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  1. 1. Gingival Retraction Techniques for Implants Versus Teeth: Current Status Vincent Bennani, Donald Schwass and Nicholas Chandler J Am Dent Assoc 2008;139;1354-1363 The following resources related to this article are available online at ( this information is current as of January 4, 2011 ): Downloaded from on January 4, 2011 Updated information and services including high-resolution figures, can be found in the online version of this article at: This article appears in the following subject collections: Restoratives Information about obtaining reprints of this article or about permission to reproduce this article in whole or in part can be found at:© 2011 American Dental Association. The sponsor and its products are not endorsed by the ADA.
  2. 2. CLINICAL PRACTICE CRITICAL REVIEWGingival retraction techniques for implantsversus teethCurrent statusVincent Bennani, DDS, PhD; Donald Schwass, BSc, BDS; Nicholas Chandler, BDS, MSc, PhD Downloaded from on January 4, 2011 mplant dentistry has seenI 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 IOrestorative techniques: screw- pared gingival retraction techniques used for T T A N Iretained implant restorations, in implants and teeth. U C A ING EDU 3 Types of Studies Reviewed. The authors RTwhich the fastening screw provides ICLEa solid joint between the restoration searched the literature using article databases Ovidand the implant abutment or MEDLINE up to May 2008, PubMED and Google Scholar (advancedbetween 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, impressionrations, 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 gingivalrestoration 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 newpatients who receive implants for product development are needed.several reasons, including esthetics, Clinical Implications. The use of injectable materials that form anocclusal stability, overcoming angu- expanding matrix to provide gingival retraction offers effective exposurelation 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, forcan 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-implantthroughout 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 oftific documentation of the cement- Otago, 280 Great King St., P.O. Box 647, Dunedin, New Zealand, 9054. Address reprint requests toretained technique compared with Dr. Bennani. Mr. Schwass is a postgraduate student in prosthodontics, Department of Oral Rehabilitation, School ofthat 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 October 2008 Copyright © 2008 American Dental Association. All rights reserved.
  3. 3. CLINICAL PRACTICE CRITICAL REVIEWthe materials used and the techniques followed in gins with a radius less than the contacting probeclinical practice. One question concerns gingival tip.12retraction 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 theplacement while making impressions. Others, architecture of the gingival crevice surroundingsuch as the pickup impression technique, do not natural teeth is different biologically from thatrequire any gingival retraction. For screw- around implants, we wanted to know if conven-retained implant restorations, most systems use tional retraction techniques could be appliedmechanical components (impression copings) that safely to peri-implant tissue. In this article, wecan 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 techniquecannot be used owing to the unique contour of the METHODS Downloaded from on January 4, 2011abutments. Therefore, clinicians must use We conducted a literature search for articlesanother technique such as the conventional crown about gingival retraction techniques used whenand 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-tissueminimum 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 usedbefore making the impression.9,10 Rapid reclosure and the number of articles they generated wereof the sulcus requires that clinicians make the as follows: “gingival retraction” (130), “implantimpression 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 articlessight, which is facilitated by performing gingival by using PubMED and Google Scholar (advancedretraction to expose finish lines. Artifacts caused search).by retraction cord fibers that remain in the sulcus Considering the relative paucity of informationmay affect the accuracy of optical impressions. on this subject, we considered all references to beFifteen percent aluminum chloride in an a relevant contribution. If we had implemented ainjectable kaolin matrix leaves a clean sulcus, more rigorous selection protocol with tighterreducing the influence of artifact-generated study inclusion criteria, we would have had fewerrors.11 However, the powders used when making results.optical impressions to reduce reflectivity andmake tooth surfaces measurable can influence COMPARISON OF PERIDENTAL AND PERI-IMPLANT TISSUEimpression accuracy by increasing tooth surfacethickness.12 There are substantial differences between the Clinicians regard the indirect capture of digi- connective tissue structures surrounding teethtized information as being potentially more accu-rate; however, the way in which clinicians can ABBREVIATION KEY. CAD/CAM: Computer-aidedacquire data is influenced by the thickness of the design/computer-aided manufacturing. CO2: Carbonimpression 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 October 2008 1355 Copyright © 2008 American Dental Association. All rights reserved.
  4. 4. CLINICAL PRACTICE CRITICAL REVIEW 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 Downloaded from on January 4, 2011 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 1356 JADA, Vol. 139 October 2008 Copyright © 2008 American Dental Association. All rights reserved.
