Histologic Evaluation of an Nd: YAG Laser- Assisted New Attachment Procedure in Humans
Raymond A. Yukna. DMD, MS*
Ronald L Carr, DDS** Gerald
H Evans. DDS”
This report presents histologic results in humans following a taser-assistec/new attachment procedure (LANAP®) for the treatment of periodontal pockets. Six pairs of single-rooted teeth with moderate to advanced chronic periodontitis associated w/th sub gingiva/ calculus deposits were treated. A bur notch was placed within the pocket at the clinically and radiographically measured apical extent of calculus. All teeth were scaled and root planed with ultrasonic and hand scalers. One of each pair of teeth received treatment of the inner pocket wall w/tha free-running pulsed neodymium:yttrium-aluminum-gamet (Nd:YAG) laser to remove the pocket epithelium, ano* the test pockets were laseda second time to seal the pocket. After 3 months, all treated teeth were removed en bloc for histologic processing. LANAP®-treated teeth exhibited greater probing depth reductions andclinical probing attachment level gains than the control teeth. All LANAP®-treated specimens showed new cementum and new connective tissue attachment in and occasionally coronal to the notch, whereas five of the six control teeth had a long junctional epithelium with no evidence of new attachment or regeneration. There was no evidence of any adverse histologic changes around the LANAP® specimens. These cases support the concept that LANAP® can be associated w/th cementum-mediated new connective tissue attachment and apparent periodontal regeneration of diseased root surf aces in humans. (Int J Periodontics Restorative Dent 2007;27:577-587.)
Regeneration of the supporting tissues of the teeth is a primary goal of periodontal therapy. Whereas clinical results and animal histology suggest that n ew connective ti ssue atta ch m ent (CTA) as well as regeneration of cementum (CEM), periodontal ligament (PDL), and alveolar bone (AB) can occur on human teeth affected by periodontitis as a result of several treatment approaches, histologic evidence in humans of successful cases and successful treatments is limited.1
The 1996 World Workshop in Periodontics established specific histologic c liter ia for proof of reg en erat ion. Experimental teeth must have loss of CTA and AB associated with periodontitis. In addition, subgingival and/or subcrestal calculus must be present at the time of surgery so that a notch ca n be ma de i nto th e root at th e apical extent of calculus. Proof of new attachment is demonstrated by new CEM and CTA, and regeneration is evidenced by the presence of new CEM, PDL, and AB coronal to the apical extent of the notch. Most treatments that show proof of new attachment and regeneration are associated with surgically implanted devices or materials.1’21
‘Professor, Department of Periodontics, Louisiana State University School of Dentistry, New Orleans, Louisiana.
“FVofessor, Department of Oral Pathology, Louisiana State University School of Dentistry, New Orleans, Louisiana.
Correspondence to: Dr Raymond A. Yukna, Advanced Periodontal Therapies, University of Colorado Dental School, 13065 East 17th Place, Room 111, P.O. Box 6508, MS F847, Aurora, CO 8004S; fax; 303-724-0162; e-mail: [email protected]
Sulcular/pocket epithelium removal has been the basis or foundation of subgingival curettage (CUR), the excisional new attachment procedure (ENAP), and the replaced flap/modified Widman fla p procedu re to set up an environment for new CTA.22-25 However, elimination of pocket epithelium by CUR, ENAP, or other internal- bevel incision designs appears nearly impossible.26
Procedures limited to treating the soft tissue wa II of periodonta I pockets such as CUR and ENAP would not be expected to influence new bone formation to a ny great degree but hope-fully would lead to healing with a CTA ratherthan a long junctional epithelium (UE). Almost all available human histologic evidence to date demonstrates healing by an UE with no or minimal CTA27
Interest in neodymiurrvyttrium:aluminum-garnet (Nd:YAG) laser use in periodontics is increasing. Several papers have suggested favorable results with its use in the treatment of periodontal pockets.28-30 A procedure called laser ENAP has been promoted in trade journals with examples of radiographic bone regeneration.31’32 Referred to as the laser-assisted new attachment procedure (LANAP®) inthis report, this technique of pocket therapy has recently been approved by the US Food and Drug Administration (FDA 51 Ok clearance K030290).
