Trends in Selection, Usage, and Techniques of Interocclusal Record Materials among Private Dental Practitioners: A Survey.

BACKGROUND: Majority of general dental practitioners provide fixed dental prosthesis in India. The aim of this study was to gather information on selection, usage, and materials and methods employed in interocclusal records and their communication with the dental laboratory for restorative procedures practised by dentists in Indore district to evaluate and to improve the quality of current practice. AIM AND
OBJECTIVES: The purpose of this cross-sectional study was to understand and to evaluate dental practitioner's knowledge on interocclusal recording materials, its usage, their clinical implications, and their correlation with the laboratory in restorative procedures practiced by the dental practitioners in Indore district.
MATERIALS AND METHODS: A questionnaire comprising 11 questions were framed and circulated among general dental practitioners except prosthodontists, and the results were statistically analyzed.
RESULTS: Most of the practitioner's preferred wax (54.6%) as an interocclusal recording material over polyvinylsiloxane and polyether. Most of the dentists preferred full arch interocclusal record (27.8%). About 51.5% clinicians trimmed the interocclusal record before sending to the laboratory.
CONCLUSION: From this survey, it has been concluded that the practitioner's attitude toward the use of interocclusal record materials is found to be deviated from well-acknowledged prosthodontic quality guidelines.

Introduction

Prosthodontics is an authority which requires synergy between dentist and dental technician to fabricate intraoral prosthesis with acceptable fit, function, comfort, and esthetics.[123] The fabrication of indirect restorations should be precise so that its insertion in the mouth will be in harmony with the existing stomatognathic system.

An accurate and usable occlusal record is very important, and any inaccuracy may lead to extensive intraoral adjustments which may compromise esthetics and/or mechanical strength of restorations. The results of a survey published in 2000 highlighted the problems which technicians face with fixed prosthodontics.[4] One of the most commonly encountered problem was poor interocclusal records; which almost inevitably got translated into some form of occlusal discrepancies in the final restorations.[56] Such errors are magnified when several teeth are prepared or missing and whenever the terminal tooth is prepared in a unilateral fixed partial denture.

It is not uncommon to see that textbook of crown and bridgework and dental materials go around the subject of occlusal recording materials, often with no mention regarding technique of recording and troubleshooting being made at all.[6]

According to GPT 8: “The interocclusal record is a registration of the positional relationship of the opposing teeth or arches.”[7] It should be an accurate and dimensionally stable representation of an interocclusal space that is subsequently transferred to an articulator. Plaster, wax, zinc oxide–eugenol paste, autopolymerizing acrylic resin, polyether, and polyvinyl siloxane are materials clinically in use for this purpose.[89]

Once the record is made and removed from the mouth, only minor changes, such as trimming, are permitted, and its final accuracy is many times assumed without verification. Too often this assumption is incorrect and the need to make it represents a serious deficiency in making the record. There are difficulties with the manipulation of the materials such as nonuniform heating of wax, improper recording of the record, transfer of the record to the laboratory is not in a proper way which may involve discrepancy in the record, and finally in the prosthesis.[810]

A previous survey on communication methods and production techniques used by dentists and dental technicians for the fabrication of fixed prosthesis in the UK from the dental technician's perspective reported that only 11% of occlusal records received by dental laboratories were accurate and usable, and the rest were either not usable or not accurate and discarded. This cross-sectional study was carried out among private dental practitioners to understand their knowledge and skill on handling interocclusal records.[111]

Materials and Methods

The present cross-sectional study was conducted to assess the materials and techniques used for interocclusal records in fixed prosthodontic cases.

A total of 500 dentists participated in the study and out of which 490 answered the questionnaires. The questionnaire was provided to the general dental practitioners only. Prosthodontists were excluded from the study.

A pilot study was carried out with a group of 10 dentists. Based on the results of pilot study, certain improvements were made in the questionnaire, and survey was conducted in various parts of Indore district in central India.

Questions were framed aiming to collect general information, about the qualification, specialty of the dentist, knowledge and materials choice for interocclusal records, cases selected, techniques followed for manipulation of particular interocclusal material, checking, handling, and storage of records and mode of transfer of records to the laboratory technicians.

The returned questionnaire was reviewed for completeness and analyzed statistically. The answers were represented in the form of percentage.

Results

A total of 490 out of 500 practitioners answered the questions, and 10 respondents answered only some of the questions which were found to be incomplete so they were excluded at the time of analysis of data. The results presented in this study pertain to the subcategories of general information, materials usage, finishing of a record, storage of a record, and consistent recordings. The subcategories and questions along with the results in parentheses are depicted in the following Tables 1–5.

Table 1

Questionnaire of selection, usage, and techniques of interocclusal record materials

Table 5

Storage of a record

Discussion

In clinical practice, almost every clinician performs crown and bridge work. It should be borne in mind that, in addition to exacting the technical requirements involved in the use of interocclusal recording materials, the methods and techniques of registration, storage, and transport of record to the laboratory should be taken into account.[358] These, to a greater extent, depend on the individual approach and skill of each dentist.

This cross-sectional survey was undertaken to identify the attitude about selection, usage, and techniques used for different interocclusal recording materials by the general dental practitioners for the fabrication of fixed prostheses within Indore district in central India.

