One-Stage Surgical Crown Lengthening and Provisional Prosthetic Placement: An Interdisciplinary Approach

Clinical crown lengthening is usually a very useful surgical resource for achieving surprising aesthetic and functional solutions in dental practice.¹ The typical procedure comprises exposure of the teeth or root remnants, followed in a second step by prosthetic replacement. In some cases the surgical intervention is preceded by orthodontic extrusion to favor the availability of abundant bone and gingival tissue. Thanks to this versatile surgical technique, endodontic treatments can be applied to fractured teeth or root remnants overlying a healthy dental structure,² and preceding actual aesthetic prosthetic restoration. From the functional perspective, clinical crown lengthening procedures offer highly predictable and stable results, since they are based upon manipulation of the bone and gingival margin, ensuring an adequate spatial relationship based on a functional constant, the biological width^.3,4
In some cases, such as the case presented in this article, performance of the surgical and prosthetic steps in 2 different sessions may prove inadequate in terms of patient satisfaction and appearance. Both coronal and radicular portions may be exposed cervical to the prosthetic margin of the individual crowns (short in this case) or pre-existing bridge, yielding an unattractive appearance in patients with ample dental display or gummy smile. Under such circumstances it is preferable to plan a single intervention comprising both the surgical step and placement of a provisional prosthetic restoration.
This approach clearly requires planning, organization, and discipline, with the establishment of a coordinated and efficient team comprising the periodontist, rehabilitating dentist, prosthetic laboratory technician, and the patient.

CLINICAL CASE

Figure 1a. Initial condition. Excess gingival tissue and short prosthetic crowns, accompanied by the presence of a central diastema.	Figure 1b. View of the final result. Reconstruction with complete individual Procera (zirconium) crowns.
Figure 2a. Initial x-ray view.	Figure 2b. Postoperative x-ray view.

A 57-year-old woman presented with dental aesthetic problems. The clinical and radiological examinations of the upper anterior sector revealed the presence of short crowns that exacerbated the appearance of a gummy smile (Figure 1a). The central incisors presented with a diastema, together with short, rather square crowns. Figure 1b shows the final outcome of individual crown placement (Procera [Nobel Biocare]) from canine to canine, however treatment extended from the right first premolar to the left second premolar.
The rest of the evaluation revealed the absence of the upper right second premolar and upper molars—thus depriving the patient of posterior dental support. The clinical condition was accompanied by right lower first molar furcation impairment, while the upper jaw showed marked bone atrophy, resulting in proximity of the maxillary sinuses (exhibiting enhanced pneumatization; Figure 2a). The panoramic radiograph in Figure 2b shows final patient rehabilitation. In addition to the crowns of the upper teeth, she received 4 endosteal implants (Replace Select, 4.3 mm [Nobel Biocare]) with bilateral sinus lifts in the upper arch—since at least 4 mm of bone from sinus floor to alveolar margin was available. The lower arch was likewise rehabilitated with individual Procera crowns, including premolarization of the right first molar, which was hemisectioned to control the type III furcation affecting it. The rest of periodontal treatment included control and treatment of chronic periodontitis and clinical lengthening of the lower anterior teeth. The patient was instructed on the wearing of a night guard following treatment.

Figure 3a. Surgical splint in position.	Figure 3b. The incisions show the new cervical limit of the gingival margin—the rest of the procedure being completed manually. The incision must be designed with a degree of inclination to achieve a thin flap margin in order to facilitate its posterior adaptation.

Figure 3c. After again positioning the surgical stent (not shown), ostectomy and osteoplasty are performed to prepare the new bone margin, which should be 3 to 4 mm from the cervical margin of the splint.

Figure 3a shows a surgical stent with the desired dento-gingival aesthetic modifications reflecting the changes required in this particular clinical case. Construction of the stent always requires prior assembly and waxing in a semiadjustable articulator (Panadent PCH [Panadent]), followed by an imprint and the preparation of a plaster model on which the surgical guide is then constructed. The dental dimensions are defined, fixing the incisal margin, occlusal plane, and possible gingival margin both at rest and at maximum smile, considering the linear measures in width and height as well as the proportionality between the latter to ensure a natural effect.5,6 In this context, the ideal height from incisal margin to gingival margin was accepted to be between 10.5 and 11.0 mm. With the purpose of transferring the information to the articulator, a facial arch was taken parallel to the horizon, in order to transfer the incisal plane and inclination.
Waxing can be made according to the aesthetic and functional needs of the patient. Under these conditions the acrylic surgical stent was prepared, which allowed us to conduct objective and subjective clinical evaluations preoperatively, thereby affording reliable prediction of the final outcome, and even consider the subjective assessment of the patient and relatives.
Figure 3b shows initiation of the surgical procedure. Of note is the inclination of the scalpel blade, since a rather thin flap is required for both dental adaptation at the end of the procedure and for achieving an intimate appositioning to the bone. The incisions show the new cervical limit of the gingival margin. After marking the gingival contour and locating concrete details such as the dental zenith, the splint was removed and instrumentation was continued manually. In cases such as this, with the presence of exostosis, it is advisable to define sectioning, placing the margin 1 to 1.5 mm apical to the desired point. By eliminating the bone prominences the flap is projected toward a more incisal position, and this must be compensated for in advance.
The decision to either eliminate gingival tissue or apically position a flap depends on the remaining keratinized tissue (attached gum). In our patient sufficient tissue remained. The interdental papillary component was not modified in order to predict the papillary filling in the restorations to be manufactured.⁷ The buccal flap was raised, taking care to preserve the full buccal papillary thickness and adjust it posteriorly to ensure a uniform and thin thickness, using a rough, oval-shaped diamond drill. Next, and again with the help of the surgical stent, a new bone margin was defined, located at least 3 mm apical to the recently redefined gingival margin (Figure 3c). The contour and zenith designed in the soft tissue were then accurately reproduced at the alveolar bone. In this case maxillary osteoplasty was required due to the presence of bone prominences and the lack of inter-radicular festooning. The papillary contents and interproximal bone were not modified, for as has already been noted, their preservation was necessary for predictability in papillary filling and fixation of the apical extreme of the contact area.

