Anterior Tooth Replacement in an Adolescent With a High Smile Line

Research has demonstrated that the completion of skeletal growth before the placement of dental implants is essential to achieve a predictable and esthetic long-term result. Craniofacial growth rates differ between men and women, with men typically lagging 1 to 3 years behind women. Theoretically, craniofacial growth continues throughout life, but after an individual is 20 years old, the growth is insignificant.¹ Maxillary growth has been deemed to be multidirectional, and it occurs in three different dimensions: transverse, sagittal, and vertical.^2,3

As the width of the cranial base increases and the median suture grows, it influences the transverse growth of the maxilla. During puberty, this sutural growth accelerates. The transverse dimension is the first of the three dimensions in which growth is completed.⁴ Placing an implant before this occurs can lead to a diastema between the restoration and the adjacent teeth as transverse growth continues. In addition, tooth size to arch length discrepancy increases from early adolescence to mid-adulthood in both the maxillary and mandibular arches.⁵ Therefore, a reduction in arch length and increased crowding during the period of maximum growth can lead to an implant crown that is out of alignment with the adjacent natural teeth.⁶

Sagittal growth of the maxilla occurs anteriorly with natural resorption, causing the maxilla to move down and backward. If a dental implant is placed too early in a patient's development, resorption of the buccal plate could lead to exposure of the implant over time. There is also a spontaneous mesial drift in the teeth over time, but dental implants do not participate in this.⁷ A dental implant in the lateral region would inhibit this drift laterally, which could lead to an asymmetrical arch with an anterior implant that ends up positioned too far palatally.⁸ The vertical growth of the face is the last of the three dimensions to complete its maturation process.⁹

A healthy 19-year-old female patient with a high smile line initially presented with four upper anterior teeth that had been heavily restored with composite resin over the years (Figure 1). She reported that she did not like the appearance of these teeth and also complained that she experienced occasional tenderness associated with tooth No. 10 ever since she had recently undergone endodontic treatment on tooth No. 9 (Figure 2). A full case workup was performed, and four layered lithium disilicate restorations (IPS e.max^® Press [A1], Ivoclar) were completed on teeth Nos. 7 through 10 (Figure 3).

At one of the patient's scheduled review appointments, she mentioned that she was still experiencing intermittent pain associated with tooth No. 10 and that it was becoming more regular and intense. A small field of view cone-beam computed tomography (CBCT) scan of the area was acquired, and a vertical root fracture was discovered with an associated radiolucency. It was determined that tooth No. 10 would need to be removed, so possible treatment options were presented along with the pros and cons of each option. Removable options, which included a flipper denture or a Hawley-style removable passive appliance with a tooth fixed to it, were discussed as transitional or definitive treatment options. The fixed options presented included a resin-bonded bridge (direct or indirect), a 3-unit bridge, and an implant-supported crown. After deliberating, the patient and her parents decided on a dental implant. They were informed that for this to be a predictable and esthetic option, the completion of skeletal growth would need to be confirmed and that meticulous planning would need to be performed.

Due to the age of the patient, the dental team had a duty of care to ensure that dental implant surgery was not performed prematurely. To confirm the completion of skeletal growth, the patient was sent for a left hand and wrist radiograph (Figure 4). This would reflect the maturity of many different bones simultaneously and permit assessment of the development of growth plates.¹⁰ The patient's radiology report demonstrated that her epiphyseal plates were fused at all sites, which is consistent with the changes visible at adult maturity, so she was cleared to receive a dental implant.

A small field of view CBCT scan was obtained of the patient's anterior maxilla, and the decision was made to follow an immediate implant placement protocol.¹¹ This included the removal of tooth No. 10, curettage of the area to remove any granulomatous tissue, and placement of a 3.5 mm by 15 mm dental implant (NobelActive^® NP, Nobel Biocare). Because sufficient insertion torque was achieved, the patient was immediately temporized using the existing clinical crown with its existing porcelain restoration, relined and retrofitted on a temporary abutment (Temporary Abutment Engaging Conical Connection NP, Nobel Biocare) with flowable composite resin and polished to a high sheen. The temporary restoration was placed in infraocclusion with very light interproximal contacts.

