journal of prosthodontic research 59 (2015) 152–158
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/jpor
Technical procedure
In silico comparison of the reproducibility of full-arch implant provisional restorations to final restoration between a 3D Scan/CAD/CAM technique and the conventional method Takuya Mino DDS, PhDa, Kenji Maekawa DDS, PhDb, Akihiro Ueda DTb, Shizuo Higuchi DTc, Junichi Sejima DTb, Tetsuo Takeuchi DTb, Emilio Satoshi Hara DDS, PhDa, Aya Kimura-Ono DDS, PhDa, Wataru Sonoyama DDS, PhDa, Takuo Kuboki DDS, PhDa,* a
Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Japan b Dental Laboratories, Hospital Medical Technology Part, Okayama University Hospital, Japan c Wada Precision Dental Laboratories, Japan
article info
abstract
Article history:
Purpose: The aim of this article was to investigate the accuracy in the reproducibility of full-
Received 28 February 2014
arch implant provisional restorations to final restorations between a 3D Scan/CAD/CAM
Received in revised form
technique and the conventional method.
22 December 2014
Methods: We fabricated two final restorations for rehabilitation of maxillary and mandibular
Accepted 22 December 2014
complete edentulous area and performed a computer-based comparative analysis of the
Available online 23 January 2015
accuracy in the reproducibility of the provisional restoration to final restoration between a
Keywords:
transfer technique. Final restorations fabricated either by the conventional or Scan/CAD/
Accurate transfer
CAM method were successfully installed in the patient. The total concave/convex volume
3D scanning and CAD/CAM (Scan/CAD/CAM) technique and the conventional silicone-mold
Implant final restoration
discrepancy observed with the Scan/CAD/CAM technique was 503.50 mm3 and 338.15 mm3
In silico analysis
for maxillary and mandibular implant-supported prostheses (ISPs), respectively. On the
Provisional restoration Scan/CAD/CAM technique
other hand, total concave/convex volume discrepancy observed with the conventional method was markedly high (1106.84 mm3 and 771.23 mm3 for maxillary and mandibular ISPs, respectively). Conclusions: The results of the present report suggest that Scan/CAD/CAM method enables a more precise and accurate transfer of provisional restorations to final restorations compared to the conventional method. # 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.
* Corresponding author at: Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8525, Japan. Tel.: +81 86 235 6680; fax: +81 86 235 6684. E-mail address: [email protected] (T. Kuboki). http://dx.doi.org/10.1016/j.jpor.2014.12.001 1883-1958/# 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.
journal of prosthodontic research 59 (2015) 152–158
1.
153
Introduction
Detailed adjustment of provisional restorations of implantsupported prostheses (ISPs) are crucial to determine overall success and patient’s satisfaction with the final restoration in terms of occlusion, tooth shape, function and esthetics [1]. At the same time, provisional restorations enable testing of shape and contour of ISPs as to achieve an easy cleaning, without allowing for food accumulation, between alveolar ridge and the suprastructure. Several attempts have been made to obtain accurate transfer (copy) of the provisional restoration during confection of the final restoration, such as preparation of plaster casts [2– 4]. However, no current technique can reproduce the details of the provisional restoration without significant distortions, which consequently, make additional adjustments in the final restoration necessary. In an attempt to avoid unnecessary adjustment steps and time during installation of the final restoration, new approaches based on computer-aided design and computer-aided manufacturing (CAD/CAM) techniques have been developed for digital impression [5] and could potentially reproduce (copy) the provisional restoration with great accuracy. Based on this concept, we attempted to develop a novel technique to fabricate the final restoration of ISPs for full edentulous cases using a combination of 3D scanning and CAD/CAM (Scan/CAD/CAM) technique to obtain a more fine copy of the details of provisional restoration [6]. In this report, we fabricated two final restorations for rehabilitation of maxillary and mandibular complete edentulous area and performed an in silico analysis of the reproducibility of the Scan/CAD/CAM technique to replace the shape of provisional restoration to final restoration, in comparison with the conventional transfer technique.
