CHAPTER 2 SNORING AND OBSTRUCTIVE SLEEP APNEA
2.3 Treatments
2.3.2 Non-surgical Treatments
2.3.2.3 Oral Appliance
Mask problems
Poor fit, discomfort, claustrophobia Air leakage, dry eyes, conjunctivitis Skin rashes/abrasions 4 Failure to gain sufficient recognizable benefit 5 Failure to understand medical necessity
6 Failure to receive educational, instructional, and motivational counseling at onset 7 Cost, insurance noncoverage
2.3.2.3 Oral Appliance
The application of the oral appliance for the treatment of obstructive sleep apnea was first introduced in 1984 [25]. Various oral appliances have been developed for the treatment of snoring or OSA. With different designs, they can be classified into three basic categories as follows:
z Mandibular advancement devices (MADs): it also termed as the Mandibular reposition devices (MRDs). These are removable devices which are worn at night during sleep. Most devices require dental impression, bite registration, and fabrication by a dental laboratory. Those devices are fixed to upper and lower teeth and are adjusted to advance the mandible. The amount of protrusion is adjusted to meet the therapeutic requirements, comfort, and tolerance. Many devices have a fixed degree of advancement. Some are adjustable in a limited degree.
z Tongue-retaining device (TRD): it is designed to keep the tongue in an anterior position during sleep. The tongue is held in place by a negative pressure in a soft plastic bulb, which protrudes out of the mouth. The lips are closed over a flange which fits between the lips and teeth to hold the device.
z Soft palate lift (SPL): these removable devices are also for nighttime use during sleep. A posterior extension is fitted up upper teeth to lift the soft palate and uvula out of the pharyngeal airway. These devices have not demonstrated efficacy in reducing either snoring or OSA.
All oral appliances produce downward rotation of the mandible, many of them also move forward the mandible by design. In a comparative study, a strong patient preferences appeared for the MAD. The MAD was an effective treatment and the TRD and SPL were less tolerable and significant improvements [26].
Oral appliances may improve upper airway patency during sleep by enlarging the upper airway or by decreasing upper airway collapsibility. The mechanism action of oral appliances is at least three ways. First, they bring the mandible and base of tongue forward. Second, they stabilize the mandible to prevent it from falling open during sleep. And third, they alter the mandibular position through downward rotation, thereby causing an increase in cross
sectional airway size and muscle tone. After the oral appliance therapy, snoring is improved in 73% to 100% of patients [27]. Those patients with mild to severe OSA have a 52% chance of being able to control their sleep apnea to reach a level of AHI less than 10 by using oral appliances [28]. Whole OAs are less effective than CPAP but may be better accepted by patients than CPAP in whom used both treatments. The common side effects of oral appliance, such as excessive salivation, dryness of the mouth, or transient discomfort, may prevent early acceptance. The major long-term problems are temporomandibular joint (TMJ), or jaw discomfort and limited movement of the teeth. Those effects can be minimized if the appliance is adjusted to so as to avoid excessive advancement of the mandible.
The standard treatments of snoring and OSA promoted by AASM include surgery, CPAP, and oral appliance. Among all of three, CPAP and oral appliance are noninvasive treatments.
The CPAP is more effective than oral appliance, but the compliance of oral appliance is better than CPAP. Further, some drawbacks of CPAP in the equipment, interface, or appearance will lead to intolerable to use or inconvenience of usage in some occasions. Therefore, this study will focus on the oral appliance, even the mandibular advancement device, to innovate.
CHAPTER 3
MANDIBULAR ADVANCEMENT DEVICE
3.1 Patents
The patent review of this study is based on the patents published in the United States since 1976. They can be searched from the patent full-text and full-page image databases in the United States Patent and Trademark Office (USPTO) [29]. According to the patents, the development and trend in specific techniques can be realized. In this study, the aim of patent search focuses on the mechanisms of anti-snoring devices especially the mandibular advancement devices. Referring to the patent review, the analysis results can be classified into several categories by functions which will be discussed in following subsections. In general, patents are invented to improve the disadvantages existed in prior arts. The disadvantages refer to the analysis including uncomfortable to use, low compliance, high cost, can not or complex to adjust, bulky volume, lack of customizability, and etc.
