The decision to make an implant impression is often based on the results of various clinical and radiographical assessments. Single radiographs focusing on the implant and the impression coping are often used to determine whether the fit between components has been achieved.
In general, however, the current level of ability to detect the presence or absence of a gap at the implant-abutment interface is quite low. Researchers from the University of Bern recently carried out a survey investigating what dentists considered an acceptable gap value versus what they thought would be detectable using radiographical assessments.
The researchers asked thirty prosthodontists from the University of Bern School of Dental Medicine two questions. First, the prosthodontists were asked to estimate the detectable size of the radiographical gap between an implant and the related impression coping. Second, they were asked what the maximum acceptable gap size at this interface would be. The researchers had hypothesised that there would be no difference between these two values.
Contrary to their hypothesis, the researchers found that the detectable gap size at the implant-abutment interface was estimated to be considerably higher than the gap size that would be considered clinically acceptable. The researchers therefore concluded that radiographical assessment cannot be considered precise enough in relation to the estimation in order to make an informed decision about implant impressions. The researchers noted that a practical study is required in order to confirm the results of the survey.