Success With Interdisciplinary Dentistry: Immediate Implant Treatment in the Aesthetic Zone

INTRODUCTION
Immediate implant treatment in the aesthetic zone is a challenge due to the need for a biologically compatible, functionally compliant, and aesthetically pleasing result.^1-3 Immediate implant placement following extraction has been well documented to preserve the architecture of the peri-implant gingiva.^4-8 This is of critical importance in cases involving thin gingival biotypes with highly scalloped papilla which are highly susceptible to recession during or following treatment.⁹ Proper management of the periodontal complex is a key component of successful implant treatment in the aesthetic zone.^10-13

The selection of abutment type and material plays a critical role in the success of anterior implant treatment. Uncoated titanium abutments can cause a graying effect on the gingival color and the final shade of an all-ceramic crown. UCLA (screw-retained) abutments allow the porcelain to be carried very close to the head of the implant and prevent any complications with retained subgingival cement, but require that the screw access be concealed palatal to the incisal edge. There is also evidence to suggest that the gold alloy at the head of the implant may lead to a one-mm apical repositioning of the peri-implant bone when compared to titanium and zirconia¹⁴ (there is, however, evidence to the contrary as well¹⁵). Custom-made zirconia abutments allow for idealized placement of the crown margins (thus minimizing the risk of retained subgingival cement),¹⁶ and minimize some of the graying effect on the gingiva. Zirconia abutments do, however, carry a minor increased risk for breakage compared to titanium and gold alloy abutments. As such, their use and design should be carefully considered for treatment involving higher anticipated loads.¹⁷

Shade matching a natural dentition with complex characterization is difficult under normal circumstances. It is a task made even more challenging when one restoration is for a natural tooth preparation and the other for an implant. Properly calibrated photography can assist the clinician and the ceramist in clearly communicating the shade and characterization of the natural dentition to be matched in a way that no drawing or shade tab can.^18-20

As they have increased in popularity, there have been an increasing number of reported problems with cement-retained implant crowns, particularly related to peri-implant inflammation, recession, and bone loss secondary to retained cement subgingivally.^21-23 It is likely that many of these failures could have been prevented with a few minor changes: peri-implant gingiva that has been allowed to mature for at least 3 months, a custom-designed abutment that fills the subgingival space completely, abutment margins placed no deeper than 1.0 mm subgingivally, and the use of a semi-soluble cement.²⁴ Many of the peri-implantitis cases caused by retained cement involve the use of inappropriately selected stock abutments (or tissue-level implants) that have their margins far too deep subgingivally,²⁵ thus compromising even the most diligent efforts at cement removal. The use of resin-based cements on implant restorations is also problematic because they are nearly insoluble in the oral environment and significantly more difficult to remove compared to glass ionomer (GI)-based cements.²⁶

CASE REPORT
Diagnosis and Treatment Planning
A 69-year-old female presented with the upper left lateral incisor fractured approximately 3.0 mm below the free gingival margin. In addition, the upper right lateral incisor presented with large failing composite resin restorations and failing endodontic treatment (Figure 1). Her gingival biotype was thin, with a highly scalloped architecture. Probing depths of adjacent teeth ranged from 2.0 to 4.0 mm. Interproximal bone levels adjacent to the proposed implant placement in the upper left lateral incisor were ideally positioned to maintain the gingival papilla adjacent to the implant. The CBCT scan revealed 7.5 mm of space mesio-distally at the bone crest and an intact facial bone plate. The patient had a high smile-line that revealed 2.0 to 3.0 mm of the gingiva at both lateral incisor positions.

Figure 1. A 69-year-old female patient presented for treatment of catastrophic fracture of upper left lateral incisor. She had a high lip-line, and highly scalloped, moderately thin gingival biotype.

Figures 2a and 2b. (a) Upper right lateral incisor was stabilized with retreatment of the root canal system and replacement of the leaking coronal restorations. The upper left lateral incisor was extracted, and (b) a standard-diameter implant was immediately placed in a one-stage approach with a short, straight healing abutment.

Figures 3a and 3b. (a) Emergence of the custom-milled zirconia abutment was deemed to be insufficiently supporting the distal papilla. (b) The contour was corrected through the addition of the appropriate feldspathic porcelain. This would help ensure support for the thin distal papilla.

