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461

Use of Er:YAG Laser to Decontaminate Infected
Dental Implant Surface in Preparation for
Reestablishment of Bone-to-Implant Contact
Myron Nevins, DDS1
Marc L. Nevins, DMD, MMSc2
Atsuhiko Yamamoto, DDS, PhD3
Toshiaki Yoshino, DDS, PhD4/Yoshihiro Ono, DDS5
Chin-Wei (Jeff) Wang, DDS6/David M. Kim, DDS, DMSc7
The prevalence of peri-implantitis is of concern to all clinicians participating in
implant dentistry. Peri-implant inflammation results in the loss of supportingbone for the implant that may or may not be accompanied by bleeding on
probing and suppuration. Early diagnosis and intervention are mandated, butthere is a paucity of evidence leading to the most effective therapy. There isagreement that one of the challenges in surgically treating peri-implant defects isthe process of cleaning and decontaminating the implant surface, which may becontaminated by bacterial aggregates. This preclinical canine study investigates
the erbium:yttrium-aluminum-garnet laser to decontaminate the complex roughsurface of the implant by stripping the contaminated oxide layer for inductionof hard and soft tissue adaptation to a compromised or failing implant. The
results provide evidence of new bone-to-implant contact established at alevel representative of the size of the defects. The soft tissues contain little
or no evidence of inflammation, which can be interpreted as an arrest of thedisease progression process. The results can be translated to a treatment goalof stabilizing the prognosis of an implant that has been compromised. (Int J
Periodontics Restorative Dent 2014;34:461–466. doi: 10.11607/prd.2192)

Associate Clinical Professor; Division of Periodontology; Department of Oral Medicine,
Infection and Immunity; Harvard School of Dental Medicine; Boston, Massachusetts, USA.
2Assistant Clinical Professor; Division of Periodontology; Department of Oral Medicine,
Infection and Immunity; Harvard School of Dental Medicine; Boston, Massachusetts, USA.
3Lecturer, Department of Prosthodontics, Division of Oral Functional Science andRehabilitation, Asahi University School of Dentistry, Gifu, Japan.
4Lecturer, The Japan Institute for Advanced Dental Studies, Tokyo, Japan.
5Director, The Japan Institute for Advanced Dental Studies, Osaka, Japan.
6Postdoctoral Research Fellow; Division of Periodontology; Department of Oral Medicine,
Infection and Immunity; Harvard School of Dental Medicine; Boston, Massachusetts, USA.
7Associate Professor; Division of Periodontology; Department of Oral Medicine, Infection
and Immunity; Harvard School of Dental Medicine; Boston, Massachusetts, USA.
1Correspondence to: Dr Myron Nevins, 90 Humphrey Street, Swampscott, MA;
fax: 781-598-8050; email: nevinsperimp@aol.com.
©2014 by Quintessence Publishing Co Inc.

Implant replacement of the naturaldentition has been incorporated into
dental treatment planning as theresult of many successful prospective and retrospective reports. It isrealistic to anticipate some problems
during healing following any treatment regimen, and peri-implantitis
has surfaced as a relatively frequently encountered adverse result.1–3
It is understood to be a chronic inflammatory invasion of the soft andhard tissues into which the implantis encased and results in the loss ofalveolar support or bone-to-implantcontact (BIC).1–7
This presents a disappointing discovery for the patient andrequires an important decision.
If the implant is no longer integrated, it must be removed, butwhen stable, most patients would
prefer a treatment regimen withan endpoint goal of preserving theimplant-supported restoration. Of
course, the length of the implant
and the degree of bone loss influence this decision. The literatureis replete with case reports proposing protocols aimed at resolving the microbial contamination of
the implant surface and offering a

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variety of regenerative efforts, butthere is a paucity of evidence thatwould establish a reliable therapeutic approach.8–12 The obvious
impediment to regenerative therapy is the decontamination of theimplant surface now that most contemporary implants have a roughsurface to promote osseointegration. Initial reports demonstratethat the erbium:yttrium-aluminumgarnet (Er:YAG) laser will remove
the microbial infiltrated oxide layer
without deforming the implant or
damaging the supporting bone.13
This then provides a clean surface
to construct new BIC and enable
the implant to continue to support
the prosthesis.
The objectives of this investigation were to:were selected for the study. They
were observed for 14 days for acclimation to their surroundings andthen divided into three treatmentgroups:••1. Determine the Er:YAG
laser’s ability to treat periimplantitis by stripping thecontaminated titanium oxide
layer to promote induction ofosseointegration
2. Study the hard and soft tissue
adaption to a previously
diseased implant surface•

Method and materials
This was a prospective preclinicalstudy investigating the use of the
Er:YAG laser to decontaminate thesurface of a compromised dental
implant with a rough surface. The
study protocol was approved by
the Institutional Animal Care and
Use Committee at PARF in Massachusetts, USA. Six foxhounds
weighing approximately 25 kgGroup A (2 animals): Premolars(P2 to P4) and the first molar(M1) were extracted, and theedentulous ridge was allowed
to heal for 60 days. Implants
were placed, combined withthe creation of infrabony
defects, resembling bone loss
that accompanies peri-implantitis.13 Laser decontaminationin addition to a bone grafting
procedure was planned forthis group.
Group B (3 animals): Premolars(P2 to P4) and the first molar(M1) were extracted, dental
implants were immediately
placed into extraction sockets,and the areas surrounding theimplants were prevented fromhaving spontaneous bone fill,thus creating infrabony defects. Laser decontaminationin addition to a bone grafting
procedure was planned forthis group.
Group C (1 animal, control):
Similar to group A, except nolaser treatment was rendered
to treat the contaminateddental implant surface.

