Treating Diminutive Maxillary Lateral Incisors in Teenagers
Resin-based composite and ceramic veneers offer two possibilities for coronal augmentation
Theodore P. Croll, DDS | Ernest J. Dellheim, DMD | Steven Jefferies, MS, DDS, PhD
Diminutive permanent maxillary lateral incisors, which are also referred to as "peg laterals" or "lateral incisor microdonts," pose treatment challenges for dentists and orthodontists. For the dentist, concerns include the patient's appearance, anterior teeth spatial relationships, incisal contacts in function, proximal contacts with the central incisors and canine teeth, and related stable retention after completion of orthodontic treatment. The status of the roots of diminutive lateral incisors needs to be considered as well. Sometimes, these roots are so overly short and narrow that, considering the long-term prognosis, extraction and orthodontic canine migration or implant replacement may be reasonable options. Alternatively, however, lateral incisor coronal enlargement using directly applied and bonded tooth-colored, resin-based composite can be used to imperceptibly restore the form, function, and appearance of a normal lateral incisor.1-7 In older teens, the same result can be achieved using a bonded ceramic veneer or a three-quarter or full-coverage crown.8,9 This article examines three case reports involving the treatment of diminutive lateral incisors. The first two describe the fabrication of crowns using resin-based composite and the placement of bonded ceramic veneers, respectively, and the third details the follow-up of a patient who underwent composite coronal augmentation of both diminutive maxillary lateral incisors 26 years earlier.5
Case Report 1
A 15-year-old female patient who had diminutive maxillary lateral incisors presented to the practice after completion of her orthodontic treatment. For her retention phase, the orthodontist had bonded interproximal composite "angel wing retainers" to maintain the position of those teeth (Figure 1). These angel wings were cut away prior to the initiation of treatment (Figure 2 and Figure 3), which began with restoration of her diminutive maxillary right lateral incisor.
After considering the lighter shade of the approximating central incisor and more yellow coloration of the approximating canine tooth, the dental assistant and dentist selected an appropriate shade of resin-based composite (Filtek™ Supreme Ultra Universal Restorative [B1B], 3M). A small sample of the selected composite was polymerized and used as a shade guide.
Following infiltration of a local anesthetic to achieve soft-tissue anesthesia, a retraction cord was placed to reveal more of the enamel surface at the gingival margin and control any sulcular fluid. All of the tooth's axial walls were then roughened slightly with a diamond bur, and thin, 0.0015-in (0.0381-mm) custom-contoured stainless steel matrix strips (Strip-T Matrix System [Anterior Small], Denovo Dental) were placed and secured to the adjacent teeth with bonded composite (Figure 4). These thin metal strips were used instead of a thicker acetate strip crown form because the thickness of the strip crown form may have resulted in mesial and distal open contacts after polymerization of the composite and removal of the form.
With the strips in place, a 40% phosphoric acid gel was painted over the entire coronal surface and agitated with a small brush for 20 seconds. It was then completely rinsed off with an air/water spray, and the tooth was carefully dried with an air syringe (Figure 5). The frosted appearance of the surface provided evidence that it was ideally etched. Next, a resin bonding agent (Adper™ Prompt™ L-Pop™ Self-Etch Adhesive, 3M) was liberally painted over the entire crown surface and thinned out with a gentle air spray (Figure 6). The bonding agent was then exposed to a curing light beam for a total of 20 seconds (10 seconds each from the labial and palatal aspects).
After the bonding agent had been light cured, an initial increment of the resin-based composite was injected onto the labial surface (Figure 7). Hand instruments were used to compress the soft composite into the labial surface while taking care to completely fill the tooth/matrix strip interface (Figure 8). Once placed, the composite was photopolymerized with a 30-second exposure to the curing light beam (1,100 mWcm2). The labial portion of the restoration was completed by injecting a second increment, which was also compressed into place and then light-cured for 30 seconds. For the lingual surface, two increments of composite were placed, compressed, and light cured using the same protocol. Extra care was taken to avoid air entrapment.
The matrix strips and the bonded composite used to stabilize them were removed. Using high- and low-speed diamond burs, finishing burs, and aluminum oxide disks, the coronal form was then sculpted, finished, and polished (Figure 9). The total treatment time for the diminutive maxillary right lateral incisor was about 75 minutes. At a second appointment, the patient's maxillary left lateral incisor was restored in the same manner.
The maxillary right lateral incisor was photographed 1-year postoperatively (Figure 10), and new photographs and periapical radiographs were acquired 4 years after treatment (Figure 11 through Figure 13). During the fifth postoperative year, the patient related that she had used over-the-counter tooth whitening strips for about a week but ceased after she noticed that the color of the lateral incisor was not changing in concert with the color of the "front teeth" (Figure 14).
Case Report 2
A 15-year-old female patient who had completed her orthodontic care was having the positions of her diminutive maxillary lateral incisors maintained with a vacuum-formed interim retainer for treatment to enlarge them (Figure 15). After evaluating the incisal clearance in mandibular excursions, conservative enamel reduction for veneer placement was performed with a water-cooled diamond bur (Figure 16). A suitable porcelain shade was selected based on the shades of the adjacent canine and central incisor (Figure 17), and an impression was made with polyether material (Impregum™ Super Quick Polyether Impression Material, 3M). No provisional restoration needed to be placed. After laboratory processing of the veneer, which was fabricated from lithium disilicate (IPS e.max® Press, Ivoclar Vivadent), the patient was recalled to the office. The enamel was acid-etched, a universal adhesive (Prime&Bond elect®, Dentsply Sirona) was applied, and the veneer was bonded into place with a light-cure resin luting cement. During a routine checkup, the veneer was photographed 20 months after placement (Figure 18). The patient's diminutive maxillary left lateral incisor was also restored with a bonded ceramic veneer in the same manner.