  5. 5. CLINICAL PRACTICE CRITICAL REVIEWa tendency to form pockets rather than recede.Thus, a thick biotype is more conducive forimplant placement.14,18GINGIVAL RETRACTION TECHNIQUEWhen making impressions for fixed prostheses,clinicians need to expose, access and isolate theabutment margins. Clinicians can record goodimpressions only if they meet these requirements.The precise reproduction of the abutment pro-vides clinicians with crucial clinical informationthat allows them to fabricate exact-fitting, bio-integrated restorations.19 The aim of gingivalretraction is to atraumatically allow access for theimpression 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. Downloaded from on January 4, 2011material 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 haveorganized periodontal complex surrounding nat- been retracted with medicated cords tend toural teeth provides support for gingival tissues remain open longer. A 0.2-mm sulcular width iswhen they are retracted, mitigating the collapse necessary for there to be sufficient thickness ofof the tissues when the retraction agents are material at the margins of impressions so theyremoved before making the impression. The peri- can withstand tearing or distortion on removal ofimplant fiber structure, however, does not provide the impression.7 The results of another miniaturethe same level of support and is not able to pre- camera study showed that to achieve 0.2-mmvent the collapse of retracted tissues to the same crevicular width, the retraction cords needed toextent, which complicates attempts to success- be in place for four minutes before making thefully make impressions. This is particularly true impression.9 Placing retraction cords for longerin situations in which the depth of sulcus is than this amount of time gained no furthergreater than average, such as when an implant advantage, but placing the retraction cords forhas 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 20around natural teeth when they retract soft tis- seconds after it was removed. Low-viscositysues 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 toforces are gentle since patients’ peri-implant junc- prevent this relapse.22tional epithelium is more fragile. Displacement is a downward movement of the Deformation of gingival tissues during retrac- gingival cuff that is caused by heavy-consistencytion 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 ofment of the free gingival margin that is caused by closely adapted customized impression trays.22the 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 notgo back to its original position. It is influenced by rebound to its original position. The gingivalthe elasticity or memory of the gingival cuff and tissue responds viscoelastically, and recoveryby the rebound forces of adjacent attached gingiva time is much longer than the duration of thethat was compressed during retraction. When deforming force application. If too much traumaclinicians 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 camera determined that the sulci closed Clinicians have adopted techniques that origi- JADA, Vol. 139 October 2008 1357 Copyright © 2008 American Dental Association. All rights reserved.
  6. 6. CLINICAL PRACTICE CRITICAL REVIEW 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 Downloaded from on January 4, 2011 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 connec- tive 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 1358 JADA, Vol. 139 October 2008 Copyright © 2008 American Dental Association. All rights reserved.
  7. 7. CLINICAL PRACTICE CRITICAL REVIEWTABLE 2Gingival retraction techniques and their application to implant dentistry.RETRACTION ADVANTAGES DISADVANTAGES USE INMETHODS IMPLANT DENTISTRYMechanicalCord (may be Inexpensive Painful Yes/No*twisted, knitted Achieves varying degrees of retraction Rapid collapse of sulcus after removalor braided) Can be used with chemical adjuncts Risk of traumatizing epithelial attachmentSingle-cord technique No hemostasisDual-cord technique Placement is time-consuming Risk of sulcus contaminationChemomechanicalChemicals with cordEpinephrine Hemostatic Systemic effects “epinephrine syndrome” No Vasoconstrictive Risk of inflammation of gingival cuff Rebound hyperemia Risk of tissue necrosisSynthetic Hemostatic Rebound hyperemia No Downloaded from on January 4, 2011sympathomimetic Vasoconstrictive Risk of inflammation of gingival cuffagents More effective than epinephrine with Risk of tissue necrosis the absence of systemic effectsAluminum sulphate Hemostasis Offensive taste Yes/Noand Least inflammation of all agents used Risk of sulcus contaminationaluminum potassium with cords Risk of necrosis if in high concentrationsulphate Little sulcus collapse after cord removalAluminum 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 impressionsFerric sulphate Hemostasis Tissue discoloration Yes/No Acidic taste Risk of sulcus contamination Inhibits set of polyvinyl siloxane and polyether impressionsChemicals in aninjectable matrixAluminum chloride Reduced risk of inflammation Inhibits set of polyvinyl siloxane and Yeswith kaolin (injectable form) polyether impressions Nontraumatizing to junctional More expensive epithelium Less effective with very subgingival Hydrophilic margins Ease of placement Painless No adverse effectsInert matrixPolyvinyl 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 effectsSurgicalLaser 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 epitheliumElectrosurgery Efficient precise hemostasis Contraindicated with implant (risk of No arcing) Gingival sulcus too small for two elec- trodes, impractical in implant dentistryRotary 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. Copyright © 2008 American Dental Association. All rights reserved.
  8. 8. CLINICAL PRACTICE CRITICAL REVIEW 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 Downloaded from on January 4, 2011 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 1360 JADA, Vol. 139 October 2008 Copyright © 2008 American Dental Association. All rights reserved.
