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I hope that you all are doing fine. Now in this video, we are going to talk about the balanced occlusion. Now this topic is a bit difficult, especially for the undergraduate student, but don't worry, I'll try to make it as simple as possible.
So please do subscribe to my channel because it really motivates me to create more helpful videos of this kind. And also let me know in the comment section below if you find the video helpful and what next topic you want me to Cover. Now to understand the balanced occlusion, first we need to understand how our natural teeth are. Okay, so just imagine this on your teeth. Try to bring your mandible forward so that your incisors are edge to edge.
You will find a space in your posterior teeth, a wedge shaped space will be present in your natural teeth. Okay, so that is the Christensen's phenomena, right? But if we have a similar thing in a complete denture what will happen if you have a same space the denture will lift okay the lower denture will lift up the upper denture will lose retention and this will not be balanced so in complete denture we don't want the spacing in any movement whether it's protrusive means whether the patient is bringing his mandible forward or side to side any movement we want at least three point contact okay we need one anterior contact and two posterior contact.
So, if you have this three-point contact, the denture will remain stable because no matter what kind of movement the patient is making, we will always have a three-point contact that will make the denture stable, okay? So, that is a balanced occlusion. Now, by definition, it is a bilateral, simultaneous, anterior and posterior occlusal contact of teeth in centric and eccentric position.
okay so let's focus on this definition it is a bilateral means both side simultaneous means together anterior and posterior occlusal contact okay so here we are talking about the occlusal contact of teeth and that contact is bilateral means it's on both side it is simultaneous means occurring together and it is anterior and posterior okay so we have at least three point contact in In centric. and eccentric position. What is centric?
See, what is centric occlusion? It is the occlusion of the opposing teeth when the mandible is in centric relation. Okay, now what is centric relation? It is a bone to bone relation.
You must have been asked to memorize this big definition that it is a maxillomandibular relationship independent of tooth contact in which the condyles articulate in the anterior superior position against the posterior slope. of the articular eminence. In this position, the mandible is restricted to a purely rotary movement. From this unrestrained physiologic maxillomandibular relationship, the patient can make vertical lateral or protrusive movement.
It is a clinically useful repeatable reference position. Okay, so just pause this video for a while and have a look at this definition. Okay, that is the centric relation. Now, centric occlusion is the occlusion of the teeth when the mandible is in this centric relation. Okay.
Now, coming back to our balanced occlusion definition, we saw that it is the bilateral simultaneous anterior and posterior occlusal contact of teeth in centric and eccentric position. Now, what is eccentric? Any position that is other than the centric is the eccentric position.
So, now we know that what is a balanced occlusion. So, Such patients who have balanced occlusion, in centric occlusion also, they will show posterior contact of the teeth. During lateral movement also, we will have posterior tooth contact and even on protrusion, there will be posterior tooth contact.
So, in all kinds of movement, we have three point contact on the tooth and that balances the denture. What is the advantage of giving balanced occlusion? The denture will be stable and why is this important because it increases the stability of a denture. Also, it prevents the denture bearing area from unwanted forces. Imagine lifting of the denture again and again.
This movement of the denture can cause soreness in the denture bearing area and also can lead to increased resorption. Okay, so that is why balanced occlusion is important. Now there are five factors which affect the balanced occlusion. This is the Kondylar guidance.
The incisal guidance, orientation of the occlusal plane, the compensating curves and the cuspal inclination. So these five factors, they affect the balanced occlusion. And these are described as the Hanau's Quint.
Now let's have a look at each of these factors one by one and try to understand them. The first one is the condylar guidance. So here we have the condyle of the mandible and this is the articular eminence. Now when the mandible translates forward okay you can see that there is separation in the posterior teeth right.
If it is translating like this the separation is this much. Now what if we had a steep condylar guidance. Now when we have a steep condylar guidance the condyle will glide like this okay. So now you can see that the separation is a lot more.
Okay. Can you see? So in this case, what we need, we need to have a cusp that are longer so that we have a posterior tooth contact, right?
So when we have a shallow condylar guidance, in that case, there will be less separation of the posterior teeth. So when there is less separation, we need shorter cusp and flatter fossa to get our balanced occlusion. But on the other hand, If we have a steep condylar guidance, we will have more separation in the posterior tooth.
Okay, so in that case, we will need longer cusp and deeper fossa to get our balanced occlusion. So that is about the condylar guidance. Now condylar guidance, it cannot be changed by us because it is a bone to bone relation, right?
We cannot change it. What we can change is the teeth, right? Because we are doing teeth setting.
in the denture. So we can change this but not the bone to bone contact. Now let's talk about the incisal guidance.
Now if we have a closer look at the incisors, here we can appreciate incisal guide angle. Now this is an angle which is formed between the horizontal plane of occlusion and a line drawn in the sagittal plane between the incisal edges of the maxillary and mandibular central incisors when teeth are in maximum intercuspation. So, here we have a maximum intercuspation and at that point the angle which is formed between the horizontal plane of occlusion and we draw a line in the sagittal plane between the incisal edges of the maxillary and mandibular central incisor. Now, if this angle is steep and we try to move the mandible forward, you will see that there is more posterior tooth separation. So, when we have more tooth separation posteriorly, what will happen?
