Dental caps

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Post on 28-Jan-2015



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<ul><li> 1. DENTAL CAPS / CROWNS &amp; BRIDGES Dental crowns, also referred to as "dental caps" or "tooth caps," are dental restorations thatcover over and encase the tooth on which they are cemented . Dentists make use of dental crowns when need torebuild broken or decayed teeth ,strengthen teeth , orimprove the cosmetic appearance of a tooth , Placing a dental crown on a tooth that has had root canal treatment. Crowns can be made out of porcelain (meaning some sort of dental ceramic), metal (a gold or other metal alloy), or a combination of both. Other terms that are used to refer to dental crowns are "dental caps" and "tooth caps."</li></ul> <p> 2. How can dental crowns be used to restore a tooth's shape? </p> <ul><li>Since a dental crown that has been cemented into place essentially becomes the new outer surface for the tooth it is easy to imagine how the placement of a crown can restore a tooth to its original shape. Dental crowns are routinely made for teeth that have broken, worn excessively, or else have had large portions destroyed by tooth decay and also for teeth treated by root canal treatment as inside of teeth becomes slightly weak as compared to healthy teeth. </li></ul> <ul><li>. What a disappointment it would be to spend the time, effort, and money to have root canal treatment performed, only to have the tooth break or crack irreparably before it was fully restored by dental crown. </li></ul> <p> 3. How can dental crowns be used to improve the cosmetic appearance of teeth? </p> <ul><li>Since a dental crown serves to cup over and encase the visible portion of a tooth, any dental crown that has a porcelain surface can be used as a means to idealize the cosmetic appearance of a tooth. Possibly you have heard it rumored (especially in past decades) that certain movie stars have had their teeth "capped." This simply means that the person has obtained their "Hollywood smile" by way of having dental crowns placed.</li></ul> <p> 4. How can dental crowns strengthen teeth? </p> <ul><li>The strengthening capability of dental crowns is related to the fact that they cup over and encase the tooth on which they are placed. This means that a crown can act as a splint that binds a tooth together. This is a very important feature of dental crowns and one that makes them a very valuable type of restoration for a dentist to have available to them.In contrast, dental fillings, especially large ones, can have a weakening effect on the teeth in which they are placed. Dental fillings rely on a tooth's remaining structure to hold and support them. Fillings, in general, don't strengthen a tooth and can't protect a tooth from the forces generatedby biting and chewing.</li></ul> <p> 5. What are the consequences of not protecting a tooth with a dental crown? </p> <ul><li>It's impossible to know precisely what the future holds for a tooth that seems to be a candidate for a dental crown. </li></ul> <ul><li>The tooth will experience no problems. </li></ul> <ul><li>The tooth will crack. </li></ul> <ul><li>1) Teeth that have cracked but no piece has broken off or has become mobile. The tooth produces no pain or discomfort.In many cases unless a portion of your tooth has broken off you may not be aware that a crack has formed. </li></ul> <ul><li>2)*Teeth that have cracked and no piece has broken off or has become mobile. The tooth does produce some pain or discomfort. </li></ul> <ul><li>Cracked teeth can be sensitive. Biting pressure can separate the portions of the tooth associated with each side of the crack and as a result trigger a painful response.</li></ul> <p> 6. 3) Teeth which crack and as a result have a portion that breaks off or becomes mobile . </p> <ul><li>Sometimes these teeth:</li></ul> <ul><li>are totally asymptomatic.</li></ul> <ul><li>are sharp or rough and therefore irritating to the person's tongue or cheek.</li></ul> <ul><li>have an increased sensitivity to hot and cold stimuli.</li></ul> <ul><li>are painful to biting pressure.</li></ul> <ul><li>are spontaneously painful.</li></ul> <ul><li>a) The tooth breaks in a fashion that is easily repaired. </li></ul> <ul><li>b)*The tooth breaks, but it requires other types of dental work before the dental crown can be made. </li></ul> <ul><li>The tooth fractures, root canal treatment is required.