All surgical procedures were
performed under general and local anesthesia in sterile conditions.
Initial intramuscular administrationof xylazine hydrochloride (2.2 mg/kg) and tiletamine hydrochloride/zolazepam hydrochloride (10 mg/kg) was followed by inhalation of
1.5% to 2% isoflurane as a generalanesthesia for the duration of theprocedure. Local anesthesia (2%lidocaine with 1:100,000 epinephrine) was provided at the surgicalsites.
For groups A and C, dental implants were placed after 60 days
with intentional infrabony defects
filled with retraction cord (Ultrapak,
Ultradent) to interfere with healing (Figs 1a and 1b). The group B
animals received implants placedin the extraction wounds, and thespace surrounding the implants received retraction cord to preventbone regeneration (Figs 2a and 2b).
The implants (Brånemark System
Mk III Groovy RP 3.75 × 10 mm,
Nobel Biocare) were placed under
the same surgical conditions as thetooth extractions. A total of four
implants were inserted into eachanimal (two on each side) according to a randomized distribution
pattern generated for each animal
before the surgery. The implant
osteotomy was performed withtorque reduction rotary instruments
using sterile saline solution with an
insertion device and hand ratchet
according to the manufacturer’s
guidelines. The flaps were adapted
for tension-free wound closure withinterrupted and horizontal mattresssutures. The animals received thestandard postsurgical infection andpain control consisting of intramuscularly administered cefazolin sodium (20 mg/kg) and buprenorphine
HCL (0.02 mg/kg). Both groups
were then observed for 60 days, atwhich time the bone defects weretreated.

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463
Fig 1a (left) In group A, dental implants
were placed 60 days after extraction, andintentional infrabony defects were createdadjacent to the implants.
Fig 1b (right) The infrabony defects werefilled with retraction cord to interfere withnormal bone healing.

Fig 2a (left) For group B, dental implants
were immediately placed into the extraction wounds.
Fig 2b (right) The space surrounding theimplants received retraction cords to prevent spontaneous bone regeneration.

a

b

c

Fig 3 Er:YAG laser treatment and augmentation procedures in groups A (a and b) andB (c and d). (a and c) Two months after the implant surgery and peri-implantitis phase,
Er:YAG laser was used to decontaminate the implant surface. (b and d) A mixture of 50%
autogenous bone and 50% xenograft was used to fill the osseous defects, and the composite was covered with a collagen barrier membrane.

dPeri-implantitis treatment

Two months after the implant surgery and the induction of periimplantitis phase, Er:YAG laser(surface ablation set to 100 mJ/mm2,
20 pps) treatment was rendered forboth groups A and B. Twenty implants from groups A and B received
Er:YAG laser treatment in addition tobone grafting/membrane treatment(Fig 3), while the remaining four implants from group C received only
the bone grafting procedure without
Er:YAG laser treatment. Flap accessallowed for Er:YAG laser treatmentof the implant surface. The micro­
explosions from the laser removed
the contaminated oxide layer fromthe implant surface, a mixture of

autogenous bone and 50% xenograft (Equimatrix, Osteohealth) wasused to fill the osseous defects, andthe composite was covered with acollagen barrier membrane (Collagen Membrane, Dentium) to help
contain the bone graft material.13
Wound closure and postsurgical animal care protocols were exactly thesame as for previous procedures.

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464

Fig 4a Very good BIC,
including reosseointegrationof previously contaminatedimplant threads, can be notedon this group A specimen.

Fig 4b Another group A
specimen demonstrating partial
reosseointegration of previously contaminated implant
threads.

Light microscopy

All six animals were sacrificed 3months after peri-implantitis treatment, and the jaws were resecteden bloc using an oscillating autopsy saw. The recovered specimens
were immediately immersed in fixative for histologic preparation andevaluation.
Following complete dehydration, the specimens were embedded in ascending grades of ethanol(60%, 80%, 96%, and absolute ethanol) in a light-curing one-component
composite resin (Technovit 7200
VLC, Heraeus Kulzer). Polymerizedblocks were initially ground to bring
the tissue components closer tothe cutting surface. A 100-µm-thicksection attached to the second slide
was sawed with a diamond blade
and 50 to 100 g of pressure. The
block sections were sectioned again
in a mesiodistal direction, parallel tothe long axis of the implant. The final thickness of 40 µm was achieved

Fig 4c Group B specimen
demonstrating good BIC, but
complete reosseointegration ofpreviously exposed threads has
not been achieved.

by grinding and final polishing with
1,200-, 2,400-, and 4,000-grit sandpaper. Sections from each block
were used for Sanderson RBS staining and acid fuchsin counterstain.
Light microscopic overview imagesof the cores were taken digitallywith a Leica M16 stereomicroscope(Leica Microsystems).

