- Email: [email protected]
Clinical guidelines for direct printed metal orthodontic appliances
Accepted Manuscript
Clinical guidelines for direct printed metal orthodontic appliances. Simon Graf PII: DOI: Reference:
S1073-8746(18)30068-9 https://doi.org/10.1053/j.sodo.2018.10.010 YSODO 556
To appear in:
Seminars in Orthodontics
Please cite this article as: Simon Graf , Clinical guidelines for direct printed metal orthodontic appliances., Seminars in Orthodontics (2018), doi: https://doi.org/10.1053/j.sodo.2018.10.010
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Clinical guidelines for direct printed metal orthodontic appliances. Simon Graf Simon Graf : Corresponding Author
Private Practice, Smile AG, Eichenweg 23,3123 Belp, Switzereland. E Mail id : [email protected]
CR IP T
+41786268897
Abstract
The aim of this article is to provide a comprehensive protocol for the clinical use of direct printed metal-based orthodontic appliances. This guideline tries to reveal the workflow after
AN US
complete digitalization in the orthodontic clinic, offering a step-by-step procedure and clinical applications of a directly printed metal appliance without the need for physical casts.
Introduction
M
The orthodontic profession needs to adapt, and embrace advancements, trying to
ED
implement and simplify digital technologies in the daily orthodontic workflow.1,2 By adapting to change, we are today comparable to a situation in history, when travelling by plane became more regular, some adaptive sail-makers started to deliver their canvas to the
PT
plane-builders as a cover for the wing-frame-work, instead of disappearing with the vanishing sailboats. I do not advocate blind adoption, but a thorough evaluation of all that
CE
there is to offer. Of course there are always new technologies that will fail, or lead to a deadend. The easiest way is to evaluate if there’s a benefit in a new available technology for an
AC
orthodontist, is to ask, “if the patient can profit from it? Not just the orthodontist!” In an era of instant gratification, people desire the needs to go faster nowadays, and having a look at the success of companies, delivering a new smile for the patients to their homes, obviously there’s a high demand for reducing the chair-side time in the orthodontic office. The process demonstrated in this article is an innovation that can benefit chair-side efficacy and open new possibilities to direct metal printing in orthodontics, an area that is generating a lot of interest.3
ACCEPTED MANUSCRIPT The intraoral scanner used in this procedure was the Trios 2 from 3Shape(Copenhagen, Denmark). Of course, the STL-file (surface tessellation language, three-dimensional noncolored data) can be produced with a lab-scanner or CT, or from the impression-tray /gypsum-cast directly. The STL-file from the jaw needs to be imported in software where it’s possible to manipulate three-dimensional files. In this virtual space, the orthodontic appliance can be designed. First the tooth surface needs to be defined, then the distance
CR IP T
between tooth surface and appliance should be locked, so it will be always the same. Now it’s possible to design the bonding site of the appliance. It can have the same shape as a classic molar band, just not passing through the contact-points to the neighboring tooth, or like a C-clasp shape from partial prosthodontics or just a supportive stick following the shape of the tooth. From that point there are no limits for the appliance design. Starting from a
AN US
space-maintainer, a rapid-palatal expander, a trans-palatal arch, a lingual arch, to a Herbstappliance or a mandibular advancement (MARA) appliance is possible. 4
M
Step-by-step appliance fabrication
ED
Let’s follow step by step the build up from a rapid-palatal-expansion device. The molar bands were designed with a 0.7mm thickness around the molars with a distance of 0.05mm to the tooth surface with the biggest bonding surface possible, to enhance the
PT
retention on the tooth. The molar bands were extended till the first premolar in the same shape of the bands, covering the palatal surface from the gingival border till the cusps. The
CE
bonding site should be planned according to the bonding procedure of the orthodontist. If there’s a composite-based bonding material used, the surface can be designed more filigran,
AC