3.1.1 Fixer
The function of the fixer is used to install the mandibular advancement device in the oral cavity by fixing on the teeth. The usage of most MADs is inserting into the mouth during sleep and removing after getting up. Because of the requirement of removability, the fixer is usually designed just to fit but not mount on the teeth. Thermoplastic materials are usually used to form the fixer like a mouthpiece. Some appliances add clasps on to make MAD more stable during wearing time. Finally, a little parts of MADs are directly fixed on the teeth by mounting. Those devices are usually used to treat the malocclusion, but the advancement of the mandible also can eliminate snoring (Table 3.1-1).
Table 3.1-1 The fixers of mandibular advancement device
Thermoplastic material
Thermoplastic material and Clasp
Mount directly
U.S. Patent No. 5365945 [30] U.S. Patent No. 5427117 [31] U.S. Patent No. 5645423 [32]
3.1.2 Connector
In the two-pieces MAD, the connector connects the upper and lower mouthpiece adjustably. Different from the two-pieces MAD, the one-piece MAD which is entirety made by one material does not need the connector and cannot be adjusted. Therefore, all the MADs discussed here are the two-piece MAD which various connectors are used (Table 3.1-2).
z Button
An elastic button-like connector couples with a aperture to interconnect upper and lower mouthpiece. This kind of connector connects two mouthpieces in a fix degree of advancement without the function of adjustment during using. The decision of degree of advancement is applied during the impression process by the therapist.
z Screw
The screw connector means either the traditional screw or the dual-thread screw.
Using screws as the connector to connect the upper and lower mouthpiece can be very tight and high strength. However, it is usually not convenient to use because it
needs be wrenched by a screw driver.
z Wire
Wire connector can be shaped to the oral cavity to prevent the movement space of tongue from being occupied by connected and adjusted mechanism. The strength of the wire may be concerned according to its failure.
z Surface contact
An object is fixed to one mouthpiece and contacts with another one. This condition can be considered as that upper and lower mouthpieces are connected by contacting.
Therefore, contacting is the connector in this kind of appliance.
z Post
The post is coupled with the aperture restrainedly or freely depended on the shape of the post. It may be single or numerous locating in the anterior or posterior portion or both on the mouthpiece.
z Interlocking member
Interlocking member, for example the Velcro, is a connector with two phases that are engaged by contacting and are disengaged by tearing. It can be connected in any position that is convenient to use and adjust. But it is also easy to be separated which leads to the poor strength.
z Elastic band
Elastic band is a flexible material used to pull the mandible advancement. Because of the flexibility, the movement of the mandible still keeps large degrees of freedom after advanced. It means it is unstable.
z Linkage
upper and lower mouthpieces to drive the mandible advancement. The link may be a scope-like structure that is variational in length.
Table 3.1-2 The connectors of MAD
Button Wire Surface contact
U.S. Patent No. 5313960 [33] U.S. Patent No. 5409017 [34] U.S. Patent No. 5566683 [35]
Post Interlocking member Screw
U.S. Patent No. 5499633 [36] U.S. Patent No. 5642737 [37]
Elastic band Linkage
U.S. Patent No. 5755219 [38] U.S. Patent No. 6418933 [39] U.S. Patent No. 5365945 [30]
3.1.3 Adjustor
In aforementioned descriptions, connectors are used to connect the upper mouth piece and lower mouthpiece to form the MAD. The adjustor is either as a part of the connector or as an individual component to perform the function of adjustment. The way of adjustment can be divided into two types: continuous adjustment and position-fixed adjustment. The direction of adjustment makes the mandible not only protraction and retraction but also elevation and depression (Table 3.1-3).
3.1.3.1 Protraction and Retraction z Series of aperture
This is one of position-fixed adjustments. The series of apertures are usually coupled with the screw or the post, and they are equal in interval. Choose one of those apertures as the preferred position to connect.
z Screw
The screw works as a continuous adjustor with high precision. It can satisfy the requirement of adjustment in a small amount. The screw usually works as a component of the connector to adjust its position.
z Dual-thread screw
The dual-thread screw is a combination of two screws in the opposite threaded direction. The performance of the dual-thread screw is double to the traditional screw.
z Conjugate shape
Identical shape arranges in series to connect with its conjugate shape face-to-face worked as a position-fixed adjustor. The commonly used shape is the saw-shaped
surfaces together.
z Interlocking member
This kind of adjustor may be considered as a continuous adjustor or a position-fixed adjustor with tiny interval between one and one interlocking members. It is easy to operate by touching the interlocking member together anywhere you preferred.
z Elastic band
The degree of advancement depends on the length of the elastic band. Some additional components are used to adjust the length. The force applied on the mandible may be changed by replacing the elastic band in different stiffness.
z Slot
The connector slides in the slot to adjust the position of the mandible continuously.
