so everything is interconnected and all of us are aware of it because when we are in the clinics we are using so many different concepts altogether and it also applies a lot to biomechanics biomechanics being the bedrock of doing braces it borrows a lot of concepts from so many different aspects so as an example here you have some of the concepts this is not an exhaustive list of all the biomechanical concepts but these are heavily used in day to day of orthodontics even though many of us including me we don't realize at that point that we are using these concepts but yes we are and purely from a clinical efficiency perspective you'll get better and better the deeper you dive into those concepts which will look which will appear pretty huge and it will appear like an onerous task to master them but and I'm in that process myself but the more you understand them the more you find ways of adopting or inculcating them in your clinical practice as you guys go out to do orthodontics you will get just better and better in terms of efficiency in terms of how much amount of time you're spending on the chair with a patient in terms of diagnosis and treatment planning so these are important I call them as the first principles of biomechanics first principle basically means that these cannot be changed no matter you like it you don't like it these apply these are happening these are taking place in your patient's mouth of course we can do braces completely ignoring them but what I believe is that when we do that we are stuck in this situation where we don't see a lot of improvement in our clinical efficiency as years go by I'm not saying you won't improve absolutely in terms of clinical efficiency because other aspects like practice management what stuff you're buying all that will kickin and you'll get better but as far as using stuff in the patient's mouth and how to move it better better and in a more efficient manner these first principles are immutable they have they they they they are happening all the time and if you make them your friend it would be pretty pretty helpful in increasing your output so just to give you an idea as to what we really touched upon in biomechanics one we basically just discussed these two aspects and well they are kind of the foundation of all these first principles also but they are just as you can see a small part of doing braces unfortunately from my experience at least what I've seen going to different universities to different countries that 95% of the places we are basically relegating ourselves to just these concepts in terms of teaching biomechanics or using biomechanics I have yet to come across courses or academic schools or you know see courses that go deeper into these other aspects or at least touch upon them in a way that it is useful clinically so this is just to give you an idea about what we deal with in biomechanics - out here so what I'll do is I'll just touch down upon what we discuss in bio one as I said please feel free to jump in and ask if any there there anything any aspects you're not understanding okay so force and moment what is a force and a moment a force is a vector quantity and it has got these following four of course we know it's the act of pushing or pulling an object so it has got a magnitude attached to it which is denoted by the length of the arrow that you draw a force will always act at a particular point so it has got a point or force application it has got a line of action which is dictated by the way you are attaching your chain or coil spring or whatever you use so this is the line right so this is the line of force action and then of course it will always have a direction up down back forward or if you're measuring in terms of angles that I'm applying the Steep force I'm applying a flat force so these are the four properties of force now what a force by itself it does it will always make an object move in a straight line so when you apply a force to an object it should technically I'm imagining now that only a force exists it will make it go in a straight line now we know that forces act at not necessarily I what I mean to say the force not necessarily acts at the center of mass of an object so as soon as as soon as you see a force not acting at the center of mass of an object another vector quantity gets introduced call a moment so a moment will cause an object to rotate around its center of resistance so force is causing it to go in a straight line the moment causes it to spin around its center of resistance the quantity the quantitative aspect of moment is given by force times the perpendicular distance not the distance from where you are putting the force to the center of resistance so it's not in this fashion you don't measure force like this that would be wrong in terms of the disk that you want to counter you're trying to so evaluate you have to go like this so when you combine a force and a moment together you get the final movement of your teeth and that's why when you apply a force like this on a tooth the force is causing it to translate the moment this is causing it to rotate and if you combine them the tooth will spin somewhere around this maybe I'm drawing it slightly apical somewhere around this part okay make me let me make a more accurate there okay so it's a it's the center of rotation that is created which is generally one to two millimeters apical to the center of resistance for an incisor this is well researched well documented alright so there you go that's the how a tooth will spin when you have both the force which is creating a moment is acting on a tooth so there are some ways of creating different kinds of tooth movement and broadly speaking there are two basic pathways only the first pathway is if you can change the point of force application then you can create different kinds of tooth movement and the second is the moment due to force that you saw in the previous slide if that can be altered so this moment you to force can be counteracted by a different moment then you can create a different kind of tooth movement so these are the two different ways by which you can create different types of tooth movement and of course there are certain concepts associated with it we will not go deep into