1354

Gingival Retraction Techniques for Implants
Versus Teeth: Current Status
Vincent Bennani, Donald Schwass and Nicholas
Chandler
J Am Dent Assoc 2008;139;1354-1363

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CLINICAL PRACTICE CRITICAL REVIEW

Gingival retraction techniques for implants
versus teeth
Current status
Vincent Bennani, DDS, PhD; Donald Schwass, BSc, BDS; Nicholas Chandler, BDS, MSc, PhD

mplant dentistry has seen

I rapid progress in recent years.
Its increased use in the treat-
ment of partially edentulous
ABSTRACT
Background. The authors reviewed and com-
✷
J
A D
A

®
✷

N
CON
patients has led to two

IO
restorative techniques: screw- pared gingival retraction techniques used for

T
T

A
N

I
retained implant restorations, in implants and teeth. U C
A ING EDU 3
Types of Studies Reviewed. The authors RT
which the fastening screw provides ICLE
a solid joint between the restoration searched the literature using article databases Ovid
and the implant abutment or MEDLINE up to May 2008, PubMED and Google Scholar (advanced
between the restoration and the search) and the following search terms: gingival retraction, implant abut-
implant; and cement-retained resto- ment, impressions, cement-retained implant restoration, impression
rations, in which clinicians do not coping, peri-implant tissue, emergence profile and tissue conditioning.
use screws but instead cement the Results. The authors found insufficient evidence relating to gingival
restoration on a machined or cus- displacement techniques for impression making for implant dentistry.
tomized abutment. Gingival retraction techniques and materials are designed primarily for
Cement-retained prostheses are peridental applications; the authors considered their relevance to peri-
the restoration of choice for many implant applications and determined that further research and new
patients who receive implants for product development are needed.
several reasons, including esthetics, Clinical Implications. The use of injectable materials that form an
occlusal stability, overcoming angu- expanding matrix to provide gingival retraction offers effective exposure
lation problems and the fabrication of preparation finish lines and is suitable for conventional impression-
of a passively fitting restoration.1,2 making methods or computer-aided design/computer-aided manufac-
Some investigators have suggested turing digital impressions in many situations. There are, however, limita-
that the intervening cement layer tions with any retraction technique, including injectable matrices, for
can act as a shock absorber and situations in which clinicians place deep implants.
enhance the transfer of load Key Words. Gingival retraction; implant impressions; peri-implant
throughout the prosthesis-implant- tissue; tissue conditioning.
bone system.3,4 JADA 2008;139(10):1354-1363.
There is, however, limited scien-
Dr. Bennani is a senior lecturer, Department of Oral Rehabilitation, School of Dentistry, University of
tific documentation of the cement- Otago, 280 Great King St., P.O. Box 647, Dunedin, New Zealand, 9054. Address reprint requests to
retained technique compared with Dr. Bennani.
Mr. Schwass is a postgraduate student in prosthodontics, Department of Oral Rehabilitation, School of
that for screw-retained technique.5,6
Dentistry, University of Otago, Dunedin, New Zealand.
The quest for predictable long-term Dr. Chandler is an associate professor, Department of Oral Rehabilitation, School of Dentistry, Univer-
results has raised questions about sity of Otago, Dunedin, New Zealand.

1354 JADA, Vol. 139 http://jada.ada.org October 2008
Copyright © 2008 American Dental Association. All rights reserved.


the materials used and the techniques followed in gins with a radius less than the contacting probe
clinical practice. One question concerns gingival tip.12
retraction techniques and their outcomes in Donovan and Chee13 described a variety of gin-
implant treatment. gival displacement techniques, but we found no
Several impression techniques are used in articles that specifically reviewed gingival retrac-
implant dentistry, and some require gingival dis- tion techniques in implant dentistry. Since the
placement while making impressions. Others, architecture of the gingival crevice surrounding
such as the pickup impression technique, do not natural teeth is different biologically from that
require any gingival retraction. For screw- around implants, we wanted to know if conven-
retained implant restorations, most systems use tional retraction techniques could be applied
mechanical components (impression copings) that safely to peri-implant tissue. In this article, we
can be adapted accurately and directly to the fix- review the advantages and disadvantages of dif-
ture head on the abutment shoulder. With ferent gingival retraction techniques on peri-
cement-retained prostheses that use customized implant and peridental tissues.
abutments, the pickup impression technique
cannot be used owing to the unique contour of the METHODS

