TEACHING HUNT CONTESTANT NO 54 JAW RELATIONS Dr swetha

hello everyone i'm dr shweta from narendra dental college uh i'm here to discuss on a topic of jaw relations that is mostly a troubleshooting jaw relations mostly the mcqs so uh why i've selected this topic is that during my entrance preparation i used to have difficulty solving them secures on this topic because most of the options are nearly close and seems to be very the correct answers but mostly i used to go wrong in this particular topic so i've tried to present the solution in a simple way as possible only by knowing the definitions of certain jaw relation things okay so without much delay let's get started so what is a jaw relation it is a maxillomandibular relationship that is a spatial relationship of maxilla to the mandible it means that the mandible and maxilla is related in all the three different planes whatever irrespective of the plane it is related in all the planes and we are capturing all this uh into a relationship that is in all the three different planes we are capturing the relationship of maxilla to the mandible that is nothing but a jaw relation so we have different or three types of jaw relations that is in three manners we calculated one is the horizontal jaw relation other is the vertical and other is the orientation as you already know so the horizontal relation is the centered relation now let's get into it see uh the definition itself says many things about centric relation see ones have a look at the definition it's a maxillomander relationship that means it's a relationship in which it is independent of tooth contact since we are not considering the tooth here it is a bone to bone relation relation in the sense it's a bone to bone occlusion in a sense is the two to tooth relation okay so in which the condyles articulate in the anterosuperior position so whereas this relationship is establishing is it is a relation between the condyle to the cranium okay that is at which place in the along the slides of the posterior slopes of articular eminence okay in which position it is in the anterior superior position previously the definition used to be in the posterior most position when you look into the books of hartwell and voucher it used to be in the posterior most recruited position but since the position is found to be the strained position so or strained or unstrained but the centric relations is always proved to be the unstrained position so there is a slight change in the definition and the more revised version of the definition evolved in the gpt-9 that it is an anterior superior relationship and anterior superior positioning of the condyle with respect to the articular eminence okay and uh let's continue with the definition the mandible is restricted to purely rotary movement it means purely hinge movement usually the lower compartment of the mandible is completely related to the hinge moment which is a pure rotation moment that is possible only to a certain degree okay so 220 to 25 mm it is possible and that particular position where it is relating in in this position that is called as centric relation and this relation should be an unstrained physiologic relationship and strain in the sense all the muscles which are keeping this relationship should be in an unstrained position and also the patient can make a vertical lateral and protrusive moments that means it is the cornell is free to move in all the three different planes that is protrusive lateral as well as the vertical motion is possible and here so we have got five different terms one is where is the relationship established it is in between the condyle and the posterior slope what is the position it is a anterior superior position and how how should be the muscle it should be a physiologic as well as the unstrained uh unstrained manner they should be okay and we are able to that is the condyle is able to uh rotate freely in all the three different planes and also only the pure hinge moment is possible and there is a slight uh addition to this definition in gpth8 that does at an established vertical dimension this is very very important because i'll tell you why in the next previous slide okay at an established vertical dimension because in a vertical height is established then only one should go with the center relation because for every established vertical height there is difference in the centric relation position okay so if you calculate more that is a 3mm or 4mm beyond the vertical height you have calculated previously this intercalation changes according to the vertical height of the [Music] patient now coming to the physiologic rest position uh this is somewhat similar to the centric relation don't get confused just go through the technician it is a postural jaw relation postural in the sense it is dependent on the patient position that's why the patient patient should be positioned in an upright condition see the postural relation when the patient is resting comfortably in an upright position and the muscles are an equilibrium and tonic contraction and tonic contraction equilibrium means every muscle is fired to the same resting potential okay and the condyles are in the neutral unstrained position in the glenoid fossa that is the relationship it doesn't specify either it is anterior superior or posterior but it is compulsory that the condyles are in unstrained position it means rest it means zero so you can say the muscle should be at rest as well as the condyle should be addressed this is only taken away by the muscles and centriculation the muscles has nothing to do with it even though the muscle is guiding its center relation but uh the muscle need not be in a unstrained position but here all the muscles are in a unstrained eq sorry tonic contraction or equilibrium position okay and the condyles are in the unstrained position so this physiological responsion is dictated by the muscle rest potential so for every individual the rest potential of the muscle is fixed and it is fixed throughout the life that is why irrespective of the presence of teeth or not the physiological responsion for the individual remains same throughout the life it doesn't change unless until you will have a muscle pathology so that is why when you establish a physiological risk position in a dentate patients or ridiculous patients it reminds same almost same and it is recordable and repeatable also this is also called as the vertical dimension at rest don't get