that today as as we are just doing a quick recap but important concepts to keep in mind is are starting from in order of priority equilibrium key and then the M F ratios or better the MF PI moment due to couple ratios these are important equivalency is something that is it is important to know but I would place these two concepts above equivalency so looking at the first way of changing the tooth movement by that is by altering the point off that is by altering the point of force application these are consecutive pictures that kind of shows you how by changing the force levels you can create different types of tooth movement so there's a force at the bracket you get this characteristic uncontrolled tipping this is the definition of uncontrolled tipping that is when you apply a force right at the bracket and you have no other force applied to it or any kind of resistance being applied to it in any way then you create uncontrolled tipping so the center of rotation is one to two millimeters apical to the center resistance if you move the force level up by using a power hook or power arm as you commonly see attached to some of the brackets or you can crimp it to your wire you create a situation where you reduce this moment due to force and because it gets reduced the translatory effect shows its prominence and you get a center of rotation which is apical to where it was before in a classical situation if it said right at the apex you get control tipping as you are aware of and going following the same pattern you keep on moving up at some point you will go be very close to the center of resistance and then as we know we are going to translate teeth at that point and if you keep on going further up apply the same system you will start creating a moment due to force now in the opposite direction as compared to these two of because you are now above the center of resistance not a very convenient way of torquing the roots but if you have an option can be utilized to thwart roots all right so the second method of altering tooth movement is by applying a counter moment a counter moment is basically a moment that is applied in the opposite direction of this blue moment that you are seeing and that is what you see in the literature being measured as moment due to couple by force these are just some of the ways by which you can apply a couple as we are aware of when a wire and a bracket in track together in this manner any of the manner you create a moment you to couple so of what pure rotation EMF ratio is infinity because when you are purely rotating a tooth you only have a moment you don't have any force right for pure rotation for uncontrolled tipping it is zero by one why because you only have a force in an uncontrolled tipping you do not have a moment you do couple to control that for control tipping it is set around seven is to one which basically means you are exerting now a substantial amount of red moment for translation as someone answered yes it is close to 10 is to 1 and then of course logically it means for root it goes higher up now the problem with this ratios is that suppose I give you some measurements like it throws some numbers suppose the force is 100 grams I hope all of you can see what I'm drawing I mean just assuming you can and this distance is 10 millimeters can we tell me the MF ratio required for translation you are 100 gram of force 10 millimeter was the distance that is this distance so you calculated how the in size that is dumping its dumping with a moment of thousand gram millimeter right so you have to basically just counteract this by this red moment here so you know that the counter moment you'll be creating would be thousand and then you say okay I need to calculate this ratio out here so I'll just divided by the amount of force that I am creating and that becomes 10 is to 1 is the the answer that is awesome that's correct so let's remember this value and now suppose I change it up a bit I say that you're applying a force of still so let's just change this variable so it's 100 grams and this is not an incisor or say it's a canine and this distance is 13 millimeters what's your MF ratio now for translation that is you take the force and you say okay let me calculate that is dumping moment which is 100 into 13 right this is 13 so that gives me a force of a moment of 1,300 gram millimeter of dumping moment I'm getting that means if I counteract the dumping moment by the same amount of up writing moment or moment due to couple I'll create translation because I get rid of all moments so 1,300 would be that up writing moment this one and I divided by the amount of force I'm using 100 now I get a ratio of 13 is to 1 all right so previous example I got 10 is to 1 and this example I got 13 is to 1 that shows you the importance of why measuring things quantitatively in M F ratios is a bad thing it's it's the wrong thing that we have created in orthodontics by putting all these values to it because as you can see what defines this M F ratio is basically what's the distance of the center of resistance to the line of force so if you got a molar can you make a guess as to what would be the M F ratio for translation the center resistance is about 7 to 8 millimeters from where you would probably place a bracket so the up writing the moment to force ratio becomes 8 is 2 1 okay if you have a canine it's usually about 13 millimeters to 14 millimeters from where you would put a bracket so it's 13 is to one for an upper incisor central incisor it is about 10 millimeters so you see all these teeth have different MF ratios in terms of altering their tooth movement there's no simple rule there's no simple recipe that that will guide every tooth for different types of tooth movement it's all varies and then you can imagine that an add nickel variation in every tooth a central incisor can be long or short for that matter so the MF ratio will vary so it's not a great idea to stick to like quantities but it's it's important to remember that yes if I want to translate I require a high I'm afraid sure that's a decent assumption if I want to do control tipping I don't think I'll need a very high moment to force ratio as compared to translation and of course if you want to do route working does