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Biomedical subjects

K Tanne

Publications and source records attributed to K Tanne.

At least 127 records · Page 7Linked to original sources
PubMed1990

[Changes in efficiency of orthodontic tooth movement resulting from differences in bracket materials].

The distance of distal movement of the lower canine was measured, using metal tooth with metal bracket and three types of ceramic bracket (polycrystal alumina x 2, zirconia x 1). Sizes of the wires used in this experiment were 0.018" round, 0.016" x 0.022" and 0.17" x 0.022". The bracket slot and the wire surface employed in the experiment were observed by use of stereoscopic microscope and S.E.M. The following results were obtained. 1. The distance of tooth movement with three types of ceramic bracket was significantly less than that with the metal bracket. 2. Rate of decrease in tooth movement with three types of ceramic bracket ranged from 30% to 60% in comparison with the metal bracket. 3. The wire surface was obviously scratched by the ceramic brackets, whereas slight scratch was observed on the wire with the metal bracket. 4. The distance of tooth movement decreased associated with an increase of wire size. 5. The distance retracted from the cuspal position was less than that from the cervical point. It was shown that efficiency of tooth movement was significantly reduced by the use of ceramic brackets in comparison with the metal bracket. This result seems to be caused by the frictional resistance between the wire and ceramic bracket. It is suggested that refinement of ceramic brackets, slot edge and surface in particular, would produce more efficient and desirable tooth movements in clinical orthodontics.

Ceramics↗
PubMed1989

Biomechanical effect of anteriorly directed extraoral forces on the craniofacial complex: a study using the finite element method.

This study was designed to investigate the biomechanical effect of protractive maxillary orthopedic forces on the craniofacial complex by use of the three-dimensional finite element method (FEM). The three-dimensional FEM model was developed on the basis of a dry skull of a young human being. The model consisted of 2918 nodes and 1776 solid elements. Eighteen cranial and facial sutural systems were integrated in the model. An anteriorly directed 1.0-kg force was applied on the buccal surfaces of the maxillary first molars in both a horizontal parallel direction and a 30 degree obliquely downward direction to the functional occlusal plane. The nasomaxillary complex showed a forward displacement with upward and forward rotation in a horizontal protraction case, whereas a downward force produced almost translatory repositioning of the complex in an anterior direction. High stress levels were observed in the nasomaxillary complex and its surrounding structures. However, the pattern of stress distributions within the complex was different in two force systems. A downward protraction force produced relatively uniform stress distributions, indicating the importance of the force direction in determining the stress distributions from various orthopedic forces.

Biomechanical Phenomena↗
PubMed1989

Effects of directions of maxillary protraction forces on biomechanical changes in craniofacial complex.

The purpose of this study was to investigate the effect of directions of extraoral maxillary protraction forces on biomechanical changes in the craniofacial complex, using the three-dimensional finite element method (FEM). A three-dimensional FEM model was developed on the basis of a young, human dry skull. The model consisted of 2918 nodes and 1776 solid elements. An anteriorly directed 1.0 Kg force was applied to the buccal surface of the maxillary first molar in directions varying from -90 to 90 degrees to the occlusal plane. The displacement pattern of the entire craniofacial complex was evaluated. Further, the stress distributions were determined in three transverse planes associated with parallel, and 30 degrees upward and downward forces. As the force direction was more upward, repositioning of the craniofacial complex became larger in both the horizontal and vertical directions. Displacements were most translatory in loading with the forces applied in the directions ranging from -45 to -30 degrees to the occlusal plane. High stress levels were observed in the nasomaxillary complex and its surrounding structures. However, the patterns of stress distribution within the complex were different for three loading conditions. A downward protraction force produced the most uniform stress distribution. It is shown that the force direction plays an important role in determining the repositioning and the stress distributions in the craniofacial complex.

Biomechanical Phenomena↗
PubMed1989

[Mechanical properties of nickel-titanium alloy wire developed by the diffusion method].