confused this is a rest position and the dimension that is established at the physiological rise position is a vertical dimension at rest usually in the vertical which is called as bdr okay vertical dimension at rest in this position usually what happens is the patient uh will have in case of i'm talking about the dentite patients usually will have uh if if the position is uh if the patient is in physiological risk position then the teeth will be slightly separated you'll find a space that is that is called as a freeway space which we'll discuss it in the later slides but never ever this in the vdr the teeth will upload because the muzzle it has to be in a unstrained position so since it is attaining the unstrained position there will be a small amount of gap in the dentite patients so that gap has to be replicated even in the complete denture also so what happens if it is not replicated we'll see in the further slides okay see here uh the picture uh it is depicting the the dotted lines indicates the when the teeth are in occlusion but the vd occlusion occlusion that is a vertical dimension and occlusion and rest is different rest there is a space that is present two to three mm which is called as a three-way freeway space okay and that position is called as a physiological rest position and the height that is established is called as vdr that is vertical dimension at rest now the vertical dimension of occlusion it is the vertical separation of the jaws when the teeth are an occlusion or maximum intercuspation you you know what is maximum intercuspation that is every cusp coincides with the corresponding rows or the forces okay so in that case if uh the vertical dimension that is established when the teeth are in occlusion is called as vertical dimension at occlusion so you we already told that in the vdr position there is slight cap so what you consider is more vdr is more than vdo so if you subtract the vdr minus vdo it gives the freeway space that is normally 2 to 3 mm okay that is called as the freeway space and there is one more point in this there is another space that is also considered which is called as freeways which is freeway space discussed here the other space is called as the silverman's closest speaking space that is around 1 to 2 mm and that space is established when the patient is at speech while pronouncing certain uh sentences you will find an active space present between the teeth that is called as silverman's closed speaking space don't get confused with the freeway space and the silverman space silverman's space is when the uh the patient is peaking and it is around 1 to 2 mm and in the space usually the muscles are active not in unstrained positions uh sorry not in tonic equilibrium that is not in resting potential they are active that means they are in contraction okay so the difference between these two spaces is one is the active one one in one the muscles are active in one the muscles are passive or press position so whenever the freeway space so now you know the difference between the two spaces so what happens if the vertical dimension is not established properly or you are if you are increasing or decreasing it how do you measure it usually you will take a distance between the tip of the nose and the chin okay that will give the vertical dimension of the patient but if it is increased ah which means you are encroaching on the freeway space you are using up the gap between the teeth uh that is supposed to be present that is that two to four mm so what happens you are firing the muscle you are not allowing the muscle to get into rest so the muscle will be in continuous firing so in order to uh overcome that obstacle uh the muscle tries to uh resolve the supporting tissue that is present so eventually it will leads to more absorption of the supporting tissues that is the mucosa as well as the moon so in that and along with that there will be some unpleasant sound in the dangers because of continuous clicking and premature contacts and there will be exaggerated facial expressions and there will also be facial distortion and difficulty in closing of the lips difficulty in swallowing so many things will happen when there is an increased vertical dimension the same is also found with decreased vertical dimension here what happens there will be over closure in the occlusion so you are not using the gap you are creating excessive freeway space more than two to four mm so there is no proper vertical height that is established so there will be over closure of the muscle so in that case the most probable the first choice is the temporomandibular joint will get affected so whenever an mcq is given the first shortest temporomandibular joint a symptom is present then you have to mark it because the over closure will only effect mostly affect the temporomandibular joint first and followed by the appearance where the chin appears to be very close to the nose and the commissure of the lips turns down and the lips usually they lost their fullness uh so because of losing of the tonicity of the muscles okay um and mostly you'll have angular gelitis at the corners of the uh mount so now what will you see you you'll have in certain mcqs there are certain terminology which will be very uh confusing so i've tried to put it up see here uh this interclassial distance versus interact space mostly will get confused okay this interclassial distance is the distance between the occlusion rims or the occluding surfaces that is the teeth indented individuals and occlusal rims in complete denture patients or the artificial teeth okay so indirectly the interclassial distance is nothing but the freeway space okay whereas the inter-art spaces the distance between the arches that is from one bridge to the another ridge irrespective of the presence of teeth or not it is an interrupt space is it clear now so next just look into the next point that is this failure to provide adequate intercrucial distance or excessive interact distance means the same failure to provide adequate interrupt crucial distance means you are not giving enough freeway space excessive interact distance means you are increasing the vertical dimension both mean the same and many of the mcqs have seen that these two are used alternatively to confuse us so don't get confused just think to the point interclusion distance is related to the freeway space interact is something related to the vertical dimension so here failure to provide that is