The aim of our study was to identify potential critical levels of implantation of an osseointegrated prosthesis for above-knee amputees. The implant used was the OPRA system. It was inserted in the femur at four different amputation heights, characterized by their residual limb ratios (0.299, 0.44, 0.58 and 0.73). The stress and strain distribution was evaluated in the bone-implant system during walking, considering a body mass of 100 kg. Considerably high stimulus (11,489 με) in the tissue near the tip was found at the highest implantation level. All models presented small non-physiologic stress values in the tissue around the implant. The results revealed that the implantation level has a decisive effect on bone-implant performance. Mainly, the analysis indicates adverse biomechanical conditions for implantations in very short residual limbs.

The effect of gamma irradiation and subsequent thermal treatment on the wear resistance and friction behavior of ultrahigh molecular weight polyethylene (UHMWPE) has been studied. Irradiation of the polymer was performed using a 60Co γ-emitter at laboratory temperature. Radiation dose 50 kGy was applied. Some irradiated samples were thermally treated at 150˚C for period of 30 min. and then slowly cooled to room temperature. A linear reciprocating tribometer was used to investigate the wear behavior of UHMWPE against Co-Cr-Mo alloy. The tests have been performed in unlubrication conditions. An important increase in wear resistance of the modified UHMWPE in comparison with the original material was proved. Besides wear rate the selected mechanical characteristics (friction coefficient, Young’s modulus, yield strength, fracture strength, and hardness) of original and modified samples of UHMWPE have been determined.

The longitudinal prestrain of arteries facilitates their physiological function. Remodeling, adaptation and aging result in an age-dependent magnitude of the pretension. Although the phenomenon is known, detailed statistics, especially for human arteries, are lacking. This study was designed to propose the regression model capable of estimating the prestrain of the human abdominal aorta. The length of the abdominal aorta before, l, and after excision from the body, L, the diameter, heart weight, thickness of left ventricle and degree of atherosclerosis were collected in autopsies of 156 male cadavers of known age. Longitudinal prestrain was quantified by means of the stretch ratio λ=l/L. Statistical analysis revealed significant dependence between age, prestrain, diameter and atherosclerosis, which were best fitted to the power law equation. Longitudinal prestretch reduced with age significantly; λmean=1.30±0.07 for age<30 (n=29), whereas λmean=1.06±0.03 for age>59 (n=31) with p-value<0.0001. Raw data gave linear correlation coefficients as follows: λ-age (R=-0.842); l-age (R=0.023); L-age (R=0.476); (l-L)-age (R=-0.811). It was concluded that longitudinal prestrain decreases nonlinearly with age and both age and diameter are suitable predictors of the prestrain. Data suggests that unloaded length elongates with age in contrast to the elastic retraction.

It is a well-known fact that the length of an artery in situ and the length of an excised artery differs. Retraction of blood vessels is usually observed. This pre-tension plays crucial role in arterial biomechanics. It augments an artery wall load-bearing capacity. This paper presents the longitudinal pre-strain of the human aorta as an index of human age. The length of abdominal aortas was measured during autopsies before and after segment resection. The longitudinal pre-strain was calculated in 130 donors; 100 male and 30 female bodies. The pre-strain was defined as the ratio between in situ length and the length after the excision. The mean pre-strain was found to be 1.18±0.10 for male and 1.14±0.10 for female sample (mean±standard deviation). The age in the male group was 41.6±15.9 years; and 47.7±17.7 years in the female group. Statistical analysis revealed the correlation coefficient between age and pre-strain r=−0.821 and r=−0.839 in male and female group, respectively. The analysis also confirmed close correlation between aortic circumference and age; and between circumference and pre-strain. Linear and power law regression equations were employed and prediction intervals were computed. The power law estimates the age more accurately than linear one model. Nevertheless, especially for small values of the pre-strain (aged individuals) the linear model can be advantageous.

