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

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.