inadequate inter occlusal distance means you are encroaching on the freeway space and you are increasing the vertical height that's it so okay next coming to the next point which is an excessive interrupt crucial distance it means interrupt crucial distance is a freeway space so you are giving excessive that means you are not uh get giving the enough vertical dimension that is you are decreasing the vdr okay video you are decreasing the vertical dimension at occlusion so both of it is dangerous but usually the book says that increasing is a bit better than the decreasing okay so now coming to orientation your relation so there are two terminologies which you have to know in orientation jaw relation one is the hinge axis so what is hinge axis it is when the mandible opens and closes the rotation occurs around the transverse axis so the rotation will takes place around an point that is called as a hinge axis the axis the plane is called as the hinge axis so the rotation we have already learned that in center relation also there will be a purely uh rotation that is happening in the uh condyle okay so if it is at the centric relation position then it is called as a terminal hinge axis okay and there is another terminology also called as transverse horizontal axis almost all means the same but to be specific if it is the rotation or the axis is calculated at or the rotation axis is calculated in the center relation portion it is called as a terminal hinge axis okay what is transverse horizontal axis it is imaginary axis around which the mandible may rotate within a sagittal plane the same thing almost equal to the hinge axis or hinge axis what we have discussed it is nothing but if you are connecting a line uh passing from one condyle to the another condyle and calculating the rotating axis of the condyle in sagittal plane that means mid sagittal is it will divide the body into right and left parts isn't it so when you are calculating this opening and closing rotating axis in that plane then it is called as a transverse horizontal axis and uh when you are calculating it you will take the mean of this and that is called as the transverse horizontal axis so so tr what is this orientation your relation means you are orienting the mandible to the cranium so you are transferring this transverse horizontal axis so that you are able to replicate the same moment in the uh in the articulator also so the device which we used for this which we use for this orientation your relation is the facebook see here you are recording this you are you are trying to record this uh thc or the hinge axis and you are trying to replicate it to the via the facebook transfer to the articulator so that the articulator will simulate this axis this kind of relationship where you will orient the maxilla to the cranium in certain angle by indirectly knowing the dha is known as the orientation jaw relationship okay see here if you're mounting this to the car at cast to the articulator the maxilla is oriented to an angle so that angulation where it is oriented you can't record it without a facebook so in order to record it we use a device called as a phase bar and this relationship in the patient is called as the orientation jaw relationship that is how angulated it is to the cranium that is maxilla how it is angulated to the cranium and how is this terminal hinge axis so the main important uh device that is used is a face pop so this is the face pump you will have different face just get into it see this flowchart the face bow if you know about the phase bur you will get to know about the orientation john relation completely so it orients the condyle maxilla relationship that is maxillary tooth condylar axis relation okay so and it transfers it to the articulator so there are different types of facebook one is the arbitrary phase buff and other is a kinematic or actual access facebook there is not much of difference arbitrary in the sense you are calculating the um hinge axis arbitrarily okay so that is why it is called as arbitrary it is not the exact hinge axis if the kinematic in the kinematic phase buff it is the exact hinge axis you are recording and transferring but in arbitrary you are taking a arbitrary axis almost near near near similarly so in order to calculate it arbitrary you should have certain land maxes in it that is why you will have the post theta reference points and the anterior reference points so this posterior reference points usually we know what we'll read as the variance point bugs from points all these are uh this posterior reference points that means they'll indic they'll indicate where this caliper has to be inserted to record the arbitrary hinge axis okay ah whereas in kinematic there is no such problem you are calculating the true hinge axis so there won't be any problem for this you will have some pantographs tracings everything so they'll record the true hinge axis in a exact manner and in this arbitrary also other than posterior reference points you should also have the anterior reference point there should be a three point standardization isn't it so in the anterior reference you will have an ac on point orbital point all these things okay so that is why in that also you will have two types fascia type and the ear bow type uh in earbud type you will get this uh ear pose which can be inserted into the external uh auditory miatas so in that case you are able to record it in that position the posterior reference is the ear points and in fascia type there will be certain points uh as i said variance points or bugs from points where you will mark it and then you will place the uh exact facebook in that particular position so here there will be ear rods in that the rods will be inserted near to that particular point so that is the difference between an arbitrary and kinematic facebook so usually in all the complete ninja cases we'll use the arbitrary uh kind of earbuds only so look into this picture this is a ear bow uh that is the posterior reference points is into the external acoustic meters that is ear rods are inserted into it and the next this is uh kinematic what we are talking is the exact kinematic location is captured here other than this there will be another condylar rods will also be there where the posterior reference point will be the condyle or the behrens point which is 13mm anterior to the outer can this line between that there you will insert the condylar rods uh same like what i have shown in