- Email: [email protected]
Digital splint fabrication
because the esthetic effects of microabrasion can be observed after a single session.
Clinical Significance.—Sometimes the psychological benefits available from improved esthetics are lost to the more exotic aspects of a patient’s history. Our patients’ lives and feelings of self-worth can be significantly improved by this simple, yet often overlooked, procedure.
Fig 5.—The patient’s teeth 24 months after microabrasion treatment. (Courtesy of de Macedo AF, Tomazela-Herndl S, Correˆa MSNP, et al: Enamel microabrasion in an individual with Cohen syndrome. Spec Care Dentist 28:116-119, 2008.)
de Macedo AF, Tomazela-Herndl S, Correˆa MSNP, et al: Enamel microabrasion in an individual with Cohen syndrome. Spec Care Dentist 28:116-119, 2008 Reprints available from AF de Macedo; e-mail: adriana.macedo@ unicsul.br
Temporomandibular Disorders Digital splint fabrication Background.—Occlusal splints are usually fabricated using manual articulation and trimming methods, which guarantees that the same splint will never be made more than once, even by the same technician. Because each laboratory has its own way of articulating unmounted casts, differences occur between the various sources. The casts can be visually oriented or the upper or lower cast can be placed against the flat surface of a mounting jig. The occlusal plane is then defined by the three highest points on the dentition, tilting the orientation of the arches significantly. The orientation of the cast on the mounting jig can also change the orientation of the hinge relative to the cast and the axis incisal distance. Similarly, manual trimming can cause interlaboratory differences. If residual tooth impressions are left on the final contact surface, which is a common occurrence, these tend to lock patients in place and inhibit free movement, which is needed to deprogram the muscles. A digitally based manufacturing approach offers better consistency, quantitative control, and speed of fabrication. The natural biologic variations are managed using flexible design software. The system for producing splints is similar to that for other dental computer-aided design/computer-aided manufacturing (CAD/CAM) systems. The first computer-based design and production of flat-plane splints and splints with guidance ramps was documented. Methods.—Stone casts were laser scanned in six passes 60 apart that were then combined into a single object. Because the scans are calibrated to define the casts in relation to the mounting plate, they end up positioned in the
computer just as they would be on a physical articulator. Customized software was used to articulate and design flat-plane and full-coverage splints with guidance ramps. In the actual production of a splint, acrylic placed over the splint cast is machined down. The underlying tooth anatomy of the splint does not require machining; it is reproduced by the acrylic. The size of the files is significantly reduced and the machining operation considerably simplified. Areas with contact points are machined completely down to the designed surface (Figs 4 and 5). Because the force of the machining is considerable, stone is used instead of plaster for the casts. Standard wire clasping inside appliances are accommodated by adjusting tool paths using the CAM software. No further finishing is required after the contact surface is machined to an accuracy of less than 10 mm. Discussion.—Smoothness of the contact surface is an important component of digital splints. The digitally produced splints do not have the residual indexing impressions left in the manual process and allow the teeth to more freely move over the splint surface. The fit of the appliance before equilibration must demonstrate good seating. Because clinical contacts appear as fine markings or points rather than larger marks made with articulating paper, the equilibration process is simplified. The location of the initial contacts anteroposteriorly is determined by the arc of closure. Currently, cases sent to a laboratory for manual fabrication are not mounted, have no facebow recording, and have interocclusal records that vary in thickness and type. Although
Volume 54
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2009
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Fig 5.—Screen shot of CAM software. Three sets of nonuniform rational B-spline patches on the contact surface have been selected for finer machining. The complete machining tool paths for a 1/8-in diameter tool are shown. (Courtesy of Lauren M, McIntyre F: A new computer-assisted method for design and fabrication of occlusal splints. Am J Orthod Dentofacial Orthop 133:S130-S135, 2008.)
a true hinge axis recording with an accurate centric-relation record yields the most accurate representation of the arc of closure, this practice is not standard in most dental offices. Better ways to demonstrate the arc of closure are therefore being developed for the digital system. The digital process overall mirrors conventional CAD/ CAM systems, including scanning, CAD design, and machining. The results are more precise and consistent with respect to articulation, appliance design, and production.
Fig 4.—Flat-plane maxillary arch splint. A, Contact points from mandibular arch, B, with anterior and canine guidance ramps. The splint has a 2-mm shelf extending lingually from the anterior contact points. The canine and anterior ramps blend smoothly into each other. C, Lingual view shows contact points and canine and anterior ramps. (Courtesy of Lauren M, McIntyre F: A new computer-assisted method for design and fabrication of occlusal splints. Am J Orthod Dentofacial Orthop 133:S130-S135, 2008.)
26
Dental Abstracts
Clinical Significance.—Freedom from occlusal interferences during mandibular movements is essential for successful splint therapy. CAD/CAM technology for splint production minimizes the variability inherent with traditional fabrication methods. This technology is recommended when using occlusal splints.
Lauren M, McIntyre F: A new computer-assisted method for design and fabrication of occlusal splints. Am J Orthod Dentofacial Orthop 133:S130-S135, 2008 Reprints available from M Lauren, Director of Research, Great Lakes Orthodontics, 200 Cooper Ave, Tonawanda, NY 14150; e-mail: [email protected]
Clinical Significance.—Sometimes the psychological benefits available from improved esthetics are lost to the more exotic aspects of a patient’s history. Our patients’ lives and feelings of self-worth can be significantly improved by this simple, yet often overlooked, procedure.
