trans dental - functional specifications

School of Engineering Science

Burnaby, BC, V5A 1S6

October 15, 2007 Dr. Andrew Rawicz School of Engineering Science Simon Fraser University Burnaby, British Columbia V5A 1S6 Re: ENSC 440 Project Functional Specification for Trans Dental Monitoring Solution. Dear Dr. Rawicz, Please find attached the Functional Specification for Trans Dental Monitoring Solution document. We, at Trans Dental Technologies, are in the process of designing and building a device that can be used by the dentists to monitor the anesthesia status of a numbed tooth at the beginning and during a dental operation. This will alarm the dentist to stop working or reapply anesthesia when the numbing effect is wearing off. This document will outline a set of requirements that are to be considered when designing and building the device. These requirements will not only include the technical and physical aspects but also the consideration of usability and human interaction with the device. This document will be used as a guide throughout different designing and building stages of the project. Innovative Dental Technologies consists of four enthusiastic and innovative final-year engineering science students: Isabella Taba, Petar Ivaz, Bahman Sotoodian and Mohammadali Khorasani, each of whom contribute to the diversity of the group while sharing the same interest of wanting to make a difference. Please feel free to contact me at [email protected] with any questions or concerns regarding the functional specification. Sincerely,

Mohammadali Khorasani Chief Executive Officer Trans Dental Technologies Enclosure: Functional Specification for Trans Dental Monitoring Solution

Functional Specification for

TRANS DENTAL MONITORING SOLUTION

Project Team Petar Ivaz Mohammadali Khorasani Bahman Sotoodian Isabella Taba

Contact Person Mohammadali Khorasani [email protected]

Submitted to Dr. Andrew Rawicz – ENSC 440 Mike Sjoerdsma – ENSC 305

Issued date October 15, 2007

Revision 1.0

Functional Specifications for the Trans Dental Monitoring Solution

Copyright 2007, Trans Dental Technologies ii

Executive Summary The thought of a drill digging into a tooth is enough to send a chill down anyone’s spine. The vast majority of us will be subject to it at some point in our lives. Anaesthesia is a very powerful numbing tool and when used properly, completely shuts down the local nerves. The downside is that the effectiveness of the anaesthesia has more to do with the dentist’s skill and experience, rather than the product itself. When administering anaesthesia a dentist has to rely on patient feedback. Most patients are aware when the numbing has taken effect, and the dentist can proceed with the surgery. There is a significant minority of people who cannot feel if their teeth have been numbed properly. On one end of the spectrum are people with immense fear of needles, and on the other, people with immense fear of pain. The former suffers from too little anesthesia, while the latter from too much. Our device, TDMS (Trans Dental Monitoring Solution), will assist the dentist in determining when the proper level of anaesthesia has been administered. It will also serve to monitor the effects of anaesthesia during a dental procedure. When a specific amount of current is applied to a tooth, the patient experiences a touch sensation. It is important to note that this sensation is painless. This document outlines how we intend to implement our product. When a dentist works on a patients tooth, they use a clamp around it. This clamp isolates the tooth from the rest of the mouth, and forms a very tight seal. The electrical contact point between the tooth and TDMS is on the inside of the clamp. The inward pressure produced by the clamp will push the positive end of our circuit into the tooth, isolating it from water. The ground will be attached to the opposite side of the mouth by a simple hook. The patient will feel a touch sensation every 2 seconds. Touch sensation is very subjective, and each patient will have a different current threshold at which they feel something. Before applying the anaesthesia, the dentist will apply TMDS to the tooth and increase the current applied. Once the patient notes they can feel a distinct touch sensation, the dentist will begin to apply the anaesthetic. Our device will stay on the tooth and apply the pre-determined current. Once the patient has stopped feeling the rhythmic pulses, they will alert the dentist. The device is very small, and only a small wire is applied to the area. This is important, as we want to keep the area around the tooth non-cluttered. Trans Dental has recently completed the research phase, and has fully transitioned into the development stage. We aim to have a full prototype developed by mid December of 2007.


