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COSMETIC DENTISTRY: Options for Non-surgical Treatment of a Skeletal Class III Malocclusion

April 1, 2000
by Antonio Mancuso, DDS, FAGD


Today’s revolution in aesthetic dentistry allows clinicians to offer patients a multitude of treatment options. With a variety of new materials and enhanced application techniques, we have numerous methods to improve the appearance of the anterior dentition. In particular, the tooth-coloured, biocompatible materials currently available enable us to achieve restorations that are indistinguishable from natural dentition. With these innovations, dentists now have the opportunity to use modern aesthetic materials and modalities on previously uncharted areas of conventional dentistry. The following case report describes how porcelain veneers and fixed orthodontics can be used to provide non-surgical treatment for a skeletal class III malocclusion.

CASE HISTORY

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A 39 year-old female wanted to improve her smile. She was unhappy with her “short teeth that didn’t show very much” in her smile (see Figures 1-5). The patient explained that she had felt this way for a long time. She had a history of fixed simple orthodontics to correct a maxillary midline diastema at age 30. At the time of examination, a lingual bonded retainer between her maxillary central incisors was still present.

A clinical examination disclosed that all teeth, except #18 and #28, were present. The patient had excellent oral hygiene, and a soft tissue examination confirmed that all tissues were within normal limits. Radiographic examination revealed that the alveolar support was normal. Previous restorative care was limited to conventional amalgam and composite restorations. The patient had a class III molar relationship with no overjet and no overbite. There was a 2mm maxillary midline deviation to the right.

An orthodontic evaluation revealed the patient had a skeletal class III malocclusion with bilateral posterior crossbites extending anteriorly to the lateral incisors. The central incisors exhibited an end-to-end relationship. The lower incisor to mandibular plane angle was 93, SNA-75, SNB-76 and ANB of -1,. Consultation with an oral surgeon confirmed that comprehensive orthodontic treatment, combined with maxillofacial surgery, was required to achieve an ideal result. However, the patient was reluctant to enter into a lengthy treatment plan that involved orthognathic surgery. Therefore, we discussed alternative modes of treatment.

TREATMENT PLAN

After much discussion with the patient, we agreed to four treatment goals:

To lengthen the perceived short anterior teeth;

To develop an ideal overbite and overjet relationship;

To provide a more prominent smile that included better lip support; and,

To complete the work in the least amount of treatment time.

We agreed to proceed with fixed orthodontic mechanotherapy on the mandibular arch to consolidate the anterior segment. Placing ten IPS Empress porcelain veneers (Ivoclar; Amherst, NY) on teeth #15 to #25 to correct the crossbite would follow this treatment.

With the treatment goals in mind, a diagnostic wax-up was performed to evaluate the amount of crown labialization that would be required. The current molar relationships could remain as is without compromising the end result. A smile analysis determined the maxillary incisors could be increased from 8.5 mm to 11 mm in length, since the current width-to-length ratio was almost 100%. It is important to note that in labializing the maxillary teeth an increase in arch length occurs; therefore, clinicians must respect the golden proportion rule to ensure an ideal aesthetic result.1

Stage 1: Orthodontic work

Orthodontic brackets were bonded on the mandibular teeth from #36 to #46 using a Roth prescription to enable the use of straightwire mechanics. Over the course of the next three months, the mandibular anterior segment was consolidated and rotations corrected using elastomerics (see Figures 6-7).

Stage 2: Maxillary Preparation

After administering local anaesthetic to the patient, the shade and enhanced mould for the final restorations were selected using the chromascope shade guide (Ivoclar; Amherst, NY), and the smiles mould guide.2 Teeth #15 to #25 were prepared for Empress porcelain veneers.

To meet the treatment goal of increasing the maxillary arch length, we took an unconventional approach to preparations. A definitive chamfer was placed on the labial gingival margins. The remainder of the labial preparation was minimal to allow only for draw of the restoration. Next, an aggressive lingual preparation allowed for the labialization of the porcelain (see Figure 8). This step prevented bulky teeth and helped to achieve the overall aesthetic goals. The lingual aspects of the preparations were finished with a chamfer. Using a diode laser (Premier; Irvine, CA), the gingival tissue was sculpted, where required, to achieve gingival symmetry, contour, and zenith. Finally, the treated tissue was cleaned with H2O2 and a tincture of myrrh was applied.

Following preparation, the teeth were carefully examined, debrided, and rinsed with chlorhexidine. All finish lines were inspected, and any sharp edges refined. To ensure clear communication with the lab the following were provided:

photos of the stump shades next to the prepared teeth. Taking the stump shades prior to final impressions avoids desiccation and inaccurate selection.

a polyvinyl siloxane impression along with a stick bite and facebow. This step helps the technician to fabricate the incisal edges of the restorations parallel to the horizon.

