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Feldspathic Porcelain Veneers: Teamwork Between Prosthodontist and Orthodontist


November 9, 2017
by Goth Siu, BHSc, DMD, MS, Cert. Prostho., FRCD(C), FACP; Nima Mir, BSc (Hon), DDS, MSc, FRCD(C)

Communication amongst clinicians in interdisciplinary cases is crucial for proper orchestration and execution of procedures. Careful diagnosis and treatment planning is required for successful outcome.The clinician must examine the face and the smile comprehensively to diagnose the problems. There is a plethora of information in the literature about macro and microaesthetics of the smile that can assist.1,2,3 The position of the anterior teeth in relation to the nose, lip and chin can create dramatic changes in a person’s smile. To achieve cosmetically optimal results, often teeth can be orthodontically moved to a desirable position in the arch before prosthodontic treatment to enhance tooth form and colour.

The patient described here, a dentist himself, was unhappy with the progress he had experienced after one and a half years of Invisalign treatment by another clinician. The chief complaint was a dislike of his smile. During the course of that treatment, interproximal reduction on the lower teeth and improved alignment of the arches were achieved. He had orthognathic jaws and Angle’s Class I occlusion with minimal overjet and overbite (Fig. 1). Bolton analysis showed a tooth size discrepancy with mandibular excess. Small maxillary lateral incisors could be identified in the arch (Figs. 2-3). In a consonant smile arc, the curvature of the maxillary incisors and canines was parallel to the lower lip.1 The patient clearly had a non-consonant or flat smile line (Fig. 4). Moreover, there was minimal gingival display during smiling. The right amount of gingival display would resonate a more youthful and pleasing smile.

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Figure 1

Initial front view.

Figure 2

Initial maxillary arch.

Figure 3

Initial mandibular arch.

Figure 4

Initial smile.

Figure 5

Frontal view after orthodontics.

Figure 6

Smile after orthodontics.

Figure 7

Intramural view of anterior teeth after orthodontics.

Figure 8

Smile with mock-up.

Figure 9

Close view of smile with mock-up.

Figure 10

Mock-up with retractors (original photo is of the full face but was cropped to hide the patient’s identity).

To improve the smile and establish a normal overbite and overjet, one objective was to increase the mesio-distal dimension of the maxillary incisors, thereby improving the tooth size discrepancy problem. Alternatively, in an individual with large lower teeth, small face and facial features it may be prudent to maintain the size of the upper teeth and reduce the width of mandibular teeth to rectify the bolton discrepancy. The decision to modify the size of teeth was finalized by involving and consulting with the patient and the prosthodontist. After achieving alignment of teeth with fixed appliances and flexible archwires, open coil springs were placed and activated in between the anterior brackets to create space. The interproximal spaces were measured and documented at each visit. In this process, the teeth have a tendency to tip anteriorly rather than bodily movement, thus it is important to control the root torque in rectangular wires.

Another goal in treatment was to increase the gingival display during smile by extrusion of the anterior teeth while maintaining a normal overbite. This can be achieved by rotating the plane of occlusion clockwise. Gingival aesthetics was obtained by gingival bracket placement on the upper anterior teeth and positioning the brackets with reference to the gingival margins rather than the incisal edges. Vertical elastics with a class II vector were used to help in rotating the plane of occlusion (Fig. 5). The decision to use fixed appliances rather than clear aligners (Invisalign) was to maximize the control over the maxillary anterior teeth. Extrusion of teeth, especially the maxillary lateral incisors, was much more efficient with fixed appliances. While extruding the maxillary anterior teeth, the clinician should always be mindful of its stability. Relapse of anterior open bite correction by extruding the anterior teeth in orthodontics is notorious. The amount of extrusion should be modest with a retention plan.