In clinical case reports LANAP® has demonstrated improved clinical measurements a nd some radiographic evidence of bone regeneration in the areas treated.33-37 However, it is not known what tissues constitute the new healed interface between the soft tissues and the tooth root. Also, there is some evidence that the use of lasers in periodontal pockets may damage root surfaces,38-10 adversely affect the adjacent alveolar bone,50,51 or cause undesirable pulpal changes.48,49 Clinical case reports have reported favorable results, but there is no human histologic proof of the nature of the healing following LANAR The purpose of this paper is to report histologic wound healing following use of LANAP® surgery for periodontal pockets.
Method and materials
Dental radiographs of patients assigned to the Postgraduate Periodontics Clinic, Louisiana State University (LSU), were screened for the presence of teeth that had isolated moderate to severe periodontal involvement (probing depths and clinical probing attachment loss of 5 to 9 mm with bleeding on probing and evident subgingival calculus). Teeth that had been treatment planned by dinicians in the Oral Diagnosis and/or Prosthodontics departments for extraction as part of the overall restorative treatment plan were induded in the study. Subjects had to provide two single rooted teeth with similar periodontal involvement forthe study and signed an LSU-approved consent form prior to beginning the study.
Preoperatively, the subjects received occlusal adjustment/odontoplasty to reduce ooolusal forces on the experimental teeth, and study teeth were splinted to neighboring teeth with an extracoronal bonded splint (Ribbond, Ribbond Inc). Scaling and root planing were performed on othe r teeth in the same segment (not the treatment teeth), and general supragingival prophylaxis was provided forthe rest of the mouth.
Documentation consisted of dinical photographs, radiographs with stent and grid (Fig 1), modified Gingival Index (mGI),52 Quigley-Hein Plaque Index (PI),53 and clinical mobility evaluation.54 Clinical measurements were made from the cementoenamel junction (CEJ) to the free gingival margin, from the CEJ to the base of the pocket, from the CEJ to the apical extent of clinically and radiographically evident calculus, and from the CEJ to the mucogingival junction. Bleeding on probing (BOP) was also assessed.
Appropriate laser safety precautions were used. Under regional local anesthesia, a quarter round bur notch was placed at the clinically and radiographically measured apical extent of calculus as carefully as possible. One of each pair of teeth randomly received Nd:YAG laser treatment (Periolase, Millennium Dental Technotogies) of the i nner pocket wa II to remove the crevicular epithelium around the necks of the study teeth, relax the gingival collar, and expose more of the contaminated root surface. The fibertipof the laser was directed parallel to the root surface and was moved laterally and apicalry along the pocket wall, eventually reaching dose to the base of the pocket. The laser settings for this first pass were 3 W, 150-us pulse duration, and 20 Hz. Once the epithelial lining was removed, root debridement was accomplished coronal to the area of the calculus reference notch with ultrasonic (EMS Piezon 4C0, EMS) and hand instrumentation.
Fig 1 Radiographs of a 54-year-old man with deep infratony defeca on the mesial of torn maxillary canines.
Fig 1a(left} Mesial defecton the right canine (left), treated iw’th LANAR demonstrates a radiographic increase in tone den¬sity and apparent fiil of defect at 3 months after treatment (right).
Fig lb Mesialdefectonrhe left canine (left), treated iMth scaling and root planing without laser demonstrates little change in the tony defect contour or Done density after3 months.
No attempt was made to remove any soft/granulation tissue with the mechanical instrumentation. The pocket contents of the test teeth were lased again (4 W, 635-us pulse duration, and 20 Hz) to help achieve a solid fibrin clot and form a pocket seal. The control teeth received all of the aforementioned treatment except for the lasertherapy No sutures were used, and triple antibiotic ointment and a light-cured dressing (Barrica id, Dentsply/Caulk) were placed cnall teeth. Al I patients were provided with nonsteroidal anti-inflammatory medications, doxycycline (100 mg daily for 10 days), and 0.12% chlorhexidine rinses (to be used twice daily).55
After3 months, a second surgical procedure was performed to remove the experimental tooth roots en bloc according to methods described pre-viously4-9-56-57 For all teeth this was a single proximal area. The body of each tooth root was bisected longitudinally in a faciolingual plane, with the clinician attemptingto keep at least half ofthe root diameter attached to the area of interest. A small interproximal wedge oftissue and a section of root approximately 5 mm wide, 7 mm long, and 5 mm thick was removed.
Once the desired specimens were completely freed, they were gently and atraumatically removed, rinsed gently in sterile saline, and placed in 10% neutral buffered formalin. The residua I defects were reconstructed, and after an appropriate healing period, the patients were referred for prosthetic replacements.
