The interocclusal record by various materials and methods will play a positive role in securing the desired occlusion in the fabrication of prostheses. Phillip pfaff in 1756 made the first interocclusal records using natural waxes [1–3]. Since then many materials and techniques have been evolved for recording interocclusal relationship. These materials are basically impression materials that have been modified to give better handling characteristics. These include impression plaster, Dental waxes, ZOE impression paste, acrylic resin, hydrocollides and newer one includes polyether and polyvinylsiloxane bite registration materials [2–9]. Since beginning of era of dentistry, the dental waxes and ZOE impression pastes are used till today as bite registration materials because of ease of manipulation and economically viable, as they are less time consuming and less skill dependent [5–7]. They have been adjudged as base materials for the development of newer materials and methods for recording interocclusal relations of teeth. Hence here it is used as control and comparative material with newly developed bite registration material.
Precise articulation of patient’s diagnostic or working casts is a prerequisite for fabrication of prosthesis . A clinically acceptable prosthesis should be in harmony with the existing stomatognathic system. Recording and transferring of accurate existing occlusal records is of prime importance for a successful restoration. Interocclusal recording of the relationship of the mandible to the maxilla is a simple but complex procedure. The inaccuracies attributed to the interocclusal records can be divided into three categories : 1) The biologic characteristics of stomatognathic system, 2) Manipulation of the material, and 3) The properties of the interocclusal recording materials.
Manipulation of the material such as variations in the manner with which the dentist manages the patient and the material during the clinical phases. Of all the properties of the interocclusal recording materials, most important is the dimensional changes caused due to delay in carrying materials to distant laboratories or delay in articulation or remounting of casts play a key role. To solve all these problems we require an ideal interocclusal recording material which is dimensionally stable with passage of time.
Interocclusal recording materials like wax and zinc oxide eugenol are used since beginning. But introduction of newer elastomeric materials in market has put clinicians in dilemma for the selection and usage. These elastomeric materials are chemically similar to the impression materials that have been used for many years [9–14]. Modifications have been made by adding plasticizers and catalyst to provide different handling characteristics . However, it remains unknown whether these modifications in the parent impression materials have altered their properties like dimensional stability . Delayed articulation of patients casts can occur for various reasons [10–18] therefore, the dimensional stability of interocclusal recording materials is most important in multi setup as all the factors has to be considered and analyzed for the recommendation or conclusion.
The ideal requirements of materials to be used for bite registration are[1–3, 5–7] 1)It should become rigid and exhibit minimal dimensional change after setting 2) It should have limited resistance before setting to avoid displacement of teeth or mandible during closure 3) It should produce accurate record of incisal and occlusal surface of the teeth 4) It should be easy to manipulate 5) It should not produce adverse effects on the tissues involved in procedure 6) It should allow easy verification.
An ideal material for interocclusal record allows the intraoral placement of restorations without extensive adjustments. In order to achieve this goal the use of interocclusal recording materials which are dimensionally stable is of paramount importance. Much work has not been done to judge the dimensional stability; which is needed over a period of time. So multicenter research has been done, to evaluate the time dependent linear dimensional stability of three types of interocclusal recording materials; which gives very clear idea to clinicians with regard to its usage in routine practice and also recommendations for usage of the different materials.