Laser de-epithelialization for enhanced guided tissue regeneration. A paradigm shift?

The rationale for laser de-epithelialization stems from the attempts to block the down-growth of epithelium into the healing periodontal wound after surgery and prevent formation of a long junctional epithelial attachment. This concept has seen numerous techniques for accomplishing the blockage of epithelium. The advent of GTR was an offshoot of this concept and led Gottlow et al [table: see text] to examine the effects of selectively blocking certain cell types from contacting the root surface during periodontal wound healing. The use of a CO2 laser to de-epithelialize the gingival flaps is an attempt to exclude this cell type from the healing wound and has been used with and without the benefit of GTR membranes. In a study on beagle dogs, the histologic results of using membranes and the laser procedure enhanced the wound healing and regeneration of new bone, cementum, and connective tissue attachment when compared with paired defects using the membranes alone. The results from the human studies and case reports combined with the animal studies indicate a positive benefit in wound healing because of the laser de-epithelialization technique. The use of an osseous graft in treatment of periodontal defects has been shown to stimulate new bone growth effectively and to regenerate new attachment. It has been speculated that the additional benefit of an osseous graft in GTR procedures is the organization of the blood clot at initial healing, which may tend to maintain the space needed for regeneration and to provide a matrix for the fibrin clot to retard epithelial down-growth. Studies comparing the results of osseous grafting with flap debridement always have shown that the amount of new bone formation and clinical new attachment favor the grafted sites versus paired nongrafted sites. The effects of removal of the pocket epithelium at the time of periodontal surgery have been studied by several authors, and these studies generally shown an incomplete removal of the sulcular epithelium by the inverse bevel incision. Epithelial excision was studied by Centty et al, who compared the removal of sulcular epithelium by the CO2 laser technique with conventional methods. Their results confirm that (1) a more complete removal of sulcular epithelium was obtained by laser than by knives, and (2) the technique effectively removes the oral and sulcular epithelium from a gingival flap without damaging the viability of the flap during wound healing. The technique as described in this article was used by Israel et al to verify further the ability to maintain a viable gingival flap during multiple laser deepithelialization procedures in humans during the first 30 days of healing. [table: see text] The concept of laser de-epithelialization as an adjunct to regenerative periodontal procedures currently is being studied in a multicenter university setting using a parallel study in controlled clinical trials. The first of these reports was mentioned previously (Araujo et al, unpublished data) and shows the enhanced wound healing of periodontal defects through use of the laser de-epithelialization technique. The authors believe that this technique has shown significantly better results than those obtained through conventional osseous grafting alone and appears to be comparable to the results reported for GTR procedures with barrier membranes. This concept provides a paradigm shift from the conventional use of GTR therapy by acknowledging the difficulty in controlling epithelium during the early wound healing. It also allows a more comprehensive therapy for treating periodontal disease that addresses the generalized nature of the disease, with multiple lesions being treated concurrently in an economical manner. The patient presenting with generalized advanced periodontal disease could have several defects definitively treated in one quadrant using the laser deepithelialization technique without the need for multiple membrane therapy. (ABSTRACT TRUNCATE

A comparative evaluation of hemostatic agents in the management of soft tissue graft donor site bleeding.

BACKGROUND: Periodontal plastic surgery has increased the use of palatal wounds for donor tissue, with the most common complication being excessive bleeding from the palate after harvesting tissue. This study was conducted to evaluate the efficacy of 3 methods for achieving hemostasis on the palate after harvesting donor tissue for autogenous soft tissue grafts. METHODS: Thirty sites were evaluated at surgery for hemostasis and followed over 21 days for healing and adverse events. Three treatment groups were randomly selected and patients received either a test product or control comprising: 1) oxidized regenerated cellulose; 2) absorbable gelatin sponge; or 3) sterile gauze with external pressure as the control. All patients received a surgical stent for the palate. RESULTS: The results were analyzed for smokers and non-smokers, and the median time to hemostasis was significantly shorter when a hemostatic agent was applied to the palatal wounds compared to controls in both groups. Pain assessment showed no differences across treatment groups. However, by 21 days, only the oxidized regenerated cellulose group had complete healing based on blinded clinical evaluation with all sites rated as normal to rapid healing, compared to the absorbable gelatin sponge group where 40% of the sites were rated as slow healing. Adverse events, primarily bleeding episodes during the first 7 days after surgery, were found in 40% of the oxidized regenerated cellulose and gauze control groups, while no sites in the absorbable gelatin sponge group had an adverse event. The patients were followed for an average of 10 months and demonstrated a mean shrinkage of their recipient grafts of 24% in total surface area. CONCLUSIONS: This study concluded that the use of hemostatic agents for palatal wounds is confirmed as the treatment of choice when performing free soft tissue grafts.