Essed by the LSU School of Dentistry Research Histology Laboratory, where they were decaldfied, embedded in paraffin so as to obtain longitudinal mesiodistal serial step sections, serially sectioned at 7 urn in the area of the notch, and stained with hematoxylin and eosin. The three most central 200-um serial step secticns were blindly and randomly evaluated for the nature ofthe healed tissues—specifically the presence and length of new CEM, new CTA, new AB, and healed junctional epithelium relative to the apical extent of the calculus notch. Histomorpho-metric measurements were made by an oral pathologist (RLQ using an eyepiece grid on the microsoope. Root resorption, ankylosis, pulpal changes (where pul p tissue was visible), and the degree of inflammation were also evaluated. Mean values for the three sections of each tooth were used for linear measurements.
LANAP® = jlaser-assisted new attachment procedures; SCL/RP = scaling and root planing;
CAL = clinical attachment level.
*Coronal to cementoenamel junction.
Fig 2 Histologic views of LANAP®-treated maxillary right canine from Fig 1a (hematoxylin & eosin). fleftJ Low-power view (Xl) with box around area of interest, (center,! Medium-power view (X 16) showing calculus notch (N) with new cementum (C) in and coronal to the notch and old cementum (OC) apical to trie notch, apical extent of junctional epithelium (JE), and newbone (B) adjacent to tfie notch, (right,) High-power view (X 40) of notch area demonstrating new cementum (C) filling tfie notch (N) and extending coronally, old cementum apical to the notch (OC) covered by new cementum, new alveolar bone (B), and new periodontal ligament and gingival fibers attached to the tooth.
Clinical results are presented in Table 1. mGI, PI, and BOP were improved on all testand control teeth. Total energy applied to the test pockets ranged from 14 to 25 J/mm of probing depth (mean 19 J/mm).
All six LANAP®-treated specimens showed new CEM and new CTA in and occasionally coronal to the notch (Figs 2 to 5). In two specimens, the notch was within the infrabony pocket (sub-crestal) and the new CEM and new
Fig 3 LANAP®-treated mandibular left second premolar of a 48-year-old man vwth an infrabonydefect (hematoxylin & eosin). fleftJ Low-power view (X1) outlining the area of inter¬est, (center and righlj Medium-power (X16) and high-power (X 63) views showing the calcu¬lus notch (N), th/’n layer of new cementum (C) in and coronal to the base ofthe notch, junc¬tional epithelium (JE) at the coronal level, newCTA with Sharpey fibers (SF), and newbone (B) adjacent to the notch. (Cementum is artificially separated from tooth.)
Fig 4 LANAP®-treated premolar w/th calculus notch coronal to bone crest (hematoxylin & eosin). (\eh) Low-power overview (X1) with box around area of interest, (center and right,) Medium-power (X 10) and high-power (X25) views with new cementum (C) in and coronal to the base of the calculus notch (N). The apical extent of the junctional ep/’the/jum (JE) stops near the coronal limitof new cementum. B = alveolar bone.
Fig 5 Canine tooth with calculus notch corona/ to bone crest treated with LANAP® (hematoxylin Steosin). (left) Low-power (X1 ) view with box around area of interest, (right) Medium-power fx 10) Mew showing new cementum (Q in and coronal to the calculus notch (N). New CTA is evident between new cementum and trie apical extent of the junctional epithelium (JE).
*Mean amount, in millimeters, from micrometer readings.
LANAP® = laser-assisted new attachment procedure, SCL/RP= scaling and root planing; CTA = connective tissue attachment.
CTA were adjacent to new AB, technically showing periodontal regeneration. Rve of the six control teeth had an UE, with no evidence of new attachment or regeneration (Figs 6 and 7). One control specimen did show a small amount (0.1 mm) of new CEM and CTA. There was no evidence of any adverse histologic changes to the root surface or the pulp of any of the teeth. Histologic results are presented in Table 2.
Fig 6 Control tooth treated with scaling and root planing without laser application (hematoxylin &eosin). (left) Low-power (x 1) view with box around area of interest, (right) Medium-power (X10) image showing calculus notch (N) with no evidence of new CEM, new AS, ornewCTA The junctional” epithe-lium (JE) extends to the apical extent of the notch.
