Tooth Guard for the Laryngoscope

1
Tooth Guard for the Laryngoscope
University of Pittsburgh Senior Design BioE
1160/1161
Nate Angeloff Mike Matthews Virginia Penascino
Sean Ritchie April 18, 2006 Mentors Jim
Menegazzi, PhD Manuel Vallejo, DMD, MD
2
Overview

• A Laryngoscope is an instrument used to examine
  the interior of the larynx during intubation.
  The traditional laryngoscope can be difficult to
  use. It can cause oral cavity and soft tissue
  damage
• Oral cavity damage can include tooth fracturing
• We designed a tooth guard that would slide over
  the Miller blade to provide a cushion against the
  forces applied to the upper and lower teeth
• This product is used in pre-hospital emergency
  care and in the hospital setting

3
Background

• Dental injury is the most common medical legal
  complaint against anesthesia providers (33-38)
• Average cost 1,672 2,378 (0 8,038)
• 62 of teeth damaged by the laryngoscope have
  been previously restored or are associated with
  periodontal disease
• Incidence of dental injury
• 0.02 - 0.7 (retrospective)
• 12.1 (prospective)
• UPMC paid for 25,000 worth of dental repair from
  October to June 2000

4
Teeth Most at Risk

• Upper maxillary central incisors are most at risk
• Single tooth usually involved - only 13 gt 1
  tooth
• Upper left maxillary central incisor is most at
  risk (51)

5 8 16 51 19 0
5
Facts

• Damage is 5x more likely with a pre-existing
  dental condition
• Most injuries Þ crown fractures partial
  dislocations
• Non restored teeth Þ incisal chipping
• Isolated teeth Þ dislodgement
• Orthodontic treatment Þ tooth mobility and root
  resorption

6
Problem Statement

• Current Solutions
• Gauze roll
• Oropharyngeal Airway
• Bite Block
• Bitegard
• Endoscopic
• Not for emergency situations
• Wont work during a difficult intubation

7
Features Benefits

• The laryngoscope is not being redesigned.
  Instead we are manufacturing a sheath to cover
  the points on the blade that apply pressure to
  the teeth
• The sheath will be made out of a soft, elastic
  material to provide ample cushioning for the
  patients teeth
• The guard was manufactured and fitted to the
  blade so that visibility and lighting are
  minimally affected

8
Design Requirements

• The guard must fit in the oral cavity
• It needs to cover the area of the blade that
  contacts the upper maxillary incisors
• The width of the guard must be larger than the
  blade so that it contacts more teeth
• Using a soft material will cut down on incidental
  impact damages
• The least amount of material should be used to
  ensure greatest amount of visibility. This also
  minimizes cost

9
Proposed Solution

• The insertion site is machined to the exact
  specification of the Miller blade
• This could easily be made universal for other
  sizes and different manufactured blades
• The increased width and flattened sides of the
  guard helps distribute the force over more than
  one tooth

10
Prototype Fabrication

• SolidWorks model was sent to quickparts.com
• The prototype was fabricated using PolyJet Tango
  Elastomer in stereolithography

11
Materials

• New PolyJet Tango material that simulates the
  feel of flexible materials such as rubber or
  silicone
• Tango Black is the softest material they provide
  with a SHORE A hardness of 61 durometers
• Shore (Durometer) test measures the resistance of
  plastics toward indentation and provides an
  empirical hardness value
• Silicone rubber tubing ranges from 40 to more
  than 65

12
Set Up

• Two models of the upper jaw were obtained from
  the Wiser center
• The teeth in the model were all joined
• The sides of the upper maxillary incisors were
  shaved down using a razor blade
• Each jaw model was super glued and screwed to a
  piece of wood
• The wood was on a hinge which allowed the model
  jaw to pivot while the force transducer was
  placed directly underneath
• Using a prying motion with the laryngoscope, the
  teeth were broken

13
Testing

• First we broke model teeth with the guard and
  without the guard
• After the model teeth were broken, we inserted
  human teeth into the jaw mold
• The teeth were supplied by Dr. Vallejo and
  drilled at the dental school
• We were hoping for a larger force on the jaw when
  the guard was used
• Indicating the force was being dispersed over
  more teeth, preventing any of them from breaking

14
Results

• First the teeth were broken without the guard,
  the average force required for fracture was 203.6
  N
• These forces are for the model teeth, not real
  human teeth

