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1

Attachments of implant retained tissue supported denture under biting forces

Żmudzki J., Chladek W., Krukowska J.

Archives of Computational Materials Science and Surface Engineering

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2009

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Vol. 1, nr 1

13-20

EN

Purpose: In implant retained soft tissue supported type dentures functioning of attachments, presented by their producers as mechanically bio-compatible because of the ensured freedom of rotational displacements is accompanied by numerous problems that seem to be caused by excessive bearing of occlusal loads. Design/methodology/approach: For the purposes of attachments loadings evaluation, built was a threedimensional FEM model of a denture situated on an atrophic prosthetic foundation with joint supports assumed in the area of denture attachment to implants. Analysis of attachments loadings has been carried out under unilateral oblique occlusal forces of 100N in molars and incisors zones. Findings: Used methodology made it possible to determine attachments loading in a quantitative manner. In spite of free rotational movements implantological supports bear significant part of horizontal occlusal forces components, which reach the value of 66N during chewing processes. Research limitations/implications: Examined was only the most commonly used type of attachments. Hence, further studies, apart from constrains enabling rotational movements introduced should be also an axial compliance which is already offered by some types of attachments, and which additionally enables sedimentation of the denture towards the axes of implants. Practical implications: Analysis of loadings related to implantological attachments in case of assuming only a vertical component of occlusal forces leads to a significant underestimation of implantological supports loads values. In the presented analysis, taking into account the influence of the obliquely acting occlusal forces that occur in real chewing conditions, it has been proved that freedom of rotational movements of overdenture's attachments does not allow to use the natural supports of mucous membrane. That explains the reason of attachments and acrylic resin dentures damages, as well as the significant number of lost implants of upper denture resulting from biomechanical causes. In clinical practice, achieved should be the most anterior implants' placement, and especially in case of flat ridges because of the lack of any bearing surface. Originality/value: Determined loadings of supports might constitute a starting point for further biomechanical evaluation of attachments solutions that function according to similar principles, without the necessity of building complex models of the whole system.

2

Loading of overdenture attachments under simulated biting forces

Żmudzki J., Chladek W., Krukowska J.

Archives of Materials Science and Engineering

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2008

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Vol. 32, nr 1

33-36

EN

Purpose: The basis for effectiveness evaluation of over-denture attachments is the determination of loads on supports, and denture mobility. In cases of denture stabilized on two prosthetic supports, for most of the attachments constructions that are available on the market, the margin of dentures mobility is limited to rotation around axes of the attachments. Design/methodology/approach: Determining attachments loadings during bearing of biting forces that accompany chewing processes was carried out by means of Finite Element Method model analysis. A three-dimensional model of a denture supported on mucous membrane and joint supports assumes to be fixed in places of denture anchoring to implants. This model was loaded on one side with unilateral oblique 100 N force at molars zone. Findings: Maximum loading at pillar accompanies biting forces acting in a lateral direction toward buccal side. Research limitations/implications: Researches were carried out exclusively for attachments not showing any resilience in any direction, without any rotational constrains. Hence, in further researches, at the first place, determined should be the influence of the vertical resiliency used in some of the commercial attachments on loads bearing. Practical implications: Appropriate determining of loadings levels on over-denture attachments, requires necessarily that the oblique biting forces will be taken into account. In case of an assumption of only vertically oriented biting forces, there is a significant underestimation of the most dangerous horizontal loadings of prosthetic supports. Originality/value: Presented displacements of denture and pillars loading as vertical and horizontal reactions causing pillar bending and leverage at the bone, constitute a starting point for evaluation of denture’s behavior and strength estimation of analyzed types of attachments for implants and the surrounding bone.

3

Estimation of stresses in layers of dentures' relining materials

Żmudzki J., Chladek W., Krukowska J.

Archives of Materials Science and Engineering

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2008

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Vol. 30, nr 1

21-24

EN

Purpose: Durability tests of materials relining dentures should be carried out in conditions reflecting the real loading that accompanies bite force transmission. The influence of geometry resulting from a denture foundation shape on real stresses in relining has not been so far found. Design/methodology/approach: Using FEM modeling, identified were the stress levels in relining layers in conditions reflecting biting loading for two opposite cases of bone foundation atrophy. Findings: The equivalent Huber-Mises` stresses have not reached their critical values, although tangential stresses on the interfacial where relining is bonded with denture base have reached 440kPa, which, for some of the commercial types of relining denotes the bonding strength. Research limitations/implications: The linear elastic mechanical characteristics were assumed. Hence, during further research, taken into account should be the “stiffening” of characteristics in the upper loadings range, which is typical for silicones. Practical implications: In case of a convex foundation the biggest danger will be caused by any bond defects occurring in the central area because in that area shear of bond has reached the highest values. Originality/value: Values of stresses components identified in this paper reflect the real shear conditions of relining bonding with denture base and might constitute a determinant for strength tests.