The intent of this study was to evaluate elastic modulus of three dental filling composites. NanoDMA was focused on mechanical properties of upper irradiated layers of the specimens and on deeper layers where the intensity of polymerization radiation decreased. The nanoindentation testing was performed using a Hysitron's TriboLab (R). Poisson's ratios of composites were obtained by ultrasonic measurement of mechanical properties of the same materials. First observation showed decrease in modulus due to light absorption.

The intent of this study was to evaluate elastic modulus of different dental filling composites (Filtek (TM) Silorane, Filtek (TM) Supreme XT, Charisma). Nanoindentation was focused on mechanical properties of upper irradiated layers of the specimens and on deeper layers where the intensity of polymerization radiation decreased. In order to observe effect of time on indentation modulus different time intervals between nanoindentations of specimens were determined as follows: 1 hour, 1 day, 1 week and 1 month after specimen manufacturing. Static and dynamic analyses were performed using a Hysitron's TriboLab. Each tested material presented significant increase in modulus after 1 week and moderate decrease in the following days. Lower intensity of radiation due to light absorption caused moderate decrease of elastic modulus. The viscoelastic properties of composites are weak.

The intention of this study was to determine elastic modulus of different resin-composite filling materials for the use in FEM analyses and to observe changes of mechanical properties in different time after polymerization. Nanoindentation was chosen as suitable non-destructive method for elastic modulus determinations. Each tested material presented changes in modulus in dependence on time after specimens moulding. We conclude that elastic modulus of tested materials vary in time. These changes can be explained by the setting reaction of polymer matrix and filling particles after polymerization.

For patients with giant cell tumor (GCT) of the distal femur and/or proximal tibia, a limb-salvage reconstruction and tumor total knee endoprosthesis (TICE) plays a very important role. There exist several types of TKE, varying not only in design but also in kinematics and functional outcome. This paper presents results of dynamic finite element analysis of tumor TKE made according to the ISO 14 243. Hinge type endoprosthesis has been loaded by variety of forces and kinematic boundary conditions to find the most critical areas of the TKE. The analysis has been focused especially on plastic bushings extremely loaded during the movement. Suitability of PEEK for this part has been proven. Presented results are useful for following development of tumor total knee endoprosthesis.

Multifunctional wear and corrosion resistant decorative nanostructured carbon-base coatings were prepared by PACVD (Plasma Assisted Chemical Vapour Deposition) method on steel substrates. As the multifunctional coating the carbon-base, particularly DLC (Diamond-Like Carbon) nanolayer, was chosen. For the deposition of adherent DLC coating on steel substrate a very thin Si-O-C interlayer was applied in some cases. Deposition of DLC coating and Si-O-C interlayer was performed using dc plasma without additional heating and with the HMDSO (hexamethyldisiloxane) and methane as precursors. During coating growth with increasing of thickness of DLC nanolayer the colour of nanolayer is changed. Whole spectrum of attractive colours is obtained, what is possible to use to decorative purposes. Effect of film thickness on colour is following: The reference specimen (bare stainless steel) has a bright metallic sheen. In the order of increasing thickness, the DLC films produced by PACVD have colours as follows: dark violet at ~75 nm; medium blue at ~130 nm; golden light at ~170 nm; deep rose pink at ~240 nm; golden brown at ~320 nm; and soot black at ~1200 nm. Decorative coatings must be adherent and hard for good wear resistance. Adhesion was tested by scratchtester and microhardness was determined by nanoindentation. The microhardness data were thickness-dependent, influenced by substrate. The highest measured value was 23 GPa. Tribology of the coatings was assessed by wet friction tests.

Our team-work was focused on dental filling composites investigation with a view to prolong lifetime and minimize probability of failure. The most common failure types were filling fractures, secondary caries and losses of filling. Main reason for failure was stress incidence in filling and adhesive layer causing weakening of tooth-adhesive-composite interface. Stress value could be mathematically analyzed using finite element program. This analysis required knowledge of exact material properties. The goal of work was to determine values of composite elastic modulus by different experimental method: simple tensile test, three-point bending test, nanoindentation test.

