Anteriors

Considerations for Anterior Implant Esthetics

Gregory J. Conte, DMD, MS; Paul Rhodes, DDS, MS; David Richards, DDS, PhD; and Richard T. Kao, DDS, PhD

Copyright 2002 Journal of the California Dental Association.

About the Authors:

Gregory J. Conte, DMD, MS, is an assistant clinical professor in the Division of Periodontology at the University of California at San Francisco and maintains a private practice in San Francisco.

Paul Rhodes, DDS, MS, maintains a private practice in Walnut Creek, Calif.

David Richards, DDS, PhD, maintains a private practice in San Diego, Calif.

Richard T. Kao, DDS, PhD, is an associate adjunct professor in the Department of Periodontology at the University of the Pacific and maintains a private practice in Cupertino, Calif.

There are several factors to consider when restoring failing dentition in the anterior region. While a tooth can be replaced with an implant, achieving an esthetic result is challenging. The dental team must evaluate numerous criteria to define the optimal treatment plan. Among the considerations are whether to extract the tooth and perform immediate implant replacement or to perform a ridge preservation procedure. This article presents diagnostic determinants to help decide the most appropriate course of therapy to achieve functional and esthetic results.

The esthetic replacement of maxillary anterior teeth with an implant-supported prosthesis is now possible. The delivery of esthetic and natural-appearing crowns and/or bridges supported by implants requires careful and detailed treatment planning. This paper will describe steps that maximize the opportunity for delivering an esthetic implant-supported prosthesis.

Far too often, it is the natural inclination of the restorative dentist to expedite treatment by extracting failing teeth. Following extraction, a stayplate or a provisional bridge would be provided. Unfortunately, this may be a critical mistake. Without treatment planning that takes into account how the tissue will respond, the remodeling process will often compromise the final esthetics. The papilla will be lost, and the alveolar ridge may remodel, thereby causing deficiencies in the apical and lingual direction.

The first decision to make is whether the failing tooth is needed for implant site development. The failing tooth may be useful in situations where significant bone loss is associated with the failing tooth but not with adjacent teeth. If one extracts the tooth, the bone level may be more apical relative to the adjacent teeth. This creates a difficult situation for impression taking and implant-supportive maintenance. As plaque accumulates at the implant interface, the inflammation may adversely affect the periodontal status of adjacent teeth. The ideal treatment is to delay the extraction so the failing tooth can be orthodontically extruded.¹ As this is done over the course of six months, the bone and periodontal attachment surrounding the failing tooth will be coronally positioned to match adjacent bone levels. This provides more ideal bone height and allows the restorative implant platform to be placed at the desired height of 3 to 4 mm subgingivally. This paper will focus on situations where the failing tooth needs to be extracted and define key determinants for preserving hard and soft tissue for an optimal implant-supported prosthesis.

The ideal time to surgically place an implant is at the time of extraction. The implant will support and maintain the existing alveolar bone and soft tissue.^2-4 Immediately placed implants can be provisionalized at the time of implant placement or during the implant uncovering procedure.

Immediate implant placement with immediate provisionalization is ideal for preserving tissue integrity and satisfying patient demand for an esthetic provisional during osseointegration. In this situation, the abutment is attached to the newly placed implant and an acrylic crown is temporarily cemented. This provisional will support the soft tissue, including the surrounding papillae. It is important to ensure that the provisional is nonfunctional so that the implant is not prematurely loaded. Premature occlusal loading may interfere with osseointegration. This treatment provides the patient with the most esthetic provisional possible. It is crucial to emphasize the importance of not loading the area during mastication.