4

Effort changes of lower complete denture material caused by relining

Żmudzki J., Chladek W., Krukowska J.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 2

79-82

EN

Purpose: Influence of dentures relining on saddles material effort in case of bone foundation not affected by any atrophic changes has been examined. Design/methodology/approach: Stresses levels in material of denture saddles bearing structure have been determined for any cases where alveolar ridges of mandible are well preserved. This research has been carried out in simulated conditions of biting loads, by means of a FEM. Compared were not-relined vs. relined saddles for two variants of bottom denture saddles margins, i.e. ended smoothly and with an extension that increases the amount of material of the bearing structure. Analyzed was also the influence on deformability of relining layers. Findings: Equivalent Huber-Misses stresses on a good saddles surface in case of a not-relined denture have slightly exceeded the level of 2 MPa, whereas in case of a relined denture with a soft margin they have reached 4 MPa; and for variant of relined denture with extended margin they reached a level of 14 MPa. Modulus of elasticity of the relining has not influenced significantly the effort of saddles material. Research limitations/implications: Assumed were vertical loading forces of 100 N simplified denture geometry without separating any complex shapes of artificial teeth. Practical implications: Increase of the bearing surface of relined saddles by means of extended margins results in stress concentration. Hence, attempts should be made to form the margins and teeth profiles changes at their base smoothly. All micro damages in endangered areas of saddles’ margins should be removed. Originality/value: Relining of low dentures’ saddles in a well preserved bone foundation does not directly result in excedance of allowable stress levels for prosthetic acrylic resins. Hence, the causes of failures should be sought in the impact of geometrical notches, or potentially existing damages that initiate degradation processes.

5

Stress distribution in anchoring regions of posts cooperating with overdentures

Chladek W., Chladek G., Krukowska J., Lipski T.

Acta of Bioengineering and Biomechanics

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2005

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Vol. 7, nr 1

35-45

EN

The paper presents the results of model research of mechanical compatibility of selected overdenture structures. The tests based on finite elements method were conducted on flat models reflecting the areas of posts anchoring m a sagittal piane. The reference point was the structure of a prosthesis seated on ball-and-socket joints secured in tooth roots. As altemative solutions, dentures placed on two cylindrical implants supporting ball-and-socket joints were compared with a denture attached to a joint which consisted of a straight axis bar and an elastic clip as well as with a denture supported by a joint of elevated retention, built of a doubly bent axis bar and three elastic bar clips. Taking advantage of the MES Algor program functions, the diverse materiał structures of the systems investigated were modelled. Next. the reduced stresses and principal maximum stresses generated m osseous tissues, in the implants anchoring area. were determined. The value of the mechamcal stimulator decisive to the osseous tissue remodelling was assumed as au evaluatiou criterion. It was assumed that making use of patient's own tooth roots to attach implants IS an optimal solution which, in terms of mechanics, IS practically identical to the alveolodental ligament of a healthy tooth. The application of the other methods of implanted prosthesis attachment always creates a risk of undesirable changes, mostly in the upper area of post insertion into the osseous tissue. The least favourably, in the light of stresses comparison, looks the joint of a doubly refracted axis, where the probability of adverse changes of the osseous tissue in a short time is high. This indicates the necessity to carry on words in order to improve this solution characterized by good retention.

6

Wpływ pola magnetycznego o różnej charakterystyce fizycznej na ciśnienie tętnicze krwi u chorych z zespołami bólowymi kręgosłupa i współistniejącą chorobą nadciśnieniową

Miecznik A., Czernicki J., Krukowska J.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2001

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Vol. 7, nr 1-2

9-13

PL

W terapii pacjentów z zespołami bólowymi kręgosłupa stosuje się zabiegi magnetoterapii i magnetostymulacji. Autorzy ocenili wpływ tej terapii na ciśnienie tętnicze krwi w grupie 64 pacjentów z zespołami bólowymi kręgosłupa i współistniejącą chorobą nadciśnieniową. Uzyskane wyniki wskazują na efekt hipotensyjny zabiegów magnetostymulacji.

EN

In therapy patients with back pain syndromes are used measures of magnetotherapy and magnetostimulation. In this study a trial was made to estimate the influence of this therapy in a group of 64 patients with back pain syndromes and hypertensive disease. The obtained data proved that there is a hypotension effect after magnetostimulation.