2.
Materials and methods
2.1.
Case
A 67-year-old male patient, who had complete missing teeth in both maxillary and mandibular arches, received six implant fixtures (ø3.3 mm 10.0 mm Bra˚nemark Mk III narrow platform TiUnite at lower incisal regions, ø3.75 mm 11.5 mm regular platform TiUnite at lower four molar regions, and ø4.0 mm 11.5 mm regular platform Nobel Speedy at upper all six regions; Nobel Biocare, Sweden) and provisional boneanchored bridges in both arches (Figs. 1 and 2). Adjustments on the provisional restorations were performed before transfer procedure. After the installation of provisional restorations, adjustments were performed in the basal surface to obtain easy cleaning, as well as in the position of artificial teeth with further detailed occlusal adjustments in order to obtain a balanced occlusion in centric position and during lateral and protrusive movements. These adjustments were carried out throughout a period of four months (a total of 7 visits), and eventually the patient became satisfied with the final condition of the provisional restorations both functionally and esthetically. The patient was then explained about the purpose of the study and informed consent was obtained before the study onset.
Fig. 1 – Panoramic radiographs of the patient. Six implant fixtures were placed in both maxilla and mandible arches.
Fig. 2 – Intraoral view. Bone-anchored provisional bridges were installed in both arches and adjusted in order to achieve satisfactory functional and cleanable architecture. (A) Frontal view; (B) maxillary occlusal view; and (C) mandibular occlusal view.
2.2. Fabrication of final restorations by the conventional method First, impression was taken from provisional restorations directly in the patient’s oral cavity with alginate impression
154
journal of prosthodontic research 59 (2015) 152–158
Fig. 3 – Fabrication of final restorations by the conventional method. (A) Abutment level impression. (B) Lower provisional restoration was placed on the respective working cast and mounted on the articulator at the occluded condition with study cast of antagonistic teeth. (C) Mucosal surface shapes of both upper and lower provisional restorations were recorded using laboratory silicone putty. (D) Trial of both upper and lower wax dentures. (E) Upper final restoration fabricated by the conventional technique.
Fig. 4 – Pictures of the provisional restorations (A), provisional restorations mounted on the working cast (B), and working casts with connected cylinders for laboratory work (C). Restorations and casts were scanned with a 3D scanner and rerecreated by using a CAD software (D–F).
Fig. 5 – Final restorations were shaped on a ZENO zirconia translucent disk by a 5-axis milling machine (A). (B) Occlusal view of the milled zirconia frame. (C) Mucosal surface of the milled zirconia frame.
material (Aroma Fine Plus, GC Corporation, Japan), for preparation of upper and lower study casts. Additionally, impression of abutments and alveolar ridges were taken to obtain upper and lower working casts. Before taking the impressions, copings
(Impression Coping Open Tray Multi-unit, Nobel Biocare, Sweden) were connected to each abutment and fixed using a quick self-curing acrylic resin (FIXPEED, GC Corporation, Japan). Final impressions were taken using a silicone-based impression
journal of prosthodontic research 59 (2015) 152–158
155
Fig. 6 – Application of color staining to tooth crown and gingival area in Scan/CAD/CAM final restorations.
material (ImprintTM II GarantTM, 3M ESPE, USA) and an open tray (Fig. 3A). After preparation of the working casts, provisional restorations were placed on the working casts and mounted on the articulator, and lateral and protrusive sliding movements were recorded on the laboratory silicone putty (Protesil labor, Vennini Dental, Italy). Additionally, mucosal shapes of both upper and lower ridges were recorded with using laboratory silicone putty to serve as basis for confection of titanium frame and determination of gingival margin of the final restorations. Artificial teeth were mounted on wax based on the recorded movement of incisal guide pin on the silicon putty, and the wax denture inserted for additional intraoral occlusal adjustments. Final restorations were then fabricated based on the wax denture, with acrylic resin and reinforced with titanium frame (Fig. 3).