it just moving the route back and keeping the crown where it is then you require even higher MF ratio but putting a number to it makes it you know it just it just defeats the purpose of having these ratios because then you can easily prove that they are wrong so that is something that I wanted to just clear up this is just something to remember in order to distinguish MF ratios and the to distinguish moment due to force and moment you to couple a moment you to force is dependent upon the force of course that you are applying and its distance from the center resistance so it depends on the morphology of the body like if you are applying a force is it very close to the center resistance is it really for the further away for example if you have a if you have a canine that is very upright and you are planning on retracting it great you apply a force here the center resistance what if the canine was kind of having a tip a huge tip like this and you're applying a force like this okay so in which picture do you think you will get more moment do to force a or B just happen that here it is tipped so this distance is very less because remember is the perpendicular distance while here it is much more so this is a very obvious variation that I'm showing but our claim in our clinics in our patients all these kind of subtle variations happen all the time some patients you get a lot of dumping when you are retracting the incisors in some patients you don't get a lot of dumping although you follow the same protocol like I'm sure some of you do certain kind of wire certain kind of chain for incisor attraction all the time almost in 90% of the situations but these kind of variations can introduce a lot of different outcomes of the same mechanism that you're using for space closure or moving teeth so something to remember a moment you to couple is not dependent on this kind of issues that is how much is the distance to the center resistance because it is basically created most of the times by two opposing forces that are equidistant from each other and are off hopefully the same magnitude so say for example just imagine this to be a lower molar that is tipped right and you have to upright it and you put a bracket here and you create an up righting moment and a priding moment can be created by putting a force here and by putting a force here right so when you do that can you tell me around what point will the molar rotate so here and of course we are assuming that you're creating this two forces by whichever way you are but for this system let's assume that only these two forces exist so if only these two forces exist they classically are a couple force to equal and opposite so when you create a couple you are creating a moment due to couple a moment you to couple as the definition of couple goes will always act around the center resistance right here so the tooth will spin around this point it can spin around this point if you have all continuous wire that means you are creating different kind of force system any other continuous wire in terms of friction and everything or you are chaining or doing something else that is you are not purely creating this couple if you are purely creating a couple it will spin around this point so that means the root will go here and the crown will go here of course if you can create a center rotation here then you are achieving a pure torque that is the crown also rotates but very less but the root locates a lot right if you create a center of rotation right here the beautiful thing about momentito couple is that now imagine this patient was you know having this as impacted tooth and the oral surgeon exposed just this much part of the tooth and everything else is buried inside now you can still put the tube here create the same force system and you will get a center of rotation exactly here so it doesn't matter where you put the tube here here here here anywhere you will get the same kind of truth movement that is around the center resistance so this principle itself helps you in some of your patients when they're going to periodontics or oral surgery to get exposed they don't have expose the central part or you know or a lot of the tooth you can just ask for them exposing this much or in your practice if you are doing laser dentistry you can use a laser to expose this much part and just put a tube and create a couple right here and it will beautifully upright in a way that it spins around this point dr. Mattern yes you know I have a question so how exactly we will be able to do like a such a force only a couple on of two corners of the tube instead of putting like extrusive or more intrusive like that physically speaking correct that's a good question so for those in terms of if you want to purely create this kind of force system you use something called as a one couple force systems and I'll be giving showing you a lot of example at least a few examples of these one couple force system so there are one couple force systems can be I'm sure some of you might have used for example in up riding spring so imagine there's this a molar with a tipped bracket attached to it so this the molar is you know as I've shown before tipped now if you have this wire a little hook at the end of it you take this you insert it so it will be like that and I'm imagining the rest of the teeth have an arch wire going through it but this arch wire is not engaged in this tube you just take this and move it up and you hook it here so in this way you can create a very pure couple system here so it's just a simple design takes I don't know like 20 seconds chair time of making it so this will create an intrusive force here but this would be completely negated by all these teeth that you have included with a win big continuous wire and I'll show you clinical pictures and here you will get two forces like that one of the forces this one will be slightly more than this one that will create sorry this force will be slightly more the upward force than this one so you'll get a net extrusive movement but you'll also get a heavy couple to up right this tooth and that brings us to from your question that you asked was a very timely question because now we can easily go into differential moments differential