When a tooth has lost too much structure — through extensive decay, an old filling that has failed, a fracture, or after root canal treatment — a direct filling stops being the right choice. Not because it will not «hold», but because it does not give the tooth back the strength it needs to chew.
From there, two routes open up.
The principle that guides everything
One principle steers the choice more than any other: preserve as much healthy tissue as possible. Every millimetre of natural tooth that remains is structure that will not have to be replaced. That is why, for an equivalent result, the least invasive option is always preferred.
The inlay: when enough tooth remains
An inlay is a restoration built outside the mouth — in ceramic or composite, from an impression, today often digital with an intraoral scanner — and then bonded into the prepared cavity.
It is chosen when the tooth walls are still sound and the loss of structure is significant but contained. Compared with a large direct filling it offers more precise contact points and anatomy; compared with a crown, it requires a far more conservative preparation.
The crown: when the tooth needs to be wrapped
A crown covers the tooth all the way round. It becomes the indicated choice when the remaining structure is limited and the walls would not withstand chewing forces: after major fractures, on heavily compromised teeth, or on posterior root-treated teeth, which are more brittle and benefit from protection that «wraps» them.
It is more invasive than an inlay, but in those situations it is what allows the tooth to last.
How we decide
The choice is made after removing the decay and seeing the real situation: before that moment only a hypothesis is possible. We assess how much healthy tissue remains, where the margins sit relative to the gum, whether the tooth is vital, what the bite is like, and whether there are clenching or bruxism habits that load the restoration.
How long it lasts
No restoration is forever. Longevity depends on the quality of the marginal seal, home hygiene, chewing load and periodic check-ups. A well-made restoration on a clean, regularly monitored tooth lasts many years: the same restoration in a mouth with plaque and inflammation lasts far less.
Before the restoration, the foundation
An inlay or a crown placed on inflamed gums or over uncontrolled decay is work destined to fail early. First the foundation is sorted — hygiene, periodontal health, any necessary therapy — then the tooth is rebuilt.
Sources
- Italian Ministry of Health — Dental health — prevention, periodic check-ups and oral health.
- FDI World Dental Federation — international reference on oral health and dental practice.
- WHO — Oral health fact sheet — untreated caries as the most widespread oral condition.