A Randomized Controlled Trial On Testing A New Vertical Dimension Of Occlusion Prior To Restorative Treatment Of Generalized Tooth Wear

This study is a Randomized Controlled Trial (RCT). The aim of the study is to evaluate the necessity to test the increased Vertical Dimension of Occlusion (VDO) prior to restorative treatment of generalized tooth wear.

Tooth wear is a physiological phenomenon, that when becoming pathological, can result in functional problems such as pain, reduced quality of life and esthetic impairment. Restorative treatment should be discussed in with patients with severe or pathological tooth wear.

The restorative treatment includes restoration of all teeth, separately, in increased VDO. The increment of VDO is based upon clinical parameters as the amount of loss of natural tooth tissue, the possibility to lengthen the maxillary anterior teeth in regard to an acceptable esthetic outcome, and the Free Way Space (FWS). The FWS is the intermaxillary space when the masticatory-muscles-complex is relaxed.

Traditionally, it is believed that adapting to a new VDO results in clinical difficulties such as different speech, pain of the Temporo Mandibular Joint (TMJ), masticatory muscle pain, and increased masticatory muscles activity. The latter could result in an increased bite force and an increased failure rate of restorations. Some operators, then, prefer to test the increment of VDO prior to restorative treatment to check if patients can adjust to the new VDO. This raises the question if the needed increment of VDO to restore worn dentitions should be checked prior to restorative treatment. The hypothesis in this study is that testing the needed increment of VDO prior to restorative treatment does not improve the adaptation to the restorative treatment.

The research was registered in the ClinicalTrial.gov register after the study had been completed. This RCT is part of RCT with a 2x2 design. The first branch was used to randomize patients to certain restorative protocol, which was enlisted in ClinicalTrials.gov (NCT04326816). The second branch was designed to test the VDO prior to restorative treatment of generalized severe tooth wear. Approval of the local Medical-Ethics-committee (METC) for the 2x2 RCT was sought and granted in 2010. Approval was granted to a protocol in which no Data Safety Monitoring Board was appointed as research standards were different in 2010. The study was conducted according to the principles of the Declaration of Helsinki and in accordance with the Medical Research Involving Human Subjects Act (WMO).