Understanding Dental Abutments

1. Stock abutment

• Has a specific shape, height, and angle.
• Suitable for most clinical situations.
• Ideal for cases where the space between the missing teeth allows sufficient occlusal space (adhesive-retained abutments generally require a minimum of 6 millimeters, while screw-retained abutments require a minimum of 4 millimeters of space), the difference between the implant and the restoration angle is within 15 degrees, and the implant depth is suitable.

2.  Customized abutment

• Can be adjusted based on the space between the missing teeth and the direction of the implant.

1. cement-retained abutment

• The crown is cemented to the abutment with an adhesive.
• To prevent the adhesive from entering the gingival sulcus, the connection between the implant and the abutment should be elevated to within 0.5 millimeters of the gingival margin.
• If removal of the crown is necessary, drill a hole at the appropriate location on the crown surface and remove the abutment screw.

2. Screw-retained abutment

• The restoration is screw-retained directly to the implant or abutment.
• Adjustment and maintenance of the restoration can be performed by simply removing the screws.

1. Straight Abutment

• The direction of the abutment is aligned with the direction of the fixation screw.

2. Angled abutment

• Primarily used when the implant direction is off.
• Especially useful for maxillary anterior restorations.
• Typically used with adhesive fixation and allows angle adjustment in the range of 15 to 25 degrees.

1. Titanium alloy abutment

• Significantly higher strength than pure industrial titanium.
• Provides increased tensile strength and fracture resistance.
• Silver gray, commonly used for posterior tooth implant restorations.

2. Zirconia Abutment

• An esthetic alternative to traditional titanium abutments.
• Manufactured using CAD/CAM processes to ensure a high-quality surface finish and excellent mechanical strength.
• Available as full zirconia abutments and titanium base-zirconia abutments.

1. Bar Attachment Abutment

The bar attachment abutment is a type of attachment used to stabilize and support overdentures. It is a bar framework that connects multiple implants and provides increased stability and retention for removable prosthetic restorations.

The Locator Abutment is a popular attachment system used in implant dentistry. It consists of a male abutment on the implant and a corresponding female abutment in the prosthesis. This type of abutment provides secure retention while allowing for easy insertion and removal of the prosthesis.

It is mainly divided into external connection and internal connection. Internal connection can be further categorized into conical connection method and end-to-end docking method. At present, the internal connection method is the mainstream connection method for implant abutment.

External Connection refers to the contact between the abutment and the top surface of the implant. Based on geometric shapes, it includes external hexagonal and external octagonal connections, among others.

Compared to internal connections, external connections have drawbacks such as insufficient resistance to lateral forces and the risk of screw loosening, especially when used with narrow-diameter implants.

Internal Connection refers to the absence of protrusions on the coronal side of the implant platform, with a design that incorporates a deep concave structure within the implant.

The abutment penetrates the implant and relies on the design to provide resistance to self-rotation, abutment stabilization, anti-shearing, and precise positioning.

Internal connection is currently the dominant method of implant-abutment connection.

When the abutment/implant junction shifts from the implant edge to the center, resulting in the abutment diameter being smaller than the implant platform diameter, this internal connection method is known as platform switching.

Current research suggests that platform switching involves the migration of the implant-abutment interface toward the center, shifting bacteria and micromotion away from the bone-implant interface.

This shift is believed to reduce marginal bone resorption by moving these factors away from the osseointegration zone.

The Morse taper connection is a type of internal connection for abutments and implants that relies primarily on the mechanical frictional retention force generated by the taper structure. Its key features include:

Excellent microbial sealing capability, reducing micro gaps at the implant-abutment interface and preventing microbial accumulation at the interface.

High mechanical stability, which reduces abutment micro-movement and minimizes the risk of screw and abutment loosening.