Clinical Oral Investigations

, Volume 14, Issue 5, pp 607–611 | Cite as

Retention force measurement of telescopic crowns

  • Stefan BayerEmail author
  • Helmut Stark
  • Sebastian Mues
  • Ludger Keilig
  • Anja Schrader
  • Norbert Enkling
Original Article


This study deals with the determination of the retentive force between primary and secondary telescopic crowns under clinical conditions. Forty-three combined fixed–removable prostheses with a total of 140 double crowns were used for retention force measurement of the telescopic crowns prior to cementation. The crowns had a preparation of 1–2°. A specifically designed measuring device was used. The retentive forces were measured with and without lubrication by a saliva substitute. The measured values were analyzed according to the type of tooth (incisors, canines, premolars, and molars). Additionally, a comparison between lubricated and unlubricated telescopic crowns was done. As maximum retention force value 29.98 N was recorded with a telescopic crown on a molar, while the minimum of 0.08 N was found with a specimen on a canine. The median value of retention force of all telescopic crowns reached 1.93 N with an interquartile distance of 4.35 N. No statistically significant difference between lubricated and unlubricated specimens was found. The results indicate that retention force values of telescopic crowns, measured in clinical practice, are often much lower than those cited in the literature. The measurements also show a wide range. Whether this proves to be a problem for the patient’s quality of life or not can however only be established by a comparison of the presented results with a follow-up study involving measurement of intraoral retention and determination by e.g. oral health impact profile.


Retention force Withdrawal force Telescopic crown Double crown Denture Friction 


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Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Stefan Bayer
    • 1
    • 3
    Email author
  • Helmut Stark
    • 1
  • Sebastian Mues
    • 1
  • Ludger Keilig
    • 2
  • Anja Schrader
    • 1
  • Norbert Enkling
    • 1
    • 3
  1. 1.Department of Prosthodontics, Preclinical Education and Dental Materials ScienceUniversity of BonnBonnGermany
  2. 2.Oral TechnologyUniversity of BonnBonnGermany
  3. 3.Clinic for Prosthetic DentistryUniversity of BernBernSwitzerland

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