Fig 7 Manc/ibu/arpremo/ar that received control treatment (scaling and rootplaning alone) (hematoxylin & eosin). (left) Low-power fx 1) view with box around area of interest, (right) Medium-power fx 10) view demonstrating lack of good tissue contact with root even though CTA is present between the calculus notch (N) and junctional epithelium (JE). No new CEM is evident, and some epithelial islands ftp) are present at the depth of the pocket and as islands within the connective tissue.
This human histologic report demonstrates favorable histologic healing with the useof the free-running pulsed Nd:YAG laser used in a specific patented technique of LANAP® Apparent periodontal regeneration (CEM, PDL, AB) on a calculus- and plaquecontaminated area of the root was seen on two of the test teeth, and CEM-mediated new attachment was evident on the other four laser-treated teeth. Similar periodontal healing in humans has been shown with other surgical techniques.2-21 , 58-60
The histologic assessment was based primarily cn preserxe/absence criteria but also induded linear measurements of new CEM length. As with the control teeth in thts report, the literature demonstrates consistent and almost un iversal hea ling by U E following scaling and root planing, gingival curettage, and open flap debridement procedures2,3,56-57,59-62 and variable histologic results with bone replacement graft materials and miscellaneous regenerative agents on contaminated rootsurfaces.3-21,59,60,61,63-68
Comparison of the results of this study with those from a study that used demineralized freeze-dried bone allografts2 suggests essentially equivalent histologic results using the LANAP® procedure. In this study new CEM was seen in 100% of the cases versus 77% of the cases in the Bowers et al 2 study; new CEM length was the same (1.2 mm) as in Bowers et al; and the frequency of new CTA was 100% versus 68% for Bowers et al. It should be noted that the number of specimens was larger in the study of Bo we rs et a I.
Treatment allocation could not be concealed from the therapist, as he had to use the laser on one tooth and not the other. Treatment (laser or no laser) was allocated according to a random code after all preliminary measurements and procedures, including placement of the calculus notch, had been completed.
Accurate placement and evaluation of the calculus notch presented severa I chal lenges Since no fla ps were reflected, direct visualization of thecalculus was not possible. Positioning of the notch was based on repeated measurements from the CEJ to the clinically detectable calculus and evaluation of calculus when it was evident on the radiographs. The appropriate “depth” was marked on the shank of the quarter round bur, and the notch was placed as carefully as possible. Again, because no flap was reflected, the depth of the notch into the root was confined to the lateral part of the bur head and was necessarily limited. It is true that there is no direct way to guarantee that the notch was actually placed in calculus, but this was the most tedious and difficult part of the entire procedure because the depth of the bur placement and therefore the depth of the notch was based on clinical and/or radiographic detection of calculus. Since clinical and radiog raphic detection of ca leu lus leads to many false-negative but nofalse-positive results, it is felt that this was as accurate as could be accomplished with the dosed procedure employed. In addition, if any error was made it was to plaoe the notch more coronally to be sure that it was in calculus and/or contaminated root surface. On the histologic slides, the position of the notch was verified by using the clinical measurements related to the CEJ or biopsy-related landmarks.
It should be emphasized that the LANAP® is a combined therapy using a patented protocol (US patent #5,642,997) that includes several aspects: occlusal adjustment, splinting when needed, systemic and topical antibiotics, laser use for surgical pocket epithelium removal, scaling and root debridement, and laser use for tissue stabilization (welding) against the tooth surface withafibrin clot. Use of the laser without attention to these other aspects may not yield the results reported here. It should be recognized that LANAP® is a single-treatment surgical procedure. Since tissue is surgically removed from the lining of the pocket with the laser (rather than with a seal pel) and occlusal adjustment is an integral part of the protocol, it would appear that only qualified clinicians can legally perform the treatments in most locales.
In condusicn, this study demonstrated consistently positive histologic responses in periodontal pockets in humans treated with the LANAPCEM mediated new attachment and occasionally apparent periodontal regeneration following a specific protocol with a free running pulsed Nd:YAG laserwere demonstrated.
This study was supported by Millennium Dental Technologies. which provided the laser, trainning and funding. The evaluations and conclusions made are solely those of the authors. The authors wish to acknowledge the histologic processing provided by Joanne Canale: the clinical assistance of Elizabeth Mayer. ROH. Stephanie Well. CDA. RDH. and Susan Bllllot. RDH; ard the efforts of Julie Behan. RHI A. and Aubrey quinn in preparing Ihis manuscript.
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