April 1, 2014
by Lori Trost, DMD
Replacing enamel, the hardest substance in the body, is no easy task. If enamel is missing–there is a reason. This tooth layer was intended to provide esthetics, mastication, insulation, and phonetics. Daily, enamel is put through rigors – be it an environment that fluctuates in response to changing pH introductions or perhaps a malocclusion that over time has been altered enough to create a damaging situation. Whatever the cause of absent enamel, it must be identified and restorative considerations must move forward so that the cause is completely treated, and a healthy environment can return and be maintained.
Various presentations are responsible for contributing to enamel loss or absence. The leading cause of affected enamel is caries, a transmittable, infectious disease of teeth caused by acid producing bacteria. Another condition resulting from pH unsteadiness is erosion. This irreversible enamel loss originates from the interruption of the natural oral balance and neutralization is unable to provide a long enough recovery period to return mineral content to repair the surface. Enamel erosion is directly related to excessive soft or fruit drink consumption, dry mouth, diet, acid reflux, medications, and genetics. Additional physical factors affecting enamel may present as abrasion, malocclusion, bruxism, or trauma. As the restoring dentist, one must take into consideration a treatment plan that best answers to the causative affect, resolves the insult, and restores the enamel structure.
Often, by using a combination of dental disciplines–restorative, orthodontics, and minimally invasive dentistry, the fundamental goals of each specific case presentation can be fulfilled. For the dentist, the challenge presents itself in considering treatment options while respecting and preserving tooth structure. For patients, the demands of longer treatment time, finances, and compliance variables can complicate the equation. Ultimately, the quest is to find a balance that satisfies not only the patient’s expectations, but answers to the clinical demands without compromising results.
The following clinical cases represent distinct treatments that were respectful of the loss of enamel; while mindful of preserving as much tooth structure as possible for the final treatment phase and end result. Both cases required eighteen to twenty months of treatment time. It is worth noting that other treatment modalities could have accelerated their treatment; however, those alternatives were never considered once the concept of minimally invasive dentistry was embraced by the patients.
A 58-year-old female presented with distinctive facial erosion and sharing a long standing history of drinking lemonade. As shown in Figure 1, even though the erosion was extensive she had no sensitivity and her malocclusion was of concern. After maintaining one year of monitored recare visits, dietary counseling, and beverage discontinuance, the patient was ready to move forward in restoring her smile. Central to her successful treatment outcome was her understanding of the damage the acidic environment had caused and the lifetime commitment to continue to modify her beverage selections.
Several treatment options were offered to the patient. Due to the extent of enamel loss along with the malposed teeth, full contour restorations did not offer a satisfying option without first addressing her malocclusion. The probability of endodontic treatment would be real, as would the likelihood of increased sensitivity. After much discussion, the most conservative approach was chosen that would utilize and respect the remaining enamel. By first correcting her alignment for function, the appropriate tooth sizes and shapes would be allowed to be re-created. The choice of first correcting occlusion is paramount because it sets the stage for excellent esthetic options that can follow (Figs. 2 & 3).
Another variable in presenting this treatment plan to the patient was the timeline. Today, patients want to hurry in to a “quick fix”. This urgency from their perspective can often lead to differences in expectation, causing a potential conflict. In cases such as this, it is imperative that the patient completely understands and agrees (in writing) to terms of an estimated timeframe of treatment. This author’s opinion is to always add two to three months of treatment time to the total, and if completed sooner, both patient and dentist are the winners!
The patient underwent orthodontic treatment using Invisalign for 16 months. Figure 4 illustrates her final occlusion. Her overbite improved greatly–allowing proper restorative space for the mandibular anteriors as well as re-establishing her canine guidance. The patient not only complied with treatment but also was meticulous with her home-care and continuing her natural oral balance.
After four months of orthodontic maintenance, the patient was ready to begin her next phase of treatment. Restoratively, two sections of treatment were planned – first, the mandibular arch followed by the maxillary arch.
Due to a request by the patient, the initial mandibular anterior teeth treatment was modified. Rather than complete permanent facial veneering on these teeth as originally planned, due to finances, chairside provisionals were bonded. Working model impressions were fashioned to create a final wax-up for restored height and contour for the mandibular anterior teeth. Releasing spray was used to coat the wax-up and a clear matrix material (TempSpan Clear Matrix) was used to capture the future restoration shapes. These teeth were not prepared at this point thus allowing the final preparations to be unaltered for the final preparing date. Chlorhexidine scrub was applied and then rinsed. Each facial surface was agitated for 20 seconds with a self-etching bonding agent (Elect), lightly aired, and then light cured for ten seconds. Using a B1 shade, TempSpan was syringed into the clear matrix and positioned onto the teeth in their natural presentation. Light curing was possible through the clear matrix to set the provisional material within one minute. The matrix was removed and final light curing was completed against the tooth surface. The
provisional group was adjusted and polished (Fig. 5).