if the user want’s to go for cementum, the surface should be expanded as big as possible. Then the connectors to the expansion screw (Snap-lock expander, Forestadent, Germany) are designed from the molar and the first premolar as a round stick. The specifications of the connector was chosen in this case was a round shape with a 1.2mm thickness. The expansion screw is virtually added from a digital library and the connectors are designed along the biggest connecting site of the expansion screw. Likewise every active preformed element can be stored in the library and added after the printing process. For debonding, it is useful to add some small buttons to the outside of the appliance, so it is
ACCEPTED MANUSCRIPT easier to grab the appliance with the debonding plier. The software used in this case was the appliance designer from 3Shape(Copenhagen, Denmark), but every open source software like Exocad or Mesh-mixer, to name a few, can be used as well. The advantage of a dentalfocused software is, that there are some pre-settings available, making it easier to design the appliance. After the orthodontist confirms the design, the appliance is sent digitally to the laser-melting
CR IP T
(three dimensional metal printing) machine (Concept Laser, Hoffmann Innovation Group, Lichtenfels,Germany). The appliance is printed with Remanium® Star CL (Dentaurum,
Ispringen, Germany), a metal alloy powder consisting of Cobalt, Chromium, Tungsten and Selenium. As an explanation of the printing process, it’s possible to imagine a round ball. So the machine spreads the metal powder in a thin first layer, then a laser beam is melting the
AN US
powder in one spot, soldering the powder together. Then the machine distributes a second powder layer, and the laser beam is now soldering a small circle, following the shape of the ball. This happens, layer by layer.
After the sintering process, the appliance has to cool down, the unsoldered powder needs to be cleaned away and the supporting sticks have to be taken off. These sticks are needed, as
M
the appliance would bend due to it’s own weight during the cooling period.
ED
The rough surface needs to be polished either by hand or with a polishing machine. Only the bonding site can remain unpolished, or sandblasted in the end.
CE
prepared site.
PT
Active elements, like the expansion-screw in this example can be laser soldered now to the
Clinical Procedure
AC
The patient has to be prepared the same way, as it would be for any fixed appliance. In this case the Nola-Dry-Filed is used to keep the teeth dry. Etching-gel(3M Unitek) was used to etch the teeth, after rinsing & air drying, Scotch-bond Universal(3M) was added to the etched tooth surface, air-dried and light cured(following the manufacturers recomendation). On the appliance, the Scotch-bond Universal was used on the sandblasted bonding site, airdried and light-cured. Afterwards a thin layer of Transbond XT(3M) is is spread over the complete bonding surface, gently adapted with an instrument. The appliance is then inserted in the mouth, pressed gently to the teeth. All the bondingmaterial excesses can be removed before light curing. After the cleaning, the bonding-
ACCEPTED MANUSCRIPT material needs to be light-cured, further. Now the Nola can be removed, and the patient can rinse, followed by the instructions needed for his appliance.
Final thoughts…
CR IP T
Rapid prototyping, the additive way to produce orthodontic appliances, will replace sooner or later the classic production systems. Right now, there aren’t so many different printable metals available, but for example with a CoCr-powder-alloy, the properties can be changed already with adding more or less oxygen during the sintering process, to change the stiffness of the final product. The author is right now experimenting with Titanium-printed appliances
AN US
with properties other than CoCr. Also, removable appliances like a twin-block or a upper retention plate, can now be printed directly with biocompatible class IIa materials directly, without having to print models for fabrication, thereby eliminating a step. Especially in terms of aligners, the development of direct printable materials should be
M
further developed from an environmental hazard perspective, as thousands of tooth-arches
for disposal afterwards.
PT
References : GRAF
ED
are printed daily in many orthodontic clinics and laboratories, without a stipulated regimen
CE
1) Vaid NR. Up in the Air: Orthodontic technology unplugged!. APOS Trends Orthod 2017;7:1-5
AC
2) Christensen LR. Digital workflows in contemporary orthodontics. APOS Trends Orthod 2017;7:12-8
3) Graf.S.,Cornelis M.A.,Gamerio G.H.,Cattaneo P.M.,Computer-aided design and manufacture of hyrax devices: Can we really go digital? : Am J Orthod –Dec 2017, Volume 152, Issue 6, Pages 870–874.