The questionnaire results were assessed, in general, and it was found that the vast majority of the respondents did not use recommended interocclusal recording materials and techniques and it seems that recent materials and techniques did not gained popularity and credibility in the preclinical prosthodontic teaching in various fixed prosthodontic cases. Recently, polyether and polyvinylsiloxane have been developed as impression materials and are now being marketed as interocclusal registration materials. Although wax is probably the most maligned, it is yet the most versatile and widely accepted material.[9] This is due to its cost and ease of manipulation.[12] Records of impression plaster are accurate, rigid after setting and do not distort with extended storage; however, it is difficult to handle because the material is fluid and unmanageable before setting. Zinc oxide eugenol paste is simple to use, sufficiently rigid, and easy to store,[9] but it is extremely variable and consistently resulted in an open cast relationship.[13] Acrylic resins showed dimensional instability due to continued polymerization resulting in shrinkage.[9]

The different interocclusal record material affects the accuracy of the mounting casts on the articulator; however, the vinyl polysiloxane seemed to improve both horizontal and vertical stability due to its inherent rigidity and dimensional stability.[1013]

The results of this study showed that a significant number of dental practitioners (79%) use interocclusal recording materials for the fabrication of crowns and bridgeworks. The most commonly use interocclusal recording material was wax (54.6%), and polyvinylsiloxane (3.1%) and zinc oxide eugenol and acrylic resin (1%) were the least used material, and 40.2% practitioners use all types of record materials. Although wax is probably the most maligned, it is yet the most versatile and widely accepted material.[9] It was found that pink baseplate wax was the most frequently used material rather than recommended aluminum impregnated wax. This is due to its cost and ease of manipulation.[12] On the other hand, most of the general dental practitioners are not sufficiently aware about elastomeric interocclusal recording materials and their knowledge and inclination to use these materials is seemed to be less as compared to the prosthodontists.

For manipulation procedure, most of the practitioners manipulate wax by direct heating over flame (50.5%). Ideally, wax should be manipulated using water bath at a temperature of 54°C–60°C (130–140° Fahrenheit)[14] before record making. Very few dental practitioners prefer polyvinylsiloxane and polyether, and out of them i.e. 2.1% preferred a method of direct syringing on occlusal surfaces using a mixing dispenser.

During recording procedure, the majority of the dental practitioners (27.8%) prefer to place an interocclusal recording material over the full arch, 27.8% took records by placing the material over the quadrant which is involving prepared teeth, and 25.8% place the material over the prepared teeth only. 58.8% did not use the tray for manipulation procedure and 15.5% used tray for manipulation. When one or two teeth are missing, segmental records should be made and in distal extension cases, and where multiple teeth are lost, records should be made over the full arch.[1516] In previous studies, it has been suggested that interocclusal recording materials can be manipulated without using a tray.[17]

Furthermore, >50% do trimming and finishing of record after it has set and before sending to laboratory. This step is basically very crucial for mounting procedure and to check reproducibility of the record, so the record should be accurate without any flush.[18] If finishing of record is not done, it may cause open cast relationship and which may cause changes in the final prosthesis.[1719] Majority of them transfer the record to laboratory in 1–24 h (62.9%) and 37.1% transfer within 1 h. The ideal time required for the record to be articulated is polyether interocclusal records must be articulated within 48 h, Polyvinylsiloxane interocclusal records must be articulated within 24 h and wax, and zinc-oxide eugenol should be articulated within 1 h to get accurate registration.[20] If the wax is not articulated within 1 h, distortion may occur in it because of volatiles loss and stress release property.[212223]

A concerning finding of this survey was that practitioners send separate casts and interocclusal record (38.1%), 28.9% send impression and record, and 27.8% send hand articulated casts with interocclusal record between the casts. It has been seen that hand articulation is the procedure that can be accepted for transfer of record. Hand articulation of casts is a more reliable and accurate method of relating the casts at maximum intercuspation rather than sending an impression and record separately to the laboratory.[2425]

Around 44.3% use cold water for the storage of record if the wax record is not sent to the laboratory for a particular time and 24.7% store it at room temperature. If the wax is used, it should be stored in chilled water, and other records should be kept in open air.[26] About 74.2% said that laboratory technician insists for the usage of interocclusal record; however, dental practitioners should know the conditions where interocclusal record[2728] should be used rather than after being insisted by laboratory technicians.

Due to the evolution of newer materials and techniques, interocclusal registration procedure is becoming more precise and better thus reducing the problems in rehabilitating procedure of function and esthetics. There are various techniques as bite registrations for computer-aided design, computer-aided manufacturing procedures, photoocclusion, T-scan, occlusion sonography, etc.[29303132]

Clinical implication of the study

Most dentists often have to deal with crowns or simple fixed prosthesis that requires occlusal adjustment. Proper impressions and mounting of casts can reduce or eliminate the problem. It is important that dental students, and subsequently dentists, are competent in fixed prosthodontics. These topics need immediate and in-depth attention from instructors in dental schools and dental continuing education programs.

Limitation

The limitation of this study includes the fact that sample belongs to a local area and so result cannot be equally extrapolated to all the general practitioners.

Conclusion

This study investigated the use of interocclusal recording materials among general dental practitioners working in private offices in Indore district. It demonstrated that dentists performed crown and bridge work on the large amount but which is often deviated from well-acknowledged prosthodontic quality guidelines. Dentists do not use polyvinylsiloxane/polyether interocclusal record materials and frequently use wax for prosthodontic rehabilitation procedures. General practitioners did not seem to keep up with recently introduced materials and techniques but use more conventional methods. This necessitates the need for training the undergraduates in interocclusal record making and communicating the same to the laboratory.

From this survey, it has been concluded that the practitioner's attitude toward the use of interocclusal record materials is found to be deviated from well-acknowledged prosthodontic quality guidelines.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Table 2

Subcategories of the questionnaire with answers in percentage- General information

Table 3

Manipulation technique applied by the dental practitioners

Table 4

Finishing and handling of a record