Alternatively, the implant surgical area can be provisionalized with a stayplate or bridge. If a stayplate is used, the pontic should be an ovate form and extend into the socket to support the soft tissue. Unfortunately, the movement of a stayplate can adversely infringe on the papilla. If possible, a better alternative is to use a fixed provisional bridge with an ovate pontic that extends into the socket. This extension will support the adjacent papilla and minimize soft-tissue loss. However, despite the best effort to support the soft tissue with a stayplate or provisional bridge, marginal tissue remodeling and papilla loss will generally occur. This can compromise the final esthetics. This approach, though effective, does not usually provide the optimal esthetic outcome that is possible with immediate implant placement and provisionalization.

The last post-extraction situation is when an immediately placed implant is not an option due to significant loss of the labial plate. This loss can be due to surgical trauma, extensive dehiscence/fenestration, multiple episodes of parulis formation, and a weakened labial plate resulting from previous endodontic surgery. Since healing is unpredictable, this makes immediate implant placement a risky proposition. The treatment of choice in this situation is to perform a ridge preservation/augmentation procedure. In this situation, the goal is to preserve or regenerate the alveolar ridge so an implant can be placed later. Interdental papilla are usually lost, and the appropriate gingival crest level is often more apical that the contralateral tooth. These soft-tissue defects are often difficult, if not impossible, to correct surgically. Additionally, this approach is disheartening for the patient because it will delay treatment by three to six months.

Numerous options must be considered to achieve optimal esthetics with implant-supported prosthesis. It is important for the restorative dentist to realize that the best chance for maximizing the esthetics is to work as a member of an interdisciplinary team in analyzing which option is ideal. The restorative dentist needs to learn how to triage these patients and appreciate how the clinical information may favor one option over another. This paper will define diagnostic determinants and treatment-planning considerations for the esthetic restoration with an implant-supported prosthesis.

Diagnostic Evaluation for Predictable Functional and Esthetic Results

There are several factors to consider when planning an implant restoration of failed dentition in the esthetic zone. Most often, the esthetic zone involves the maxillary anterior dentition. Although the single-tooth implant-supported restoration appears simple to perform, it is the most challenging in the esthetic zone. One of the initial assessments is determining if the tooth in question is a candidate for immediate implant replacement or a ridge preservation procedure. This assessment will define the type of provisional that will be needed.

There are advantages to immediate dental implant placement. Research suggests that immediate implantation may preserve the alveolar bone, and placement of a fixture into a fresh extraction socket may help maintain the alveolar crest.^2-4 This can lead to an optimal esthetic outcome if specific diagnostic criteria are met. Immediate implantation may allow for immediate or early provisionalization, which can be used to help contour and shape the soft tissue at the restorative gingival interface (Figures 1a through i). In addition, treatment time can be reduced by three to six months if an implant can be placed at the time of extraction.

Diagnostic Evaluation for Immediate Implantation in the Esthetic Zone

Radiographic Assessment

The diagnostic evaluation begins with a radiographic assessment of the failing tooth. Ideally, the tooth should be free of periapical and inter-radicular pathology. Should pathology be present, some believe that an immediate implant placement can be performed with the provision that all pathological tissue and adjacent bone are removed during the site preparation. When there are doubts or questions about whether infected tissue remains, the risk for non-osseointegration, loss through infection, or partial integration with delayed implant failure would make tooth extraction and ridge preservation a more prudent choice. The interproximal bone height should be at a normal level, approximately 1 to 2 mm apical to the cemento-enamel junction of the adjacent teeth.⁵ There must be sufficient bone beyond the apex of the failing tooth root to achieve primary implant stability (Figure 1c). If any of the above radiographic criteria are not met, the tooth should be extracted, and a bone graft and possibly a soft-tissue graft should be performed. The area should be allowed to heal for three to six months. The healing period depends upon the extent of the labial defect and the rate of healing. Extensive loss generally will require four to six months of healing prior to implant placement.

