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Full Mouth Rehabilitation with Lithium Disilicate Crowns and Titanium Abutments

March 1, 2014
by Wilson J. Kwong, DMD


INTRODUCTION
Wear damaged dentition present in patients with a variety of problems, including malocclusion, loss of function, and poor esthetics. A universal occurrence, most clinicians generally identify wear as the combination of erosion, attrition, and abrasion.1 Although wear naturally occurs during aging, it can lead to decreasing the protective network of enamel and dentin, leaving teeth vulnerable.2 Wear can also contribute to compromised esthetics. A decreased enamel thickness exposes dentin, altering tooth color from the white of enamel to the yellow of dentin.1 Decreased enamel thickness also weakens teeth, making them more prone to chips and fractures.

Additionally, wear can affect posterior support and occlusal attrition. Loss of posterior support can lead to decreased clenching force because of the increased loading on the remaining teeth.3 Missing posterior teeth negatively affect the adjacent teeth and can reduce their longevity.4 The loss of posterior support also increases the risk of temporomandibular disorders.5 Similarly, major occlusal attrition changes the relationship of teeth, decreasing function and stability. Attrition can occur from natural tooth-to-tooth contact or from pathological friction (e.g., bruxing); both damage the occlusal surfaces, reducing contact and function.1

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In certain cases, extensive tooth wear requires extractions and placement of mandibular or maxillary dental implants. Clinicians determine the ideal treatment plan with several assessments, including examination of viable hard and soft tissue. Patients with limited alveolar bone require adequate build-up in height and width to ensure functional, biological, and esthetic properties of the proposed restorations.6 Allografts build-up and aid in proper implant healing. An allograft also increases the thickness of the marginal gingiva, which prevents vestibular gingival recession and ensures tissue stability.7

Another necessary assessment prior to implant placement is evaluation of the implant placement angle. As the placement of the implant occurs through the extraction socket, attentiveness to bone location and perimeters of remaining bone ensures that the implant is placed centrally and securely. Risk of an inferior alveolar nerve (IAN) injury remains possible, and identification of the inferior alveolar canal relative to the posterior mandible helps to avoid unpleasant complications.8 An improperly aligned implant can negatively affect the abutment attachment and fit, inhibiting the success and esthetics of the overall restoration.

Once placed, the coating and surface of an implant can provide increased benefits to facilitate osseointegration and future restorative success. Titanium implants with an anodized surface have been shown to provide enhanced osseointegration.9 A porous microtextured surface of an implant also contributes to the osteoconductive properties, which help maintain bone stability during the healing process.10,11 The combination of a porous and titanium oxide coated bone-implant has been shown to exceed the osteoconductive properties of a typical calcium phosphate-coated bone-implant.10

The implant, abutment, and proper healing set the foundation for the final all-ceramic crown restoration. Lithium disilicate is an ideal material for implant-supported and highly esthetic restorations. Needle-like crystals form within lithium disilicate and comprise approximately two thirds of the volume, providing greater strength, durability, and esthetics.12,13 Lithium disilicate posterior crowns also demonstrate increased strength when compared to feldspathic glass ceramic.14

Lithium disilicate is indicated for a variety of treatments, including inlays, onlays, veneers, partial crowns, anterior and posterior crowns, and implant restorations.13 When used for posterior crowns, lithium disilicate demonstrates a monolithic strength unlike any metal or metal-free restorations.13 When used with smile design principles, lithium disilicate achieves natural-looking and durable restorations.15

CASE PRESENTATION
A healthy male patient in his mid-60s presented with significant tooth damage and wear. The patient’s chief complaints were poor esthetics and function, especially while eating. Preoperative photographs of the patient were taken, including a close-up frontal view (Fig. 1), close-up frontal retracted view (Fig. 2), close-up palatal view (Fig. 3), and a close-up mandibular occlusal view (Fig. 4). The patient was assessed, and it was determined that he had loss of posterior support, major occlusal attrition, relatively good soft tissue health, and existing hard tissues with support for implant restorative solutions. The patient was an ideal candidate for a fixed solution.

FIGURE 1. A healthy male patient in his mid-60s presented with damaged teeth. He requested improved esthetics and functionality, especially for eating.

FIGURE 2. Close-up preoperative frontal view of the patient.

FIGURE 3. Preoperative palatal view.

