Periodontal tissue-vitality after different etching modalities

Cytotoxicity of V-Prep Versus Phosphoric Acid Etchant on Oral Gingival Fibroblasts

The most used etchant in dental daily practice is the phosphoric acid (P.A.; 37%). However, acid etchants can induce necrosis on the oral mucosa and cause the ulceration of periodontal tissue when a rubber dam is not used. V-prep is a new practical alternative, and it has satisfactory results. It is used as a preparation before the application of a resin-modified glass ionomer composite (RMGIC) to bond the orthodontic brackets. The aim of this study was to investigate the effect of the V-prep on oral gingival fibroblasts cells by comparing the cell damage and cell viability after the use of V-prep and a conventional phosphoric acid etchant with different application times and concentrations. Therefore, Gingival fibroblasts passage 6 (GFP6) was grown and treated with an acid etchant and V-prep at three different concentrations (1:1, 1:2 and 1:10) for two different application durations (30 s and 1 min). The morphological changes, cell death and cell viability were assessed. Pyknosis, karyolysis, nucleus reversible and irreversible damages and membrane destruction were observed for both of the etchants at the higher concentrations and longer application durations. Mann-Whitney U-tests were used for the statistical analyses. The application of the V-prep for 30 s showed better values than the acid etchant did in the cell damage analysis and cell viability analysis (p = 0.03). V-prep at a 1:10 concentration applied for a 30 s duration can preserve the viability of gingival fibroblasts cells up to 100%. The toxicity of V-prep is equal or lower than the toxicity of the acid etchant that is commonly used in dentistry. Thus, the V-prep can be used with precautions intra-orally, and it should be applied on the enamel as a gel for 30 s only before it is rinsed and removed.

Effect of root surface conditioning on gingival recession coverage with a connective tissue graft. A retrospective comparative study of three different agents

OBJECTIVE

Different root modifiers have been proposed in the literature with an attempt to improve the healing process and the success rate of root coverage procedures. The aim of the present retrospective study was to evaluate the effect of three different types of root surface conditioning, namely, tetracycline (TTC), ethylene-di-amino-tetra-acetic acid (EDTA) and saline, on the outcome of root coverage procedures applying the same surgical technique.

MATERIALS AND METHODS

Twenty-nine patients with 60 Classes I, II, or III recession defects were treated using connective tissue with a partial-thickness double-pedicle graft. In 21 recession defects root surface was treated with TTC and, in other 21, with EDTA, while in the remaining, saline solution was applied. Statistical analysis consisted of descriptive statistics and Kruskal-Wallis, Mann-Whitney, and chi-square tests.

RESULTS

Differences between pre- and postoperative values were statistically significant only within but not between groups. Mean root coverage was 73.25%, 69.19%, and 82.17% in the TTC, the EDTA, and the saline groups, respectively. The study revealed no statistically significant differences for all evaluated parameters between groups.

CONCLUSION

Within the limits of this study, root conditioning, prior to root coverage procedures, does not significantly affect their outcome.

CLINICAL SIGNIFICANCE

Clinical outcome of root coverage procedures is not related to the type of root surface conditioning.

Iatrogenic acid-induced gingival recession during crown cementation: A case report

Accidental contact of various chemicals in dentistry may cause damage to the gingiva. A male patient presented for a full mouth rehabilitation with ceramic crowns. The patient underwent the steps of ceramic crown preparation uneventfully. At the time of crown delivery, cotton rolls were placed in several vestibular areas for isolation. They were regularly changed during different steps of etching and cementation process, which included the use of Multilink Primer B (Ivoclar Vivadent™). On removal of the cotton roll in the area of upper right canine, the gingival tissues appeared blanched and grayish white. The cotton roll was found to have absorbed some etching material in it. As the patient was asymptomatic, he was dismissed. Two weeks later, the patient presented with inflammation and gingival recession in the same area. Initially, he was treated palliatively, and subsequently, he received a connective tissue graft on the upper right canine. This case report showed that acid etching material used during the prosthodontic cementation may have caused a gingival recession, which was successfully treated with tunnel flap and connective tissue graft. Optimal isolation of the operative field should be performed to avoid this problem.

A comparative analysis of root surface biomodification with ethylene diamine tetra acetic acid and tetracycline hydrochloride: An in vitro scanning electron microscopic study

BACKGROUND

The outcome of periodontal regenerative therapy depends upon the of the biocompatibility root surfaces to the regenerating periodontal tissues. This in vitro scanning electron microscopic (SEM) study was designed to evaluate and compare the demineralizing efficacy of ethylene diamine tetra acetic acid (EDTA), with that of tetracycline hydrochloride applied on to the mechanically treated root surfaces of periodontally involved tooth.

