Fillings · Patient education
Filling, inlay, onlay or crown: how much tooth is covered?
Understand direct repairs, custom-made inserts and partial or full coverage before comparing estimates.
Clinically reviewed by Dr. Ghazala Zaid · 2026-09-13
The short answer
These terms describe different ways of restoring a tooth. A direct filling is shaped in the tooth; an inlay or onlay is made separately and fitted. An onlay covers one or more chewing cusps, while a full crown covers the prepared visible tooth. More coverage is not automatically better.
- 1. Direct filling
- 2. Inlay
- 3. Onlay
- 4. Full crown
Labels run left to right. AI-generated teaching illustration. Gold colour marks restoration coverage, not a recommended material. Filling versus inlay also differs in fabrication, which this image cannot show. Simplified shapes, not to scale.
Compare at a glance
General differences, not a recommendation for your own treatment.
| What matters | Direct filling | Inlay | Onlay | Full crown |
|---|---|---|---|---|
| How it is made | Material shaped directly in the tooth | Custom restoration made outside the mouth | Custom restoration made outside the mouth | Custom restoration made outside the mouth |
| Coverage concept | Repairs the prepared area; extent varies | Usually fits within the chewing cusps | Covers one or more chewing cusps | Covers the prepared visible tooth |
| Key planning question | Can a direct repair adequately restore this tooth? | Why choose an insert rather than a direct filling? | Which cusps need coverage, and why? | Why is full coverage needed rather than partial coverage? |
| Estimate question | Which surfaces and material are included? | Are fabrication and fitting included? | Are fabrication and fitting included? | Are buildup, temporary crown and fitting included? |
Swipe the table sideways to compare all options.
Coverage and material are separate decisions
An onlay is a design, not a material name. Inlays and onlays may use ceramic, composite or metal alloys. Ask the dentist to identify both the shape of the restoration and its material. Terms such as overlay or partial crown can be used differently, so a drawing of your planned coverage can be useful.
The illustration uses gold colour to show the repaired area. It does not recommend gold or show how each restoration is made. A picture cannot establish how much of your own tooth needs treatment.
Compare the complete plan
Ask for the reason behind the proposed coverage, the alternatives and what would change the recommendation after examination. Request a written sequence of preparation, fabrication and fitting, and clarify whether a temporary restoration is planned.
When comparing estimates, ask the same questions for each plan: which appointments are included, who makes the restoration, what review is provided and what costs may be separate. This page does not confirm that the clinic offers every option.
Take these questions to your dentist
Use this as a conversation checklist. You do not need to choose a treatment before your assessment.
- Can you show which part of my tooth needs repairing?
- Why would a direct filling or partial coverage be unsuitable?
- Which material and fabrication method are proposed?
- What is included in the estimate and follow-up?
Common questions
Is an onlay always better than a filling?
No. Ask why the proposed design suits the tooth; these are not quality grades.
Does a custom-made restoration always need two visits?
Ask about the actual workflow and appointments. The term custom-made alone does not establish the schedule.
Sources and review
Sources inform the general explanations above. They do not endorse this clinic or replace an individual examination. Material manufacturers are referenced for product identification, not independent claims of superiority.
Understand what makes sense for you.
Bring your questions to Cedarbrae Dental Center in Scarborough. We can assess your needs and discuss appropriate options. An appointment request is not a confirmed booking.