It’s easiest to conceive of a partial crown as somewhere between a filling and a full-coverage crown, to be used in a tooth that is too damaged to fill but stable enough to not require a full crown. These partial crowns are commonly referred to as inlays and onlays. If you feel your molar with your tongue, you’ll notice that it’s got peaks and valleys. These peaks are called cusps. If a cusp needs to be restored, an onlay is used to cover over this cusp. When the chewing surface between the cusps needs repair, an inlay is fitted into that valley to restore its surface. Because full-coverage crowns are permanent and require that the natural tooth surface be altered, it’s important to carefully consider all the angles when choosing between this option and less-invasive inlays or onlays. You and your dentist should discuss and weigh all your options to ensure that you make the best decision.

Primary factors that affect the choice between partial and full-coverage crowns include:

1. The extent of damage to the tooth
2. Whether the natural tooth structure can be preserved
3. Location in the mouth and need for durability
4. Tooth function
5. Aesthetics
6. Budget and preference

The most important factor to consider when planning a restoration is the extent of damage the tooth has sustained. When a major portion of the tooth is damaged, due to decay, fracture, or a major filling, a crown is the optimal solution for maximal support and protection. When damage to the tooth is isolated to a smaller area of the tooth, inlays and onlays are used. Inlays are used within the cusps of the tooth, while onlays lay on and protect the cusps. With the goal of preserving as much of the natural tooth as possible, another consideration is whether a less invasive treatment is sufficient for each person’s needs. Because the tooth requires modification for a dental crown, meaning that a somewhat substantial portion of dental enamel is removed, an inlay or onlay is less invasive and allows for the preservation of more natural tooth material. If these conservative methods are sufficient to restore and protect the tooth, they’re preferred over full-coverage crowns.

When damage is significant and a sturdy restoration is needed, a crown will serve this need; by completely surrounding the tooth, they offer excellent protection, and its durable materials provide long-lasting support to weakened or severely compromised teeth. Dental crowns made of metals are especially protective, though patients might prefer porcelain crowns in more immediately visible areas of the mouth. In cases of milder or moderate dental damage, inlays or onlays might provide sufficient strength and protection while preserving the tooth structure. Aesthetic concerns are also taken into consideration, especially when the tooth or teeth being repaired are in the front of the mouth. While partial crowns are made from tooth-colored composite materials that closely match the natural tooth, the match isn’t exact, and inlays and onlays in this area may be visible when you smile or open your mouth. While advancements in dentistry help make inlays and onlays less visible with each passing moment, some patients still prefer the uniformity of full-coverage crowns in this “aesthetic zone.”

When a tooth withstands substantial chewing or biting force, a crown might be preferable to an inlay or onlay. These partial crowns work better on teeth with moderate chewing forces, where a full crown might be excessive. Of course, patient preference is the most important, and this includes convenience and budget considerations. The procedure for placing full-coverage crowns takes longer than the procedure for partial crowns, and crowns are also more expensive than inlays or onlays. When possible, inlays and onlays can be used when the budget is a concern, though crowns are often covered, at least in part, by some dental insurance policies. The best way to choose between partial and full-coverage crowns is to ask your dentist good questions, listen closely to their answers, and heed their treatment advice.

Related Article: What is a Full Coverage Crown?