Page 179 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

FOUR-IMPLANT-SUPPORTED OVERDENTURE TREATMENT IN THE MAXILLA
the effect of the microthreaded design because too few RCTs with low risk for bias were available. Moreover, they suggest that more RCTs with an adequate control for confounding factors for design are needed, because many studies have compared not only the microthread design but also other designs. To our knowledge, no more recent meta-analysis or RCTs other than the present study population could be found on PubMed when the search string “(microthread) AND (implant)” was used. The results from our paper confirm and strengthen the outcome described in the avail- able meta-analysis.
Today, only a few studies report on peri-implantitis incidence in patients with implant-supported overdentures in the maxilla. One study reported an incidence of 8.3% on patient level when restored with a maxillary overdenture on four implants in the anterior region and 4.5% on patient level for patients restored with a maxillary over- denture on six implants in the anterior region after 5 years of function.28 The same author published in a recent RCT an incidence of 17.2% for patients restored with a maxillary overdenture on four implants in the posterior region and 9.7% for patients restored with a maxillary overdenture on six implants in the posterior region after 5 years of function.15 They explained that the difference in incidence between anterior and posterior placed implants could be due to the fact that anterior placed implants are easier to maintain for the patient. The incidence of peri-implantitis in the present study is 0% on implant level, and thus 0% on patient level. However, the low incidence in the present study is based on another definition. The pre- sent paper based the incidence of peri-implantitis on the definition of peri-implantitis according to the 2017 Consensus report of the World Workshop on the Classification of Periodontal and Peri-Implant Dis- eases and Conditions.13 In this classification, bone loss above 3 mm is considered as threshold for disease. The papers by Slot and colleagues based the incidence of peri-implantitis on the consensus from the Seventh European Workshop on Periodontology,29 applying the threshold for marginal bone loss at ≥2 mm. If we apply the definition of the Seventh European Workshop on our study population and use a threshold of ≥2 mm in combination with bleeding on probing and/or suppuration, only one implant fulfilled this criteria resulting in an incidence of 1.4% on implant and on patient level.
An important limitation in this study could be the relatively short follow-up time. A recent study by Windael and colleagues suggests that bone loss at 2 years is
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