abutments. Therefore, clinicians must use We conducted a literature search for articles
another technique such as the conventional crown about gingival retraction techniques used when
and bridge impression or optical impression. making impressions of implant restorations. We
To ensure accuracy with polyvinyl siloxane noted that there was no literature on this subject,
impression materials, clinicians must maintain a so we widened our search to include soft-tissue
minimum bulk of 0.2-millimeter thickness in the retraction techniques applicable to natural teeth.
sulcus area,7,8 which they can achieve by We conducted the search using Ovid MED-
retracting the gingiva for at least four minutes LINE up to May 2008. The key words we used
before making the impression.9,10 Rapid reclosure and the number of articles they generated were
of the sulcus requires that clinicians make the as follows: “gingival retraction” (130), “implant
impression immediately after removing the abutment” (237), “impressions” (7,242), “cement-
retraction material.7,10 retained implant restoration” (one), “impression
Larger sulcus spaces than necessary for con- coping” (22), “peri-implant tissue” (141), “emer-
ventional crown and bridge impression tech- gence profile” (76) and “tissue conditioning” (326).
niques are needed when making digital computer- Combinations of key words that yielded zero arti-
aided design/computer-aided manufacturing cles were “impressions” plus “cement retained
(CAD/CAM) impressions to ensure accurate implant restoration” and “peri-implant tissue”
recording of finishing lines. plus “emergence profile” plus “tissue condi-
Direct optical impressions are limited to line of tioning.” We searched further for relevant articles
sight, which is facilitated by performing gingival by using PubMED and Google Scholar (advanced
retraction to expose finish lines. Artifacts caused search).
by retraction cord fibers that remain in the sulcus Considering the relative paucity of information
may affect the accuracy of optical impressions. on this subject, we considered all references to be
Fifteen percent aluminum chloride in an a relevant contribution. If we had implemented a
injectable kaolin matrix leaves a clean sulcus, more rigorous selection protocol with tighter
reducing the influence of artifact-generated study inclusion criteria, we would have had few
errors.11 However, the powders used when making results.
optical impressions to reduce reflectivity and
make tooth surfaces measurable can influence COMPARISON OF PERIDENTAL AND
PERI-IMPLANT TISSUE
impression accuracy by increasing tooth surface
thickness.12 There are substantial differences between the
Clinicians regard the indirect capture of digi- connective tissue structures surrounding teeth
tized information as being potentially more accu-
rate; however, the way in which clinicians can ABBREVIATION KEY. CAD/CAM: Computer-aided
acquire data is influenced by the thickness of the design/computer-aided manufacturing. CO2: Carbon
impression material in the sulcus area.11,12 Signifi- dioxide. Er:YAG: Erbium:yttrium-aluminum-garnet.
cant errors can result from thin impression mar- Nd:YAG: Neodymium:yttrium-aluminum-garnet.

