Crowns, caps, emergency repairs, inlays, onlays, standard fillings... confused? No problem. Let’s break down the differences below so you’ll be clear about what your dentist is talking about next time you go.

STANDARD FILLINGS

A tooth filling is a material used to replace missing tooth structure caused by decay, breakage or trauma, like jigsaw pieces complete a puzzle or bricks make a wall. The filling recreates normal tooth shape, function, health and appearance for as long as possible. A completed tooth filling is often referred to as a restoration.

A standard filling is placed directly into a tooth and shaped by a dentist at a single appointment. In contrast to advanced fillings (see various types below), that require construction outside the mouth before being cemented or bonded into the the tooth by a dentist in one or more visits.

How is a filling made?

Traditionally amalgam has been used to create silver coloured fillings. These are cost-effective and long lasting, however not very aesthetic and eventually surrounding tooth structure will crack if the amalgam is not bonded, requiring further restoration. There have been health concerns raised about the mercury used in amalgam fillings, but there appears to be no clear evidence that once placed it is of any greater risk than general pollution and mercury levels are far lower than from other sources such as deep sea fish and car exhaust. No established correlation currently exists between health problems among dental industry workers and amalgam mercury exposure. Increasingly, amalgam is falling out of fashion for use as a tooth restorative material in favour of tooth-coloured materials.

Tooth coloured filling materials are far more popular today for appearance reasons and because they can be bonded to teeth, so less tooth loss occurs with filling placement than amalgam. Direct materials used in standard fillings include composite and glass-ionomer - various formulas of glass-resin mixes that set hard like plastic under blue light activation. These are relatively cost-effective to place, the appearance is generally good for a number of years, but they don’t tend to wear well over time, especially in back molar teeth replacing more than one surface or front teeth replacing more than two large surfaces. Composite materials will pick up stain over time, chip and wear away, but can be easily repaired, unlike indirect advanced materials.

CROWNS

What is a crown?

Crowns are custom tooth restorations made in once piece that fit over the whole tooth. Like a stubby holder fits over a beer bottle. Like a crown fits on the Queen’s head. A crown replaces tooth structure lost to decay or breakage. A crown is the strongest type of restoration and generally longest-lasting restoration for a tooth. It can also be the most expensive tooth restoration.

How is a crown made?

A crown is traditionally made in two visits from one or several specialty materials like gold, precious metal alloys, zirconia and porcelain. The process involves shaping and preparing the tooth; taking some impressions - with a moulding material or an optical scanner; wearing a temporary plastic crown for a couple of weeks while the final crown is made at a dental laboratory; then fitting the final crown with a dental cement at the second visit, making sure it has nice contacts with adjacent teeth and is comfortable to the bite.

Single visit crowns can now be constructed by dentists using a ceramic milling machine in certain situations. These generally don’t have as good a cosmetic finish as lab made crowns. They can be slightly cheaper than lab made crowns but if made well, are likely to last as long as a lab made one.

VENEERS

What is a veneer?

A dental veneer is similar to wood veneer panelling, where a thin layer of a quality material is placed over the top of another material, in this case tooth structure, to enhance its appearance, features and sometimes function.

How is a veneer made?

Dental veneer material is generally placed over the front or anterior teeth on the surfaces that can be seen. Veneers can be made from composite plastic material - like standard tooth coloured fillings, or porcelain - similar to crowns. The composite ones are generally cheaper, can be done in one visit and are less likely to need cutting of underlying tooth. However the aesthetics are rarely as good as porcelain veneers that usually do require irreversible tooth shaping and preparation over two or more visits, but often last longer.

CAPS

What is a dental cap?

Dental caps are the part of fillings that replace cusps - the pointy parts - of back molar teeth. They are technically called ‘cusp caps’. It is also used, slightly incorrectly, to refer to the replacement of the corner of a front tooth, correctly called the “incisal corner’. However the term is sometimes and incorrectly used as an alternative to a crown, or even a standard filling in a tooth which can create confusion. Remember, a crown is far more glamorous than a cap!

How is a dental cap made? 

Tooth caps are more likely to be made from direct filling materials such as tooth coloured composite plastics or metal amalgam. A tooth restoration including cusp caps or incisal corners made from ceramic or gold is more often called an inlay or an onlay (see below).

INLAYS

What is an inlay?

A dental inlay is a tooth filling that’s constructed outside the mouth, and glued in once it’s made. These restorations are usually long-lasting and more expensive than standard fillings. Inlays protect the tooth much better than a standard filling in many instances by helping to prevent cracks, they wear better and last much longer in demanding tooth use areas and generally look better too.

How is an inlay made?

Tooth inlays were traditionally made from gold alloys. A beautiful, long-lasting material, and sometimes a status symbol, gold is still used today in certain situations, such as a challenging bite, or appearance preferences by the future wearer - mouth bling anyone?

In recent times, inlays of almost any size and shape can be made easily from ceramic. Either milled by the dentist in a single visit, or by a lab in two visits. The ability to mill ceramic in one visit has made inlays much more popular as a restoration for back molar teeth especially, as they don’t take much longer to construct than a normal filling, but are generally a much better value for money restoration long-term.

ONLAY

What is an onlay?

An onlay is similar to an inlay in every way except it also includes cusp capping or incisal corners (see caps above). The difference between an onlay and a crown is like the difference between a tiara and a crown - a mini tooth crown that doesn’t require as much tooth shaping preparation as a full dental crown. This makes an onlay more like a veneer, except it’s designed more for function than just appearance. An onlay is more commonly used as a restoration for back or molar teeth, but can be placed anywhere.

An onlay is becoming the restoration of choice in many situations because it’s generally a great value-for-money, longer lasting, tooth conserving, restoration solution.

How is an onlay made?

Like an inlay, an onlay is traditionally made from gold alloy. These days gold is often used when there are bite concerns, or when someone wants gold for appearance reasons. Modern ceramic milling has made it predictable, convenient and cost-effective to make tooth-coloured onlays in one visit or two. Lab made onlays are often preferable when aesthetic details are super important such as for front teeth, or more complex cases involving multiple restorations.

EMERGENCY OR TEMPORARY REPAIRS

What is a temporary or emergency repair?

When part of a tooth breaks at an inconvenient time and the broken area is either rough to the tongue, causes pain or is unsightly, a dental professional can often do a quick repair using various types of filing materials to stabilise the situation until proper planning, time and money can be spent to create a more definitive, longer-lasting solution.

These are usually the cheapest restorations and dentists offer no guarantee as to how long they’ll last.

It’s often better and cheaper in the long-term to fix a tooth problem properly the first time if possible, but of course, there are exceptions to the rule! Your dental professional knows best about your specific situation.

Dr Christine May is a dentist, writer and founder of ViDe Virtual Dental Australia.

All health information in this article is of a general nature only and should not replace specific advice given to you by your own dentist in the lead up to or following a consultation.

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