Metal free ceramic crowns

Metal free ceramic crowns one of the most aesthetic dental crowns in the market, where instead of a metal substructure, a ceramic batching is used as the base of ceramic, it has the advantage that it doesn’t from a black line along the gum margin, due to the corrosion of metal backing along the cervical margins of the metal ceramic crowns. But metal free ceramic crowns has the disadvantage that they fracture easily when masticatory forceses are exerted on them. Provided gum recessions, which can form due to age, improper maintenance of oral care along the gum margins of the dental crowns are also seen in metal free ceramic crowns also. Metal ceramic crowns Ceramic fused to metal has the strength of metal and aesthetes of ceramics ceramic fused to metal restorations has an initial coping which fits over the stump, over which ceramic is added. The metal coping will be a thin layer at the gingival margin, and certain times a small part of the metal is removed and instead ceramic is added over that area. Metal ceramic crown has three layers, an opaque porcelain to mask the opaque colour of metal body porcelain and incisal porcelain. One of the major reasons for acceptance of ceramic fused to metal crown, was due to the strength of metal and its ability to bond to the ceramic metal. But one of the major disadvantages of metal ceramic crown was the formation of a black line along the cervical margin due to the exposure of the metal to oral fluids and formation of corrosion products this affecting the aesthetic appearance of the crown.

Natural tooth can last decades or even your entire life, it they are cared for properly, provided natural tooth can be retained by preventive Dentistry, restorative Dentisty, or even through root canal treatment with a dental crown and at certain times by a dental post.
Advantage or retaining natural tooth
The function of your smile will be much better with natural tooth, than artificial (prosthetic) tooth. Even through dental bridges and implants can give a good appearance some thing that is natural cannot be replaced by artificial means. Provided there is no difficulty as such of removable dentures, which has to cleaned for removal and even kept out of the oval cavity during night. Retention of natrual teeth is cheap in the long run. A mouth without tooth is like a mill without a blades natural tooth are precious and should be lead to preserved at any cost, by the various treatment modalities which are available for us in the Dental fraternity.

Contact and contours are an important part of crowns, these contacts and contours act as spill way for food and prevent food passage into sublingual area. The contact area proximally on molar tooth is located to the occlusal third, except for the second molar, which is located to middle third. The contact area should be than just a point and is normally an area. The area cervical to contact area should be flat or concave and never should be convex, since that can course gingival inflammation. The proximal contacts are slightly facial to the contour except for the maxillary 1st and 2nd molar which is pretty centralilised. If the contact area is to narrow, it can act as a area of food wedging especially for fibrous foods, and if the contact area is too wide facio-lingually, they do not deflect food from gingival tissues. The height of contour or the facial surfaces of all posterior tooth occurs in the cervical third and similar in the lingual surfaces of maxillary premolars and maxiillary molars.On mandibular tooth on the lingual side, this height of contour occur in the middle third. The amount of lingual curvature varies from 0.5mm on maxillary molars and mandibular 1st premolars and 0.75mm on mandibular 2nd premolars. It is 1mm on mandibular molars. The contours of tooth play on important role because over contouring of tooth can cause food accumulation on cervical area and gingival inflammation.Thus the importance of proper contours in crown is mandatory for preventing food impaction and food accumulation and thus promoting good gingival health.

A peri apical lesion of dental origin can be due to a long standing chronic caries, history of trauma on tooth and improperly done root canal treatment. Earlier peri apical lesions where managed by apicectomy (surgical removal of the apical third and a retrograde filling) which used to get dislodged and happen to get re infected. With the advent of better techniques in root canal treatment, the management of such tooth became easier and were successful with predictable results. Such involved tooth where managed non surgically by re-root canal treatment, and where followed by x-rays in a period of three months, six months, and one year.Large cyst of Endodontic origin where managed by removal of the cyst, than apicectomy (where the apical third of the tooth where surgically removed) With the introduction of newer instrumentation techniques and instruments and epoxy resin and bio ceramic root canal sealers, the need for apicectomy was avoided with proper root canal and re-root canal treatment being carried out with ease.

