RAPID REVISION SERIES PART 3 NEET MDS 2024

very very good evening okay the first important concept you can see my screen right my screen is clear right for you clear visible yes okay okay the first important concept is about the negative space okay so negative space is seen basically in the Buckle Corridor okay so normally uh whenever the patient smile okay there are two different types of smile a norm smile and exaggerated smile so whenever the patient is going for an exaggerated smile also uh there are more than 25% there are more than 25 percentage of the patients where the ging 1/3 okay the ging 1/3 is not visible when the patient is going for exaggerated smile also okay Ginger 1/3 is not visible why this Ginger one third is not visible because of different things like the activity of the lip or the length of the lip or uh uh the amount of uh your alular bone okay so there are many factors which are going to control the visibility okay particularly it is about the lip thickness of the lip or the length of the lip is going to control that okay so what is this uh what is this negative smile is basically whenever the patient Smiles okay the patient Smiles there will be a slight Gap that is present between the maxillary and mandibular teeth that slight Gap is is the negative space or you see that slight Gap where you have the dark color the dark color space is called as negative space the dark color space is negative space and apart from this the negative space can be seen Whenever there is a missing teeth Whenever there is a missing teeth okay one or whenever there is a diastema or whenever there is a fractured teeth or uh whenever a poorly restored teeth is there so in all these conditions you see this negative space this is basically the dark space okay for example in this particular diagram you can see this dark space you can see the dark space in this Buckle Corridor area right can you see this this is a dark space that is seen in the Buckle Corridor area Okay so the points to be noted is negative space is basically seen in the which area it is seen in the Buckle Corridor area it is basically the gap between the maxill and mandibular teeth when the patient is smiling it can also be seen in the case of mixed teeth missing teeth diasta factur teeth and poorly restored teeth clear clear about the negative space okay the next one is negtive uh the next important concept that I want you guys to make a notice there is something called as Dead Space so whenever you're going for a post and core there is one concept called as Dead Space dead space in post and core okay so what is this dead space in post and core can you tell me what are the different types of post you have seen in your departments in your Coles or if you're working in a clinic or if you have your own Clinic can you tell me what are the different types of posts you have seen yes one is fiber post yes most of us has seen fiber post right fiber posts right fiber posts are regularly white in color the second one what we see is metal post hope you have have seen metal Post in the department have you seen metal posts sometimes the metal post will be golden color gold coating will be there have you seen metal posts yes right so uh the concept is basically related to these two posts okay so which posts are nowadays very frequently used it is metal posts are frequently used or Fiber post are frequently used yes perfectly right the posts which are very frequently used nowadays are fiber post Can it can anyone tell me the reason why fiber post are most preferred when compared to metal post po ah okay Aesthetics okay Aesthetics that is not the main reason but Aesthetics okay AR is telling Aesthetics yes it is white in color so Aesthetics okay the main reason why you use Fiber post over metal postes fiber posts are going to have all the properties similar to that of the surrounding Dent because this is if you consider this as a post okay this is a post right this is a post and surrounding the post which is present the surrounding the post you have Dentin that is present so what is going to happen is fiber post apart from their Aesthetics Aesthetics how they help the main important property of a fiber post is fiber post is going to have all the properties particularly the coefficient of thermal expansion or when you're talking about the modulus of elasticity so modulus of elasticity cient of thermal expansion and all the properties of fiber post are similar to that of the Dentin so whenever there is a change in temperature in the oral cavity how the Dentin is reacting fiber post also react in the same way how the Dentin is expanding fiber post also react in the same way for example there is a stress how the Dentin is Distributing the stress fiber post reacts in the same way transferring the stress to that of the den you got it right you got the reason why fiber Bast are more preferred when compared to that of the metal post right clear yeah so that is the reason why we always prefer to have a fiber post okay so what is the problem with the metal post you see here in this diagram you have a metal post okay so what is the problem is metal post metal is going to have most more coefficient of thermal expansion than the Dentin so what is going to happen metal is going to expand more when there is a change in temperature when compared with the Dentin and it is going to cause more stress on the surrounding Dentin that may lead to the fracture do you accept this metal is having more coefficient of thermal expansion so whenever you heat it metal expands more and Dentin expands less and this is going to create stress and this stress may lead to the facture in the future okay so that is the reason why whenever you're looting whenever you're looting metal posts metal post looting okay whenever you're