RDH CE Evening Express
November 2015
The Rockwell Scale:
The Key to Evidence-Based Instrument
Selection for Dental Implant Maintenance
This presentation is supported by American Eagle Instruments Inc.
Presented by:
Angela M. Fuller, RDH, BA
Recognition and Credits
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PennWell designates this activity for 1 Continuing Education Credit.
Dental Board of California: Provider 4527, course registration number 01-4527-15026.
“This course meets the Dental Board of California’s requirements for 1 unit of continuing education.”
The PennWell Corporation is designated as an Approved PACE Program Provider by the
Academy of General Dentistry. The formal continuing dental education programs of this
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maintenance credit. Approval does not imply acceptance by a state or provincial board of
dentistry or AGD endorsement. The current term of approval extends from (11/1/2015) to
(12/31/2019) Provider ID# 320452.
Disclosure Declarations
Presenter Disclosure: Angela Fuller, RDH, BA has nothing to disclose relevant
to this program.
Commercial Support: This course was developed with commercial support by American
Eagle Instruments, Inc.
Provider Disclosure: PennWell does not have a leadership position or a commercial interest
in any products or services discussed or shared in this educational activity, No manufacturer
or third party has had any input into the development of course content.
CE Planner Disclosure: Heather Hodges, CE Coordinator does not have a leadership or
commercial interest with any commercial supporter, or with products or services discussed in
this educational activity. Heather can be reached at [email protected].
Image Authenticity: No images in this educational activity have been modified or altered.
Scientific Basis: All content has been derived from references listed and the author’s clinical
experience. Research references are provided in the bibliography and/or supplemental
materials.
Educational Disclaimer: Completing a single continuing education course does not provide
enough information to result in the participant being an expert in the field related to the course
topic. It is a combination of many educational courses and clinical experience that allows the
participant to develop skills and expertise.
Angella M. Fuller, RDH, BA
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RDH CE Evening Express
November 2015
Objectives
During this presentation, the following objectives will be covered:
  Introduction and definition of the Rockwell Hardness scale, how it is
used to measure and compare different materials
  Review the Implant Maintenance Classification system which helps
decide which instrument materials are most appropriate for what the
clinical situation is presenting
  Describe the various materials currently being used for dental
implant instruments and how they vary, the pro’s and con’s to each
material in regards to how it may affect the dental implant surface
  Show the Rockwell Hardness data of implant maintenance
instruments out on the market in comparison to dental implants
being placed to explain how to select which instrument material is a
better choice
So Many Choices…
Give Me the Hard Data…
Angella M. Fuller, RDH, BA
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November 2015
Find Your “Just Right”
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November 2015
HARDNESS
The quality or state of being hard
a: the cohesion of the particles on the surface of a
mineral as determined by its capacity to scratch
another or be itself scratched — compare mohs'
scale
b: resistance of metal to indentation under a static
load or to scratching a measure of a material’s
resistance to plastic deformation (e.g. a small dent
or scratch)
From Merriam Webster.com
Definition of PLASTIC DEFORMATION
: a permanent deformation or change in shape of a solid body without
fracture under the action of a sustained force <small changes in the
density of crystals due to plastic deformation — Louise R.
Smoluchowski> <plastic flow of crystalline rocks — Journal of Geology>
From Merriam Webster.com
History of Hardness
 Early tests were based on what material
would scratch another material.
 Mohs scale - ranges from 1 for soft
materials like talc to 10 for diamonds.
 Further refinement of testing lead to
quantitative testing such as Rockwell,
Brinell, and Vickers testing.
 These all work by measuring materials
resistance to a known load condition
Angella M. Fuller, RDH, BA
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November 2015
Stanley and Hugh Rockwell
Co-Inventors of the Rockwell Hardness
Tester
Rockwell Scale
  A hardness scale based on indentation hardness of a
material.
  The Rockwell test determines the hardness by
measuring the depth of penetration of an indenter under
a large load compared to the penetration made by a
preload
  There are different scales, denoted by a single letter,
that use different loads or indenters.
