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Management of Extractions for Implant Site Development

Delayed Versus Staged Implant Placement

Edentulous areas become visually unappealing when dentoalveolar bone resorbs and gingival contour collapses following tooth loss.1,2 The degree of resorption and gingival collapse depends on the quantity and quality of existing bone plus stresses on the alveolar ridge caused by prosthetic treatment and chewing. 

The objective of implant placement is to facilitate aesthetically pleasing restorations. Implants must be placed in "prosthetically driven" positions to satisfy patients' aesthetic expectations. As a result, surgical procedures for the preparation and placement of dental implants have become more complex. If sufficient bone does not exist in the dentoalveolar ridge for optimal implant positioning, bone augmentation procedures are used to develop, or regenerate, the region.

Advanced procedures such as guided bone regeneration (GBR) and bone grafting to increase the bone volume have enabled the placement of implants into prosthetically driven positions.3 Depending on the quantity, quality, and support of existing bone as well as the preferences of the clinician and patient, the placement of implants following tooth extraction can be immediate, delayed, or staged. By definition, immediate implant placement occurs at the time of extraction. Delayed implant placement is performed approximately two months postextraction to allow for soft tissue healing and closure of the extraction site. Staged implant placement allows for substantial bone healing within the extraction site and typically requires a period of six months or more.

 

Surgical Technique

In order to decide which implant placement method to employ, assess the quantity and location of bone surrounding the tooth. Once the patient has been anesthetized, use a periodontal probe to map the level of bone support through the soft tissue. Bone support that surrounds the extraction site can also be evaluated and confirmed following tooth removal by palpation, probing, and direct (internal) visualization.

If the tooth to be extracted has sufficient bone support on all surfaces, then the extraction site can be expected to fill with bone without any additional augmentation procedures (Figure 1). In this instance, a simple extraction followed by a healing period of four to six months is sufficient for complete osseous healing. An implant could subsequently be placed in the traditional manner without bone augmentation.

Conversely, if little or no bone exists on the labial surface, the site will require bone augmentation to facilitate placement of the implant (Figure 2). In this instance, bone grafting at the time of extraction can be used to maintain the alveolar ridge dimensions occupied by the tooth. The tooth is extracted using a narrow, flat instrument positioned apically into the sulcus to sever the periodontal ligament and to slightly expand the adjacent periodontal tissues. The tooth is elevated and removed with forceps using a gentle, rotational motion to prevent damaging the integrity of the labial bone. No incisions are made, and care is taken to avoid soft tissue reflection. In this manner, soft tissues maintain their structural anatomy, and the blood supply to the remaining bone remains intact.

If the tooth has multiple roots, curved roots, or other anatomical features that complicate removal, it may be necessary to section the tooth using a high-speed drill and remove it in smaller pieces. It is important to cut only tooth structure and avoid cutting (overheating) bone when using high-speed drills. The bone within the extraction site is completely debrided of soft tissue with curettes and periodontal files. Following debridement, the extraction site is thoroughly irrigated with sterile saline. At this point, bone level and support are evaluated, and a decision is made whether to graft the site and when to place the implant (immediately, delayed, or staged).

 

Case Presentation

A single-tooth implant-supported restoration was recommended to replace the right and left lateral incisors (Figures 3 and 4) in a healthy 39-year-old female patient with complete dentition. Upon clinical examination, it was determined that no labial bone support was present for the right maxillary lateral incisor. A large apical radiolucent lesion was also detected. Hence, a bone graft was needed to preserve the alveolar bone volume for implant site development and it was determined to use a conservative staged implant placement. The extraction site was grafted at the time of extraction. The alveolar bone within the extraction site was completely debrided of soft tissues with curettes and bone files. Unsupported soft tissues were easily depressed into the extraction site in a palatal direction.

Following complete debridement of all soft tissues and profuse irrigation, decalcified, freeze-dried bone allograft was placed into the extraction site. The graft material was gradually layered apicocoronally, and firmly condensed into the extraction site with an amalgam condenser (Figure 5). The central, nonporous portion of an expanded polytetrafluorethylene (e-PTFE) barrier membrane was cut to a size that was slightly larger than the extraction site opening. The inner cell-occlusive aspect of the membrane was used so that the graft material would be protected. This barrier serves to delay, but not to prevent, the soft tissues from entering the protected site. The custom fit cell-occlusive barrier was placed over the graft material. The barrier was placed between the gingival connective tissues and alveolar bone or graft material. Care was taken to gently suture the barrier membrane over the graft material into the adjacent gingival tissues (Figure 6). The bone graft was allowed to heal for six months prior to implant placement. An acrylic provisional restoration was fabricated, adjusted to fit the edentulous space, and resin bonded with titanium mesh reinforcement between teeth #6 and #8.

