Short Communication Tim Joda €gger Urs Bra

Complete digital workflow for the production of implant-supported single-unit monolithic crowns

Authors’ affiliations: Tim Joda & Urs Br€ agger, Division of Fixed Prosthodontics, School of Dental Medicine, University of Bern, Freiburgstr. 7, CH-3010 Bern, Switzerland Tim Joda, Department of Prosthetic Dentistry, Center for Dental and Oral Medicine, University Hospital Hamburg-Eppendorf, Martinistr. 52, O52, D-20146, Hamburg, Germany

Key words: cad/cam, dental crown, dental implant, digital workflow, intraoral optical scan,

Corresponding author: Dr Tim Joda DMD, MSc Division of Fixed Prosthodontics School of Dental Medicine University of Bern Freiburgstr. 7, CH-3010 Bern, Switzerland Tel.: +41 (0)31 / 632-0910 Fax: +41 (0)31 / 632-4931 e-mail: [email protected]

nano ceramic (RNC). Starting with an intraoral optical scan (IOS), and following a CAD/CAM

resin nano ceramic (RNC) Abstract Objectives: The aim of this case series was to introduce a complete digital workflow for the production of monolithic implant crowns. Material and methods: Six patients were treated with implant-supported crowns made of resin process, the monolithic crowns were bonded either to a novel prefabricated titanium abutment base (group A) or to a CAD/CAM-generated individualized titanium abutment (group B) in premolar or molar sites on a soft tissue level dental implant. Economic analyses included clinical and laboratory steps. An esthetic evaluation was performed to compare the two abutment-crown combinations. Results: None of the digitally constructed RNC crowns required any clinical adaptation. Overall mean work time calculations revealed obvious differences for group A (65.3 min) compared with group B (86.5 min). Esthetic analysis demonstrated a more favorable outcome for the prefabricated bonding bases. Conclusions: Prefabricated or individualized abutments on monolithic RNC crowns using CAD/CAM technology in a model-free workflow seem to provide a feasible and streamlined treatment approach for single-edentulous space rehabilitation in the posterior region. However, RNC as fullcontour material has to be considered experimental, and further large-scale clinical investigations with long-term follow-up observation are necessary.

Date: Accepted 28 August 2013 To cite this article: Joda T, Br€agger U. Complete digital workflow for the production of implant-supported single-unit monolithic crowns. Clin. Oral Impl. Res. 25, 2014, 1304–1306 doi: 10.1111/clr.12270

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The construction of monolithic crowns on teeth is an established procedure (Beuer et al. 2012). Implant prosthodontics may also profit from the digital CAD/CAM technology in the production of full-contour reconstructions (Patel 2010). Therefore, the combination of high-strength monolithic materials connected to abutment substructures may represent a preferable treatment alternative, especially in the posterior region. A recently defined material class – resin nano ceramic (RNC) – composed of bonded zirconia–silica nanoparticles, clustered and embedded in a cross-linked resin matrix, has been introduced for the CAD/CAM fabrication of fixed reconstructions (Lava Ultimate Restorative, 3M ESPE, Neuss, Germany) (Koller et al. 2012). However, no valid clinical data, related to implant-supported RNC crowns, are presently available in the scientific literature. The aim of this Short Communication was to present, as a proof-of-principle, a new pro-

duction concept for monolithic implant-supported single-unit reconstructions made of RNC combined with a novel bonding base or an individualized abutment.

Materials and methods Baseline of this clinical case series started with the prosthetic rehabilitation. A total of six patients with a single-edentulous space including neighboring teeth in premolar and molar sites were included to receive monolithic RNC crowns on a tissue level dental implant (Institute Straumann AG, Basel, Switzerland). After the digital transfer of the implant platform position with a quadrant-like partially intraoral optical scan (IOS) (iTero Scanner, Align Technology Inc., San Jose, CA, USA), all reconstructions were virtually designed as fully anatomical 1-piece transocclusal screw-retained crowns. Patients

© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

Joda & Br€agger  Implant-supported single-unit monolithic crowns

were assigned to group A with novel prefabricated titanium abutments (Straumann VariobaseTM Abutment, Institute Straumann AG, Basel, Switzerland) and group B with CAD/ CAM-generated individualized titanium abutments (Straumann CARESâ Abutment, Institute Straumann AG, Basel, Switzerland). The electronic STL data of the virtual patient situation were sent to an external milling center for the CAD/CAM fabrication of full-contour reconstructions in a modelfree process. Subsequently, the implant crowns were bonded to either the abutments of group A or group B (Multilink Implant, Ivoclar Vivadent, Schaan, Liechtenstein) and individually finalized with painting in the dental laboratory (Fig. 1 and 2). As primary outcome, economic analyses with time assessment and cost calculations for prosthetic treatment as well as laboratory work steps were performed and compared. Clinical treatment included as follows:

• •



IOS – removal and insertion of healing cap and scanbody, optical impression taking of implant site and opposite arch, digital bite registration, color determination; Prosthetic placement – removal of healing cap, adaptation of implant-supported RNCcrown, final insertion, closure of the access hole with provisional composite. Laboratory work steps consisted of: Data processing the monolithic

(a)

– virtual design of RNC reconstruction



(groups A, B) and of the individualized abutment (only group B); Completion of the reconstruction – adaptation of the appropriate abutment type to the crown, painting, and polishing.

Moreover, the interproximal and occlusal fit of the reconstructions were examined, and the esthetic appearance was evaluated with the White Esthetic Score (WES) (Belser et al. 2009).

Results All digitally generated implant RNC crowns did not require any interproximal or occlusal adaptation, independent of the abutment used. In addition, the clinical treatment could be managed during two appointments for (1) IOS and (2) prosthetic placement, with a mean total chair time of 18.5 min per patient / reconstruction. The technical manufacturing process for RNC crowns mounted on the novel bonding base abutments was less time-consuming than for the individualized abutments. The mean overall time analyses revealed obvious differences for group A (65.3 min) compared with group B (86.5 min) (Table 1). The dentist’s fee for implant crowns made of prefabricated or individualized abutments did not differ according to the Swiss tariff system for dental medicine (SSO). However, total laboratory costs were lower for group A

(b)

with a total of 650 Swiss francs compared with group B with 785 Swiss francs due to lower-priced material costs for the prefabricated bonding base plus reduced work time by saving of virtually designing and technical preparation of the abutment. The full-contour RNC crowns, bonded on the individualized abutments, showed a slightly greyish appearance in the cervical area. This phenomenon was not evident in group A with the novel bonding base abutment design. For group A, the mean WES was 7.3 and for group B 5.7.

Discussion It is of great interest to offer the advantages of implant-supported reconstructions to more patients. This can be accomplished by reducing the overall clinical treatment time and the technical production process to achieve a reasonable cost-benefit ratio in combination with high quality and precision of the prosthetic reconstructions (Bragger et al. 2005; Bouchard et al. 2009). Technical development in the field of digital dental medicine has opened the opportunity for fully anatomical monolithic implant-supported reconstructions (Fasbinder 2010; Patel 2010). The entire fabrication process, starting clinically with an IOS, and following digital designing without any physical models, is simplified by having the

(c)

(d)

Fig. 1. Patient #1 (group A): Intraoral optical scan (1a) and digitally fabricated monolithic crown made of RNC bonded to a novel prefabricated titanium implant abutment (Straumann, Variobase™ Abutment, Institute Straumann AG, Basel, Switzerland) (1b) as well as final clinical situation with inserted one-piece screw-retained full-contour reconstruction in region 45 from vestibular (1c) and occlusal (1d).

(a)

(b)

(c)

(d)

Fig. 2. Patient #4 (group B): Intraoral optical scan (2a) and digitally fabricated monolithic crown made of RNC bonded to an individualized titanium abutment (Straumann CARESâ Abutment, Institute Straumann AG, Basel, Switzerland) (2b) as well as final clinical situation with inserted one-piece screw-retained full-contour reconstruction in region 35 from vestibular (2c) and occlusal (2d).

© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

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Joda & Br€ agger  Implant-supported single-unit monolithic crowns

Table 1. Implant-specific characteristics and FDI locations for prefabricated bonding base abutments (group A) and individualized abutments (group B) as well as clinical treatment and laboratory work steps in time units per minutes. Patient

Clinic time

RNC implant crown

Intraoral scan (min)

Group A Bonding base abutment #1: FDI 45 11.0 TL RN 4.8 mm #2: FDI 46 10.5 TL WN 6.5 mm #3: FDI 36 12.0 TL WN 6.5 mm Total Ø 11.2 Group B Individualized abutment #4: FDI 35 11.5 TL RN 4.8 mm #5: FDI 36 10.0 TL WN 6.5 mm #6: FDI 25 12.0 TL RN 4.8 mm Total Ø 11.2

Laboratory time Prosthetic placement (min)

Manufacturing process (min)

Total (min)

6.5

45.0

62.5

7.5

48.5

66.5

8.0

47.0

67.0

Ø 7.3

Ø 46.8

Ø 65.3

7.0

64.5

83.0

8.5

71.5

90.0

6.5

68.0

86.5

Ø 7.3

Ø 68.0

Ø 86.5

option of connecting a monolithic crown to prefabricated or individualized abutments (Kapos et al. 2009; Lee & Gallucci 2013). The findings of this clinical case series revealed that fully anatomical implant-supported crowns made of RNC are a feasible treatment concept in the fully digital work-

flow. Partially quadrant-like IOS and CAD/ CAM technology in combination with prefabricated or individualized abutments seem to offer a streamlined treatment approach for single-tooth replacement in posterior sites.

According to economic considerations, patients would even benefit more from the new concept of monolithic implant RNC crowns connected to the prefabricated bonding base abutments. In addition, esthetic analyses showed a more favorable result for the novel bonding base abutments by means of providing adequate space for the translucent RNC-crown material. Overall, it is clearly emphasized that RNC, as material for implant-supported monolithic crowns, has to be considered experimental. No other clinical data are available in the scientific literature. Further large-scale studies with long-term follow-up observations are necessary to investigate the clinical performance of the treatment concept with fullcontour implant-supported RNC crowns.

Acknowledgements: The authors acknowledge the dental laboratory Flury, Bern, Switzerland, for manufacturing the implant-supported RNC crowns. Furthermore, they thank Institute Straumann AG, Basel, Switzerland, for their support of the study by donating the implant prosthetic components.

References Belser, U.C., Grutter, L., Vailati, F., Bornstein, M.M., Weber, H.P. & Buser, D. (2009) Outcome evaluation of early placed maxillary anterior single-tooth implants using objective esthetic criteria: a cross-sectional, retrospective study in 45 patients with a 2- to 4-year follow-up using pink and white esthetic scores. Journal of Periodontology 80: 140–151. Beuer, F., Stimmelmayr, M., Gueth, J.F., Edelhoff, D. & Naumann, M. (2012) In vitro performance of full-contour zirconia single crowns. Dental Materials: Official Publication of the Academy of Dental Materials 28: 449–456. Bouchard, P., Renouard, F., Bourgeois, D., Fromentin, O., Jeanneret, M.H. & Beresniak, A. (2009) Cost-

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effectiveness modeling of dental implant vs Bridge. Clinical Oral Implants Research 20: 583–587. Bragger, U., Krenander, P. & Lang, N.P. (2005) Economic aspects of single-tooth replacement. Clinical Oral Implants Research 16: 335–341. Fasbinder, D.J. (2010) Digital dentistry: innovation for restorative treatment. Compendium of Continuing Education in Dentistry 31 Spec No 4: 2–11. quiz 12. Kapos, T., Ashy, L.M., Gallucci, G.O., Weber, H.P. & Wismeijer, D. (2009) Computer-aided design and computer-assisted manufacturing in prosthetic implant dentistry. International Journal of Oral and Maxillofacial Implants 24(Suppl): 110–117.

Koller, M., Arnetzl, G.V., Holly, L. & Arnetzl, G. (2012) Lava ultimate resin nano ceramic for cad/cam: customization case study. International Journal of Computerized Dentistry 15: 159–164. Lee, S.J. & Gallucci, G.O. (2013) Digital versus conventional implant impressions: efficiency outcomes. Clinical Oral Implants Research 24: 111– 115. Patel, N. (2010) Integrating three-dimensional digital technologies for comprehensive implant dentistry. Journal of the American Dental Association 141(Suppl 2): 20s–24s.

© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd

Complete digital workflow for the production of implant-supported single-unit monolithic crowns.

The aim of this case series was to introduce a complete digital workflow for the production of monolithic implant crowns...
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