Stage 3: Provisionalization

Using the diagnostic wax-up as a guide, a putty matrix was created that extended one tooth past the prepared teeth on either side. This putty matrix was then trimmed with a #15 scalpel closely following the labial gingival contours. On the palatal side, the putty matrix was trimmed to within 3-5 mm of the intended finish lines of the prepared teeth. Ensuring accurate trimming reduced the labour-intensive clean-up portion of the preparation appointment. However, a thorough clean-up job is always necessary. Clinicians who rush through this step face less than ideal results. If proper care and attention is not observed at this point of provisionalization, then at the insertion appointment, the clinician could be faced with hemorrhagic tissue leading to a compromised result.3,4

Next, the putty matrix was placed intraorally to determine proper orientation and to confirm that enough putty had been trimmed away, especially on the palatal side. Using the filtrum as a guide, the midline was marked on the putty to decrease any guesswork on the position of the matrix once it was loaded with the temporary material.

The prepared teeth were cleaned with chlorhexidine and dried. Optibond primer (Kerr; Orange, Ca.) was applied to the preparations to help reduce post-operative sensitivity. This step also minimized any black line staining that often is seen when the provisionals are removed. This “black scuz” is a result of bacterial byproducts.

For this case, Luxatemp (Zenith; Englewood, NJ) was the preferred temporary material. To avoid any air bubbles in the provisionals, the Luxatemp was injected into the putty index starting on one side and slowly injecting to the other side without raising the tip of the applicator (see Figure 9). Clinicians should note that they have up to two minutes working time before the Luxatemp becomes tacky. Next, the putty matrix was placed in proper position using the midline marking and occlusal stops of the teeth on either side of the most distal preparations. The dental assistant held the matrix in place while any extruded excess was removed with a cotton roll. A rubber tip stimulator was used to remove any excess Luxatemp along the gingival margins. Special attention was given to interproximal surfaces. After all the excess had been removed, the matrix was held for an additional two minutes to further the polymerization of the provisional.

Once hardened, the putty matrix was lifted off with a scaler, leaving the temporary restorations secured to the dentition. A 7901 carbide bur was selected to trim
along the labial margin and interproximal surfaces. This trimming gave the tissue an ideal healing environment during the provisionalization period. Note that clean-up time was minimized by scalloping the putty matrix beforehand and by using a rubber tip to remove excess material in the labio-gingival embrasures.

It is important to note that the provisional was checked in centric occlusion and in both right and left lateral excursions. Voids were easily corrected using either a small amount of Luxatemp or using Revolution (Kerr; Orange, Ca.), a flowable composite of comparable shade. To mimic natural dentition incisal characterization was created using a diamond disc #104 (Brasseler; Montreal, PQ). Finally, once the provisional procedure was finished, the provisionals were polished using polishing discs and proxyt diamond polishing paste (Ivoclar; Amherst, NY) to ensure a final lustre.

Post-op instructions to the patient included:

regular use of an oral rinse of the patient’s choice to aid in minimizing gingival irritation; and

use of a rubber tip stimulator.

Laboratory instructions

Clear communication with the lab is crucial to ensuring a successful end result. The prescription for the fabrication of ten IPS Empress restorations included a detailed description of shading using a colour-mapping diagram with designation of incisal translucency and incisal halo. Instructions also included amount of surface texture, stump shades, length of central incisors, and mould selection.

In addition, the lab received the following records:

initial study models,

diagnostic wax-up,

final polyvinyl siloxane impressions,

all photographic records,

stick-bite registration,

facebow registration, and

alginate of provisionals.

As in any restoration case, once the final restorations were returned from the lab they were visually inspected and placed on the laboratory model to ensure complete seating and adequate contacts. Next, the margins were inspected for fit and the internal surfaces were inspected for a uniform, frosted appearance.

Stage 4: Try-in

After administering local anaesthetic, the temporary restorations were removed. The teeth were cleaned using chlorhexidine and pumice, and then rinsed thoroughly. The restorations were tried-in two at a time checking for fit and adequate contacts. Slight modifications in the contacts were made and the surface repolished using the Brasseler Dialite porcelain system. All ten restorations were tried in simultaneously to ascertain full seating. These restorations were removed and reseated with Variolink try-in gel (Ivoclar; Amherst, NY) so that the patient would be able to see the intended results. After the patient had approved the try-in, we moved on to the cementation stage.

Stage 5: Cementation

Firstly, the restorations were washed with water. Next, an application of a 37% phosphoric acid gel etchant to the internal surface acted as a decontaminating agent. The etchant was rinsed off immediately and air-dried. Finally, the internal surfaces were silanated for one minute and dried.