Copyright 2007, Trans Dental Technologies iii

Table of Contents

1 Introduction _______________________________________________________ 1

1.1 Scope _______________________________________________________________ 1

1.2 Intended Audience ___________________________________________________ 1

2 System Requirements ________________________________________________ 2

2.1 System Overview _____________________________________________________ 3

2.2 Electrical Requirement ________________________________________________ 4

2.3 Mechanical Requirements _____________________________________________ 4

2.4 Environmental Requirements __________________________________________ 5

2.5 Physical Requirements ________________________________________________ 5

2.6 Standards ___________________________________________________________ 5

2.7 Safety Requirements __________________________________________________ 6

2.8 Performance Requirements ____________________________________________ 6

2.9 Reliability and Durability ______________________________________________ 7

3 Clamp ____________________________________________________________ 7

3.1 General Requirements ________________________________________________ 8

3.2 Physical Requirements ________________________________________________ 9

4 User Interface Unit ________________________________________________ 10

4.1 General Requirements: _______________________________________________ 10

4.2 Usability and Physical Requirements ___________________________________ 10

5 System Test Plan __________________________________________________ 11

6 User Documentation _______________________________________________ 12

7 Conclusion _______________________________________________________ 12

8 References _______________________________________________________ 13


Copyright 2007, Trans Dental Technologies iv

List of Figures Figure 2-1 General Overview of TDMS ___________________________________________ 2 Figure 2-2 - The High-Level Functional Block Diagram ________________________________ 3 Figure 3-1 – Dental Clamp ___________________________________________________ 7 Figure 3-2 – Simple Overview of TDMS __________________________________________ 8 Figure 4-1 – User Interface ___________________________________________________ 10

List of Tables Table 3-1 Spring Lengths for Variuos Clamps ______________________________________ 9


Copyright 2007, Trans Dental Technologies

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1 Introduction The Trans Dental Monitoring Solution (TDMS) is a device that can be placed on the tooth and monitors the activity of the tooth nerve. It is proposed that a tooth that is anaesthetized will show no nerve activity. Furthermore, a tooth that is “awake” or “waking up” will show nerve activity and the dentist can administer anaesthetic to achieve profound anaesthesia. TDMS will send consecutive pulses at predefined intervals and amplitude which is below the patient perception threshold. As soon as the amount of the anaesthetic drops the patient will feel the signal and gives the feedback to the dentist. The requirements for TDMS are described in this functional specification.

1.1 Scope

This document describes the functional requirements that must be met by a functioning TDMS. These set of requirements fully describe the proof-of-concept device and partially describes the production device. The listed requirements will drive the design of the TDMS device and will be traceable in future design documents.

1.2 Intended Audience

The functional specification is intended for use by all members of Trance Dental Technologies. TDT will use this document as a guideline in building the product. The project manager will refer to the functional specifications and requirements as a concrete measure of progress throughout the development phase. Design engineers will use this document as an overall design goal and test engineers will used this document in assessing the similarity of function in actual system with the functionality described in this document.



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2 System Requirements

The overall requirements for Trans Dental Monitoring Solution (TDMS) have been described in the following section. The general implementation of our product is seen in Figure 2-1.

Figure 2-1 General Overview of TDMS



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2.1 System Overview

The high level system of TDMS has been depicted in Figure 2-2. Input Output

Figure 2-2 - The High-Level Functional Block Diagram

The most important part of system is the preliminary operation which will be performed by the dentist. The dentist will mount the clamp on the patients’ tooth and provide a constant current with specific increasing step size to tooth. The current which trigger the patients’ perception will be used as input data for TDMS. The incrementing steps should be very small in range of 0.3 µA to assure that the dentist would not pass the pain threshold of patient. The TDMS then will determine the appropriate frequency and amplitude of its square signals. The output signals will be transferred to the patient’s tooth through an electrode. The electrode will be properly adjusted by the spring which is located on the clamp. When the clamp is tightened around the tooth, it will compress the spring and consequently force the electrode to contact the tooth. When the dentist injects the anaesthesia, the TDMS continues sending its signals. The dentists have to wait until the patient would not perceive anything. This will reduce the unnecessary long duration that dentists have to wait before starting their operations. It also will reduce any misjudgements that patients would do regarding the numbing of their tooth. It has been reported some cases where patients wrongly informed the dentists that their tooth is numb and during the operation they felt a huge pain due to lack of anaesthesia.