A fastener is usually used to fasten the connector on the slot in a preferred position.
z Replace component
Various components are applied for replacing to change the position of the mandible.
This kind of adjustment is position-fixed and may be inconvenient to use because of lots substitute components should be prepared.
Table 3.1-3 The adjustors of MAD (Protraction and retraction)
Series of aperture Elastic band Dual-thread screw
U.S. Patent No. 5365945 [30] U.S. Patent No. 5755219 [38] U.S. Patent No. 5409017 [34]
Conjugate shape Interlocking member Screw
U.S. Patent No. 5570704 [41] U.S. Patent No. 5642737 [32]
Slot Replace component
U.S. Patent No. 6769910 [42] U.S. Patent No. 5427117 [31] U.S. Patent No. 6845774 [40]
3.1.3.2 Elevation and Depression
The adjustment of elevation and depression of the mandible is not usually designed as a function of the MAD. The purpose of this function is to make the product suitable for most people. The methods which used to adjust the elevation and depression of mandible include replacing component, screw, slot, and surface contact (Table 3.1-4).
Table 3.1-4 The adjustors of MAD (Elevation and depression)
Replace component Screw
U.S. Patent No. 5947724 [43] U.S. Patent No. 6055986 [44]
Slot Surface contact
U.S. Patent No. 6305376 [45] U.S. Patent No. 6983752 [46]
3.1.4 Acting Force
The force acting on mandible to advance it can be divided into the pulling force and the pushing force. The pulling force usually acts from the anterior portion of upper mouthpiece to the posterior portion of the lower mouth piece, the pushing force acts oppositely. However, most connectors are connected between the same portion of upper and lower mouthpiece. The force acts as a perpendicular force on the connector, and it is used to prevent the mandible backward which is similar to the pushing force. Therefore, the acting force includes the perpendicular force, pushing force, and pulling force. In the mechanical terminology, they are shear force, compression force, and tensile force acting on the connector respectively (Table 3.1-5).
Table 3.1-5 Types of acting force of MAD
Perpendicular force Pushing force Pulling force
U.S. Patent No. 5365945 [30] U.S. Patent No. 6418933 [39] U.S. Patent No. 5755219 [38]
3.1.5 Lateral Movement
A function of allowing limited lateral movement during using the MAD is required. The lateral movement can prevent facial muscles from stiff and avoid the TMJ dysfunction. That will make the patients feel more comfortable and tolerated in using the MAD. The methods which have promoted to patents include using slots, linkages, surface contact, and elastic bands. Using the slot and the linkage to perform this function are better than the surface
ensure the therapeutic effect will not be affected by non-limited motion (Table 3.1-6).
Table 3.1-6 Types of lateral movement of MAD
Slot Surface contact
U.S. Patent No. 5868138 [47] U.S. Patent No. 5427117 [31]
Linkage Elastic band
U.S. Patent No. 6012920 [48] U.S. Patent No. 5755219 [38]
According to the patent reviews, more systematic results of analysis are presented. Those results can help to realize the disadvantages in prior products and find out the requirements.
Further, those will be very useful for patent around that will prevent the new design from infringing other intelligence properties.
3.2 Products
The U.S. Food and Drug Administration (FDA) is responsible for protecting the public health by assuring the safety, efficacy, and security of human and veterinary drugs, biological products, medical devices, food supply, cosmetics, and products that emit radiation in the United States [49]. The mission of Center for Devices and Radiological Health (CDRH), one department of FDA, is to assure that new medical devices are safe and effective before they are on market. The FDA has classified all the medical devices into three classes. Each of those devices is assigned to one of three classes based on the level of control necessary to assure safety and effectiveness of the device. Everyone who wants to market Class I, II, and some III devices intended for human use in the U.S. must submit a premarket notification, 510(k), to FDA at least 90 days before marketing unless the device is exempt from 510(k) requirements.
