The Dual-Zone Therapeutic Concept of Managing Immediate Implant Placement and Provisional Restoration in Anterior Extraction Sockets

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.^13,14 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.^15-18 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

Since not all extraction sites are the same, Salama and Salama¹⁹ 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 al²¹ 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.²³ For such compromised sites, surgical augmentation protocols^24,25 and/or orthodontic site development¹⁹ would be required to augment and reconstruct the lost hard and soft tissues prior to^26,27 or at the time of implant placement.^28,29 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.³⁰ 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.^31-34 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.^24,35 This buccal bone resorption caused by excessive buccal placement of an implant into a fresh extraction socket may exaggerate these complications.^17,36 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.^28,29

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).³⁷ 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.

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.¹² 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.³⁸ These incorporated particles provide substance to increase the soft-tissue profile.

The provisional restoration subsequently can act as a “prosthetic socket-sealing” device³⁹ 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.

A 48-year-old Caucasian female presented with an oblique root fracture of tooth No. 9 (Figure 5). The patient complained of slight swelling toward the palatal rugae area adjacent to the tooth. The periapical radiograph revealed a horizontal-oblique line coincident with the apical extent of the post-core restoration (Figure 6). An irreversible hydrocolloid impression (Jeltrate^® Alginate Impression Material, DENTSPLY Caulk, www.caulk.com) was made and an acrylic “egg-shell” was fabricated using the powder-liquid or Nealon technique.⁴⁰ Excess material was trimmed accordingly to create the finalized provisional egg shell prior to relining (Figure 7). Sharp dissection of the supracrestal fibers was performed with a 15c scalpel blade, and the tooth was removed atraumatically with extraction forceps (Figure 8 and Figure 9). Due to the fracture, sectioning of the tooth was not needed. After socket debridement with a surgical excavator, a 5-mm-diameter threaded-design, and textured-surface implant (OSSEOTITE^® Certain^® FOSS, Biomet 3i, www.biomet3i.com) was placed toward the palatal aspect of the extraction socket to a depth of 3 mm from the FGM equivalent to the mid-facial osseous crest (Figure 10 and Figure 11). It is important to note that flap elevation was not necessary for tooth extraction or immediate implant placement, and the buccal bone plate was intact after tooth removal.

The appropriate screw-retained polyether-ether-ketone (PEEK) provisional abutment (PreFormance^®, Biomet 3i) was placed using the platform-switch concept during the provisional restoration phase, which was continued through to the definitive restoration (Figure 12). The acrylic egg shell was then filled with an autopolymerizing resin (Super T, American Consolidated Manufacturing Co.), seated spatially onto the abutment in the proper facial and vertical positions, and allowed to set prior to removal (Figure 13). It is critical to place enough acrylic resin material to secure the abutment mechanically and capture the subgingival contour of the soft-tissue profile; however, this must be done without engaging the undercut regions of the proximal contact areas, as doing so would make provisional removal extremely difficult and could potentially be harmful to the implant. Therefore, a minimum torque value of 30 to 35 Ncm should be achieved upon implant placement to allow immediate provisional restoration.

The relined provisional restoration was then disinfected and placed onto a laboratory analog/replica, the proximal contact areas were marked with a red wax pencil, and the subgingival contours were re-established with resin using a sable-haired brush (Figure 14). The lingual contour of the provisional restoration was shaped with a heatless stone using a straight mandrel on a low-speed handpiece. The marked proximal contact areas, which define the buccal extent of acrylic resin removal, must be respected. Enough resin must be left palatally to keep the provisional restoration intact, stable, and secure to the PEEK abutment. Appropriate laboratory diamond burs were employed to trim the final shape/contour of the provisional restoration (Figure 15). After polishing with flour of pumice, extrinsic acrylic colorants were applied to the provisional restoration surface; it should be noted that the surface colorants should be applied only to the supragingival area of the provisional restoration (Figure 16). The provisional restoration was re-placed onto the implant and assessed clinically using the following criteria: 1) the color and form of the tooth replaced must be correct; 2) the subgingival contours must be supportive of the soft-tissue profile; and 3) the tooth must be in infraocclusion in maximum intercuspal position and lateral excursive movements (Figure 17).

It is paramount that the provisional restoration be fabricated first, prior to the placement of the bone graft material, since the graft material must remain intact and uncontaminated during the procedure. The best way to achieve this is to remove the newly fabricated provisional restoration precisely before bone graft placement.

