Page 172 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

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42–83) at implant placement (t0). Two implants in two patients were excluded for further analysis, because placement of a study implant was not possible. Both implant sites required a 5-mm diameter implant to achieve sufficient primary stability (≥20 Ncm). Hence, 98 implants were available for follow-up after implant placement. Unfortunately by mistake, one patient received two E-MT and no E-NMT implant. However by respecting the intention-to-treat principle, the wrongly placed implant is analyzed according to the group it was originally assigned, resulting in the analysis of 24 I-MT, 25 I-NMT, 25 E-MT, and 24 E-NMT implants.
In all cases immediate provisional loading was possible and after a mean of 7.0 months (SD 2.05, range 3–11) after implant placement the final bar retained implant overdenture was placed. Twenty-four patients were available at the clinical and radiographic evaluation of t1. At t2, one patient could not attend the follow-up due to long-term illness and three patients did not respond to multiple invitations. Hence, 21 patients (82 implants) were available for follow-up at t2. Most visits planned at t2 were not carried out at 36 months but postponed due to the Covid-19 pandemic, resulting in a mean follow-up time of 45.5 months (SD 4.82, range 35–58) after implant placement.
Mean bone level, mean bone loss, and peri-implant health
Four implants (2x E-NMT, 1x E-MT, 1x I-NMT ) in three patients failed during the period of osseointegration, resulting in a survival of 95.9% on implant level. However, all failed implants were successfully rep- laced with the same type of implant after 3 months of healing and were included in further analysis.
The applied test for the inter examiner agreement on the measurement of the variable bone level resulted in a paired samples correlation ranging between 0.937 and 0.976 for the three observers. The random measurement error for this variable ranged between 0.09 and 0.16. Details of mean bone level, SD, median, and range per study implant at different time intervals is provided in Table 1. The mean bone loss for all implants between t0 and t1 was 0.39 mm (SD 0.62, range 0.00 - 3.48). The mean additional bone loss between t1 and t2 was 0.04 mm (SD 0.54, range -1.80 - 1.63). The negative number in the range is indicative for bone gain between t1 and t2. The bone loss between the different time points per implant type is giveninTable2.Thelinearmixed-modelanalysis(Table3)withmean bone level
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