Impression evaluation and laboratory use for single-unit crowns: Findings from The National Dental Practice-Based Research Network

J Am Dent Assoc. 2017 Nov;148(11):788-796.e4. doi: 10.1016/j.adaj.2017.06.015. Epub 2017 Aug 16.


Background: Objectives were to determine the likelihood that a clinician accepts an impression for a single-unit crown and document crown remake rates.

Methods: The authors developed a questionnaire that asked dentists about techniques used to fabricate single-unit crowns. The authors showed dentists photographs of 4 impressions and asked them to accept or reject each impression. The authors correlated answers with dentist and practice characteristics. Other questions pertained to laboratory use and crown remake rates.

Results: The response rate was 83% (1,777 of 2,132 eligible dentists). Of the 4 impressions evaluated, 3 received consistent responses, with 85% agreement. One impression was more equivocal; 52% accepted the impression. The likelihood of accepting an impression was associated significantly with the clinician's sex, race, ethnicity, and practice busyness. Clinicians produced 18 crowns per month on average, and 9% used in-office milling. Most dentists (59%) reported a remake rate of less than 2%, whereas 17% reported a remake rate greater than 4%. Lower remake rates were associated significantly with more experienced clinicians, optical impressions, and not using dual-arch trays.

Conclusions: Although dentists were largely consistent in their evaluation of impressions (> 85%), nonclinical factors were associated with whether an impression was accepted or rejected. Lower crown remake rates were associated with more experienced clinicians, optical impressions, and not using dual-arch trays.

Practical implications: These results provide a snapshot of clinical care considerations among a diverse group of dentists. Clinicians can compare their own remake rates and impression evaluation techniques with those in this sample when developing best practice protocols.

Keywords: Crowns; dental laboratory; impressions; practice network; remake rates.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Crowns*
  • Decision Making
  • Dental Impression Materials
  • Dental Impression Technique / statistics & numerical data*
  • Dental Prosthesis Design / statistics & numerical data*
  • Esthetics, Dental
  • Humans
  • Practice Patterns, Dentists' / statistics & numerical data*
  • Surveys and Questionnaires
  • United States


  • Dental Impression Materials