A Revolutionary Impression Tray System By: Trent Smallwood, DDS

Accuracy is everything. How many times have we dentists uttered those words? Within a dental office precision is an essential component to everyday success. Dentistry has been presented with so much technology designed to aid dentists, and their team members in achieving the accuracy we demand and expect. And as impression materials continue to advance, they have far surpassed the stability and performance capabilities of the standard disposable tray.

Among the many facets within modern dentistry, taking an impression is one the most common and unfortunately one of the most compromised. Whether records are needed for crown and bridge fabrication, onlays, quadrant dentistry, veneers, dentures, or diagnostic purposes, the meticulousness of these impressions must be assured to maintain quality and obtain the desired result. As important as the actual impression may be, the carrier, or tray, is equally significant. There are many trays available: triple trays, disposable stock trays, or metal stock trays. To maintain an accurate impression, a rigid, form-fitting tray is needed to ensure that the record accuracy is met. AccuLiner-Products (BORDER-LOCK‚ Tray System, Fig. 1) has helped to develop an impressive semi-custom, single-use tray system that achieves all of these key demands. BORDER-LOCK is the first tray system specifically designed to out perform stock metal trays and achieve results that rival those of custom-made trays. The BORDER-LOCK tray can consistently deliver a predictable, high quality impression.

The BORDER-LOCK single-use system works beautifully in that the optimal tray is not randomly determined by “trying in” various tray sizes; there is a measuring system for selection. The resulting semi-custom fit reduces the impression space, allowing a 30% reduction in impression material and greater dynamic pressure when seating the tray.

Unlike stock disposable trays, the BORDER-LOCK is not made of plastic but of a Plexiglass® material that holds its form masterfully. This tray maintains its rigidity throughout all phases of the impression sequence, eliminating the possibility of distortion caused by flexibility in the tray. This combination of a precise fit and rigidity results in greater impression detail and accuracy.

What makes the BORDER-LOCK system unique is the precision in which the tray is selected before use. Not unlike choosing a shoe that fits the foot, the tray is selected based on the width and form of the arch. The correct tray size is determined by a measuring caliper, which is a compass-like device with two “legs” joined at one end through a hinged connection and small “tabs” on the end of each leg that rotate 360°. The measuring caliper and corresponding selection chart are included with the system.

First, the caliper is used to measure arch width and form (Fig. 2). The measuring caliper has slight tension built into it to maintain the record when removed from the mouth. For maxillary impressions the measurement is taken on the buccal surfaces. Lower measurements are taken on the lingual.

To measure the maxillary arch, open the caliper so that the legs fit bilaterally in the buccal vestibules. With the curvature of the tabs facing in, close the legs so that each tab is brought into contact with the buccal surfaces of the second premolar to second molar. For the mandibular arch, rotate the tabs 180° to face out and place them in contact with the lingual surfaces of the second premolar and second molar (Figs. 3 & 4).

Once the measurement is recorded, the caliper is removed from the mouth without changing the setting (Fig. 5).

The tray size chart included with the system will identify the ideal tray size for the impression (Fig. 6). The size chart is a reusable, laminated placard.

Place the caliper on the size chart in order to align the bilateral tabs with the lines on the chart that corresponds to one of the tray sizes. Once you have a match (the lines on the chart align with the tabs), you should be able to use the selected tray with a high degree of certainty that it will fit the arch with exceptional precision (Fig. 7).

The chart is so easy to use. As the calipers are placed, the correct tray number is determined and the tray is selected. In this case a “45” was selected and removed from the storage kit (Fig. 8). The number selected does not have significance other than identifying the tray.

It is recommended to place the tray into the mouth to confirm that there is no impingement on the soft tissue (Fig. 9).

The BORDER-LOCK trays are made with small horizontal “slits”, or border locks, along the lateral border of the tray (Fig. 10). This locking mechanism aids in the retention of the impression material.

Tray Adhesive is applied (Ivoclar Vivadent) to ensure maximum retention of the impression material (Fig. 11). Other tray adhesives may be used but it is always recommended to follow the manufacturer’s enclosed instructions before placement.

When filling the trays, do not overfill. The tray should be filled with a heavy to medium bodied impression material up to 1mm under the edge of the tray. Preparations should be syringed with a wash material prior to the insertion of the impression tray to eliminate all bubbles (Fig. 12). When seating the tray, concentrate pressure in the posterior area and roll it slowly to the anterior area. Seat the tray until the occlusal surfaces of the teeth are in contact with the inner surface of the tray. Impression material will flow through the border locks into the vestibule. It is essential to apply a light massage to the lip and cheeks to activate the retention mechanism so the tray becomes imbedded in the setting material (Fig. 13).

The impression material should be left to set per the manufacturer’s instructions. Once the impression material has completely set, the trays can be removed. To remove the upper tray, press firmly against the superior palate of the tray. As a result, the tray should be easily loosened and removed from the posterior. For the lower arch, the impression tray is removed by pressing it downwards, against the jaw, while simultaneously supporting the jaw with your free hand. This technique simplifies the removal of the impression tray.

The BORDER-LOCK system will help ensure that an accurate impression is taken and maintained (Fig. 14).

This tray system offers a tremendous alternative for those clinicians that desire the characteristics of a custom tray or are frustrated with standard stock trays and the limitations that they possess. The BORDER-LOCK System is another tool in the contemporary armamentarium available to dentists today. It provides unmatched accuracy with regard to an often overlooked but highly integral procedure in dentistry.

To contact Accu-Liner Products call 1-800-458-6627

In 1997 Dr. Trent W. Smallwood founded the Centre for Contemporary Dental Concepts in Tempe, AZ. Along with consulting and teaching with major dental manufacturers, dental laboratories, and his peers, Dr. Smallwood currently teaches with the Hornbrook Group and in 2003 was named the co-Director of the Advanced Posterior Program. Dr. Smallwood teaches numerous courses at his office for other dentists to learn the most contemporary concepts in today’s dentistry. In 1997 he was honored, and awarded, for excellence in Prosthodontics. Dr. Smallwood lectures nationally, specializing on topics such as Full Mouth Rehabilitation, “10” Minute Multiple Aesthetic Provisionals, and Practice Management. Dr. Smallwood recently authored a publication depicting innovative illustrations of smiles. This publication is designed to aid dentists, patients, and ceramists in providing a platform to expand their aesthetic outcome. He can be contacted at: (480) 894-8101 or via email at tsmallwood@qwest.net.