JADA, Vol. 139 http://jada.ada.org October 2008 1355


TABLE 1 teeth.17
Comparison of peridental and Peri-implant mucosa consists of circumferen-
tially running fiber bundles and fibers that run
peri-implant tissues. longitudinally to the implant surface. Most con-
PERIDENTAL TISSUE PERI-IMPLANT TISSUE nective tissue fibers that surround smooth
Free gingival margin Free gingival margin with implants run parallel to the implant surface. The
with buccal keratinized buccal keratinized epithe-
epithelium lium
use of rougher implant surfaces encourages the
attachment of fibrils to the implant surface,
Gingival sulcus apically Gingival sulcus apically
limited by the junctional limited by the junctional affecting the orientation of fibers adjacent to
epithelium epithelium implants at varying angles.15,16 The junctional
Keratinized epithelium No keratinized epithelium is longer adjacent to machined
at the base of gingival epithelium at the base implant surfaces (a mean of 2.9 mm) than it is to
sulcus of gingival sulcus
acid etch–conditioned implant surfaces (a mean of
Junctional epithelium Junctional epithelium
adherent, less permeable, poorly adherent, more 1.4 mm) or oxidized surfaces (a mean of 1.6 mm).15
high regenerative permeable, low The junctional epithelium associated with nat-
capacity regenerative capacity
ural teeth has a high rate of cell turnover, which
Cementum No cementum

occurs rapidly during the wound healing that
Gingival fibers inserting Gingival fibers running takes place after penetration by a dental probe or
perpendicularly in the parallel to the implant
cementum collar while recovering from infection.17 The rate of junc-
Biological width of at Biological width of 2.5
tional epithelium cell turnover is twice that of
least 2.04 millimeters mm ± 0.5 mm* oral gingival epithelium. At the base of the
Periodontal ligament No periodontal ligament sulcus, the rate of exfoliation is as much as 50
No direct contact Direct contact of implant
times that of oral gingival epithelium, which, in
between tooth and bone to bone effect, hinders bacterial colonization of the sulcus.
* As shown in Ericsson and Lindhe.14 When the junctional epithelium that surrounds
implants is exposed to
trauma (such as during
gingival retraction pro-
cedures), it is at greater
risk of experiencing
penetration damage
than is the more robust
sulcus of natural teeth.
Pressure that is applied
when clinicians apply
retraction materials
into the sulcus may
cause considerable dis-
comfort in patients; this
is particularly true for
patients with more
Figure 1. Comparison of peridental biological width and peri-implant biological width. vulnerable implant
mm: Millimeters.
situations.
and implants that affect the robustness of gin- Another consideration that has a bearing on
gival tissues (Table 114 and Figure 1). the ability of epithelial tissues to withstand
Peri-implant mucosa lacks keratinized epithe- chemomechanical manipulative procedures is the
lium at the base of the sulcus, which forms the influence of the natural soft tissue biotype. In
junctional epithelium and has a hemidesmosomal tissue hierarchy, teeth act as protagonists fol-
attachment and internal basal lamina in the lowed by soft tissue and bone topography. Clini-
lower regions of the interface.15,16 It adheres cians associate a thin periodontal biotype with
poorly to implant surfaces, is more permeable and fragility that requires delicate management to
has a lower capacity for proliferation and regener- avoid recession owing to tissue damage. Thick
ation than does the junctional epithelium around fibrotic biotypes are more resilient, and they have



a tendency to form pockets rather than recede.
Thus, a thick biotype is more conducive for
implant placement.14,18
GINGIVAL RETRACTION TECHNIQUE
When making impressions for fixed prostheses,
clinicians need to expose, access and isolate the
abutment margins. Clinicians can record good
impressions only if they meet these requirements.
The precise reproduction of the abutment pro-
vides clinicians with crucial clinical information
that allows them to fabricate exact-fitting, bio-
integrated restorations.19 The aim of gingival
retraction is to atraumatically allow access for the
impression material beyond the abutment mar-
Figure 2. Force involved with retraction of peridental and peri-
gins and to create space so that the impression implant tissues.

