Soft- and Hard-Tissue Augmentation by Orthodontic Treatment in the Esthetic Zone

One method of compensating for alveolar ridge deficiency is using block bone grafts. These grafts are predominantly cortical, exhibit little resorption, and tend to incorporate extraordinarily well with recipient bone within a relatively short timeframe. They also maintain bone volume post-implant and retain a density similar to the enhanced site.³ Despite the many advantages block grafts offer for alveolar ridge augmentation, there are complications when used for horizontal and vertical augmentation.

Morbidity is associated with both donor and recipient sites. Donor site morbidity of the symphysis may involve complications such as bleeding, mental nerve injury, and soft-tissue injury of areas like the cheeks, lips, and tongue, as well as block graft fracture.³ Pain, swelling, bruising, and neurosensory deficits that include altered sensation of the lower lip and chin can occur. The ramus buccal shelf harvest may cause complications that include bleeding, soft-tissue injury, nerve-tissue injury, block fracture, and mandible fracture.³

Postoperative morbidity includes trismus, pain, swelling, bruising, and altered sensation of the lower lip/chin and lingual nerve. Trismus, swelling, bleeding, pain, bruising, infection, bone resorption, neurosensory deficits, dehiscence, and graft failure may show up in recipient sites.³

“Orthodontic tooth extrusion” is a term used to describe the forced movement of teeth in the vertical plane with moderate forces. It has been suggested that extrusion of single teeth may be employed as an adjunctive measure in periodontal therapy aimed at eliminating or reducing angular bone defects, without compromising the periodontal attachment apparatus of neighboring teeth.^4-9 The effect of orthodontic extrusion on the periodontal tissues has been assessed in both clinical studies and animal experiments. Early studies by investigators including Oppenheim,¹⁰ Ritchey and Orban,¹¹ and Reitan,¹² documented that: 1) extrusion resulted in bone apposition at the apex as well as at the alveolar crest of the relocated tooth; and 2) the alveolar crest of a healthy periodontium would maintain a normal (1 mm to 2 mm) relationship with the cementoenamel junction. Batenhorst et al¹³ reported that extrusive tooth movement in the monkey not only resulted in apposition of crestal bone, but also generated an increase in the width of the attached gingiva. Van Venrooy and Yukna¹⁴ used a dog model to assess the effect of orthodontic extrusion of teeth associated with advanced periodontal disease. The authors extruded teeth a distance of 3 mm to 4 mm and observed that at the test teeth compared to non-extruded controls, the inflammation of the gingival tissue was less pronounced, and the periodontal pockets were less deep. They also found that extrusion resulted in apposition of the crestal bone. It was suggested that extrusion of teeth with advanced periodontal disease: 1) may move a subgingival microbiota into a supragingival position; and thus 2) may have a therapeutic effect on periodontitis. Pontoriero et al¹⁵ and Kozlowsky et al¹⁶ devised a technique for tooth extrusion that combined orthodontic force application with resection of the supracrestal attachment fibers (fiberotomy). The combined procedure was performed in a series of clinical cases and was found to promote the extrusion of single teeth but to prevent the concomitant coronal migration of the periodontium. A predetermined portion of the tooth then became exposed and accessible for restorative procedures. Thus, forced eruption is a viable method to alter the gingival margins. The most universal set of clinical indications for the use of forced eruption is in those cases where it is undesirable to remove gingival tissue from the adjacent teeth and where an additive surgical procedure would not be predictable (ie, covering a root surface). In addition to the above, an ideal indication for forced eruption would be the instance of artificial crowns, where recession is present as a result of trauma during or after their placement.

A 62-year-old woman presented to the department of Advanced Prosthodontics at the University of Southern California. Her chief complaint was increasing mobility and spacing among her maxillary anterior teeth. Her medical history was noncontributory. An intraoral examination revealed Grade II and III mobility on her maxillary anterior teeth, together with fremitus (Figure 1).

There was no trismus, or limitation of mouth opening. A perusal of her radiographs demonstrated severe bone loss around maxillary anterior teeth, with up to 80% attachment loss on the lateral incisors (Figure 2).

After data collection and diagnosis, a comprehensive treatment plan was developed for the patient. One of the diagnoses was loss of posterior support. The authors believed that this directed undue force to the maxillary anterior teeth, subjecting them to occlusal trauma that contributed to attachment loss, mobility, and fremitus. With restoration of the posterior support, reduced mobility and possible elimination of fremitus was expected for teeth Nos. 8 and 9, and possible improvement in periodontal attachment levels.

It was the patient’s desire to avoid using a removable prosthesis during the treatment. The first phase of the treatment plan was root planing of maxillary anterior teeth (Figure 3 through Figure 5), followed by the orthodontic extrusion of teeth Nos. 7 and 10. Three months after extrusion, tooth No. 10 became sensitive due to the necessity for incisal reduction as the tooth was erupted and required a pulpotomy. Seven months after extrusion, the volume of available bone and soft tissue was examined clinically and radiographically. The volume of hard and soft tissue was considered adequate to enable placement of an implant with an acceptable result (Figure 6 and Figure 7).

The maxillary lateral teeth were extracted as atraumatically as possible and implants were placed immediately. The clinical crowns of the extracted teeth were reattached to the orthodontic apparatus as provisional restorations (Figure 8). Five months later the implants were uncovered, impressions were made, and screw-retained provisional restorations were delivered (Figure 9).

