 So, today I am going to discuss in detail about mandibular major connectors. The main difference between the maxillary and mandibular major connectors is that maxillary major connector have a more area of contact and the another difference is that there are bead lines which are nothing but the minor elevations at the borders that contact the palatal soft tissues. When coming to mandibular major connectors, mandibular major connectors are long and relatively narrow and mandibular major connectors must not impinge upon the movable soft tissues such as the floor of the mouth, freina, mandibular tore and tongue. So the bead lines are not used as it may impinge the friable mucosa which may cause irritation, ulceration and patient discomfort. And for a dyslexic extension RPD a moderate amount of relief may be indicated because this type of processes tend to rotate during function. Next is the criteria for the selection of mandibular major connectors. There are basically six criteria. The first one is the requirement for indirect attention, second one is horizontal stability and stress distribution, third one is anatomical considerations. The fourth one is aesthetics, fifth one is contingency planning and the last one is patient preference factor. There are basically six types of mandibular major connectors. They are lingual bar, lingo plate, sublingual bar, kennedy's double bar, singlum bar and label bar. Out of this the lingual bar and lingual plate are commonly used. So the first one the lingual bar mandibular major connector, it is the most frequently used mandibular major connector. The basic form of a mandibular major connector is a half pier shape located above the moving tissue as far below the genitalia tissue as possible. So it is a single bar situated above the moving tissue that is away from the floor of the mouth and it is as far below the genitalial margins of the tooth. Moving to the characteristics and location it is a half pier shape with the bulkiest portion inferiorly located that is it is the most bulkiest portion of the lingual bar is inferiorly located and the superior border is tapered to the soft tissue and located at least 3 mm inferior to the genitalial margins. The inferior border is located at the ascertain height of the alveolar lingual sulcus when the patient's tongue is slightly elevated. And next is the availability of space. To accommodate the lingual bar at least 8 mm of vertical space must be present between the genitalial margins of the tooth between the genitalial margins of the tooth and the floor of the mouth. So this perme is the major connector to have a minimum height of 5 mm and allows 3 mm of space between the genitalial margins and the superior border of the bar. And failure to provide a 3 mm of space may lead to irritation of adjacent soft tissues and in clinical setting the available space may be measured using a pedodontal probe. Advantage is the lingual bar connector has a minimal tissue coverage and has minimal contact with oral tissues. So it decrease the plaque accumulation and increase the soft tissue stimulation. It does not contact the teeth so the decalcification of the tooth surface is minimized. Disadvantages it may be flexible if poorly constructed and rigidity is less compared to a well constructed lingual bar. Moving to the indications where sufficient space exists between the slightly elevated alveolar lingual sulcus and the lingual insoluble tissues always give a lingual bar. Contraindication in cases of inoperable lingual tori highly attach lingual freedom in difference to the elevation of the floor of the mouth during functional movements. In all those conditions the lingual bar is contraindicated. So the next mandible major connector is lingual plate. The other names of lingual plate are lingual plate, lingual strap, lingual apron and lingual sheet. The lingual plate must be used when a high lingual freedom or the floor of the mouth prevents the use of a lingual bar. So whenever the lingual bar is contraindicated the lingual plate must be used. The lingual plate is nothing but a half pier shaped lingual bar with a thin sorrel piece of metal extending from the superior border. And this thin projection of metal is carried into the lingual surface of the teeth and present a scallop appearance. And it may be used in combination with a label bar for sprinting and the thermal tooth rest should be used to provide a vertical stop at each end of the lingual plate to prevent the label movement of teeth. Location it is a half pier shape with the bulkiest portion inferiorly located but it is less bulkier than the lingual bar. Thin metal apron extending superiorly to contact the singular of anterior teeth and height of contour of posterior teeth. Scallop contour of apron are detected by indeproximal blockout. The superior border finished a continuous plane with contact teeth. The superior margins of the scallop metal should be knifed to avoid the ledging effect on the lingual surface of the teeth. In patients with open embrasures or anterior teeth are widely separated. Modification of lingual plate may be indicated