moments is a concept where you create different moments that is as you know as you had asked a question right now where you said that how can I create a moment on that molar that we were talking about so in your treatment you're looking at the patient and you are saying you know what I just want a moment on this molar and nothing anywhere else that is what differential moments answers it gives you the capacity to create a moment at one tooth without creating any kind of moment or any significant moment at the other tooth that is different moments are created at different feeds you have the power to create same moment at two different sites different moments one very big moment one very small moment one zero moment one a lot of moment so you can alter the way you want to alter so this is that example what I was trying to show a one couple force system it has a simple method of action where imagine this to be an impacted canine right just imagine that and there's a bracket on to it I take a wire I put it in the molar tube and I basically I mean of course when I put in the molar tube it is lying flat like this but I stretch it I kind of pull it up and I engage it here but I am tying it to the bracket I'm not inserting the wire inside the bracket right the wire is only inserted inside the bracket on this tube that is why it is known as one couple for system because the wire will create a couple only at this bracket okay and what I mean by again by couple is that when the wire is inserted in the tube is gonna lie somewhat like this that's how the wire is lying so it is touching the tube here and it is touching the tube here that creates this huge moment while here there is no two point contact like there is no wire going like this so there is no couple created it is just tied here so when it is tied it just creates a single force as shown so so this is how a one couple for system work it's one of the most predictable force system that you can create so if this is a 20 gram force you are creating can you tell me what will be the force here 20 grams okay because of not because of Newton's third law every action has got an equal and opposite reaction but because of the principles of equilibrium that in infinite system you are creating X force here then somewhere in the system X force will be created in the opposite direction because the system is in equilibrium okay so this is 20 gram and based on these two forces you can calculate how much is this moment being created okay if I give you this distance that is the distance between these two is say 20 millimeters I'm sticking with 20s maybe let's make it 30 okay so that we don't get confused with numbers here so imagine this is 30 can you tell me what is the moment you took couple created at the molar tube will be 600 gram millimeter so what you do is again you use the principle of equilibrium which says that the sum of moments created in the system so MA MB will be equal to 0 it has to be so you know there is a moment being created here which is the moment at the molar tube so ma is moment at the molar tube plus the other moment that is being created is only being created by these two forces right because these are equal and opposite so overall they are creating this huge moment for the whole system to spin in a way right and this I know I can calculate this moment this huge one which will be this force times of course this distance because that's that's how you calculate the moment due to couple so force times this distance gives me 600 so 600 is so moment at the molar tube and again I'm talking here moment you to couples not moment you to force so moment at the molar tube moment overall is zero so moment at the molar tube comes to be minus 600 and that minus is important because it tells you that this moment is opposite to of this because this is a positive this is a negative and as you see this will be opposite to this guy to this one that we draw so clinically it's very easy to calculate is calculator I'm not saying you have to clinically what's more important is to know the direction of this moment so that when you are moving a canine like this you know what are the side effects being generated on the molar tube so the molar tube is feeling an extrusion again due to the law of equilibrium it's also experiencing a forward moment if you want to call it that way that is this whole molar will tend to tip forward as we go along and if some of you have done can an extrusion with these Springs without a TPA or something you will see that happen very quickly this forward movement all these moments that we discussed were moment due to couples if you're wondering where is moment you do force that is when you introduce those teeth structures then you start getting moment due to force okay so because this force line of action if I assume is like this so it's this much away from the center resistance I get this moment you do force this moment you to force has nothing to do with equilibrium or balancing your forces or anything of that sort okay so this is what it is this k9 could have been absolutely straight if it was absolutely straight I won't get any moment you to force so it just depends on the inherent anatomy of the tooth as I told you before similarly here if your tube was not in the correct position it was slightly off and this is a center of resistance you might create a little moment you to force but for most purposes it's like insignificant because normally we are dead on with this or even if you are slightly off it's no big deal so the blue ones are moment you to force the red ones are moment you to couple all your or your laws of equilibrium are for these red things not for the blue things so that's very important not to mix up these things when you're thinking about what is the force system being created you can use it for can an extrusion as we saw molar up writing we did that too for torquing you can use it for torquing interestingly there was a article in a Jo do in GN very or February this year there was a clinical study where they'd used a one couple torquing system to torque lower incisors they did like 20 patients or 15 patients so that was interesting they used exactly a one couple for system to create a torque and then as someone said