The present study was conducted to investigate mechanical properties of the nickel-titanium (Ni-Ti) alloy wire developed by the diffusion method, in comparison with the previous Ni-Ti wires. Two types of the wire, work hardening and super elastic wires, were used for three experiments; three-point bending test, tension test and torque test. The following findings were obtained. 1. A newly developed work hardening wire exhibited lower force level with a generous reduction of force at various wire deflections, in comparison with the previous work hardening Ni-Ti wires. It was also found that tension strength and extension ratio of this wire were greater, and its modulus of longitudinal elasticity was smaller than those of the previous wires, indicating high resistibility to breakage. 2. A super elastic wire, developed by the diffusion method, showed similar pattern of force reduction associated with varying wire deflections, although magnitude of force was slightly larger than those of the previous super elastic wires. 3. An interesting finding was that force and its reduction with various deflections were varied by controlling how the wire was ligated onto a bracket, which was more obvious in the work hardening type of the present Ni-Ti wire. 4. Magnitudes of force exerted by Ni-Ti wires were around 200 gf at a deflection of 2 mm with an interbracket distance of 7 mm, and seemed to be beyond an optimal orthodontic force for anterior teeth. A further refinement is expected in terms of improving mechanical properties and/or developing finer wires.

Animals↗
PubMed1989

Biomechanical responses of tooth associated with different root lengths and alveolar bone heights: changes of stress distributions in the PDL.

The purpose of the present study was to elucidate the nature of stress distributions in the PDL varied by different root lengths and alveolar bone heights. A three-dimensional model of the upper central incisor was constructed for the finite element method (FEM). The model was modified to produce various root lengths and alveolar bone heights. A lingually directed 100 g horizontal force was applied at a point on the labial crown surface. Stress distributions were determined in the center of the PDL for various apicogingival levels. Stress levels in the PDL gradually decreased with a longer root. Rates of changes in stress levels to those with an original root length were approximately 1.5 at maximum and 0.8 at minimum. Patterns of stress distributions were varied by different alveolar bone heights in both the qualitative and quantitative aspects; i.e., apicogingival level of stress transition shifted more apical, and stress levels also increased following a reduction of the alveolar bone in the apicogingival direction, approaching about eight times with a half alveolar bone height as the original. It is found that the root length and alveolar bone height affect stress distributions in the PDL. Thus, it is shown that an orthodontic force application should be determined on the basis of anatomical variations in root length and alveolar bone height to induce an optimal stress level in the PDL, which is a key to desirable tooth movement.

Alveolar Process↗
PubMed1989

Longitudinal study on craniofacial growth following Le Fort I maxillary osteotomy in adolescent monkeys.

The present study was conducted to investigate the effects of Le Fort I maxillary osteotomy on craniofacial growth in adolescent monkeys. Twenty monkeys were used, of which eight served as control and twelve for experiment. All monkeys received tantalum implants, whereas experimental monkeys underwent Le Fort I osteotomy. Serial lateral cephalograms were taken before and immediately after surgery, and thereafter every month. Craniofacial growth was investigated by evaluating both repositionings of anatomical landmarks and implants, and dimensional changes. No significant differences between the experimental and control groups were observed in midfacial growth. Maxillary growth was not significantly affected excluding the posterior region of the maxilla. Condylar growth of the mandible was significantly influenced, and the overall length of the mandible in the experimental group was much less as compared to the controls. However, the length of the body of the mandible was not significantly affected, indicating a catch up growth of the mandible. It is shown that craniofacial growth is somewhat retarded, however, the maxilla and mandible experience harmonious growth even after surgery. Thus, it is indicated that the maxillary osteotomy is applicable to growing patients as well as adults, in terms of the craniofacial growth after surgery.

Animals↗
PubMed1989

Effect of moment to force ratios on stress patterns and levels in the PDL.

This study was conducted to investigate the effect of moment to force (M/F) ratios on stress distributions in the PDL. Three-dimensional finite element method (FEM) was applied to stress analysis, using a three-dimensional model of the upper central incisor. Five force systems were established to produce different M/F ratios with a constant 100 g lingual force and/or varying labial crown couples, applied at a point on the labial crown surface, 4 mm gingival to the incisal edge. Stresses were determined in the center of the PDL for eight apicogingival levels and at sixteen points around the root. Stress patterns and levels in the PDL changed in response to varying M/F ratios, however, stress values were invariable at the level of the center of resistance. M/F ratio for translation of a tooth produced the most uniform pattern of stress distributions and the minimum stress levels. It is found that the stress level induced in tooth translation is approximately 0.29 times as that in simple tipping of a tooth. Thus, it is shown that the M/F ratio is an important determinant for controlling the stress patterns and levels in the PDL and for achieving optimal tooth movement.

Bite Force↗
PubMed1989

[Stress distribution in the periodontal ligament induced by orthodontic forces. Use of finite-element method].