Figure 4a. General view of the complete provisional bridge, cemented before flap suturing.	Figure 4b. Details of the prosthetic adaptation and cementing, together with the ostectomy design for redefining the new space for the biological width.

This is the point of intervention of the rehabilitating dentist, who in this case removed the existing bridge and conducted repreparation from the upper right first premolar to left second premolar. Figures 4a and 4b show the cervical adaptation process. In this case construction of the provisional restoration was indirect, based on the data afforded by the diagnostic assembly prepared before surgical management. In relation to the provisional bridge, special care was taken to ensure harmony with the new established contour and marginal anatomy. An adequate cervical emergence profile was carefully defined with reproduction of the cervical convexity of the crown. This serves to support and guide tissue positioning, there-by making gingival tissue shape and position more predictable postoperatively.
It should be noted that the location of the prosthetic margin with respect to the bone margin is adequate for redefining a new biological thickness, under surgical control. This in turn may be expected to induce healing, regeneration, and structural stability of the periodontal tissues in their new position. The bridge was adjusted and adapted conventionally. Naked eye visualization of the prosthetic termination ensured optimum efficiency. The margins were then finely polished, with bridging from upper right first premolar to left second premolar, and the bridge was retained with temporary cement.

Figure 5a. Immediate postoperative view (surgical and prosthetic).	Figure 5b. Postoperative view (after 3 weeks).
Figure 6a. Procera (zirconium) crowns in the working models prior to cementing.	Figure 6b. Final outcome after 4 months. The tissue stability and compatibility are excellent, as are crown shape and color management.

The prepared flap was then sutured in its new location (Figure 5a) using Ethilon 5-0 mononylon suture (Ethicon). The immediate postoperative care included the application of cold facial bandages and the prescription of anti-inflammatory medication in the form of loxoprofen (Loxonin 60 [Siegfried Rhein]), together with a combination of proteolytic enzymes and streptodornase (Varidasa  [Wyeth, Mexico]) to avoid the formation of edema. Pain was controlled with ketorolac tromethamine (Dolac [Syntex, Mexico]), while antimicrobial control was afforded by 500 mg of amoxicillin administered 3 times a day (Amoxil [GlaxoSmithKline]). This complete protocol was started 2 days before the intervention and was continued for 5 days thereafter. Regarding bacterial plaque control, the patient was prescribed dental brushing with 0.12% chlorhexidine digluconate rinses (Bexident  [Siegfried Rhein]) 3 times a day until 1 week after suture removal. The healing process in turn was facilitated with ascorbic acid (2 g/day of Redoxon Forte [Roche]). Figure 5b shows the results obtained 3 weeks after the intervention. Tissue evolution is seen to be excellent.
Figures 6a and 6b show details of the complete crowns on the model and in the mouth of the patient, cemented with universal cement  (RelyX Unicem Self-Adhesive Universal Resin Cement [3M ESPE]). Of note is the excellent tissue stability and adaptation achieved after 4 months, as well as the management of the form, color, and control of the proportions—including height fixation of proximal contacts for papillary preservation of the fitted crowns.

DISCUSSION

Interdisciplinary work implies not only joint decision making, but in some cases (such as that of our own patient) a need for simultaneous and coordinated work in operative aspects to optimize the duration of treatment and the immediate and final outcome. In this case involving a patient with a gummy smile prosthetic treatment independent of the initial surgical step would have required the patient to display for at least 8 weeks the apparent and unattractive gingival “recession” caused by shortness of the original prosthetic crowns when part of the natural crown appears cervical to the prosthetic margin.
The described simultaneous surgical intervention and prosthetic placement is applicable not only to specific cases such as our own, characterized by the existence of a prior prosthetic component, but also to all cases of upper anterior sector treatment. The placement of a provisional immediate prosthesis accompanying the surgical step has further implications, particularly when a visible zone is implicated and excellent aesthetics and tissue stability are required. When working with a surgically exposed zone, prosthetic preparation or repreparation may be more precise, with better elaborated and supervised adaptation, sealing, and anatomical cervical conformation of the provisional restoration. This in turn influences the long-term outcome in terms of appearance and stability, since controlled and simultaneous manipulation of bone position, gingival margin, and prosthetic form and adaptation is accomplished.

References

Acknowledgments

The authors thank Eladio Gonzalez, technician and owner of Fusión Dental (Mexico), for the laboratory work demonstrated in this article.

Dr. James maintains a private practice limited to prosthodontics and implant dentistry in León, Guanajuato, Mexico. He can be reached at doctor@alejandrojames.com.

Dr. Castellanos maintains a private practice limited to oral medicine and periodontics in León, Guanajuato, Mexico. He can be reached at castellanosjose@hotmail.com.