</li></ul> <ul><li>Deep tooth cracks or extensive tooth breakage can compromise the health of a tooth's nerve. In these cases your dentist cannot simply place a dental crown on the tooth. They must first performroot canal treatmentso to remedy the problem with the tooth's nerve, then thedental crown can be placed. </li></ul> <ul><li>c)*The tooth breaks in a fashion in which it cannot be repaired </li></ul> <p> 7. What steps are involved when dental crowns are made? </p> <ul><li>It typically takes two separate appointments for a dentist to make a dental crown for a tooth: </li></ul> <ul><li>I) The initial dental crown appointment. </li></ul> <ul><li>A) Your dentist will numb your tooth. </li></ul> <ul><li>B) Your dentist will shape your tooth. </li></ul> <ul><li>C) Your dentist will make an impression of your tooth. </li></ul> <ul><li>D) A temporary dental crown will be made for your tooth. </li></ul> <ul><li>E) Your dentist will select the proper shade of porcelain needed for your dental crown. </li></ul> <ul><li>II) Your second dental crown appointment. </li></ul> <ul><li>Cementing your permanent crown in place. </li></ul> <p> 8. TOOTH PREPRATION </p> <ul><li>Technique Tips</li></ul> <ul><li>Ensure even reduction of the anatomic form. </li></ul> <ul><li>Provide enough room for the ceramic to allow adequate strength. </li></ul> <ul><li>Sharp transitions and sharp internal edges/line angles or undercuts MUST be avoided. </li></ul> <ul><li>Margins should have a pronounced chamfer or shoulder with butt joint margins. Avoid tapered margins, feathered edges or bevelled shoulders. </li></ul> <ul><li>Ensure there is an adequate path of insertion. </li></ul> <p> 9. Suggested Margin Preparation Shoulder with rounded axio-cervical line angle, uniform circular ablation Chamfer preparation (with reduced mechanical support of the crown). Particularly used with reduced substructure (e.g., after repeated crowning). 10. Common Preparation Errors </p> <ul><li>Insufficiently defined and finished preparation margins.</li></ul> <ul><li>Uneven preparation limit ("gutter" preparation, vertical unevenness). </li></ul> <ul><li>Irregular marginal reduction of layers (horizontal unevenness). </li></ul> <ul><li>Wrong shape of preparation limit. </li></ul> <ul><li>Unnecessarily deep subgingival preparation. </li></ul> <ul><li>Preparation in root dentin. </li></ul> <ul><li>Poorly controlled tooth reduction. </li></ul> <ul><li>Excessive reduction, especially in the upper anterior teeth (vestibular) and premolars. </li></ul> <ul><li>Excessive incisal/occlusal reduction causing reduced retention and stability. </li></ul> <ul><li>Insufficient reduction at the palatal side of the upper anterior teeth (malfunction occlusion). </li></ul> <ul><li>Excessive taper. </li></ul> <p> 11. Common Preparation Errors Incorrect preparation of the labial surface: Preparation in one plane; therefore insufficient reduction of substance. Fracture of the crown may result due to insufficient wall thickness of the crown. Incorrect preparation of the labial surface, risk of damage to the pulp. 12. Effect of finish line variants on marginal accuracy and fracture strength of ceramic optimized polymer/fiber-reinforced composite crowns </p> <ul><li>Titre du document / Document title </li></ul> <ul><li>Effect of finish line variants on marginal accuracy and fracture strength of ceramic optimized polymer/fiber-reinforced composite crowns </li></ul> <ul><li>Auteur(s) / Author(s) </li></ul> <ul><li>CHO Leera ; CHOI Jongmi ; YANG JIN YI ; CHAN JIN PARK ;</li></ul> <ul><li>Rsum / Abstract </li></ul> <ul><li>Statement of problem. Ceramic optimized polymer (Ceromer)/fiber-reinforced composite (FRC) crowns have been promoted as alternatives to conventional crowns. However, little is known regarding the ideal tooth preparation for this type of crown. Purpose. This in vitro study evaluated the marginal adaptation and fracture strength of ceromer/FRC crowns with respect to the various types of finish lines. Material and methods. Four metal dies with different finish lines (0.9-mm chamfer, 1.2-mm chamfer, 1.2-mm rounded shoulder, and 1.2-mm shoulder) were prepared. Forty (10 for each finish line) Targis/Vectris crowns were fabricated on duplicated base metal alloy dies. The restorations were stereoscopically evaluated at 56 points along the entire circumferential margin for measuring the margin adaptation before and after cementation with a resin luting agent. The specimens were then compressively loaded to failure using a universal testing machine. The marginal adaptation ( m) was analyzed with the Kruskal-Wallis test and post-hoc Dunnett test ( =.05). The fracture load (N) was analyzed with a 1-way analysis of the variance and the Scheffe adjustment ( =.05). The fractured surfaces of the crowns were examined with a scanning electron microscope to determine the mode of fracture. Results. The</li></ul> <p> 13. </p> <ul><li>The marginal adaptation of crowns with a shoulder finish line was significantly better than crowns with a chamfer finish line before and after cementation (P</li></ul>