New clinical index for drug-induced gingival overgrowth.

The numbers of patients using medications that induce gingival overgrowth are expanding rapidly. The tremendous increase in the number of organ transplants being performed, each requiring treatment with the immunosuppressive drug of choice, cyclosporine, has created a new dilemma in management of the gingival tissues. Additionally, cyclosporine-induced hypertension is frequently treated with calcium channel blockers, such as nifedipine, both drugs acting synergistically to induce gingival overgrowth. At present, the profession lacks a well-defined and easy-to-use clinical index for classifying overgrown gingival tissue. This article describes a comprehensive, yet simple, scoring system for enlarged tissues that may provide direction to the clinician and standardize evaluation. This system may also give guidance for the most appropriate time for surgical treatment of drug-induced gingival overgrowth.

An epithelial exclusion technique using the CO2 laser for the treatment of periodontal defects.

When treating osseous defects associated with periodontitis, the healed result is a compromised regeneration of the attachment apparatus from epithelial downgrowth. This article demonstrates a laser ablation technique for excluding the epithelium from contacting the root surface of the periodontal wound. In accordance with the principles of guided tissue regeneration, the epithelium should be excluded for at least 30 days after surgical therapy. A series of case reports demonstrate the technique and the 6-month results that can be obtained using this approach. The regenerated tissue is confirmed through reentry procedures and radiographs.

The effects of CO2, Nd:YAG and Er:YAG lasers with and without surface coolant on tooth root surfaces. An in vitro study.

The objective of this study was to compare and contrast the morphologic changes in tooth root surfaces treated in vitro by scaling and root planing followed by irradiation with the Er:YAG laser using air/water surface cooling and the CO2 and Nd:YAG lasers, both with and without surface coolant. The experimental unit consisted of 42 freshly extracted teeth which were divided equally and randomly assigned to the following 7 treatment groups: untreated control, S/RP only, CO2 laser with and without air/water surface cooling, Nd:YAG laser with and without/air water surface cooling, and Er:YAG laser with air/water surface coolant. Specimens treated with CO2 laser irradiation were subjected to energy densities ranging from 100 to 400 J/cm2; those treated with the Nd:YAG from 286 to 1857 J/cm2; and the Er:YAG was used within a range of 20 to 120 J/cm2. The degree of morphologic change following CO2 and Nd:YAG irradiation appeared directly related to energy density but unrelated to the use of surface coolant. Laser induced surface changes included cavitation, globules of melted and resolidified mineral, surface crazing, and production of a superficial char layer. In contrast, the Er:YAG laser produced root surface changes that might be expected from acid etching, i.e., removal of the smear layer and exposure of the collagen matrix. In addition, sharply defined microfractures of the mineralized structure were noted and unlike the CO2 and Nd:YAG lasers, there was no evidence of melting or surface char. Given the parameters of this study, it appears that both the CO2 and Nd:YAG lasers alter the root surface in an undesirable manner. The Er:YAG laser, however, when used at low energy densities shows sufficient potential for root surface modification to warrant further investigation.

Use of the carbon dioxide laser in retarding epithelial migration: a pilot histological human study utilizing case reports.