3.
Difference from convention method
3.1. Fabrication of final restorations by the Scan/CAD/ CAM technique The procedure for fabrication of final restorations by the Scan/ CAD/CAM technique was performed according to the study of Higuchi et al. [6]. A 3D scanner (D-710, 3Shape, Denmark) was used to scan the provisional restorations and working casts. The occlusal, lingual/palatal and buccal surfaces of the provisional restorations were scanned from the provisional restorations fixed in position onto the working cast. Additionally, the base of the provisional restoration, corresponding to the area in contact with the mucosa model, was scanned from the provisional restoration fixed vertically on a supporter (Fig. 4). Finally, the working casts with cylinders were also scanned to obtain information about the position of the guide pins and access holes. The scanned images were then recreated in silico using a CAD software (Dental Designer, 3Shape, Denmark) (Fig. 4). Next, upper and lower full-zirconia final restorations were fabricated based on the scanned data on a ZENO zirconia translucent disk (Daishin Trading Co., Japan) by a 5-axis milling machine (RXP500 DSC, Ro¨ders, Germany) (Fig. 5). Final restorations were then immersed into a staining solution (ZENOSTAR Color Zr, Wieland Dental, Germany) and baked. After coloring the frames, restorations were mounted on the articulator and occlusal adjustment was performed. Subsequently, surface
Fig. 7 – Final restorations fabricated by Scan/CAD/CAM technique. (A) Upper final restoration and (B) lower final restoration.
stain color were applied to tooth crowns and gingival area (Fig. 6) and glazed. After the full zirconia restorations were fabricated, the internal areas of the access holes that connect to abutment cylinders were sandblasted and treated with A.Z. Primer (SHOFU, Japan). At the same time, abutment cylinders (Gold cylinder, Nobel Biocare, Sweden) were pretreated with M.L. Primer (SHOFU, Japan) and fixed with screws onto the implants. The access holes in the zirconia restorations were then filled with adhesive cement (Resicem, SHOFU, Japan), and the zirconia restoration and abutment cylinders were fixed together (Fig. 7). Fig. 8 shows the final restorations fabricated by the conventional or the 3D Scan/CAD/CAM technique after
156
journal of prosthodontic research 59 (2015) 152–158
Fig. 8 – Installed final restorations fabricated by either Scan/CAD/CAM technique ((A) occlusal view of maxillary ISP, (B) frontal view, (C) occlusal view of mandibular ISP) or conventional method ((D) occlusal view of maxillary ISP, (E) frontal view, (F) occlusal view of mandibular ISP).
Fig. 9 – Shape discrepancies calculated using the superposed images of scanned data of final and provisional restorations fabricated using the two different techniques. Total volume difference of convex/concave portions of final restorations relative to the provisional restorations was small by fabrication with Scan/CAD/CAM technique.
installation in the patient. Visual analysis of the final restorations indicated a more precise copy of the provisional restoration (Fig. 2) by the 3D Scan/CAD/CAM method. However, the patient could not sense differences between the shape and volume of the two final restorations. Therefore, in order to quantitatively assess and demonstrate the difference between the two techniques, we subsequently performed a computerbased 3D analysis of the final restorations.