 

After orthodontic treatment has concluded, the patient was ready for the prosthetic phase of treatment. The patient was unhappy with the colour, shape and size of his anterior teeth (Fig. 6). Due to incisal wear of the maxillary anterior teeth, a mild reverse smile curve was still present after orthodontics. Intraorally, the gingival margin levels appeared ideal and did not require any periodontal treatment (Fig. 7). The lateral incisors were small and a diastema was present between the laterals and centrals, which was planned orthodontically to allow for widening of the laterals. Canine guidance was present at this initial presentation but since the length of the lateral and central incisors was planned to be increased, canine guidance also needed to be increased slightly. After a thorough discussion of alternative treatment options with the patient, which include composite bonding, six anterior minimal preparation feldspathic veneers were planned after the patient completed at home bleaching. In addition to the standard diagnostic information such as periodontal status, caries assessment, occlusal analysis etc., photographs are important for these cases. A smile photo and a full-face smile portrait were taken at the initial appointment in order for a wax-up to be completed. A trimmed putty matrix was used for the intraoral mock up using A1 bisacryl temporary material (Fig. 8). This allowed the patient to visualize the proposed plan before any tooth preparation has commenced. The addition of flowable composite and minor trimming of the temporary material was performed to create the ideal aesthetics that was approved by the patient (Fig. 9). A retracted full-face photo was taken in order for any adjustments to the wax up (Fig. 10). This photo was important to ensure the midline and cant was correct relative to the facial midline and the interpupillary line. Once the wax up was finalized, two putty matrixes were fabricated. One for making the provisionals and the other was sectioned and used to measure the amount of tooth reduction. Since the shade of the preparation was close to A1 (Fig. 11), and the plan was to increase incisal length from tooth 13-23, very minimal facial and incisal reduction was needed. 0.5 mm was reduced from the facial and 0.25 mm from the incisal edges. The incisal-third on the lingual surfaces of the canines was also prepared 0.25 mm. The preparation extended interproximally but contact was not broken except between the centrals and laterals where there were existing diastemas. All sharp angles were rounded and preparation margins were equigingival. A stump shade photo was taken with the A1 and A2 shade tabs at the same plane as the preparations in order to select chroma and hue, whereas a black and white photo (Fig. 12) often helps in evaluating the value. Gingival retraction was accomplished with 3M™ ESPE™ Astringent Retraction paste which was ideal due to minimal bleeding and equigingival margins (Fig. 13). Risk of gingival recession was also minimal with the use of the paste. The final impression was taken with light and heavy body Imprint™ 4 VPS impression material. Provisional veneers were fabricated using A1 Protemp™ and a putty matrix (Fig. 14). After trimming extraorally, the provisional veneers were cemented with flowable composite and spot etching (Fig. 15). Minor adjustments were made until aesthetics and occlusion was optimized. AlgiNot™ impressions were taken of the provisionals and cross-mounted as a reference for the ceramist, along with more digital photographs. The final impression was poured in GC Fujirock® (Figs. 16-17) and the refractory cast was poured in G-Cera® Vest. Creation CC porcelain was used with E58 + CLO shades and dentin A1-A2 + E58 + PSO (1:1:2) shades at the cervical regions. Internal stains were added between bakes (Figs. 18-19). The veneers were placed back onto the solid cast to check for contacts (Figs. 20-22). The final feldspathic veneers had a thickness of 0.3-0.5 mm and the resulting translucency was ideal for this situation with a light stump shade (Figs. 23-24). The veneers were tried in intraorally with water. After approval from the patient, the veneers were treated with porcelain etch and Monobond Plus. Pumice was used to clean the tooth surface and etched with 34% phosphoric acid etch. After rinsing and air-dry, Optibond Solo Plus was applied to the preparation, air thinned, and cured. The veneers were cemented with LuxaFlow B1 flowable composite resin. A tacking tip was used to secure the veneer in place before the removal of excess resin. The final cure was done after all excess cement was removed (Fig. 25). Margins, contacts and occlusion were checked. Centric contacts and eccentric movements were also verified. During lateral movement, canine guidance was developed with disclusion of all other teeth, especially the lateral incisors. Even protrusive contacts were at both central incisors. At one-week recall, the soft tissue appeared healthy and indicated a good integration of the veneers (Figs. 26-27). A night guard was planned for the patient to minimize risk of porcelain chipping and fracture. Frequent recalls and maintenance for this patient was crucial to prevent the occurrence of caries, periodontal disease and prosthetic complications. The patient’s initial reverse smile curve had been improved with the use of orthodontics and feldspathic veneers (Figs. 29).

