Written by Richard D. Trushkowsky DDS, FAGD, FADM, FICD Saturday, 31 January 2004 19:00
Extensive dental rehabilitation may involve (1) an interdisciplinary approach, (2) a thorough understanding of the principles of restorative dentistry, (3) appropriate use of new materials and techniques, (4) biologic and aesthetic considerations, and (5) close coordination with a laboratory technician. Prior to treatment planning, the following procedures should be taken: a history; an oral examination; a dental, periodontal, and occlusal analysis; radiographs; photographs; and mounted diagnostic models.1 The primary objective of restorative dentistry is to restore the dentition to health and function. In addition, the aesthetic component has also become extremely important.2
This article presents a case report demonstrating the aesthetic results that can be achieved with an interdisciplinary approach.
|Figure 1. Anterior view demonstrates the deep overbite and degree of destruction.||Figure 2. Right lateral view further illustrates the amount of damage.|
The patient, a 60-year-old female, was referred by an oral surgeon for prosthetic consultation on rehabilitation of a decimated dentition with implants (Figures 1 and 2). Periapical x-rays were taken to supplement the panorex provided by the oral surgeon. Diagnostic models, photographs, and intraoral exam were accomplished. The examination indicated that teeth Nos. 6 through 8 required root canal treatment and teeth Nos. 11, 14, and 21 required extractions. The oral surgeon extracted the teeth and placed freeze-dried bone in the sockets to maintain the ridge. Teeth Nos. 12, 13, 18, 19, 20, 28, 29, and 30 were missing.
The patient's immediate need was to restore her smile for the upcoming wedding of her daughter in 2 months. After consultation with the patient and oral surgeon, it was decided to perform endodontic treatment on teeth Nos. 6 through 8. Following endodontic treatment, teeth Nos. 6 though 10 and No. 14 were to have individual ceramo-metal crowns, and teeth Nos. 11 through 13, 19 through 21, and 28 through 30 were to have implant-supported ceramo-metal fixed bridges.
|Figure 3. Coronally positioned flap reveals fenestration at apex of the upper right lateral incisor and osseous recontouring to achieve an adequate ferrule effect.|
Endodontic treatment was performed on teeth Nos. 6 through 8, then crown-lengthening was accomplished to create an adequate ferrule effect of 1.5 to 2 mm. In addition, there was a disparity in the gingival height of the anterior teeth that would have detracted from the final result. A full-thickness flap was elevated on the labial aspect. Osseous recontouring was accomplished as needed to establish the gingival level of the canines and central incisors apical to that of the lateral incisors. Elevation of the flap revealed a fenestration at the apex of the maxillary right lateral incisor (Figure 3). The apical defect was curetted, but no portion of the root was removed since this would have resulted in poor crown-to-root ratio. The lateral borders of the flap were tacked into position apically. Interproximal interrupted or sling sutures can be used to position the central segment of the flap.
|Figure 4. A photograph of the patient at a younger age aided the design of the provisional restoration and the final aesthetic result achieved.||Figure 5. Provisionals inserted prior to wedding.|
After initial healing had taken place (approximately 1 week), posts and cores were placed in teeth Nos. 6 through 8 and provisional restorations fabricated. Teeth Nos. 9, 10, and 14 were additionally prepared and provisional restorations fabricated. These restorations were adjusted and refined by the addition and removal of acrylic until proper length and position could be determined. An old photograph of the patient helped determine the length of her anterior teeth (Figure 4). Phonetics, aesthetics (with proper lip support), occlusal vertical dimension, and canine guidance were confirmed. This provisional (Figure 5) served as a blueprint for the final definitive restoration.
|Figure 6. Bite registration taken with cotton-tipped applicator placed parallel to the pupils of the eyes aids in laboratory orientation.|
A silicon putty index was made of the relationship between the maxillary anterior and mandibular teeth. A cotton-tipped applicator was placed into the index so that it paralleled the pupils of the eyes in order to provide the laboratory with as much information as possible (Figure 6). A wire-reinforced acrylic provisional bridge extending from teeth Nos. 6 through 14 was fabricated by the laboratory (BioTemps, Glidewell). A diagnostic wax-up of the mandibular posterior teeth and a duplicate of the maxillary provisional were used to create surgical templates for the oral surgeon.