material is sufficiently thick so as to be tear-resis-
tant.20 In peridental tissue, the fiber-rich, highly within one minute of removal.10 Sulci that have
organized periodontal complex surrounding nat- been retracted with medicated cords tend to
ural teeth provides support for gingival tissues remain open longer. A 0.2-mm sulcular width is
when they are retracted, mitigating the collapse necessary for there to be sufficient thickness of
of the tissues when the retraction agents are material at the margins of impressions so they
removed before making the impression. The peri- can withstand tearing or distortion on removal of
implant fiber structure, however, does not provide the impression.7 The results of another miniature
the same level of support and is not able to pre- camera study showed that to achieve 0.2-mm
vent the collapse of retracted tissues to the same crevicular width, the retraction cords needed to
extent, which complicates attempts to success- be in place for four minutes before making the
fully make impressions. This is particularly true impression.9 Placing retraction cords for longer
in situations in which the depth of sulcus is than this amount of time gained no further
greater than average, such as when an implant advantage, but placing the retraction cords for
has been placed deeply. less time caused a significant effect. For example,
Clinicians prefer that patients have a greater if the clinician placed the cord for only two min-
degree of soft-tissue support than that found utes, the sulcus width closed to 0.1 mm within 20
around natural teeth when they retract soft tis- seconds after it was removed. Low-viscosity
sues surrounding implants. Yet at the same time, impression materials such as light-bodied “wash”
clinicians need to ensure that the retraction type materials do not provide sufficient support to
forces are gentle since patients’ peri-implant junc- prevent this relapse.22
tional epithelium is more fragile. Displacement is a downward movement of the
Deformation of gingival tissues during retrac- gingival cuff that is caused by heavy-consistency
tion and impression procedures involves four impression material bearing down on unsup-
forces: retraction, relapse, displacement and col- ported retracted gingival tissues.
lapse21 (Figure 2). Collapse is the tendency of the gingival cuff to
Retraction is the downward and outward move- flatten under forces associated with the use of
ment of the free gingival margin that is caused by closely adapted customized impression trays.22
the retraction material and the technique used. Depending on the amount and duration of
Relapse is the tendency of the gingival cuff to these forces, the gingival tissue may or may not
go back to its original position. It is influenced by rebound to its original position. The gingival
the elasticity or memory of the gingival cuff and tissue responds viscoelastically, and recovery
by the rebound forces of adjacent attached gingiva time is much longer than the duration of the
that was compressed during retraction. When deforming force application. If too much trauma
clinicians removed plain mechanical retraction occurs and if the gingival tissue is too thin, irre-
cords, an inspection of the sulci using a miniature versible alteration will take place.
video camera determined that the sulci closed Clinicians have adopted techniques that origi-



nally were designed for natural teeth for use in foreign body reactions and exacerbating inflam-
implant restoration situations despite significant mation.27 Healing of the sulcus can take seven to
differences between the tooth biosystem and the 10 days.26,28 Use of minimal force is necessary
implant biosystem. Techniques that clinicians when packing cords to protect Sharpey fibers,29
have refined to work well for teeth may not and application of excessive force is inappropriate
address the challenges faced by clinicians in because it may cause crevicular bleeding, gingival
implant dentistry. The following sections review inflammation30 and shrinkage of marginal
the available retraction techniques for natural tissues.31
teeth and their potential application for implant Clinicians may place untreated plain cord
restorations (Table 2). safely in the sulcus for periods of five to 30 min-
Mechanical retraction. Cord. Clinicians utes,26 but the pressure of cords alone will not
place retraction cords by using cord-packing control sulcular hemorrhage.25 On removal, plain
instruments; however, many commonly used cords are associated with bleeding in more than
hand instruments (such as the Hollenbach carver 50 percent of situations, although wetting the
tip) were not designed for this application. The cords before removal may help control the
forces generated by pointed or wedge-shaped bleeding.32

