Accurately Seating Inclusive® Custom Abutments Using an Acrylic Jig
In processing restorations for more than 100,000
implant cases, the Implant department at Glidewell Laboratories has accumulated a unique understanding of the industry as a whole, observing everything from shifting trends, to emerging techniques, to common difficulties experienced by practicing clinicians. In this column, we endeavor to share some of the insights we have obtained, in hopes of improving the quality and efficiency of cases everywhere.
Among the most popular products in implant dentistry today are CAD/CAM custom abutments. An investment in cutting-edge digital technology and state-of-the-art milling equipment here at Glidewell Laboratories enables us to efficiently and precisely design and mill our own Inclusive® Custom Implant Abutments. In our experience, custom abutments are superior in almost every way to stock, off-the-shelf abutments. After all, a restoration is only as good as the foundation on which it is placed. And if that foundation is less than ideal in terms of size, shape, angulation or tissue contour, the success of that restoration could be compromised.
Inclusive Custom Implant Abutments are available in three varieties: Titanium, All-Zirconia or Zirconia with Titanium Base. Titanium is most often the choice for posterior restorations because the popular perception among dentists is that this metal alloy must be stronger than zirconia. Our testing data suggests that this may not necessarily be true, in that a properly designed zirconia connection has been shown to tolerate greater loads than a titanium connection. The traditional opinion persists, it seems, due to the fundamental nature of a metal, which deforms under stress, versus a ceramic, which fractures. Regardless, the most widely accepted advantage of a zirconia abutment is its improved esthetics. Having a tooth-colored foundation, rather than a metal one, allows the lab technician to increase the translucency of the crown or bridge. It also eliminates the risk of the gray color of the metal shining through thin soft tissue. For this reason, zirconia abutments are more often used in the esthetic region (Fig. 1).
This brings us to the question of which type of zirconia abutment – All-Zirconia or Zirconia with Titanium Base – should be used. Considerations here are two-fold. One is the length of the abutment connection (the post-like section of the abutment that engages into the implant). Zirconia connections are designed to be short for improved strength – superior even to the strength of a titanium connection – but this shortened length can sometimes present a challenge in terms of verifying complete seating of the abutment onto the implant. Titanium connections are longer (Fig. 2), making them easier to seat, assuming adequate vertical clearance. The second consideration, however, goes back to the difference in esthetics. With a titanium base, there remains the small risk of the appearance of metal showing through around the base of the abutment. With an all-zirconia abutment, this potential drawback is eliminated.
In terms of practical use, how does the clinician who desires an all-zirconia custom abutment ensure proper seating? For the lab technician, seating the abutment on a model is easy. The model can be turned or twisted as needed to achieve optimal orientation, and there are no other anatomical structures or tissues to get in the way. A patient in the chair, however, is another matter. There's only so much freedom the clinician has in terms of orientation to gain access to the implant site. And there are cheeks, teeth, the tongue and soft tissue to contend with. In addition, the lab technician is frequently more familiar with the line of draw as a result of the intimacy gained during the design process. Without spending the same amount of time relating the abutment to the patient's mouth, the doctor cannot be expected to have this level of familiarity. To help solve this clinical challenge and ensure proper seating of the abutment, an acrylic jig can be made, which serves as a positioning index and placement aid. From Glidewell, this jig is shipped in the case box in a plastic baggie separate from the abutment (which is seated on the model). Upon close examination, you will see that both the jig and the abutment are marked with the appropriate tooth number along the facial wall (i.e., labial or buccal). Thus, if your case includes multiple abutments, each abutment can easily be matched to the correct jig.
Laboratory Example
Figure 3, Figure 4 and Figure 5 illustrate an Inclusive All-Zirconia Abutment with jig, as prepared on a laboratory model.
Clinical Delivery
The following procedure outlines the specific steps for placing an Inclusive All-Zirconia Abutment with its matching jig. As noted, the same steps may be applied when placing other Inclusive Custom Abutments or screw-retained restorations.
To properly seat a custom abutment with its custom-matched jig:
- Match the selected abutment to the jig with corresponding tooth number on the model (Fig. 6).
- Place the abutment in the jig. For proper orientation, vertically align the number marked on the abutment to the number marked on the jig. The two should slide together easily.
- Using the jig as a carrier, deliver the abutment to the patient's mouth.
- Align the numbers marked on the jig and carrier with the facial wall of the patient's arch (i.e., labial or buccal). When properly aligned, apply pressure to seat the jig and abutment. Proper seating of the jig will help ensure full seating of the abutment (Fig. 7).
- Using your driver, insert the abutment screw and tighten. Note that the jig will also maintain the position of the abutment while the screw is tightened to the recommended torque (Fig 8).
- Remove the jig, leaving the tightened, fully seated abutment in place (Fig. 9). A periapical film should be taken to ensure complete seating.
Alternate Uses of the Laboratory Jig
Screw-Retained BruxZir® Solid Zirconia Crown
The use of a jig is not limited solely to custom implant abutments. It may also be used to seat single-unit, screw-retained restorations. Figure 10 and Figure 11 illustrate a screw-retained BruxZir® Solid Zirconia crown with jig, as prepared on a laboratory model.
Multiple-Unit Bridge
A jig may also be used for multi-unit applications. Figure 12, Figure 13 and Figure 14 illustrate a pair of Inclusive Titanium Abutments with accompanying jig, as prepared on a laboratory model. In this case, the abutments will be used to support a multi-unit bridge.
Delivery of a Screw-Retained BruxZir Solid Zirconia Crown
The same procedure used to seat an Inclusive Custom Abutment can be used to ensure proper seating of a screw-retained BruxZir Solid Zirconia crown, as demonstrated by Figure 15, Figure 16, Figure 17a and Figure 17b.
Summary
All-zirconia custom implant abutments offer a natural esthetic and significant abutment connection strength, but the short length of the abutment connection can pose a clinical challenge when it comes to proper seating. Using the jig-assisted delivery technique outlined above makes the process of seating any Inclusive Custom Implant Abutment quick and convenient, no matter the length of the implant-abutment connection. It works well for single-unit restorations, and even better for bridges, where a single jig is used to seat multiple units. (This is typically limited to three units per jig, as larger spans can become cumbersome to handle in the mouth.) With this method, doctors have seated a full-arch roundhouse in a matter of minutes. All the clinician has to do is ensure proper alignment between abutment and jig, and then again between jig and implant site. If the lab has done its job correctly, the precise nature of digital CAD/CAM processing will ensure a successful outcome every time.
Dzevad Ceranic began his career at Glidewell Laboratories while attending Pasadena City College's dental laboratory technology program. In 1999, Dzevad began working at Glidewell as a waxer and metal finisher, then as a ceramist. After being promoted to general manager of the Full-Cast department, he
assisted in facilitating the lab's transition to CAD/CAM. In June 2008, Dzevad took on the company's rapidly growing Implant department, and in 2009 completed an eight-month implants course at the UCLA School of Dentistry. Today, Dzevad leads a team of 170 people at the lab and continues to implement cutting-edge technology throughout his department. Contact him at 