The aim of this paper was to claim or disclaim if the jaw movement differs significantly between right and left side among young physiological subjects. Relative displacement of the temporomandibular (TM) disc and the mandible during mouth opening was determined. The movement of the TM disc was studied using a magnetic resonance imaging (MRI) quasi-static scan sequence with a customized mono-directional "spreader" device. A number of sagittal static images in revolved sections of the temporomandibular joint (TMJ) were obtained in various positions of jaw opening from 0 to 50 mm. The results provided a description of the TM disc displacements as a function of jaw opening. The anatomical marker movement data was observed with the assumption of fixed skull. Motions of the TM disc and the mandible were found out. The maximum average displacements of the mandible and the TM disc were about 16 mm (x-direction) and 6 mm (mean value) respectively at mouth opening of 50 mm. The maximum average rotation of the mandible was 32 degrees. While the movement of the mandible has already been published, though only for a small mouth opening, the behavior of the disc during the same movement has not been well depicted. The results of these measurements can be used for clinical diagnostics and also as inputs for finite element analysis (FEA).

Abstract — Common total knee endoprosthesis (TKE) consist of a metal femoral component and a tibial component (an UHMWPE plateau and its metal tray). Though metal in case of the femoral component can be replaced with the more progressive material like Zirconia [1] (the endoprosthesis developed with a contribution of our Laboratory of Biomechanics) a loading remains unchanged. For future development of actual endoprosthesis, a quality FE model seems to be a key-goal. While developing a dynamic model [2] of a lower limb focusing on the knee joint with the implanted endoprosthesis, every partial result is being verified. One of the most important characteristics of the endoprosthetic system using the UHMWPE plateau is contact pressure between the plateau and the femoral component. For the mechanical test serving for verification of contact pressures (formerly calculated by FEA) by means of pressure sensitive films, special jigs were designed for the femoral and the tibial component and the measurement up to 3000 N were made. Then using the single-purpose software, magnitudes and a distribution of a contact pressure were calculated and compared with FEM results. Since a geometric model of the endoprosthesis and a factory-made endoprosthesis seem not to be identical in shape of contact surfaces, a result comparison was very hard. Based on a position of a contact and its area we beg to conclude that the results are very promising.

Previous results shows high discrepancy between the peak hip contact stress measured experimentally and the peak contact hip stress estimated from mathematical models. In this study, a mathematical model which was previously verified in clinical studies, has been adapted to describe the influence of the local increase in cartilage thickness on the hip to the contact stress distribution. It is shown that a local increase of the hip cartilage thickness increases the hip contact stress in the region of thicker cartilage to the experimentally obtained level. However, the local variations in cartilage thickness do not considerably affect the overall stress distribution. It follows that although the mathematical model cannot predict local peaks of hip contact stress if the cartilage properties are not known, it provides an estimation of the contact stress distribution pattern that proves to be significant in the long-term prediction of the development of the hip.

The aim of a project of our Laboratory of Human Biomechanics, CTU in Prague engaging finite element analyzes of a human knee joint is to create a finite element model as detailed as possible of this joint including its total replacement. On the basis of previous simplified models [1] and all existing mechanical tests, including those using special films for contact pressure measurement, new model was developed using a Walter Modular (WM) knee endoprosthesis. Bone three-dimensional models were created by common means using freely available CT scans (Visible Human Project [2]). Since it was necessary to be able to edit the bone models in a CAD software a procedure to obtain such models was executed. In these form, they can be used also during a development of new types of WM system. As for the analysis it self, it was prepared for the knee in a full flexion as a static contact problem loaded by a single force equal to three-times body weight. Since the static problem does not correspond to the real joint, another work has to be made and it is a goal of one of the next model. Results of the presented work are useful for a comparison with the results of another authors and our former ones.

