Page 176 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

CHAPTER 7
Table 4: Implant distribution at t2 according to mean bone level and mean probing pocket depth; numbers between brackets show implants with bleeding on probing
Probing Pocket Depth (mm)
Mean Bone Level (mm)
< 0.5
0.5 - 0.99
1.00 - 1.49
1.50 - 1.99
2.00 - 2.49
≥ 2.5
total
≤1 0 0 0 0 0 0
0
0
9 (3) 32 (15) 21 (12) 9 (2) 3 (1) 74 (33)
1.1 - 2.0 2.1 - 3.0 3.1 - 4.0 4.1 - 5.0
0 0 1 (1) 0 0 0 1 (0) 0 > 5.0 1 (0) 2 (1) 0 0 0 0 Total 50 (19) 13 (8) 5 (2) 4 (3) 2 (1) 0
■ DISCUSSION
8 (3) 23 (9) 12 (6) 6 (1)
1 (0) 7 (4) 3 (3) 0
0 1 (1) 2 (0) 2 (1)
0 4 (3) 0
This prospective clinical split-mouth study evaluated the (long-term) effect of a microthreaded neck design and an internal abutment connection on peri-implant bone stability and peri-implant health in patients treated with an implant-supported overdenture on four implants in the maxilla. To minimize confounding factors, all study implants were similar but for one specific design factor, namely the internal versus external connection and microthreaded versus nonmicrothreaded neck design. Besides controlling the confounding factors, the split-mouth design corrects for inter-individual variability from the estimates of the treatment effect.14
The present study shows an implant survival of 95.9%, which is in accordance with earlier published RCTs and systematic reviews.3,4,15 All implant failures were early failures during healing and possibly caused by overloading of the nonsplinted implants. It should be stressed that implants were provisionally loaded. The abutments plus healing caps were located above the mucosal level and despite soft relining and regular check-ups overload during healing cannot be excluded. For future studies immobilization of the implants by splinting or lower prosthetic components are advised to overcome the limitation in this study protocol. One may suggest the use of healing abutments at mucosal level to avoid premature loading but this was not possible because in the context of controlling experimental confounders, the use of final abutments was advocated.
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