A clinical study of root surface conditioning with an EDTA gel. I. Nonsurgical periodontal treatment.

The present study was undertaken to investigate if subgingival administration of an EDTA gel has any adjunctive effect to subgingival and supragingival root debridement. The investigation was performed in one study center involving 6 clinical investigators and 91 patients. The patients were selected from 2 patient populations: 41 were included from a consecutive referral material on a voluntary basis, and 50 were included from a maintenance care material at the clinic. No significant differences were found between the EDTA-treated and control groups with respect to clinical attachment gain or probing pocket depth reduction. The referral patients showed a significant improvement of pocket depth and attachment gain compared to maintenance care patients at the clinic. In multiple regression analyses, it was found that patients with small attachment losses at baseline responded better to treatment than patients with severe periodontitis. Also, in multivariate analyses, referral patients responded better than maintenance patients when controlling for other predictors.

A clinical study of root surface conditioning with an EDTA gel. II. Surgical periodontal treatment.

The objective of the present trial was to assess the effect of an EDTA gel applied during surgical periodontal therapy on probing depth reduction and periodontal attachment gain, allowing for the influence on healing of smoking as well as postsurgical oral hygiene. For comparison, citric acid treatment and control surgery only were included. The investigation was performed in one study center involving one clinical investigator and 68 patients. The patients were selected from a consecutive referral material on a voluntary basis. No statistically significant differences between treatment groups concerning attachment gain or pocket depth reduction could be seen after 3 and 6 months. A subgroup of the sample--21 patients who scored zero on the bleeding index at 3 and 6 months postsurgery and did not smoke--had a borderline significantly higher attachment gain in response to experimental treatment as well as a significant pocket depth reduction 6 months postsurgery when controlling for age, gender, Plaque Index at baseline, and treatment in multiple regression analyses. However, this was true not only for EDTA treatment but for citric acid and control treatment as well.

A new concept for etching in restorative dentistry?

The purpose of the present study was to investigate the scanning electron microscopic texture of enamel and dentin cavity surfaces in extracted human teeth following different etching modalities, specifically combinations of etchants adapted to the tissue composition of the cavity walls. It was concluded that an etching technique that combined the action of 2 different etchants--ethylenediaminetetraacetic acid (EDTA) on dentin and phosphoric acid on enamel--optimized retention structures on each tissue surface of a dental cavity better than either 1 of the 2 etchants that were applied to both types of tissue in the cavity walls.

Skin-prick test for severe marginal periodontitis.

The present study tested the hypothesis that treatment-resistant periodontitis patients present with a more intense inflammatory response to marginal bacterial plaque as a sign of an inflammatory overreaction. Patients with severe marginal periodontitis (Gingival Index > 20%) who had not responded to treatment showed almost no positive response to lipid A in a skin-prick test, which was significantly different from the results from patients with severe marginal periodontitis who had responded to treatment and from healthy control individuals without marginal periodontitis. This finding can be interpreted as an impaired inflammatory reactivity to periodontitis pathogens in treatment-resistant patients, rejecting the hypothesis.

Chlorhexidine as a root canal medicament for treating inflammatory lesions in the periodontal space.

The purpose of the present study was to investigate the therapeutic effect of intra-canal application of chlorhexidine on inflammatory root resorption. Dental pulps from monkey incisors were infected and resealed prior to extraction of the teeth. Root dentin was mechanically exposed and the teeth were replanted under aseptic conditions. After 4 weeks, the experimental teeth were dressed with chlorhexidine gel and resealed. Animals were sacrificed 4 weeks later, and their jaws prepared for histologic examination. Results showed that both marginal and apical periodontal inflammation and resorption were reduced in the chlorhexidine-treated teeth. It was concluded that the use of intra-canal chlorhexidine may be a useful adjunct in the treatment of inflammatory root resorption, but further human trials need to be undertaken before its clinical use can be recommended.

