What is the recommended convergence angle of preparation for opposing walls?

The recommended convergence angle for opposing walls in dental preparation typically aims at ensuring adequate retention and resistance for the restoration. A convergence angle of 6 degrees is commonly accepted because it balances sufficient retention without compromising the material strength or risking damage to surrounding tooth structures.

When preparing teeth for prosthetic restorations, achieving the optimum convergence angle is crucial. A 6-degree angle allows for effective mechanical retention while also accommodating the cemento-enamel junction's natural contour. This angle is favorable for achieving a proper fit of the crown or restoration, minimizing undue stress on the tooth and ensuring long-lasting results.

Other angles, such as 3 degrees or wider angles like 9 degrees and 12 degrees, do not provide the same level of stability and retention. A narrower convergence (like 3 degrees) may lead to insufficient retention, making the restoration prone to dislodgement, while wider angles can compromise the restoration’s structural integrity and increase the risk of fracture or failure. Thus, the 6-degree convergence angle is recommended for optimal results in prosthetic dentistry.