Nonconventional Rehabilitation for Anterior Single Tooth Loss: Clinical Follow-Up at 12 Years

INTRODUCTION
When a maxillary anterior tooth is extracted, a major concern is its immediate aesthetic replacement, which is particularly challenging when the adjacent teeth are caries-free and have good aesthetics.^1-5 The replacement of single teeth by dental implants is one prosthodontic approach that allows for greater preservation of adjacent teeth and solves the aesthetic problems of alternative procedures, such as resin-retained fixed prostheses.²

Immediate implant placement has several advantages, such as reduction of the number of surgical treatments, reduction of the time between tooth extraction and placement of the definitive prosthetic restoration, prevention of bone resorption, and preservation of the alveolar ridge in terms of height and width, which in turn has aesthetic and functional benefits.^3,6-13

In the anterior zone, the success of single-implant therapy is determined not only by high survival rates, but also by the long-term quality of survival, dictated by a combination of several factors. Restorations should satisfy the patient’s expected aesthetic and functional objectives. Aesthetics and function are of equal concern in the restoration of dentition in the anterior area, or “aesthetic zone.” It is challenging to restore a maxillary central incisor and essential for the new restoration to blend with the adjacent teeth.^{1,3-6,10,12,13}

Depending on the conservation of a portion of the crown, the possibility of using the crown itself for definitive rehabilitation has been proposed, to maintain aesthetics and establish tooth wear patterns similar to those of adjacent teeth, especially in young patients. Thus, this paper describes an implant-based prosthetic therapy concept for application of a natural tooth’s crown in the rehabilitation of a trauma-induced missing anterior tooth, with a 12-year follow-up.

CASE REPORT
Diagnosis and Treatment Plan
A 19-year-old male lost tooth No. 11 as a result of trauma to the anterior region of the upper jaw (Figures 1a to 1c). In the same surgical procedure, the tooth was extracted and an immediate self-tap implant (18 x 3.75 mm [BIOMET 3i]) was placed without an incision. After implant placement, a healing abutment was used for one-stage surgery that allowed for maintenance of the central incisor emergence profile (Figures 2a and 2b). Adhesive temporary restoration with fiberglass ribbon (Connect [Kerr]) and denture teeth (Biotone [DENTSPLY Prosthetics]) was performed. The natural tooth lost due to trauma was stored in saline solution, changed weekly, for use in the final restoration, to provide ideal aesthetics and proportional tooth size and wear.

Clinical Protocol
After a 6-month osseointegration period, the provisional crown and healing abutment were removed. Using an implant analog attached to the healing abutment, a silicone impression (Zetaplus [Zhermack]) was taken. A 4.1-mm temporary abutment (BIOMET 3i) was then attached in the analog inside the impression, and acrylic resin (Pattern Resin LS [GC America]) was inserted into the silicone mold, allowing for the creation of the same healing abutment profile as in the implant-retained temporary crown.

A square transfer (BIOMET 3i) was adapted to the same silicone mold as used in the previous step, and acrylic resin (Pattern Resin LS) was again inserted to transfer customization. After this customization, the transfer was installed in the implant, and an individual tray was filled with a polyether (Impregum Soft [3M ESPE]) to obtain the impression, after which the master was cast in a Type IV plaster. From the master cast, an AurAdapt abutment (Nobel Biocare) was selected, and the waxing and casting were then carried out using a palladium-silver alloy. Next, feldspathic ceramic was applied to the metal framework, completely covering the metal. Concomitantly, the clinical crown of the natural tooth was deemed adequate through wear of the root portion and an internal emptying procedure (only part of the dentin). Then, the internal part of the crown was relined with light-cured composite resin, to improve fit (Z100 [3M ESPE]).

The porcelain on the abutment was etched with 10% hydrofluoric acid for 60 seconds, then rinsed and dried for posterior application of a silane (Silane Coupling Agent [DENTSPLY Caulk]). After this step, the abutment was attached to the implant, radiographed, and mechanically tightened to a torque of 32 Ncm. The internal crown surface was etched with 37% phosphoric acid, a 3-step etch-and-rinse adhesive was applied (Scotchbond Multi-Purpose Plus [3M ESPE]), and cementation was carried out using a dual-cure resin cement (RelyX ARC [3M ESPE]) (Figures 3a to 3c).

Figure 4a demonstrates the appearance provided by rehabilitation, as well as the fit of the abutment and crown in the radiograph of Figure 4b. At 12 years postoperatively, new clinical and radiographic evaluations of the rehabilitation were conducted for analysis of function, aesthetics, and patient satisfaction (Figures 5a and 5b).

DISCUSSION
The placement of an implant immediately after tooth extraction may help maintain the bone crest and lead to ideal implant positioning from a prosthetic point of view.^1,8 It is well known that after tooth extraction, the residual alveolar ridge generally provides limited bone volume because of progressive bone resorption. Healing events within post-extraction sockets reduce the dimensions of the socket throughout time.^{1,3,8,9,11,12,14} The placement of implants shortly or immediately after tooth extraction has proven to be a predictable treatment strategy with a very high rate of success, allowing for placement of the implant during the same visit at which the tooth is extracted; this clinical technique reduces morbidity, decreases treatment time, and preserves bone in the residual alveolar ridge.^3,9-11,15,16

Twelve years ago, one-stage surgical procedures for implants at the time of placement showed promising clinical results. However, the immediate loading of single implants in the maxilla hads not been extensively investigated,⁵ and since the procedures for this technique were recently consolidated, an undisturbed healing period is required to ensure osseointegration.¹⁰

The management of soft tissue is arguably even more challenging when an implant in the aesthetic zone is restored. Coordinated treatment by the restorative dentist and the dental laboratory team is critical to achieving a successful outcome.^7,9,10 In our case, the use of a healing abutment was essential for maintenance of the central incisor emergence profile.