3.2. In silico comparison of reproducibility between provisional and final restorations Two final restorations fabricated by different techniques and provisional restorations were scanned with a 3D scanner (Rexcan ARX, Solutionix, Korea) with accuracy 20 mm and images were superimposed using an imaging software (FreeForm, SensAble Technologies, USA). Discrepancies in
journal of prosthodontic research 59 (2015) 152–158
157
Fig. 10 – Shape discrepancies between final and provisional restorations displayed as color tones. Green area was dominant in images of Scan/CAD/CAM restorations, whereas a gray area was predominant in restorations fabricated by the conventional method.
the shape between final and provisional restoration were determined by the difference in total volume of the geometry of concave and convex portions of each final restoration relative to the provisional restoration using the FreeForm imaging software. This software can perform an automatic alignment and superimposition in one coordinate system of the two restorations, based on the best match of these selections. Best-fit alignment used 300 randomly selected points to get an initial operation [7]. Next, the sample size was automatically increased to 1500, and a further fine adjustment was performed to achieve the final alignment. Using this technique, images of final and provisional restorations were overlaid and difference in surface shape was measured and expressed in color tones using a different imaging software (EZ scan, Solutionix, Korea). Parts with no surface shape difference are shown in green, parts of 0.4 mm convex are expressed in red, and 0.3 mm concave parts are shown in blue. When the surface shape difference is more than the detection limit, these parts are displayed in gray. Color tones changes gradually in correspondence to the differences in surface shape.
4.
Effect or performance
First, final restorations fabricated either by the conventional or Scan/CAD/CAM method were successfully installed in the patient. Analysis of shape discrepancies between provisional and final restorations fabricated by both techniques revealed a more accurate copy of the details of the provisional restoration by Scan/CAD/CAM technique, with a total concave/convex volume discrepancy of 503.50 mm3 and 338.15 mm3 for maxillary and mandibular ISPs, respectively. On the other hand, total concave/convex volume discrepancy observed with the conventional method was markedly high (1106.84 mm3 and 771.23 mm3) for maxillary and mandibular ISPs, respectively (Fig. 9). Analysis of surface shape discrepancies by color tone showed a predominant green area in the images of restorations fabricated by Scan/CAD/CAM technique. However, gray
color was dominant in the final restorations fabricated by the conventional technique (Fig. 10).
5.
Conclusions
Within the limitation of this study, this Scan/CAD/CAM method showed the more precise and accurate than the conventional method at the time of transferring the provisional restorations to the final restorations. However, this method is only applicable in cases of fabrication of final restorations from a single material (e.g. zirconia, titanium) and still requires improvement in esthetics compared to final restorations fabricated with plural materials such as porcelain, hybrid ceramics and acrylic resin. In the future, it is necessary to create new digital techniques to fabricate Scan/ CAD/CAM restorations using plural materials. Additionally, we intend to create new digital techniques to accurately reproduce provisional restorations of conventional crowns/ bridges to final restorations, which is presently problematic due to lack of clear reference point in the working casts, which in turn, does not enable overlay of the scanned images.
Conflict of interest The authors declare that there are no conflicts of interest.
references
[1] Moscovitch MS, Saba S. The use of a provisional restoration in implant dentistry: a clinical report. Int J Oral Maxillofac Implants 1996;11:395–9. [2] Buskin R, Salinas TJ. Transferring emergence profile created from the provisional to the definitive restoration. Pract Periodontics Aesthet Dent 1998;10:1171–9. quiz 1180. [3] Breeding LC, Dixon DL. Transfer of gingival contours to a master cast. J Prosthet Dent 1996;75:341–3.
158
journal of prosthodontic research 59 (2015) 152–158
[4] Elian N, Tabourian G, Jalbout ZN, Classi A, Cho SC, Froum S, et al. Accurate transfer of peri-implant soft tissue emergence profile from the provisional crown to the final prosthesis using an emergence profile cast. J Esthet Restor Dent 2007;19:306–14. [5] Goodacre CJ, Garbacea A, Naylor WP, Daher T, Marchack CB, Lowry J. CAD/CAM fabricated complete dentures: concepts and clinical methods of obtaining required morphological data. J Prosthet Dent 2012;107:34–46.