intrusion arches you reverse it you get an extrusion or these are beautiful examples of one couple for system you can use the same systems to fix canted occlusal planes I think this is really effective like if you use these to fix canted occlusal planes it works super fast and then there are some ways of using it with sliding mechanics to for space closure all right now if you take your wire and your bracket just tying it you insert it at both the ends then you create a two couple for system right because now you have your your wire inserted at this bracket as well as this bracket so here you'll get a couple and here of course we know we'll get a couple so it's called as a two couple for system and of course if the force is down here the force would be up here all right now if suppose I move this Bend here what will be the direction of the force here up or down if you said yeah if you'll go up yes that's the correct answer it will go up right now if you put a pinned here like that you have to figure out other things too right for example what is the directional moment here and what is the direction of moment here and then if I change my Bend from here to here then what is the direction of the moment at both the brackets so what I'm trying to show here is that as as soon as you create a two couple system so you have just increased you have basically moved your appliance design complexity is slightly up and you see that things gets pretty complicated in terms of predicting what's gonna happen right so that's why as soon as you go to to bracket systems like this these are known as statically indeterminate force systems in the sense you can make some educated guesses but as soon as you start dealing with all these intricacies of moving the bend from here to here and then trying to figure out what is the moment created here and here it gets a bit complicated it's not that easy so people in the past have done a lot of experiments by taking two brackets like this and saying okay let's do this thing let's put first a bend right in the middle right here and see what happens so they found out certain things then they said okay move the brained here and see what happens and then they said let's put the bend here and see what happens so on and so forth what they found was the intensity of the bend that is the amount of degrees of bending they are doing does not matter what is critical is where you are positioning the bend are you positioning the bend here or here or here that is critical okay of course if you position a bend here these two would be same in a way it's just that the four systems will reverse so where you are positioning the bend from the middle opt into bracket distance to how close you want to get to this guy the fourth system will change and this is what they found and we had discussed this at length in biomechanics one but here I've just have a quick summary and this is what is the universe of putting a step Bend so these two pictures are four step bends and the rest are for V bends and if you look at V bends this first picture this V bend is assumed to be put very close to this bracket so when you put a V Bend very close to this bracket you get a huge moment here okay and because you get a huge moment here the counter balancing moment would be in the opposite direction following the laws of equilibrium and this counter balancing moment results in this exclusive and intrusive force alright now when the bend is moved forward so instead of putting a bend here in this picture you are moving it slightly forward so that it is about one-third of the total distance then you still get a good moment here but here you get very less moment on no moment okay and when you place a band I'm coming to this extreme picture now right in the middle right here you get equal and opposite moment when you get equal and opposite moment at both the ends that means if I add them up my net moment is zero all right so there is zero net moment there'll be no vertical forces so there are no vertical forces produce when you place a bend exactly between two brackets so these are just some of the interpretations that you get by playing around with two brackets and a bend in between all right these are known as V bends I'm leaving these two out for now I'm just saying all this these are known as V bends and people use it in many different ways to do different kinds of tooth movement examples where you can use VPN so V Binns are used as anchor pens I would also record this as very important and as you said that for doing any kind of TPM mechanics I don't know if you guys are doing it for torquing or for distillation you have to have a very good concept of how we bins work so this is huge something called as cable bends our offset bends that you might be using also uses a V Binns so they're basically two V bends placed like this sometimes as a gable band or when you are trying to upright teeth then you're using again 2v bends so that's one way and that's another way so for tipped teeth you're using that these are all cable bins essentially why it is useful to learn the first principles that is the one couple and two couple four systems is you don't have to individually understand how each of these things work if you know your first principles you can just straight away apply them and you will know how these are working in fact you can create your own methods or your own appliances based on these principles of V Binns so these ground rules are very critical loop mechanics entirely works on the web in principle completely so that is there and then torquing systems work with that that age rodeo article that I was talking about that came out in January has used this mechanism of torquing teeth and you can also create intrusion and extrusion which we bins are very popular appliance that uses it is I don't know if you guys use it is called a utility arch there so this uses a V band you put a band either here or here or here wherever it's all working on V Binns principle it all goes back to understanding this particular slide and if you know this how this is going as you move the bend you can define any kind of device or appliance that you're using and if I ask you to follow this particular moment here you know so when