Figure 4. Use of an alveolar (“Geller-type”) cast assisted the technician in properly supporting the gingiva in a way that is difficult with the use of the silicone soft-tissue masks commonly used in implant model work.

Figure 5. The technician built the dentin layers of the prostheses using the same porcelain to minimize difficulties in matching shades between a natural tooth abutment and the zirconia abutment.

Figures 6a and 6b. Trial fitting of the prostheses with glycerin revealed that the first set was both (a) too low in value and (b) too blue in hue. Restorations were remade using information from these 2 photographs.

The authors jointly determined that the most appropriate treatment would be to extract the upper left lateral incisor and immediately place a standard-diameter, internal connection implant using a flapless, single-stage approach. The upper right lateral incisor would be retained, the root canal retreated, and restored with a full-coverage restoration (with cingulum preservation). The patient opted to forego having a provisional restoration for the implant.

Clinical Protocol
The upper left lateral incisor was atraumatically extracted, the socket was degranulated, and the clinical examination revealed that all bony walls were intact except for a small fenestration in the buccal plate about 6.0 to 7.0 mm below the alveolar crest. The site was carefully prepared, and a tapered implant (Nobel-Replace, RP 4.3 mm x 13 mm [Nobel Biocare]) was placed at the apico-palatal aspect of the socket with a line of draw slightly palatal of the proposed incisal edge. The open gap of the extraction socket space between the implant and the facial bone was grafted with freeze-dried bone allograft (AlloGraft GC [Straumann USA] 0.25 cc, Mineralized Ground Cortical [Straumann USA/Lifenet Health]), which occluded the fenestration as well. A straight, 3.0-mm tall healing abutment was placed (Figure 2). A crescent-shaped gingival graft was harvested from the left palate (adjacent to premolars) and placed over the bone allograft, sutured to surrounding soft tissues to contain the bone allograft to enhance labial soft-tissue thickness.²⁷

Healing was uneventful and the tissue response was positive. As expected, without the aid of a provisional restoration with supportive proximal contours, there was a slight flattening of the papilla at the mesial and distal initially, though there was significant circumferential growth of the gingiva over the coronal portion of the abutment. Seven months after implant placement, the impression and shade selection were made. Extensive photographic documentation was used to convey the complex internal and external anatomy of the adjacent dentition to the ceramist. The upper right lateral incisor was prepared for a full-coverage porcelain restoration with preservation of the cingulum to minimize weakening the tooth.²⁸ At the time of preparation, the tooth was etched and coated with bonding agent (SELECT ETCH HV; ALL-BOND 3 [BISCO Dental Products]) to increase long-term bond strength.

Figure 7. The emergence zone of the custom-milled zirconia abutment was coated with petroleum jelly prior to seating in order to minimize the potential for cement retention on the abutment. The margins of the abutment were prescribed to be placed 1.0 mm subgingivally on the facial and equigingivally on the palatal. The margin of the upper right lateral incisor was not extended to the free gingival margin as a “creeping reattachment” of the gingiva and was expected to extend over the exposed root surface.	Figure 8. Evaluation at 18 months following delivery of the definitive restorations on the lateral incisors revealed improvement in the gingival positions on the restored tooth and implant. However, the patient’s improved gingival health and resolution of mild inflammation resulted in opening the gingival embrasure between the unrestored central incisors.
Figure 9. The papillae adjacent to the implant responded well to the contours of the abutment and the position of the implant, resulting in a satisfactory soft-tissue height and volume. The zirconia abutment minimized the color change to the color of the thin overlying gingiva.	Figure 10. The mid-facial gingiva responded favorably to the supragingival margin placement and improved oral hygiene, resulting in approximately one mm of coronal migration (note previous position in Figure 7).

Figures 11a and 11b. Post-op radiograph reveals (a) stable peri-implant bone levels and (b) healing of the peri-apical radiolucency following root canal retreatment.