and this is not a step back design. But the steps can be designed to avoid an unwanted display of metal. So in this case the superior border covered the singular of indicated teeth only and the inferior border must be made rigid. If the inferior border at a certain height of the aloe lingual sulcus when the patient's tongue is elevated. Next is the indications. When the aloe lingual sulcus law closely approximates the lingual gingival crevices such as the high lingual free enough attachments. That is when there is decreased vertical space available the lingual plate is indicated. Second one, if residual ridges in class 1 arch have undergone severe vertical resorption that they will offer only minimal resistance to horizontal rotation. It can be used to stabilize predominantly weakened teeth. And the last one is when future replacement of 1 or more incisor teeth will be facilitated by the addition of retentive loops to an existing lingual plate. So as the teeth are lost instead of making the processes retentive loops may be soldered to the lingual plate and the prosthetic teeth may be added to the RPD. So it is contraindicated in lingually inclined mandibular anterior teeth. Advantage is the lingual plate is a rigid mandibular major connector and it provides more support and stabilization when compared to other connectors. It can be used in stabilizing predominantly weakened teeth and when it is supported at each end by a rest it contributes to the action of indirect attention. So it also provides indirect attention. Patients with existing mandibular taurine in such cases the lingual plate can be indicated and it has exceptional rigidity and when properly conduit and fabricated it will not cause interference with the tongue movements and will be more comfortable to the patient. Disadvantages it covers the tooth surface and the residual tissue and as it covers the tooth surface it may cause recalcification of enamel surfaces and irritation of the soft tissues with in patients with poor oral hygiene. The mental coverage of the fridge enjoyable tissue prevents the physiological stimulation and self cleansing of these areas by saliva. Sublingual Bar Mandibular Major Connector it is a modification of the lingual bar that is used when the height of the floor of the mouth does not allow the placement of the superior border of the connector at least 4 mm below the fridge enjoyable margin. Characteristics and location it is famous lingual bar except that it is placed more posteriorly and more inferiorly than the lingual bar. The superior border of the bar should be at least 3 mm from the fridge enjoyable margin and inferior border is located at the height of the alveolar linguit surface. Indications the height of the floor of the mouth in relation to the fridge enjoyable margin is less than 6 mm. If it is designed to keep the fridge enjoyable margins of the anterior teeth exposed and there is inadequate depth of floor of the mouth then the sublingual bar is indicated. Contraindications in case of lingering tilted remain natural teeth and case of inoperable lingual taurine and highly attached lingual phrenum in all these cases the sublingual bar is contraindicated. Contraindicated lingual bar with continuous bar or mandibular lingual bar with single bar or double lingual bar or split bar. So this type of mandibular major connector is also called Kennedy bar because it distributes stresses through all of the tooth with which it comes in contact thereby reducing the stresses to the underlying tissues. It is also known as the continuous lingual class major connector because of series of lingual clasp arms connected on to the lingual surfaces of lower anterior teeth. Characteristics and location it has both the characteristics of lingual bar and lingual plate. Thin narrow metal staff located on singular of anterior teeth scale up to follow the interproximal embrasures. The position and contour of upper and lower border of the double lingual bar are similar to those of a lingual plate which is not joined by a continuous sheet of metal. The lower bar is half pier in cross-section with the greatest diameter at inferior margin and the upper bar is half oval in cross-section with two to three mm height and one mm thick. The two bars are joined by rigid minor connectors at each end. Indications a double lingual bar is indicated primarily when contact with remaining mandibular anterior teeth. It is mainly used as a major connector in peldonally treated anterior teeth with wide interproximal embrasures. When lingual plate is contraindicated due to the poor axial element of anterior teeth the double lingual bar is indicated. Contraindication it is contraindicated in severely corroded anterior teeth. Advantages it has advantages because it has an amount of indirect attention and the horizontal stabilization. Disadvantages tendency to trap the debris and patient discomfort as it may cause irritation to the tongue. Mandibular continuous bar retainer or singular bar. Improper axial alignment of the anterior teeth will necessitate excessive blockout of interproximal undercuts. These