4) Graf S. Direct printed metal devices - The next level of computer-aided design and computer-aided manufacturing applications in the orthodontic care. APOS Trends Orthod 2017;7:253-9
ACCEPTED MANUSCRIPT Seminars in orthodontics A clinical guideline to direct printed metallic orthodontic appliances Simon Graf
AC
CE
PT
ED
M
01.Anterior view before and after Expansion
AN US
CR IP T
Picture content:
02.Occlusal view Before and after Hyrax
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
03. Design of the bands & bonding-sites with positioning of the expansion screw
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
AN US
CR IP T
04. Lasermelting in progress (Courtesy to Conceptlaser)
ACCEPTED MANUSCRIPT
AN US
CR IP T
05. Hyrax close-up after lasermelting and sintering
AC
CE
PT
ED
M
06. Occlusion anterior before insertion and expansion with the Hyrax appliance
07. Occlusion before expansion and insertion of the Hyrax appliance
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
08. Insertion of Hyrax, with Transbond XT and Nola Dry-field-system
09. Pressure around the molarbands for a perfect fit
AC
CE
PT
ED
M
10. Cleaning of the Transbond XT excess
AN US
CR IP T
ACCEPTED MANUSCRIPT
11. Cleaning of the Transbond XT excess II
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
12. Light-Curing
13. Final cleaning of the Transbond excess with the ortho-scaler
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
14. Occlusion after insertion of the Hyrax appliance
15. Occlusion after expansion
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
16. Occlusion anterior After expansion
17. Hyrax design on decidous teeth only
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
18. Hyrax on decidous teeth only
19. Lingual arch with open molar-band design for improved cleaning
Clinical guidelines for direct printed metal orthodontic appliances. Simon Graf PII: DOI: Reference:
S1073-8746(18)30068-9 https://doi.org/10.1053/j.sodo.2018.10.010 YSODO 556
To appear in:
Seminars in Orthodontics
Please cite this article as: Simon Graf , Clinical guidelines for direct printed metal orthodontic appliances., Seminars in Orthodontics (2018), doi: https://doi.org/10.1053/j.sodo.2018.10.010
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Clinical guidelines for direct printed metal orthodontic appliances. Simon Graf Simon Graf : Corresponding Author
Private Practice, Smile AG, Eichenweg 23,3123 Belp, Switzereland. E Mail id : [email protected]
CR IP T
+41786268897
Abstract
The aim of this article is to provide a comprehensive protocol for the clinical use of direct printed metal-based orthodontic appliances. This guideline tries to reveal the workflow after
AN US
complete digitalization in the orthodontic clinic, offering a step-by-step procedure and clinical applications of a directly printed metal appliance without the need for physical casts.