METHODS

Forty specimens were prepared from teeth extracted due to advanced periodontal disease and divided into two groups. The study group was treated with an EDTA solution (pH 7.4) and the control group was treated with a tetracycline hydrochloride solution (pH 1.8). The photomicrographs obtained were assessed for presence of smear layer, number of exposed dentinal tubules, area occupied by tubule orifices along with intertubular surface appearance. The results thus obtained were analyzed statistically.

RESULTS

Both EDTA and tetracycline were effective in removing the smear layer and the exposure of the number of dentinal tubules. The diameters of the tubules and thereby the surface area occupied by the tubule orifices in the EDTA treated group were significantly greater than the tetracycline HCL treated group (p < 0.05).

CONCLUSION

The EDTA produced better effects than tetracycline by providing more demineralized area and collagen exposure at a neutral pH.

pH-dependent antibacterial effects on oral microorganisms through pure PLGA implants and composites with nanosized bioactive glass

Biomaterials made of biodegradable poly(α-hydroxyesters) such as poly(lactide-co-glycolide) (PLGA) are known to decrease the pH in the vicinity of the implants. Bioactive glass (BG) is being investigated as a counteracting agent buffering the acidic degradation products. However, in dentistry the question arises whether an antibacterial effect is rather obtained from pure PLGA or from BG/PLGA composites, as BG has been proved to be antimicrobial. In the present study the antimicrobial properties of electrospun PLGA and BG45S5/PLGA fibres were investigated using human oral bacteria (specified with mass spectrometry) incubated for up to 24 h. BG45S5 nanoparticles were prepared by flame spray synthesis. The change in colony-forming units (CFU) of the bacteria was correlated with the pH of the medium during incubation. The morphology and structure of the scaffolds as well as the appearance of the bacteria were followed bymicroscopy. Additionally, we studied if the presence of BG45S5 had an influence on the degradation speed of the polymer. Finally, it turned out that the pH increase induced by the presence of BG45S5 in the scaffold did not last long enough to show a reduction in CFU. On the contrary, pure PLGA demonstrated antibacterial properties that should be taken into consideration when designing biomaterials for dental applications.

Failure of treatment of impacted canines associated with invasive cervical root resorption

OBJECTIVES

To propose invasive cervical root resorption (ICRR) as an unrecognized and/or overlooked etiologic factor in the failure of response of an impacted tooth to orthodontic traction and to underline the importance of cone beam computerized tomography (CBCT) for early and accurate diagnosis of ICRR.

MATERIALS AND METHODS

Fourteen patients (age 13-21 years) with impacted canines (15 canines) that had failed to respond to orthodontic forces and that exhibited ICRR formed the case series for this investigation. The initial diagnosis, treatment, clinical and radiographic expression of failure, and adverse effects on adjacent teeth were analyzed.

RESULTS

Initial diagnosis had been performed on plane radiographs. The orthodontist was absent during surgery in 11 patients. Nine canines had been exposed by open procedures. ICRR was not related to the severity of impaction. Its diagnosis was made on existing radiographs, new films, and/or new CBCT. The severity of the lesions was Class 3 or 4, and the teeth were finally extracted. Loss of anchorage characterized 11 patients. Apical resorption of the roots of adjacent teeth was diagnosed in 9 patients.

CONCLUSIONS

ICRR is a frequently undiagnosed or unrecognized cause of failure of orthodontic resolution of impacted canines and should be distinguished from replacement resorption. CBCT should be used for its early detection and accurate assessment of potential damage to adjacent anchor teeth.

Comparação in vitro da eficácia de diferentes formulações do gel de EDTA 24% no condicionamento da superfície radicular