Fig 4d Another group B
specimen demonstrating good
BIC, although several threads
were still exposed.

in place at the conclusion of thestudy with minimal gingival inflammation. Many of the cover screws
were visible, and some had recession of two to three threads. There
were no clinical distinguishing features between the two groups.

Histology

Results
ClinicalThis investigation was designed toemulate clinical situations, including localized edentulous ridges(delayed implant placement) and
implant placement into extraction sites. Both groups presented
significant bone defects that wereallowed to develop into chronic
inflammatory defects through theplacement of dental floss in thespace between the implants andbone for 6 weeks. All implants were

Most of the histologic results demonstrated improved BIC to a varying but sufficient degree to enablea patient to continue using theimplant. The gingiva was almost
depleted of inflammatory cells,
indicating the resolution of infection. There was new bone in contact with the implant surface for
implants treated with the Er:YAG
laser (groups A and B; Figs 4a to4d), in contrast to the results of thegroup C implants (Fig 5), where
there was a façade of new bone andweak BIC. This may be obscuredin the radiographic analysis but is

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465
Fig 5 Group C specimen demonstrating weak BIC
and lack of reosseointegration of previously contaminated implant threads.

obvious when assaying the histologic results. Histomorphometricanalysis revealed 3.37 ± 0.72 mm
of new bone formation for group A,
2.56 ± 0.71 mm for group B, and1.83 ± 0.75 mm for group C.

Discussion
Peri-implantitis, a chronic inflammatory process resulting in a loss of
BIC on osseointegrated implants,
has surfaced as an international
dental clinical reality.1–3 This is nota condition that one should anticipate for all implants, but is a serious
consideration when it occurs. Thereis considerable evidence of a causeand-effect relationship between microbial plaque colonization and theperi-implant infections.4–7 This has
led to a series of protocols, surgical and nonsurgical, to resolve theproblem, but there is a paucity ofevidence to suggest any one treatment modality.8–12 An ideal therapy

should arrest the disease and promote the regeneration of substantial lost BIC.
The Er:YAG laser system seems
to be promising in this application
because it possesses the capacity
to effectively remove calculus andbacterial colonizations from the titanium implant with no thermal side
effects on adjacent tissues due tothe high absorption of its emission
wavelength (2,940 nm) by water.14,15
The Er:YAG laser has potential todemonstrate an important role intreating peri-implantitis due to themicroexplosions that are created
when the laser energy is absorbedby the water, and the volume can
expand by 800 to 1,000 times.16
The Er:YAG laser is effective at
eliminating both the accretions on
the implant surface and the contaminated oxidized titanium layer
without affecting the potential for
reosseointegration. The realistic result relates to the level of bone loss,
but the endpoint goal is a treatedimplant that will continue to function successfully for the patient.
This study was designed withthe understanding that a more aggressive reconstructive protocol
with a stable structured scaffold
would be necessary to gain complete regeneration of the extensive
defects created in this preclinicalstudy. It has been previously demonstrated that vertical defects in preclinical models can be predictably
regenerated with a nonresorbablebarrier membrane (eg, expanded
polytetrafluoroethylene).16
The
present authors selected a regenerative approach to concentrate on
the potential positive effect of the
Er:YAG rather than the regenerativetechnique. The regenerative protocols used in this study have been
well documented in the treatmentof localized edentulous defects using bone augmentation for dental
implant placement.9–15,17,18 In order
to better understand the therapeutic effects of the laser, the present

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466
authors selected a combination of
50% autograft and 50% xenograft
together with a resorbable membrane, as these are a common treatment regimen utilized in clinicalpractice.19
The overall observations werea reflection of the defect size as aproportion of the threads denuded. Most of the results were similar
in regard to arresting progressionof disease and the establishmentof a strong BIC, but there is a notable difference in the percentageof new bone recovery. The results
suggest this would be a preferable
option compared with removal of
an implant and re-treatment in posterior areas, but its selection would
be subject to individual consideration when treating the esthetic
zone. The authors have studied theextent and quality of osseointegration on a previously diseased implant surface.13

Conclusions
The results of previous researchdemonstrate the capability of the
Er:YAG laser to decontaminate
the implant surface by removing
the contaminated oxide layer toprovide a fresh surface for regeneration.10 It has also been demonstrated that there is a minimal risein temperature and, therefore, novisible damage to adjoining bone.
The use of the Er:YAG laser for implant surface treatment allowed forregeneration and improved BIC inthis preclinical study. New BIC andarrest of the inflammatory process
in the soft tissues were observed.

Acknowledgments
The authors reported no conflicts of interest
related to this study.

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