To fill the space between the implant and the buccal bone plate, a xenograft material (Bio-Oss^®, Geistlich Pharma) was placed, covered with a collagen barrier membrane (Bio-Gide^®, Geistlich Pharma), and stabilized with a monofilament suture (5-0 Prolene^® P-3 13 mm 3/8c Reverse Cutting, Ethicon). The patient's upper anterior teeth demonstrated a thin tissue phenotype, so a de-epithelialized connective tissue graft was harvested from her left palate, placed, and stabilized with the same monofilament suture that was used to stabilize the collagen membrane. The graft was harvested from the patient's left palate to enable her to still use the right-hand side of her mouth during the healing process.¹²

After 2 weeks, the soft tissue was evaluated (Figure 5), and the sutures that stabilized the connective tissue graft were removed. The soft tissue around the implant was evaluated every few weeks over the next several months to ensure uneventful healing (Figure 6 and Figure 7). Four months later, the process of shade selection commenced, and impressions were taken for the definitive crown.

Effective communication with the dental laboratory was key to achieving the desired esthetic outcome. Dentists often forget that although they see patients in real time, including the relationship between their teeth, the frame created by their lips, and the role that their complexion plays in this dynamic frame, the laboratory technician does not. Therefore, it is important to send as much information as possible along with the impressions to help the laboratory see the bigger picture and assist in achieving an esthetic result.

Photographs acquired with reflective, cross-polarized light filters and white balance gray reference cards can help to quantify what is seen in a patient's mouth so that the laboratory can get as close as possible to a restoration shade that doesn't appear too different in different light sources. Cross polarization filters mitigate unwanted specular reflections that obscure the fine details of dental structures, and gray reference cards provide a standard reference object for exposure determination, which helps to ensure that the subjective exposure used by the dentist can be accurately reproduced by the dental laboratory. The use of a spectrophotometer can also be beneficial. This complex measuring instrument helps account for light intensity as a parameter of color.

In this case, the dental laboratory technician used a gray reference card (eLAB white_balance gray reference card, Emulation S.Hein) with and without a cross polarization filter (eLAB polar_eyes filter, Emulation S.Hein) to assist in the robust workflow for shade estimation (Figure 8).^13,14 In addition, a gingiva-colored shade tab holder that allows for the placement of three dental shades during photography (Gumy Indicator, Shofu) was used so that the shade of the surrounding soft tissue could be taken into consideration (Figure 9).

Following the protocols developed by the dental laboratory technician and the manufacturers of the photography aids, a beautiful, seamless definitive restoration was fabricated using a titanium base (Medentika Ti-Base, Straumann) and zirconia (Prime Zirconia, Ivoclar) modified with layering ceramic (IPS e.max^® Ceram, Ivoclar) (Figure 10 and Figure 11). The clinician's knowledge of anatomy and immediate implant surgery allowed the final gingival drape to the restoration to look as natural as possible while demonstrating a thicker tissue phenotype (Figure 12 through Figure 14).

The integration of the definitive restoration with the surrounding hard and soft tissue was seamless—something that both the dentist and the patient could be proud of. All of the photographic aids, as well as efficient laboratory communication, helped tremendously in assisting the dental technician in creating a natural looking restoration that could be considered a beautiful piece of art. Recreating form and function should be our aim in restoring broken down or missing teeth, especially in the esthetic zone, but when implants are requested by younger patients, we must also do our due diligence in ensuring that their skeletal growth is complete before initiating treatment.

The author would like to thank Szabi Hant, MDT, for performing the laboratory work for this case.

Hanno Venter, BDS
Accredited Member
American Academy of Cosmetic Dentistry
Diplomate
International Congress of Oral Implantologists
Private Practice
Melbourne, Australia

Taha Akhtar, BDS
Assistant Professor
Department of Prosthodontics
Tufts University
School of Dental Medicine
Boston, Massachusetts

Prosthodontist
Family Health Center of Worcester
Worcester, Massachusetts