The maxillary restorative phase was set to begin. Bilaterally, first premolar to first premolar were prepared for veneers. Veneers were chosen to conserve tooth structure as well as to maintain the newly established occlusion, especially considering the lingual aspect. A final PVS impression (Aquasil) was taken and a bite registration made. Temporary veneers were made as a complete unit following the above mentioned technique, however they were not bonded to tooth structure. As shown in Figure 6, the temporaries in the pre-polish and glaze phase. Care was made to ensure the occlusion, phonetics, and smile line met the treatment plan and patient expectation.
Feldspathic porcelain veneers were created using a direct refractory technique for stacking porcelain. This highly customized approach to restoring her enamel was chosen because it allows for protection, function, and beautiful coloration in the final results. Each veneer was prepared at the lab for direct insertion.
At last … the results of planning and compliance were realized at the insertion 20 months later. The patient was anesthetized and the temporaries were removed. The preparations were cleaned with a pumice slurry, rinsed, and isolation achieved. Each veneer tooth surface was etched for 15 seconds and then rinsed for ten seconds. Care was made to leave the tooth surfaces moist. The adhesive (Adper Single Bond Plus, 3M ESPE) was applied in two coats to the etched dentin and enamel surfaces for 15 seconds in a scrubbing type fashion, then air thinned for five seconds. A single adhesive coat was applied to each silane treated veneer and lightly air dried for five seconds. Translucent veneer cement (3M ESPE) was placed in each veneer, two at a time–ready for placement, starting with the centrals. A tack cure using a small diameter LED light was used to secure the gingival seal. Once all the veneers were seated and tack cured, final light curing was completed for 40 seconds, from both the facial and linguaI surfaces using a large diameter LED tip. In Figure 7, the final result as shown. The patient was extremely pleased. Moving forward the patient anticipates her readiness to complete the final mandibular restorative treatment.
A 56-year-old male patient presented with malposed occlusion. “Worn, crooked teeth” were his chief concern. Upon closer evaluation, due to his occlsion, his enamel was severely affected–almost accentuating the angulation and mis-alignment of his teeth (Fig. 8).
The patient had excellent homecare and periodontal status, making him a good candidate for clear aligner orthodontic therapy. Treatment became clear in two phases: first, align the teeth and then consider options to restore the missing enamel. Invisalign was chosen for orthodontic alignment that consisted of 14 months treatment.
A significant benefit during the Invisalign treatment-planning phase was the ability to forecast tooth and root alignment, given the amount of absent enamel. The final esthetic outcome hinged on allowing the treatment to be designed for not only proper function, but also for the creation of golden proportions for the final restorative phase. Completed treatment is shown in Figure 9. The patient was held in an orthodontic maintenance phase for five months.
After presenting options of laboratory prepared veneers, chairside veneers, or enamel replacement bonding – the patient was most comfortable with the most minimally invasive approach of bonding. At the end of month nineteen, the patient had chairside bonding performed. Tooth preparations consisted of placing 3mm long bevels on the facial surfaces of the maxillary laterals and centrals as well as the involved mandibular anteriors. A selective-etch technique was applied for 15 seconds to the enamel. This was followed by a 20 second agitation scrub on dentin and enamel surfaces using Elect bonding agent, then light cured for 10 seconds. TPH Spectra LV, shade A1 was sculpted into place to extend the missing line angles and incisal edges of each tooth and then appropriately light cured. All restored teeth were adjusted and polished using a variety of discs and cups, followed by diamond polishing paste. The completed case (Fig. 10).
The ability to provide dental restorations that deliver esthetics, performance, and longevity regarding specific tooth structure replacement has come to the forefront in practices today. Although clinicians have more treatment resources and possibilities than ever, restoring the integrity of the original enamel structure as well as the environment it functions in needs to remain central to treatment planning.OH
*The author would like to thank Dan at Becker Dental Lab for his expertise in the veneer case.
Lori Trost, DMD maintains a private practice in Columbia, IL merging contemporary esthetic dentistry with a minimally invasive approach to patient care. She has authored a wide variety of articles found in numerous dental publications, is a clinical evaluator and consultant, and an ADA Shils Foundation recipient for Leadership. Dr. Trost is an accomplished lecturer and presents on a regular basis throughout the United States and Canada sharing her vision and approach to everyday dentistry that is informational, motivational, and refreshing. You may co
ntact her at: email@example.com. Oral Health welcomes this original article.