15
Results (cont)

• This is us breaking a tooth without the guard on
  the laryngoscope

16
Results (cont)

• Next we attempted to break the teeth with the
  guard but were unsuccessful
• The guard spread the force out so much that none
  of the teeth broke, even when using as much force
  as possible

17
Results (cont)

• This is us attempting to break a tooth with the
  guard on the laryngoscope

18
Results (cont)
  Force Required to Fracture Without Guard (N) Force Required to Fracture With Guard (N)
Trial 1 221 No Fracture
Trial 2 211.5 No Fracture
Trial 3 188.2 No Fracture
Trial 4 193.8 No Fracture
Average 203.625 No Fracture
19
Results (cont)

• Once the model teeth had been broken we drilled a
  hole in the model and inserted the human teeth
• We were unable to obtain data from the human
  teeth because the models broke before the teeth
  fractured

20
Jaw model after failure
21
Competitive Analysis

• Disposable and/or Sterilizable Cushioning Device
  for the Laryngoscope

• Teeth Protector for Laryngoscope Blade

• Laryngoscope Blade with Protective Insert

Free Patents Online freepatentsonline.com
22
Competitive Analysis

• Current Solutions
• (on the market)
• Gauze roll
• 10/box 10 boxes for 7.38
• Oropharyngeal Airway
• (0.70 each in bulk 0.50 each)
• Bite Block
• BiteGard (50/box) (65)
• Endoscopic (4.90 each)
• Used in approximately 2 of cases
• Our price - 1.20 per guard

BiteGard
23
Competitive Analysis

• Strengths
• Distributes load over more teeth to decrease
  force on primary tooth
• Disposable
• Can be universal Mac and Miller
• For emergency use
• Weaknesses
• Bulky
• Slipping from desired location

24
Quality System Considerations

• Manufacturability
• Simple Design
• Made out of PolyJet Tango Elastomer
• Stereo lithography to simulate rubber
• Proposed Siloxane manufacturing
• Human Factors
• Decrease the damage to the oral cavity caused by
  intubation
• Universal - Slides over Miller Blade but can be
  made to slide over Mac Blade also
• Easy to use
• Disposable

25
FDA Regulation

• TITLE 21--FOOD AND DRUGS
• CHAPTER IFOOD AND DRUG ADMINISTRATION DEPARTMENT
  OF HEALTH AND HUMAN SERVICES
• SUBCHAPTER H--MEDICAL DEVICES  
• PART 868 ANESTHESIOLOGY DEVICES
• Subpart F Therapeutic Devices
• Sec 868.5820 Dental protector
• Identification A dental protector is a device
  intended to protect a patient's teeth during
  manipulative procedures within a patient's oral
  cavity
• Classification Class 1
• Class I (general controls) The device is exempt
  from the pre-market notification procedures in
  subpart E of part 807 of this chapter subject to
  the limitations in 868.9
• US Food and Drug Administration
  http//www.accessdata.fda.gov/scripts/cdrh/cfdocs/
  cfCFR/CFRSearch.cfm?FR868.5820

26
Economic Considerations

• Market size
• One study indicates 500,000 intubations are
  performed worldwide per day
• http//web.mit.edu/cortiz/www/KristinThesis.PDF
• A second study stated that 12,000 intubations
  were performed by paramedics per year in
  Pennsylvania
• This number does not include in-hospital
  intubations
• http//www.medicalnewstoday.com/medicalnews.php?ne
  wsid27634

27
Economic Considerations

• Siloxane with a shore hardness of 60 A will be
  manufactured by Instrumentation Industries or
  Injection-moldings.com
• Cost 15,000 0.20per
• Selling price 1.20 per guard
• Potential market size
• Earning potential

28
Design Alternatives

• The width is the most important component in the
  design
• The height was decreased to remove unnecessary
  material

29
Work Breakdown
Nate Angeloff Mike Matthews Virginia Penascino Sean Ritchie
Design X X    
Clinical Interviews X   X  X
Material Research X X    
Stress Analysis   X  X
Prototype X X    
Testing X X  X X
DHF X X X X
30
Acknowledgements

• Manuel Vallejo, DMD, MD
• John ODonnell, CRNA, MSN
• Jim Menegazzi, PhD
• Mark Gartner
• Generous gift from Dr. LindaBaker and Dr. Hal
  Wrigley