Effects of a New Implant Abutment Design on Peri-Implant Soft Tissues
The purpose of this study was to assess the effects of a modified implant abutment design on peri-implant soft and hard tissues in dogs. Three months after extraction of mandibular premolar teeth, 3 dental implants were placed in each side of the jaw using a 1-stage approach. Implants on one side of the mandible received standard abutments (control), and implants on the contralateral side received modified, patented, grooved abutments (test). Two months after implant placement, animals were euthanized and specimens were prepared for histologic and histomorphometric assessment. The linear distance (in micrometers) was measured from the implant shoulder (IS) to the following landmarks: gingival margin (GM; distance IS-GM), most apical position of the junctional epithelium (JE; distance IS-JE), and bone crest (BC; distance IS-BC). Percent of bone-to-implant contact was also measured. Histologic assessment revealed that all implants were osseointegrated and that interimplant gingival fibers between test abutments appeared to be more numerous and organized than control abutments. The IS-GM and IS-JE distances in test implants were greater than the corresponding distances in control implants (P = .024 and P = .015, respectively), whereas crestal bone loss (IS-BC) was greater for control implants than test implants (P = .037). There were no differences between control and test implants in bone-to-implant contact (P = .69), which averaged close to 50%. These results suggest that the modified groove design incorporated in standard abutments confers both soft and hard tissue benefits.
Figure1. Study timeline. Figure 2. Schematic drawing illustrating the landmarks used for histomorphometric measurements. IS indicates implant shoulder, the abutment/fixture borderline; GM, gingival margin, the marginal portion of the peri-implant mucosa; JE, junctional epithelium, the most apical termination of the JE; BC, bone crest, the marginal level of bone-to-implant contact. Figure 3. Light microscopic view of a representative jaw specimen demonstrating osseointegrated implants with test abutments. Note the apical end of the JE positioned at or coronal to the first abutment surface groove. (Stevenel blue and Van Gieson picro fuchsin; magnification ×10). Figure 4. (a) Left, transversely sectioned implant (transmission light). Note the intimate bone to implant contact. (b) Right, the same section (polarized light). Note the diverse orientation of the lamellar bone collagen fibers (different color and brightness) (Stevenel blue and Van Gieson picro fuchsin; magnification ×25). Figure 5. Transverse section of a test abutment demonstrating dense circular fibers surrounding the grooved abutment (Stevenel blue and Van Gieson picro fuchsin; magnification ×25). Figure 6. At a higher magnification of the test abutment specimen shown in Figure 5, it is possible to note the collagen fibers (stained light green) and the associated fibroblastic cells (arrows) near the abutment surface (Stevenel blue and Van Gieson picro fuchsin; magnification ×200). Figure 7. Light microscopic view of the peri-implant tissues around (a) a test and (b) a control abutment in the same animal. The specimens demonstrate differences in density and orientation of the gingival connective tissue fibers: dense connective tissue fibers are oriented perpendicular to the test abutment surface (a), and less dense fibers are oriented parallel to the control abutment surface (b). Apical migration of the epithelium, resulting in a long JE is evident on the control abutment surface (b). The apical end of the JE (black arrows) is located closer to the implant-abutment junction in the control abutment (Stevenel blue and Van Gieson picro fuchsin; magnification ×25).
Contributor Notes