Implementing a Systematic Digital Workflow

INTRODUCTION
With greater public awareness of the possibilities of today’s cosmetic dental reconstructions, dentists and their laboratory teams are often challenged to meet the high aesthetic and functional expectations of increasingly demanding patients. Now, more than ever, it behooves doctors and dental technicians to work together as part of an interdisciplinary and collaborative team to coordinate treatments, select the ideal restorative materials, and to plan cases.1,2

Fortunately, there are now a number of digital-based technologies that can be incorporated into the requisite thorough diagnostic and treatment planning processes,3 as well as used for fabricating various components of treatments. When used in combination with a systematic and collaborative plan for preparing and executing a treatment plan, these tools can help dentists achieve aesthetic and functional success when full-mouth reconstructions are required.

Simultaneously, advances in technology and material science have provided dentists and lab teams with restorative, high-strength, all-ceramic options that no longer need to be veneered and can be cost effective and aesthetic alternatives for full-mouth rehabilitations.4,5 In fact, CAD/CAM is making it possible for dentists, in collaboration with their lab teams, to deliver monolithic zirconia restorations with individual characterizations that demonstrate high flexural strength and excellent long-term properties.6-8

CASE REPORT
Diagnosis and Treatment Planning

A woman in her mid-60s was referred to the practice by her current dental provider because she was dissatisfied with the appearance of her smile (Figure 1). She commented that she felt her existing teeth were too dark, spaced out, and flared facially, contributing to an aged appearance and, more importantly, she suffered from sensitivity to cold, tension headaches, grinding, and a limited range of function. Initial diagnostic evaluation during the first appointment consisted of a series of digital images with study casts, a centric relation bite record, a face-bow transfer, a computed tomography (CT) scan, and a full-mouth series of digital radiographs.

Figure 1. Retracted preoperative view. Figure 2. Pre-op maxillary occlusal view.
Figure 3. Pre-op mandibular occlusal view. Figure 4. View of the 3-D White Wax-Up (Arrowhead Dental Laboratory).
Figure 5. View of the 3DDX Surgical Guide (3D Diagnostix) in place. Figure 6. View of the selected dental implant (Engage [OCO Biomedical]).

Examination revealed several maxillary teeth that had worn composite restorations, cracked or leaking amalgam restorations, recurrent decay at the margins of existing crown restorations, and abfractions with cervical decay (Figure 2). Tooth No. 12 had a periapical lesion due to a failing root canal and periodontal disease with Class II mobility. Existing crown restorations on teeth Nos. 20 and 28 had recurrent decay on the facial aspects, where there was quite a bit of recession (Figure 3). Teeth Nos. 21 and 29 had large amalgam restorations with deteriorating margins, as well as cracks present.

After reviewing the clinical findings and mounted models, the patient was diagnosed with a restricted envelope of function and decreased occlusal vertical dimension (OVD) from continuous wear.9 To develop a treatment plan and determine if the OVD could be increased, a diagnostic 3-D White Wax-Up (Arrowhead Dental Laboratory) was fabricated (Figure 4), along with a preparation guide and a template for the fabrication of provisional restorations.

Based on information gathered from the initial consultation and digital images, it was determined that the maxillary central incisors could be lengthened by 1.2 mm to improve the aesthetics, and the canines would also be lengthened to restore guidance in lateral excursions. Overall, OVD would be increased by 1.5 mm.10 The goal in the lower arch was to create an ideal arch form where the anterior teeth were not so flared and worn.11 It was further determined from the diagnostic wax-up that aesthetics and function could be enhanced by restoring the remaining dentition. Since tooth No. 12 required an extraction, replacement options were discussed with the patient.

A thorough evaluation of the remaining bone in the edentulous spaces was performed by examining the 3-D conversions of the CT scan (ie, CoDiagnostix [3D Diagnostix; 3ddx.com]).12,13 By examining the cross-sectional views, it was determined that the patient would require block grafts in the mandibular posterior regions of teeth Nos. 18 and 19, as well as Nos. 30 and 31, to enable implant placement due to height and width deficiencies in these areas.12 In the maxillary arch, placing implants in the molar regions would require sinus augmentation.13 However, implants could be placed in the Nos. 4 and 13 positions without any major bone grafting procedures.