|Figure 7. Impression coping components and laboratory analog.|
|Figure 8. Impression copings in maxillary arch and prepared natural teeth.|
|Figure 9. Impression copings in mandibular arch. Complete seating is verified with radiographs.|
After the wedding, 6 Branemark implants were placed by the oral surgeon; 2 in the maxilla replaced teeth Nos. 11 through 13, and 2 were placed bilaterally in the mandible, replacing the posterior teeth. The distal abutments were wide-body implants. Six months later, the implants were uncovered and osseointegration verified. Implant impression copings were placed in the 6 implants and screwed into position (Figures 7 through 9). Complete seating was verified by x-ray analysis.
|Figure 10. Custom abutments are fabricated for all implant sites.|
Impressions can be taken using either a closed or open tray. A closed tray was used in this case. The impressions were removed, and the impression copings were unscrewed from the implants and seated back into the impression with attached implant analogs. The impression was then poured by the laboratory and a soft-tissue model fabricated (Figure 10). When an open tray is used, the tray is cut so that the impression copings protrude through the impression and can be unscrewed from the implant. The screw heads should be blocked with wax to allow complete seating back into the impression when it is removed. The impression copings remain in the impression upon removal, and implant analogs are placed prior to pouring the model.
|Figure 11. Three provisional bridges were fabricated to restore the implants and evaluate the occlusion.||Figure 12. Ten cast copings are tried in and verified for marginal accuracy.|
The laboratory fabricated custom abutments, cast copings, and provisional bridges (Figure 11). The abutments were tried in, and after complete seating was verified, they were torqued into position; 32 ncm was used for the regular abutments and 45 ncm for the wide-diameter abutments. The cast copings were tried in and fit was verified (Figure 12). Occlusal records were confirmed so that the laboratory could mount the models in their correct relationship. The provisional bridges were inserted on teeth Nos. 11 through 13 (after removing this segment of the previous provisional), teeth Nos. 19 through 21, and teeth Nos. 28 through 30. The laboratory fabricated individual ceramo-metal crowns on teeth Nos. 6 through 10 and 14 and 3-unit bridges for teeth Nos. 11 through 13, 19 through 21, and 28 through 30. IPS d.Sign (Ivoclar Vivadent) porcelain was used for all the restorations.
|Figure 13. Right lateral view in occlusion|
|Figure 14. Anterior view of finished restoration demonstrates correct height of gingiva.|
|Figure 15. Left lateral view in occlusion.|
|Figure 16. Occlusal view of maxillary finished restorations and old bridge on tooth Nos. 3 through 5.|
|Figure 17. Occlusal view of completed mandibular restorations.|
|Figure 18. Final result achieved as the outcome of interdisciplinary dentistry.|
The final result demonstrated aesthetics, proper vertical dimension, lip support, and proper phonetics (Figures 13 through 18). However, persistent oral hygiene problems with plaque accumulation detracts somewhat from the final result. Additional osseous recontouring at the initial surgery would have created a better biologic width but would have reduced the crown-to-root ratio. Splinting the teeth would have mitigated this effect but made it more difficult to maintain gingival health.
The vertical dimension of occlusion is the vertical position of the mandible relative to the maxilla with the maxillary and mandibular teeth intercuspated at the most closed position. Teeth themselves are not the determinants of the vertical dimension. The vertical dimension of the space available between the fixed maxilla and the muscle-positioned mandible will determine the position of the teeth. When the patient has lost natural occlusal stops for determining vertical, the closest speaking technique provides a reliable technique for determining the vertical dimension of the occlusion. If the determination of vertical is made on a patient who has lost natural vertical dimension, missing teeth must first be replaced with a provisional restoration or fabricated bases. Facial assessment of vertical relation provides a starting point in evaluating vertical dimension.
After proper lip support with a normal vermilion border at vertical relation of occlusion has been achieved, confirmation of occlusal vertical dimension can be achieved by the phonetic method. The patient is seated in an upright position with the occlusal plane parallel to the floor. The patient is asked to close in centric occlusion, and a line is drawn on the mandibular anterior teeth at the level of the maxillary incisal edge. This is the centric occlusion line. The patient is then asked to make an s sound, and a line is drawn again on the mandibular anterior teeth. This is called the closest speaking line. The space between the 2 lines is the closest speaking space.