INTRODUÇÃO: A biomodificação radicular visa a alterar a superfície radicular para auxiliar no reparo das estruturas periodontais de suporte destruídas pela doença periodontal. OBJETIVO: Avaliar por meio de microscopia eletrônica de varredura a eficácia do condicionamento químico com gel de EDTA 24% na remoção de smear layer e na exposição de fibras colágenas, verificando-se diferentes marcas comerciais, modos e tempos de aplicação. MATERIAL E MÉTODO: Um total de 225 amostras foram obtidas e distribuídas aleatoriamente em cinco grupos: soro fisiológico (controle); EDTA 24% (Farmácia Santa Paula); EDTA-T 24% (Farmácia Santa Paula); EDTA 24% (PrefGel; Straumann); EDTA 24% (Biodinâmica). As amostras de cada grupo foram redistribuídas aleatoriamente em subgrupos (n = 5) e condicionadas com os diferentes géis de EDTA nos tempos de 1, 2 e 3 minutos, e nos modos de aplicação tópica, fricção vigorosa e fricção suave. Os testes de Kruskal-Wallis e Dunn (p < 0,05) foram utilizados e aplicados separadamente para os fatores: marca comercial, tempo e modo de aplicação. RESULTADO: A análise estatística revelou que o gel de EDTA 24% da Biodinâmica promoveu a menor remoção de smear layer. Não foram detectadas diferenças estatísticas para os tempos de aplicação. O modo de aplicação fricção suave resultou em menor quantidade de smear layer residual. CONCLUSÃO: Todos os géis de EDTA 24% utilizados foram eficazes na remoção de smear layer e na exposição de fibras colágenas, independentemente do tempo de aplicação; no entanto, o modo de fricção suave foi mais efetivo. Na análise comparativa entre os produtos, o EDTA da Biodinâmica foi menos efetivo, já que promoveu menor remoção de smear layer e exposição de fibras colágenas.

Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning

Objective

The aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning.

Material and Methods

A total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group). After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained.

Results

Brushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples.

Conclusion

Despite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning.

Comparison among four commonly used demineralizing agents for root conditioning: a scanning electron microscopy

Dental roots that have been exposed to the oral cavity and periodontal pocket environment present superficial changes, which can prevent connective tissue reattachment. Demineralizing agents have been used as an adjunct to the periodontal treatment aiming at restoring the biocompatibility of roots.

OBJECTIVE

This study compared four commonly used demineralizing agents for their capacity of removing smear layer and opening dentin tubules.

METHODS

Fifty fragments of human dental roots previously exposed to periodontal disease were scaled and randomly divided into the following groups of treatment: 1) CA: demineralization with citric acid for 3 min; 2) TC-HCl: demineralization with tetracycline-HCl for 3 min; 3) EDTA: demineralization with EDTA for 3 min; 4) PA: demineralization with 37% phosphoric acid for 3 min; 5) CONTROL: rubbing of saline solution for 3 min. Scanning electron microscopy was used to check for the presence of residual smear layer and for measuring the number and area of exposed dentin tubules.

RESULTS

Smear layer was present in 100% of the specimens from the groups PA and control; in 80% from EDTA group; in 33.3% from TC-HCl group and 0% from CA group. The mean numbers of exposed dentin tubules in a standardized area were: TC-HCl=43.8±25.2; CA=39.3±37; PA=12.1±16.3; EDTA=4.4±7.5 and CONTROL=2.3±5.7. The comparison showed significant differences between the following pairs of groups: TC-HCl and CONTROL; TC-HCl and EDTA; CA and CONTROL; and CA and EDTA. The mean percentages of area occupied by exposed dentin tubules were: CA=0.12±0.17%; TC-HCl=0.08±0.06%; PA=0.03±0.05%; EDTA=0.01±0.01% and CONTROL=0±0%. The CA group differed significantly from the others except for the TC-HCl group.

CONCLUSION

There was a decreasing ability for smear layer removal and dentin tubule widening as follows: AC>TC-HCl>PA>EDTA. This information can be of value as an extra parameter for choosing one of them for root conditioning.

A scanning electron microscopy study of diseased root surfaces conditioned with EDTA gel plus Cetavlon after scaling and root planing

In the present investigation, a scanning electron microscopy analysis was performed to evaluate the effects of the topical application of ethylenediaminetetraacetic acid (EDTA) gel associated with Cetavlon (EDTAC) in removing the smear layer and exposing collagen fibers following root surface instrumentation. Twenty-eight teeth from adult humans, single rooted and scheduled for extraction due to periodontal reasons, were selected. Each tooth was submitted to manual (scaling and root planing) instrumentation alone or combined with ultrasonic instruments, with or without etching using a 24% EDTAC gel. Following extraction, specimens were processed and examined under a scanning electron microscope. A comparative morphological semi-quantitative analysis was performed; the intensity of the smear layer and the decalcification of cementum and dentinal surfaces were graded in 12 sets using an arbitrary scale ranging from 1 (area covered by a smear layer) to 4 (no smear layer). Root debridement with hand instruments alone or combined with ultrasonic instruments resulted in a similar smear layer covering the root surfaces. The smear layer was successfully removed from the surfaces treated with EDTAC, which exhibited numerous exposed dentinal tubules and collagen fibers. This study supports the hypothesis that manual instrumentation alone or instrumentation combined with ultrasonic instrumentation is unable to remove the smear layer, whereas the subsequent topical application of EDTAC gel effectively removes the smear layer, uncovers dentinal openings and exposes collagen fibers.