FIGURE 4. Preoperative occlusal view to assess the patient and develop a treatment plan.

The treatment plan consisted of extracting tooth #16, followed by immediate implant root replacement. Next, the use of a neuromuscular solution to re-establish vertical and trans-horizontal dimension would occur with consideration for the all-ceramic restorations. The final steps included evaluating function and creating the proper esthetics for a healthy, functional, and attractive smile.

Implant Placement
The maxillary right first molar was extracted due to over-eruption and lack of bony support (Fig. 5). After the extraction, the bony architecture was determined to be conducive for immediate implant placement. The implant direction indicator was used to assess angle and depth for the implant (Fig. 6), and a radiograph was taken to ensure that the implant was away from the sinus area and at the appropriate depth (Fig. 7). Once the implant was placed and torqued to 35 Ncm with adequate bone volume, the bony defect was covered with an allograft (Raptos Allograft, Citagenix). The allograft was comprised of cortical, cancellous, and demineralized irradiated bone particulates (Fig.&nbs
p;8).

FIGURE 5. The maxillary right first molar was extracted due to over-eruption and lack of bony support.

FIGURE 6. After immediate extraction of the maxillary right first molar, the implant was placed using an implant direction indicator to assess angle and depth for placement.

FIGURE 7. A radiographic view of the implant was used to ensure that the implant was away from the sinus area, with adequate depth.

FIGURE 8. Once placed, the implant was torqued to 35 Ncm, with adequate bone volume.

After allograft placement, membrane and collagen tape were utilized (Fig. 9). Polytetrafluoroethlyene (PTFE) membranes (Cytoplast, Citagenix) were used to close and achieve proper flap approximation (Fig. 10). A radiograph was taken following implant placement to ensure its accurate location (Fig. 11).

FIGURE 9. Photograph of the membrane and collagen tape.

FIGURE 10. The implant site was covered with PTFE membranes (Cytoplast, Citagenix) and sutured to close the site and achieve proper flap approximation.

FfIGURE 11. Radiograph of the closed implant site.

The maxillary left first and second molars received implants. During surgery, an image was utilized to assess the bone volume, implant angle, and depth of the implants (Fig. 12). Once the implants were placed, healing abutments were attached (Fig. 13). A radiograph was taken to ensure correct placement and healing of the maxillary left first and second molar implants with healing abutments. In the same way, the mandibular right second premolar and first molar received immediate implants, and healing abutments were placed (Fig. 15). A radiograph of the mandibular right second premolar and first molar implants was taken to verify correct placement and proper healing (Fig. 16).

FIGURE 12. During surgery, an image was used to compare the direction of the maxillary left second molar implant with the direction of the maxillary left first molar implant.

FIGURE 13. Once the maxillary first and the second molar implants were placed, healing abutments were attached.

FIGURE 14. A radiograph was taken to verify the placement of the maxillary left first and second molar implants with healing caps.

FIGURE 15. The mandibular right second premolar and first molar were also extracted, immediate implants placed, and healing abutments attached.

FIGURE 16. A radiograph of the two implants was taken to confirm proper positioning and healing.


Restorative Protocol

A neuromuscular approach was used to help find the physiologic position of the mandible in relation to the maxilla. Jaw tracking technology with transcutaneous electro-neural stimulation (Myomonitor TENS Unit, Myotronics) provided the ideal tool to track the patient’s jaw activity. A fixed orthotic was created to simulate the new position, and once waxed was transferred to the patient to ensure a reversible trial with the new bite. After 60 to 90 days of trial wear, the patient was very comfortable, with no signs or symptoms of pain and demonstrated a normal range of motion with smooth opening and closing of the mandible.

Models of the patient’s teeth were created for treatment planning p
urposes. Six points of verification, four posterior and two anterior, were utilized to confirm accuracy (Fig. 17). Fixed and set calipers were used to determine the points on the model. The fixed calipers were used to verify that the intraoral points of measurement on the articulator models were the same as the corresponding points in the mouth (Fig. 18). Orthotics were placed in the mouth on both arches to a fixed determined measurement, which was corroborated with exact measurements reflected on the model and measured again in the mouth (Fig. 19). The orthotics were then measured on the model (Fig. 20). With the fixed maxillary and mandibular orthotics in place, the patient’s bite was assessed (Fig. 21). The bite was determined to be fully intercuspating, with minimal need for adjustments and congruent with the measurements from the articulated models (Fig. 22). The bite was also determined to be functioning in a good mechanical manner, with excellent patient comfort (Fig. 23).