Cervical root resorption associated with guided tissue regeneration: a case report.

Root surface resorption, ankylosis (replacement resorption) and alveolar bone resorption are not uncommon sequelae to periodontal healing in both animal and human trials whether the treatment objective is regenerative, preventive, or conservative. The present report describes a case with progressive cervical root resorption in a patient who received periodontal regenerative treatment with guided tissue regeneration (GTR). A 46-year-old woman was referred for treatment of severe periodontitis. Remaining radiographic attachment was less than 50%. Following a period of 18 months, during which non-surgical and surgical therapies were performed, angular defects were diagnosed on radiographs and recurrent bleeding periodontal pockets (6 mm) were found in the proximal areas of 24 and 25. Root caries was not present. Periodontal surgery with GTR was performed in this area. No immediate postsurgical complications were noted. Two years later, clinical and radiographic examinations revealed gingival recession with bleeding periodontal pockets (6 mm) which had partly uncovered severe proximal cervical resorptions in 25. Root surface caries was not present. Following surgical inspection, the root of 25 was removed. The root was subsequently prepared for histological analysis. Resorption cavities covered almost the entire cervical proximal surface of the root above intact infracrestal cementum and were covered by numerous CD68+, both mononuclear and multinucleated cells. In a central area as indicated on the radiographs, the cavities penetrated into the root canal. There was no evidence of root caries.

Effect of different concentrations of EDTA on smear removal and collagen exposure in periodontitis-affected root surfaces.

The purpose of the present study was to explore the possibility of obtaining an acceptable smear-removing and collagen-exposing effect following EDTA etching with concentrations lower than supersaturation (24%). A flat dentin surface was created on human teeth extracted due to severe periodontitis. The teeth were etched with the following concentrations of EDTA for 2 min: 1.5% (group I), 5% (group II), 15% (group III) and 24% (group IV), and evaluated with scanning electron microscopy with respect to smear layer removal and exposure of root-associated collagen fibers. It was found that neither 1.5% nor 5% EDTA etching was sufficient to dissolve the smear layer to any higher degree. Etching with 15% EDTA dissolved the smear more effectively than the lower concentrations and collagen fibers were sparsely found. Following etching with 24% EDTA (group IV), significantly less smear was seen on the dentin surfaces than in any of the other groups and collagen fibers were seen covering the entire intertubular dentin surfaces. Based on these findings, the concentration of EDTA should be somewhere between 15 to 24% in order to obtain an acceptable smear removing and collagen-exposing effect within a clinically acceptable time period.

Smear layer formed by different root planing modalities and its removal by an ethylenediaminetetraacetic acid gel preparation.

The purpose of the present study was (1) to examine smear layer formation following different root planing modalities, and (2) to evaluate its removal and the exposure of collagen using an ethylenediaminetetraacetic acid gel preparation. Twenty-four periodontitis-affected human teeth were mechanically root planed. Twelve teeth were etched with an ethylenediaminetetraacetic acid gel preparation. The surfaces were examined by a scanning electron microscope. The results showed that root planing resulted in a smear layer covering the root surfaces, irrespective of treatment modality. The smear layer could be efficiently removed with the ethylenediaminetetraacetic acid gel preparation. During this process, collagen fibers were exposed to varying degrees.

Prognosis and mortality of root-resected molars.

The purpose of the present study was to compare tooth mortality of root-resected molars with that of root-filled, single-rooted teeth. Survival rates were 68% for root-resected molars and 77% for root-filled single-rooted teeth over a 10-year period. This difference was not statistically significant. Ten-year survival of root-resected molars in patients with radiographic attachment loss in single-rooted teeth of greater than 6 mm was 56% while survival was as high as 89% for root-resected molar patients with radiographic attachment loss in single-rooted teeth less than or equal to 6 mm. In conclusion, the prognosis of root-resection is not poorer than the prognosis of single-rooted teeth with an equal susceptibility to periodontitis, if endodontic conditions and maintenance care are optimal.

