The success of all-on-four type hybrid restorations has been well established in recent years and yet the options and case criteria are so varied, creating a standardized protocol is difficult. The number of implants, AP spread, and angulation are certainly a key factor, along with the vertical clearance. We have a great program already prepared and will come to your local area for a study club presentation this fall. Until then, here are a few case planning thoughts we hope nearly everyone can agree on.
With just two implants, use locators (or similar system) and a full denture with metal base. The implants can be divergent by 30 degrees. Vertical height requirement over the locators should be at least 8 mm. Lab fee is $1,235 plus $295/locator.*
Fixed Detachable Acrylic Hybrid
With four or more implants, a good AP spread, and 15 mm of occlusal clearance, a Screw-Retained Acrylic Hybrid with bar is an excellent option. We use only milled chrome-cobalt bars which improves the strength by 30%, so we can go down to 12 mm if necessary on some cases. Most labs use cheap milled titanium bars or even worse, they cast them in house which is about half the strength necessary for long term success. We can also include a spare milled prototype for the patient to use if adjustments to the final hybrid are ever necessary. Lab fee is $3,995 complete.*
When considerable soft tissue is missing and/or the implants cannot be made parallel with uni-abutments, consider a bar-overdenture. Vertical stops and lateral stability are achieved with the milled bar and cast partial. Direct retention can be achieved with stud/ball attachments on the bar, or a locking fixed detachable type system like the Lew attachment. This bar partial technique would require at least 10 mm of vertical height. Lab fee is $3,995 plus attachments.*
Conus Crown & Sleeve Type Overdenture
The Conus option requires four implants with reasonable AP spread and 10 mm vertical height. Non-parallel abutments can be corrected up to a total of 30 degrees. Precision abutments with friction fit sleeves are made and incorporated into the denture with a metal base. The denture is implant supported and retained. It is removable by the patient for cleaning, but extremely solid and retentive when seated. Lab fee is $1,235 plus $400 per Conus abutment.*
Implant Supported Fixed Dental Prosthesis (ISFDP)
…or the Prettau type all zirconia implant bridge has become very popular in recent years. It can be reduced in vertical height to as little as 8-10 mm in some cases. The lower bridge is usually kept full contour for maximum strength. This restoration usually requires
uni-abutments to correct and idealize screw access holes. Upper cases are usually cut back on the facial and custom layered. The protocol for a full arch zirconia bridge requires the additional step of PMMA prototypes, which are adjusted in the mouth and used to “copy mill” exactly in the lab for the final restoration. The implant supported implant bridge is a more costly, and time consuming protocol which should be reflected in your fees. Lab fee is $300/unit plus $395/implant. Two prototypes are also required which will cost $900 plus parts.*
Other Hybrid Options
There are times, especially on the mandible, when other options are needed. For example, opposing zirconia implant supported bridges are contraindicated for some patients. Also, when implants are placed posterior to the mental foramen, mandibular flexure can sometimes be a concern. A less rigid option is desirable when the TMJs are bone-to-bone such as with Piper 5a or 5b joints. For these and other considerations, we occasionally have to look at options involving some of the newer generation materials. These synthetic bone type materials are more difficult to process but offer less abrasive and slightly more resilient properties. These product options are in-house and available as needed.
*prices as of published date