To accomplish this, a flat-contoured healing abutment was placed onto the implant after the provisional restoration was removed (Figure 18). A xenograft bone graft material (Bio-Oss^®, Geistlich Pharma AG, www.geistlich.com) was used in this specific instance to graft the bone and tissue zones (Figure 19). The abutment must be tall and narrow enough to allow the bone graft to be placed and packed against it with an amalgam-condensing instrument up to the most coronal aspect of the FGM, thereby maximizing the amount of graft material that can be placed into the tissue zone (Figure 20). The flat-profiled healing abutment was then removed, leaving the bone graft material undisturbed (Figure 21), and the provisional restoration was successively re-placed onto the implant, tightened with finger pressure. The extruded excess bone graft material was removed to the FGM with a periodontal probe (Figure 22), and a posttreatment radiograph was taken. A periodontal curette could also have been used to accomplish this procedure.

The patient was instructed not to toothbrush the area for 3 days, and a postoperative examination was performed 1 week later. One- and 3-month follow-up visits were performed. At 5 months, a periapical digital film was taken to verify radiographic healing post-immediate implant and provisional restoration treatment (Figure 23). The provisional restoration was removed for the first time, and a healthy implant gingival sulcus was noted (Figure 24 and Figure 25). Subsequently, an implant-level transfer coping was attached for an open-tray impression, and pattern resin was used to capture the subgingival soft-tissue profile (Figure 26). A smaller diameter transfer coping (5 mm to 4 mm) was used to create a platform-switched restoration. The dental laboratory fabricated a soft-tissue cast that allowed a screw-retained gold alloy abutment for a cement-retained crown restoration to be constructed (Figure 27 and Figure 28). In order to control the correct shade of the gingival tissues and thereby eliminate the “gray effect,”⁴¹ the gold alloy abutment was gold plated (Dentsply^® Gold Plating Solution, DENTSPLY) (Figure 29). The gold-plated custom abutment was inserted intraorally, and a duplicate cementing-die replica was fabricated using a bis-acryl material (Luxatemp^® Ultra, DMG America, www.dmg-dental.com) prior to crown insertion (Figure 30).⁴² The fabrication of the cementing-die replica was done by lubricating the internal aspect of the crown, expressing the bis-acryl material into the crown, placing a metal die pin into the unset material, and then removing the die from the crown after polymerization (Figure 31). The crown could then be filled with a cementing medium (TempBond^® NE™, Kerr Dental, www.kerrdental.com) and seated on the die replica, and the excess cement removed prior to intraoral seating of the restoration (Figure 32).

The clinical strategy and benefit of this technique is to allow the indirect removal of excess cement around the final crown. This clinical step is extremely important to avoid the potential for peri-implantitis due to residual cement left in the implant gingival sulcus. The definitive crown restoration can, thus, be cemented with confidence, respecting periodontal health (Figure 33). From a three-quarter occlusal intraoral view, there was little to no clinical indication of a contour difference between the untreated tooth No. 8 versus the treated tooth No. 9 (Figure 34). The 6-month posttreatment periapical radiograph showed good bone levels around the platform-switched implant tooth No. 9 (Figure 35).

To achieve predictable esthetic success with immediate placement of implants into fresh anterior extraction sockets, the critical clinical keys that must be respected are: 1) atraumatic tooth removal without flap elevation; and 2) placement of a bone graft into the bone and tissue zones in the residual gap around an immediate fresh-socket implant, with a screw-retained provisional restoration acting as a prosthetic socket seal device. These clinical steps are helpful to limit the amount of buccal contour change of the extraction site ridge and potentially enhance the thickness of the peri-implant soft tissues coronal to the implant-abutment interface.

The authors would like to thank Mr. Adam Mieleszko, CDT, and Mr. Luis Santiago for the laboratory support in the fabrication of the restoration shown.

Stephen J. Chu, DMD, MSD, CDT
Clinical Associate Professor
Director of Esthetic Education
Columbia University College of Dental Medicine
New York, New York

Maurice A. Salama, DMD
Private Practice
Atlanta, Georgia

Henry Salama, DMD
Private Practice, Atlanta, Georgia
David A. Garber, DDS, BDS
Private Practice
Atlanta, Georgia

Hanae Saito, DDS, MS
Postgraduate Periodontology Resident,
New York University College of Dentistry
New York, New York

Guido O. Sarnachiaro, DDS
Clinical Assistant Professor
Department of Prosthodontics
Columbia University School of Dentistry
New York, New York

Clinical Assistant Professor
Department of Periodontology-Oral Implantology
Temple University School of Dentistry
Philadelphia, Pennsylvania

Private Practice
New York, New York

Dennis P. Tarnow, DDS
Clinical Professor,
Director of Implant Education,
Columbia University College of Dental Medicine,
New York, New York