STEREOLITHOGRAPHYAn advancement in Digital dentistry

Presented bySwetha PadaalaInternRagas Dental College, Chennai

Contents

• Introduction• History• Technology description• Clinical application in Dentistry• Advantages• Disadvantages• Cost of the procedure• Conclusion• Acknowledgement

Introduction• Stereolithography is a rapid

prototyping method, which allows the fabrication of anatomically accurate, 3-dimensional epoxy and acrylic resin models from various types of medical data.

• The device which performs stereolithography is called Stereolithography Apparatus(SLA)

History

Stereolithography was developed by Charles W. Hull in 1986.

The process was developed to overcome limitations of conventional CAM milling versus the inability to reproduce intricate anatomy of body structures.

Hull described a concentrated beam of ultraviolet light focused onto the surface of a vat filled with liquid photopolymer which cures it, thereby producing 3D model.

First working stereolithography system by Charles Hull

Schematic diagram of a Stereolithographic apparatus

Technology descriptionThe machine has four important parts:

• A tank filled with several gallons of liquid photopolymer.

• A perforated platform immersed in the tank.

• An ultraviolet laser

• A computer that drives the laser and the platform

The pattern to be modeled is traced using Images obtained from Computed Tomography or Magnetic Resonance Imaging or by using Optical Scanners.

After a pattern has been traced, the SLA's elevator platform descends by a single layer thickness, typically 0.05 mm to 0.15 mm (0.002" to 0.006").

Then, a resin-filled blade sweeps across the part cross section, re-coating it with fresh material. On this new liquid surface the subsequent layer pattern is traced, adhering to the previous layer. A complete 3 Dimensional part is formed by this process.

After building, parts are cleaned of excess resin by immersion in a chemical bath and then cured in an Ultraviolet oven.

Clinical applications in dentistry•Surgical Implant Guides

•Maxillofacial Reconstructive surgery, e.g. custom malar implant

•Preoperative planning of osseointegrated implant placement

•Preoperative planning for maxillary sinus augmentation procedures

•Diagnosis and treatment planning of numerous craniofacial clefts

•Can aid in the fabrication of custom devices, e.g. distraction osteogenesis device

•Future applications in bone matrix formation

•Custom model designs

Advantages

•Decreased operation/anesthesia time

•Decreased blood loss/surgical morbidity

•Allows for direct visualization of osseous structures

•Provides a valuable teaching aid

•Allows for presurgical planning/trial surgery

Disadvantages

•Time consuming depending on the size of the object

•Require support structures

•Expensive process

Costs of stereolithography

The procedure of stereolithography is expensive. The machines cost in excess of Rs.1.2 Crores. They have to be vented because of the fumes created by the solvents and polymer. The polymer is extremely expensive and can cost up to Rs. 36,000 per gallon. However a single stereolithographic model would cost a minimum of Rs.5000.

ConclusionDespite the relatively few disadvantages, stereolithography is preferred because of the following benefits

•The high degree of accuracy with which the models are obtained

•The relatively simple process

•The ability to produce objects of any shape and complexity

•Produces real models in 3 Dimensional structure

Acknowledgement

Dr. S.Shanmugam, Professor & HOD, Dept. of Oral Medicine and Radiology Ragas Dental College & Hospital

Thank You