Dental inlays and onlays offer an excellent alternative to “direct” amalgam or composite fillings to restore teeth that have sustained some damage, but not enough to require a full coverage crown. While “direct” fillings such as dental amalgam and composite fillings are placed immediately after the decay or damage is removed and the tooth is prepared, inlays and onlays are known as “indirect” fillings. This means that they are fabricated outside of the mouth prior to final bonding or cementation.

While in the past, many inlays and onlays were caste from gold; today’s dental inlays and onlays are typically custom made of either the highest grade of dental porcelain or composite resins. In addition to providing an exact match to the color of tooth for a cosmetically pleasing result, inlays and onlays have the distinct advantages of being more durable than other fillings, preserving more underlying tooth structure and actually strengthening the tooth so that it can bear up to 50 to 75 percent more chewing forces.

Inlays and onlays only differ from each other in the amount of tooth structure they cover. An inlay is fabricated when the replacement of tooth structure does not require coverage of any cusp tips. If the damage from decay or injury is more extensive and involves more of the tooth’s chewing surface, including one or more cusp tips, an onlay is required.

Both inlays and onlays are fabricated outside of the mouth based upon the exact specifications provided by an impression of the prepared tooth. The final inlay or onlay is then custom made by either a dental laboratory or in-office with a same day system.

If a tooth has been significantly damaged by decay or injury or if it is too misshapen, undersized, or darkly stained to be restored with fillings, dental bonding or veneers, a full coverage restoration is typically required. Known as a dental crown or “cap,” a full coverage restoration is custom designed and fabricated by the dentist to fit over the damaged tooth to recreate a healthy and natural appearance and to re-establish the function of the tooth. Beyond restoring the form and function of the tooth, a dental crown serves to strengthen and preserve the underlying tooth so that with proper care it can be maintained for many years.

Dental crowns are typically recommended as the restoration of choice when a tooth has undergone a root canal procedure. They are also used to cover the abutment teeth next to an edentulous space to provide support for a fixed bridge and are used for the restoration of dental implants to serve as a permanent replacement for a lost or missing tooth.

Crowns can be fabricated from a variety of materials including porcelain or dental ceramics, porcelain fused to metal, composite resin and metal alloys. Which type of crown is fabricated depends upon the aesthetic and functional requirements of the case, patient preferences, and budget.

How are dental crowns fabricated?

Tooth preparation and crown fabrication is a multistep process:

1. The dentist prepares the tooth by removing the outer layers of the tooth as well as any damaged tooth structure. If there is not enough tooth structure remaining, the core of the tooth can be built up with restorative materials as needed to provide sufficient retention for a crown.
2. A detailed impression is taken and a model of the prepared tooth is constructed.
3. A custom crown is fabricated based upon the exact specifications of the model.
4. If the crown is not to be placed the same day, a temporary crown is placed to cover and protect the prepared tooth as well as maintain its appearance.
5. The final crown is checked for fit and appearance. Once any final adjustments are made, the crown is cemented or bonded into place.

With proper care and maintenance, a dental crown can last for many years.

With advances in dental materials and science, restorative materials that are aesthetically pleasing as well as strong and durable are widely available for the filling and repair of teeth that have been affected by tooth decay or dental injuries.

Composite fillings, which are frequently referred to as either “tooth colored fillings” or “white fillings,” are a combination of biocompatible resins and finely ground, glass-like filler materials. Composite fillings, which are manufactured in a complete range of natural looking shades, provide a more cosmetically pleasing alternative to traditional “silver” fillings. Often used to fill a tooth by replacing tooth structure that is missing due to injury or decay, dental composites can also be placed to modify a tooth’s color or shape to dramatically improve its appearance as well as repair dental defects and close gaps between the teeth.

The composite systems used by dentists today integrate the highest quality of microfill particles and resin materials to produce restorations that can withstand the forces generated by all manner of oral function, while achieving attractive, natural looking and long-lasting results. Composite restorations are adhered to the underlying tooth structure through a bonding process, which also serves to seal and strengthen the tooth. Once a composite restoration is placed and is “set” or “cured”, the dentist can refine its shape as well as smooth and polish it to maximize patient comfort. This also helps to prevent the restoration from staining and to avoid premature wear. Besides providing a pleasing match to your natural tooth color, a composite restoration has other advantages over other types of restorations. Composite fillings do not require the removal of as much tooth structure to facilitate placement, nor are they subject to expansion or contraction with temperature changes as is the case with dental amalgams. However, the one drawback is that composite restorations may be more vulnerable to wear and stains over time and can require replacement down the road.

For many years, amalgam fillings, more commonly referred to as “silver fillings,” have represented the standard of care in rebuilding the form and function of a tooth that has been treated for dental decay. Composed of a combination of metals that include silver, tin, mercury and copper, dental amalgam has both the strength to withstand the heavy forces generated during chewing as well as the durability to retain its integrity over time. Although not as aesthetically pleasing as other types of restorations, amalgam fillings are less likely than some other types of fillings to break or wear down over time.

While dental amalgam contains elemental mercury, based on extensive studies and thorough reviews of scientific evidence, the American Dental Association (ADA), The Center for Disease Control and Prevention (CDC), the FDA, and the World Health Organization have all stated that amalgam is a safe and effective dental restoration that does not pose a risk to health. However, individuals with allergies or sensitivities to the metals in dental amalgam are advised to pursue other restorative options with their dentists.