Periodontal healing in horizontal and vertical defects following surgical or non-surgical therapy.

The aim of the present study was to investigate any relationship between the level of oral hygiene and probing pocket depth reduction over time after periodontal treatment in sites with either vertical or horizontal destructions. The investigation was conducted as a retrospective study on a 3-year consecutive referral population of periodontitis-prone patients based on full-mouth oral radiographic examinations, probing pocket depth registrations and plaque scores. The analyses were performed on a final sample of 3064 sites in 107 patients with regression analysis after adjusting for dependence within the patient. Probing pocket depth was significantly less reduced over time in sites with vertical destructions compared to sites with horizontal destructions following non-surgical treatment. Furthermore, the difference in probing pocket depth reduction between vertical and horizontal defects following non-surgical treatment increased over time in sites with plaque compared to sites without plaque, thus reflecting the importance of the patient's plaque control, especially in sites with vertical destructions. However, the difference in probing pocket depth reduction between vertical and horizontal defects did not increase over time for surgically treated teeth, a finding which probably can be attributed to a more thorough debridement of vertical defects during surgery and/or osteoplasty/osteoectomy limiting the surface area upon which a long junctional epithelium can form, which may facilitate recurrence of a periodontal pocket.

Ultrasonic subgingival root planing and EDTA etching in a one-step procedure.

The purpose of the present study was to investigate if ultrasonic debridement and EDTA etching could be combined in a ore-step procedure. Tap water was exchanged for a 24% EDTA solution as irrigation agent during root planing with a piezo scaler. 24 human teeth extracted due to severe periodontal disease were used and the results were evaluated with scanning electron microscopy. Results indicate that synergistic effects (smear removal and exposure of collagen fibers) were negligible with conventional application of the irrigation fluid to the working area of the scaling tip while a marked effect was evident when the EDTA solution was applied directly to the working area of the piezoelectric scaler through a customized tip.

Smear removal and collagen exposure after non-surgical root planing followed by etching with an EDTA gel preparation.

Low pH aqueous solutions of citric acid have been used in surgical periodontal therapy mainly for two reasons. It dissolves smear after a relatively short exposure time and it has been claimed to selectively remove root surface-associated mineral exposing collagen to varying degrees. The use of low pH etching agents has recently been challenged in both experimental in vitro and in vivo studies based on their necrotizing effect on the surrounding periodontal tissues. The purpose of the present study was to assess the efficacy of subgingival application of an EDTA gel preparation in removing smear and exposing collagen fibers in root surfaces following non-surgical periodontal therapy. Root surfaces which were root planed did not reveal any patent dentinal tubuli or collagen fibers. This was in contrast to the findings seen after root planing followed by etching, where intertubular surfaces were covered by a dense fibrillar network extending into patent dentinal tubuli. In high magnification these intertubular fibers displayed the cross-striated texture typical for collagen fibers. Etching of root planed surfaces with EDTA may thus enhance the effect of non-surgical root debridement in the same way as has been shown during experimental surgical procedures.

Root surface etching at neutral pH promotes periodontal healing.

The purpose of the present investigation was to examine whether an etching agent operating at neutral pH (EDTA) can enhance healing compared to a low pH etching agent (citric acid) in an animal model. Maxillary molars and premolars, in total 32 teeth, in 4 monkeys were divided between test (EDTA or citric acid treatment) and matched control groups. Periodontal surgery on both palatal and buccal roots using the dehiscence model was performed with or without root surface etching. Healing results were evaluated histomorphometrically after 8 weeks. The statistically significant differences between EDTA treated surfaces (n=15) and control surfaces (n=11) were approximately 10% less failure (gingival recession and periodontal pocket), 10 to 15% more total histological attachment (long epithelial junction, connective tissue and reparative cementum), approximately 20% less long epithelial junction and approximately 20% more connective tissue in roots etched with EDTA. The statistically significant differences between citric-acid-treated surfaces (n=14) and control surfaces (n=11) were approximately 10% more connective tissue and 15% less long epithelial junction in the citric acid etched roots. Thus, etching with EDTA appeared to improve healing, avoiding the superficial necrotizing effect on exposed periodontal tissues by citric acid documented in previous studies. Although etching at present is not routinely applied in conventional periodontal therapy, future potential applications of etching at neutral pH may include exposure of the collagenous matrix of dentin for retention of biologically active substances, such as growth factors. Such treatment may be argued to produce a biocompatible surface more conducive to periodontal membrane cell colonization after removal of root-surface- associated smear without compromising the vitality of the surrounding periodontium.