Oral habits in children is a concern for Dentist, as well as the paediatrician, speech therapist and parent. Regarding the dentist part the habits such as thumb sucking, tongue thrusting can result in the changes of the alveolar ridge, potential problems in position of teeth and development of malocclusion which can be due to prolonging of abnormal habits. The problem is that the Dentist rarely sees the child earlier and only by the time the habit has established and damage to the teeth in the form of malocclusion of teeth. Tongue thrusting is defined as a human behavioural pattern where the tongue protrudes through the anterior tooth during speech and swallowing. Thumb sucking is a procedure where the thumb is inserted into the mouth and where a pleasure is obtained for the individual, Both these habits can lead to dexterous effect in the oral cavity if the habit pursuit beyond the exception of the permanent teeth. Tongue thrusting can be due to hyper plastic tonsils, prolonged thumb sucking, nasal congestion, macroglossia and secondary to early extraction of deciduous tooth and an anterior open bite. Treatment of Thumb sucking and tongue thrusting The treatment of tongue thrusting primarily involves, the correction of cause, once the cause is corrected, the tongue musculature can be controlled by muscle retaining an exercise technique, which redirects the muscle associated with swallowing. Mechanical restraining method where an appliance is placed in the mouth which will restrain the tongue and thus preventing it pushing forwards wing mechanical retainers such as cribs. While thumb sucking is performed for oral satisfaction, serve thumb sucking can lead to proclamation of maxillary anteriors, constriction of the maxilla, retroclination of lower actions and an increased over jest and open bite. Usually following the thumb sucking, tongue thrusting can develop as secondary.

Our mouth is full of bacteria, which along with the food debris and other substances form a colourless sticky layer on tooth called as plaque which can be removed by brushing and flossing. Once it hardens it is called as plaque, which can be removed by a Dental professional only. The longer the plaque and tartar are on the tooth, more troublesome it becomes. The bacteria in the tartar cause gum inflammation, which is seen as gum swelling and bleeding. This form of gum disease can be reverted back by proper oral prophylaxis by a dentist, and regular brushing and flossing which can prevent bone loss and periodontal tissue breakdown. When gingivitis is left untreated it spreads to periodontitis due to the damage caused to the supporting structures of the tooth, by the bacterial toxics which are produced by the plaque bacteria and also assisted by the inflammatory responses of the body mechanism, which eventually damage the supporting structures of the gingival tissue and the alveolar bone. If left untreated it can end up in loss of the tooth.
Treatment plan
Periodontitis can be diagnosed by clinical examination using a periodontal probe and by radiographic examinination of bone loss. Periodontitis are painless and will be noted at a later stage only if individual is careless.
Preventive measures
Proper brushing twice a day, such a way that the bacterial plaque is disrupted and proper flossing daily.