The oral appliances are assigned to the Class II devices [50] that must receive a 510(k) from FDA for the treatment of snoring or OSA. Therefore, all the OAs for snoring and/or OSA can be searched within which devices have received the 510(k) clearance and are available in the CDRH 510(k) database.
For the purpose of searching for all related products of the snoring or OSA treatment, the more effective method is to search by category rather than by other terms. Each category is referring to an individual product code. The intraoral devices for snoring and/or OSA are referring to the following product codes: “LRK”, Anti-Snoring Device; “LQZ”, Jaw Repositioning Device. There are totally 72 products in these two categories including all kinds of oral appliances. Depending on sifting all the products carefully, there are at least 16 products which are the adjustable two-pieces mandibular advancement devices. These devices with their specification are collected and listed in Table 3.2-1 and Table 3.2-2.
Table 3.2-1 List of adjustable MAD products
Model Applicant Approval Date
Klearway® Dr. Alan A. Lowe, Inc. 05/25/1995 Silencer® Silent Knights Ventures, Inc. 10/30/1995 Adjustable PM Positioner® Jonathan A. Parker, D.D.S. 02/08/1996
Herbst Appliance® Univ. Dental Assoc. Dept. of
Orthodontics 03/20/1996
TAP® Airway Management Inc. 01/24/1997
Silent Nite® Glidewell Laboratories 09/18/1997
EMA® Frantz Design, Inc. 09/29/1997
Adjustable TheraSnore® DISTAR, Inc. 11/12/1997
Snoring Control Device® Kenneth Hilsen 01/09/1998
Snore-Aid plus® Dental Imagineers, LLC 07/22/1999
NORAD® Dennis R. Bailey, DDS 05/28/2002
SUAD® Strong Dental Inc. 07/08/2003
OASYS Oral/Nasal Airway System® Mark Abramson, D.D.S., Inc. 08/26/2003 MDSA TM RJ & VK Bird Pty Ltd. 10/27/2004
SomnoMed MAS ® Somnomed Ltd 07/12/2005
TAP-T® Airway Management Inc. 07/12/2006
SomnoGuard AP/AP Pro® Tomed Dr. Toussaint GmbH 09/08/2006
Table 3.2-2 Comparison of adjustable MAD products
Model
Klearway® Silencer®
Photo
Company Dr. Alan A. Lowe, Inc. Silent Knights Ventures, Inc.
Inventor Alan A. Lowe (Canada) Leonard W. Halstrom (Canada)
Approval Date 05/25/1995 10/30/1995
FDA
510(k) Reg. No. K950763 K954530
Treat Snoring Yes Yes
Treat OSA Yes Yes
Connector Wire Screw/Post
Adjustor (P-R) Dual-thread screw Series of aperture
Adjustor (E-D) N/A N/A
Lateral movement Slot Slot
Patents US 5409017 US 5365945, US 5868138
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model
Adjustable PM Positioner® Herbst Appliance®
Photo
Company Jonathan A. Parker, D.D.S. Univ. Dental Assoc. Dept. of Orthodontics
Inventor Jonathan A. Parker (U.S.) (No data)
Approval Date 02/08/1996 03/20/1996
FDA
510(k) Reg. No. K955503 K955822
Treat Snoring Yes Yes
Treat OSA Yes Yes
Connector Wire Linkage
Adjustor (P-R) Dual-thread screw Screw
Adjustor (E-D) N/A Elastic band
Lateral movement Linkage Linkage
Patents US 5816799 (No data)
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model
TAP® Silent Nite®
Photo
Company SCHEU-DENTAL GmbH Glidewell Laboratories
Inventor W. Keith Thornton (U.S.) (No data)
Approval Date 01/24/1997 09/18/1997
FDA
510(k) Reg. No. K964516 K972424
Treat Snoring Yes Post (Hook)
Treat OSA Yes Screw
Connector Post (Hook) Slot
Adjustor (P-R) Screw N/A
Adjustor (E-D) Slot US 6305376
Lateral movement Surface contact Elastic band
Patents US 6305376 (No data)
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model
EMA® Adjustable TheraSnore®
Photo
Company Frantz Design, Inc. DISTAR, Inc.
Inventor Don E. Frantz (U.S.) Thomas E. Meade (U.S.)