Endodontic pathogens: propagation of infection through patent dentinal tubules in traumatized monkey teeth.

Periapical pathology indicating endodontic infection, when present in marginal periodontitis-affected teeth, has recently been shown to be an aggravating factor in progression of marginal destruction. This has been associated with patency of dentinal tubules in the tooth cervix, an area normally devoid of cementum following periodontal therapy. These studies are, however hampered by that only circumstantial evidence such as presence of periapical destruction have been applied as criteria of endodontic infection. The purpose of the present investigation was to study to what extent a predefined selection of endodontic pathogens inoculated in the root canal can influence periodontal pathology and healing in areas of the root covered by or devoid of cementum, using root resorption as a histomorphometric marker. Exposed dentine surfaces, in the present study showed significantly larger areas of resorption in infected roots compared to non-infected roots, while cementum surfaces showed an almost identical distribution of tissue reactions regardless of root canal infection or not. It was concluded that endodontic pathogens or their products were not able to penetrate the cementum barrier. The significantly larger areas of resorption on exposed dentine surfaces in infected roots compared to non-infected roots indicated that endodontic pathogens or their products could spread through dentinal tubules to a root surface void of cementum. Extrapolated to the marginal situation this indicated that endodontic pathogens in the root canal might be able to aggravate marginal infection in areas of root devoid of cementum.

The influence of endodontic infection on progression of marginal bone loss in periodontitis.

The purpose of the present investigation was to determine magnitude and rate of proximal radiographic attachment loss in relation to endodontic infection in periodontally involved teeth. The investigation was conducted as a retrospective longitudinal study on a periodontitis-prone randomly selected referral population, including 175 single-rooted, root-filled teeth in 133 patients. An observation period of at least 3 years was required. Periapical conditions of the selected sample at baseline and re-examination were evaluated on radiographs, independently by 3 investigators. Each single-rooted, root-filled tooth of the sample was given a score according to the combined registrations. Radiographic attachment level was measured as the distance between the most coronal point of the alveolar bone and the apex at the mesial and distal sides of the tooth, and expressed as relative radiographic attachment level (RRAL) (radiographic attachment level at baseline/root length) at proximal sites for every tooth. Multiple regression analysis was used to study change in RRAL over time. Teeth in periodontitis-prone patients with progressing periapical pathology indicating a continuous root canal infection were found to lose comparatively more radiographic attachment than teeth with no signs of periapical pathology or teeth with an established periapical destruction which subsided during the observation period. An approximate 3-fold amplification of the rate of marginal proximal radiographic bone loss by endodontic infection in periodontitis-prone patients was found with an average 0.19 mm/year, while 0.06 mm/year was lost for teeth without endodontic infection or subsiding endodontic involvement.

Endodontic pathogens in periodontal disease augmentation.