[6] Higuchi S, Yamaji Y, Mino T, Kuboki T, Wada O, Wada H. A technique to replace provisional restoration with final prosthesis which fit to oral function. J Jpn Soc Dent Prod 2012;2:37–44. [7] Gonza´lez-Martı´n O, Veltri M, Mora´guez O, Belser UC. Quantitative three-dimensional methodology to assess volumetric and profilometric outcome of subepithelial connective tissue grafting at pontic sites: a prospective pilot study. Int J Periodontics Restorative Dent 2014;34:673–9.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/jpor
Technical procedure
In silico comparison of the reproducibility of full-arch implant provisional restorations to final restoration between a 3D Scan/CAD/CAM technique and the conventional method Takuya Mino DDS, PhDa, Kenji Maekawa DDS, PhDb, Akihiro Ueda DTb, Shizuo Higuchi DTc, Junichi Sejima DTb, Tetsuo Takeuchi DTb, Emilio Satoshi Hara DDS, PhDa, Aya Kimura-Ono DDS, PhDa, Wataru Sonoyama DDS, PhDa, Takuo Kuboki DDS, PhDa,* a
Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Japan b Dental Laboratories, Hospital Medical Technology Part, Okayama University Hospital, Japan c Wada Precision Dental Laboratories, Japan
article info
abstract
Article history:
Purpose: The aim of this article was to investigate the accuracy in the reproducibility of full-
Received 28 February 2014
arch implant provisional restorations to final restorations between a 3D Scan/CAD/CAM
Received in revised form
technique and the conventional method.
22 December 2014
Methods: We fabricated two final restorations for rehabilitation of maxillary and mandibular
Accepted 22 December 2014
complete edentulous area and performed a computer-based comparative analysis of the
Available online 23 January 2015
accuracy in the reproducibility of the provisional restoration to final restoration between a
Keywords:
transfer technique. Final restorations fabricated either by the conventional or Scan/CAD/
Accurate transfer
CAM method were successfully installed in the patient. The total concave/convex volume
3D scanning and CAD/CAM (Scan/CAD/CAM) technique and the conventional silicone-mold
Implant final restoration
discrepancy observed with the Scan/CAD/CAM technique was 503.50 mm3 and 338.15 mm3
In silico analysis
for maxillary and mandibular implant-supported prostheses (ISPs), respectively. On the
Provisional restoration Scan/CAD/CAM technique
other hand, total concave/convex volume discrepancy observed with the conventional method was markedly high (1106.84 mm3 and 771.23 mm3 for maxillary and mandibular ISPs, respectively). Conclusions: The results of the present report suggest that Scan/CAD/CAM method enables a more precise and accurate transfer of provisional restorations to final restorations compared to the conventional method. # 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.
* Corresponding author at: Department of Oral Rehabilitation and Regenerative Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8525, Japan. Tel.: +81 86 235 6680; fax: +81 86 235 6684. E-mail address: [email protected] (T. Kuboki). http://dx.doi.org/10.1016/j.jpor.2014.12.001 1883-1958/# 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.
journal of prosthodontic research 59 (2015) 152–158
1.
153
Introduction
Detailed adjustment of provisional restorations of implantsupported prostheses (ISPs) are crucial to determine overall success and patient’s satisfaction with the final restoration in terms of occlusion, tooth shape, function and esthetics [1]. At the same time, provisional restorations enable testing of shape and contour of ISPs as to achieve an easy cleaning, without allowing for food accumulation, between alveolar ridge and the suprastructure. Several attempts have been made to obtain accurate transfer (copy) of the provisional restoration during confection of the final restoration, such as preparation of plaster casts [2– 4]. However, no current technique can reproduce the details of the provisional restoration without significant distortions, which consequently, make additional adjustments in the final restoration necessary. In an attempt to avoid unnecessary adjustment steps and time during installation of the final restoration, new approaches based on computer-aided design and computer-aided manufacturing (CAD/CAM) techniques have been developed for digital impression [5] and could potentially reproduce (copy) the provisional restoration with great accuracy. Based on this concept, we attempted to develop a novel technique to fabricate the final restoration of ISPs for full edentulous cases using a combination of 3D scanning and CAD/CAM (Scan/CAD/CAM) technique to obtain a more fine copy of the details of provisional restoration [6]. In this report, we fabricated two final restorations for rehabilitation of maxillary and mandibular complete edentulous area and performed an in silico analysis of the reproducibility of the Scan/CAD/CAM technique to replace the shape of provisional restoration to final restoration, in comparison with the conventional transfer technique.