Custom transfer, sculpting, and capture of the peri-implant tissues in the resting position will eventually allow for the development of the correct emergence profile of the restoration, and do not require additional components or laboratory steps other than those used routinely to make impressions of implant positions.¹³

The preservation or regeneration of interproximal papillae is critical to the aesthetic success of single implant-supported crowns. Various factors may contribute to the anatomical form of papillae adjacent to single-implant crowns, including alveolar crest height at adjacent teeth and maintenance of biologic width.^8,9 Implants and abutments with specific configurations have been introduced to sustain the hard and soft tissues,12 together with provisional techniques to restore the soft-tissue contour,^6,7 as well as the introduction of customized ceramic abutments and ceramic implant crowns.^12,17 It is preferred that the appearance of the peri-implant soft tissue be in harmony with the mucosa around the adjacent teeth. In addition, the neighboring dentition and the implant crown should be in aesthetic harmony.^4,6,8 Various implant treatment strategies have been proposed for the accomplishment of optimal aesthetics.^4,17

The ceramic abutment was selected due to the inclination of the implant in the incisal direction, which prevented the installation of a screw-retained prosthesis. Among the cemented options, metal abutments were eliminated due to the possibility of compromising the gingival aesthetics by the presence of a thin keratinized mucosa. The all-ceramic abutment seemed to be the only option, but carried with it the difficulty of adapting to the emergence of natural gums and the remaining crown. For this reason, it was decided to customize the emergence of the pillar by the application of feldspathic ceramic to metal, turning it into a metal completely covered by a ceramic abutment; conformation was determined by adjustment with the remaining natural tooth. The firing of ceramic creates contraction, and to minimize this effect in the settlement of the crown, it was relined with composite resin. Among the existing ceramic pillars, another possibility for solving this case would be to use abutments produced by CAD/CAM processing, and while CAD/CAM technology has become much more affordable and has been proven successful longitudinally, the dearth of longitudinal studies and the high cost led us to choose the first alternative.

The metal-ceramic abutment represents an alternative that provides predictable biomechanics confirmed in the anterior region, with vertical fitting and horizontal and rotational freedom similar to those of metal abutments.4 Their use allowed us to take advantage of abutment screws that support the application of higher torques, transferring greater preload, increasing the stability of the implant/abutment interface, and minimizing the possibility of screw-loosening, which is not uncommon in this kind of rehabilitation and could lead to serious aesthetic problems when the screws are retightened.¹⁸

Complex technical procedures are undoubtedly one disadvantage of this technique that must be considered when treatment is selected. While the possibility of caries development throughout the years still existed, the ceramic facilitated satisfactory maintenance of aesthetics, the same amount of wear, and harmony with adjacent teeth, due to tooth brushing and proximal wear.

The use of extracted teeth offers, as an additional advantage, a favorable psychological factor, since it provides an excellent alternative for preserving the shape, color, and harmony of the patient’s natural teeth and smile.¹ At 12 years postoperatively, the treatment was shown to be efficient, preserving function while lacking the problems related to hard and soft tissues. A small chip in the cervical region of the crown was found, but there were no major problems related to the natural aesthetics and patient satisfaction. Porcelain repair using a composite resin was suggested, but the patient chose periodic monitoring every 4 months for observation and hygiene control, without any additional intervention.

CLOSING COMMENTS
This case report presented an unusual but, in the authors’ opinions, feasible method of rehabilitation. This is an excellent treatment option for young individuals who have suffered the loss of anterior teeth and whose crowns remain in good clinical condition. Besides the aesthetic benefits, the similarity of dental attrition over the years—which cannot be achieved with some of the available all-ceramic restorations—should be considered. At 12 years, the treatment was shown to be successful in preserving function, and there was an absence of problems related to the soft and hard tissues. Although minor cosmetic changes were observed throughout time, they have not affected overall patient satisfaction. Follow-up with a larger number of cases during a similar period would be important to validate the findings in this case.

References

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Dr. Neves is in private practice in Uberlândia, Brazil, and is an associate professor at Uberlândia Dental School, Federal University Uberlândia, Brazil. He can be reached via e-mail at neves@triang.com.br.

Disclosure: Dr. Neves reports no disclosures.

Dr. Silva is a PhD student at Piracicaba Dental School, State University of Campinas, Brazil. He can be reached via e-mail at joaodf22@hotmail.com.

Disclosure: Dr. Silva reports no disclosures.

Dr. Silva-Neto is in private practice in Natal, Brazil, and is a PhD at Piracicaba Dental School, State University of Campinas, Brazil. He can be reached via e-mail at the address joaopaulosneto@gmail.com.

Disclosure: Dr. Silva-Neto reports no disclosures.

Dr. Castro is a PhD student at Uberlândia Dental School, Federal University Uberlândia, Brazil. She can be reached via e-mail at the address morgana_castro3@hotmail.com.

Disclosure: Dr. Castro reports no disclosures.

Dr. Fernandes-Neto is a titular professor at Uberlândia Dental School, Federal University Uberlândia, Brazil. He can be reached via e-mail at alfredon@ufu.br.

Disclosure: Dr. Fernandes-Neto reports no disclosures.

Dr. Simamoto-Júnior is an adjunct professor at Uberlândia Dental School, Federal University Uberlândia, Brazil. He can be reached at psimamoto@foufu.ufu.br.

Disclosure: Dr. Simamoto-Júnior reports no disclosures.