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What made this keyway partial fit

14 October 2026 restorativeprosthodonticscase

This is the case from my keyway reel. Avant Dental wrote it up in full, visit by visit, and the link is at the bottom. Here’s the short version and the three things I’d tell another dentist before they try one.

The case

A 62 y/o male was about to start bisphosphonates for severe osteoporosis. He had one upper tooth left, the 25. In the lower, 32 to 42 had little bone support and decay. 33, 34 and 43 were sound but didn’t offer much retention, and there wasn’t much bone at the back to support a denture. He didn’t want clasps showing.

The extractions went first, with healing time before the bisphosphonates started, to lower the risk of medication-related osteonecrosis of the jaw (MRONJ).

The plan was a full upper denture and a lower cobalt chrome partial. PFM crowns on 34 and 43 carry key and keyway precision attachments with milled reciprocal arms, and 33 has a PFM crown too. The attachments do the retaining, so nothing shows.

Fitting surface of the lower chrome partial, with the crowns seated in their keyways

What made it fit

  1. A pick-up impression with the crowns seated. Once the crowns fit at try-in, I took a PVS pick-up impression with them in place. The framework was built to where the crowns actually sit in the mouth.
  2. Crowns cemented last, with the denture in. The three crowns went in at the final visit with the finished lower denture seated, using RelyX Universal, and glycerine on the chrome to keep excess cement off the framework.
  3. My mistake: the temporaries. I made new Luxatemp temps at every visit until Avant made PMMA ones at visit 5. With this many visits, I’d have the lab make PMMA temps from the prep appointment.

The seven visits

  1. Extract 25 and 32 to 42, then let it heal before the bisphosphonates start.
  2. Intraoral scan, and plan it with the lab.
  3. Prep 33, 34 and 43, scan, and Luxatemp temps.
  4. Crown try-in, and the PVS pick-up impression with the crowns seated.
  5. Bite registration and framework check. Lab PMMA temps replace the Luxatemp.
  6. Try-in of the full upper and the lower chrome partial.
  7. Cement the three crowns with the lower denture seated, then insert and check the fit.

He felt some pressure at first, which settled, and both dentures were firm and stable.

The lab work was by Ian Feigen and the team at Avant Dental.

Read the full case on Avant Dental’s site

Regulatory Information: Images/videos posted with patient consent. No filters, AI enhancements, or unrealistic lighting used. For educational purposes only, not medical advice. Surgical/invasive procedures carry risks; individual results vary. Seek a second opinion from a qualified practitioner before treatment. Dr William Shield - Registered General Dentist DEN0002139093