you put a bend here this moment is going in this direction but when you come to this picture it vanishes as I as the bend as we move further forward and then you come to this picture the bend is move further forward and the moment reappears here but you look at the direction between the two here and here they're in the opposite direction so the questions are like what is actually going on like when we move these bends how do these moments appear and reappear so that's a good question to ask the other questions to ask is what happens if I increase the bends which I kind of touched upon before and this two bends are kind of mimicking like a premolar molar bracket or a molar canine bracket but what happens if I have a molar bracket and I have an incisor bracket you know then how do these bends behave so these are some of the questions that are important to understand because if you understand them it helps you understand actually you're applying system that is your brackets so if you look at this picture this shows how you know two brackets would be would appear to you like if you have a clinical patience you want to view two brackets sitting next to each other this is how they will appear right but actually what is important for you is just the slots everything else is noise and this slot dimensions are good to know because it helps to understand what you are dealing with it can be anywhere from three to four point five millimeters depending on you know what you are looking at molar tube or canine bracket or incisor bracket and this thing that we are dealing with is the height of a slot which is 0.022 if you are using a twenty to twenty eight and we cannot see the depth here which is twenty eight so what I want to emphasize is that the ratio of the length of a bracket to its height is pretty amazing it's about five is to 1 because 0.022 basically translate to about 0.55 millimeters so this point so if you do the ratio between so our brackets are actually very thin we imagine it to be like squarish but actually they are very thin and this is important to know because this creates a lot of interesting things when you put our bend in or in a bracket so I imagine this to be seven millimeters and as I said this is Oh to two inch so when you put a wire right in the middle of the two brackets you see how the black wire is touching the corners of the bracket right here and here so this is what creates two an equal and opposite moments right now when you move a bend here slightly off to one of the brackets and if this is 1/3 the distance what is happening here this is interesting to note what is happening on the other side is that the wire is only touching one part of the bracket not touching this part so what happens is even if you put a V bin it doesn't matter how much degrees you put here it's not creating a moment it is just creating a pure force okay so however on the other side yes you get a very strong moment all right now I can keep on going this way and move the band even further towards that bracket so when I do that then I put a band here something interesting happens here the wire because of its flexibility recurves right and then it recurves it starts creating this moment it is not that big I've just drawn it big but this is the much bigger moment but here also you start getting this little moment okay so when you put a band super close to one bracket this bracket will have a huge moment but then you might get some moment even here too okay so this is interesting to note now things change a bit if I replace this bracket with a in size a bracket this is how it will look if I do that so instead of this bracket I have this alright and if I draw it to exact scale that is how they will look like if I take a clinical picture and try to represent it on a slide that is how they will actually look so now then you have a bend that is placed like this there is a complete set of different interactions happening here because now this is not in the so-called second order like the bracket is not like this it is just this right so what was previously your length on an incisor it becomes your depth so this changes your geometry is a lot and this is what I mean by that so let me clear this off yeah so what we were previously doing was that we had these two slots like that now if I place a v-band between these two we know that it's going to create equal and opposite moment but if I replace it with an incisor bracket like that as you can see here it is not in a position to create a couple there's no way a couple being produced here because for a couple to produce this and this have to touch and it's not touching here okay and this can be seen in a little picture here which we because we run a lot of these experiments this is how the bracket and wire look if a band is placed here right it is just sitting on the roof so there's just a single force that this wire is producing even though if you had to if you had a molar and a canine bracket it would produce a couple this same we been it will produce a couple here but here it does not and this is an important point from a clinical application perspective so what do you need to do it's a question what you need to do to create a couple here what could you do if I transition from here and I place take the bend forward there like that now you start getting this contact here and here so the moral of the story is that if you put a bend closer to the incisor that is only when you start getting some kind of torque here okay and there a whole reason why we are to go so much close to the incisor is because the second order arrangement gets you easy torque but when you are dealing with incisor brackets which are relatively bigger this dimension and shorter this dimension you'll have two angulate the wire a lot to get the same couple right so there's a lot of difference between the two so the bends have to be moved much closer to the incisor bracket to get a good torque so that is key and that straightaway ties into some of the wires that we get so when you put a curve of speed wire and if you are putting it with the assumption that this curve in the front here will create a a flaring effect or a twerking effect you know that will cause some flaring it won't do that because