Root surface biomodification with EDTA for the treatment of gingival recession with a semilunar coronally repositioned flap

BACKGROUND

The purpose of this randomized clinical trial was to evaluate the outcome of gingival recession therapy using the semilunar coronally repositioned flap (SCRF) with or without EDTA application for root surface biomodification.

METHODS

Fifteen patients with bilateral Miller Class I buccal gingival recessions (< or =4.0 mm) were selected. Thirty teeth with recessions were assigned randomly to receive the semilunar coronally repositioned flap with (SCRF-E group) or without (SCRF group) the application of an EDTA gel. Recession height (RH), recession width (RW), width (WKT) and thickness of keratinized tissue, probing depth, and clinical attachment level (CAL) were measured at baseline and 6 months post-surgery. Patient perception of root sensitivity and postoperative pain also was evaluated.

RESULTS

Both treatments yielded significant improvements in terms of RH and RW decrease and CAL gain compared to baseline values. For SCRF-E and SCRF, the average root coverage was 70.2% and 90.1%, respectively (P = 0.01), and the complete root coverage was 40.0% and 66.7%, respectively. Only the SCRF group had a significant (P <0.05) increase in WKT. The SCRF group showed a greater reduction (P <0.05) in RW and RH compared to the SCRF-E group. No patient in either group reported any pain during the postoperative course; however, 6 months later, patients in the SCRF-E group complained more of residual or new root sensitivity compared to patients in the SCRF group.

CONCLUSION

The use of EDTA gel as a root surface biomodifier agent negatively affected the outcome of root coverage with the SCRF.

Effects of EDTA Gel Preconditioning of Periodontally Affected Human Root Surfaces on Chlorhexidine Substantivity – An SEM Study

BACKGROUND

Infection control is an important requirement during the early stages of periodontal healing. This study was performed to assess the preconditioning effect of EDTA gel on chlorhexidine (CHX) substantivity to periodontally involved root surfaces.

METHODS

Eighty patients with severe chronic periodontitis were enrolled in this study. Following cause-related therapy, patients were divided randomly into four groups. Each group consisted of 20 subjects with one tooth that was diagnosed as hopeless and designated for extraction. In group 1 (G1), selected periodontal pockets were filled with a placebo gel in a silica base for 2 minutes. Exposed roots in group 2 (G2) were etched for 2 minutes with a neutral EDTA conditioning agent, followed by pocket fill with the placebo gel. Pockets in group 3 (G3) were filled with 0.12% CHX digluconate gel in a silica base. Exposed roots in group 4 (G4) were etched for 2 minutes with a neutral EDTA conditioning agent, followed by pocket fill with the CHX gel. Four teeth from each group were extracted immediately and at 3, 12, 24, and 48 hours for SEM evaluation.

RESULTS

G1 and G2 specimens showed no evidence of silica adherent to any of the examined root surfaces. At 3 hours following CHX gel application, G3 specimens showed marked reduction in CHX-coated silica. At 24 and 48 hours following EDTA and CHX gel application, G4 specimens demonstrated adherent CHX-coated silica particles despite the reclogging of the tubule orifices.

CONCLUSION

EDTA and CHX gel root conditioning is a valuable regimen that improves CHX substantivity to periodontally involved root surfaces.

Histological analysis of effects of 24% EDTA gel for nonsurgical treatment of periodontal tissues

The aim of this study was to investigate, by means of histological and histomorphometric analysis, the effects of 24% ethylenediaminetetraacetic acid (EDTA) gel in periodontal tissue when used in combination with conventional periodontal treatment. Periodontitis was induced in the 2nd upper left permanent molars of 45 male Wistar rats by means of ligature. After 5 weeks, this was removed and debridement was performed. The animals were then randomly divided into 3 groups; group 1: mechanical treatment, group 2: mechanical treatment and EDTA gel application for 2 min, and group 3: mechanical treatment and placebo gel application for 2 min. After the treatment, rinsing was done with 0.9% saline solution for 1 min in all cases, followed by root notching in the deepest part of the pocket. After 4, 10, and 28 days the animals were sacrificed. The averages obtained were evaluated by means of test two-way analysis of variance (ANOVA) and Tukey statistical tests (P < 0.05). The results showed that with respect to the type of treatment employed, there were no statistically significant differences in the vitality of the periodontal tissue. It was concluded that 24% EDTA gel did not interfere with periodontal tissue repair when used in combination with conventional periodontal treatment.