This paper deals with a knee joint endoprosthesis finite element analysis. Based on a three dimensional geometric model of a lower extremity, a mechanical axis of the limb was designed. This axis is important for several reasons. Firstly, the endoprosthesis was positioned due to its direction, secondly, boundary conditions was defined on its proximal and distal end and finally, the axis enabled reasonable simplification of the model which led to the time saving analysis while preserving principal features of the model like the natural boundary conditions or knee joint's degrees of freedom . Having this, one leg stance was simulated. Results of the analysis were encouraging for future models. Especially the choice of the mechanical axis was suitable and enabled a better distribution of contact pressures and stress on both femoral and tibial component compared to our former models. Also their magnitudes correspond better the manufacturer's experience and our findings. The stresses did not exceeded 30 MPa for the UHMWPE tibial plateau and 100 MPa for the femoral component. The contact pressures were lower than 40 MPa.

This paper deals with a simulation by means of finite element method of a natural lower limb after a knee joint arthroplasty in a full extension. Our last static model serving as a starting point for our future dynamic analysis is presented now. Aside a total knee endoprosthesis Medin Modulár provided by MedinOrthopedics, a.s., two long bones, femur and tibia were used. Compared with our former results, this model gives reduced stress and contact pressures values which were given by more realistic ankle and hip joint definition. Their distributions also correspond better the experimental findings. [Engineering of Biomaterials, 63-64, (2007), 6-7] CLINICAL AND HISTOLOGICAL RESULTS OF ACUPUNCTURE INFLUENCE ON ACUTE PYOINFLAMMATORY PROCESSES DEVELOPEMENT IN SOFT TISSUES. EXPERIMANTAL CASE Y.M. Kazakova, I.O. Pohodenko-Chudakova, E.I. Parhovtchenko Belarussian Collaborating Centre of EACMFS, Belarussian State Medical University, Minsk, Belarus Pushkin av. 33 – 239; PO BOX 190; 220092 Minsk, Belarus E-mail: ip-c@yandex.ru [Engineering of Biomaterials, 63-64, (2007), 8-9] RESULTS OF LASER ACUPUNCTURE INFLUENCE ON LOCAL CLINICAL AND LABORATORY INDICES AFTER DENTAL IMPLANTATION IN EXPERIMENT A.P. Pilipenko, I.O. Pohodenko-Chudakova Belarussian Collaborating Centre of EACMFS, Belarussian State Medical University, Minsk, Belarus, Pushkin av. 33 – 239; PO BOX 190; 220092 Minsk, Belarus E-mail: ip-c@yandex.ru [Engineering of Biomaterials, 63-64, (2007), 9-10] RESULTS OF ACUPUNCTURE IN COMPLEX THERAPY FOR PATIENTS WITH ACQUIRED DETTECTS OF LOWER JAW ON THE ORAL FLUID MICROCRYSTALLIZATION FINDINGS I.O. Pohodenko-Chudakova, A.O. Sakadynetz Belarussian Collaborating Centre of EACMFS, Belarussian State Medical University, Minsk, Belarus, Pushkin av. 33 – 239; PO BOX 190; 220092 Minsk, Belarus E-mail: ip-c@yandex.ru [Engineering of Biomaterials, 63-64, (2007), 11-12] PROGNOSTIC CRITERIA FOR DEVELOPMENT OF CHRONIC ODONTOGENOUS SINUSITIS OF MAXILLARY SINUS I.O. Pohodenko-Chudakova, А.V. Surin Belarussian Collaborating Centre of EACMFS, Belarussian State Medical University, Minsk, Belarus, Pushkin av. 33 – 239; PO BOX 190; 220092 Minsk, Belarus E-mail: ip-c@yandex.ru [Engineering of Biomaterials, 63-64, (2007), 12-13] THE STRUCTURE AND IMMOBILIZATION ACTIVITY OF POLYVINYLPYRROLIDONE CROSS-LINKED COPOLYMERS Oleg Suberlyak, Volodymyr Skorokhoda, Nataliya Semenyuk Lviv Polytechnic National University, Bandera St. 12, Lviv, Ukraine; e-mail: suberlak@polynet.lviv.ua [Engineering of Biomaterials, 63-64, (2007), 14-15] NANO-SIZED MICELLES