Introduction
M
The orthodontic profession needs to adapt, and embrace advancements, trying to
ED
implement and simplify digital technologies in the daily orthodontic workflow.1,2 By adapting to change, we are today comparable to a situation in history, when travelling by plane became more regular, some adaptive sail-makers started to deliver their canvas to the
PT
plane-builders as a cover for the wing-frame-work, instead of disappearing with the vanishing sailboats. I do not advocate blind adoption, but a thorough evaluation of all that
CE
there is to offer. Of course there are always new technologies that will fail, or lead to a deadend. The easiest way is to evaluate if there’s a benefit in a new available technology for an
AC
orthodontist, is to ask, “if the patient can profit from it? Not just the orthodontist!” In an era of instant gratification, people desire the needs to go faster nowadays, and having a look at the success of companies, delivering a new smile for the patients to their homes, obviously there’s a high demand for reducing the chair-side time in the orthodontic office. The process demonstrated in this article is an innovation that can benefit chair-side efficacy and open new possibilities to direct metal printing in orthodontics, an area that is generating a lot of interest.3
ACCEPTED MANUSCRIPT The intraoral scanner used in this procedure was the Trios 2 from 3Shape(Copenhagen, Denmark). Of course, the STL-file (surface tessellation language, three-dimensional noncolored data) can be produced with a lab-scanner or CT, or from the impression-tray /gypsum-cast directly. The STL-file from the jaw needs to be imported in software where it’s possible to manipulate three-dimensional files. In this virtual space, the orthodontic appliance can be designed. First the tooth surface needs to be defined, then the distance
CR IP T
between tooth surface and appliance should be locked, so it will be always the same. Now it’s possible to design the bonding site of the appliance. It can have the same shape as a classic molar band, just not passing through the contact-points to the neighboring tooth, or like a C-clasp shape from partial prosthodontics or just a supportive stick following the shape of the tooth. From that point there are no limits for the appliance design. Starting from a
AN US
space-maintainer, a rapid-palatal expander, a trans-palatal arch, a lingual arch, to a Herbstappliance or a mandibular advancement (MARA) appliance is possible. 4
M
Step-by-step appliance fabrication
ED
Let’s follow step by step the build up from a rapid-palatal-expansion device. The molar bands were designed with a 0.7mm thickness around the molars with a distance of 0.05mm to the tooth surface with the biggest bonding surface possible, to enhance the
PT
retention on the tooth. The molar bands were extended till the first premolar in the same shape of the bands, covering the palatal surface from the gingival border till the cusps. The
CE
bonding site should be planned according to the bonding procedure of the orthodontist. If there’s a composite-based bonding material used, the surface can be designed more filigran,
AC
if the user want’s to go for cementum, the surface should be expanded as big as possible. Then the connectors to the expansion screw (Snap-lock expander, Forestadent, Germany) are designed from the molar and the first premolar as a round stick. The specifications of the connector was chosen in this case was a round shape with a 1.2mm thickness. The expansion screw is virtually added from a digital library and the connectors are designed along the biggest connecting site of the expansion screw. Likewise every active preformed element can be stored in the library and added after the printing process. For debonding, it is useful to add some small buttons to the outside of the appliance, so it is
ACCEPTED MANUSCRIPT easier to grab the appliance with the debonding plier. The software used in this case was the appliance designer from 3Shape(Copenhagen, Denmark), but every open source software like Exocad or Mesh-mixer, to name a few, can be used as well. The advantage of a dentalfocused software is, that there are some pre-settings available, making it easier to design the appliance. After the orthodontist confirms the design, the appliance is sent digitally to the laser-melting
CR IP T
(three dimensional metal printing) machine (Concept Laser, Hoffmann Innovation Group, Lichtenfels,Germany). The appliance is printed with Remanium® Star CL (Dentaurum,
Ispringen, Germany), a metal alloy powder consisting of Cobalt, Chromium, Tungsten and Selenium. As an explanation of the printing process, it’s possible to imagine a round ball. So the machine spreads the metal powder in a thin first layer, then a laser beam is melting the
AN US
powder in one spot, soldering the powder together. Then the machine distributes a second powder layer, and the laser beam is now soldering a small circle, following the shape of the ball. This happens, layer by layer.
After the sintering process, the appliance has to cool down, the unsoldered powder needs to be cleaned away and the supporting sticks have to be taken off. These sticks are needed, as
M
the appliance would bend due to it’s own weight during the cooling period.
ED
The rough surface needs to be polished either by hand or with a polishing machine. Only the bonding site can remain unpolished, or sandblasted in the end.
CE
prepared site.
