7, 12 and 23 ml when VibrENT was operated at flow rates below 3 1/min and a pulsation frequency of 36 Hz. Delivery efficiency decreased at higher frequencies, higher flow rates and with larger aerosol droplets. Omission of pulsation resulted in no paranasal deposition and a drop in nasal cavity deposition from more than 50% to about 6%. Drug deposition to the sinuses is also significantly (p&lt;0.01) affected by the ostium diameter and sinus volume, being lowest (∼0.2 %) at a large ostium diameter (6 mm) and a low sinus volume (7 ml). Conclusion It is possible to deliver aerosol to the sinuses but physical boundary conditions like pulsation frequency, aerosol size and flow rate have to be considered for an efficient transport as well as sinus anatomy. PARI VibrENT addresses these requirements. Significance Efficient drug transport to the sinuses enables novel therapeutic approaches.

Bayes Reconstruction of Missing Teeth

We propose a method for restoring the surface of tooth crowns in a 3D model of a human denture, so that the pose and anatomical features of the tooth will work well for chewing. This is achieved by including information about the position and anatomy of the other teeth in the mouth. Our system contains two major parts: A statistical model of a selection of tooth shapes and a reconstruction of missing data. We use a training set consisting of 3D scans of dental cast models obtained with a laser scanner, and we have build a model of the shape variability of the teeth, their neighbors, and their antagonists, using the eigenstructure of the covariance matrix, also known as Principle Component Analysis (PCA). PCA is equivalent to fitting a multivariate Gaussian distribution to the data and the principle directions constitute a linear model for stochastic data and is used both for a data reduction or equivalently noise elimination and for data analysis. However for small sets of high dimensional data, the log-likelihood estimator for the covariance matrix is often far from convergence, and therefore reliable models must be obtained by use of prior information. We propose a natural and intrinsic regularization of the log-likelihood estimate based on differential geometrical properties of teeth surfaces, and we show general conditions under which this may be considered a Bayes prior. Finally we use Bayes method to propose the reconstruction of missing data, for e.g. finding the most probable shape of a missing tooth based on the best match with our shape model on the known data, and we superior improved reconstructions of our full system.

A new system for scanning, measuring and analyzing dental casts based on a 3D holographic sensor

To evaluate the reliability of a new technique for measuring 3D-scanned orthodontic cast models with cross-section planes using teledent, a new software, developed at Technion - for the purpose of this research. Thirty orthodontic plaster models were divided into three equal groups according to severity of teeth crowding. Measurements of mesio-distal tooth width and the arch length were performed manually on the casts using a conventional caliper. Thereafter, the models were scanned and processed into the software using a 3-D measuring scanner with a holographic sensor 'ConoProbe' (by Optimet, Jerusalem, Israel). teledent used two types of digital measurements; linear and cross-section planes to perform a space analysis on the scanned teeth. Significance was determined by the paired Wilcoxon rank sum test. Results show that 3D measurements of tooth width and arch length obtained by cross-section planes were generally similar to manual caliper measurements, while linear measurements were statistically smaller. When comparing space analysis, both digital measurements were statistically smaller than the caliper (p < 0.05). The difference in space analysis between the caliper and the cross-section plane measurements was very small (0.38-0.74 mm) and can be considered clinically acceptable. However, a difference of 1.19-3 mm between the linear measurements and the caliper might have clinical implications especially in severely crowded dentition. This study suggests that measurements performed by cross-section planes are as accurate as the manual caliper and can be employed clinically while the accuracy of linear measurements is sometimes questionable.

3D morphological assessment of occlusal treatment by measuring dental casts with a micro‐focus X‐ray CT

The analysis of occlusal relationship is important for the success of dental treatment. Three-dimensional (3D) computer models of upper and lower dental casts can play a significant role. In this study, we proposed and applied a new method in actual clinical assessment to measure dental casts with occlusal relationship by using a micro-focus X-ray CT system. We examined the modelling accuracy by comparing multiple 3D images taken by shifting the dental cast position. Modelling accuracy was confirmed as 0.03 mm. One occlusal treatment in clinical practice was selected as a case example. The dental casts and bite impression, taken before treatment, were scanned and the occlusal contacts and distance distribution between the upper and lower casts were visualized by a coloured map and overlaid on the computer models. Distances between the upper and lower casts of selected points were compared before and after the treatment. Initially, the subject had early contact on the anterior teeth, where distance was measured as 0.04 mm, and only one area measured less than 0.15 mm. After treatment, five areas measured less than 0.15 mm. Also, by comparing the dental cast models taken before and after occlusal adjustment of the tooth, the position and amount of adjustment were visualized. We successfully demonstrated the quantitative clinical assessment of occlusal treatment.

Form and size of the dental arches in a school population of Amazonian’s aborigines.

Objective: The purpose of this study was to determine dental archs’ shape, and to describe differences in transversal dimensions and archs’ depths in mixed dentition, in order to know occlusal harmony arrangement in a native student population from Leticia, Amazonas, Colombia. Methods and materials: A cross-sectional study with 64 students (32 boys and 32 girls) distributed in two groups: 31 students with early mixed dentitions and 33 students with belated mixed dentitions between 6 and 12 years old was carried out. Studied variables were measured from plaster cast study models. Results: Oval upper arch was found in 86% of students while 14% had squared upper arch. Proportions for lower arch shape were 75% oval and 25% squared, respectively. Most of the transversal dimensions had differences in both groups. Inferior intercanine distances were constant. Depth, width and length measurements are evidence of harmonic dental arch development for Amazonian children. Discussion: This ethnic group had higher oval arch shape prevalence, followed by squared arch shape There were differences for all arch depth measurements, mainly in anterior sector due to the susceptibility to environmental factors in mixed dentition period. Conclusions: Occlusal harmony in this population is a result of arch shape, as well as transversal and depth changes physiologically normal.

Characterisation of as cast model Mn–Si–Cr–Ni steels for reactor pressure vessel applications

Initial results are reported from a study aimed to investigate the role and influence of the elements Cr, Ni, Mn and Si on the radiation stability of reactor pressure vessel steels. Twelve as cast model ferritic steels with basic composition typical of those used in Russian WWER-1000 and Western PWR reactor pressure vessel materials were subjected to Charpy impact, magnetic Barkhausen noise (MBN), Vickers hardness tests and SEM examination. Higher Cr content in model steels was found generally to give increased RMS values independent of Mn and Si contents. The ductile–brittle transition temperatures (DBTT) and hardness values of the model steels were found to be independent of composition. Two steels, with low concentration of Ni and high concentration of Cr or vice versa , showed high transition temperatures (−16 and −42°C respectively). An additional heat treatment to improve the properties is being considered for these compositions. The correlation between DBTT and MBN results has potential for rapid determination of the effect of composition and irradiation on the steel properties. The next stage of the assessment will investigate the effect of irradiation of the model steels to accumulated neutron fluences of ∼1019 cm−2.

3D Multicamera Dental Cast Scanning System

A possibility of creating a high accuracy device that could automatically measure dental arches by scanning dental casts is presented. The original multicamera system using four firewire cameras and two laser modules is designed. System software uses acquired data for measurement of dental arches, to store dental cast models in 3D databases, to use model data for design of appliances. The 15 dental casts were scanned and measured to test the reliability of multicamera system, contrasting with manual measurement. This system is useful objective tool for medical tasks solution and further investigations are required in order to confirm effectiveness in orthodontic patients care. Ill. 4, bibl. 10 (in English; summaries in English, Russian and Lithuanian).