This study was designed to investigate the stress levels induced in the periodontal tissue by orthodontic forces using the three-dimensional finite element method. The three-dimensional finite element model of the lower first premolar was constructed on the basis of average anatomic morphology and consisted of 240 isoparametric elements. Principal stresses were determined at the root, alveolar bone, and periodontal ligament (PDL). In all loading cases for the buccolingually directed forces, three principal stresses in the PDL were very similar. At the surface of the root and the alveolar bone, large bending stresses acting almost parallel to the root were generally observed. During tipping movement, stresses nonuniformly varied with a large difference from the cervix to the apex of the root. On the other hand, in case of movement approaching translation, the stresses induced were either tensile or compressive at all occlusogingival levels with some difference of the stress from the cervix to the apex. The pattern and magnitude of stresses in the periodontium from a given magnitude of force were markedly different, depending on the center of rotation of the tooth.

Dental Stress Analysis↗
PubMed1988

Three-dimensional model of the human craniofacial skeleton: method and preliminary results using finite element analysis.

The purpose of this study was to develop a three-dimensional finite element model of the craniofacial skeleton using a dry human skull. The model consisted of 2918 nodes and 1776 solid elements, and was used to investigate the biomechanical effect of a distally directed orthopaedic force on the craniofacial complex. The force was applied at the level of the maxillary first molar. The results indicated that in response to the force system applied: the nasomaxillary complex displaces in a backward and downward direction and rotates in clockwise sense; the nasomaxillary complex, including the zygomatic bone, experiences high stress levels in comparison with those at the remaining bones; the stress distribution in the maxillary basal bone area is relatively uniform; and the stress distribution across the opposing surface of the bony margins of the sutures is non-uniform.

Biomechanical Phenomena↗
PubMed1988

Moment to force ratios and the center of rotation.

The purpose of this study was to investigate the relationship between moment to force (M/F) ratios and the centers of rotation by use of the finite element method (FEM). A three-dimensional FEM model was developed for the upper right central incisor on the basis of average anatomic dimensions. The center of resistance and centers of rotation were determined for varying M/F ratios applied at the midpoint of the crown. The center of resistance was located at 0.24 times the root length measured apical to the level of alveolar crest. The centers of rotation varied with the M/F ratios following a curve of hyperbola. The M/F ratio was -9.53 for root movement (Co at the incisal edge), -8.39 for translation, and -6.52 for tipping around the apex. It was found that even a small difference in the M/F ratios produced clinically significant changes in the centers of rotation.

Biomechanical Phenomena↗
PubMed1987

Longitudinal study of craniofacial growth in Macaca fascicularis.

This paper is an analysis of normal craniofacial growth in adolescent crab-eating macaques (Macaca fascicularis). Eight female adolescent monkeys were used in this study. Their individual craniofacial growth was studied for a 24-month period utilizing tantalum implants and roentgenographic cephalograms. Throughout the observation period, each monkey consistently showed a class I molar relationship with a good overjet and overbite. The amount of anterior displacement of the maxilla and the mandible was significantly dominant compared to the vertical displacements at every observation period. The midface exhibited a maxillary differential growth pattern in which the premaxilla displaced superiorly and the posterior maxilla moved inferiorly, resulting in a counterclockwise rotation of the entire maxilla. Growth of the lower anterior teeth and alveolar bone compensated for the incremental vertical spaces which were induced by superior displacement of the premaxilla and inferior repositioning of the chin. In addition, the amount of anterior displacement of the upper and lower anterior teeth were significantly larger than that of the premaxilla and the chin. The dentocraniofacial growth pattern in Macaca fascicularis was quite similar to that seen in Macaca mulatta.

Aging↗
PubMed1987

Three-dimensional finite element analysis for stress in the periodontal tissue by orthodontic forces.

This study was designed to investigate the stress levels induced in the periodontal tissue by orthodontic forces using the three-dimensional finite element method. The three-dimensional finite element model of the lower first premolar was constructed on the basis of average anatomic morphology and consisted of 240 isoparametric elements. Principal stresses were determined at the root, alveolar bone, and periodontal ligament (PDL). In all loading cases for the buccolingually directed forces, three principal stresses in the PDL were very similar. At the surface of the root and the alveolar bone, large bending stresses acting almost in parallel to the root were generally observed. During tipping movement, stresses nonuniformly varied with a large difference from the cervix to the apex of the root. On the other hand, in case of movement approaching translation, the stresses induced were either tensile or compressive at all occlusogingival levels with some difference of the stress from the cervix to the apex. The pattern and magnitude of stresses in the periodontium from a given magnitude of force were markedly different, depending on the center of rotation of the tooth.

Alveolar Process↗