2.
Materials and methods
2.1.
Case
A 67-year-old male patient, who had complete missing teeth in both maxillary and mandibular arches, received six implant fixtures (ø3.3 mm 10.0 mm Bra˚nemark Mk III narrow platform TiUnite at lower incisal regions, ø3.75 mm 11.5 mm regular platform TiUnite at lower four molar regions, and ø4.0 mm 11.5 mm regular platform Nobel Speedy at upper all six regions; Nobel Biocare, Sweden) and provisional boneanchored bridges in both arches (Figs. 1 and 2). Adjustments on the provisional restorations were performed before transfer procedure. After the installation of provisional restorations, adjustments were performed in the basal surface to obtain easy cleaning, as well as in the position of artificial teeth with further detailed occlusal adjustments in order to obtain a balanced occlusion in centric position and during lateral and protrusive movements. These adjustments were carried out throughout a period of four months (a total of 7 visits), and eventually the patient became satisfied with the final condition of the provisional restorations both functionally and esthetically. The patient was then explained about the purpose of the study and informed consent was obtained before the study onset.
Fig. 1 – Panoramic radiographs of the patient. Six implant fixtures were placed in both maxilla and mandible arches.
Fig. 2 – Intraoral view. Bone-anchored provisional bridges were installed in both arches and adjusted in order to achieve satisfactory functional and cleanable architecture. (A) Frontal view; (B) maxillary occlusal view; and (C) mandibular occlusal view.
2.2. Fabrication of final restorations by the conventional method First, impression was taken from provisional restorations directly in the patient’s oral cavity with alginate impression
154
journal of prosthodontic research 59 (2015) 152–158
Fig. 3 – Fabrication of final restorations by the conventional method. (A) Abutment level impression. (B) Lower provisional restoration was placed on the respective working cast and mounted on the articulator at the occluded condition with study cast of antagonistic teeth. (C) Mucosal surface shapes of both upper and lower provisional restorations were recorded using laboratory silicone putty. (D) Trial of both upper and lower wax dentures. (E) Upper final restoration fabricated by the conventional technique.
Fig. 4 – Pictures of the provisional restorations (A), provisional restorations mounted on the working cast (B), and working casts with connected cylinders for laboratory work (C). Restorations and casts were scanned with a 3D scanner and rerecreated by using a CAD software (D–F).
Fig. 5 – Final restorations were shaped on a ZENO zirconia translucent disk by a 5-axis milling machine (A). (B) Occlusal view of the milled zirconia frame. (C) Mucosal surface of the milled zirconia frame.
material (Aroma Fine Plus, GC Corporation, Japan), for preparation of upper and lower study casts. Additionally, impression of abutments and alveolar ridges were taken to obtain upper and lower working casts. Before taking the impressions, copings
(Impression Coping Open Tray Multi-unit, Nobel Biocare, Sweden) were connected to each abutment and fixed using a quick self-curing acrylic resin (FIXPEED, GC Corporation, Japan). Final impressions were taken using a silicone-based impression
journal of prosthodontic research 59 (2015) 152–158
155
Fig. 6 – Application of color staining to tooth crown and gingival area in Scan/CAD/CAM final restorations.
material (ImprintTM II GarantTM, 3M ESPE, USA) and an open tray (Fig. 3A). After preparation of the working casts, provisional restorations were placed on the working casts and mounted on the articulator, and lateral and protrusive sliding movements were recorded on the laboratory silicone putty (Protesil labor, Vennini Dental, Italy). Additionally, mucosal shapes of both upper and lower ridges were recorded with using laboratory silicone putty to serve as basis for confection of titanium frame and determination of gingival margin of the final restorations. Artificial teeth were mounted on wax based on the recorded movement of incisal guide pin on the silicon putty, and the wax denture inserted for additional intraoral occlusal adjustments. Final restorations were then fabricated based on the wax denture, with acrylic resin and reinforced with titanium frame (Fig. 3).