Effect of EDTA Root Conditioning on the Healing of Intrabony Defects Treated With an Enamel Matrix Protein Derivative

BACKGROUND

Regenerative periodontal therapy with an enamel matrix protein derivative (EMD) has been shown to promote regeneration in intrabony periodontal defects. However, in most clinical studies, root surface conditioning with EDTA was performed in conjunction with the application of EMD, and, therefore, it cannot be excluded that the results may also be attributable to the effect of the root conditioning procedure. The purpose of this study was to determine the effect of root conditioning on the healing of intrabony defects treated with EMD.

METHODS

Twenty-four patients, each of whom exhibited one deep intrabony defect, were randomly treated with either open flap debridement (OFD) followed by root surface conditioning with EDTA and application of EMD (OFD+EDTA+EMD) or with OFD and application of EMD only (OFD+EMD). The following parameters were recorded at baseline and at 1 year: plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), and clinical attachment level (CAL).

RESULTS

No differences in any of the investigated parameters were observed at baseline between the two groups. Healing was uneventful in all patients. At 1 year after therapy, the OFD+EDTA+EMD group showed a reduction in mean PD from 9.3+/-1.3 mm to 4.0+/-0.9 mm (P<0.001), and mean CAL changed from 10.8+/-2.2 mm to 7.1+/-2.8 mm (P<0.001). In the OFD+EMD group, mean PD was reduced from 9.3+/-1.2 mm to 4.2+/-0.9 mm (P<0.001), and a change in mean CAL from 11.0+/-1.7 mm to 7.3+/-1.6 mm (P<0.001). There were no significant differences in any of the investigated parameters between the two groups.

CONCLUSION

In intrabony defects, regenerative surgery including OFD+EDTA+EMD failed to show statistically significant differences in terms of PD reduction and CAL gain compared to treatment with OFD+EMD.

Tetracycline at Subcytotoxic Levels Inhibits Matrix Metalloproteinase-2 and -9 But Does Not Remove the Smear Layer

BACKGROUND

The antibacterial and anticollagenolytic properties of tetracycline (TCN) are valuable in periodontal therapy, and TCN treatment can remove the smear layer following root instrumentation. However, recent reports pointing to cytotoxic effects of several acids prompted this study to define TCN concentrations that are anticollagenolytic and remove the smear layer, but have low cytotoxicity.

METHODS

Human gingival (hGF) and periodontal ligament (hPDL) cells were treated short- (3 minutes) or long-term (24 hours) with TCN to determine concentrations yielding 50% (TD(50)) and 90% (TD(10)) cell survival. Activity assays measured TCN concentrations with half-maximal inhibition (IC(50)) of matrix metalloproteinase- 2 and -9 (MMP-2 and -9). Finally, we analyzed the effects of TCN with high (75 mg/ml) or low (1 mg/ml) cytotoxicity on the smear layer by scanning electron microscopy (SEM).

RESULTS

The TD(50) for TCN after short-term treatment was 4 mg/ml for both hGF and hPDL. Ninety percent of the cells survived 0.2 mg/ml. With long-term treatment, the TD(50) for hGF and hPDL was 70 and 30 microg/ml, respectively, and the TD(10) was 20 and 5 microg/ml. HGF and hPDL recovered from the 3-minute treatment with 1 mg/ml, but not from concentrations exceeding 3 and 9 mg/ml, respectively. The IC(50) was 25 microg/ml for both MMP-2 and MMP-9. Whereas 75 mg/ml TCN removed the smear layer, 1 mg/ml TCN had no effects.

CONCLUSIONS

Tetracycline has significant cytotoxicity on periodontal cells. Since non-cytotoxic concentrations of TCN inhibited MMP-2 and -9 but had no effects on the smear layer, TCN is not recommended for root surface treatment.