looting the metal post you have to leave some space allowing leave some space because this space is going to compensate the expansion of the metal so you have to allow some space okay so that the metal can expand in the space that space is called as Dead Space so that space is called as Dead Space what is dead space in the post and core to you are going to allow some space for the metal to expand in the post and core system that space that extra space whatever you're leaving is called as dead space clear right clear guys okay now tell me okay now tell me okay the concept of dead space in post and core is for option a metal post op option b fiber post option C both what is your answer okay right so right right correct so dead space concept is only for the metal post you're not going to leave any sort of Dead Space whenever you're going for the fiber post clear and what is the advantage of fiber post over the metal post is fiber post is going to have all the properties like for example a coefficient of thermal expansion or you're talking about the modulus of elocity all the properties are similar to that of the surrounding Dentin so how a fiber post is going to expand is almost same as the surrounding Dentin okay clear done okay done so then there is one more concept that most of us are familiar that is called as dead space in respiratory system physiology what is dead space in respirator system what is dead space in respirator system so dead space in your respirator system is a place where gases exchange does not takes place okay where gases Exchange does not takes place that space is called as dead space no gas exchange the space is called as Dead Space so dead space in your respiratory system is basically of two types what is that anatomical dead space and physiological Dead Space okay anatomical Dead Space is related to the anatomy whereas physiological Dead Space is anatomical Dead Space plus area where area where gases exchange takes place previously but now there is no gas exchange that can be due to a or that can be due to uses of some some products or something previously it is an area where gas exchange takes place but now it is not gas ex does not takes place clear so anatomical Dead Space is anatomy related physiological Dead Space is anatomical Dead Space plus areas where gases exchange does not takes place clear done okay now yeah so areas anatomical de space is basically the upper volume of the the the inner volume the inner volume of the upper air waste that is basically the nose fings trachea and broni and these are the areas where gas excess does not takes place so there are those areas are called as anatomical Dead Space whereas physiological Dead Space is anatomical Dead Space plus areas which are previously gases exchanged but now they are not able to exchange the gases so that is called as physiological Dead Space can you tell me what is the normal Dead Space value in respiratory system normal dead space in respiratory system yes the normal uh dead space in the respiratory system is going to be 150 ml is going to be 150 ml very good it's 150 ml okay so now you have a case in front of you so can you tell me what is the Elise classification of this particular case uh you can see a discolored teeth what I can see is you can see a crack I can see a crack one is I can see a crack and I can see a discoloration so discoloration is going to give me a hint that the the theology can be uh the necrotic the necrotic pulp so whenever you have Elise classification leading to the uh leading to the necrotic pulp okay uh nonvital teeth the answer is Ellis class four right so tell me what is the treatment plan for this interns post interns clinicians what do you what do you do what do you do if such case is came to your clinic yes first of all we are going to do because it's a necrotic teeth okay we are going to do a normal root canal therapy normal RC we are going to do is followed by by why you go why you go why you want to go for a post and core Crown is where nice Crown is there no need of post and core okay so followed by you are going to do non vital bleaching for this case Okay so once you're done with RC so what you're going to do is you're going to remove the gabacha 2 MIM below the ging Regis or below the marginal Ginga okay then you are going to keep uh a barrier so regularly what barriers are used you're going to keep a barrier so that the bleaching agent will not go to the root canal system so what barrier regularly we are going to use in the nonvital bleaching so what barrier we regularly use in the nonvital bleaching is GIC GIC or modified GIC and what is the material of choice for non vital bleaching nonvital bleaching is basically done by yes nonvital bleaching is basically done by a combination of sodium perborate plus hydrogen peroxide as an activator okay sodi sodium perorate plus hydrogen peroxide is basically used for nonvital baching Clear guys done can I move I hope you're clear with this diagnosis of this case is you can see a crack and a discoloration that is basically due to the necrotic pulp and the class and and the diagnosis is going to be at least class 4 or if they're asking uh your like American Association of Endodontics classification this is going to be an ecrotic pulp basing upon the radiographic features or clinical features you have to diagnose the periapical area for example if the patient is having tendron vertical percussion for this case so the diagnosis is going to be necrotic teeth with symptomatic epical peridontitis radiographically epical changes are there but symptomatically the patient is not having any sort of symptoms then it is going to be necrotic teeth with asymptomatic epical parodontitis okay so now what is the treatment is you do an RC keep a barrier that is a GIC or resin modified