After analyzing all available information, the doctor, along with the patient, decided that the final treatment would consist of splinted monolithic zirconia crown restorations (Wieland Zenostar [Ivoclar Vivadent]) from Nos. 5 to 12, with No. 12 being a distal-cantilever pontic. In the areas of teeth Nos. 4 and 13, implants would be placed, followed by their corresponding custom abutments and crown restorations. In the lower arch, the teeth would be segmentally connected with splinted crowns—premolars, separate canines, and then incisors.

Per the manufacturer, the selected zirconia material combines excellent flexural strength with the aesthetics of natural tooth shades.4-8 In this case, the patient desired a 040 bleach shade (Chromoscope [Ivoclar Vivadent]). Wieland Zenostar is especially suitable for making monolithic restorations but can also be used as an aesthetic framework material for a layered technique.

Surgical Preparation
A tooth-supported surgical guide (3DDX Surgical Guide [3D Diagnostix]) was inserted and placed on the existing maxillary teeth, with the sleeves in the areas receiving implants for teeth Nos. 4 and 13 (Figure 5).14 Using the surgical handpiece (Mont Blanc) and surgical motor (AEU-7000 [Aseptico]) at 1,400 rpm with copious amounts of chilled sterile saline, the implant sites were initiated with a 1.95-mm long stop pilot drill.

Once the osteotomies were complete and further irrigated with sterile saline, an implant driver was used to initially place the implants (Engage [OCO Biomedical]) (Figure 6). The ratchet wrench was then connected to the adapter to further drive the implant into the osteotomy until the implants were torqued to their final depths, reaching a level of about 50 to 60 Ncm. Using resonance frequency analysis, an implant stability quotient (ISQ) value was recorded using the Osstell implant stability meter (Osstell) verifying adequate implant fixation.

Tooth No. 12, which exhibited a vertical fracture and was no longer restorable, was atraumatically extracted (Physics Forceps [Golden Dental Solutions]). The socket was grafted with a putty blend of cortical mineralized and demineralized bone grafting material (Maxxeus) followed by a pericardium membrane (Maxxeus).15 Primary closure was achieved by suturing the tissue with 3.0 mm black silk sutures (Blue Sky Bio).

After surgery, the remaining teeth were prepared for crown restorations. Any old amalgam restorations or indications of recurrent decay were removed with a carbide bur (Midwest MultiPrep Premium Carbide Burs [Dentsply Sirona]) and cored using MultiCore material (Ivoclar Vivadent). Any endodontic therapy was accomplished with rotary files (TF Adaptive [Kerr Endodontics]).

Figure 7. Maxillary final impression (Take 1 Advanced [Kerr]) taken using a heat-moldable customizable PMMA impression tray (Instant Custom C&B Trays [Goodfit]). Figure 8. Mandibular final impression (Take 1 Advanced).
Figure 9. A full-mouth bite relations jig was taken. Figure 10. View of the provisional restorations after placement.
Figure 11. The maxillary restorations were cemented using a dual-cure adhesive resin cement (Multilink Automix [Ivoclar Vivadent]). Figure 12. View of the maxillary and mandibular restorations (Wieland Zenostar [Ivoclar Vivadent]) after delivery.

Tooth preparations were carried out using a clear reduction guide (the Arrowhead Dental Laboratory team had previously provided it with the 3-D White Wax-Up) to ensure adequate reduction for the definitive zirconia crown restorations. Full-arch impressions were taken using custom fitted crown and bridge trays (Instant Custom C&B Trays [Goodfit]). Made of a proprietary polymethyl methacrylate (PMMA) material that becomes adjustable when heated in boiling water, these trays provided a quick and efficient way of capturing a dimensionally accurate impression with uniform thickness of impression material. Once molded and customized to the patient’s maxilla and mandible, full-arch impressions were taken (Figures 7 and 8) using a heavy and light vinyl polysiloxane impression material (Take 1 Advanced [Kerr]).

A bite relations jig fabricated on the 3-D White Wax-Up models was then tried in the mouth. Light-body impression material was placed into the relations jig and seated into the patient’s mouth and onto the prepared teeth (Figure 9). The patient was asked to bite into the relations jig until she reached the vertical stops, then time was allowed for the material to fully set.

Provisionalization
A provisional restoration, which would aid in determining the best size, shape, color, and position for the definitive restorations, was made using a matrix impression (Sil-Tech [Ivoclar Vivadent]) of the 3-D White Wax-Up. Using a bleach shade of temporary material (Structur 3 [VOCO]), the matrix was quickly filled and placed on the patient’s prepared teeth. Within minutes, the provisionals were fabricated and easily trimmed with appropriate burs and discs (Kerr Rotary). A desensitizer (Systemp Desensitizer [Ivoclar Vivadent]) was applied to the teeth and dried, and the provisionals were temporarily cemented (TempBond Clear [Kerr]) (Figure 10). The patient was instructed about their care and use proper use.