The right lateral incisor site healed without complications. The suture became loose and was removed four weeks postoperatively. The barrier membrane was covered by soft tissue and remained in place for the entire six-month healing period (Figure 7).

The patient then decided to have the left maxillary lateral incisor removed and replaced with an implant-supported restoration. Examination revealed that although adequate interproximal bone support was evident, bone was absent from the labial surface of the left lateral incisor. A bone graft was indicated for this site to preserve the alveolar bone volume for implant site development. In order to place both implants simultaneously, however, a delayed implant placement was planned. The left maxillary lateral incisor was extracted using atraumatic surgical techniques (Figure 8). No incisions were made and care was taken to avoid any soft tissue reflection. The alveolar bone within the extraction site was debrided of soft tissues, irrigated well, and allowed to heal for two months. No bone graft or other material was placed into the site at the time of extraction.

The placement of implants for both sites was simultaneous. The right lateral incisor site, with the bone graft, healed for eight months (staged placement) and the left lateral incisor site, without a bone graft, healed for two months (delayed placement). A surgical guide was used to place machined, self-tapping implants in a position that would be optimally suited for subsequent prosthetic treatment (Figures 9 and 10).

The staged approach for the right incisor resulted in the development of a site with adequate bone volume and complete implant coverage (Figure 11). The delayed technique for the left, however, resulted in a site that exhibited soft tissue coverage and an inadequate bone volume with a significant labial dehiscence that exposed eight screw threads (Figure 12). A nonresorbable (e-PTFE) barrier membrane was used to promote guided bone regeneration (Figure 13). Both sites were completely covered with soft tissue flaps and sutured without tension.

The sites healed without complication for an additional six months. Both lateral incisor sites maintained proper soft tissue ridge height and volume relative to the adjacent interdental papilla (Figures 14 and 15). Second-stage surgery was performed on the staged site with a minimally invasive flap design that preserved the interdental papilla (Figure 16). The left lateral site required a slightly more extensive flap design and reflection in order to remove the barrier membrane (Figure 17). Under the barrier membrane, firm tissue completely covered the previously exposed implant. Healing abutments were placed and the implants were subsequently restored with single-tooth porcelain-fused-to-metal crowns with abutments (Figures 18-19-20). The preservation of alveolar bone with conservative techniques and the prosthetically driven implant placement allowed for screw-access within the normal contours of the crown in the cingulum area. Composite resin was used to cover the screw-access holes.

 

Conclusion

The position and angulation of dental implants has become increasingly important to the aesthetic and functional result of the implant-supported dental prosthesis. Proper placement depends on the quantity and location of alveolar bone. Tooth loss or simple extractions without grafting or implant placement often result in bone-volume deficiency and aesthetic concerns. In the maxillary anterior region, teeth often have very thin or nonexistent labial bone that, following extraction, has a tendency to collapse in a palatal and apical direction via resorption and lack of support. This collapse results in a deficient dentoalveolar ridge that is inadequate for prosthetically driven implant placement.

This case documents two conservative approaches to the management of extractions that facilitate the preservation of bone for prosthetically driven implant placement. The delayed and staged techniques for implant placement presented in this article reduce the need for additional bone augmentation procedures and eliminate the need for mucogingival procedures. Each has advantages that can be used for specific situations while maintaining adequate alveolar bone volume for ideal implant placement and aesthetics.

*Private Practice, Los Angeles, California

 

References

  1. Johnson K. A study of the dimensional changes occurring in the maxilla following tooth extraction. Aust Dent J 1969;14(4):241-244.
  2. Johnson K. A study of the dimensional changes occurring in the maxilla following closed face immediate denture treatment. Aust Dent J 1969;14(6):370-376.
  3. Shanaman RH. The use of guided tissue regeneration to facilitate ideal prosthetic placement of implants. Int J Periodont Rest Dent 1992;12(4):257-265.
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