Healing of periodontal defects treated with enamel matrix proteins and root surface conditioning—an experimental study in dogs

Application of enamel matrix proteins has been introduced as an alternative method for periodontal regenerative therapy. It is claimed that this approach provides periodontal regeneration by a biological approach, i.e. creating a matrix on the root surfaces that promotes cementum, periodontal ligament (PDL) and alveolar bone regeneration, thus mimicking the events occurring during tooth development. Although there have been numerous in vitro and in vivo studies demonstrating periodontal regeneration, acellular cementum formation and clinical outcomes via enamel matrix proteins usage, their effects on the healing pattern of soft and hard periodontal tissues are not well-established and compared with root conditioning alone. In the present study, the effects of Emdogain (Biora, Malmö, Sweden), an enamel matrix derivative mainly composed of enamel matrix proteins (test), on periodontal wound healing were evaluated and compared with root surface conditioning (performed with 36% orthophosphoric acid) alone (control) histopathologically and histomorphometrically by means of the soft and hard tissue profile of periodontium. An experimental periodontitis model performed at premolar teeth of four dogs were used in the study and the healing pattern of periodontal tissues was evaluated at days 7, 14, 21, 28 (one dog at each day), respectively. At day 7, soft tissue attachment evaluated by means of connective tissue and/or epithelial attachment to the root surfaces revealed higher connective tissue attachment rate in the test group and the amount of new connective tissue proliferation in the test group was significantly greater than the control group (p<0.01). New bone formation by osteoconduction initiated at day 14 in the test and control group. At day 21, the orientation of supra-alveolar and PDL fibers established, and new cementum formation observed in both groups. At day 28, although regenerated cementum was cellular in all of the roots in the control samples, an acellular type of cementum (1.32+/-0.83 mm in length and 3.16+/-0.23 microm in width) was also noted in six roots of test samples with an inconsistent distribution on the root surfaces. The amount of new cementum was significantly higher in the test group than the control group samples (p<0.01). The width of the cellular cementum in the control group was more than the cellular cementum in the test group, but the difference was not statistically significant (p>0.05). A firm attachment of acellular cementum to the root dentin with functional organization of its collagen fibers was noted, and, the accumulation and organization of cellular cementum in the control group was more irregular than the cellular cementum formed in the test group. The amount of new bone was 2.41+/-0.75 mm in the test and 1.09+/-0.46 mm in the control group at day 28. The rate of bone maturation (the number of osteons) was found higher in the test group (10.75+/-0.85) than the control group (5.50+/-0.86). Under the limitations of the study, our results reveal that when compared with root surface conditioning, enamel matrix proteins have more capacity for stimulating periodontal regeneration via their positive effects on root surfaces, i.e. inhibition of gingival epithelium down growth and stimulation of connective tissue proliferation and attachment to the root surfaces during wound healing. An acellular type of cementum regeneration and new alveolar bone formation by an accelerated osteoconductive mechanism are also achieved with application of enamel matrix proteins.

Evaluation of enamel matrix derivative as an adjunct to non-surgical periodontal therapy

OBJECTIVES

The aim of this study was to evaluate the adjunctive use of enamel matrix derivative (EMD) on periodontal healing following nonsurgical periodontal therapy (scaling and root planing - SRP).

MATERIAL AND METHODS

The study was performed as an intraindividual, longitudinal trial of 3 months duration with a double-blinded, split-mouth, controlled, and randomized design. Twenty-two patients with moderate to severe chronic periodontitis were enrolled in the study. In each patient, two sites with pocket depths >/=5 mm and with radiographic angular bone defects >3 mm were selected. Baseline examination included measurement of probing pocket depth (PPD) and clinical attachment levels (CAL). The presence or absence of plaque and bleeding on probing at selected sites was also recorded. Following initial examination, full-mouth SRP was performed. Study sites were then treated with 24% EDTA for 2 min, followed by thorough irrigation with sterile saline. The sites were then randomized. The experimental site received subgingival application of enamel matrix derivative (Emdogain, BIORA AB, Malmo, Sweden). The control site received no additional treatment. At 3 months, all sites were re-examined. The response to therapy in experimental and control sites was evaluated, using change in probing depth and CAL as the primary outcome variables. Statistical analysis (paired t-tests) was used to compare response to treatment in control versus experimental sites.

RESULTS

Statistically significant changes in PPD and CAL were seen in both treatment groups from baseline to 3 months. The mean PPD reduction was 2.3+/-0.5 mm for control sites and 2.0+/-0.3 mm for experimental sites. The mean CAL gain was 1.8+/-0.4 mm for control sites, and 1.4+/-0.3 mm for experimental sites. Statistical analysis, however, revealed no significant difference in PPD reduction or CAL gain between experimental and control groups (p>0.4). In addition, no difference was found between treatment groups in bleeding or plaque indices at 3 months.