  9. 9. CLINICAL PRACTICE CRITICAL REVIEWwavelength and waveform characteristics. The Electrosurgery. Clinicians can use electro-use of Nd:YAG lasers is contraindicated near surgery effectively to widen the gingival sulcusimplant surfaces, because they tend to absorb around natural teeth before placing the cord andenergy, 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 aroundthis laser’s wavelength on metal.55 There is also a implants because there is significant risk that thetendency 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 structurearound 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 generatereflected by metal implant surfaces and mini- heat, which may cause osseous or mucosalmally penetrate the soft tissues, so they are rela- necrosis.56tively safe to use. The hemostasis achieved with Rotary curettage. Rotary curettage involves thethe Er:YAG laser, however, is not as effective as use of a high-speed turbine to excise the gingivalthat achieved with the carbon dioxide (CO2) tissue quickly and create a trough around the Downloaded from on January 4, 2011laser.55 margins. For healthy, disease-free tissue around The prime chromophore of the CO2 laser, which natural teeth, rotary curettage has little effect onhas a wavelength of 10,600 nm, is water, and it gingival margin heights if adequate keratinizedreflects off metal surfaces. When used near metal gingiva is present,57 although slight deepening ofimplant 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 atnized fibroblast alignment. This reduces tissue the base of the gingival sulcus surrounding theshrinkage through scarring, which helps preserve implant could lead to an exaggerated response togingival 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 DISCUSSIONobliterated when lasers are used for retraction The mechanical retraction of gingival tissues bypurposes, since clinicians receive virtually no tac- using cords around implant restorations can leadtile 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 aroundbiological seal, the attached gingiva serves as a natural teeth where the junctional epithelium isbarrier that prevents exposure of the implant robust. The forces used in cord placement arebody 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 sulcallasers, but their method of exposing implant mar- epithelium will break down, causing ulcerationsgins is to create a trough by excision rather than with delayed healing. Once patients’ gingivalby 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 oftures 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 contraindicatedcritical, it may not be desirable to create a trough around implants, except in situations in whicharound the margins, as it may have a detrimental patients’ sulcus depths are shallow, their mucosaleffect 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 retractionthey are invasive, thus failing to meet the ideal cords further complicates the situation and mayobjective of a truly conservative technique. lead to increased inflammation of the subsulcular JADA, Vol. 139 October 2008 1361 Copyright © 2008 American Dental Association. All rights reserved.
  10. 10. CLINICAL PRACTICE CRITICAL REVIEW 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 Downloaded from on January 4, 2011 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- 1. Rieder CE. Copings on tooth and implant abutments for super- tion offers clinicians the opportunity to perform structure prostheses. Int J Periodontics Restorative Dent 1990; an atraumatic procedure. There is no risk of lac- 10(6):436-453. 2. Misch CE. Screw-retained versus cement-retained implant-sup- eration when clinicians introduce materials such ported prostheses. Pract Periodontics Aesthet Dent 1995;7(9):15-18. as 15 percent aluminum chloride in a kaolin 3. Bidez MW, Misch CE. Force transfer in implant dentistry: basic concepts and principles. J Oral Implantol 1992;18(3):264-274. matrix into the sulcus surrounding natural teeth. 4. Guichet DL. Load transfer in screw- and cement-retained implant With no damage to the junctional epithelium at fixed partial denture design: proceedings of the fourth International Symposium on Implant Dentistry—focus on esthetics, San Diego, the base of the sulcus or to the sulcus walls, the Calif., January 27 through 29, 1994. 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Int J Prosthodont 2004;17(5):585-589. matrix is not without its limitations. The viscosity 9. Baharav H, Laufer BZ, Langer Y, Cardash HS. The effect of dis- of the injectable matrix limits the force of retrac- placement time on gingival crevice width. Int J Prosthodont 1997;10(3): 248-253. tion offered, and, while this protects the implant 10. Laufer BZ, Baharav H, Langer Y, Cardash HS. The closure of the sulcus from the trauma of overpacking, it may not gingival crevice following gingival retraction for impression making. J Oral Rehabil 1997;24(9):629-635. offer sufficient retraction for situations that are 11. Masek R. Margin isolation for optical impressions and adhesion. unique to implant dentistry in which the Int J Comput Dent 2005;8(1):69-76. 12. Quaas S, Rudolph H, Luthardt RG. Direct mechanical data acqui- relapsing and collapsing forces are important. sition of dental impressions for the manufacturing of CAD/CAM resto- Deeply placed implants often are associated with rations. J Dent 2007;35(12):903-908. 13. Donovan TE, Chee WW. Current concepts in gingival displace- an increased sulcus depth compared with that ment. Dent Clin North Am 2004;48(2):433-444. found around natural teeth; this is reflected by 14. Ericsson I, Lindhe J. Probing depth at implants and teeth: an 1362 JADA, Vol. 139 October 2008 Copyright © 2008 American Dental Association. All rights reserved.
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