Ferrule effect has been defined as a 360-degree metal collar of the crown surrounding the parallel walls of the dentin extending coronally to the shoulder of the preparation.¹ The effect protects the tooth or implant from fracture by providing support to the crown. A visual for this effect is a wooden wine barrel that has metal bands encircling the body to give support when the barrel is full. (As defined in The Glossary of Prosthetic Terms)

Ferrule effect doesn’t guarantee that the tooth won’t fracture but does give assurance that it will reduce the risk. A ferrule should have a minimal height of 1.5 to 2mm.  

Advantages of having a Dental Ferrule:

• Resists functional lever forces and the lateral forces exerted during dowel insertion.
• Helps to reduce the wedging effect of a tapered dowel
• Preserves the root from external forces
• Helps to promote a hugging action between the tooth and artificial crown

 Various Types of Dental Ferrules:

• Uniform
• Non-Uniform
• Crown – when the overlying crown engages the tooth structure
• Core

Classifications:

• Category A – No anticipated risk – has 4 walls intact
• Category B – Low Risk – has 3 walls with distal and mesial missing
• Category C – Medium Risk
• Category D – High Risk – 2 walls mesial and distal, 2 adjacent walls or 1 wall with heavy lateral
• Category X – No Ferrule – absence of any walls

In implants a strong prosthetic connection is of utmost importance. Having a post with a strong internal and external connection helps to stack the deck for long-term implant success of your treatment. This simultaneous connection can occur with the patented Magic Post system. 

Internal Connection:

Resistant to lateral force

• Prevention of Screw Loosening
• Prevention of Crown Dislodgment 

Anti-rotation effect

Easy engagement method

External Connection:

Structural Durability (Ferrule Effect)

• Prevention of Fracture
• Prevention of Tearing

The design of an implant from the threads to the body connection makes an enormous difference for implant success. Minimally Invasive Implantology does just that and more.

1. Sorensen JA, Engelman MJ. Ferrule design and fracture resistance of endodontically treated teeth. J Prosthet Dent. 1990 May;63(5):529-36. doi: 10.1016/0022-3913(90)90070-s. PMID: 2187080.