  The result is a dimensionless number noted as HRA,
HRB, HRC, etc., where the last letter is the respective
Rockwell scale
From Wikipedia.com
Various Rockwell Scales
]
[2]
Scale
Abbreviation
A
HRA
60 kgf
120° diamond spheroconical†
Tungsten carbide
B
HRB
100 kgf
1⁄ -inch-diameter
16
Aluminium, brass, and
soft steels
C
HRC
150 kgf
120° diamond spheroconical
D
HRD
100 kgf
120° diamond spheroconical
E
HRE
100 kgf
1⁄ -inch-diameter
8
(1.588 mm) steel sphere
(1.588 mm) steel sphere
†Also
Load
Indenter
(1.588 mm) steel sphere
Use
Harder steels >B100
(3.175 mm) steel sphere
F
HRF
60 kgf
1⁄ -inch-diameter
16
G
HRG
150 kgf
1⁄ -inch-diameter
16
called a brale indenter
Angella M. Fuller, RDH, BA
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November 2015
Which Scales Are Most Important for
RDH’s To Evaluate Their Instruments?
  Rockwell C Scale (HRC) is used to compare
metals in general
  Plastic instruments are so much softer than
Titanium, the Rockwell B scale (HRB) is used to
compare it to Titanium accurately
–  The reading of plastic instruments was 11.8 HRB
–  HRB values need to be around 100 to cross over to a
value comparable to Titanium
A Rockwell Hardness Tester, A digital Rockwell
tester, A close-up of the indenter and anvil on a
Rockwell Hardness Tester
Video Demonstrating How
The Machine Works
https://www.youtube.com/watch?feature=player_detailpage&v=G2JGNlIvNC4
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November 2015
Why Is This Important?
 So…how do we use this information to
see if our instruments are safe???
 Obtain the Rockwell hardness value of the
dental implant and compare it to the value
of the implant maintenance instrument
being used
 Which one should be harder than the
other and why???
Rockwell Hardness Data Comparisons
Company
Average HRC
CHART 1: IMPLANTS
Straumann
CAMLOG
Nobel Biocare
31.2-34.1
29.7
31
Bicon
MIS
29.9
34.2
ID Number
Average HRC
CHART 2: TITANIUM INSTRUMENTS
Company A
B
C
31.9
36.2
33.5
D
E
29.5
35.7
Things to Consider
  Implant maintenance instruments should be chosen
based on the best design features to access the parts of
the implant and prosthetic components being cleaned
  Other things to consider when choosing an instrument
and the material of the instrument include:
–  What is the tissue like? Thick, thin, spongy, tight, exudate
–  What is the bone like? Solid or bone loss present, mobility
–  What is the oral hygiene like? Clean or presence of plaque and/or
calculus
–  Where is the implant located? Posterior vs anterior dictates if
longer shanks or slimmer tip designs are best
–  What type of prosthetic is it? Crown, bridge, over-denture bar, etc
–  Is it a roughened or smooth implant abutment/collar?
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November 2015
Implant Maintenance
Classification System
  When health is present
in an ideal relationship
between the peri-implant
tissues and the restored
implant
  Not cleaning any portion of
the implant fixture, just debriding the crown/
prosthesis
  Class I implant maintenance - debridement of
the prosthesis
Implant Maintenance
Classification System
  Probing depths are 4 mm or greater,
some moderate peri-implant soft
tissue recession may be present
  Access to debride the transmucosal
portion of the abutment. The height
of the abutment may vary because
of varying soft tissue heights or
countersinking of the implant in the esthetic zone.
  Class II implant maintenance— debridement of the
prosthesis and the transmucosal portion of the
abutment.
Implant Maintenance
Classification System
  Significant recession or pocket
formation with poor bone exposes the
implant, implant has lost bone support
  Must debride the exposed portion of the
implant fixture, may have threads that
also have to be cleaned
  The exposed coronal aspect of the
implant may have a polished metal collar
or a roughened surface. Roughened surface can be more
plaque retentive than a polished metal collar.
  Class III implant maintenance—debridement of the prosthesis,
the transmucosal portion of the abutment, and the exposed
implant fixture
Hempton, T. Implant Maintenance :Technique and tools for effective debridement of artificial anatomy
Dimensions of Dental Hygiene-Jan 2011-9(1) 58-61
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Hempton Research also notes…
In the Class III maintenance scenario (exposure of the implant)
newer implant designs present an interesting clinical situation.
The concept of preventing scratching of the actual implant
surface may be regarded as contradictory in light of the fact that
a number of commonly used implant systems have eliminated
the polished collar associated with the most coronal aspect of
the implant. These implants have a roughened surface extending
to the most coronal portion of the implant fixture. In the case of
implants with a completely roughened surface, recent evidence
indicates that metal curets may actually reduce implant surface
roughness, making them less plaque retentive
Augthun M, Tinschert J, Huber A. In vitro studies on the effect of cleaning methods on different implant
surfaces. J Periodontol. 1998;69:857-864.
