Personalized implant abutments and their selection

1. Structural characteristics of the abutment
A dental implant consists of three parts: the implant, the abutment and the crown.

The implant abutment is the key connection between the implant and the upper restorative structure and is generally divided into three parts: the implant connection part, the gingival penetration part and the restorative retention part.
The personalized abutment is designed according to the characteristics of the patient's oral cavity, which is more in line with the concept of "personalized treatment" than the traditional finished abutment, and is able to match the internal mechanical structure of the implant to the greatest extent. The cervical edge of the abutment is closer to the natural tooth and is more conducive to the gingival profile and gingival papilla formation. In addition, some scholars have concluded that personalized abutments can effectively reduce the occurrence of food impaction after implant restoration. Personalized abutments are generally classified as malleable abutments, castable abutments and CAD/CAM machined abutments.

2. Unique advantages of personalized abutments over other abutments

Optimal abutment gingival contour can be created to support long-term aesthetics
Margins can be set at the ideal level to allow for easy and safe removal of excess adhesive
The abutment design provides optimal support and retention for the final restoration

Three, the principle of choosing abutment

(1) Principle of implant long axis compensation

The ideal long axis of the implant should be parallel to the direction of occlusal stress to avoid the horizontal moment. In clinical work, we mainly use the proximodistal and buccolingual long axis of the adjacent teeth as a reference. If the implant long axis is consistent with the proximodistal and buccolingual long axes of the adjacent teeth or the difference is less than 15°, a straight abutment is selected and no abutment is needed to compensate for the implant long axis. On the contrary, an angled abutment is required to compensate for the implant length axis.

(2) Principle of gingival distance compensation

The gingival distance is equivalent to the vertical distance from the cervical platform of the implant to the contralateral tooth surface when the remaining teeth are interdigitated. The distance is the full height available to the abutment and the restoration above it. In clinical practice, when the gingival distance is greater than 5 mm, the choice of abutment is more varied and less restrictive, so there is no need for the abutment to compensate for the insufficient gingival distance. However, when the gingival distance is less than 5 mm, the bonding height of the bonding abutment is not guaranteed, and the clinical effect of screw-retained abutments and personalized one-piece crown abutments has been affirmed in the use of compensating for the insufficient gingival distance.

(3) Principle of peri-implant health

The mucosal closure of implant prostheses is weaker than that of natural teeth. The biocompatibility of the abutment material, the rationality of the abutment shape and margins, the patient's oral environment and hygiene habits directly affect the long-term health of implant prostheses. As far as the current material science is concerned, titanium and zirconia are the ideal abutment materials. The abutment shape needs to be conducive to the growth of the gingival papilla and the spillage of food residues. In the missing tooth areas with low aesthetic requirements, such as the posterior region, an abutment margin of 1 to 2 mm above the gingiva can be considered, which is conducive to the maintenance of the patient's oral hygiene and reduces the occurrence of biological complications.

(4) aesthetic principles

The influence of the abutment on the aesthetics is mainly due to the abutment material, abutment edge design, abutment screw hole location, and abutment profile curvature. The long axis of the implant lip tilt, insufficient implant depth, thin and receding gingiva may lead to metal translucency or exposure of the abutment, which can be considered to use personalized zirconia abutment; the aesthetic area can reasonably use temporary abutment to shape the gingival cuff with the final personalized abutment restoration to achieve the aesthetic effect; for the screw hole affecting the aesthetics can be considered to use bonded retention abutment or angular screw access abutment, placing the screw hole The angle of the screw hole opening can be adjusted from 0° to 25°, using specific abutment screws and ASC screwdrivers.