GS you're going to keep it as a barrier so once you're done with that you're going to do nonvital bleaching with sodium perborate and hydrogen peroxide in combination okay right clear so next is uh we we'll have some important points so this is basically uh metal ceramic okay so you see metal ceramic uh crowns okay now tell me what is the finish line of choice in metal ceramic Crown metal ceramic Crown Finish Line of choice yes metal ceramic Crown has two Finish Lines one on the labal or facial side second on the lingual side the better option for the labial side is going to be shoulder with bevel shoulder with bevel is the best option if you don't have that you can go with shoulder as an answer and on the lingual side the answer should be shamer clear right clear so it has two parts of Finish Lines laally it is going to be shoulder with bevel and lingually it is going to be shamer next we'll try to understand few other important points uh that you have to make a note okay right so one of the major reason for acceptance of porcelain fuse to metal is basically because of its greater strength and resistance to facture the combination the the combination of porcelain to that of the metal fused together is stronger than the porcelain alone because porcelain is weak here it is stronger and whenever there is a failure that is being happening okay the bond between the porcelain and metal is so strong so the failure mostly occur in porcelin only rather than the porcelin metal interface okay so those are the important points next one when you're talking about this porcelain Fus to metal the metal substrate substructure should be 05 means the thickness of the metal should at least 0.5 very frequently Asked question the minimum thickness of the porcelin should range from 1 to 1.5 mm so what is going to happen the total reduction is metal plus porcelin that is 0.5 .5 plus 1 to 1.5 which is total is equal to 1.5 to 2 mm which is ideally 1.5 mm thickness is required the most frequent cause of paracity in the porcelain is basically due to inadequate condensation of the porcelain and that is basically due to the shape and size of the particles that are used all these are mcqs okay all these are mcqs right here I want you to make one more important point when you're talking about the coefficient of thermal expansion values that is Alpha values of metal and Porcelain metal should slightly have more value when compared to that of the porcelain and as you know porcelain is much stronger under compressive forces when compared to the T Cell forces so porcelains in all ceramic registration should be avoided by keeping okay by keeping the preparations rounded by keeping the preparations rounded first important is metal ceramic Crown labial side shoulder with bevel lingual side shamer factures can most commonly occur in porcelain rather than porcelain metal interface thicknesses of metal is going to be 0.5 porcelain thickness is going to be 1 to 1.5 total thickness is going to be 1.5 to 2 mm compressive strengths are more when compared to tensil strengths in the porcelin so in order to prevent facture in the case of all ceramic registrations it is better you round off all the angles the alpha value of metal is slightly more than the porcelain clear done I'm going to the next concept so next concept slightly concepts related to smile designing okay so can can I know what is the percentage value that you have to make a note when I'm talking about Golden proportion so what is the value of of golden proportion exact value of golden proportion yes the exact value of golden proportion is 61.8% is 61.8% is so please do make a make a note about the scientist name also so golden proportion is basically telling you that comparison of miso distal dimension of lateral to Central or Central to lateral or lateral to Canine or canine to lateral that is visual that is that you view from the frontal area so this is basically the apparent miso distal Dimension not the exact Dimension right you got it right this is not true Dimension it is apparent Dimension what is visible from the facial surface so what is this telling what is the 61.8 when you compare the Miso distal dimension of central incisor to the Miso distal dimension of the of the lateral incisor okay means for example your central is 100 percentage your lateral will be 61.8 perent if your lateral is 100% your canine is 61.8% I'm repeating again this is not the exact misal Dimension this is an apparent Dimension what you see from the frontal area so so what is visible because Canon is slightly curved so entire Canon will not be seen so whatever you see that will be 68 percentage of the dimension of the lateral what you see lateral that is 61.8% of the central incor got it right you got it right if they're asking in the ratios your answer should be 0.618 0.618 or 61.8% okay so I'm done with the golden proportion the main disadvantage of a golden proportion is golden proportion is talking about the apparent Dimension not the original Dimension that is the biggest uh that's the biggest disadvantage of the golden proportion now you have one more proportion what is that red proportion red proportion is nothing but recurring Aesthetic Dental proportion which is given by what so what is this basically okay so lateral by lateral by Central is equal to Canine by lateral canine by lateral got it right so 2 by 1 is constant value that is equal to 3x2 is a constant value so that is called as red proportion there's something called as M proportion which is very very frequently given in these examinations M proportion is telling the width by length the width by length ratio of a particular teeth should be 4X 5 they're asking in percentages you need to go for an answer around like 75 to 80 percentage done if you're done please do respond me