Types of Materials Used for Implant
Maintenance Instruments
Plastic / Resin
  Plastic dental implant instruments can be unfilled or
filled resin.
  Unfilled resin does not have any fillers to reinforce its
shape or stiffness
  Filled resin uses silica, graphite or glass to retain shape
and stiffness
  PLASTEEL: A high grade, unfilled resin that causes the
least amount of alteration to implant abutment surfaces
  Will remove microbial deposits without altering the
surface of the implant, may leave trace plastic particles
embedded in the implant surface
Angella M. Fuller, RDH, BA
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November 2015
Plastic Ultrasonic Tips
  Mann M, Parmar D, Walmsley
AD and Lea SC. Effect of plastic
covered ultrasonic scalers on
titanium implant surfaces.
Clin. Oral Impl. Res. 23, 2012;
76–82
  Plastic-coated scaler probes cause minimal
damage to implant surfaces and have a polishing
action but can leave plastic deposits behind on
the implant surface.
Graphite
 Most common on the market are a fiberreinforced graphite material, more dense
than the plastic/resin material
 The graphite is strong yet slightly flexible,
allowing the tips to access tight areas
effectively and safely
 Graphite can be sharpened unlike the
plastic/resin material
 Is it hard enough to remove calculus?
Titanium
 Medical grade/ commercially pure titanium
material is preferred because of its
biocompatibility
 Tips are thinner than plastic implant scalers,
easier access
 Titanium provides the needed strength to
dislodge calculus and even residual cement
 NOT ALL TITANIUM IS CREATED EQUAL!!!
Angella M. Fuller, RDH, BA
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November 2015
Commercially Pure Titanium Grades
  Grade 1 Titanium - the softest and most ductile
–  It possesses the greatest formability, excellent
corrosion resistance and high impact toughness.
  Grade 2 Titanium - the “workhorse” of the
commercially pure titanium industry
–  Varied usability and wide availability, shares many of
the same qualities as Grade 1 titanium, but it is
slightly stronger. Both are equally corrosion resistant.
This grade possesses good weldability, strength,
ductility and formability.
Commercially Pure Titanium Grades
  Grade 3 is used in applications requiring
moderate strength and major corrosion
resistance. Grade 3 is stronger than Grades 1
and 2, similar in ductility and only slightly less
formable - but it possesses higher mechanicals
than its predecessors.
  Grade 4 Medical Grade Titanium - known as the
strongest of the four grades of commercially
pure titanium. It is also known for its excellent
corrosion resistance, good formability and
weldability.
What’s Wrong With Stainless Steel?
  Stainless Steel instruments and ultrasonic tips leave
scratches and gouges on the titanium surfaces, which
may harbor any subsequent accumulation of biofilm.
Stainless steel is a harder material than titanium, so the
instrument will most likely scratch the abutment.
  General HRC of the implants themselves was around
30-35
  Titanium HRC values range from 23-36
  Plastic instruments aren’t even on the same scale, HRB
of 11-12
  Stainless steel HRC values are generally at 58-65!
Angella M. Fuller, RDH, BA
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RDH CE Evening Express
November 2015
Hardness Conversion Estimate
BrVCoat. Inc.
Stainless Steel Instrument Being
Used On An Implant…
You Can See the Scratch!
Re-visiting the Classifications of
Implant Maintenance
  Based on what parts of the implant are exposed or accessible to
clean, there may be more than one material that is ideal to treat the
area…
  CLASS I – plastic instruments could be used to de-plaque the area
without worry of leaving residual material behind, ultrasonic tips
should be safe as well since no bone loss or exposure
  CLASS II – graphite, ultrasonic instruments, plastic tip ultrasonic
and/or plastic scalers could be used to debride exposed supra and
sub parts of the abutment (polished collar)
  CLASS III – titanium will be the strongest to remove calculus in
threads without scratching, not advised to use plastic as it will shred
on the threads
Angella M. Fuller, RDH, BA
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RDH CE Evening Express
November 2015
Thank You!
Contact Information:
[email protected]
This presentation is supported by American Eagle Instruments Inc.
through an unrestricted educational grant.
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