Periapical pathology indicating endodontic infection, when present in periodontitis-affected teeth, has recently been shown to be correlated to marginal periodontal breakdown. This has been associated with patency of dentinal tubules in the tooth cervix, an area normally devoid of cementum following periodontal therapy. These studies are, however hampered by that only circumstantial evidence such as presence of periapical destruction have been applied as criteria of endodontic infection. The aim of the present investigation was to assess the effects of endodontic pathogens on marginal periodontal wound healing on root surfaces devoid of cementum but surrounded by healthy periodontal membrane. Significant differences between infected and non-infected teeth were found with respect to pathological pocket and connective tissue: The experimental defects were covered by approximately 20% more pocket epithelium in infected teeth while defects in non-infected teeth showed approximately 10% more connective tissue coverage. It was concluded, that an intra-canal infection of endodontic pathogens stimulates epithelial downgrowth along denuded dentin surfaces with marginal communication. Extrapolated to the clinical situation, endodontic infections in periodontitis-prone patients may augment periodontitis propagation.

Long-time etching at low pH jeopardizes periodontal healing.

The purpose of the present investigation was to examine whether the immediate necrotizing effects of low pH etching agents also impair periodontal healing in the long-term perspective. It was concluded that long-time etching (3 min) at low pH of root surfaces surrounded by vital periodontal issues resulted in impaired periodontal healing. In contrast, short-time etching appeared to promote connective tissue formation by preventing epithelialization of the periodontal wound despite its low pH. However, clinical inferences should be drawn with caution from the present results, since healing results recorded at 8 weeks may not prove to be stable, especially for those cases sensitive to the immediate influence of marginal infection such as connective tissue attachments and epithelial junctions, unless optimal oral hygiene is maintained. Furthermore, the choice of acid may be of importance.

Proximal restorations and periodontal status.

The purpose of the present investigation was to evaluate the influence of overhanging marginal restorations on periodontal status and whether any such influence is modified by the patient's oral hygiene level and degree of radiographic attachment loss. The investigation was conducted as a retrospective study on a consecutive referral population. Periodontal pockets at proximal sites with marginal overhangs were significantly deeper (0.42 mm) compared to sites with metal restorations without overhangs. This difference was larger (0.62 mm) for sites with radiographic attachment loss < or = 6 mm, while no significant difference was found for sites with radiographic attachment loss > 6 mm. In patients with a mean radiographic attachment loss < or = 5 mm, an overhanging restoration margin was associated with a significantly increased loss of radiographic attachment (0.66 mm). It was concluded that the influence of a marginal overhang on pocket depth and radiographic attachment decreases with increasing loss of periodontal attachment in periodontitis-prone patients. The effect on pocket depth of a marginal overhang may act synergistically, potentiating the effect of poor oral hygiene.

Extraoral root lengthening with titanium screws.

The aim of the present study was to experimentally evaluate marginal and periapical healing in extracted and subsequently replanted teeth following extraoral cementing of apically exposed titanium root screws in the root canal. In 5 out of 6 replanted teeth, the periodontal tissues had healed with a normal periodontal membrane or healed surface resorptions indicating that only minor trauma had been inflicted during the extraoral procedure. In 3 out of 6 teeth, total or partial osseointegration of the titanium screws was seen, while a connective tissue capsule had formed around the remaining 3 screws. It was concluded that both of the healing results described in the present study, osseointegration and connective capsule formation, may be regarded as acceptable as long as inflammation is prevented, although it remains to be shown which one represents the end-point.

Differential periodontal temperature measurements in the assessment of periodontal disease activity: an experimental and clinical study.

The difference in surface temperatures between the bottom of periodontal pockets and the attached gingiva adjacent to the openings of the pockets were determined both in monkeys with experimental marginal periodontitis, and clinically in patients with marginal periodontitis. For this purpose a custom-made, temperature-measuring device was developed which enabled immediate recording of temperature differences as well as periodontal pocket depths, bleeding, and attachment levels. The measurements were performed periodically. The differential temperature measurements were correlated to change in periodontal attachment over time. It was shown that differential periodontal temperatures are well correlated to change in periodontal attachment over time. It was furthermore concluded that differential periodontal temperature measurements have the potential of serving as a predictor of activity of marginal periodontitis. However, more extensive data are required to assess the sensitivity and specificity of the method.