A Customized Healing Abutment for Immediate and Delayed Implant Cases

Bone-level dental implants are anchored in bone. The crown or abutment attached to the implant transverses through the soft tissues. The natural tooth defines the shape of the surrounding soft tissues. Upon removal of the tooth, the soft-tissue contour begins to change immediately. Initially, this is because support is lacking; but soon after, the biologic cascade of the healing process remodels the tissue composition and contours. The healing process of the underlying bone reduces the overall bony support for the soft tissue that covers it.^1-3

To create a natural appearance of a dental implant reconstruction, it is imperative that the original soft-tissue contours be maintained or reconstructed. Various hard- and soft-tissue augmentation techniques have been described.^4-7 In addition, it appears that a properly constructed provisional crown or healing abutment can add to the stability and maintenance of the soft-tissue contours in both immediate sites^8-14 and healed sites.^15-17 While titanium and zirconia are commonly considered preferential materials to interface with the soft tissues^18-20 other materials also have been used.^21-23 The use of zirconia and titanium requires the use of CAD/CAM technology,^24-26 whereby acrylic and composite resin can be processed in an analog fashion. Chu et al described an innovative polymethyl methacrylate prosthetic shell that mimics the contour of the root of the tooth, which is replaced in an immediate technique with a dental implant.^27,28 This approach allows the soft tissues to heal with a similar support structure as was previously provided by the root surface while containing the graft material that is used.

This article aims to describe related techniques that will allow chairside manufacturing of custom healing abutments for both immediate-placement and healed sites. In addition, the method allows for orienting the abutments in a pre-designed 3-dimensional (3D) position. The use of a vinylpolysiloxane (VPS) cast facilitates chairside fabrication.

A 75-year-old female patient presented with a failing lower left first molar. A diagnosis of root fracture and periapical abscess was appropriate. Cone-beam computed tomography cross-sectional imaging showed adequate healthy bone above the mandibular canal, which would allow for the securing of a dental implant in an immediate placement protocol.

A fully restrictive surgical guide (3D Click Guide, Idondivi, Inc., 3dclickguide.com) was fabricated based on an irreversibly hydrocolloid alginate impression (Cavex Impressional, Cavex Holland BV, cavex.nl). The same impression was used to cast a partial section in a dedicated casting VPS (Mach-SLO™, Parkell, parkell.com). The tooth to be extracted was identified, the contours were marked with pencil, and the coronal section was cut with a scalpel (Figure 1). A tapered diamond drill was used to cut a 2.5-mm-deep well following the exact outline as the molar (Figure 2 and Figure 3). A flowable composite resin (Tetric EvoFlow^®, Ivoclar Vivadent, ivoclarvivadent.us) was used to fill the prepared well. This mass was light-polymerized.

After the composite resin set, four wings 2 mm to 3 mm in length were placed over the buccal and lingual gingiva, connecting the composite mass (Figure 4). The central part of the rootform composite was removed with a diamond drill. The tooth was extracted, and the implant (NobelActive 4.3 x 13, Nobel Biocare, nobelbiocare.com) placed, as previously planned. The rootform unit was positioned into the extraction socket, to which it readily adapted. The wings allowed seating orientation (Figure 5).

A temporary titanium cylinder was attached to the implant, and the rootform shell was placed over it in the correct position and secured with a flowable resin composite material. The assembly was removed from the mouth, and additional composite resin was applied to create a smooth transition between the titanium cylinder and the composite shell. The titanium sleeve was then shortened. A slow-resorbing bone substitute material (Bio-Oss^®, Geistlich Biomaterials, geistlich-na.com) was placed in the space around and above the implant, and the healing abutment was placed (Figure 6). The healing abutment contained the graft material, much like a cork on a wine bottle contains the wine (Figure 7).

Healing was uneventful, and it is important to note that the initial contour appeared to have been maintained (Figure 8). After 4 months, osseointegration was confirmed with an implant stability quotient (ISQ) reading of 83. Upon removal of the healing abutment it was evident that the bone substitute particles had incorporated into the soft tissue while the original contour had been maintained (Figure 9). Graft particles were visible, as per the concept of the dual-chamber grafting technique as described by Chu and Salama et al.^8,9 A custom impression coping allowed the transfer of the subgingival contours. The screw-retained crown showed a natural contour of the soft tissues (Figure 10) with an emergence that mimicked the natural root shape contours, which will reduce the occurrence of food impaction (Figure 11).

A 74-year-old female patient had lost her lower left first molar due to nonrestorable extensive decay. The tooth was extracted and the site was allowed to heal. After 4 months a fully restrictive surgical guide (3D Click Guide) was made using an irreversibly hydrocolloid alginate impression (Cavex Impressional).The same impression was used to cast a local section with a fast-setting dedicated casting VPS (Mach-SLO). An outline was drawn signifying the desired contour of a replacement crown, limited by the bucco-lingual dimension of the residual ridge. A 2.5-mm-deep well was cut out with a slightly tapered diamond bur. The created well was filled with light-polymerizing flowable composite resin (Tetric EvoFlow).

After polymerization of the composite resin a non-setting moldable plastic compound (Model Bloc™, TAK Systems, taksystems.com) was applied to eliminate the undercuts at the adjacent teeth. Flowable resin was syringed onto the occlusal surface of the adjacent teeth, and the occlusal rests were connected to the composite in the well. Upon polymerization the unit was removed from the VPS cast and a central hole was cut using a diamond.

Clinically, a papilla-sparing incision was made, with reflection of the flap toward the buccal. The winged rootform shell was then placed over the titanium healing abutment after the implant was placed (NobelActive 4.3 x 8.5). Bone was removed as needed to allow for unobstructed seating of the abutment shell. Seating was confirmed by the passive resting of the orientation wings onto the occlusal surface. Flowable composite resin was applied to connect the shell with the provisional titanium cylinder (Figure 12). After removal of the assembly from the mouth, the flowable composite resin was added to create a smooth transition and the titanium sleeve was shortened.

The healing abutment was placed (Figure 13 and Figure 14). The buccal flap was de-epithelized with a diamond bur, rotated over itself, and sutured so as to bring a significant volume of attached tissue toward the buccal. After 6 weeks of healing the implant was integrated as evidenced by an ISQ of 76. The soft-tissue contours were consistent with the ideal shape for a molar crown (Figure 15). Emergence from the gingiva closely mimicked the original root shape, aiming to reduce food impaction complications.

An implant is circular, but the cross-section of any tooth is not. Standard healing abutments also are circular and create a circular soft-tissue contour upon healing and accommodate maturation of the soft tissues. To create esthetically pleasing restorations, it is desirable that soft-tissue contours closely resemble those of healthy teeth. From a functional perspective interproximal areas among implants that are much the same as natural teeth will lessen the incidences of food impaction compared to open embrasure spaces.²⁹

In addition, interpretation from early research appears to show that a properly contoured healing abutment or crown may be able to protect slow-resorbing bone substitution materials and allow them to mature.^8,9 Augmentation of bone and soft-tissue volumes can be obtained using this combination of a graft and prosthetic graft protector. Idealizing soft-tissue contours early in the healing process will greatly facilitate the restorative phase.

The technique described allows for simple extraoral, chairside fabrication of customized healing abutments while minimizing the contact of uncured composite resin with the peri-implant soft-tissue wound. It also allows for improved curing of the custom healing abutment material without the influence of contaminants from the wound, which would further compound the biological negative effects of using composites.³⁰

The authors had no disclosures to report.

Lambert J. Stumpel, DDS
Private Practice, San Francisco, California

Chandur Wadhwani, BDS, MSD
Private Practice, Bellevue, Washington