if you look at this and if I join the two ends of the wire a Bend is occurring here while my incisor bracket is here actually I have to make sure that this is moved somewhere here and the only way you can do that is by modifying your curve of speed wires that is if you flatten out the ends now you look at this now you have moved your bend previously from here to here so just by suppose you're dealing with a clinical patient a div - and you want this rapid flaring of your front teeth a good idea would be to just flatten out your curves P wires at the posterior end a little trick can get you that flaring much quicker and much faster as opposed to just kind of you know blindly going with the customs with up with a set wire customizing it really helps so that is one example of that now of course if we move this Bend closer to the molar the front teeth don't feel anything in terms of a couple at all so this configuration is a safe bet if you want to create as somebody was saying somebody correctly answered when they said that we use a V band to create a to reinforce Anchorage so this can be a good way of creating a lot of moment here but hardly any moment here so that you can let this incisor go as you please in terms if you want tipping it will still undergo a considerable amount of tipping so this location of V band becomes very very critical all right some of the questions that we always had when we as we dug deeper into these things were that which type of wire should we use how much bends took place and so on and so forth and we ran a series of experiments in which we simulated a molar and an incisor bracket and we put a lot of bends with different wires at different positions to see what kind of force and moments are we getting so we kept on shifting our bends from this position to this to this to this and we tried different angles we went 15 degrees even 20 degrees we've been thirty degrees and we had different sizes of wires right from 21 25 to 1622 and we just wanted to see what what is what is going on actually so these are just different positions of bends that we try now this is not putting all the bends are at once like one wire we put a bend here one wire we put a bend here one wire we put a bend here so different wires are different bends but we just tried every possible position to see what what we are getting and well we got a lot of stuff we got a lot of graphs I won't go you know very deep into these graphs I just come to the point so this is like a summary graph of everything so you can imagine we tested like four different sizes of wires then we tested two or three different varieties of wires then we tested three or four different angulations right from 10 12 15 30 degrees this is a summary because what we observed the pattern was strikingly similar the quantity is varied but the pattern was very very similar see if you imagine this to be a molar tube and this to be or incisor and this is the inter bracket span right so when I put a bend on this dot it is super close to the incisor so I get a huge amount of this blue line which is the incisor moment and also I am getting a huge amount of a moment at the Moller but because they are both in the positive side of the graph they're in the same direction okay now if I put a band here and this is the interesting one so I'll just you know confined mansur to this anywhere here you see that mesial to the molar up till this was approximately keep on going about 15 millimeters for sure so if you're putting a pen anywhere from molar till 15 millimeters mesial look at this blue line the blue line tells you the incisor moment value it is zero so if you had a wire and you are bending it like crazy like that and this band was somewhere in this region you're not producing any kind of this moment at the incisor it's zero and we tried it with a 2125 shopped in with a 30-degree band placed here and zero okay or very less I mean experiments do give you some values here or there or very less so that was super interesting for us to look alright so what we finally got out of it was these three classes and I'll go one by one so this is the one that I discussed with you so if you have a molar here if you have an sizer here and you place a bend anywhere in this region okay this whole span is approximately 30 millimeters so if you're anywhere in this region anywhere you place a bend you don't get a moment here all right it happened because this experiments we kept on doing for three or four years we in the clinic we were kind of you know using them just to see what we get in pure system so here's a patient is one of my patients who came in pretty early normally we don't do a lot of early treatment but we were like okay we'll put the braces on for two or three months and then you know get rid of them so our objective was let's dip this molar back and if possible create some space in that process get a class 1 and then we are done ok and of course we knew that normal leveling allowing with an eyetie will create some kind of you know leveling aligning or straightening of the teeth here so we went as 11 aligned little bit and then with a 1725 steal as you can see put a bend right here super close to the mold at you because we wanted this we wanted to tip the smaller back create some room for easier option of teeth and at the same time if we can create a class one why not so that is what we did and as you can see we got some intrusion here which works for us we don't mind that at all and we got some good tip back here so that fix that problem it was basically in for barely 2 to 3 months and then we put the patient on a holly retain or just to retain these Corrections so pretty useful I don't know if you guys have come across some of the literature by Thomas F Mulligan it's published as a Series in JC oh he used he uses a lot of this or used to use I guess I guess he's retired a lot of these techniques to treat his early phase or very young patients because you know in in early treatment you don't have access as such to these teeth because they are still erupting so you have basically a 2 by 4 setup so you can solve a lot of problems very easily in that way so this is one 1 you can say class of dents which is anywhere here you get the same for system