Many publications report about positive clinical experiences with different types of double crowns as attachment for all kinds of RPD's. However precise values about abutment tooth mobility are rare. There are concerns of uncontrolled abutment tooth overloading caused by frictional telescopic retention in severely compromised dentitions with 1 to 3 remaining teeth. Aim of this prospective follow up - pilot study was to determine, whether friction fitting telescopic crowns increase tooth mobility and increase the risk of tooth loss under subtotal dentures. A convenience sample of 12 patients with 1 to 3 remaining teeth in one jaw receiving 13 prostheses with 26 frictional fitting telescopic crowns was reexamined eighth times in 36 months. Abutment tooth mobility was monitored with the help of the Periotest instrument (PTV). The survival rate was 100% (dentures and supporting telescopic abutment teeth). The initial strengthening of the abutment teeth, as reported in previous studies, could be confirmed. Mean PTVs decreased over a period of 36 months significantly (p=0,010). PTV - courses in both sexes (p=0,015), in both jaws (p=0,019) and for abutment number /1-3/ (p=0,034) were influenced significantly by the factor time, whereas wearing habits were not (p=0,988). The factors sex (p=0,047) and jaw (p0,001) influenced PTVs significantly. The factors abutment number (p=0,363) and wearing habit (p=0,330) influenced the PTVs not significantly. The significant interaction between wearing habit and PTV-change in the course of time seems to be important. In 84,5% of the dentures relining was required. Denture repairs were necessary in 15,4%. Conservative and endodontic treatment was made in 14,3%. In 14,2% (tooth/examination) periodontal treatment (including 58,3% remotivation) was carried out. The recementation rate was 7,7%. All patients were satisfied with their prostheses.