FORMED BY SELF-ASSEMBLING OF POLYLACTIDE/POLY(ETHYLENE GLYCOL) BLOCK COPOLYMERS IN AQUEOUS SOLUTIONS Liu Yang, Zhenxian Zhao, Jia Wei, Suming Li 1 Department of Materials Science, Fudan University, Shanghai 200433, China 2 Max Mousseron Institute on Biomolecules, UMR CNRS 5247, Research Center on Artificial Biopolymers, Faculty of Pharmacy, University Montpellier I, 34060 Montpellier, France e-mail: lisuming@univ-montp1.fr [Engineering of Biomaterials, 63-64, (2007), 16-18] HIGH-HYDROPHILIC MEMBRANES FOR DIALYSIS AND HEMODIALYSIS Oleg Suberlyak, Jourij Melnyk, Nataliya Baran Lviv Polytechnic National University, Bandera St. 12, Lviv, 79013, Ukraine e-mail: suberlak@polynet.lviv.ua [Engineering of Biomaterials, 63-64, (2007), 18-19] IMMOBILIZATION OF COLLAGEN – AN EFFECTIVE METHOD OF IMPROVING CELL ADHESION ON POLYMERIC MATERIALS Elżbieta Pamuła, Anna Ścisłowska-Czarnecka 1 AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Department of Biomaterials, Al. Mickiewicza 30, 30-059 Kraków, Poland 2 Academy of Physical Education, Faculty of Anatomy, Al. Jana Pawła II 78, 31-571 Kraków, Poland Abstract Surface properties of poly(L-lactide-co-glycolide) (PLG), and two reference materials: hydrophobic polystyrene (PS) and hydrophilic tissue culture polystyrene (TCPS) were modified by collagen adsorption. The morphology of the obtained collagen film was observed by using atomic force microscopy. On PLG and TCPS collagen layer was uniform, while on PS collagen formed isolated patches. The differences in supramolecular organization of collagen were due to differences in surface wettability. The behaviour of L929 fibroblasts incubated on all raw and collagen-modified surfaces was then evaluated. The best adhesion and spreading of cells, as expected, were observed on TCPS. Collagen adsorbed on PLG and PS considerably improved adhesion and spreading of fibroblasts.Surface properties of poly(L-lactide-co-glycolide) (PLG), and two reference materials: hydrophobic polystyrene (PS) and hydrophilic tissue culture polystyrene (TCPS) were modified by collagen adsorption. The morphology of the obtained collagen film was observed by using atomic force microscopy. On PLG and TCPS collagen layer was uniform, while on PS collagen formed isolated patches. The differences in supramolecular organization of collagen were due to differences in surface wettability. The behaviour of L929 fibroblasts incubated on all raw and collagen-modified surfaces was then evaluated. The best adhesion and spreading of cells, as expected, were observed on TCPS. Collagen adsorbed on PLG and PS considerably improved adhesion and spreading of fibroblasts. [Engineering of Biomaterials, 63-64, (2007), 20-23] WPŁYWU ŻELU WYBIELAJĄCEGO Z NADTLENKIEM MOCZNIKA NA POWIERZCHNIĘ SZKLIWA BADANIA ZA POMOCĄ MIKROSKOPU SIŁ ATOMOWYCH (AFM) AN ATOMIC FORCE MICROSCOPY STUDY ON THE EFFECT OF CARBAMIDE PEROXIDE BLEACHING GEL ON ENAMEL SURFACE Dorota Kościelniak, Elżbieta Pamuła 1 Uniwersytet Jagielloński, Collegium Medicum, Pracownia Stomatologii Dziecięcej IS CMUJ ul. Montelupich 4, 31-155 Kraków 2 Akademia Górniczo-Hutnicza, Wydział Inżynierii Materiałowej i Ceramiki, Katedra Biomateriałów, Al. Mickiewicza 30, 30-059 Kraków 1 Department of Pedodontics, Institute of Stomatology, Collegium Medicum, Jagiellonian University, ul. Montelupich 4, 31-155 Kraków, Poland 2 AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Department of Biomaterials, Al. Mickiewicza 30, 30-059 Kraków Streszczenie W pracy oceniono wpływ żelu wybielającego zawierającego 20% nadtlenek mocznika na powierzchnię szkliwa zęba ludzkiego. Przy użyciu mikroskopu sił atomowych (AFM) zarejestrowano obrazy topograficzne