CONCLUSION

The findings from the present study do not support the use of EMD during routine, nonsurgical debridement of periodontal pockets as measured 3 months post SRP.

[Scanning electron microscopy analysis on root surfaces before and after scalling and citric acid and EDTA conditioning: an "in vitro" study]

The most benefic root surface for periodontal regeneration has not been known. Looking for this surface this study used 14 human teeth prepared as testing corpus and treated with scaling and conditioning with citric acid and EDTA, and analysed in scanning electron microscopy. The health teeth surfaces showed regular grains representing broken periodontal ligament fibers by exodontics. The contaminated surfaces showed calculus masses, very porous, and resorption areas. When scalled with hand curettes the surfaces was covered by smear layer. The citric acid conditioning was efficient on smear layer removal, as well as the EDTA gel, and the EDTA liquid solution was not efficient on smear removal.

A retrospective case series comparing the use of demineralized freeze-dried bone allograft and freeze-dried bone allograft combined with enamel matrix derivative for the treatment of advanced osseous lesions

BACKGROUND

Combined regenerative approaches have been used for treating advanced osseous lesions around teeth. The aim of combining treatments is to enhance both clinical predictability and regenerative outcome compared to a monotherapeutic approach. This case series from a private practice reports on the clinical efficacy of an enamel matrix derivative (EMD) combined with either demineralized freeze-dried bone allograft (DFDBA) or freeze-dried bone allograft (FDBA) in the treatment of advanced infrabony lesions. The advanced lesions were veneered by a rapidly formed absorbable polymer barrier of poly(DL-lactide) to enhance graft containment.

METHODS

A total of 22 consecutive patients, each contributing one infrabony lesion, are reported. After patients completed presurgical preparation, the infrabony lesions were surgically treated with a combined approach that included root surface treatment with citric acid. The two groups differed in their composite graft; one received DFDBA-EMD (n = 10) and the other received FDBA-EMD (n = 12). Patients followed a stringent postoperative protocol and were evaluated 6 months postsurgery. Clinical outcomes were assessed by changes in clinical attachment level (CAL) and probing depth (PD) from pretreatment. Surgical re-entry of several sites was possible in each group.

RESULTS

CAL at pretreatment measured 9.2 +/- 1.3 mm and 9.1 +/- 1.9 mm for DFDBA-EMD and FDBA-EMD groups, respectively, with corresponding PD of 8.4 +/- 1.6 mm and 8.9 +/- 2.0 mm for each group. At 6 months post-treatment, CALs were reduced to 4.7 +/- 1.3 mm and 3.8 +/- 1.0 mm for DFDBA-EMD and FDBA-EMD groups, respectively; with corresponding PD decreased to 3.0 +/- 0.8 mm and 3.2 +/- 1.0 mm. Relative improvements in CAL for the DFDBA-EMD and DFDBA-EMD groups were 49.1% +/- 11.0% and 57.3% +/- 9.4%, respectively (P <0.07).

CONCLUSIONS

This case series demonstrates the clinical benefits of using a combined therapeutic approach in which a biologic mediator (EMD) was combined with either DFDBA or FDBA. In this limited case series, a trend was observed towards greater improvement in clinical attachment level gain in advanced infrabony defects when EMD was combined with FDBA as compared to DFDBA. Larger prospective controlled clinical trials are needed to determine if differences exist in the relative efficacy of DFDBA versus FDBA in combination with EMD.

Hard tissue formation on dentin surfaces applied with recombinant human bone morphogenetic protein-2 in the connective tissue of the palate

The purpose of this study was to evaluate whether hard tissue might be formed on dentin surfaces applied with recombinant human bone morphogenetic protein-2 (rhBMP-2) in palatal connective tissue. Fifty-eight dentin blocks were prepared from rat roots, demineralized with 24% EDTA (pH 7.0), applied with 0, 50 and 100 microgram/ml rhBMP-2, and labeled as groups 0, 50 and 100. The dentin blocks were then transplanted into palatal connective tissue of rats, and specimens were prepared at two and four weeks after surgery for histologic and histomorphometric examinations. The results showed that the percentage of newly formed hard tissue in relation to the total dentin block surface length in groups 0, 50 and 100 was 0.0%, 2.8% and 4.4% at two weeks, and 0.0%, 1.6% and 12.8% at four weeks, respectively. New hard tissue formation in groups 50 and 100 was significantly promoted as compared to group 0 (p < 0.01). These findings thus indicate that rhBMP-2 application to dentin enhanced new hard tissue formation on dentin surfaces in the connective tissue of the palate.