During the dentist operation, the TDMS continues sending its pre-calculated signals to the tooth. When the anaesthesia’s effectively starts to decline, the patients will perceive the signals and would inform the dentist about their perception. The dentist has to decide whether he/she wants to continue its operation or has to inject anaesthesia. During the operation TDMS has to be able to provide constant and accurate signals to the tooth. Any errors may result in misinforming the patients and dentists and end up in a huge pain for patients.

Retrieving input

data regarding

patients tooth

perception and pain

threshold

Analyzing the

input signal

Processing and

generating the

signal

Providing a unique

output signal with

specific amplitude

and frequency



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2.2 Electrical Requirement

2.2.1 The power supply shall be sufficient enough to provide the appropriate current for our device.

2.2.2 The power adaptor should be applicable with a wall supply of 110V/120V at 60 Hz AC, which is common for North American wall outlets.

2.2.3 The current source should be very stable and accurate to simultaneously provide a precise and constant current.

2.2.4 Instead of power adaptor, an appropriate portable power source may be used. The power adaptor should at least last for two weeks before requiring recharging it again.

2.2.5 The portable power supply should last for at least 4 years before requiring replacing it with a new one.

2.2.6 Key current and voltage nodes shall be easily accessible for adjusting, troubleshooting, and debugging.

2.2.7 An appropriate back up power source should be available for replacement.

2.3 Mechanical Requirements

2.3.1 The clamp should be very flexible to be easily mounted on different tooth.

2.3.2 The springs which support the electrode should be strong enough to provide a proper contact for electrodes with tooth.

2.3.3 The electrodes and springs should be operational for at least 2 years before requiring replacement.

2.3.4 The electrodes should be made from materials which are biocompatible and would not cause any health risk to patient.



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2.4 Environmental Requirements

2.4.1 The circuit box of the device needs to operate normally in typical dental office temperatures (15-30 degrees Celsius) [1].

2.4.2 The circuit box of the device must operate reliably in typical dental office humidity conditions (about 50 %) [1].

2.4.3 The clamp set-up needs to survive the corrosive environment of mouth (humidity as high as 80%) even when the device is not operating.

2.4.4 The device and clamp set-up must work reliably in mouth environmental conditions while tooth is isolated and mouth is open (Temperature: ~35 degrees Celsius, Humidity: 5%- 63%) [2]

2.4.5 The clamp set-up needs to be sterilizable to work safely as it is reused for different patients.

2.5 Physical Requirements

2.5.1 The proposed clamp should be made with the materials that are capable of being sterilized in high temperature and under sterilization chemicals.

2.5.2 Wires that connect the tooth of the patient to the TDMS should be insulated with rubber, which can also be sterilized.

2.5.3 The size of the clamp should be same as the standard clamps that are currently used in dentistry.

2.5.4 The product (TDMS) should have small physical aperture that can be easily carried, used and placed in the dental assistant’s tray.

2.6 Standards

2.6.1 The dental clamp shall conform to Medical Grade stainless steel specifications.

2.6.2 The clamp also shall meet the QSR 820 standards.

2.6.3 The device shall conform to CSA.

2.6.4 The Insulation used on the wires shall meet CSA requirements.



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2.7 Safety Requirements

2.7.1 The wires connecting the tooth to the device should be carefully insulated such that there is no danger of a short circuit in the mouth of the patient during the usage of the device.

2.7.2 The device should have safety feature to indicate any hazardous condition on the device in case of parts failure such as overload signal indicator, short circuit indicator.

2.7.3 The device shall be able to detect mechanical and electrical failure. If any error occurs TDMS shall notify the dentist that an error has occurred.

2.7.4 The clamp shall not bodily injure the gum of the patient.

2.7.5 The clamp should not be loose on the tooth and shall be in such a way that can be easily placed on the tooth without any damage to the connections and circuit structure.

2.7.6 The electronic components of the chair shall not cause interference with other parts.

2.7.7 If there is a break in the current to the tooth, the machine should shut off.

2.7.8 The device should have an emergency shut off button, Or the wire should be easily disconnected from the machine side to break the current.

2.8 Performance Requirements

2.8.1 The current generator has to have a safety precautious to limit its maximum output current.

2.8.2 The signal generator has to provide accurate signals with precise output magnitude and frequency. The difference between perception threshold and pain threshold is in µA range. Any error more than 15% would cause the signals to stimulate the pain nerves and cause a huge pain for patients.