Figure 11

Shade photo (A1 and A2 tabs).

Figure 12

Black and white shade photo.

Figure 13

Preparations with retraction paste.

Figure 14

Provisional veneers.

Figure 15

Smile with provisional veneers.

Figure 16

Master cast.

Figure 17

Master cast.

Figure 18

Porcelain build-up on refractory dies.

Figure 19

Feldspathic veneers on refractory dies.

Figure 20

Feldspathic veneers on solid cast; frontal view.

Retention of treatment outcomes is considered to be one of the challenges in orthodontics. As the data available in the literature suggests crowding of the anterior teeth after orthodontic treatment is very likely to happen with or without extraction of the third molars.4 In addition, relapse of the extrusive movement of the maxillary anterior teeth is also a concern in this case. To reduce the chance of undesirable changes, a fixed wire retainer was bonded to the lingual surfaces of the anterior teeth. The maxillary central and lateral incisors in this case were extruded significantly more than the canine teeth and by joining the four incisors with the canines using the wire retainer should improve stability.

For many cases, involving the orthodontist can greatly improve the final outcome.

Figure 21

Feldspathic veneers on solid cast; right view.

Figure 22

Feldspathic veneers on solid cast; left view.

Figure 23

Feldspathic veneers.

Figure 24

11 feldspathic veneer.

Figure 25

Feldspathic veneers after cementation.

Figure 26

Intraoral left view.

Figure 27

Intraoral right view.

Figure 28

Close view of final smile.

Figure 29.

Final smile.

The orthodontist can assist in positioning the teeth for conservative prosthetic preparations to preserve as much tooth structure as possible. If a smaller tooth is planned for a full coverage restoration, that tooth can be centered mesio-distally and labio-buccally with a patent overjet. This would minimize the lingual enamel reduction and preserve tooth structure. Similarly, orthodontics can reposition gingiva using a non-surgical approach, setting the stage for subsequent prosthodontic treatment. OH

Oral Health welcomes this original article.

Disclaimer: We would like to thank the patient for trusting us for his treatment and Yuzo Matsumura, RDT, from Elephant Dental Studio.

References

  1. Sarver DM. The importance of incisor positioning in the esthetic smile: the smile arc. Am J Orthod Dentofacial Orthop. 2001 Aug;120(2):98-111
  2. Sarver DM. Principles of cosmetic dentistry in orthodontics: Part 1. Shape and proportionality of anterior teeth. Am J Orthod Dentofacial Orthop. 2004 Dec;126(6):749-53.
  3. Ackerman JL, Ackerman MB, Brensinger CM, Landis JR. A morphometric analysis of the posed smile. Clin Orthod Res. 1998;1(1):2-11.
  4. Song F, O’Meara S, Wilson P, Golder S, Kleijnen J. The effectiveness and cost-effectiveness of prophylactic removal of wisdom teeth. Health Technol Assess. 2000;4(15):1-55

Dr. Goth Siu completed his Doctor of Dental Medicine degree at the University of Pennsylvania in Philadelphia. He then completed a specialty residency program in Prosthodontics at the University of Illinois at Chicago. Dr. Siu is board certified in Prosthodontics in Canada and the US. He is practicing at Dr. Mark Lin Prosthodontic Centre, Markham Dental Group and Profiles Dental Specialists.

 

 

Dr. Nima Mir completed his Doctorate of Dental Surgery (D.D.S.) degree at the University of Southern California (USC) and received his Certificate in Orthodontics and Master of Science (M.Sc.) in Oral Biology at the University of Nebraska Medical Center (UNMC). Dr Mir practices at York Orthodontics in Thornhill.