Christo Metschkaroff May 1, 2011:

Undercut <--> Retention Моля сравнете в: http://books.google.com/books?id=oIcsi7ojCs4C&pg=PA125&dq="u... стр. 125. Вж. също за Retention в: http://www.answers.com/topic/retention, част: Mosby's Dental Dictionary: retention

Petar Tsanev (asker) Apr 27, 2011:

More context Polysiloxanes have very good biological compatibility and up to now no harmful reactions or secondary effects on patients and/or dental personnel are known. Impression materials are intended to set in the mouth of the patient, however, they should remain in the mouth not more than twice the setting
time. Although they have reasonably high tear strength, care should be taken that no portion of the impression material remains in the interdental spaces or in the sulcus. Undercuts should, in certain instances, be blocked out before taking the impression.