 Everyone, today we will be trying to understand balanced occlusion as a simulation on the articulator. Now balanced occlusion is preferred or is given in complete dentures and to understand why balanced occlusion is given in complete dentures we need to know the difference between natural dentition and complete dentures. In complete dentures the entire denture functions as a single unit unlike natural dentition where individual teeth have their own responses through periodontal ligament. So if you want to achieve good stability in complete dentures we have to achieve bilateral balanced and there are different concepts that have been put forth to achieve bilateral balanced occlusion. So the primary reason why we need to produce bilateral balanced occlusion in complete dentures is to achieve good stability. So bilateral balanced occlusion is defined as bilateral simultaneous occlusal contacts of anterior and posterior teeth during all excursive moments. So what you are seeing is the left and the right excursion on the mandible along with the protrusion that can be simulated exactly how a patient will be doing in the mouth. So when these excursions are done there should be contact of all the posterior and the anterior teeth. So this is what the definition basically wants us to do and this is what we want to achieve in a complete denture to produce good stability of the complete dentures. So two things that we need to keep in mind are when the mandible moves to the left and the right one condyle will be the rotating or the working condyle and the other condyle will be the balancing condyle. So we need to know which will be the working and the non-working condyle to understand if there are working and non-working contacts present in bilateral balanced occlusion. Now that we have understood why bilateral balance is required in complete dentures and to an extent understood the definition of bilateral balance there are certain characteristics that you will be seeing in a bilateral balanced occlusion. One there will be gliding contact starting from the incisors to the posterior teeth during excursive moments and when this excursion is happening there will be both working and non-working contacts. So this is the first characteristic and second is that when there is protrusion of the mandible when the mandible goes into protrusion there should be contact from incisors to the second molars. So there should be contact from incisors to second molars during both excursion and during protrusion. So when this is obtained we are going to achieve good stability of the complete dentures and this is what is expected out of a balanced occlusion. So different concepts have been proposed for achieving good bilateral balance. The most commonly followed is that of Hanau's concept or Hanau's quint. So Hanau has proposed five key factors in achieving a good balanced occlusion which are the Kondelar guidance which will be the Kondelar element on the articulator. The incisor guidance which will be determined by the incisor guide table on the articulator. Then the plane of occlusion, the cuspal inclination and the compensating curves which we will be looking in slightly furthermore detail. Let us look in detail about the components that was proposed by Hanau in order to achieve a good bilateral balance. Starting with the Kondelar guidance, the incisor guidance, the plane of occlusion, the cuspal inclination and the compensating curves. Kondelar guidance is basically the slope that the Kondel takes when the mandible goes into protrusion. So this will be replicated by the Kondelar shaft that is present in the articulator and the ball thing that you see over here will be the Kondelar element. So the Kondelar guidance is the only factor that is determined by the patient and which cannot be modified by the dentist. If this factor is obtained to be steep then there are certain problems and certain modifications that has to be done with the other factors. The Kondelar guidance will be obtained by the protrusive recall obtained from the patient. So the next factor will be the incisal guidance. The incisal guidance will be replicated by the incisal guide table and the incisal pin on the articulator. The incisal guidance is basically the influence that is produced by the lingual surface of the maxillary anterior teeth upon the mandibular anterior when the mandible goes into protrusion. So if we have to see the incisal guidance and how it works on the articulator we do this by retreating the pin on the articulator and we bring the mandible into protrusion. So the incisal guidance is a factor that can be modified by the dentist and it is primarily determined based on the aesthetics, phonetics and function of the patient. So the next factor will be the plane of occlusion. The plane of occlusion is determined during the jaw relations time where we keep the maxillary posterior rim parallel to the LR triangle line. So it is said that the occlusal plane should be tilted not more than 10 degrees in order to achieve a good bilateral balance. If it is tilted more greater than 10 degrees what will happen is there will be more tilting forces on the complete dentures and it will lead to destabilization of the dentures in the mouth. So moving on, the fourth factor will be the cuspal inclination and the last factor will be the compensating curves. So the cuspal inclination will be determined by the type of teeth that we use. It can be either anatomic, semi-anatomic or monoplane teeth. In anatomic teeth the cuspal inclination is around 33 degrees whereas in semi-anatomic it will be around 20 degrees and in monoplane teeth it will be 0 degrees of cuspal inclination. And the last factor will be the compensating curves. The compensating curves are of two types. One will be the anterior posterior curve and other will be the medialateral curve. So the anterior posterior curve in a complete denture will simulate the curve of speed that is present in the natural dentition and the medialateral curves will replicate the curve of Wilson and curve of Monson that is present in the natural dentition. So the significance of these compensating curves is that the positioning of the teeth should be done in such a way that they are positioned in this curve both anterior posteriorly and medialaterally. That is the positioning of this first molar should be in accordance with the anterior posterior curve and the medialateral curve that is going to be present in a natural dentition. So this is the significance and why we should be incorporating compensating curves in bilateral balance is to achieve stability in both excursive and protrusive moments. So I will be demonstrating bilateral balance on this articulator with this teeth arrangement. Now take a closer look. When I am doing the right excursive moment the working site contacts are established and simultaneously at this point if you look at the non-working site which will be this side of the teeth arrangement there will be non-working contacts also. So this will be for one excursion and similarly as we do the excursion on the opposite side there will be working contacts as well as non-working contacts also. So this will be the excursion and finally the most important one will be to look for protrusive contacts. So when we do for protrusion we will re-truth the pin on the articulator and we have to take a closer look at the cuspal slopes, the buckle and the mandibular and the maxillary cuspal slopes to check if there is protrusive contacts. So this is how we will be checking for bilateral balance on the articulator. The factors proposed by Hanoi that help us achieve good balanced occlusion are interrelated with each other and this diagram depicts their interrelation. The circle that is present at the center represents balanced occlusion and the arrow marks that are moving away from the center represent an increase in the value and the arrow marks pointing towards the center represent a decrease in the value. Now let us try to look at one square at a time and try to understand how the factors are interrelated with each other. Let us look at the portion where there is an increase in the inclination of condylar guidance. The condylar guidance is determined by the patient and the dentist does not have any role in its determination. So when the patient presents with an increased condylar guidance or rather a steep condylar guidance in order to achieve a good balanced occlusion you have to increase the cuspal inclination, increase the tilt of the occlusal plane and incorporate steeper compensating curves at the cost of a decreased incisal guidance. So this is how different factors are going to play a role for you to achieve a good balanced occlusion when one factor is trying to deviate from the center or trying to deviate from achieving a good balanced occlusion. So this concept holds true for all the other squares like for example when there is an increase in the incisal guidance there is going to be a shallow condylar guidance whereas the other values like the occlusal plane compensating curves and the cuspal inclination are going to be increased. So similarly you can understand how different components are interrelated and this understanding would be valuable for you to achieve a good balanced occlusion. So in the previous diagram we saw the relationship between the different factors proposed by Hanau in order to achieve a good balanced occlusion. If we had to concise the diagram we would be getting a formula that was proposed by Thielman where he stated that balanced occlusion is directly proportional to the condylar guidance and the incisal guidance and is inversely related to the compensating curves the occlusal plane and the cuspal inclination. Although Hanau's concept or Hanau's quint has certain drawbacks which gave birth to Trapezoanus concept Hanau's quint is still in use till today. I hope this video was helpful in decluttering certain concepts related to achieving good balanced occlusion and why we do good balanced occlusion in complete dangers. So that's it for this video. Thank you very much.