Adjacent Dental Implants Classification Based on Restorative Design
There is controversy in the literature regarding the indicated retentive mechanism for implant-supported crowns. When adjacent implants are restored, the restoration can be screw retained, cement retained, or a combination of cement and screw retained. Adjacent implant-supported crowns can be restored as individual implant supported crowns or can be splinted. A classification system is proposed when adjacent implants are restored. The classification system describes currently available options to restore adjacent implants. Six types of prosthetic design options are proposed as Class I through Class VI. In Class I design, individual cement-retained crowns are made. In Class II, individual screw-retained crowns are fabricated. Class III involves fabrication of individual screw-retrievable/cement-retained crowns. Class IV prosthetic design involves splinted cement-retained implant crowns. Class V prosthetic design involves splinted screw-retained crowns, and Class VI involves splinted screw-retrievable/cement-retained implant supported crowns.
Figure 1. (a) Class I prosthetic design. Individual crowns are fabricated and cemented on the abutments. (b) Clinical situation where individual abutments were placed on adjacent implants. (c) Clinical situation where the definitive prosthesis was placed on adjacent implants comprising individual crowns cemented on the abutments. Figure 2. (a) Class II prosthetic design. Individual crowns are made that are screw retained on the implants. (b) Clinical situation were 2 adjacent individual screw-retained crowns were fabricated. (c) Definitive screw-retained crowns.
Figure 3. (a) Class III prosthetic design. Individual crowns are fabricated that are cement and screw retained. (b) Clinical situation where 2 adjacent implants were restored with 2 individual cement- and screw-retained crowns. Figure 4. (a) Class IV prosthetic design. The crowns are splinted together and cemented on the abutments. (b) Prosthetic design where 2 splinted crowns were fabricated to be cemented on the abutments. (c) Clinical situation; intraoral view with the definitive Type IV prosthesis cemented on the abutments.
Figure 5. (a) Class V prosthetic design. The crowns are splinted and screw retained on the implants. (b) Clinical example where 2 splinted screw-retained crowns were fabricated to restore 2 adjacent implants. adjacent implants. (c) Intraoral view, Type V prosthetic design. Figure 6. (a) Class VI prosthetic design. The crowns are splinted together and are designed to be cement- and screw-retained on the abutments. (b) Example of Type VI prosthesis, splinted crowns designed to be cement- and screw-retained on the abutments. (c) Type VI prosthesis; the splinted crowns are designed to be intraorally cemented and then screw retained to be easily retrievable.
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