Differences: composites, inlays/onlays, crowns

yes, i am aware you didn't say they last 18 months.

there are criteria for using them. if a person wants them despite only having a smaller cavity, they can sometimes talk their dentist into as long as they understand the tooth structure they must give up to get them. i think the newer cad/cam inlays/onlays are adhering better to teeth, now, perhaps lessening the amount of tooth structure to be taken off.  but, dentists don't want their fillings falling out, so that is why composites are often the best choice for small to medium fillings.

What are porcelain inlays/onlays? Do they replace a crown or cap?

Porcelain inlays and onlays are custom lab fabricated restorations that are placed in teeth that are too broken down for a filling to be placed. They are extremely esthetic and natural looking and help hold a badly broken down tooth together, actually strengthening it. In some cases they can be used instead of a crown or cap as a more conservative approach to restore a broken down tooth.

http://www.nycsmiledesign.com/New_York_City_Cosmetic_Dentist/dental_faqs.htm

Inlays, onlays and crowns- what's the difference?

The CEREC machine can make all three of these porcelain restorations. The difference between inlays, onlays and crowns is the amount of tooth structure they replace. If you look at a tooth from the chewing surface, the raised bumps you see are called cusps. When you chew your food, it is the cusps of opposing teeth which grind and mash your food. Restorations which fit within cusps are called inlays, and those which incorporate a cusp are called onlays. Restorations which cover the entire tooth are called crowns (commonly known as caps). Whenever possible, it is better to place an inlay or an onlay on a tooth because it requires less tooth reduction that needed for a crown. Placing a crown on a tooth requires removing more tooth structure than an inlay or onlay, which increases the chances of the tooth requiring a root canal in the future.

Cavities, fractures and dental procedures are all traumatic and irritating to the pulpal tissues (nerves and blood vessels) of our teeth. The pulpal tissues become swollen and sensitive in response to trauma, and can swell up to the point where their blood supply is cut off since the pulp is confined within the inside of the tooth. Once the pulpal tissue has died, a root canal is required to keep the tooth. This is why a tooth should always be restored as soon as possible with the smallest restoration possible, and is the the backbone of the Minimally Invasive Dentistry philosophy. If a tooth has already had a root canal, is severely broken down, or has an existing crown which is failing, then a crown needs to be placed on it. The CEREC machine is a valuable piece of equipment when it comes to Minimally Invasive Dentistry and reducing pulpal trauma.

http://www.losgatosdentalgroup.com/cerec.htm

Houston cosmetic dentists frequently recommend inlays or onlays to restore damage to the chewing surfaces of back teeth. Both inlays and onlays are pre-formed from a mold so they'll fit your tooth precisely. But what's the difference between the two?
Inlays fit within the grooves between the cusps of your tooth. Onlays fit within the grooves and wrap up and over the cusp tips, so they cover more of the tooth's surface. Your Houston cosmetic dentist will decide which is most appropriate for you, based on the amount of tooth structure lost to wear or decay.

http://www.softdental.com/Houston_Dentist_Article_inlays_and_onlays.html

The difference between a filling and indirect restorations is the material out of which they are made. The materials which fillings are made of can easily be placed in a tooth and harden up quickly with no ill effects to the tooth. Fillings are relatively easy and quick to place, and are a good choice for teeth in need of a small restoration, but are nowhere near as strong as an indirect-placement restoration. Crowns, inlays and onlays are made of gold and/or porcelain which both require extremely high temperatures to melt and shape which is why they are made on precise models of your teeth and not in your mouth. Gold and porcelain restorations are many times stronger and more durable than fillings, which is why they are the ideal choice for teeth which are in need of larger restorations.

In our office, we place composite resin fillings instead of amalgam. Composite resin is a type of reinforced acrylic which is manufactured in different shades to match teeth of different color. Composite resin is placed into your tooth as a thick paste which can be shaped and sculpted as needed. When we are done shaping the composite resin a bright blue light is directed at it which causes the composite resin to turn hard. Composite resin fillings are fully hardened after the blue light has been placed on them. Unlike amalgam fillings, composite resin fillings do not have minimum size requirements, and it is easy to detect early cavities on the edges of the filling because the cavity is easily seen against a white background. Composite resin fillings are mercury free and have not been attributed to any deleterious medical effects.

Fillings are classified by how many surfaces of the tooth they involve. Teeth have five surfaces- the chewing surface, cheek side, tongue side and the front and back sides where dental floss is used. The simplest filling is a one-surface filling and is used when a tooth has a cavity on the chewing surface. If the cavity is in between teeth, or extends to the cheek or tongue side of the tooth, a two or three surface filling may be required. As a general rule, if a the width of a composite resin filling will be more than one-third the width of the tooth, or if more than two surfaces are involved, a porcelain restoration is a better choice. Composite resin fillings are an excellent restorations when used in the right situations, but are not the always the best choice. In our practice we take pictures of your teeth and existing dental work using a small camera that goes inside your mouth to help you make the right decision when it comes to restoring your teeth.

http://www.losgatosdentalgroup.com/fillings.htm

The dental inlay or onlay is sometimes used as an alternative to a crown. This option is determined by the amount of tooth structure left after decay or trauma has occurred. Sometimes a plastic filling will not suffice to replace missing tooth structure with consideration to material strength and adjacent tooth contact form.

The difference between an inlay and an onlay is self-evident: an inlay fills in a tooth and an onlay is placed on, or covers a tooth. Both are made in a dental laboratory through an impression that we take in the office. Inlays and onlays can be made of Plastic or Gold.

While plastic is more aesthetically pleasing, gold offers the advantages of strength and biocompatability. The choice of plastic or gold is made with our patients on a case by case basis.

Before Plastic Inlay	Before Gold Inlay
After Plastic Inlay	After Gold Inlay

http://www.tischlerdental.com/html/inlays_onlays.html