FIGURE 17. Treatment planning models were used, along with six points of verification.

FIGURE 18. The maxillary and mandibular models were placed on an articulator to fix and set the calipers, and to determine if the points on the model accurately corresponded to the intraoral measurements.

FIGURE 19. Orthotics were placed in the mouth on both arches at fixed measurements corresponding exact measurements from the model.

FIGURE 20. Those measurements were re-checked with the fixed points on the model.

FIGURE 21. The fixed maxillary and mandibular orthotics were placed, and the bite was fully intercuspating with minimal adjustments.

FIGURE 22. The bite with orthotics was assessed for comfort and functionality.

FIGURE 23.  Close-up photograph of the patient’s natural smile with the orthotics.

Preparation and Temporization
At the time of preparation, a bite record was created using the articulator bite record to confirm the bite relationship during preparation. It was checked against a fixed caliper to ensure that the bite did not change during the preparation process (Fig. 24). As completed previously, six points of verification were checked on the models and in the mouth (Fig. 25). Initial preparation and indexing of the bite record occurred with bite registration paste (Fig. 26). A radiograph was taken to verify placement with the closed impression copings to ensure proper fit prior to the final impression (Fig. 27). Shade selection was performed to aid in laboratory fabrication of the ceramic restorations (Fig. 28).

FIGURE 24. A bite record was created from the articulator’s bite record to confirm the bite relationship during preparation.

FIGURE 25. The six points of verification, four posterior and two anterior were confirmed on the model and on the patient.

FIGURE 26. Initial preparation and indexing of the bite record occurred with bite registration paste.

FIGURE 27. Radiograph of the closed impression copings to verify proper fit prior to the final impression.

FIGURE 28. The dentin shade was determined and taken to aid in laboratory fabrication of the ceramic restorations.

A fox plane was used to transfer the relationship of the maxilla to the articulator (Stratos Articulator, Ivoclar Vivadent) (Figs. 29 & 30). The bite was indexed in a segmental protocol during preparation to ensure that the trans-horizontal and vertical relationships were not lost while the teeth were prepared (Fig. 31). Temporary stents were placed in the mouth after completing the preparation (Fig. 32). The actual temporaries were placed after the preparation, and the occlusal relationship was assessed (Fig. 33). The temporaries were adjusted and polished (Fig. 34).

FIGURE 29. A fox plane was used to aid in transferring the relationship of the maxilla to articulator.

FIGURE 30. A photograph of the facial view of the fox plane was taken.

FIGURE 31. The bite was indexed in a segmental protocol during preparation to ensure the trans-horizontal and vertical relationships were maintained during preparation.

FIGURE 32. Temporary stents were placed in the patient’s mouth after preparation.

FIGURE 33. Once the temporaries were in place, the occlusal relationship was evaluated.

FIGURE 34. Facial view demonstrating the temporaries adjusted and polished.

Restoration Fabrication
Maxillary and mandibular models were created of the preparation for fabricating titanium custom implant abutments (Procera Esthetic Abutment, Nobel Biocare) (Figs. 35 & 36). Radiographs were taken to verify the fit of the custom abutments to the implant surface (Figs. 37–39). After verification, the maxillary arch was first isolated in a segmental fashion with a split dam technique (Fig. 40). The implant restorations were fabricated from lithium disilicate (IPS e.max, Ivoclar Vivadent) to full contour (Fig. 41). Self-etching adhesive resin cement (Multilink, Ivoclar Vivadent) was used to seat the lithium disilicate crowns (Fig. 42). Once the maxillary arch was completed, the mandibular arch was restored using the same procedure (Figs. 43 & 44). Radiographs were also taken to confirm the implant and restorative fit (Figs. 45 & 46).

FIGURE 35. A maxillary model of the preparation was created with titanium custom implant abutments (Procera Esthetic Abutment, Nobel Biocare).

FIGURE 36. A mandibular model of the preparation was created with titanium custom implant abutments (Procera Esthetic Abutment, Nobel Biocare).

FIGURE 37. A radiograph was taken of the maxillary right first molar implant to ensure that the custom abutments fit to the implant surface.

FIGURE 38. Verification with a radiograph of the custom abutments’ fit to the implant surface of the maxillary left first and second molars was completed.