szkliwa z powierzchni policzkowej zęba bez kontaktu jak i po kontakcie z żelem wybielającym. Badania wykazały, że 48-godzinne wybielanie nie wpływa w istotny sposób na topografię szkliwa i jego chropowatość. Parametry topograficzne takie jak: średnia chropowatość powierzchni, chropowatość skuteczna i średnia wysokość elementów topograficznych szkliwa po procesie wybielania były podobne do parametrów próbki kontrolnej. Abstract The effect of bleaching gel containing 20% carbamide peroxide on human enamel surface was evaluated. Topography images of the control and test samples located on the buccal surface of the same tooth were recorded with the use of an atomic force microscope (AFM). AFM evaluation demonstrated that 48-hour bleaching did not significantly affect topography and roughness of the enamel. Topographical parameters such as average roughness, root mean square roughness and average height were similar for both control and test surfaces of the enamel. [Inżynieria Biomateriałów, 63-64, (2007), 24-27] [Engineering of Biomaterials, 63-64, (2007), 24-27] DŁUGOCZASOWA KOROZJA STOPÓW REX 734 I PANACEA P558 W ROZTWORACH 0.5 M NaCl I TYRODE’A LONG-TIME CORROSION OF REX 734 AND PANACEA P558 ALLOYS IN 0.5 M NaCl AND TYRODE’S SOLUTIONS Barbara Burnat, Tadeusz Błaszczyk, Andrzej Leniart, Henryk Scholl, Leszek Klimek 1 Uniwersytet łódzki, Wydział Fizyki i Chemii, Katedra Chemii Ogólnej i Nieorganicznej, 90-136 Łódź, Narutowicza 68 2 Politechnika Łódzka, Wydział Mechaniczny, Instytut Inżynierii Materiałowej, Zakład Inżynierii Biomedycznej, 90-924 Łódź, Stefanowskiego 1/15 e-mail: burnat@op.pl 1 University of Lodz, Faculty of Physics and Chemistry, Department of General and Inorganic Chemistry, 90-136 Lodz, Narutowicza 68 2 Technical University of Lodz, Faculty of Mechanical Engineering, Division of Biomedical Engineering, 90-924 Lodz, Stefanowskiego 1/15 E-mail: burnat@op.pl Streszczenie Przeprowadzono badania długoczasowej korozji dwóch biomedycznych stopów typu Fe-Cr-Mo: Rex 734 i Panacea P558 w roztworach 0.5 M NaCl i Tyrode’a, w temperaturze ciała ludzkiego 37C (310 K). Czas kontaktowania się próbek stopów z roztworami wynosił 84 dni (ok. 3 miesiące). Stwierdzono, że dla wszystkich badanych próbek zarówno potencjały korozyjne, opory polaryzacyjne jak i szybkości korozji stabilizują się w końcowych 40. dniach. Inaczej zmieniają się w czasie eksperymentu charakterystyki impedancyjne. Wyniki atomowej spektroskopii absorpcyjnej roztworów korozyjnych pokazały, że korozja badanych stopów w swobodnym potencjale korozyjnym zachodzi równomiernie. Abstract Long-time corrosion of two biomedical Fe-Cr-Mo alloys: Rex 734 and Panacea P558 was investigated in 0.5 M NaCl and Tyrode’s solutions at human body temperature of 37C (310 K). Samples of alloys were in contact with corrosion solutions within 84 days (ca. 3 months). It was stated that for all investigated samples both corrosion potentials, polarization resistances and corrosion rates were stabilized in last 40 days. In a different manner impedance characteristics changed during experiment. Results of atomic absorption spectroscopy of corrosion solutions after 84 days showed that corrosion processes at free corrosion potentials proceed as uniform corrosion. [Inżynieria Biomateriałów, 63-64, (2007), 28-31] [Engineering of Biomaterials, 63-64, (2007), 28-31] WPŁYW PROSZKÓW WĘGLOWYCH NA LUDZKIE KRWINKI BIAŁE INFLUENCE OF CARBON POWDER PARTICLES ON HUMAN NEUTROPHILS Katarzyna Bąkowicz-Mitura, Małgorzata Czerniak-Reczulska Zbigniew Baj 1 Zakład Inżynierii Biomedycznej, Instytut Inżynierii Materiałowej, Politechnika Łódzka ul. Stefanowskiego 1/15, 90-924, Łódź 2 Zakład Patofizjologii i Immuno