Case Report 3
A 38-year-old female patient agreed to return to the practice for follow-up at the request of the lead author. Twenty-six years prior, when the patient was 13 years old, she had undergone coronal enlargement of both diminutive maxillary lateral incisors using a resin-based composite (Charisma®, Kulzer LLC) in a case with 6-year follow-up that was published in 2002 (Figure 19 through Figure 22).5 She reported that the restored teeth had required no additional clinical intervention since the time of composite crown placement except for periodic repolishing (Figure 23 and Figure 24). In addition, the brown stain line at the margin of the maxillary left lateral incisor was of no concern to the patient. She not only said that she had never noticed it but also declined the offer to have it removed and the margin resealed.10
Discussion
The treatment rendered for all three of these patients demonstrates the successful results that can be achieved using acid-etched enamel/adhesive resin bonding techniques. Although some clinicians have expressed concerns about placing ceramic veneers, as well as full-coverage or three-quarter crowns, too early in the adolescent years because passive eruption may expose the facial margins, the second case report suggests that certain patients in their mid-teens may be treated successfully with indirect porcelain crown augmentation if care is taken to sufficiently extend the labial cervical margin into the gingival sulcus. In the discussion section of a previously published case report that documented a 32-year-old Class IV maxillary incisor repair and subsequent treatment, Croll and Jefferies succinctly reviewed the evolution of resin-based composite dental restorative materials, noting that "the latest formulations developed in the nanofill class of restorative materials...can offer improved esthetics, reduced polymerization contraction, and enhanced mechanical characteristics."11
The resin-based composite restorations placed in the first and third case reports described in this article were all composed of only one shade of material; however, they were all esthetically acceptable to the patients. When one studies the permanent anterior teeth from a vantage point of 6 inches away under direct lighting, which is what people do when they peer at their own teeth in a mirror, the influences of enamel translucency and all aspects of the color variations in different sections of the teeth can be obvious. However, when those same teeth are observed from further distances, such variations in shading become less obvious, and at a conversational distance, they become irrelevant. This is because teeth are subject to the normal facial movement of talking and shadowing by the lips. Furthermore, people are mostly looking at each other's eyes in such circumstances.
In the first case report, color matching was excellent at 4 years (Figure 11 and Figure 12), and the shades of both maxillary lateral incisors were still quite acceptable to the patient at 5 years, 7 months, even after she had slightly lightened her maxillary central incisors with over-the-counter tooth bleaching strips (Figure 14). In the third case report, the resin-based composite crown augmentations maintained their shades and were still acceptable to the patient after 26 years, even under close evaluation (Figure 23 and Figure 24).
The bonded coronal augmentation treatments described here provide excellent examples of how the morphology, alignment, and color of restored teeth have been greatly advanced by adhesive dentistry. Decades after the acid-etched enamel bonding method was introduced, it still represents the most reliable means to create a long-term, stable, micromechanical adhesive bond to enamel. It should be noted that the correction of esthetic challenges with enamel bonding was made feasible by the development of light-polymerizable resin-based composites that contain higher molecular weight monomers, such as Bis-GMA, and undergo less shrinkage as well as the inclusion of "diluent" methacrylate, which enabled the incorporation of silanated ceramic and glass fillers to enhance filling material strength and versatility. In addition, the introduction of camphorquinone as a polymerization initiator that utilizes visible light energy in the high energy blue range of the spectrum resulted in the ability to command-cure, extended working times, and further enhanced color stability over time—often for many years.
The results attained in these treatments are representative of what can be achieved with many brands of resin-based composites, bonding agents, and ceramic materials available to modern dentists. In modern adhesive dentistry, excellent clinical results rely significantly on the operator's artistic proficiency in both the precise execution of the bonding technique and the careful, appropriate handling of the chosen materials.
Disclosure
The lead author has a financial interest in the Strip-T Matrix System by virtue of an agreement with Denovo Dental. None of the authors have a financial interest in any of the other products mentioned in this article, and they have neither received nor will receive remuneration of any kind for its production.
About the Authors
Theodore P. Croll, DDS
Clinical Professor
Case Western Reserve University
School of Dental Medicine
Cleveland, Ohio
Adjunct Professor of Pediatric Dentistry
University of Texas Health
Science Center at San Antonio
School of Dentistry
San Antonio, Texas
Clinic Director
Cavity Busters Doylestown
Doylestown, Pennsylvania
Ernest J. Dellheim, DMD
Adjunct Clinical Associate Professor
AEGD Program
Temple University
Kornberg School of Dentistry
Philadelphia, Pennsylvania
Private Practice
Narberth, Pennsylvania
Steven Jefferies, MS, DDS, PhD
Guest Researcher
Department of Applied Materials Science
Uppsala University
Uppsala, Sweden
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