title: Dental practitioner recruitment for a randomized clinical trial in the field to evaluate the performance of a new glass ionomer restoration material.
abstract: BACKGROUND
  In 2009, we began recruiting dental practitioners across Germany to participate in a clinical trial to evaluate the clinical performance of EQUIA, a new glass ionomer restoration material. The aim of this paper is to discuss the outcomes of the dental practitioner recruitment and outline the process of establishing a practice-based research network.
  
  
  METHODS
  Study proposals were sent to randomly selected dental offices in 29 cities in Germany. The proposals were sent until a minimum of 10 clinics in each city declared participation. Later on, briefing lectures informed the participating practitioners about the design, methods, and material application procedure. Participants were familiarized with the guidelines of Good Manufacturing Practice (GMP) and Good Epidemiological Practice (GEP). A questionnaire describing the characteristics of each dental office was filled out by the participating practitioner. Additionally, participation levels were characterized according to the socioeconomic status and geographic districts of residence in Germany (Regions 0 to 9). The associations between the characteristics were tested by the Kruskal-Wallis Test and Chi-squared test (P < 0.05).
  
  
  RESULTS
  A total of 3194 private dental clinics were invited, 1712 clinics refused to participate, 1195 did not respond to the invitation, and 323 agreed to participate. Only 144 clinics participated in the lectures held in their cities and signed the participation agreement. Based on their geographic location, the highest participation was in Region 2 with a participation rate of 14.3%, and the lowest participation was in Region 6 with a participation rate of 1.7%. Regions with the lowest rate of unemployment and relatively higher rates of income (Regions 7 and 8) had the highest rate of refusals (86%).
  
  
  CONCLUSIONS
  The initial results of the dental practitioner recruitment in this study suggest that the recruitment and pre-randomization design were successful, and by reaching out to a considerable number of private dental clinics to participate, we were able to recruit a smaller number of highly motivated dentists in this clinical study. Regional differences in socioeconomic status, practitioner specialization, and differences in patient health care insurance have to be considered when recruiting dental practitioners for clinical trials.
  
  
  BACKGROUND
  The trial has been registered at Deutsches Register Klinischer Studien (German register of clinical trials) on 6 September 2012 under DRKS-ID: DRKS00004220.
authors: Policlinic of Prosthodontics and Biomaterials, Greifswald University, Greifswald, Germany. klinke@uni-greifswald.de.
authors: Thomas
authors: T
authors: Klinke
authors: Policlinic of Prosthodontics and Biomaterials, Greifswald University, Greifswald, Germany. daboula@uni-greifswald.de.
authors: Amro
authors: A
authors: Daboul
authors: Policlinic of Prosthodontics and Biomaterials, Greifswald University, Greifswald, Germany. schwahn@uni-greifswald.de.
authors: Christian
authors: C
authors: Schwahn
authors: Conservative Dentistry Department, Philipps University of Marburg, Marburg, Germany. rankbg@med.uni-marburg.de.
authors: Roland
authors: R
authors: Frankenberger
authors: Policlinic for Restorative Dentistry and Periodontology, University of Munich, Munich, Germany. hickel@dent.med.uni-muenchen.de.
authors: Reinhard
authors: R
authors: Hickel
authors: Policlinic of Prosthodontics and Biomaterials, Greifswald University, Greifswald, Germany. biffar@uni-greifswald.de.
authors: Reiner
authors: R
authors: Biffar
mesh_terms: D000180:Acrylic Resins; D003764:Dental Materials; D003815:Dentists; D004311:Double-Blind Method; D005069:Evaluation Studies as Topic; D006801:Humans; D018579:Patient Selection; D011446:Prospective Studies; D012822:Silicon Dioxide; D012923:Social Class
chemical_list: D000180:Acrylic Resins; D003764:Dental Materials; C015897:glass ionomer; D012822:Silicon Dioxide