Dental Composites
A new era in Dental restorative materials began in 1955 when Bunocre found that acrylic resin formed acceptable micro mechanical adhesion with dry dental canal that had been etched with phosphoric acid. Most Dental restorative resin systems are based on UDMA or BISGMA materials, with an added filler particles, which determines the final property of the composite which include the shade opacites, translucency and polish ability of the composites. When the flow of composite increases, the amount of filler particle is reduced, such composites have the disadvantage that the co-efficient of thermal expansion is more, leading to micro leakage and secondary caries, along restoration margins. Hybrid are a combination of micro fills and larger filter particles sizes the disadvantage is the inability to polish. Presently Nano hybrid Dental composites are the dental composites in the market, the choice of dental composites. Tooth coloured filling material should be decided by physical properties, amount of filler particles and size of filler particular, which decides the polish ability of the dental composite.
Advantages
It includes esthetics, which is one of the prime factor of composite restorations. Less tooth reduction when compared to amalgam restoration and it is insulative in nature and are added advantage is that it can be repaired when fracture of restoration occurs.
Disadvantages
The major disadvantage of composite is the shrinkage of composite, which is decided by two factors. The quality of Bond The shape of cavity The shape of the cavity effect in shrinkage of dental composite depends on the ratio of the bonded to unbounded surface of the preparation. The stress on the restoration increases, as the amount of bonded surface increases a class I restoration has five bonded and as unbonded surface. Taking into consideration of biocompatibility matter of dental composites, they cannot be placed in deep cavity directly, such deep cavities should be protected with a insulate barrier such as glass ionomer to protect pulp tissue. For a successful composite restoration, adequate time should be spent, curing each increment, provided a properly functioning light unit should be used and light guide should be as close as possible and at right angles to the material being photo curved.
Dental Amalgam
Dental amalgam is an alloy of silver tin, and small amounts of copper to which mercury is added. Depending on the amount of copper added it can be divided into high copper and low copper amalgam. High copper amalgam has better corrosion resistance than low copper amalgam. Depending an particle size Dental amalgam can be classified as i) Spherical or (ii) spheroid. Depending on Presence of copper (i) high copper are (ii) low copper Amalgam has its properties such as excellent compressive strength, but once the dental restoration of amalgam factures due to occlusal load, correction of such a filling is difficult and the whole filling should be replaced. Dental composites or Dental amalgam has its our merits and disadvantages but at the end of the day the individual wants a filling which is stable and with out causing him any pain.

Site selection
The importance of site comes to play in bone quantity, quality and forceses of mastication the bone is subjected to, and close proximity to Endodontic restorations, which helps the Dentist to go far an implant, or avoid an implant. If going for an implant, the length and width of the implant choosen matters in bone selection. Bone augmentation or bone grafting which needs to be done in certain situations, can be a failure in the situations like osteoporosis periodontial disease or even infection which can affect the integrity of bone formation. Provided the timing of the placement of the implant in the grafted bone is important, time should be given for the grafted bone to mature and usually it takes 6-12 months for lamellar bone, which can adhere to implant interface. Bone grafting can be successful procedure, provided adequate blood supply to the area and micro movement of the implant doesn’t occur during the osteointegration stage.
Occlusal Forceses
Implants being ostio intergrated with bone doesnt have periodontal support as natural tooth, so shear forces are damaging to the implant. The implant and corresponding tooth should be designed in such a way that forces should be directed along the long axis of the implant, such a way that shear forceses are prevented from acting on the cervical margin of the tooth, especially on the buccal side of the implant. Forceses along the long axis of the implant are well tolerated, but shear forces not good, it can lead to bone loss on cervical area. Sites which are more posterior are subjected to more occlussal forces since they are close to the fulcrum of the mandible.
Implant Design (Factors)
Length of implant Average length of the implant used varies from 10-16mm, longer implant better bone contact which improves the stability of the implant to occlusal forces. Width of the implant Increase in width of the implant with grooves in the implant make the surface area contacted by the implant increases, which increases the stability of implant to occlusal forceses A healthy gingival sulcus of 3-4mm should maintained between the implant and crest of the alveolar bone. An implant placed next to a tooth should be at least 3 mm apart so as the provide adequate blood supply to the periodontal ligament. Implant to implant should be placed 4-7mm, to prevent bone necrotic and thus failure of implant.
Surgical Technique
When bone is exposed to temperature of (470C) for more than 1 minute, it results in collagen damage, bone necrosis and eventually death of bone, which results in collagen adhering to implant and bone, than proper osteo integration. This can happen when excessive pressure and excessive speed is applied during the drilling procedure of the implant, insufficient coolant is used during the drilling procedure far implant. Using a surgical length no. 2 round bur, the density and thickness of the bone can be evaluated.
Time of implant loading
Implant should be loaded depending on the density of the bone, from a period of four months to one year. Early loading can affect osteo- integration along the implant and finally the implant can end up in failure due to fibrous collagen formation between the implant and bone. Occlussion should be adjusted such a way that excessive forcesses should not be directed on the implant which can effect the ostiointegration of the implant. Provided the oral hygeine of the individual can affect the life of the implant, due to improper plaque removal and not using interdental cleansing aids, which can cause gum inflammation.