Soft-Tissue Assessment

Soft-tissue assessment is most important in the diagnostic evaluation for implant restoration in the esthetic zone. The existing gingival position of the failing tooth must first be evaluated. Approximately 1 to 2 mm of facial gingival recession may result following tooth removal and immediate implant placement.⁶ Therefore, a hopeless tooth with a free gingival margin 1 to 2 mm more coronal to its contralateral counterpart is more favorable (Figure 2a). Conversely, a hopeless tooth with free gingival margin positioned at the same level or more apical than its contralateral counterpart is not favorable because of the ensuing apical resorption that occurs with wound healing (Figure 2b). This is especially true if the patient has a high smile line. Under these conditions, orthodontic extrusion of the failing tooth prior to extraction is recommended.⁷ The extrusion of the tooth will result in the development of both soft and hard tissue in a more coronal position. This allows the implant platform to be positioned where it can be managed prosthetically and during post-treatment supportive maintenance care. This method of tissue regeneration can compensate for the hard- and soft-tissue deficiencies to create a harmonious soft-tissue level as well as additional bone.

Next in the soft-tissue assessment is to evaluate the gingival scallop and gingival biotype. Gingival scallop has been categorized as flat, scalloped, and pronounced scallop, and is defined by the distance between the mid-facial and interproximal tissue height.⁸ The biotype of the gingiva is typically considered as thick or thin. Based on clinical data, the average or normal gingival scallop is 4 to 5 mm.⁹ Teeth with a normal or pronounced gingival scallop and a thin biotype are more prone to gingival tissue recession and interproximal tissue loss following tooth extraction. This is less likely to occur on teeth with a flat gingival scallop and a thick biotype⁹ (Figures 2a and b). Highly scalloped cases with a thin gingival biotype require special attention to ensure predictable peri-implant esthetics. In these cases, flapless surgical extraction and implant placement are advantageous because they minimize bone loss, which decreases gingival recession.¹¹ This procedure, however, is quite challenging due to lack of visibility and the thin labial plate of bone. It requires careful planning and flawless surgical execution. It may be optimal to extract the hopeless tooth, perform hard- and soft-tissue grafting, and place the implant three to six months later.

The final parameter in the soft-tissue assessment is the height of the interdental papilla. Interdental papilla height is determined by the position of the underlying osseous crest and the height of the interproximal contact area. In the normal dentogingival complex, interproximal papilla height is approximately 4.5 mm from the osseous crest.^12-13 The greater this distance, the greater the risk of tissue loss following extraction and immediate implant placement. This tissue is often difficult to re-establish, especially for the thin/scalloped periodontium. Therefore, maintenance of the interdental papilla is critical at the time of tooth removal by immediate tooth replacement using a fixed or removable prosthesis. The provisional restoration must support approximately 3 mm of unsupported soft tissue with gentle pressure that exerts laterally to support the full height of the interdental papilla.

The height of the contact area with the adjacent teeth is also important in interdental soft-tissue height. In a clinical study of the natural dentition, it was determined that the presence or absence of interproximal papilla fill was inversely related to the distance from the base of the contact area to the underlying crest of bone.¹⁴ At a distance of 5 mm or less, the papilla fill was present virtually 100 percent of the time. When the distance measured 6 mm, papilla fill was present 56 percent of the time. At a distance of 7 mm or more, papilla fill was present in only 27 percent of the sites examined.

Hard-Tissue Assessment

Numerous studies have established a relationship between the gingiva and the underlying bone for both the natural dentition and dental implants.^8-12 For immediate implant-supported restorations, the facial free gingival margin is supported by the existing facial bone of the failing tooth, and the interproximal gingival tissue is determined by the interproximal bone level of the adjacent tooth. Bone sounding under anesthesia is used to assess these dimensions and is an important and valuable diagnostic procedure prior to extraction. Normal relationship from the free gingival margin to the underlying osseous crest was found to have a facial dimension of 3 mm and an interproximal dimension of 4.5 mm.^15-16 If the facial gingival levels are harmonious between the hopeless tooth and the adjacent tooth, and the distance to the osseous crest is 3 mm or more, orthodontic extrusion prior to extraction would allow for a more favorable esthetic result. If the interproximal height to the osseous crest is greater than 4.5 mm, soft-tissue loss can be expected following implant placement and restoration. A common misconception is to measure the interproximal bone height of the failing tooth. It is, however, the interproximal osseous position of the retained adjacent teeth that will provide the foundation for interproximal tissue in the final restoration. If this distance is greater than 4.5 mm, the patient needs to be aware that prosthetic compromise may be needed to close the interproximal space.