the second class can be defined as in now if you move the bend from the midline so if this was my you know 15 millimeters from here now if I go further forward in about this much region which will be like 5 to 6 millimeters I hit a situation where you see the moments are kind of equal and opposite ok and there are some vertical forces created but not a lot so this is like the sweet spot if if you put a way Bend here you get maybe something here you get maybe something here all right and that is where we sometimes use our coves be right in that way and which I talked about that if you put a cover spheal Ike that maybe you'll get some moment maybe not but you won't get a lot this is very small value so maybe it is a lot maybe not if you want to create a bigger effect then as I told you need to flatten these ends out so make it flat and then you get a bigger effect and of course as we are talking about if you want to really torque these incisors then you move the bend further forward okay so when you move the bend further forward now you create a huge couple here and you get a big torquing effect the interesting thing we saw was that when you get a huge torquing effect here here the moment is also produced but it is in the same direction as this so basically your molar feeds a slightly tipped forward effect okay like that all right so that is pretty interesting thing to observe and this is how the picture looks in our experiment you see how the bend is super close to the incisor and you see this coupling that is happening here I've of course joined two images so this is not representing the actual span and here you maybe get a slight moment in the same direction maybe not it's not necessary you will so if you're in this region only that's when you get a huge torque on your incisor so can anybody by looking at this picture say what this configuration would be useful for so we use this a lot for molar attraction a lot like non tad base we do a lot of non tat based mole of attractions and we use this situation because that's what we learn from all this research that you can create so much moment here that the anchor loss is minimal or-or-or at times nothing zero so you see a big moment here so when you have a chain going from here to the molar I'll show you a clinical example too so that you get the full picture as to how it's happening so forces like this pulling the molar force like that so this force causes the incisors to actually dump right there dump like this so this moment is completely negated by this as a first principle rule it's very important to remember Anker loss happens due to tipping it never happens due to translation at least in the first couple of months so if you can control your tipping moments you can win over anchorage and that's the first principle rule it cannot be violated so this is the moment that you want to take this is the moment here that you want to take care of this dumping and so this does it very effectively here this works in our favor because it gives us this initial nudge for the molar to go forward so that is pretty useful and then of course the molar is going to walk on the wire but but it's a good system to start with it can also help in anterior cross-bite also that's another application that we have used it a quick clinical example to show the same design of my patients from my practice there were twin brothers actually and this picture I took in centric relation in centric occlusion this patient was a full class 3 so when I saw this we imagined that oh yeah if I can just you know torque these treat slightly forward and maybe extrude them I should be fine so what did we do we had these two brackets thought let's place a band as close as possible so what this did for me is exactly the force system shown here create this huge flaring and because this is a big moment here my vertical forces will create a counter moment in the system which will be expressed in the form of extrusion in the front and intrusion in the back so this is I call a fail-safe super appliance because even the side effects which is extrusion here and intrusion here is favorable for you so you don't mind it to keep on working for you this is intermediate picture when he started automatically positioning his bite correctly as soon as that he'd started flaring and then finally deeb and it took about seven months to eight months to get to this position incidentally this patient I've always kept on retention check he's now seventeen years old and he doesn't need braces so at this point I think at this point it was interesting when the patient came to us because remember this is centric relation so in centric occlusion he was full class three he had been suggested in the future might require surgery or face mask or zygomatic Anchorage for a face mask but he didn't get any in fact he didn't even get in braces more than six months so sometimes it's just so interesting to see these patients evolve alright so in summary this is what we got in terms of if you want to just remember us like out of all this work like what should I take away this is the slide that I would take away and we try to write this down in a clinically applicable manner in the sense we didn't want to attach a lot of numbers to it and if you want to make it even much more streamlined remembering the first and the third is perhaps the key because these are just the opposite right if you look at them the middle one is okay but these is what has got a lot of for us definitely a lot of clinical application in terms of the amount of time that I bend bending a v-- bend is like what one second or two second and it does so many different things so the summary of V bend interactions in one slide if you want to look at it that way that is what it is this is molar incisor this is two you can say molar premolar molar canine you know any second second order infractions so by second order I mean when you look at a bracket in this way and a wire is interacting like that this is a second order interaction so these are the rules for a second order interaction and these are the rules for a second and this is known as a third order so second and a third order interaction so this kind of encapsulate s' the whole idea about how to use MV bends