Convergence angles of tooth preparations assessed on dies for full crowns and bridge retainers

  • A.K. Ombuna
  • S.W. Maina
  • K.B. Alasow
  • B.K. Kisumbi
  • L Gathece


Objective: The aim of the study was to assess the convergence angles of tooth preparations on dies for full crowns and bridge retainers done by oral health providers in Nairobi, Kenya. Study design: This was a descriptive cross sectional study.

Setting: Selected dental laboratories in Nairobi, Kenya.

Subject: Dies of full crown and bridge retainers.

Results: A majority (59%) of the tooth preparations were for single crowns and 41% were for bridge retainers. The mean convergence angle for all the dies was 24.0○ with a mean buccal-lingual convergence angle of 26.7 ○ +11.93SD and a mean mesio-distal convergence angle of 22.1 ○ +10.89SD. Ideal tooth preparations were found in 18.1% of the dies. Majority of which were for single crowns (58.9%) followed by the abutment preparations for three unit bridges at 23.2%.

Conclusion: Most of the tooth preparations did not have both ideal mesio-distal and buccal-lingual convergence angle measurements. There is therefore a need to provide Continuing Professional Education courses for dentists on tooth preparation for crown and bridge to enhance clinical application of tooth preparation guidelines.


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eISSN: 0012-835X