Simultaneously, implant-supported provisional restorations were placed on implants restoring the posterior teeth, thus restoring posterior support. After removal of the orthodontic appliances, the mobility of the central incisors was found to be reduced to less than 1.

After allowing soft tissues to heal and form to the contours of the provisional restorations for 4 weeks, custom-impression copings were used during impression-making in order to duplicate the soft-tissue contours on the master cast. This enabled the laboratory technician to fabricate submucosal contours for the definitive restorations that were identical to those of the provisional restorations (Figure 10).

Definitive restorations were delivered after 2 months. Though teeth Nos. 8 and 9 had some attachment loss their mobility was reduced and it was determined that with proper maintenance they had a good prognosis. An examination of Figure 11 through Figure 13 demonstrates both clinically and radiographically that acceptable esthetics were obtained and implants were well integrated. A comparison of Figure 14 and Figure 15 shows the improvements that were made after treatment was completed.

Osseointegrated implants have allowed patients to have missing teeth replaced in the most conservative way, sparing preparation of adjacent teeth while having a well-documented record of success. However, other challenges present because soft-tissue esthetics around dental implants depend largely on the volume of hard and soft tissue. These challenges have mandated a need for new criteria to guide the planning of the periodontally compromised patient. One criterion at the forefront must be the preparation of a dimensionally adequate recipient site for the implant, so that peri-implant esthetics will be adequate. Additional treatment planning aspects to consider are whether any teeth can be maintained from a periodontal-prosthetic point of view, as well as whether any teeth should be extracted. Also to be considered are techniques to augment potential receptor sites when necessary, and the optimal sequence of implant placement and mucogingival surgical modalities.¹⁷ One of the more difficult problems arises when implant placement has to proceed, despite extraction defects of periodontally compromised patients. It is important to first determine how to ideally manage the residual defects that can often be associated with the extraction of periodontally distressed teeth¹⁷ to allow an implant placement that can support a restoration designed to maintain functional and esthetic harmony with adjacent natural teeth.¹⁷

Extraction, followed by immediate implant placement, has been advocated as a more expedient approach to replacing distressed teeth with implants.^18-20

Improving both soft- and hard-tissue architecture through efficient extrusive tooth movement is well documented.^10-12,14 Brown²¹ and Ingber^4,5,22 pointed to molar uprighting and forced eruption as methods of adjusting the osseous and gingival topography. The gingival fiber apparatus does not have elasticity, therefore stretching it during tooth movement releases tension on the alveolar bone. It is widely accepted that this tension stimulates bone deposition at the alveolar crest.^15,23,24 Extrusive tooth movement also enhances the volume of the soft tissue by increasing the zone of attached gingiva.¹³ This increase occurs because, during this type of movement, the gingival margin migrates coronally, while the mucogingival junction remains stable.²⁵

The osseous crest is a critical foundation for gingival levels. The position of this relationship is a crucial way to gauge what gingival levels will be after an intervention²⁶; the greater the distance of the osseous crest to the free gingival margin (FGM), the greater the risk of tissue loss after an invasive procedure. Orthodontic extrusion is recommended if the distance to the osseous crest is 3 mm or more and the facial gingival levels are balanced enough to compensate for subsequent osseous resorption and potentially greater soft-tissue loss caused by moving the osseous crest more coronally.²⁷

The interproximal bone relationship has also been described as having consistent relationships; the dimensions are based on the most coronal portion of the interproximal osseous crest of adjacent teeth and are not related to the interproximal position of the osseous crest of the tooth being removed. Therefore, if the interdental papilla measures > 4 mm (low crest) on the adjacent teeth, there will predictably be some interproximal tissue loss after extraction to the 3 mm to 4 mm of soft-tissue depth.

Orthodontic extrusion of a failing tooth will not improve the height of the interproximal papilla. This height is determined by the periodontal attachment levels to the adjacent teeth. When the extruded tooth is extracted, the facial bone height will be improved compared to the pre-extraction levels, but the interproximal bone heights will remain largely unchanged.²⁷

The limitations of forced eruption must be pointed out; the gain in bone levels and volume occur largely on the facial aspects of teeth Nos. 7 and 10. This is reflected clinically by the improved facial soft-tissue contours of the implant restorations of teeth Nos. 7 and 10. Forced eruption of these two teeth did little to improve the interproximal bone heights, as this is determined by the attachment levels to the adjacent teeth. A review of the radiographs demonstrates this clearly (Figure 6 and Figure 7). Note the bone levels after forced eruption and retention, and the radiographs post-delivery of the restorations. It is clear that there was little or no improvement of the soft-tissue levels interproximally.

The authors analyzed the part of controlled extrusive tooth movement as a way by which the position of the gingival margin and the bone crest may be altered coronally before tooth extraction. Limitations to the technique were also discussed. This approach may create a greater volume of available bone and soft tissue in the vertical plane without surgical intervention, by focusing on isolated deformities in preparation for implant placement.

Ali Makhmalbaf, DDS
Assistant Clinical Profess
Group Practice Director
Ostrow School of Dentistry of University of Southern California
Los Angeles, California

Winston Chee, DDS
Ralph & Jean Bleak Professor of Restorative Dentistry
Director
Implant Dentistry
Co-Director, Advanced Prosthodontics
Ostrow School of Dentistry of University of Southern California
Los Angeles, California

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