3.
Difference from convention method
3.1. Fabrication of final restorations by the Scan/CAD/ CAM technique The procedure for fabrication of final restorations by the Scan/ CAD/CAM technique was performed according to the study of Higuchi et al. [6]. A 3D scanner (D-710, 3Shape, Denmark) was used to scan the provisional restorations and working casts. The occlusal, lingual/palatal and buccal surfaces of the provisional restorations were scanned from the provisional restorations fixed in position onto the working cast. Additionally, the base of the provisional restoration, corresponding to the area in contact with the mucosa model, was scanned from the provisional restoration fixed vertically on a supporter (Fig. 4). Finally, the working casts with cylinders were also scanned to obtain information about the position of the guide pins and access holes. The scanned images were then recreated in silico using a CAD software (Dental Designer, 3Shape, Denmark) (Fig. 4). Next, upper and lower full-zirconia final restorations were fabricated based on the scanned data on a ZENO zirconia translucent disk (Daishin Trading Co., Japan) by a 5-axis milling machine (RXP500 DSC, Ro¨ders, Germany) (Fig. 5). Final restorations were then immersed into a staining solution (ZENOSTAR Color Zr, Wieland Dental, Germany) and baked. After coloring the frames, restorations were mounted on the articulator and occlusal adjustment was performed. Subsequently, surface
Fig. 7 – Final restorations fabricated by Scan/CAD/CAM technique. (A) Upper final restoration and (B) lower final restoration.
stain color were applied to tooth crowns and gingival area (Fig. 6) and glazed. After the full zirconia restorations were fabricated, the internal areas of the access holes that connect to abutment cylinders were sandblasted and treated with A.Z. Primer (SHOFU, Japan). At the same time, abutment cylinders (Gold cylinder, Nobel Biocare, Sweden) were pretreated with M.L. Primer (SHOFU, Japan) and fixed with screws onto the implants. The access holes in the zirconia restorations were then filled with adhesive cement (Resicem, SHOFU, Japan), and the zirconia restoration and abutment cylinders were fixed together (Fig. 7). Fig. 8 shows the final restorations fabricated by the conventional or the 3D Scan/CAD/CAM technique after
156
journal of prosthodontic research 59 (2015) 152–158
Fig. 8 – Installed final restorations fabricated by either Scan/CAD/CAM technique ((A) occlusal view of maxillary ISP, (B) frontal view, (C) occlusal view of mandibular ISP) or conventional method ((D) occlusal view of maxillary ISP, (E) frontal view, (F) occlusal view of mandibular ISP).
Fig. 9 – Shape discrepancies calculated using the superposed images of scanned data of final and provisional restorations fabricated using the two different techniques. Total volume difference of convex/concave portions of final restorations relative to the provisional restorations was small by fabrication with Scan/CAD/CAM technique.
installation in the patient. Visual analysis of the final restorations indicated a more precise copy of the provisional restoration (Fig. 2) by the 3D Scan/CAD/CAM method. However, the patient could not sense differences between the shape and volume of the two final restorations. Therefore, in order to quantitatively assess and demonstrate the difference between the two techniques, we subsequently performed a computerbased 3D analysis of the final restorations.