2.8.3 The device should have a safety button which the dentist could be able to quickly shut the entire device completely in the case of an emergency.



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2.9 Reliability and Durability

2.9.1 The clamp should withstand day-to-day physical treatment.

2.9.2 The device should be serviceable by a trained professional.

2.9.3 The device should be serviced every three years to assure its precise functionality.

2.9.4 The power supply should be able to withstand the common fluctuation of the wall outlets.

2.9.5 In case of using portable power source, the batteries should provide a constant power before completely ding off.

2.9.6 The clamp and electrodes should withstand the chemical condition of patient mouth. They have to be insensitive to the reactivity of various enzyme of patient’s mouth. (They have to be biocompatible)

3 Clamp The rubber dam clamp is used to isolate a designated tooth or teeth in the mouth before certain operation. The rubber dam provides a clean and dry field of operation and improves the dentist’s view of the operating site. The numbers of holes will be punched in the rubber dam; it is stretched to fit over each designed tooth. To maintain a snug fit around the neck of the tooth a rubber dam clamp will be used. These clamps are made of spring steel in various sizes.

Figure 3-1 – Dental Clamp

A wire from TDMS will be connected to the tooth via the clamp. Because the middle of the tooth in a gingival-occlusal plane stays dry from saliva during the procedure, the connection of the TDMS to the tooth is ideal if placed in middle of the tooth. A solid cylindrical extension from the clamp would extend toward the tooth. In order to avoid current transfer to the clamp, the solid stainless cylinder will be coated with a plastic material and then a stainless spring would be extended toward the tooth from the cylinder. The stainless steel spring would function to snugly attach the TDMS wire to the tooth, as seen in Figure 3-2



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Figure 3-2 – Simple Overview of TDMS

The wire, spring, clamp unit should be inseparable for patient safety against

swallowing any piece. Rubber dam clamps have been known to be swallowed accidentally. They have also ended up in patient’s lungs and had to be removed by surgery. Currently to avoid the patient swallowing the rubber dam clamp, a piece of floss is tied to the clamp. With the TDMS machine, the wire serves this function and saves time from tying and fumbling with tying a floss.

3.1 General Requirements

3.1.1 The proposed clamp should be made with the materials that are capable of being sterilized in high temperature and under sterilization chemicals.

3.1.2 The spring should be made with stainless steel that is capable of being sterilized.

3.1.3 The rubber dam clamp should be made with spring steel in order to give the clamp flexibility in use



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3.2 Physical Requirements

3.2.1 The size of the clamp should be same as the standard clamps that are currently used in dentistry.

3.2.2 The size of the spring should be such that it allows attachment of the TDMS wire from a variety of clamps to the middle of the tooth.

3.2.3 The height of the spring for each type of clamp depends on the tooth type which it attaches to and is listed in the following table:

Type of Clamp Length of spring

12A 5-7 mm 13A 5-7 mm 2A 3 mm 212 3 mm

Table 3-1 Spring Lengths for Variuos Clamps



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4 User Interface Unit The user interface panel will contain a few buttons as inputs from the operator and a screen as the output which shall display the current that the device is operating at. In addition, small warning lights will also alarm the user about conditions such as low battery and overload. A possible User Interface Unit is shown below:

Figure 4-1 – User Interface

4.1 General Requirements:

4.1.1 There will be buttons to increase and decrease the current by the dentist and another button, set, to choose the current value shown on the display as the output; these buttons are inputs.

4.1.2 There will be a display screen that will inform the dentist of the output current; this screen is an output of the device.

4.1.3 There will be a button for turning the power of the device on and off; this is another input from the user. A small LED will light-up to indicate when the device is on; this light is an output.

4.1.4 There will be warning lights to inform the operator about low battery and overload conditions; these are outputs.

4.2 Usability and Physical Requirements

4.2.1 Dentists have enough complex devices to deal with and enough things to keep track of and therefore the user interface unit must be simple and easy to use, and designed in a way to reduce unintentional user errors.

