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20 Mar 2017

By Stephen J. Chu, Maurice A. Salama et al

[periodontal, implants]

The dual-zone therapeutic concept of managing immediate implant placement and provisional restoration in anterior extraction sockets

Salama - Dual Zone.png

 

ABSTRACT

Improvements in implant designs have helped advance successful immediate anterior implant place­ment into fresh extraction sockets. Clinical techniques described in this case enable practitioners to achieve predictable esthetic suc­cess using a method that limits the amount of buccal contour change of the extraction site ridge and potentially enhances the thickness of the peri-implant soft tissues coronal to the implant-abutment interface. This approach involves a traumatic tooth removal without flap elevation, and placing a bone graft into the residual gap around an immediate fresh-socket ante­rior implant with a screw-retained provisional restoration acting as a prosthetic socket seal device.

 

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For more than two decades, the clinical protocol for immediate anterior implant placement into fresh extraction sockets has evolved from a two-stage protocol with full-thickness flaps to a one-stage protocol—often flapless and some­times with an immediate provisional restoration placed at the same appointment without compromising implant survival rates. This evolution was facilitated by improve­ments in the macro- and micro-geometry of implant designs and their re­spective restorative components as well as validation from animal and human clinical research.

The ongoing challenge for clinicians utilizing immediate anterior implant placement protocols today is no longer just achieving osseointegration, the rates of which are extremely high. Instead, the challenge is improving on protocols that allow for less traumatic, more time-efficient and yet highly predictable esthetic treatment outcomes in the more demanding anterior region. The main determinants to achieving long-term esthetic predict­ability in this environment are related to understanding and managing a complex combination of clinical and biologic factors, as follows:

 

  1. Diagnosis and classification of the extraction site in the esthetic zone
  2. The natural biologic modeling and remodeling of extraction sockets
  3. The relationship of underlying bone to the overlying soft-tissue profile and their stability
  4. The relationship of labial and vertical soft-tissue thickness and height around implant-supported restorations
  5. Site-specific surgical protocols that minimize negative dimen­sional alteration of the site
  6. Restorative protocols and materials that optimize healing as well as soft-tissue stability and color

 

Diagnosis and classification

 Since not all extraction sites are the same, Salama and Salama as well as Elian et al20 suggested extraction site classification schemes that were meant to be utilized in developing site-specific treatment designs based on gingival margin level as well as the presence or absence of the labial and interproximal bone sur­rounding the compromised tooth to be extracted. Tarnow et al and Salama et al22 demonstrated the direct relationship of the po­sition of the interproximal bone surrounding a tooth or implant, respectively, to the location and shape of the overlying papilla. Where deficiencies existed in any of the criteria listed above, they would be classified as Type II or Type III sites, depending on severity. For such compromised sites, surgical augmentation protocols and/or orthodontic site development19 would be required to augment and reconstruct the lost hard and soft tis­sues prior to or at the time of implant placement. However, whenever the extraction socket is not compromised—with an esthetically acceptable mid-facial gingival margin position and a completely intact labial plate and interproximal bone levels—a Type I classification is rendered, demanding an emphasis on hard- and soft-tissue preservation protocols.

 

When a tooth is extracted, the dimensional change of height and width of the alveolar ridge will occur. The reduction of the height of the bony wall is more pronounced at the buccal than lingual aspect of the extraction socket. This correlates to the amount of vertical loss of bone height, which is also more pro­nounced on the buccal wall. It has been well documented that major contour changes of the alveolar process take place dur­ing the first 6 months following tooth extraction. This results in the reduction of the width of the alveolar ridge and the vertical height. This reduction interferes with the placement of dental implants and influences the success of the prosthesis with re­gard to esthetics. If the implant is not placed more to the palatal aspect and apical in the extraction socket to assure the proper emergence profile, the optimal esthetic outcome may be compro­mised. This buccal bone resorption caused by excessive buccal placement of an implant into a fresh extraction socket may exag­gerate these complications. These esthetic complications are emphasized in patients with a thin periodontal phenotype, and an additional surgical intervention may be required to remediate the surrounding soft-tissue architecture before, during, or after implant placement.

 

The dual zone is divided into two regions: the tissue zone and bone zone. The tissue zone is the labial-palatal dimensional change of the vertical region of tissue defined as ranging from the free gingival margin (0 mm) to the labial crest of bone mid-facially (Figure 1 and Figure 2). The bone zone is the tissue apical to the os­seous crest (Figure 3 and Figure 4). After tooth removal, implant placement, bone grafting, and provisional restoration, the contour of the ridge can change. This article provides a clinical example of a case that illustrates the use of these techniques to minimize contour change associated with immediate anterior implants.

