Auto Dispensing Prophy Angle
Ari Katz
Brendan LaBrecque
Stefan Mag
Matt Rao
Nick Starno
Capstone Design
12.04.07
The Cleaning Process
Doriot
Handpiece
Disposable
Prophy Angle
Dentifrice
(“Prophy Paste”)
• The duration of the average cleaning is approximately 5 - 10 minutes
• Dentifrice is reloaded up to one time per tooth (32 times) during cleaning
• Between 50-100% of a container of dentifrice is used per patient
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Purpose
Problem Statement:
The amount of time a hygienist spends in an awkward position can be reduced
and the dental cleaning procedure can be made more efficient.
Objective:
Integrate a dentifrice dispensation system into a disposable prophy angle to
simplify the process and reduce the overall time of the procedure.
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Benefits
Allows cleaning to become one continuous process
Reduces the duration of the cleaning
Increases cleaning efficiency in hard to reach areas
Reduces materials and sterilization processes
required for packaging
• Improved ergonomics
•
•
•
•
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Dentifrice Characteristics
• A two-phase visco-elastic material comprised of
abrasives, binders, humectants, and other agents
– Viscosity: >300 Pa*s; Re<1
– Does not behave as a fluid
– Composed of solid particles
– Abrasive
– Solid particles break down
Before Use
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After 15 Seconds
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Existing Patents
1
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Design Requirements
Required Systems
– Dispensation Mechanism
– Drive Mechanism
– Dentifrice Storage
• Size – must interface with standard handpiece, fit in any patient’s mouth,
and maintain ergonomics.
• Reliability & Ease of Use – must continuously dispense dentifrice at an
acceptable rate or allow user control.
• Safe and Sterile – must use biocompatible materials, can’t generate
excessive heat, and must be manufactured to allow for sterilization
processes.
• Low Cost – currently the cost of a container of dentifrice and a disposable
prophy angle is around 40 cents.
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Initial Designs
• Simple Design
• Rifled Tube Integrates all Required Systems
• Orifice Restricts Flow Rate
• Spring Auger Drive Mechanism
• Clutch Enabled User Control of Dispensation
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Test 1 – Auger Dispensation
Objectives:
– Investigate the feasibility of using an auger as a dispensation
mechanism
– Establish a correlation between pitch and volumetric flow rate
Test
Fixture
Medium
Grit
Dentifrice
Dremel
Tool
Scale
Q
dV ASlugdx

dt
dt
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Test 2 – Plunger Dispensation
Objectives:
– Investigate the feasibility of using a
plunger as a dispensation mechanism
Weight
Plunger
Re 
64
f 
Re
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vD

l v2
hLmajor  f
D 2g
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Test 3 – Orifice Constriction
Objective:
– Determine how much a
reduction in orifice size restricts
the flow of dentifrice
Weight
Scale
Dremel
Tool
Test
Configuration
with Taper
AY
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AX
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Test 4 – Bend Radius
Objectives:
– Determine the feasibility of transporting dentifrice around a 90º
bent flow path.
Bent Tube
Fixture
Dremel
Tool
Capstone Design
Scale
Dentifrice
Displacement
12
Test Conclusions
•
•
No constrictions
Effect of bend in flow
path is minimal
•
Auger or reservoir
must be rotating
relative to the other
No plunger
mechanism
Higher pitch yields
higher velocity and
force
•
•
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Revised Designs
• Auger dispensation
• Enables user control
• Eliminates:
– Orifice constrictions
– Bent Spring
– Excess friction and heat
generation
Design 1
Design 2
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Design 1
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Spring Auger
Bent Flow Path
Clutch System
User Control
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Design 1 Prototype Testing
Pre-Test
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Post-Test
16
Design 2
•
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Straight Flow Path
Spring Auger
Brake System
User Control
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Design 2 Prototype Testing
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Final Design
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Questions
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