the previous picture the your rods instead of that you will call there it is called as a condyle a rod here this is called as a kinematic bow where see the difference you can appreciate it in the kinematic phase bow uh this bite fork will be inserted into the mandible the clutches will be inserted to the mandible whereas in arbitrary it is positioned to the maxilla the only difference which we could make with the picture is this one the kinematic is more precise whereas this arbitrary it is not less precise okay so that is why we use it in complete danger cases arbitrary cases okay so by now you should be thorough with all the definitions it almost covers the entire topic but there are a few questions uh that are present in the topic which are very weak so after knowing all this one may get a doubt which is the first one you'll do in a jar relation first always orient the jordan orientation jaw relation is the first thing that is you have to orient the maxillar to the transverse injections of the mandible or the maxilla to the cranium either way it is correct okay after orienting or angulating at a particular position then you have to establish the vertical jaw relation that is the rest position and after that you have to go for the center relation why is that how to remember it because in centric relation it is given at an established vertical dimension that means you are supposed to do a vertical dimension before the center relation if it is not established then for every vertical dimension increase there will be change in the relationship centric relation so that is why you are supposed to do a vertical jaw relation before to the center collision so the sequence is orientation followed by vertical followed by centric so this almost covers the entire mcqs in the jaw relation topic so as we completed the topic now let's troubleshoot it so here are a few mcqs the first one is hinge axis facebook records relationship of t to the axis of rotation of the jaw so this may be a correct but see uh the correct answer is one because you are supposed to relate the maxillary teeth or maxilla to the tha or the hinge axis of the mandible that is the thing we have learnt but see the second one you may have a doubt with other two options relationship of mandible to maxilla or maxilla to mandible which is a centric relation so that can't be correct third one is relationship of mandible to cranium how can you relate a mandible directly to a cranium dha is relating mandible to the maxilla so maxilla you are relating it to the mandible so in that case the first option that is relationship of teeth that in that means a maxillary key to the axis of the rotation of the jaw is correct so uh by knowing the definitions itself you are able to solve this and so next time secure the interact distance measured when the crucial rims are in uniform contact is usually when you have an inter arch distance or interclassial distance terminology we'll usually get confused with the freeway space or something like that you'll first mark the freeway space but uh just read carefully the inter arch distance which means the distance between the two ridges as i said so two ridges in the sense it is giving the height okay so and uh look into the cue clue that is given in the question measured when the crucial terms are in contact contact means occlusion so to height at occlusion indirectly the question itself is giving the answer that is the vertical dimension of occlusion okay so the next question most accurate reproducible relationship for recording jaw relation one is physiological responsion centric occlusion center collision all of the epo so it is jaw relation never ever he has mentioned about the teeth so it can't be a occlusion so it is not centric occlusion and uh it is in between centric relation and physiologic centriculation is a point which is repeatable and reproducible and from which all the motions are carried out easily like vertical lateral protrusive so in that case it should be the answer centric relation is the answer most accurate reproducible relationship okay so next is only being pure hinge moments of the mandible occur at so uh moments nothing to relate with centric occlusion uh so first option centric calculation is rolled out second option centric relation later excursions later excursions is ruled out because in later exclusive or eccentric moments always there will be translation followed with rotation so both will be there so that is rolled out and second center relation and terminal hinge position it can be both because in centric relation also pure hinge moment is present but if it is given like only pure hinge moments of mandible the first to go with this terminal in position if it if it is given if there is no option uh telling you about uh dha or hinge axis then you should go with centric relation because that is the sequence we are following first is orientation vertical and centric the same way if the option is given like this if the question would have been a pure hinge movement of the condyle is present at a position then it is a centric relation okay so the answer is terminal hinge position next is centric relation is between a maxillar to cranium mandible to cranium mandible to condyle two to tooth so two tooth can't be the option so mandible to condyle it is in the same jar so it can't be option maxilla to the cranium uh maxilla to the cranium is orientation generation and mandible to the cranium how is this option given just look into the definition here also the basic what is given in the definition it is a condylar relationship along the posterior slopes of articular eminence articular remnants is related to the cranial part so that cranium base of the cranium so that is why he is relating the mandible to the cranium that is indirect option so you have to rule out the options like this in every possible questionnaire so here's the end of all the troubleshooting issues only a few of them are discussed here so i hope you understand understood everything and sorry one last question facebook measures relationship of maxilla 2 opening and closing access mandible zygomatic bone men so now it is very clear it is dha whenever a dha is given that is opening and closing access then it should be marked okay facebook measures relationship of maxillar to the opening and closing axis so now it's clear we have dealt with all the mcq parts only few of them have been dropped so thank you for your patience listening