Have the patient wet his or her lips, open the mouth and then have the lips lightly touch. The patient should practice this several times. This is the point where the mandible should be near its vertical dimension, and a slight space should exist between the teeth (freeway space or interocclusal distance). The lips are parted, and the space between the teeth is measured with a caliper or Boley gauge. This will help determine the difference between the rest vertical position and the occlusal vertical dimension. This information can be transferred to study models that have been mounted in centric occlusion. Orthodontic wax or composite can be added to the incisal edge of the anterior teeth and provide support for the upper lip. Adequate freeway space must be maintained.3,4
RESTORATION OF ANTERIOR TEETH
Proper restoration of maxillary anterior teeth is predicated upon precise position of the incisal edge, correct lingual contour of each tooth, and the labial contour of each tooth. There are several factors that combine to determine these factors. These determining factors are maxilla-to-mandible relationship at centric relation, lip support, lip closure path, tooth-to-lip relationship during formation of f and v sounds, envelope of function, tooth-
to-tooth relationship during the s sound, and neutral zone. After the shape of the mandibular incisor is finalized, the lingual contour of the maxillary anterior teeth can be determined at the correct vertical dimension previously determined.
The labial contour of the maxillary anterior teeth should support the upper lip at rest. The apical portion of the labial contour relates to the labial contour of the alveolus. The incisal one third should be contoured to permit the lips to come together without interference from the teeth. The incisal edge position can be determined by using functional relationships necessary during the f and v sounds and in conjunction with the smile line to help determine the position of the incisal edge and horizontal position of the teeth. The maxillary incisal edge should preferably follow the curve of the lower lip. The relationship should be ascertained during provisional fabrication.
The lingual contour of the maxillary anterior teeth should be determined. The lingual contour from centric relation out to the incisal edge in all excursions is the anterior guidance. If the maxillary lingual surfaces are too far to the lingual, too steep, or not concave enough, excessive wear, hyper-mobility, or development of spaces may result. The cingulum contour can be analyzed as to its correctness using phonetic relationships during t and d sounds; s sounds can be used to verify maxillary anterior teeth contour. Too much space causes a lisp; too little space causes the teeth to "bump." These procedures will result in maxillary anterior teeth in their correct neutral zone.3,4
DIAGNOSIS AND TREATMENT PLANNING OF GINGIVAL ASYMMETRY 5-9
Symmetry between maxillary central incisors is important but minor asymmetries are a frequent occurrence. Maxillary lateral incisors vary more in shape than the central incisors and frequently are asymmetrical. Maxillary canines are not usually aligned on the same horizontal level. A ruler can be held parallel to the interpupillary line in order to ascertain any gingival asymmetry. Gingival asymmetry can be treated with orthodontic eruption or intrusion. The average location of the gingiva in class I demonstrates a symmetric level of the central incisors; lateral incisors are located lower, and the canines are at the same level as the centrals. If the asymmetry is corrected surgically, evaluation would have to be made of adequate bone support. The decision between gingivectomy flap surgery and osseous recontouring or orthodontic extrusion is made according to how much attached gingiva is available, the location of the cemento-enamel junction, and the final location of the incisal edge. For balance, the incisal edge and the posterior plane should be analyzed as well as gingival levels.
The length of the maxillary anterior teeth is determined by measuring the distance from the incisal edge to the gingival margin. The anatomic crown length is determined by measuring the distance from the incisal edge to the cementoenamel junction. Once the desired length and final edge position of the anterior teeth are determined, the amount of osseous recontouring required could be ascertained.
The gingival tissues must be evaluated. The height of the gingiva is determined by measuring the distance from the gingival margin to the mucogingival junction. The difference between this and the measurement of the amount of soft tissue that needs to be removed will determine the amount of gingiva left after the surgical procedure. The alveolar crest can be determined prior to surgery by sounding the bone under anesthesia. The alveolar crest should be 2 mm apical to the CEJ. The CEJ can be felt by tilting the probe against the tooth and feeling where the crown meets the root surface. The final result will expose minimal gingiva with the gingival contour symmetric, and the teeth should be at normal length.
A gingivectomy or gingivoplasty with an internal or external excision is indicated where 3 to 5 mm of gingiva would remain after surgery and where no osseous recontouring is required. A collar of gingiva is removed from the mesial line angle to the distal line angle of each tooth. The papilla area is not involved. The height of contour should be distal to the midline rather than semilunar in form. This wedge of tissue can then be removed. The height of bone at this time should be 2 mm subgingival. Otherwise osseous reduction is required.