The authors determined that use of a custom zirconia abutment was appropriate because of the patient’s high smile-line, thin gingival biotype, and apparent low functional load at the lateral incisor. The abutment was designed and fabricated using CAD/CAM (Procera [Nobel Biocare]). It was determined that in its initial form, the abutment was lacking the volume necessary to support the distal papilla (Figure 3a). This open subgingival space was filled by fusing porcelain (VITA VM 9 Effect Liner 1 [VITA North America]) to the abutment (porcelain with an appropriate coefficient of thermal expansion for zirconia [25°C to 500°C, 9.0 to 9.210-6m/m K] was used for this purpose) (Figure 3b). The evaluation of the peri-implant space was aided by the fabrication and use of a “Geller-type” cast (Figure 4) that preserved the soft-tissue contours around the implant and natural teeth. The margins of the abutment were designed to be one mm subgingival at the facial, 0.5 mm subgingival at the interproximal, and equigingival at the palatal to aid in cement removal. A zirconia coping was fabricated for the implant prosthesis (Procera) and layered to full contour with the appropriate feldspathic porcelain (VITA VM 9). The upper right lateral incisor prosthesis was fabricated using a refractory die insert on the Geller cast with the same feldspathic porcelain as for the implant restoration, thus minimizing the difficulties in shade matching across 2 different substrates (Figure 5).

It was determined on the cast that approximately 0.5 mm more space was needed at the incisal-facial of the right lateral incisor. A reduction coping was fabricated to aid in duplicating the necessary reduction on the tooth. The initial try-in of the restorations revealed that they were approximately half a shade too low in value (evaluated using the monochromatic image [Figure 6a]) and the hue was too blue (evaluated using the full color image [Figure 6b]). The restorations were remade, making the appropriate adjustments to value and hue.

The subgingival portion of the zirconia abutment was coated with petroleum jelly to prevent cement retention, and then torqued to place using the zirconia specific screw to 35 Ncm (Figure 7). The screw access was cleaned with alcohol-free 2% chlorhexidine (CAVITY CLEANSER [BISCO Dental Products]) and obturated using a clear vinyl polysiloxane material (TESCERA Clear PVS [BISCO Dental Products]). Next, the implant prosthesis was cemented using GI cement (Fuji 1 [GC America]), then meticulously cleaned. The GI cement provides adequate retention for implant crowns and is partially soluble in the oral environment to minimize the chance of peri-implantitis, should any cement be inadvertently retained subgingivally. The prosthesis for the upper right lateral incisor was etched, silanated, and bonded in place with a light-cured resin cement to minimize post-cementation color shift (BIS-SILANE; ALL-BOND 3; CHOICE 2 [BISCO Dental Products]).

DISCUSSION
Evaluation at 18 months post-cementation (Figure 8) showed an improvement of the height of the papilla adjacent to the implant (Figure 9), with complete reattachment of the mid-facial gingiva on the upper right lateral incisor (Figure 10). The heights of the interproximal papilla adjacent to the implant would have likely been retained in a more coronal position had a provisional restoration been placed at the time of the surgery. Though the patient had a thin gingival biotype, the gingival color above the implant showed no signs of discoloration; this was due to the use of the zirconia abutment, and an all-ceramic prosthesis with proper placement of the implant toward the palatal (Figure 11).

IN SUMMARY
This case report demonstrates the interdisciplinary treatment of a fractured tooth in the aesthetic zone with an immediate implant, and the treatment of the contralateral tooth with an all-ceramic prosthesis. Collaboration among the surgeon, restorative dentist, endodontist, and the dental laboratory technician (ceramist) created an environment in which multiple challenges (thin and highly-scalloped gingival biotype, and complex tooth characterization) could be successfully managed.

References

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Dr. Schoenbaum is an assistant clinical professor at the University of California, Los Angeles (UCLA) Division of Restorative Dentistry and is director of the UCLA Continuing Education Department. He is a Fellow in the AGD and the American College of Dentists. He also maintains a private practice within the UCLA faculty group dental practice with an emphasis on aesthetics and implant prosthetics. He has lectured internationally and published numerous papers on implants and aesthetics. He can be reached at (310) 267-3380 or at tschoenbaum@dentistry.ucla.edu.

Dr. Klokkevold received his DDS from UCLA and his MS in oral biology from UCLA. He is an associate professor of periodontics at the UCLA School of Dentistry. He can be reached via e-mail at the address pklokkevold@dentistry.ucla.edu.

Mr. Chang received his BS in dental technology from Louisiana State University and his master dental ceramist from UCLA. He is a dental technician with the Burbank Dental Laboratory and the University of Southern California. He can be reached via e-mail at chang@chang-lu.com.

Dr. Kang received his DDS and PhD from UCLA. A professor in the section of endodontics at UCLA, he can be reached via e-mail at mkang@dentistry.ucla.edu.

The authors report no disclosures.