4 Magnitude Stress Denture designing and the biomechanics

[00:00:00]assalamu alaikum and good day this video gonna explain regarding magnitude of stress and controlling in rpd design the last two learning outcomes will be covered factors influence the magnitude of stress removal partial denture and design considerations in controlling stress when we look for magnitude of stress to the environment teeth there are eight factors to be considered the factors are length of medical spine quality of support class flexibility class design length of class material use in club's construction surface characteristic of the abutment and lastly occlusal harmony moving on to the next slide we're gonna go through of these factors one by one what to be considered when we talk about length of identity span and quality of the wish support basically the longer edental span the longer the base and greater force transmitted to the abutment tools so larger wish actually capable to absorb stress as comparison to the small thin or knife-ish reach so broad range with parallel side will help stabilizing the danger against the lateral force in two considerations when we look for the healthy of the mucosa is actually capable of bearing a greater functional load so when we put into consideration of tax factors lateral extension saddle area for posterior edentulous should cover the buckle shaft the boundaries of parker shaft are external or be or line and lateral crest of the alveolar region it becomes the primary support as it parallel to the occlusal plane and composed of dense cortical bone and is relatively resistant to the force by denture moving on to the posterior extension it should extend cover the retromolar pad area it contains granular tissue loose alveolar cognitive tissue lower margin of the terracomanicularaphae fibers of the vaccinator and superior constructor and fiber of temporal tendon so the bone vine does not result secondary to the pressure associated with the denture so it becomes the primary support area ideally when we're talking about occlusal arrangement or akuza harmony it should be in harmony with the tmj and muscle movement while minimize the stress transfer the quizzer load should be applied at the center of denture bearing error and both anthropo serially and vulca lingually any deflections will contribute to the destruction horizontal force and magnify by leverage to the abutment and residual ratio so occlusal load applied to this third end will result into more stress transmitted to the abutment tools moving on to the surface characteristic of abutment some restoration offer more frictional resistance to the class arm movement and it contributes to greater stress than the tooth with the intake enamel when in edge class quality and design the more flexible the glass actually the less stress transmitted to the abutment however it will contribute to the less retention especially to the lateral and vertical stress that transmitted to the residual which class design is passive when seated on environment will accept less stress to the apartment so when we're talking about the flexibility actually this is really important so flexibility increase actually by lengthening the class how you want to do it so the length maybe increases by using curve then straight cos of class class material chrome alone more rigid and will exert stress on the abominant disk so motivation need to be done to the class arm by smaller diameters for a rigid material coming to the class positions in removal partial denture design there are three configuration of clubs the first one quadrilateral configuration can be seen in such cases of class 4 kennedy and class 3 modification 1.

[00:05:29]tripodal configuration you may see in case of class 1 kennedy and class 3 and lastly bilateral configuration in class 2 kennedy as seen in this photo we come to the class flexibility the principle of class flexibility basically the retention must be within the physiological tolerance of abutment tooth so rpi system being proposed rpi stands for rest on the measure possible plate and eye bar on the buckle however there is another system being proposed is rest on enemies rpa is which is rest on the measure proximal plate and echoes retentive arm why we change from rpi to rpea usually when the eye bar is contra indicated example in the case of high vocal attachment soft tissue undercut and shallow vegetable we come to this classic article by thompson at all 1977 and rebring in 2004 basically they evaluate the photoelastic stress patterns produced by various design of bilateral digital extension removal passion danger actually they look into a sick design thompson at all concludes the design of retainer with miseries and biker eye bar or a rock wire and lingual class arm these two design most favorable distribution of vertical applied force second retainer design with distal rest tend to move the ground digitally and the root measly and this is because the horizontal force in the point the third by placing rest on the pistol extension of removal partial denture more entirely provide at axis of rotation and direct apply force in a more vertical direction and number four digital rest with circumferential retainer have a greater horizontal force within a supporting structure with that with that they conclude basically rpi or rpa with the rock wire is the best design bring on to the extension base of rpd usually challenge in the extension based mucosa bearing air surface are compressible so therefore removal partial danger are replaced displaced and moved during functions so design must anticipate this movement of the removal partial denture during function to prevent overload and loss of the abutment tooth so ammon of movement is depends upon the surface area of the mucosa support area the thickness and comprehensive compressibility of the supporting mucosa the adaptation of denture base to the tissue extension base and refinement of the user factors when we look into this therefore the coverage of identification are fully extended by impression so example we may use fully extended impression with constantly or by after god's impression so we talking about all this principle we come into the conclusions of indirect retainer functions so it basically is a part of removable partial denture which assists the direct retainer in preventing the displacement of this extension denture base by functioning two level actions on the opposite side of the factory line in the retainer must be placed as far as possible from the digital extension base for a better leverage advantages so most effective location for indirect retainer is inside the region but due to their poor strength canine or primola are used when we're talking about indirect retainer basically indirect retainer changing the design of the mobile password danger into a second class level what the difference basically in class one level the mukosa of the anterior side is in pinch and there is a movement such as sticky foot when they change it to the second class level basically the indirect retainer will prevent the lesser the stress to the mucosa and the anterior gene when we're talking about rpi system basically rpi system design has a second class level so rpi which has a mesial res and alter the vacrum position is prevent the glass movement that cause harmful engagement of the environment tube however a type of retainer and guide plane on distal surface will reduced cantilever or the first glass level force eye bar is placed at the greatest curvature measured distal of the tooth if it plays at the curvature the bar will move towards forwards and tuck the tooth and loosen the tensions so others methods to reduce the stress basically a swing long danger or flexible connector that become the stress breaker moving on the final take home note when we consider a connection between denture-based and retainer we make the conclusions that more rigid connectors more stressed to their permanent teeth thus need a proper design to reproceed how why functional basing with blood coverage offset area harmonious equations and choice of direct tenor this is our references and thank you all for listening