instrument tips may be traumatic to the rela- Clinicians should question the use of cords
tively fragile junctional epithelium around around implants since the junctional epithelium
implants, whereas gingival tissues may be more is not as adherent, is more permeable and has a
forgiving of this type of force. Some manufac- lower regenerative capacity than the junctional
turers make purpose-designed packing devices epithelium around teeth.
that have smooth, nonserrated circular heads Chemomechanical retraction. Chemicals
that can be used to place and compress twisted with cord. Epinephrine commonly is used to med-
cord with a sliding motion. Other manufacturers icate retraction cords since it provides effective
make devices with serrated circular heads for use vasoconstriction and hemostasis during retrac-
with braided cords. The thin edges of these ser- tion.33 It is, however, associated with significant
rated circular heads sink into the braided cord, local and systemic side effects, which investiga-
and the fine serrations keep it from slipping off tors have reported occurring during 33 percent of
and cutting the gingival attachment. There is no applications.24 Absorption at the sulcus interface
literature describing the use of cord-packing is dependent on patients’ gingival health.34
instruments, and the forces involved with cord Healthy gingiva acts, to some extent, as a barrier
placement remain undetermined. to absorption of epinephrine.35 This may be why
Single-cord versus dual-cord technique. Retrac- the theoretical overdose levels are not observed
tion cords were developed for use with natural clinically. Absorption varies with the degree of
teeth. They provide more effective control of gin- vascular bed exposure, the length of cord used,
gival hemorrhage and exudate when used in con- the concentration of cord impregnation and the
junction with medicaments than when used with length of application time.36 Clinicians should
no medicaments. The use of a single retraction avoid applying high concentrations of epinephrine
cord often provides inadequate gingival retrac- to large areas of lacerated or abraded gingival tis-
tion. The dual-cord technique in which the first sues.37 Patients who are susceptible to the effects
cord remains in the sulcus reduces the tendency of epinephrine may develop “epinephrine syn-
for the gingival cuff to recoil and partially dis- drome,” which includes tachycardia, rapid respi-
place the setting impression material.23 Results ration, increased blood pressure, anxiety and
from one survey showed that 98 percent of postoperative depression.34,36
prosthodontists use cords, with 48 percent using A number of alternatives to epinephrine are
a dual-cord technique and 44 percent using a used clinically, with varying benefits and draw-
single-cord technique.24 backs. Synthetic sympathomimetic agents that
Placement of retraction cords can cause injury mimic the actions of epinephrine are more effec-
to the sulcular epithelium and underlying connective and safer than epinphrine.38
tive tissues,25 as shown by the results of experi- Aluminum sulfate and aluminum potassium
ments involving dogs’ teeth.26 The filaments or sulphate act by precipitating tissue proteins with
fibers of conventional cords also may cause tissue contraction, inhibiting transcapillary move-
residual contamination of sulcal wounds, creating ment of plasma proteins and arresting capillary



TABLE 2

Gingival retraction techniques and their application to implant dentistry.
RETRACTION ADVANTAGES DISADVANTAGES USE IN
METHODS IMPLANT
DENTISTRY
Mechanical
Cord (may be Inexpensive Painful Yes/No*
twisted, knitted Achieves varying degrees of retraction Rapid collapse of sulcus after removal
or braided) Can be used with chemical adjuncts Risk of traumatizing epithelial attachment
Single-cord technique No hemostasis
Dual-cord technique Placement is time-consuming
Risk of sulcus contamination
Chemomechanical
Chemicals with cord
Epinephrine Hemostatic Systemic effects “epinephrine syndrome” No
Vasoconstrictive Risk of inflammation of gingival cuff
Rebound hyperemia
Risk of tissue necrosis
Synthetic Hemostatic Rebound hyperemia No