Predictable regeneration of tooth-supporting tissues lost to periodontal disease is the aim of periodontal therapy. Often the result of conventional treatment is healing with a long junctional epithelium along the root surface and little regeneration of the complete attachment apparatus. The purpose of this pilot study was to evaluate whether de-epithelialization with a CO2 laser at the time of flap surgery and at 10-day intervals over the first 30 days of healing has the potential to enhance the formation of a connective tissue attachment. Six mandibular incisors in two patients were selected for the study. Each patient received oral hygiene instruction and initial therapy prior to surgery. The teeth were splinted together, open flap debridement was performed on all teeth, a notch was placed on the roots at the height of the crest of the alveolar bone, and the flaps were sutured in place. The test side received controlled de-epithelialization of the outer (oral) gingiva with the carbon dioxide laser, and the inner gingival flap. The de-epithelialization was repeated on the test side at 10, 20, and 30 days postsurgically. Controls received open debridement only. Block sections were taken at 90 days and processed for histologic analysis. The results showed that for both patients, junctional epithelium (JE) was formed on both test and control teeth. In all control teeth, the JE extended the entire length of the root to the base of the reference notch.(ABSTRACT TRUNCATED AT 250 WORDS)

Multimodal treatment of drug-induced gingival hyperplasia in a kidney transplant patient.

Medical advances for treating organ diseases have resulted in thousands of organ transplants being performed each year. Every patient receiving a transplanted organ will also be placed on drugs that may induce gingival hyperplasia as a side effect. This article discusses the multiphasic approach to treating the disfiguring hyperplasia through chemical and mechanical plaque control, surgical removal of the tissue by lasers, and postsurgical rinses with folate.

Prevalence of periodontal disease in an active duty military population as indicated by an experimental periodontal index.

An experimental periodontal screening examination and index was used to measure the prevalence of gingivitis and periodontitis among 1,334 soldiers at Fort Knox, Kentucky. Although 12.1% of the subjects demonstrated no disease, 40.3% were found to have gingivitis. In this sample group, the occurrence of gingivitis decreased with increasing age. Early periodontitis (probing depths of 3-5 mm) was detected in 35.7% of the subjects, and subjects with moderate to advanced periodontitis (probing depths greater than 5 mm) comprised 11.9% of the sample. The screening exam used is suggested for use as part of each soldier's annual dental examination.

In vitro attachment of human gingival fibroblasts to endosseous implant materials.

In recent years, the focus of dental implant research has been the nature of the bone-implant interface associated with osseointegration, yet the transgingival portion of endosseous dental implants has received little attention. The purpose of this study was to determine the attachment of human gingival fibroblasts to three different implant materials: commercially pure titanium, non-porous hydroxyapatite, and porous hydroxyapatite. Cell attachment was quantified by radiolabeling gingival fibroblasts with tritiated thymidine and counting attached cells by liquid scintillation following incubation for periods of 20, 40, and 60 minutes. Additional studies coating implant surfaces with fibronectin were also performed. The nature of the implant material itself appeared to affect the number of attached cells. Determined on a surface area basis, fibroblast attachment was greatest to titanium followed by non-porous hydroxyapatite. Porous hydroxyapatite demonstrated the least amount of fibroblast attachment. When incubated with fibronectin at a concentration of 50 micrograms/ml, no increase in the number of cells attached to the various implant materials was observed. A small but statistically significant increase in the number of fibroblasts attached to porous hydroxyapatite at 40 minutes was observed when implant materials were pre-treated with fibronectin.

Retardation of epithelial migration in monkeys using a carbon dioxide laser: an animal study.

Obtaining a connective tissue attachment to the root surface following a mucoperiosteal flap surgery has been a goal of periodontal therapy for a long time. The objective of this study was to examine whether controlled de-epithelialization with the CO2 laser would retard the apical migration of the epithelium and thereby increase the amount of connective tissue attachment. Elastics were placed on the maxillary premolars and incisors of 7 cynomolgus monkeys to create periodontal defects. Open flap debridement was performed on each side. On the experimental side, the oral epithelium was removed by CO2 laser irradiation. This report describes the 3 specimens at 7, 14, and 28 days respectively. On the control side sulcular epithelium was seen at 14 days. Sulcular epithelium was first seen on the test side at 28 days. For all specimens over 7 days, there was a trend to less epithelium and more connective tissue attachment on the experimental side than on the control side. However, no statistical analysis was possible on this histologic study. The CO2 laser may be a useful tool to retard epithelium and thereby enhance new connective tissue attachment.