Approval Date 09/29/1997 11/12/1997
FDA
510(k) Reg. No. K971794 K973038
Treat Snoring Yes Yes
Treat OSA Yes Yes
Connector Elastic band Elastic band
Adjustor (P-R) Replace component Replace component
Adjustor (E-D) Replace component Replace component
Lateral movement Elastic band Elastic band
Patents US 5947724, US 6109265 US 5947724, US 6109265 (All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model
Snoring Control Device® Snore-Aid plus®
Photo
Company Ridgewood Dental Associates Dental Imagineers, LLC Inventor Kenneth L. Hilsen (U.S.) William A. Belfer (U.S.)
Approval Date 01/09/1998 07/22/1999
FDA
510(k) Reg. No. K963591 K991449
Treat Snoring Yes Yes
Treat OSA No Yes
Connector Interlocking member Post +Surface contact
Adjustor (P-R) Interlocking member Elastic band (Bind posts)
Adjustor (E-D) N/A Surface contact
Lateral movement Surface contact Surface contact
Patents US 5611355 US 20030234022
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Inc. Strong Dental Inc.
Inventor Charles D. Kownacki (U.S.) Patrick J. Strong (Canada)
Approval Date 05/28/2002 07/08/2003
FDA
510(k) Reg. No. K020893 K023836
Treat Snoring Yes Yes
Treat OSA Yes Yes
Connector Elastic band Linkage
Adjustor (P-R) Series of aperture Elastic band
Adjustor (E-D) N/A Elastic band
Lateral movement Surface contact Elastic band/Linkage
Patents US 20040177853 US 6418933, US 6526982
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model
OASYS® MDSA®
Photo
Company Mark Abramson, D.D.S., Inc. RJ & VK Bird Pty Ltd.
Inventor (No data) John Gaskell (Australia)
Approval Date 08/26/2003 10/27/2004
FDA
510(k) Reg. No. K030440 K042161
Treat Snoring Yes Yes
Treat OSA Yes Yes
Connector Wire Post (Hook)
Adjustor (P-R) Screw/Slot (Telescope) Screw
Adjustor (E-D) Surface contact N/A
Lateral movement Surface contact Surface contact
Patents (No data) US 6845774
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model
SomnoMed MAS® TAP-T®
Photo
Company Somnomed Ltd SCHEU-DENTAL GmbH
Inventor
Richard George Palmisano
(Australia) W. Keith Thornton (U.S.)
Approval Date 07/12/2005 07/12/2006
FDA
510(k) Reg. No. K050592 K061732
Treat Snoring Yes Yes
Treat OSA Yes Yes
Connector Surface contact Post (Hook)
Adjustor (P-R) Dual-thread screw Screw
Adjustor (E-D) Replace component N/A
Lateral movement N/A Slot
Patents US 6604527 US 7174895
(All rights of the pictures belong to individual incorporation respectively)
Table 3.2-2 Comparison of adjustable MAD products (cond.)
Model SomnoGuard AP/AP Pro®
Photo
Company Tomed Dr. Toussaint GmbH
Inventor
Toussaint Winfried Dr (Germany)
Approval Date 09/08/2006
FDA
Lateral movement Surface contact
Patents DE 20018772, EP 1203570
(All rights of the pictures belong to individual incorporation respectively)
CHAPTER 4
QFD AND REQUIREMENTS
4.1 Introduction
The quality function deployment (QFD) method was developed in Japan in the 1970s and introduced to the United States in the 1980s. It is one of the best and currently the most popular technique used to generate engineering specifications from customers’ requirements [51]. The advantage of the QFD method is that it develops the required information systematically for understanding the problem during product development. Some objectives which can be achieved by using the QFD method are showing as follows:
z To understand specifications or goals for the product.
z To understand how the competition meets the goal.
z To understand what is important from the customers’ viewpoints.
z To set the numerical targets to work toward.
Furthermore, QFD is a quality control method. It supplies a process for product design to ensure the result will meet the customers’ requirements. The process can be divided into four stages [52] as follows:
z Product Planning Stage (Customers’ Requirements Æ Engineering Specifications) z Product Deployment Stage (Engineering Specifications Æ Product Specifications) z Process Planning Stage (Product Specifications Æ Manufacturing Requirements) z Production Planning Stage (Manufacturing Requirements Æ Operating Instructions) Among the four stages, the first stage is the most important one because its outcome will be
the input information of next stage. Besides, the engineering specifications are generated to be
the input information of next stage. Besides, the engineering specifications are generated to be