M Oliver Ahlers1,2, Daniel Edelhoff3, Holger A Jakstat4. 1. Department of Prosthetic Dentistry, School of Dental and Oral Medicine, University Hospital Hamburg-Eppendorf, University of Hamburg, Hamburg, Germany. Ahlers@UKE.de. 2. CMD-Centre Hamburg-Eppendorf, Falkenried 88 (CiM, Haus C), 20251, Hamburg, Germany. Ahlers@UKE.de. 3. Department of Prosthetic Dentistry, University Hospital, LMU Ludwig-Maximilians-University, Munich, Germany. 4. Preclinical Education and Dental Materials, Department of Prosthetic Dentistry, School of Dental and Oral Medicine, Medical Faculty, University of Leipzig, Leipzig, Germany.
Abstract
OBJECTIVES: The benefit from positioning the maxillary casts with the aid of face-bows has been questioned in the past. Therefore, the aim of this study was to investigate the reliability and validity of arbitrary face-bow transfers compared to a process solely based on the orientation by means of average values. For optimized validity, the study was conducted using a controlled, randomized, anonymized, and blinded patient simulator study design. MATERIAL AND METHODS:Thirty-eight undergraduate dental students were randomly divided into two groups; both groups were applied to both methods, in opposite sequences. Investigated methods were the transfer of casts using an arbitrary face-bow in comparison to the transfer using average values based on Bonwill's triangle and the Balkwill angle. The "patient" used in this study was a patient simulator. All casts were transferred to the same individual articulator, and all the transferred casts were made using type IV special hard stone plaster; for the attachment into the articulator, type II plaster was used. A blinded evaluation was performed based on three-dimensional measurements of three reference points. RESULTS: The results are presented three-dimensionally in scatterplots. Statistical analysis indicated a significantly smaller variance (Student's t test, p < 0.05) for the transfer using a face-bow, applicable for all three reference points. CONCLUSIONS: The use of an arbitrary face-bow significantly improves the transfer reliability and hence the validity. CLINICAL RELEVANCE: To simulate the patient situation in an individual articulator correctly, casts should be transferred at least by means of an arbitrary face-bow.
RCT Entities:
OBJECTIVES: The benefit from positioning the maxillary casts with the aid of face-bows has been questioned in the past. Therefore, the aim of this study was to investigate the reliability and validity of arbitrary face-bow transfers compared to a process solely based on the orientation by means of average values. For optimized validity, the study was conducted using a controlled, randomized, anonymized, and blinded patient simulator study design. MATERIAL AND METHODS: Thirty-eight undergraduate dental students were randomly divided into two groups; both groups were applied to both methods, in opposite sequences. Investigated methods were the transfer of casts using an arbitrary face-bow in comparison to the transfer using average values based on Bonwill's triangle and the Balkwill angle. The "patient" used in this study was a patient simulator. All casts were transferred to the same individual articulator, and all the transferred casts were made using type IV special hard stone plaster; for the attachment into the articulator, type II plaster was used. A blinded evaluation was performed based on three-dimensional measurements of three reference points. RESULTS: The results are presented three-dimensionally in scatterplots. Statistical analysis indicated a significantly smaller variance (Student's t test, p < 0.05) for the transfer using a face-bow, applicable for all three reference points. CONCLUSIONS: The use of an arbitrary face-bow significantly improves the transfer reliability and hence the validity. CLINICAL RELEVANCE: To simulate the patient situation in an individual articulator correctly, casts should be transferred at least by means of an arbitrary face-bow.