FIGURE 39. A radiograph of the mandibular right second premolar and first molar was taken to confirm the precise fit to the implant and abutment.

FIGURE 40. The maxillary arch was isolated in a segmental fashion with the split dam technique.

FIGURE 41. The impl
ant supported lithium disilicate (IPS e.max, Ivoclar Vivadent) full contour crown restorations were placed.

FIGURE 42. Right lateral close-up view of the full-contour lithium disilicate crowns.

FIGURE 43. Occlusal close-up view of the maxillary arch with completed restorations.

FIGURE 44. Occlusal close-up view of the mandibular arch with completed restorations.

FIGURE 45. Radiograph of the maxillary right first molar with completed restoration.

FIGURE 46. A radiograph of the mandibular completed restorations was taken to confirm implant and restoration fit.


After two weeks post insertion, the patient’s restorations showed excellent fit and finish, with great gingival response (Fig. 47). Following the completed treatment, the patient’s occlusion and esthetics were refined to stabilize and fine tune the bite and esthetics (Fig. 48). The patient was extremely pleased with the new function, form, and esthetics of his restorations. The 9-month process of extraction, implant placement, healing, integration, occlusion/bite management, smile design, and full mouth rehabilitation demonstrated highly improved function and esthetics (Fig. 49).

FIGURE 47. Close-up retracted view demonstrating the excellent fit and finish, with great gingival response two weeks post insertion.

FIGURE 48. Full facial view following the placement of all restorations—The occlusion and esthetics were refined over four sessions spanning two months.

FIGURE 49. A comparison of preoperative and postoperative images demonstrating the successful smile design and full mouth rehabilitation completed in nine months.

CONCLUSION
Wear, malocclusion, and damaged teeth can cause many problems, including poor esthetics, pain, and decreased function. Through effective treatment planning and smile design, clinicians create a fully restored smile with high esthetics and increased function. The ideal combination of implants, abutments, and all-ceramics can provide patients with stable, functional, durable, and natural-looking restorations. This case demonstrated the use of this combination of materials to ensure a successful treatment and to improve a patient’s quality of life. OH


Dr. Wilson Kwong graduated from the Faculty of Dentistry at the University of British Columbia in 1989. His career and passion for clinical patient care began in a rural community before moving to Vancouver, BC, where he practices today. He currently owns a successful practice in Vancouver, and co-owns a leading-edge practice in Port Moody, BC. As a well-known educator, Dr. Kwong is the current Program Director of the world-renowned Frontier Institute for Advanced Cosmetic Smile Design, Executive Director of the Vancouver Dental Education Centre, and guest lecturer throughout North America. In 2011 he was invited to join the editorial advisory board for the professional journal Compendium. Dr. Kwong is also deeply honoured to recently be designated a Fellow of the American College of Dentistry (FACD).

Oral Health welcomes this original article.

REFERENCES

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8. Lin MH, Mau LP, Cochran DL, et al. Risk assessment of inferior alveolar nerve injury for immediate implant placement in the posterior mandible: a virtual implant placement study. J Dent. 2014 Jan 3. [Epub ahead of print].

9. Shim IK, Chung HJ, Jung MR, et al. Biofunctional porous anodized titanium implants for enhanced bone regeneration. J Biomed Mater Res A. 2013 Nov 6. [Epub ahead of print].

10. Xiropaidis AV, Qahash M, Lim WH, et al. Bone-implant contact at calcium phosphate-coated and porous titanium oxide (TiUnite)-modified oral implants. Clin Oral
Implants Res. 2005;16(5):532-9.

11. Glauser R, Zembic A, Ruhstaller P, et al. Five-year results of implants with an oxidized surface placed predominantly in soft quality bone and subjected to immediate occlusal loading. J Prosthet Dent. 2007;97(6 Suppl):S59-68.

12. McLaren EA, Phong TC. Ceramics in dentistry: classes of materials. Inside Dent. 2009;5(9):94-103.

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15. Reynolds JA, Roberts M. Lithium-disilicate pressed veneers for diastema closure. Inside Dent. 2010;6(5):46-52.


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1 Comment » for Full Mouth Rehabilitation with Lithium Disilicate Crowns and Titanium Abutments
  1. vrej adjemian says:

    I Take Lithium for the past 20 years.
    I would like to know if I could do implants.
    Thank you.

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