Page 147 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

THE LONG-TERM EFFECT OF ADAPTING THE VERTICAL POSITION OF IMPLANTS ON PERI-IMPLANT HEALTH
for a highly negative answer to the question. The total score of the questionnaire can range from 0 (maximally positive on all items) to 56 (maximally negative). The questionnaire was assessed before surgery as well as 3 and 60 months after connection of the prosthesis with the implant. The impact of the change was assessed by calculating the “effect size” with the use of the following formula: ((mean-OHIP before surgery) - (mean-OHIP three months after connection))/SD before surgery. As proposed by Cohen 1977, an “effect size” > 0.8 is interpreted as large, 0.6 is interpreted as moderate, and 0.2 is interpreted as small.
Statistical Analysis
Data analysis was performed in SPSS Statistics 26 (SPSS Inc., Chicago, IL, USA). Outcomes are reported with descriptive statistics (mean, standard deviation (SD), median, range) and visualized through boxplot representation. All analyses concern pair-wise comparisons within patients. For dichotomous variables, the McNemar test was used, and for continuous variables, paired t-tests were applied. The 95% confidence intervals (95% CI) are given to show the precision of an estimate of a certain effect. The sample size was calculated using an SAS Power and Sample size calculator for related samples based on an effect size of 1 mm mean bone level difference between test and control and a standard deviation of 0.60, with the level of significance set at 0.05 and β = 0.80. The effect estimation was based on findings published previously .14
An analysis of the measurement error for the continuous variable bone level between the observer S.V. and R.D. was performed by the use of a scatterplot representation and a paired-t-test. The random error, or duplicate measurement error (DME), was calculated with the formula SD/√2.
Incidence of peri-implantitis is based on the definition of peri-implantitis according to the 2017 Consensus report of the World Workshop on the classification of Periodontal and Peri-Implant Diseases and Conditions.15 Implant success was defined in two ways: firstly, as 2 mm bone loss in combination with bleeding on probing as proposed by Klinge et al.,16 and secondly, as 1 mm additional bone loss after initial bone remodeling.
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