type of cases will indicate the use of continuous bar major connector. It is located slightly above the singular of the anterior teeth and can be used alone or with a lingual bar. Step back design is followed for diastema patients. Contraindication it is contraindicated in case with lingually tilted anterior teeth and where wide diastema between the mandibular anterior teeth exists. Characteristics allocation it is a thin metal strap located on the singular of anterior teeth scale up to follow in the proximal embryos. Origin is bilaterally from the rest of the adjacent principal abadments. Next is the mandibular label bar major connector. The label bar has limited application. It is used mainly where the inoperable lingual tore and severely lingquilly inclined lower anterior and premolars prevents the use of all other major connectors. It is basically a label bar on the facial aspect of the mandibular arch. It is half pier shaped when viewed in cross section. Label bar is longer than corresponding lingual bar, double lingual bar or lingual plate. To ensure rigidity the height and thickness of a label bar must be made greater than those of those described for a lingual characteristic location. It is a half pier shape with the bulkiest portion inferiorly located on the label aspect. The superior border tapered soft tissue and 4mm inferior to label irringible margins inferior border located in the label buckle vestibule. And the modification of label bar is the hinged continuous label bar. This type of major connector is a modification of lingual plate which is incorporated in the swing block design which consists of a label bar that is connected to the major connector by hinge on one end and latch on the other end. Swing lock RPD was introduced by J Simmons in 1963 and represents a useful modification of label bar. Here the label compound does not serve as a major connector. Instead the modified label bar has a hinge on one end. It has a hinge on one end and locking device on the other end and it permits an opening and closing action similar to that of a gate. So when the gate is an open function open position the framework is seated in the patient's mouth and when it is complete seating is occur the gate is closed. So it reads all the inaccessible undercuts. Support provided by multiple trust on the remaining natural teeth stabilization and reciprocation provided by lingual plate. Retention is provided by bar type retentive class firms projecting on the label or buckle bar and contacting the intra bulge areas on the label surfaces. Indications it is indicated in missing key abutments unfavorable tooth contour, unfavorable soft tissue contours and teeth with questionable prognosis. Contra indications in case with poor oral hygiene, shallow buckle label vestibule and high frugal attachments. It also causes discomfort to the lower lip. Label vestibule which is usually not deep enough to permit a rigid major connector without encroaching on the free marble. Then next moving to the design of mandibular major connectors. The basic principles of major connector design includes outline the basal seat areas on the diagnostic cast. So the basal seat areas are outlined on the diagnostic cast. Second step outline the inferior border of the major connector. Third one is the outline the superior border of the major connector and fourth one connect the basal seat area to the inferior superior borders of the major connector and add minor connectors to retain the acrylic resin base. Materials used for major connectors the various alloys that can be used in constructing the removable partial denture framework are type for gold alloy, nickel chromium, cobalt chromium, cobalt chromium nickel and titanium and its alloys. Out of this the basement alloys which are cobalt chromium and nickel chromium have relatively high elastic modulus. This property suggests that the thickness of partial denture frameworks can be thinner than those of other metals. The ductility of titanium is greater than that of the others. Base metal alloys have higher hardness compared with tooth enamel which causes invibor wear. Alloys for partial denture frameworks have high melting points and they exhibit high casting shingles with potential for casting defects. So moving to the conclusion the major connectors it should be made up from an alloy which is compatible with oral tissue. It should be rigid and provide process stability through the principle of broad stress distribution. Test note interfere with and it's not irritating the dunk and does not substantially alter the natural contour of the lingual surface of the mandibular alveolar ridge or of the palatal vault. Test note impitch on the oral tissue when the restoration is placed remote or rotating function. It covers no more tissue than is absolutely necessary. Test note contribute to the retention or trapping of food particles and it has support from other elements of the framework to minimize the rotation tendencies in function. It contributes to the support of the processes. So with this session I'm going to load in the major connectors. Thank you.