PT
Active elements, like the expansion-screw in this example can be laser soldered now to the
Clinical Procedure
AC
The patient has to be prepared the same way, as it would be for any fixed appliance. In this case the Nola-Dry-Filed is used to keep the teeth dry. Etching-gel(3M Unitek) was used to etch the teeth, after rinsing & air drying, Scotch-bond Universal(3M) was added to the etched tooth surface, air-dried and light cured(following the manufacturers recomendation). On the appliance, the Scotch-bond Universal was used on the sandblasted bonding site, airdried and light-cured. Afterwards a thin layer of Transbond XT(3M) is is spread over the complete bonding surface, gently adapted with an instrument. The appliance is then inserted in the mouth, pressed gently to the teeth. All the bondingmaterial excesses can be removed before light curing. After the cleaning, the bonding-
ACCEPTED MANUSCRIPT material needs to be light-cured, further. Now the Nola can be removed, and the patient can rinse, followed by the instructions needed for his appliance.
Final thoughts…
CR IP T
Rapid prototyping, the additive way to produce orthodontic appliances, will replace sooner or later the classic production systems. Right now, there aren’t so many different printable metals available, but for example with a CoCr-powder-alloy, the properties can be changed already with adding more or less oxygen during the sintering process, to change the stiffness of the final product. The author is right now experimenting with Titanium-printed appliances
AN US
with properties other than CoCr. Also, removable appliances like a twin-block or a upper retention plate, can now be printed directly with biocompatible class IIa materials directly, without having to print models for fabrication, thereby eliminating a step. Especially in terms of aligners, the development of direct printable materials should be
M
further developed from an environmental hazard perspective, as thousands of tooth-arches
for disposal afterwards.
PT
References : GRAF
ED
are printed daily in many orthodontic clinics and laboratories, without a stipulated regimen
CE
1) Vaid NR. Up in the Air: Orthodontic technology unplugged!. APOS Trends Orthod 2017;7:1-5
AC
2) Christensen LR. Digital workflows in contemporary orthodontics. APOS Trends Orthod 2017;7:12-8
3) Graf.S.,Cornelis M.A.,Gamerio G.H.,Cattaneo P.M.,Computer-aided design and manufacture of hyrax devices: Can we really go digital? : Am J Orthod –Dec 2017, Volume 152, Issue 6, Pages 870–874.
4) Graf S. Direct printed metal devices - The next level of computer-aided design and computer-aided manufacturing applications in the orthodontic care. APOS Trends Orthod 2017;7:253-9
ACCEPTED MANUSCRIPT Seminars in orthodontics A clinical guideline to direct printed metallic orthodontic appliances Simon Graf
AC
CE
PT
ED
M
01.Anterior view before and after Expansion
AN US
CR IP T
Picture content:
02.Occlusal view Before and after Hyrax
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
03. Design of the bands & bonding-sites with positioning of the expansion screw
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
AN US
CR IP T
04. Lasermelting in progress (Courtesy to Conceptlaser)
ACCEPTED MANUSCRIPT
AN US
CR IP T
05. Hyrax close-up after lasermelting and sintering
AC
CE
PT
ED
M
06. Occlusion anterior before insertion and expansion with the Hyrax appliance
07. Occlusion before expansion and insertion of the Hyrax appliance
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
08. Insertion of Hyrax, with Transbond XT and Nola Dry-field-system
09. Pressure around the molarbands for a perfect fit
AC
CE
PT
ED
M
10. Cleaning of the Transbond XT excess
AN US
CR IP T
ACCEPTED MANUSCRIPT
11. Cleaning of the Transbond XT excess II
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
12. Light-Curing
13. Final cleaning of the Transbond excess with the ortho-scaler
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
14. Occlusion after insertion of the Hyrax appliance
15. Occlusion after expansion
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
16. Occlusion anterior After expansion
17. Hyrax design on decidous teeth only
AN US
CR IP T
ACCEPTED MANUSCRIPT
AC
CE
PT
ED
M
18. Hyrax on decidous teeth only
19. Lingual arch with open molar-band design for improved cleaning