3.2. In silico comparison of reproducibility between provisional and final restorations Two final restorations fabricated by different techniques and provisional restorations were scanned with a 3D scanner (Rexcan ARX, Solutionix, Korea) with accuracy 20 mm and images were superimposed using an imaging software (FreeForm, SensAble Technologies, USA). Discrepancies in
journal of prosthodontic research 59 (2015) 152–158
157
Fig. 10 – Shape discrepancies between final and provisional restorations displayed as color tones. Green area was dominant in images of Scan/CAD/CAM restorations, whereas a gray area was predominant in restorations fabricated by the conventional method.
the shape between final and provisional restoration were determined by the difference in total volume of the geometry of concave and convex portions of each final restoration relative to the provisional restoration using the FreeForm imaging software. This software can perform an automatic alignment and superimposition in one coordinate system of the two restorations, based on the best match of these selections. Best-fit alignment used 300 randomly selected points to get an initial operation [7]. Next, the sample size was automatically increased to 1500, and a further fine adjustment was performed to achieve the final alignment. Using this technique, images of final and provisional restorations were overlaid and difference in surface shape was measured and expressed in color tones using a different imaging software (EZ scan, Solutionix, Korea). Parts with no surface shape difference are shown in green, parts of 0.4 mm convex are expressed in red, and 0.3 mm concave parts are shown in blue. When the surface shape difference is more than the detection limit, these parts are displayed in gray. Color tones changes gradually in correspondence to the differences in surface shape.
4.
Effect or performance
First, final restorations fabricated either by the conventional or Scan/CAD/CAM method were successfully installed in the patient. Analysis of shape discrepancies between provisional and final restorations fabricated by both techniques revealed a more accurate copy of the details of the provisional restoration by Scan/CAD/CAM technique, with a total concave/convex volume discrepancy of 503.50 mm3 and 338.15 mm3 for maxillary and mandibular ISPs, respectively. On the other hand, total concave/convex volume discrepancy observed with the conventional method was markedly high (1106.84 mm3 and 771.23 mm3) for maxillary and mandibular ISPs, respectively (Fig. 9). Analysis of surface shape discrepancies by color tone showed a predominant green area in the images of restorations fabricated by Scan/CAD/CAM technique. However, gray
color was dominant in the final restorations fabricated by the conventional technique (Fig. 10).
5.
Conclusions
Within the limitation of this study, this Scan/CAD/CAM method showed the more precise and accurate than the conventional method at the time of transferring the provisional restorations to the final restorations. However, this method is only applicable in cases of fabrication of final restorations from a single material (e.g. zirconia, titanium) and still requires improvement in esthetics compared to final restorations fabricated with plural materials such as porcelain, hybrid ceramics and acrylic resin. In the future, it is necessary to create new digital techniques to fabricate Scan/ CAD/CAM restorations using plural materials. Additionally, we intend to create new digital techniques to accurately reproduce provisional restorations of conventional crowns/ bridges to final restorations, which is presently problematic due to lack of clear reference point in the working casts, which in turn, does not enable overlay of the scanned images.
Conflict of interest The authors declare that there are no conflicts of interest.
references
[1] Moscovitch MS, Saba S. The use of a provisional restoration in implant dentistry: a clinical report. Int J Oral Maxillofac Implants 1996;11:395–9. [2] Buskin R, Salinas TJ. Transferring emergence profile created from the provisional to the definitive restoration. Pract Periodontics Aesthet Dent 1998;10:1171–9. quiz 1180. [3] Breeding LC, Dixon DL. Transfer of gingival contours to a master cast. J Prosthet Dent 1996;75:341–3.
158
journal of prosthodontic research 59 (2015) 152–158
[4] Elian N, Tabourian G, Jalbout ZN, Classi A, Cho SC, Froum S, et al. Accurate transfer of peri-implant soft tissue emergence profile from the provisional crown to the final prosthesis using an emergence profile cast. J Esthet Restor Dent 2007;19:306–14. [5] Goodacre CJ, Garbacea A, Naylor WP, Daher T, Marchack CB, Lowry J. CAD/CAM fabricated complete dentures: concepts and clinical methods of obtaining required morphological data. J Prosthet Dent 2012;107:34–46.
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