CLINICAL PRACTICE
" DOUBLE STEP REVERSE”( DSR): A NEW PROTOCOL IN POLYVINYLSILOXANES( PVS) IMPRESSION-TAKING PROCESS- TWO CASE REPORTS
Enrico Manca 1a *, Marco Fazio 2b, Riccardo Aiuto 2c, Giacomo Derchi 1, 3d
1
Department of Surgical Pathology, Medicine, Molecular and Critical Area, University of Pisa, Pisa, Italy
2
Private Dental Practice
3
Tuscan Stomatologic Institute, Lido di Camaiore, Italy a
DDS, Professor in University Master Degree in Oral Implantology, Clinical Dentist in Cagliari( Italy) b
DDS, Clinical Dentist in Palermo( Italy) c
DDS, Clinical Dentist in Milano( Italy) d
DDS, MSc, PhD, Assistant Professor, Clinical and Research Fellow
Received: July 09, 2016 Accepted: July 11, 2016
Available online: September 12, 2016
Cite this article: Manca E, Fazio M, Aiuto R, Derchi G.“ Double Step Reverse”( DSR): a new protocol in polyvinylsiloxanes( PVS) impression-taking process- two case reports. Stoma Edu J. 2016; 3( 2): 184-192.
ABSTRACT
Aim The aim of this case report is to describe a new protocol which can be useful to the clinician and can lead to a less frustrating process while taking dental impressions for fixed prosthodontics. Summary With the“ Double-Step Reverse” technique it is shown that it is easier to take excellent impressions, especially in the post-space and in the multiple preparation impressions, without worrying about V-shaped voids and bubbles on the finishing line. Key learning points The DSR protocol requires that the wash material( Aquasil Ultimate) is first delivered on preparations, then we wait for its complete setting and later we deliver the tray material, with an impression tray. The DSR technique allows greater patient cooperation and greater serenity during the 3 minutes of the setting time. It is time-saving and reduces the waste of polyvinylsiloxanes( PVS) materials. Keywords: prosthetic dentistry, PVS impressions, accuracy, dental materials, double-step impressions.
1. Introductions The impression-taking process has always been a delicate step in fixed and removable prosthodontics; several techniques and materials have been evaluated with varying degrees of success. The scientific papers provide us with comparisons between different impression techniques and different materials, so it is hard to find a unique agreement. On the other hand, the dental supplies offer many types of hydrocolloid materials, polyether, polysulfide and polyvinylsiloxanes( PVS). The importance of the quality of a dental impression is well known and it is shown by many articles that compare not only the available materials 1-2-3, but also the impression techniques 4-5. Material and technique are not the only factors that affect the accuracy of impression. In 2004 Perakis, Belser, Magne 6-7, in a review, considered, among other things, the rheology of materials, remembering the three phases of process: 1) Viscous phase which allows mixing and handling; 2) Plastic phase for the adaptation to the anatomy of the mouth; 3) Elastic phase that allows the removal of the material overcoming any undercuts. The authors pointed out that polyvinylsiloxanes( PVS) move rapidly from a viscous to an elastic phase, then requiring a short working time after mixing. Thus, compared to polyether( PE), PVS have a shorter plastic phase. On the other hand, the rigidity of the PE, twice as double the PVS, often makes the disconnection difficult. These data are confirmed by the work of McCabe in 1998 8. A brand new PVS, coupled with a handpiece that is attached to the turbine hose, mixes and dispenses the wash material under pressure. Thanks to the characteristics of this new PVS and method of application it is possible to apply the wash material on preparations, then wait for its complete polymerization and later on the tray material is applied. This is called the new Double Step Reverse technique( DSR). The purpose of this paper is to show a new protocol to take impressions in polyvinylsiloxanes( PVS)
* Corresponding author:
Dr. Enrico Manca, DDS, Studio Enrico Manca, Via Giovanni Battista Tuveri, 108, I-09129 Cagliari, Italy Tel / Fax: 070-485-337; e-mail: infostudiomanca70 @ gmail. com
184 STOMA. EDUJ( 2016) 3( 2)