sympathomimetic Vasoconstrictive Risk of inflammation of gingival cuff
agents More effective than epinephrine with Risk of tissue necrosis
the absence of systemic effects
Aluminum sulphate Hemostasis Offensive taste Yes/No
and Least inflammation of all agents used Risk of sulcus contamination
aluminum potassium with cords Risk of necrosis if in high concentration
sulphate Little sulcus collapse after cord removal
Aluminum chloride No systemic effects Less vasoconstriction than epinephrine Yes/No
Least irritating of all chemicals Risk of sulcus contamination
Hemostasis Modifies surface detail reproduction
Little sulcus collapse after cord removal Inhibits set of polyvinyl siloxane and
polyether impressions
Ferric sulphate Hemostasis Tissue discoloration Yes/No
Acidic taste
Risk of sulcus contamination
Inhibits set of polyvinyl siloxane and
polyether impressions
Chemicals in an
injectable matrix
Aluminum chloride Reduced risk of inflammation Inhibits set of polyvinyl siloxane and Yes
with kaolin (injectable form) polyether impressions
Nontraumatizing to junctional More expensive
epithelium Less effective with very subgingival
Hydrophilic margins
Ease of placement
Painless
No adverse effects
Inert matrix
Polyvinyl siloxane No risk of inflammation or irritation Limited capacity for hemostasis (no active Yes
Nontraumatizing chemistry)
Ease of placement Less effective with subgingival margins
Painless
No adverse effects
Surgical
Laser Excellent hemostasis–carbon dioxide Neodymium:yttrium-aluminum-garnet Yes/No
(CO2) laser safe for implants as laser contraindicated with implants
reflected by metal Erbium:yttrium-aluminum-garnet laser
Reduced tissue shrinkage reflected by metal but not as good at
Relatively painless hemostasis as CO2 laser
Sterilizes sulcus CO2 laser provides no tactile feedback,
leading to risk of damage to junctional
epithelium
Electrosurgery Efficient precise hemostasis Contraindicated with implant (risk of No
arcing)
Gingival sulcus too small for two elec-
trodes, impractical in implant dentistry
Rotary curettage Fast Causes considerable hemorrhage No
Ability to reduce excessive tissue Contraindicated with implants
Ability to recontour gingival outline High risk of the bur damaging the implant
surface
Risk of tissue retraction exposing implant
threads
High risk of traumatizing the epithelial
attachment
* Yes/No: Method could be used but is not recommended.



bleeding.39 Both are hemostatic and retractive, effectiveness in reducing the flow of sulcular exu-
which causes minimal postoperative inflamma- date is similar to that of epinephrine-soaked
tion at therapeutic concentrations,33 although con- cords.49
centrated aluminum potassium sulphate solu- The use of 15 percent aluminum chloride in an
tions can cause severe inflammation and tissue injectable kaolin matrix is effective.50 It also is
necrosis.40 safe, with the results of one study showing no
The action of aluminum chloride is similar to reports of adverse effects.51 Gingival recession
that of aluminum sulfate, which is an astringent associated with an injection of aluminum chloride
that causes precipitation of tissue proteins29 but into the gingival sulcus is almost undetectable.52
less vasoconstriction than epinephrine.35 Alu- The injectable matrix is hydrophilic and can be
minum chloride is the least irritating of the flushed away relatively easily from the gingival
medicaments used for impregnating retraction crevice.46 As with any foreign materials intro-
cords,41 but it disturbs the setting of polyvinyl duced into the oral cavity, there remains a small
siloxane impression materials.42 risk of residues’ persisting in the gingival crevice.
Aluminum potassium sulphate– and aluminum The viscosity of the injectable matrix may not be
chloride–medicated cords are more effective in enough to provide sufficient retraction for deeper