Fig 5.—The patient’s teeth 24 months after microabrasion treatment. (Courtesy of de Macedo AF, Tomazela-Herndl S, Correˆa MSNP, et al: Enamel microabrasion in an individual with Cohen syndrome. Spec Care Dentist 28:116-119, 2008.)
de Macedo AF, Tomazela-Herndl S, Correˆa MSNP, et al: Enamel microabrasion in an individual with Cohen syndrome. Spec Care Dentist 28:116-119, 2008 Reprints available from AF de Macedo; e-mail: adriana.macedo@ unicsul.br
Temporomandibular Disorders Digital splint fabrication Background.—Occlusal splints are usually fabricated using manual articulation and trimming methods, which guarantees that the same splint will never be made more than once, even by the same technician. Because each laboratory has its own way of articulating unmounted casts, differences occur between the various sources. The casts can be visually oriented or the upper or lower cast can be placed against the flat surface of a mounting jig. The occlusal plane is then defined by the three highest points on the dentition, tilting the orientation of the arches significantly. The orientation of the cast on the mounting jig can also change the orientation of the hinge relative to the cast and the axis incisal distance. Similarly, manual trimming can cause interlaboratory differences. If residual tooth impressions are left on the final contact surface, which is a common occurrence, these tend to lock patients in place and inhibit free movement, which is needed to deprogram the muscles. A digitally based manufacturing approach offers better consistency, quantitative control, and speed of fabrication. The natural biologic variations are managed using flexible design software. The system for producing splints is similar to that for other dental computer-aided design/computer-aided manufacturing (CAD/CAM) systems. The first computer-based design and production of flat-plane splints and splints with guidance ramps was documented. Methods.—Stone casts were laser scanned in six passes 60 apart that were then combined into a single object. Because the scans are calibrated to define the casts in relation to the mounting plate, they end up positioned in the
computer just as they would be on a physical articulator. Customized software was used to articulate and design flat-plane and full-coverage splints with guidance ramps. In the actual production of a splint, acrylic placed over the splint cast is machined down. The underlying tooth anatomy of the splint does not require machining; it is reproduced by the acrylic. The size of the files is significantly reduced and the machining operation considerably simplified. Areas with contact points are machined completely down to the designed surface (Figs 4 and 5). Because the force of the machining is considerable, stone is used instead of plaster for the casts. Standard wire clasping inside appliances are accommodated by adjusting tool paths using the CAM software. No further finishing is required after the contact surface is machined to an accuracy of less than 10 mm. Discussion.—Smoothness of the contact surface is an important component of digital splints. The digitally produced splints do not have the residual indexing impressions left in the manual process and allow the teeth to more freely move over the splint surface. The fit of the appliance before equilibration must demonstrate good seating. Because clinical contacts appear as fine markings or points rather than larger marks made with articulating paper, the equilibration process is simplified. The location of the initial contacts anteroposteriorly is determined by the arc of closure. Currently, cases sent to a laboratory for manual fabrication are not mounted, have no facebow recording, and have interocclusal records that vary in thickness and type. Although
Volume 54
Issue 1
2009
25
Fig 5.—Screen shot of CAM software. Three sets of nonuniform rational B-spline patches on the contact surface have been selected for finer machining. The complete machining tool paths for a 1/8-in diameter tool are shown. (Courtesy of Lauren M, McIntyre F: A new computer-assisted method for design and fabrication of occlusal splints. Am J Orthod Dentofacial Orthop 133:S130-S135, 2008.)
a true hinge axis recording with an accurate centric-relation record yields the most accurate representation of the arc of closure, this practice is not standard in most dental offices. Better ways to demonstrate the arc of closure are therefore being developed for the digital system. The digital process overall mirrors conventional CAD/ CAM systems, including scanning, CAD design, and machining. The results are more precise and consistent with respect to articulation, appliance design, and production.
Fig 4.—Flat-plane maxillary arch splint. A, Contact points from mandibular arch, B, with anterior and canine guidance ramps. The splint has a 2-mm shelf extending lingually from the anterior contact points. The canine and anterior ramps blend smoothly into each other. C, Lingual view shows contact points and canine and anterior ramps. (Courtesy of Lauren M, McIntyre F: A new computer-assisted method for design and fabrication of occlusal splints. Am J Orthod Dentofacial Orthop 133:S130-S135, 2008.)
26
Dental Abstracts
Clinical Significance.—Freedom from occlusal interferences during mandibular movements is essential for successful splint therapy. CAD/CAM technology for splint production minimizes the variability inherent with traditional fabrication methods. This technology is recommended when using occlusal splints.
Lauren M, McIntyre F: A new computer-assisted method for design and fabrication of occlusal splints. Am J Orthod Dentofacial Orthop 133:S130-S135, 2008 Reprints available from M Lauren, Director of Research, Great Lakes Orthodontics, 200 Cooper Ave, Tonawanda, NY 14150; e-mail: [email protected]