Clinical observations and mathematical models show that dental implants are influenced by the magnitude of loading. Therefore, the knowledge of mandible movement during mastication is important to assess occlusal and masticatory force vectors. The purpose of this study was to detect the path of movement of the lower jaw and to distinguish stages of mastication, duration of bolus processing and peak amplitude of mastication. Motion analysis was used to record three-dimensional mandible movements. Individualized sensors were rigidly attached to the mandible of 51 study participants. At the beginning of the measurement, all subjects were asked to move the mandible in extreme positions (maximal opening and maximal lateral movements). Then, each subject masticated a bite of hard and soft food. Duration of bolus mastication and peak amplitude of mastication movement in mesio-distal, cranio-caudal and vestibulo-oral axes related to peak amplitude of marginal movements were evaluated for each subject. The chewing record of each subject was divided into three phases (chopping, grinding and swallowing), and the duration of mastication and number of closing movements were evaluated. Results of this pilot study suggest that masticatory movements vary in individuals. Relationships to directions and magnitudes of acting chewing force should be more precisely examined since transversally acted forces during grinding are important factors in implant overloading.

OBJECTIVE:Clinical observations and mathematical models show that dental implants are influenced by the magnitude of loading. Therefore, the knowledge of mandible movement during mastication is important to assess occlusal and masticatory force vectors. The purpose of this study was to detect the path of movement of the lower jaw and to distinguish stages of mastication, duration of bolus processing and peak amplitude of mastication.METHOD:Motion analysis was used to record three-dimensional mandible movements. Individualized sensors were rigidly attached to the mandible of 51 study participants. At the beginning of the measurement, all subjects were asked to move the mandible in extreme positions (maximal opening and maximal lateral movements). Then, each subject masticated a bite of hard and soft food. Duration of bolus mastication and peak amplitude of mastication movement in mesio-distal, cranio-caudal and vestibulo-oral axes related to peak amplitude of marginal movements were evaluated for each subject. The chewing record of each subject was divided into three phases (chopping, grinding and swallowing), and the duration of mastication and number of closing movements were evaluated.RESULTS:The findings of this pilot study suggest that masticatory movements vary in individuals. Bolus character influences the process duration, but not the frequency of closing movements. Neither gender nor age had any influence on either the time or frequency of bolus processing.CONCLUSION:Relationships to directions and magnitudes of acting chewing force should be more precisely examined since transversally acted forces during grinding are important factors in tooth/implant overloading.

The computer system for quantitative determination of musculoskeletal geometry from computer tomography (CT) images has been developed. The computer system processes series of CT images to obtain three-dimensional (3D) model of bony structures where the effective muscle fibres can be interactively defined. Presented computer system has flexible modular structure and is suitable also for educational purposes.