A few weeks later, the patient returned for evaluation of aesthetics, phonetics, and bite. At that point, she had already expressed excitement and confidence with her provisional restorations, commenting that many of her friends noticed that she looked younger. Since no adjustment or modification to the temporaries was needed, the dental lab team was instructed to replicate the 3-D White Wax-Up when fabricating the definitive restorations.

Figure 13. The implants were ready for impressions. Figure 14. The abutment delivery jigs were placed.
Figure 15. The abutments were torqued. Figure 16. Retracted post-op view of the completed case.

Laboratory Communication
The 3-D White Wax-Up, color photographs, impressions, and bite relations were forwarded to the lab, where a scan of the 3-D White Wax-Up was used to select an appropriate arch form, tooth size, and occlusion. Once digitally designed, virtual images of the proposed reconstruction were forwarded through 3Shape Communicate (3Shape) to the treating doctor’s email. Any minor adjustments in tooth shape and contour were communicated to the dental technician to achieve the most ideal aesthetics.

Cementation
The patient returned 3 weeks after the postoperative appointment for removal of her provisionals and the placement of the definitive restorations. Once the patient was appropriately anesthetized, the provisional restorations were removed using a pneumatic crown remover (DentCorp). Any remaining temporary cement was removed, and the teeth further cleaned with a solution containing 2% chlorhexidine (Consepsis [Ultradent Products]). Individual as well as splinted crown restorations, which had been lab-fabricated using the Wieland Zenostar zirconia, were tried in to verify an accurate fit. Radiographs were taken to further verify complete seating of these restorations. Once confirmed, the patient was given the opportunity to view her smile. She was very pleased with the appearance of these restorations, so the cementation steps were initiated. After try-in, the restorations were cleaned prior to the cementation steps using a universal cleaning paste (Ivoclean [Ivoclar Vivadent]). This cleaning gel is simply applied to the intaglio surfaces of the restorations, left in place for 20 seconds, and then thoroughly rinsed off using air-water spray. The splinted crown restorations were seated utilizing a white shade of a dual-cure adhesive resin cement (Multilink Automix [Ivoclar Vivadent]) (Figure 11), and the restorations secured until final polymerization was achieved. Per the manufacturer, some of the advantages of this cement include excellent shade stability, lifelike fluorescence, easy cleanup, and excellent radiopacity.

Finally, after cleanup of any excess cement, the occlusion was checked, adjusted as needed, and verified using a T-Scan (Tekscan) to ensure all proper contact points were in their ideal positions to optimize the function and longevity of the reconstruction (Figure 12).

Four months later, the healing caps were removed from the implants in the Nos. 4 and 13 areas (Figure 13). Using the Osstell meter, osseointegration was further confirmed and impressions taken for custom abutment and crown fabrication. Two weeks thereafter, the custom abutments were placed and torqued (per manufacturer’s instructions) (Figures 14 and 15), and radiographs were taken to confirm full seating of both abutments. Once confirmed, the crown restorations were seated to complete the case (Figure 16).

The patient was very pleased with her improved and whiter smile, and she was pleased to be able to receive all the necessary treatment procedures under one roof. Additionally, she commented on how effectively and efficiently the practice treatment team worked together to deliver her new dental restorations.

CLOSING COMMENTS
There is an increasing need on the part of the public to be able to find dentists who can deliver quality aesthetic and functional restorations in a timely and consistent manner. By using virtual mockups, CBCT technology, guided surgery, and CAD/CAM restorations, clinicians can further enhance treatment options as well as provide comprehensive treatment within their practices. With a technology-driven and digitally supported collaborative relationship with the laboratory team, outcomes can be routinely predictable, aesthetic, and functional.

Acknowledgment
The author thanks Chris Barnes and the team at Arrowhead Dental Laboratory (Sandy, Utah) for fabricating the restorations presented.


References

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Dr. Nazarian maintains a private practice in Troy, Mich, with an emphasis on comprehensive and restorative care. He is the director of the Ascend Dental Academy and is a Diplomate in the International Congress of Oral Implantologists. He is widely published and has conducted lectures and hands-on workshops internationally on aesthetic materials and dental implants. He can be reached at (248) 457-0500 or at aranazariandds.com.

Disclosure: Dr. Nazarian reports no disclosures.

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