We will need a steep cusp, longer cusp. We will also need steep occlusal plane and compensating curve about which we'll be studying just little later in this video itself. So, if the anterior teeth are more proclined, that means we have a steep angle. Now, when this angle is steep, if you try to bring your mandible forward, what will happen? This will create a lot of spacing in the posterior.
So for that, to compensate for that, we need to have steep cusps. In addition, we will also need a steep occlusal plane and also a steep compensating curve. So we have to make sure that we don't have such a steep angle here.
It should be as flat as possible, as long as aesthetics and phonetics are not compromised. Now, when we have a steep vertical overlapping in the anterior teeth, what we can do we can increase the horizontal overlap to compensate for this so because of this the incisal guide angle will reduce as you can see here right then we come to the orientation of the occlusal plane now anteriorly the lower canine the height of the lower canine it establishes the occlusal plane and this coincides with the commissure of our mouth And posteriorly this orientation is established by the height of the retromolar pad. Also remember that while we are doing the orientation jaw relation we make sure that our maxillary rim is parallel to the allotragus line, right?
So when the maxillary rim is parallel to the allotragus line, our mandibular rim will also be parallel, right? So it can be related to the allotragus line as well. Then we have the compensating curve. Here we have two types of curve, the anterior-posterior curve and the lateral curve.
Now anterior-posterior curve, as you can see here, it runs from anterior to the posterior so it helps in maintaining the protrusive balance while the medial lateral curve as you can see here it runs side to side means in the lateral direction so it helps in obtaining the lateral balance see curve of p is anterior posterior curve means we arrange the teeth in such a way that we get a curve starting from the tip of the canine running posteriorly till the molar. Now imagine if we don't have this curve, if this is just a flat plane, okay, what will happen? Again, when the patient is in protrusion, there will be a wedge-shaped space in the posterior region and the denture will fall, okay. I mean the denture will be less retentive. So, we are again facing the Christensen's phenomena here which is and which should be only in the natural teeth.
not in the complete denture. In complete denture, we want a tripod contact, right? We want a three point contact.
So, to get contact posteriorly, we are curving the teeth arrangement, okay? Now, coming to this medial lateral curve, which is a curve of Wilson. So, as I said, this will maintain the balance in the lateral movement, side to side movement. How? See, let us suppose you shift your mandible towards this side.
Okay, so if we have the tooth arranged in such a way that the buccal cusp, both the buccal cusp of the left side and the right side, they are higher and the lingual cusps are little lower, they will be contact on both the working side and the balancing side in the lateral movement. So that is how the medial lateral curve, it maintains the balance when we are doing side to side movement. Just few minutes back, we had talked about the plane of occlusion, which was established in relation to the Allard-Tragus line, right? Now, that plane of orientation, that serves as a starting point while we are placing the second molars and the incisors.
So, they are basically the starting point for the vertical placement of the second molar and the incisor. Okay, but this plane is temporary because when we establish this curve, okay, this compensating curve when we establish them, this plane, this plane of orientation is usually lost. So, this plane of orientation is just a starting point and is usually lost when we establish the compensating curve. Now, compensating curve, I will take another dedicated lecture on this topic.
The last one is the cuspal inclination. It is the angle which is made by the average slope of a cusp with the cusp plane. measured mesodistally or buccolingually also called the cusp angle.
I'm including the GPT definition so that it can help you in memorizing. Now let us consider these two teeth. Now this second molar it is closer to the condylar guidance compared to this one right. So a closer a tooth is located to the condylar guidance the more influence this will have on it.
okay so this condylar guidance will have more influence on the cuspal inclination of this tooth compared to this tooth similarly this is our incisal guidance right now here this is reversed this tooth is more close to the incisal guidance so the incisal guidance will have more effect on the cuspal inclination of the first molar compared to this one okay So the incisal guidance will have more influence on the cuspal inclination of first molar compared to the second molar, just opposite of what we had seen here, right? So the anterior posterior inclination of the tooth, it will depend on the distance. It is located from the condylar as well as the incisal guide.
And if a tooth is closer to the condylar guidance, the condylar guidance will have more influence on these tooth compared to the incisal guidance. But if a tooth is more close to the incisal guidance compared to the condylar guidance, then the incisal guidance will have more influence on this tooth. I hope I made it clear.
So after completing the teeth arrangement, when you look at your teeth setting from the front, you will realize that there is increasing buccolingual inclination from the premolars all the way to the molars. And when you look at your teeth setting from the lateral side, you will again see an increasing anterior-posterior inclination. So we learned that all these five factors are interrelated to each other.
The condylar guidance, we cannot change it because it is a bone to bone relation and it varies with the patient. We just have to record it by taking the protrusive record of the patient and adjusting our articulator. The incisal guidance also can be just changed a little because it affects the aesthetics and the phonetics of the patient. It is usually near zero degree and we have to make sure that The incisal guidance is not more than the condylar guidance in any case. The plane of orientation can also be changed a little bit.
But the two things that are fully under our control is the tooth inclination and the compensating curve. So, these are the two main things we can change as a dentist and we can give a balanced occlusion. Now, all these five factors have been very beautifully organized in the Hanau's.
Quint about which we will be studying in the next video. Also, the compensating curves can be talked about in more detail. So, let me know in the comment section below which one you want me to cover first.
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