The shape and position of the hopeless tooth also need to be evaluated in the diagnostic assessment for immediate implant placement. Square-shaped teeth may have a more favorable esthetic outcome than ovoid or triangular-shaped teeth because the interproximal contact is longer and more tooth structure fills the interdental space (Figures 3a and b).¹⁵ There is less risk of interproximal recession with this shape tooth than there is with a tooth with a triangular/taper shape, where the interproximal contact area is positioned incisally and more tissue height is needed to fill the interproximal area. Even the slightest amount of tissue loss may create interproximal black triangles.

Labial alveolar bone and the overlying soft tissue is often thin when teeth are positioned too far facially. Extraction and immediate implant placement may result in perforation, or extensive loss of the labial bone and the collapse of the gingival architecture. In this case, ridge augmentation and preservation procedures prior to implant placement may result in a more favorable esthetic outcome (Figures 4a through f). On the other hand, lingual tooth position often results in thicker labial bone and gingival tissue. A hopeless tooth in this position is more favorable for immediate implant placement due to less likelihood of damage during extraction and implant placement. In addition, soft-tissue loss may be minimized, and there would be less chance of a gingival discrepancy in the final restoration.

Conclusion

Accurate diagnosis and treatment planning are essential in achieving optimal implant esthetics. Immediate implant placement following extraction of a hopeless tooth can often result in ideal functional and esthetic results if specific diagnostic criteria are evaluated and the appropriate treatment rendered. Too often, results are compromised because of failure to accurately assess the multiple factors involved with extraction and immediate implant placement in the esthetic zone. The restorative team must have a thorough understanding of the osseous and soft-tissue profiles associated with a failing tooth to decide if immediate implant placement will achieve the desired esthetic result. In situations where immediate implant placement is not possible, ridge preservation needs to be performed to minimize tissue loss. This will minimize the corrective augmentation procedures necessary to obtain an esthetic result with delayed implant placement. Delayed placement, unfortunately, requires more surgical effort, time, and expense to achieve an acceptable esthetic result. Whenever possible, the restorative dentist should consider collaborating with the surgeon in evaluating if an immediate implant can be placed. This would provide the optimal esthetic end result.

References

1. Spear FM, Mathews DM, Kokich VG, Interdisciplinary management of single-tooth implants. Semin Orthod 3:45-72, 1997.

2. Dennisen HW, Kalk W, et al, Anatomic consideration for preventive implantation. Int J Oral Maxillofac Implants 8:191-6, 1993.

3. Shanaman R, The use of guided tissue regeneration to facilitate ideal prosthetic placement of implants. Int J Periodontics Restorative Dent 12:257-65, 1992.

4. Watzek G, Haider R, et al, Immediate and delayed implantation for complete restoration of the jaw following extraction of all residual teeth: A retrospective study comparing different types of serial immediate implantation. Int J Oral Maxillofac Implants 10:561-7, 1995.

5. Reed BE, Polson AM, Relationships between bitewing and periapical radiographs in assessing crestal alveolar bone levels. J Periodontol 55:22-7, 1984.

6. Kois JC, Esthetic extraction site development: The biologic variables. Contemp Esthetics Restorative Practice 2:10-8, 1998.

7. Salama H, Salama M, The role of orthodontic extrusive remodeling in the enhancement of soft and hard tissue profiles prior to implant placement: A systematic approach to the management of extraction site defects. Int J Periodontics Restorative Dent 13:312-33, 1993.