 

 

 Fig 1.pngFig 2.png

 

 Fig 1 and Fig 2. The tissue zone is defined as the tissue coronal to the implant-abutment interface. Contour change and thinning of the peri-implant tissues in this zone can lead to tissue discoloration due to abutment shine-through effect.

 

 

Fig 3.pngFig 4.png

Fig 3 and Fig 4. The bone zone is defined as the tissue apical to the implant-abutment interface. Contour change in this zone due to ridge collapse can lead to tissue discoloration below the head of the implant due to shine-through of the implant body.

 

 

Fig 5.png

Fig 5. Intraoral pretreatment condition of tooth No. 9, which had a horizontal-oblique fracture of the tooth toward the palatal aspect.

 

 

Fig 6.png

Fig 6. Periapical radiograph of tooth No. 9 showed a horizontal root fracture and distal open margin of the crown restoration.

 

 

Fig 7.png

Fig 7. An acrylic “egg shell” using the Nealon technique was made and relieved on the palatal aspect maintaining the proximal contact areas and incisal position to allow complete seating over a screw-retained implant abutment.

 

Fig 8.png

Fig 8. Sharp dissection of the supracrestal attach­ment fibers was performed with a 15c scalpel blade. The intrasulcular incision was made 360 degrees around the tooth. Tooth removal must be performed without flap incision or elevation.

 

Fig 9.png

Fig 9. The proper size and shaped forceps was used to atraumatically remove the fractured root fragments.

 

Fig 10.png

Fig 10. After thorough socket debride­ment and verification of an intact buccal plate, a 5-mm diameter threaded implant was placed to the palatal aspect of the extraction socket, leaving a buccal residual gap distance of about 2 mm.

 

Fig 11.png

Fig 11. The implant-abutment interface was placed in a vertical spatial posi­tion coincident with the mid-facial crest of bone equivalent to the normal dento-gingival complex.

 

Surgical and restorative-specific tissue preservation protocols

The most critical surgical strategy for immediate implant place­ment and provisional restoration is atraumatic tooth removal without flap elevation—especially in the esthetic zone, where the buccal bone plate and soft tissues are thinnest in buccal-palatal dimension. The rationale for this procedure is to maintain the remaining blood supply from the periosteum and endosteum for maximum healing potential; the periodontal ligament is the third blood supply that is eliminated during tooth removal. If necessary, any of the anterior six teeth can be sectioned bucco-lingually with a surgical-length bur to achieve atraumatic removal without trauma to the buccal plate. The implant should be placed palatally and 3 mm to 4 mm apical to the free gingival margin (FGM) to optimize esthetics. Autogenous, allograft, xenograft, and synthetic bone re­placements, substitutes, and/or materials can be used in the gap to graft the bone and tissue zones, respectively. The graft material helps serve as a scaffold to maintain hard- and soft-tissue volume as well as blood clot for initial healing. A recent article by Araújo, Linder, and Lindhe suggested that a xenograft material can be used in the gap and the particles can be incorporated into the soft-tissue profile without any inflammatory reaction. These incorporated particles provide substance to increase the soft-tissue profile.

 

The provisional restoration subsequently can act as a “pros­thetic socket-sealing” device to protect, contain, and maintain the blood clot and bone-graft material during the healing phase of treatment. Table 1 outlines the treatment sequence and ac­companying procedure for this clinical technique.

 

Treatment Sequence and Corresponding Appropriate Procedure for Immediate Implant Replacement, Bone Grafting, and Provisional Restoration  

 

Treatment sequence

Treatment procedure

Fabricated provisional restoration acrylic egg shell

Make an irreversible hydrocolloid impression of tooth and paint-in  acrylic resin using the “Nealon” technique.

Atraumatic tooth removal

Sever supracrestal fibers with 15c scalpel blade and extract tooth  with appropriate forceps. Section the tooth (bucco-lingually for  canine to canine; mesio-distally for first bicuspid) if necessary.  

Clean residual debris from extraction socket and examine the socket

Use surgical spoon excavator or curette. Check for intact buccal examine the socket plate (no more than 4 mm apically from FGM).  

Spatial implant placement

Palatal placement within socket with implant head coincident or  slightly apical to buccal osseous crest (3 mm to 4 mm from FGM).  

Fabricate screw-retained provisional restoration

Place screw-retained provisional abutment and transfer tooth- formed shell with either acrylic resin or flowable composite,  capturing the shape and contour of the residual extraction socket.  

Place bone graft material Remove fabricated provisional restoration

Place a long flat healing  abutment, and pack bone graft material into bone and tissue zones,  respectively, between implant and buccal wall of the socket up to  the FGM.  

Re-insert provisional restoration

Provisional restoration acts as a prosthetic socket “seal” to protect, contain, and maintain blood clot plus bone graft material during the healing period of 4 to 6 months.  

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