keeping the sulcus open after clinicians remove subgingival preparations,53 and aluminum chlo-
the cord (10-20 percent of original opening eight ride can inhibit the set of polyether and polyvinyl
minutes after the cord is removed) than are siloxane materials if clinicians do not rinse it
epinephrine-medicated cords (50 percent closure away properly before making impressions.
of sulcus observed over a similar time).10 After 12 The delivery of chemicals via an injectable
minutes, only sulci packed with aluminum chlo- matrix shows promise for peri-implant tissue
ride remained open at 80 percent of the original retraction, because it preserves the gingival tis-
space created.10 sues with no risk of lacerating or inflaming the
Owing to its iron content, ferric sulfate stains junctional epithelium. In patients who have
gingival tissues a yellow-brown to black color for deeply placed implants with subgingival margins,
several days after a clinician has used it as a however, its value may be somewhat limited by
retraction agent.20 The accuracy of surface detail the extent to which such matrices are able to
reproduction during impressions can be modified retract effectively.
by ferric sulfate, as it disturbs the setting reac- An inert matrix. A polyvinyl siloxane material
tion of polyvinyl siloxanes. Thus, it is important for gingival retraction was introduced in 2005. It
for clinicians to remove all traces of medicament works by generating hydrogen, causing expansion
from the tissues carefully before recording the of the material against the sulcus walls during
impressions.42 setting. The manufacturer has reported advan-
The two main drawbacks of using chemicals tages including gentle placement without need for
with retraction cords are the occurrence of local anesthetic, visibility in the sulcus due to its
rebound hyperemia that often occurs after cord bright color, ease of removal and absence of the
removal, which affects how effectively clinicians need for hemostatic medicaments. Potential
can make impressions,43,44 and inflammatory reac- drawbacks are that it may not improve the speed
tions induced by these chemicals, which can affect or quality of retraction obtained and that it likely
the subepithelial connective tissue.45 When clini- is less effective with subgingival margins. Clini-
cians consider all of these factors, they may ques- cians place deep implants with subgingival mar-
tion whether retraction cords are appropriate for gins relatively frequently since implant place-
use around implants, given the vulnerability of ment is dictated largely by the location of
the junctional epithelium. available bone.
Chemicals in an injectable matrix. Injecting 15 Surgical retraction. Lasers. Compared with
percent aluminum chloride in a kaolin matrix other retraction techniques, diode lasers with a
opens the sulcus, providing significant mechan- wavelength of 980 nanometers and neodymium:
ical retraction.46,47 When compared with having a yttrium-aluminum-garnet (Nd:YAG) lasers with a
cord packed into the sulcus, an injection of 15 per- wavelength of 1,064 nm are less aggressive, cause
cent aluminum chloride in a kaolin matrix less bleeding and result in less recession around
resulted in less pain for patients and was easier natural teeth (2.2 percent versus 10.0 percent).54
and quicker to administer.48 Furthermore, its Lasers’ properties largely depend on their



wavelength and waveform characteristics. The Electrosurgery. Clinicians can use electro-
use of Nd:YAG lasers is contraindicated near surgery effectively to widen the gingival sulcus
implant surfaces, because they tend to absorb around natural teeth before placing the cord and
energy, which causes them to heat up and to provide hemostasis by coagulation. However,
transmit the heat to bone, owing to the effects of electrosurgery is not recommended around
this laser’s wavelength on metal.55 There is also a implants because there is significant risk that the
tendency for Nd:YAG lasers to damage the fragile contacting electrode may arc by conducting elec-
subjunctional epithelium at the sulcus base tric current though the metal implant structure
around implants. to the bone rather than via the more dispersive
Erbium:yttrium-aluminum-garnet (Er:YAG) gingival tissue pathway. The concentrated elec-
lasers with a wavelength of 2,940 nm are trical current at the tip of electrodes can generate
reflected by metal implant surfaces and mini- heat, which may cause osseous or mucosal
mally penetrate the soft tissues, so they are rela- necrosis.56
tively safe to use. The hemostasis achieved with Rotary curettage. Rotary curettage involves the
the Er:YAG laser, however, is not as effective as use of a high-speed turbine to excise the gingival
that achieved with the carbon dioxide (CO2) tissue quickly and create a trough around the

