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 »  Home  »  Dental Implant 2  »  Provisional Implants: Surgical and Prosthetic Aspects
Provisional Implants: Surgical and Prosthetic Aspects
Introduction.

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Charles A. Babbush, DDS, MScD
Director, The Dental Implant Center, Lyndhurst, Ohio.
Director, Dental Implant Research, and Clinical Professor, Case Western Reserve University, School of Dentistry, Cleveland, Ohio.


Over the past quarter century, dental implant reconstruction has become a highly efficient, predictable modality. The ability to accurately assess bone quality and quantity has greatly simplified the treatment-planning process. Computed tomography scanning technology with three dimensional reformatted imagery and related software, such as Sim/Plant (Columbia Scientific Inc., Columbia, MD) and Digital Radiography (Radiovisiography Trophy Inc., Danbury, CT), have added to our ever-increasing diagnostic armamentarium.
Other programs, such as Consult-Pro (Nobel Biocare, Yorba Linda, CA), have enhanced the implant practitioner’s ability to educate patients about the implant process. This, in turn, leads to a more thorough informed-consent process. Once cases are in progress, follow-up in a database can now be easily managed with software such as The Implant Tracker (Nobel Biocare).
Compromised anatomical deficiencies can now be augmented and grafted with state-of-the-art allograft materials, such as Dynagraft (GenSci, Irvine, CA), and a variety of guided bone-regeneration materials (W.L. Gore, Flagstaff, AZ). Improved instrumentation, such as the Osteoharvester (Osteomed Corp., Addison, TX), has also enabled doctors to harvest autogenous grafts with greater ease, improved benefit/risk ratios, and more favorable long-term outcomes. The ability to generate autogenous growth factors by harvesting patient blood in small (55–110 mL) batches and rapidly producing platelet concentrate with an office-based closed system (Harvest Technologies Corp., Norwell, MA) has dramatically decreased the need for second-site bone harvesting and improved the quality of the implant site and shortening overall treatment time.
Amid all this progress, certain areas have demanded further improvement. One such area relates to the understandable desire of patients to have teeth during the immediate postoperative period. To address this need, Jack Wimmer of Park Dental (Park Dental Studies, New York, NY) introduced temporary or provisional implants in the form of the Lew Screw in the 1970s. Victor Sendax later developed the Sendax Mini-Dental Implant System (U.S. Patent No. 5,749,732, Imtec Corp., Ardmore, OK), and the work of Paul Petrungaro with the Dentatus System (Dentatus AB, Hagerten, Sweden) along with that of numerous other clinicians further extended this concept.
The immediate provisional implant system (Nobel Biocare, Göteborg, Sweden) simplifies the process of delivering a stable, temporary fixed prosthesis at the time of implant placement. It eliminates the need for a temporary tissue-borne prosthesis that can damage conventional submerged implants and/or accompanying bone grafts. Instead, the immediate provisional implantsupported prosthesis removes the load from the soft tissue over the conventional implants and/or bone graft sites. This allows for improved healing and provides the patient with an esthetic, functional, provisional prosthesis.
The immediate provisional implants are designed with a 2.8-mm diameter at the shoulder and are supplied in 14-mm lengths; however, the length can easily be shortened by using a small pin cutter or a disk. Fabricated from titanium alloy for strength, the one-piece implant body is threaded and has a smooth machine finish. The design of the implant allows it to be bent at the neck to an angle of up to 45 degrees (a limit that far exceeds any foreseeable clinical requirement). Adjustment can thus be made for parallelism between one implant and another.
The abutment head has a fivedegree taper, an ideal configuration for cementable prostheses. A flat side on the abutment head facilitates proper placement and orientation of the insertion and removal instruments, transfer coping, and alignment of the analog in the master model if required.
The immediate provisional implant system contains all the instrumentation necessary for preparing the osseous receptor sites as well as inserting, removing, aligning, and achieving parallelism of the implants. Only one drill, a disposable 1.5-mm twist drill, is required for placement of the implants. The tooling also includes an insertion wrench, a hand wrench, a ratchet adapter, a ratchet arm, paralleling pins, a bending tool, a retrieval tool, and a stabilizing instrument for bending.
The immediate provisional implants are placed after the regular implants are in position. In the fullarch mandible, the manufacturer recommends the use of four or more immediate provisional implants. In the full-arch maxilla, a minimum of five immediate provisional implants is recommended. In small-segment situations, two to three immediate provisional implants should be used. Each of the immediate provisional implants should be placed between 1.5 mm and 2.5 mm from the adjacent conventional implants.
When the depth of available bone is ,14 mm or the amount of cortical bone is insufficient to provide stabilization, the immediate provisional implant may be contraindicated. Immediate provisional implants should not be used when it is not possible to place a sufficient number to provide adequate support for a temporary prosthesis. If the immediate provisional implant is shortened because of a lack of vertical bone, the bioengineering of the case should be reviewed and consideration given to inserting an additional implant( s) to add to the overall support.