4.2.2 A SET button is intended to be included aside form the up and down buttons so that the operator will have a chance to see the current to be outputted first on the display and then choose the appropriate output by pushing the SET button. This will reduce the chance of cranking up the current unintentionally. The decrease/increase of current in very small steps



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by the DOWN or UP buttons also contributes to this cautionary design consideration.

4.2.3 Push buttons are to be chosen over a knob for adjusting the current to prevent sudden uncontrolled changes in the output.

4.2.4 Using standard colors for LEDs (orange for warning outputs and green for the ON state of the device) shall make the communication between the device and the operator more effective.

4.2.5 Using intuitive conventions for the buttons responsible for increasing/decreasing the current (e.g. arrows pointing up and down or +/- indicating increase/decrease action) shall reduce errors by the users.

4.2.6 Appropriate spacing between input buttons and their location on the user interface panel shall reduce the chance of unintentionally pressing the wrong button by the operator. In addition, placing the output indicators appropriately on the panel will increase the chances of them being noticed by the user.

4.2.7 A digital display will be preferred over other kinds to eliminate uncertainties in reading the output current by the operator.

4.2.8 The material on the panel shall be chosen so that they can withstand the possibly wet hands of the dentist and also be easy to clean.

5 System Test Plan Various parts of our system will first be tested separately to ensure proper functioning in the component level. For instance, the constant current generator will be tested with a circuit that can provide a range of impedance values simulating those of a tooth and surrounding tissues. This will ensure constant current generation in the presence of various load values. The physical design and requirements of the clamp set-up will be tested on tooth models in addition to actual human teeth. These tests will assist us to ensure that the clamp and the electrodes will fit properly on the various teeth shapes and that they make the proper and reliable contact with the right part the tooth. The user interface unit and its characteristics such as being user friendly and easy to use and communicate with will be assessed by presenting it to a number of dentists and asking for their feedback on its usability properties. All of this said, the main method of testing our device will be human object, primarily the members of our group and later on, upon making a reliable version, volunteer patients at dentists offices. We have the assistance of dentists, especially Dr. Kevin Aminzadeh who has



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been a great help and has offered further assistance throughout the project development, available to us which will make it possible to more readily test the functionality of our device; we will have anesthetised teeth available to us which will give us the opportunity to test TDMS at various points of its development in a realistic setting and get direct feedback from the person who is under the test.

6 User Documentation

6.1.1 User documentation will be conducted via a website. We will include an online manual, and constantly update the site with various other user feedback.

6.1.2 The language of the user manual will be very simple. We aim to have a product that is easy to use, and requires minimal reading of the user manual.

6.1.3 The user manual will be written in many languages, including, but not limited to: English, French, Spanish, Mandarin, Japanese.

7 Conclusion This Functional Specification document outlines the requirements to be considered when designing and building our device. Meeting these requirements will help ensure that TDMS will function as expected, reliably and safely in typical work environments. In addition, providing a user friendly interface will make the device easy to operate and will reduce the chances of user errors. Even though slight deviations from this document may occur, it will be used as a guideline that will consolidate and coordinate the design and production processes and as a result guide us in the road to the ultimate goal of this project.



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8 References

1. Canadian Centre for Occupational Health and Safety, “What is meant by thermal comfort?”, OSH Answers: Thermal Comfort for Office Work, August 23, 2005. [Online]. Available at: http://www.ccohs.ca/oshanswers/phys_agents/thermal_comfort.html. [Accessed: October 11, 2007].

2. Martins De Araujo MT, Vieira SB, Vasquez EC, Fleury B. Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy. Chest 2000;117(1):142-147. [Online]. Available at: http://www.talkaboutsleep.com/sleep-disorders/archives/Snoring_apnea_abstract79.htm [Accessed: October 11, 2007]

3. Virtanen A. Electrical Stimulation of Pulp Nerves-Comparison of Monopolar and

Bipolar Electrode Coupling. 1985. Elsevier.

4. Dr.Kevin Aminzadeh, Dentist

5. Pepper M and Smith D. An electric tooth pulp vitality tester. 1981. Medical & Biological Engineering & Computing

6. http://www.shopbot.ca/c-111-0-0-1.html

7. <http://www.directpage.com/?OVRAW=beeper&OVKEY=beeper&OVMTC=sta

ndard&OVADID=910468022&OVKWID=4437118022>

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