A pivot tooth is a dental prosthesis designed jointly by the dentist and dental technician. It replaces a tooth whose root is in good enough condition to accommodate a rod, generally metallic, itself supporting an upper part called the crown.

This pivot tooth can be produced in two ways:

– In a single block glued in the hollows of the root.

– In two parts: the stem, then the ceramic crown. This technique is more recommended since the system better absorbs the mechanical stresses of chewing. 

A pivot tooth is possible when the natural tooth is so damaged that its visible part, the crown, is no longer constructible with a simple inlay or a metal filling. It is therefore necessary to add an anchor on which the crown will rest. The main indications of a pivot tooth, and a crown in general, are¹ :

• The trauma or fracture too large for any other reconstruction
• Advanced decay
• Significant tooth wear
• Severe dyschromia
• Severe malposition of the tooth.

Crowns are fixed prostheses that will cover the upper part of the tooth to restore their original morphology. They can be performed on the remaining dental tissue (thanks to a preparation) or fixed to a metallic or ceramic “prosthetic stump”: the pivot, also called the post. In the latter case, the crown is not glued, but sealed to a pivot slipped into the root of the tooth.

There are several types of crowns depending on the indication, but also according to the aesthetic and economic gradient offered to the person requiring the fitting of a crown.

Cast crowns (CC). Made by casting a molten alloy, they are certainly the least aesthetic and the least expensive.

Mixed crowns. These crowns combine 2 materials: an alloy and a ceramic. In vestibular encrusted crowns (VIC), the vestibular surface is covered with a ceramic. In metal-ceramic crowns, the ceramic completely covers the tooth surface. They are more aesthetic and obviously more expensive.

All-ceramic crowns. As their name suggests, these crowns are made entirely of ceramic, which is also very resistant. They are the most aesthetic and the most expensive.

The aesthetic criterion is not the only criterion, however: the crown must meet the needs of the oral cavity. Metal reconstructions are currently widely used despite their unsightly side: the mechanical properties and the ease of production in the laboratory speak for them! In the case of the pivot tooth, this crown is necessarily associated with a prosthetic false stump fixed, screwed or placed in the root.

When a tooth is too damaged, following a major decay or a powerful shock, devitalization is often carried out to stop the progression of the infection and remove any sensitivity of the tooth. This basically involves removing the nerves and blood vessels from the infected tooth and plugging the canals.

If the tooth is only partially damaged, file it to obtain a regular shape, take its impression and cast a metal or ceramic-metal prosthesis.

But if the tooth is too structurally damaged, it is necessary to anchor one or two pivots in the root to stabilize the future crown. We speak of “inlay-core” to designate this false stump sealed with cement.

Two sessions are necessary to perform the operation.

Avoid when possible. The decision to crown the tooth with a root anchor is to be taken after careful consideration.². The realization of the anchors is not without risks and involves a loss of substance which weakens the tooth. Indeed, contrary to a stubborn belief, it is not the devitalization of the tooth that would make it more fragile.^{3 4}, but the loss of substance induced by decay or by surgical mutilation. When possible, the practitioner should therefore turn to reconstruction of the tooth devitalized by a less mutilating crown and strive for maximum tissue savings.

The stall of the pivot tooth. The loss of tissue linked to the anchoring of the pivots can lead to a reduced resistance to the stresses linked to the occlusion, increasing the risk of fracture. When this happens, the tooth comes off. While waiting for the appointment at the dentist (imperative!), it is advisable to replace it delicately after having taken care to clean the root (a mouthwash and a dental jet are adequate) and the pivot rod. It will nevertheless have to be removed during meals to avoid swallowing it: it is unlikely to support the tensions of chewing.  

If your root has remained intact, you will be assigned a new pivot.  

On the other hand, if your root is infected or fractured, it will be necessary to think about the dental implant or the bridge.