Practical Implant Techniques That Will Impress Your Dentists

Any debris retained also has the potential to significantly affect the fit of the abutment and the restoration. Poorly fitting abutments will increase occlusal adjustments, produce more leakage, and increase the possibility for screw loosening or breakage.

The packaging that technicians use to return restorations tells a story for the dentist. Before the package is even opened, the dentist gets an idea, whether true or not, about what is inside. How much does this laboratory or technician value the work? High quality and care put into the packaging tells the dentist something special is inside, something that took great skill and training to create. Poor-quality work in a fancy package won’t fool the dentist, but the packaging should outwardly reflect the care the technician put into the craft.

Most dentists have been properly trained in implant prosthodontics, but inevitably some will not have the knowledge and skill required for the cases they send to the laboratory. They may not call to ask for the technician’s help or guidance, making it good practice for the laboratory to include a brief set of directions when returning the case to the dentists. Include the following:

Abutment material

Margin positions on the abutment (i.e., -0.5 mm facial, 0 mm lingual)

Crown material

Shade prescribed

Manufacturer suggested torque value

Screw type (i.e., 0.050 hex, 0.048 hex, unigrip)

How has the intaglio of the crown been treated? (steam cleaned, etched, silanated)

Suggested procedure sequence (i.e., remove healing abutment, insert abutment and verify fit, torque to 20 Ncm or 35 Ncm, fit crown and verify contacts and margins, obturate access hole, cement crown, clean excess cement thoroughly)

Abutment material, margin position on the abutment, crown material, and shade should have been dictated on the prescription form or discussed with the dentist before the case was started. This discussion is especially important for a dentist who may be less experienced.

The screw used to attach the abutment or crown to the patient implant should never be used in the laboratory and should remain in its original packaging. Implant screws are highly engineered to produce and maintain a specific level of tension between the implant and abutment. Many have a special coating to help ensure this happens.

When clinical screws are used during the fabrication of the restorations, they inevitably stretch (the screws and threads actually stretch), become dirty (Figure 4), and lose some coating. Some damage to the screw head may occur (Figure 5). This problem is significantly more likely to result in the screw being stripped when torqued into place. All this leads to an extremely critical component being damaged or compromised. In the laboratory, laboratory screws should be used (and reused) and not sent along with the case. The dentist may find it confusing to determine which screw is which (or it could be indicated in the directions).

It is often said that cemented crowns are nonretrievable. This is not true. To retrieve it, the clinician must drill through some sort of porcelain, metal, and/or zirconia and may not know where to drill. To make the clinician’s job easier, the technician should mark the crown where the access would need to be if removal is ever needed. Before the final glaze of the crown, estimate the access point on the crown that would allow access to the screw channel (Figure 6). Create a small divot (~0.5 mm to 1 mm) using a fine diamond bur (Figure 7). In this depression, place a highly opaque porcelain stain (such as ochre or white) (Figure 8), apply the rest of the glaze or stain as desired, and fire. The resulting crown will now have a “bulls eye,” telling all future clinicians (oftentimes not the original treating clinician) where to drill the hole should the crown need to be accessed. It’s simple and fast, and significantly improves the ease of retrievability.

Following placement, torqueing, and obturation of the screw-retained crown, the dentist will be covering the access hole with composite. Getting the composite that covers the access to have a reasonable match to the crown (Figure 9) can be challenging. Before final delivery of the crown, it is useful to have the access hole ready to be covered. I generally prefer to cover the dark metal near the occlusal with a thin layer of A1 or A3 composite opaquing resin to minimize grayness. The porcelain surrounding the access should also be beveled and etched with hydrofluoric acid. If these steps are completed preoperatively, the crown is significantly simpler and faster to deliver.

Even with the implant in the proper position, gingiva may recede. If this happens, it would be esthetically beneficial if the abutment resembled a normal root surface (Figure 10). The precolored or prestained zirconia helps minimize the “white stripe” effect. However, applying a zirconia stain to the surface to bring it down a few shades helps to significantly camouflage the abutment.

Ideally, these tips will help laboratories create stronger and mutually beneficial relationships with dentists because the little things mentioned above make treatments better for patients.

The author would like to thank Yi-Yuan Chang, MDC, for the exceptional laboratory work in Figures 6 through 8 and Figure 10.

About the author

Todd R. Schoenbaum, DDS, FACD
Assistant Clinical Professor, Division of Restorative Dentistry, Director of Continuing Education, UCLA School of Dentistry
Los Angeles, CA