Benzodiazepine reversal with flumazenil--a review of the literature.

Benzodiazepines such as Valium (diazepam) or Versed (midazolam), as used in dental procedures for intravenous sedation, have been a boon to the profession. Yet in the event of sedation problems, no agent exists that consistently reverses all clinical effects of these drugs. This problem does not exist with narcotics, frequently employed in tandem with benzodiazepines, since an effective reversal agent, Narcan (naloxone hydrochloride), exists. It would be advantageous to effectively reverse benzodiazepines in cases of acute emergency with respiratory depression or paradoxical reactions, and to allow quick, full recovery after short dental procedures. None of the drugs currently available for benzodiazepine reversal, such as physostigmine, give consistent clinical results. The purpose of this paper is to discuss Flumazenil, a new specific benzodiazepine receptor antagonist, and its possible use for dental sedation procedures.

Cotinine in saliva and gingival crevicular fluid of smokers with periodontal disease.

A study was undertaken to determine the presence of cotinine, a metabolite of nicotine, in the saliva and gingival crevicular fluid of smokers with periodontal disease. Saliva and crevicular fluid samples were obtained from 16 habitual cigarette smokers and analyzed by High Performance Liquid Chromatography (HPLC) for the presence of cotinine. Thirteen non-smokers with periodontal disease served as controls. There was no evidence of cotinine (within our detection levels) in either the saliva or crevicular fluid of any of the nonsmokers. Cotinine, in a wide range of concentrations, was detected in the saliva and crevicular fluid in all of the 16 cigarette smokers. The presence of a nicotine metabolite in the saliva and gingival crevicular fluid reflects the extent of the systemic distribution of nicotine in smokers. The vasoactive properties of nicotine are well known and may possibly affect the pathogenesis of periodontal disease.

A comparison of mandibular lingual surgical flaps with and without a vertical releasing incision.

The purpose of this study was to evaluate the short-term postoperative pain for surgical flaps with mandibular lingual vertical releasing incisions (ML-VRI) compared with envelope flaps and to observe the postoperative clinical healing of ML-VRI. Using a split mouth design, 12 adult periodontal patients received bilateral posterior mandibular surgery with an envelope flap on one side and a flap with an ML-VRI on the contralateral side. Surgical procedures were performed at separate appointments, varied in order, and performed an equal number of times on the right and left sides. Postoperative pain was scored by the patients, and scores for each technique were compared using an analysis of variance and covariance with repeated measures. Photographs were used to assess postoperative clinical healing of ML-VRI with various degrees of initial closure. Results indicated no significant statistical difference (P greater than 0.05) between pain levels for the two surgical techniques. There was complete clinical healing despite variations in the degree of closure of ML-VRI. The findings of this study support the use of ML-VRI. They are indicated in areas with flat contours or with slight ledges and inferior concavities. ML-VRI are contraindicated in areas with prominent ledges and inferior concavities and in areas with exostoses. Suturing the vertical incision is unnecessary and may be detrimental to the tissues. A "step down" incision that preserves attachment levels in nondiseased sites is discussed.

Effects of CO2 laser irradiation on gingiva.

A CO2 laser (Coherent Medical Model 400) was used to irradiate the gingival tissue of a cynomolgous monkey to determine laser effects on the epithelium and underlying connective tissue. A focal length of 400 mm and a 10-watt power setting at 0.2- and 0.5-second exposure was used. Biopsy results indicated that a 0.2-second duration of CO2 laser irradiation was inadequate to completely de-epithelialize the gingival tissue. A 0.5-second exposure exhibited complete epithelial destruction with little or no disturbance of the underlying connective tissue layer and viable connective tissue 1.0 mm below the impact site.