Page 32 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability
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                                CHAPTER 3
implants placed in onlay grafts in the maxilla after a mean follow‐up of more than 9 years.57 To assess the peri‐implant health, they removed the screw‐retained reconstruction; 11% of the implants presented with a PD ≥ 5 mm despite more than 39% of the implants with BoP. There was no correlation between the registered BoP 39% and the bone loss, but the PD reflected the bone loss. Serino, Turri and Lang demonstrated differences in PD with or without the implant construction in place.58 The PD showed a high correlation with bone loss when the reconstruction was removed. The presence of the construction impeded the accuracy of the PD registration, and only in 37% of the sites, similar results were obtained with probing with or without the construction. They concluded that PD reflects the bony defect only when access for probing is ideal. However, full jaw prosthesis often present with overhang, which may lead to inaccurate probing and false‐positive diagnosis. In addition, the measurement error encountered with probing is higher around implants than around teeth and the type of implant may affect the absolute PD value.41,59
The aforementioned studies all suggest that the use of an absolute PD threshold to diagnose the soft tissue around implants should be performed with great caution. Based on the current evidence, the PD value alone cannot be considered a reliable indicator for defining peri‐implantitis.58 When actual bone loss is not correctly taken into account, due to the absence of a baseline radiograph, and when the PD is the only determining factor in the diagnosis, this may undoubtedly account for the high reported prevalence of peri‐implantitis in some studies. It is obvious that change in PD over time, once a physiological steady state in the soft tissue has been established, may be regarded as an indicator of disease activity. Huang and colleagues suggested that a baseline PD should be established as a basis for comparison over time because initial implant location may affect the PD.60 A recent systematic review concluded that the use of progressively deepening probing depth is more meaningful than using absolute PD values of ≥4or5mm.61
Bleeding on probing
Bleeding on probing is used in periodontal diagnosis. It is a poor predictor of disease progression, but the absence of BoP is a good predictor of future tissue stability.62 Lekholm and colleagues reported that neither deep pockets nor BoP was found to be accompanied by accelerated marginal bone loss.55 The probability
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