8. Becker W, Ochsenbein C, et al. Alveolar bone anatomic profiles as measured from dry skulls. Clinical ramifications. J Clin Periodontol 24:727-31, 1997.

9. Kois JC, Altering gingival levels: The restorative connection. Part I: Biologic variables. J Esthetic Dent 6:3-9, 1994.

10. Olsson M, Lindhe J, Periodontal characteristics in individuals with varying forms of the upper central incisors. J Clin Periodontol 18:78-82, 1991.

11. Garber DA, Salama MA, Salama H, Immediate total tooth replacement. Compend Contin Educ Dent 22:210-8, 2001.

12. Salama H, Salama MA, et al, Developing optimal peri-implant papillae within the esthetic zone. Guided soft tissue augmentation. J Esthetic Dent 7:125-9, 1995.

13. Saadoun A, LeGall M, Touti B, Selection and ideal tridimensional implant position for soft tissue aesthetics. Pract Periodont Aesthet Dent 11:1063-72, 1999.

14. Tarnow DP, Magner AW, Fletcher P, The effect of distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol 63: 995-6, 1992.

15. Kois JC, Predictable single tooth peri-implant esthetics. Five diagnostic keys. Compend Contin Educ Dent 22:199-208, 2001.

16. Kan JYK, Rungcharassaeng K, Site development for anterior implant esthetics: The edentulous site. Compend Contin Educ Dent 22:221-32, 2001.

To request a printed copy of this article, please contact/Gregory J. Conte, DMD, MS, 345 W. Portal Ave., San Francisco, CA 94127 or gregconte@aol.com.

Legends

Figure 1a. Preoperative facial view demonstrates erythema along the labial free gingival margin of the maxillary left lateral incisor.

Figure 1b. Close-up view of the lateral incisor shows the red, boggy tissue. Note the thin scalloped periodontium.

Figure 1c. Periapical radiograph reveals a root resorptive defect on the distal of the tooth. There has also been apical root resorption. This provides a large quantity of bone apical to the existing root.

Figure 1d. Atraumatic extraction of the tooth. A periotome was used between the periodontal ligament space and the alveolar socket to sufficiently loosen the root. The tooth was removed without damage to the thin labial plate.

Figure 1e. Surgical stent used in preparation for implant placement. The stent was fabricated on a diagnostic cast based on radiographic analysis of the alveolar bone height and width.

Figure 1f. Implant placed in the proper buccal-lingual, mesial-distal, and apico-

coronal position.

Figure 1g. Periapical radiograph of the implant with a custom temporary abutment used for the provisional restoration.

Figure 1h. The screw-retained provisional restoration is placed immediately upon implant placement. The soft tissue is closed around the provisional to allow for proper soft-tissue development.

Figure 1i. Six-month view of provisional restoration. The interproximal papilla have been maintained, however, there has been a slight change in the position of the labial free gingival margin.

Figures 2a and b. The maxillary right central incisors in Figures 2a and 2b have poor prognosis due to root resorption. The tooth in Figure 2a is in a more favorable position for extraction and immediate implant placement because the free gingival margin is coronal to the contralateral tooth. In addition, the thick gingival biotype is preferred over the thin, scalloped gingiva seen in Figure 2b. Orthodontic extrusion prior to extraction and implant placement is recommended for the right central incisor in 2b.

Figures 3a and b. Examples of different tooth shapes. The maxillary central incisors in 3a are long and triangular with the contact area located incisally. The central incisors in 3b are square shaped with a long interproximal contact. This is more favorable for extraction and immediate implant placement.

Figure 4a. Tooth #6 has a hopeless prognosis.

Figures 4b and c. On extraction, there is a perforation of the labial plate.

Figure 4d. The extraction site was augmented for ridge preservation, and graft material with a Gore-Tex augmentation material membrane was used to expand the osseous volume of bone.

Figures 4e and f. Six months later, the ridge has been augmented with good radiographic bone density.