A rubber dam was placed with #12A and #13A clamps on teeth #16 and #26 employing the anterior trough technique. One assistant lined the restorations with Optibond 2Fl bonding agent (Kerr; Orange, CA) and loaded them with Variolink’s translucent shade base only. To prevent premature polymerization, the restorations were protected from the light. At the same time, a second assistant was used to prepare the teeth. The teeth were:

washed with chlorhexidine,

acid etched with 37% phosphoric acid,

washed and lightly dried,

rewetted with Tublicid Red,

blot dried and

primed with multiple coats of primer (Kerr; Orange, CA)

Before applying Optibond 2Fl to the teeth we turned off the overhead light to prevent premature polymerization of the bonding agent.

The restorations were placed two at a time starting with the centrals. Excess labial cement was removed with a rubber tip (Butler; Guelph, Ont.) and then tacked on using a small 3mm Maxlight curing tip (Caulk; Milford, DE) for five to ten seconds. Floss, used in a labial to palatal direction, helped to remove any excess material along the interproximal surfaces. This sequence was repeated with the lateral incisor and cuspid and then with the premolars both on the right and the left side. Applying a thin layer of glycerin to the margins prevented formation of an air-inhibited layer. The restorations were then cured with an Argon laser (Premier; Irvine, CA).

Stage 6: Finishing

Excess flash was removed by using a 7901 finishing bur along with a fine ET6 diamond finishing bur (Brasseler; Montreal, PQ). A proxydisc (Alpha-Dent; Chicago, IL) and Horico separators (Pfingst & Co; South Plainfield, NJ) were used to separate joined restorations.

The occlusion was evaluated and adjusted using a large round diamond with copious water. Finishing diamonds were used for final occlusal adjustments in all excursions. These final adjustments were an important step to ensure that the restorations provide the proper anterior guidance and not cause fremitus in centric occlusion.5 The Dialite polishing system and proxyt diamond polishing paste provided the final polishing necessary for a winning smile. Careful evaluation of the interproximal and cervical gingival areas using dental floss ensured adequate contacts and the absence of gingival overhangs.

TREATMENT GOALS ACHIEVED

The patient requested aesthetic improvement of her smile. This was achieved using a combination of fixed orthodontic mechanotherapy on the mandibular arch and ten IPS Empress restorations in the maxillary arch. A model of the final treatment shows that the arch width from tooth #13 to #23 increased from 32mm to 36mm compared to the pre-treatment study model (see Figures 10-11). The lengths of the central incisors were increased from 8.5mm to 11mm and the width/length ratio was changed from nearly 100% to 77%.

The resulting increase in maxillary arch length by 4 mm and constriction of the mandibular anterior segment achieved a satisfactory result for both the patient and the clinician. The patient was very pleased with the final result having met all the treatment goals (see Figures 12-18).

In today’s aesthetically demanding society, patients are looking for pleasing results in a short timeframe. Clinicians must be innovative and consider alternatives to traditional modalities. Aesthetic materials are continuously being tested to greater limits with these modalities as we shift our paradigms in clinical practice.

Acknowledgements

The author wishes to thank Dr. W. Dickerson and Dr. C. Pescatore of the Las Vegas Institute for Advanced Dental Studies for their help in this case. Also, thank you to Dave Stoleman from MicroDental Lab for creating the restorations.

r. Antonio Mancuso maintains a full-time general practice in Welland, ON, with an emphasis on aesthetic dentistry. He is the course director for Millennium Aesthetics, a live hands-on Aesthetics program that he conceived and developed. Dr. Mancuso is Membership Director for the Ontario Academy of General Dentistry. He graduated from the University of Toronto School of Dentistry in 1985.

Oral Health welcomes this original article.

REFERENCES

1.Dickerson, Dr. W.G. and Hornbrook, Dr. D.S., Anterior Esthetic Program, Las Vegas Institute for Advanced Dental Studies, Sept.- Oct. 1997.

2.Dickerson, Dr. W.G., Smiles Mould Guide, Advanced Anterior Esthetic Program, Las Vegas Institute for Advanced Dental Studies, April-May 1998.

3.Clich, Gerard J., D.D.S., “Provisional Restorations in Anterior Procedures,” Dentistry Today, Vol. 13, No. 7, July 1994. Pages 32-37.

4.Small, Bruce W., D.M.D., F.A.G.D., F.I.C.D., “Predictable Porcelain Laminate Veneers,” Dentistry Today, Vol. 15, No.4, April 1996. Pages 36-41.

5.Terry, Douglas, D.D.S., “IPS Empress Crown,” AACD Journal, Winter 1999. Pages 52-59.


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