The primary objective of this study was the assessment of the peri-implant bone situation in immediate implants over a long-term period up to 10 years and to compare it to the situation found in matched non-immediate implants because there are no similar studies published. The hypothesis was that both the immediate implantation and the implantation after a healing period using the Frialit 2 implant system lead to similar results.

The uneven number of patients is due to the inclusion criteria. All patients that could be matched and were eligible for radiographic assessment were selected for evaluation.

This study evaluates implants in the every region of the human jaw. Due to the matching of every implant with an implant following the criteria set by the author, both implant groups remain comparable [9].

For the inclusion to this study, radiographs of the patients’ implants had to be present for either the time of insertion or the day patients received their definite restorations. For the time after prosthetic treatment, radiographs were taken whenever indicated or for other treatments in order to keep the exposure time to radiation as small as possible.

Due to the use of a strict and reliable measurement protocol [6–8] and the direct plotting of the found values for the bone defects, errors could be identified and reduced to a minimum. The anomalies found mainly occurred due to transcription errors while importing the data from the evaluation forms into the SAS JMP program. For outliers that could not be explained that way, the respective radiograph was reassessed and the measurement step was carried out again and the values corrected whenever needed. The different numbers of radiographs at the time of insertion in both groups are explainable by different reasons. Some radiographs even though acceptable for clinical use could not be assessed in this study either because of overlapping effects from structures adjacent to the implant or if the most apical part of the implant itself was not detectable on the radiographs the radiograph could not be assessed. In order to keep the exposure to radiation as low as possible, radiographs that provided the clinically relevant information were not repeated even though they could not be included in this study.