Crown-lengthening is performed by reflecting a mucoperiosteal flap and removing bone (osteotomy), followed by recontouring of the alveolar process (osteoplasty). Flaps are repositioned apically and sutured into place. The "biologic width"—the distance between the alveolar crest and the margin of the crown preparation—should be maintained at 3 mm. The interdental papilla should be handled in a manner to prevent loss of height and exposure of the interdental space. Only a thin final portion of the interdental papilla should be reflected with the scalloped facial flap. All interdental tissue within the proximal line angles should be maintained. A palatal flap is not necessary if only performed for aesthetics. Leaving the interdental papilla in place will avoid the formation of an unaesthetic black triangle.
IMPLANT POSITIONING 10-17
Implant fixtures should be placed in the most advantageous position, depending on the bone available and anatomic structures present. Fixtures should not be placed too far lingually or palatally since this may interfere with speech. Implants should also be placed so that screw access holes (screw-retained fixtures) do not emanate from the buccal or labial. The most coronal extension of a crown-abutment location should be 0.5 to 3 mm subgingival. This should coincide approximately with the CEJ of adjacent teeth and usually 4 mm or more apical to the CEJ of adjacent cervical-enamel junctions. This allows the chosen veneering material to be applied to the casting in such a way that the cross section of the final restoration will closely resemble that of the natural tooth.
When placing fixtures, the ideal location for fixture placement should be determined prior to surgery. If teeth are missing, a denture or diagnostic wax-up is needed. A surgical template acts as an aid to the oral surgeon in indicating desired positioning. Vertical or horizontal radiopaque markers can be processed in the template and utilized during radiographic analysis. The design of the template will depend on individual circumstances and the diagnostic and surgical needs.
Implant placement depends on available bone, anatomic structures, aesthetic considerations, and minimizing transverse forces on the implant and bending moments. If a force acts on an implant in a transverse direction relative to the implant axis, it will create a bending moment on the implant. Bending only a small portion of the cross section of the implant counteracts the load. This creates a greater load at the terminal portion of the fixture and greater stress in the implant and the surrounding bone.
In placing implants into the edentulous spaces in partially dentate jaws, implants are often placed in a linear configuration. This eliminates the compensatory effect of an offset implant. The straighter the alignment, the greater the bending moment. Occlusion is an important factor in load distribution. Occlusal contacts should be centered, thereby reducing the lever arm. Lateral excursive movements should possibly be eliminated. High cusp inclinations will lead to higher transverse forces. Because of high stress, fixtures with a diameter of 4 mm are recommended for molar replacement.
CHOICE OF RESTORATIVE MATERIAL
IPS d.Sign has a unique combination of fluorapatite and leucite crystals that imitate the optical properties of natural teeth by dispersing light in a manner similar to the natural dentition. A high degree of light refraction and reflection are created by the crystals without the use of opaque materials. The crystals also scatter light so that a considerable translucency can be achieved. The opaque dentin is called deep dentin. They are dentinal opaquers rather than opaque dentin, thus providing excellent results in thin layers. The wear and the antagonist enamel wear seem to be low.18 This is a highly desired attribute in a ceramic material along with its aesthetic potential.
Comprehensive treatment planning may involve a variety of specialties. Sometimes the procedures are delegated to several individuals. However, the restorative dentist has to envision the outcome and be able to coordinate properly all the needed procedures. There has to be a viable interchange of information. The case presented illustrates the delicate "ballet" that must exist to achieve an aesthetic, biologic, and functional rehabilitation.
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The author wishes to thank Dr. Allan Klein (Staten Island, NY) for the placement of the implants, and Adrian Jurim, MDT (Jurim Dental Studio, Great Neck, NY) for the excellent laboratory work.
Dr. Trushkowsky maintains a private practice in Staten Island, NY, emphasizing aesthetic and restorative dentistry. He is a fellow in the Academy of General Dentistry, the Pierre Fauchard Academy, Academy of Dental Materials, and the American and International College of Dentists. He is a member of the American Prosthodontic Society, the Academy of Osseointegration, and the American Academy of Cosmetic Dentistry. He has authored more than 60 articles on aesthetics and dental materials, has spoken nationally and internationally at many major dental meetings, and is online with Dental Quest. He is on the editorial board of Contemporary Esthetics and Restorative Practice, is an evaluator for many leading manufacturers and CRA, and is a senior consultant to the Dental Advisor.
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