laser.55 margins. For healthy, disease-free tissue around
The prime chromophore of the CO2 laser, which natural teeth, rotary curettage has little effect on
has a wavelength of 10,600 nm, is water, and it gingival margin heights if adequate keratinized
reflects off metal surfaces. When used near metal gingiva is present,57 although slight deepening of
implant surfaces, CO2 lasers absorb little energy, the sulcus may result.58 However, rotary curet-
with only small temperature increases (< 3oC) and tage is inappropriate for use around implant res-
minimal collateral damage. CO2 lasers do not torations because of poor tactile control when cut-
alter the structure of the implant surface.55 ting soft tissue, which could lead to bur contact
Surgical wounds created by lasers heal by sec- damage to the implant surface and overinstru-
ondary intention, and incision lines show disorga- mentation. The absence of keratinized gingiva at
nized fibroblast alignment. This reduces tissue the base of the gingival sulcus surrounding the
shrinkage through scarring, which helps preserve implant could lead to an exaggerated response to
gingival margin heights.31 rotary curettage, including deepening of the
Visualizing the action of laser beams is diffi- sulcus and gross recession.
cult, owing to the plume of coolant water. So,
there is the potential for attached gingiva to be DISCUSSION
obliterated when lasers are used for retraction The mechanical retraction of gingival tissues by
purposes, since clinicians receive virtually no tac- using cords around implant restorations can lead
tile feedback. Although there is a hemidesmo- to ulceration of the junctional epithelium. Retrac-
somal attachment around implants that creates a tion cords were developed for application around
biological seal, the attached gingiva serves as a natural teeth where the junctional epithelium is
barrier that prevents exposure of the implant robust. The forces used in cord placement are
body over time through recession. likely to exceed peri-implant tissues’ capacity to
There are many advantages to using CO2 resist them. The resulting laceration of the sulcal
lasers, but their method of exposing implant mar- epithelium will break down, causing ulcerations
gins is to create a trough by excision rather than with delayed healing. Once patients’ gingival
by displacing soft tissue. Therefore, their use may epithelial structure is damaged, there is signifi-
not be practical around deeply placed implant fix- cant risk of permanent recession and loss of
tures where a large defect could result. In addi- attachment developing. Thus, the use of mechan-
tion, in anterior applications in which esthetics is ical retraction with cords may be contraindicated
critical, it may not be desirable to create a trough around implants, except in situations in which
around the margins, as it may have a detrimental patients’ sulcus depths are shallow, their mucosal
effect on patients’ appearances. health is impeccable and a robust, thick perio-
Although CO2 lasers may be significantly dontal biotype is present.
useful in some implant impression situations, The addition of chemical adjuncts to retraction
they are invasive, thus failing to meet the ideal cords further complicates the situation and may
objective of a truly conservative technique. lead to increased inflammation of the subsulcular



tissues. If the delicate junctional epithelium the greater “biologic width” that is observed. It is
around the implant restoration becomes damaged not always possible to avoid deep placement of
during cord placement, the lacerated sulcus pro- implants as this is dictated by patients’ bone
vides reduced protection against the penetration morphology.
of chemicals into deeper subepithelial cell layers Although injectable matrices are promising as
and against systemic dissemination when the a gingival retraction technique for implant situa-
vascular bed is exposed. All chemical agents used tions, further development is needed. Compared
for gingival retraction are irritants, and study with research on implant fixtures, there is rela-
results demonstrate their adverse effects on peri- tively little research to guide clinicians regarding
dental tissues.26,32,36,37,40,51 Little is known about the how to restore implants59 and about which gin-
effects of these same chemicals when they are gival retraction techniques to use around implant
placed into peri-implant tissues. abutments.
Clinicians often choose to perform surgical pro- In the meantime, the use of techniques devel-
cedures because they are able to, the procedure oped by clinicians for natural teeth will continue.
can be performed rapidly and hemostasis is Further research exploring the uniqueness of the
achievable. Surgical retraction procedures, how- implant restoration situation and investigating

ever, are destructive and involve excision of the effect of these conventional techniques on the
tissue. This may be acceptable around natural peri-implant tissue is needed.
teeth, as the results of studies have supported
using electrosurgery, lasers and rotary curet- CONCLUSION
tage.54,56-58 Evidence does not support the use of The literature concerning gingival retraction for
such destructive procedures in the implant situa- impressions in fixed prosthodontics is extensive.
tion.31,55 Peri-implant mucosa does not have the By contrast, little has been published about the
same capacity for regeneration as peridental challenges presented by the unique anatomy sur-
mucosa. The correct use of lasers with appro- rounding implants. As implants become main-
priate wavelengths may be applicable in some, stream treatments for tooth loss, this topic will
but not all, implant situations during retraction warrant further research.
and when making impressions. Disclosures. None of the authors reported any disclosures.
Using an injectable matrix for gingival retrac-
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