Multi-unit abutment: Also known as screw retention abutment, it is especially suitable for the restoration of multiple missing teeth. The composite abutment can transfer the plane of the repair interface from the bone surface to the soft tissue layer, and can adapt to various superstructures. In terms of structure, the composite abutment is a "two-stage" abutment.
Difference between Multi-unit abutment and ordinary abutment
(1) Different retention: The composite abutment adopts screw retention, and the crown is connected with the composite abutment by screws, which is more suitable for the restoration of continuous missing teeth; Ordinary abutment adopts adhesive retention, and the crown and abutment are connected by adhesive, which is more suitable for the restoration of a single tooth.
(2) The shape is different: the upper part of the ordinary abutment is used for bonding with the crown, and the height is higher, while the upper part of the multi-unit abutment is shorter, and the internal thread can be seen.
(3) The use is different: the upper part of the ordinary abutment can be ground and modified, but the multi-unit abutment part cannot be ground and modified.
Classification of Multi-unit Abutments
Based on the relationship between the abutment and the long axis of the implant, they are classified as straight Multi-unit abutments (0° composite abutments) and angled composite abutments. Generally, the system-angled multi-unit abutments are further divided into two types: 15°/17° and 30°.
Selection of Multi-unit abutment
(1) In cases of immediate weight-bearing, choose a composite abutment with appropriate gingival height directly. Depending on the direction of implant implantation, choose the corresponding straight composite abutment or angled composite abutment, and try to make the upper part of the composite abutment face in one direction (preferably facing the opposite jaw).
(2) If it is a case of delayed weight-bearing, when selecting a healing abutment in the second phase, the diameter of the healing abutment, the diameter of the gingival and composite abutments, and the gingival penetration should be considered as consistent as possible. At least ensure consistent diameters in order to select and install suitable composite abutments.
(3) You can use a measuring ruler to confirm the height of the gingival penetration. The front tooth area should consider aesthetics and avoid any metal leakage. It is recommended to install the shoulder position of the composite abutment 0.5mm/1mm below the gingiva. For the rear tooth area, it is convenient to install and consider flattening the gingiva. The angle composite abutment should consider the buccal and lingual positions.
