Project Statement and Specifications

Transcription

1 Project Statement and Specifications Stimulating Bone Growth Using Piezoelectric Ultrasound Transducers on the Edentulous Jaw TEAM # 12 Team Members: Matthew Eschbach, Robert Sterling Nesbitt, Joseph Ouellette, Sarah Roberge Project for Shiva P. Kotha, PhD Client Contact Information: Shiva P. Kotha, PhD Assistant Professor of Biomechanics and Biomaterials University of Connecticut Department of Mechanical Engineering Arthur B. Bronwell Building 260 Glenbrook Road Storrs, CT 06269

2 Statement of Need In spite of advances in medical and dental technology, it is estimated the number of Americans needing dentures will rise to 37.9 million by the year Following the removal or loss of teeth, the stress that the teeth normally place on the jaw bones is absent. Dentures do not come in contact with the jaw bones like normal teeth, and so do not produce the same stress. Without this stress, bone density is reduced as the bones start to weaken and deteriorate. Therefore, a device is needed that will simulate the presence of teeth in the jaw bones so that the bone will maintain its strength. Introduction Bone loss in the jaw occurs due to a lack of mechanical forces from the teeth after they are lost or removed. When there are no mechanical forces present, the expression of a gene that stimulates bone formation is silenced 2. As a result, residual ridge resorption (RRR) occurs, which can lead to insignificant strength in the jaw so that dentures cannot be supported, and fracture risk increases 3. Under normal conditions, this gene is active and works to constantly maintain the bone. To prevent the gene from being silenced, a different force must be used to maintain the integrity of the bone. This will be done by using ultrasound strips placed in dentures or a mouthpiece, which are worn for a short time every day. To observe the effects of the ultrasound on the bone, in vivo testing must be performed on rodents. This will determine whether or not the strips function correctly. The animals will be put to sleep and their teeth will be removed. Tests will be performed to monitor the condition of the jaw bones over time. The strips will be implanted on the jaw of some of the animals to test the effects of the ultrasound and the other animals without ultrasound strips will be used as a control. The optimal signal to promote bone strength will be found through this testing. The ultrasound strips will be created using a Barium Titanate Powder, which will be compacted, sintered, and poled. The resulting strip will be secured into a mouthpiece that fits comfortably over the gums. A circuit will have to be designed to produce a specific electrical signal. The circuit will be connected to the ultrasound strips. The strips will then convert the electrical signal into an ultrasonic mechanical signal that is propagated into the gums of the 1 Douglass, Chester W. DMD, PhD, Annie Shih MS, DDS and Larry Ostry, DDS. Will there be a need for complete dentures in the United States in 2020? The Journal of Prosthetic Dentistry (2002): Nomura, Shintaro, Teruko Takano-Yamamoto. Molecular events caused by mechanical stress in bone. Matrix Biology. 19 (2000): Esa Klemetti DDS, PhD. A review of residual ridge resorption and bone density. The Journal of Prosthetic Dentistry (1996):

3 wearer. To prevent electrocution of or injury to the subject, the circuit and power supply will be housed in a case that is held on the outside of the mouth. Similar to an electronic tooth brush, the device will be battery powered. Successful testing on animals will provide a basis for the adaption of the human denture design. With this, bone loss in the jaw will be significantly reduced, which will decrease the chance of fracture and improve the quality of life for the patient. Limitations Economic - In order for the device to effectively help those individuals for whom it is intended, it must be affordable to the majority of the population possessing the need for it. - The cost of the product must still be greater than the cost of manufacturing, to ensure that the device is profitable. Environmental - The used parts must be capable of being disposed of easily and without harm to the environment. Sustainability - It must be durable. - The mouthpiece and power supply must maintain structural, mechanical and electrical integrity with daily use. - The mouthpiece must sustain daily cleaning. Manufacturability - The design of the device must be able to be reproduced by a manufacturer. - If the device contains replaceable parts, they should be readily available and easily replaced.

4 Ethical - The design of this project requires testing on animals. IACUC regulations must be strictly adhered to. - The animals need to be taken care of and kept comfortable, both out of respect for the animals and in the interest of the experiments. Health - There should be no adverse side effects to the user from using or operating the device. - The application of this device requires that part of it be inserted into the mouth. Therefore, a method of cleaning needs to be developed. This should not be complicated or time consuming. Safety - It must be nontoxic. - All electrical components must be fully shielded or insulated so that there is no risk of harm to the user. Social - The device must be as comfortable as possible for the wearer. - The majority of the wearers of the device will most likely be advanced in age. Therefore, all labels must be in large print. Buttons, switches, or knobs should be large and possibly brightly colored as well. - The device should be able to be used by individuals with disabilities. - It is important that the device is easy to operate and store. - The device should be as quiet and discreet as possible out of consideration for the users. Political - FDA regulations need to be abided by in the design of the experiment. Miscellaneous - There is only a limited time in which this project needs to be completed. The due date is April 10, This is the most rigid constraint.

5 Other Data The client, Dr. Shiva Kotha, is currently a professor of the Mechanical Engineering Department at the University of Connecticut. His research is aimed at the study of bone, namely the behavior of molecules and cells in response to mechanical loading. He has over 20 published papers in several highly regarded scientific journals. One aspect of this project involves computer modeling of the device. This is not only to obtain a schematic of the device itself, but to find what stresses will be applied to the jaw bones. This way a close approximation can be made to the actual stress that will be applied along the bone. In addition to the stress, the propagation of sound from the transducer to the bone can be tracked through these models. Questions 1) What kind of power supply will be utilized to power the device? How long will the supply last? 2) How will the circuits be designed? 3) What material will the mouthpiece be composed of? 4) How will power be safely delivered into the ultrasound strips inside of the mouth? 5) How will the device safely be tested on animals? 6) How will the strips be secured into the animals mouths? 7) How will the animals be fed in order to sustain life? 8) How will the bone density of the rat be quantified? 9) Who will be responsible for the care and upkeep of the animals? 10) Where will the animals be kept? 11) How will the teeth of the animals be removed? 12) How will the animal testing experiments be set up? 13) How much will the experiments and the equipment cost? 14) How will the strips be secured inside of the mouthpiece? 15) Will the strips need to be replaced? If so, how will this be accomplished? 16) What controls and functions will the device have? 17) What is the necessary application time for each use of the device? 18) How much voltage can safely be applied inside of the mouth? 19) How much voltage is needed to power the piezoelectric strips? 20) How will the mouthpiece be custom fit for each individual wearer? 21) How much will the mouthpiece weigh? 22) How much will the power supply weigh?

6 Technical Specifications Electrical Properties: Batter Power Supply: Charger Voltage: Ultrasound frequency: Output Duration: Application Frequency: Charging Time: 12V Rechargable 110V 60Hz 1-4MHz Adjustable 10 Minutes* 1-2 Times Daily No greater than 12 Hours *Spatial Average Temporal Average (SATA); Higher amplitude for shorter periods equals same energy Mechanical Properties: Mouthpiece: Dimensions: Custom: Mouthpiece designed to fit the client Handset: Dimensions: 20.0 x 5.0 x 5.0 cm (L x W x H) Weight: As light as possible Environmental: Mouthpiece Operating Temperature: Power Supply: 37 (Celsius) (Celsius)

7 Safety: Moisture resistant: Insulation: Mouthpiece, ultrasound strips and wires must be moisture resistant. Mouthpiece, plug and wires must be electrically insulated. Maintenance: Mouthpiece: Cleaning: Daily cleaning in denture cleanser Power Supply: Charging: Daily battery charging from outlet