A study of attached and oriented human periodontal ligament cells to periodontally diseased cementum and dentin after demineralizing with neutral and low pH etching solution

BACKGROUND

This study aimed to evaluate quantitatively the migrated, attached, and oriented human periodontal ligament cells (HPLC) to periodontally diseased cementum and dentin after demineralization with low and neutral pH etching solution.

METHODS

Human teeth, extracted due to periodontal diseases, were scaled and root planed so that cementum remained on one longitudinal half of the root and dentin was exposed on the other half. Forty root slices of 200 microm thickness, obtained from the mid-third of these roots, were divided into four groups: group 1, demineralized with a saturated solution of citric acid (pH 1.20); group 2, with 24% EDTA (pH 7.04); group 3, with tetracycline HCl 100 mg/ml (pH 2.00); and group 4, only scaled and root planed (control). Root slices were placed over the confluent HPLC in 35 mm culture dishes and incubated. Phase contrast microscopic photographs of attached and oriented refractile HPLC to root surfaces were taken at days 1, 3, and 7. Quantitative analysis of attached and oriented HPLC from these photographs was done using special software.

RESULTS

The results showed no significant difference in the attachment and orientation index of HPLC to cementum compared to dentin in any method of demineralization at each time point (P >0.05), although there was a significantly higher cell attachment and orientation index to demineralized dentin with EDTA and citric acid than to non-etched dentin and to all 3 demineralized cementum surfaces compared to non-etched cementum (P<0.05).

CONCLUSIONS

EDTA and citric acid demineralization may enhance HPLC attachment and orientation to the root surface, and it is not always necessary to remove excessive cementum when the demineralizing procedure is used.

Effect of recombinant human platelet-derived growth factor-BB and bone morphogenetic protein-2 application to demineralized dentin on early periodontal ligament cell response

The purpose of this study is to investigate the early responses of human periodontal ligament cells attached to recombinant human platelet-derived growth factor-BB and bone morphogenetic protein-2 applied EDTA-demineralized dentin. One hundred and seventy-four root-planed flat dentin blocks were prepared from the mid-third of periodontally diseased human tooth roots. After demineralization with 24% EDTA (pH 7.02) 120 dentin blocks were treated with 0.5 and 1 microgram/ml rhPDGF-BB, 1 and 3 micrograms/ml rhBMP-2 and only MEM as control (24/group). Human periodontal ligament cells (HPLC) were seeded on these dentin surfaces and incubated. The alkaline phosphatase (ALP) activity and protein concentration of the attached cell were assessed at d 2, 4 and 7. Fifty-four dentin blocks were seeded with HPLC after application of 1 microgram/ml rhPDGF-BB, 3 micrograms/ml rhBMP-2 and MEM (18/group) and then incubated. At d 2, 4 and 7, the attached cells were stained and counted under light microscope. The results showed a significant increase of protein concentration and cell number in PDGF-BB treated groups than control (p < 0.05, p < 0.01) but not the ALP activity, and a significant increase of ALP activity was observed in BMP-2 treated groups than control (p < 0.05) but protein concentration and cell number remained almost the same over time. Thus, rhPDGF-BB and rhBMP-2 application to EDTA demineralized dentin surfaces promote the early human periodontal ligament cell responses by increasing cell proliferation and differentiation, respectively, which would ultimately enhance periodontal regeneration.

The effects of extracellular citric acid acidosis on the viability, cellular adhesion capacity and protein synthesis of cultured human gingival fibroblasts

Root surface demineralization is widely used as an adjunct to periodontal treatment. To clarify the influence of citric acid root conditioning on periodontal wound healing, the effects of citric acid and associated extracellular acidosis on the viability (MTT assay), attachment and protein synthesis ([3H]-proline incorporation into trichloroacetic acid-precipitated proteins) of human gingival fibroblasts (GF) were investigated. A concentration of 47.6 mmol/L of citric acid (pH 2.3) in water led to total cell death within three minutes of incubation. Media containing 23.8 mmol/L and 47.6 mmol/L of citric acid exerted strong cytotoxicity (47 to 90 per cent of cell death) and inhibited protein synthesis (IC50 = 0.28 per cent) of GF within three hours of incubation. Incubation of cells in a medium containing 11.9 mmol/L of citric acid also suppressed the attachment and spreading of fibroblasts on culture plates and Type I collagen, with 58 per cent and 22 per cent of inhibition, respectively. Culture medium supplemented with 11.9, 23.8 and 47.6 mmol/L of citric acid also led to extracellular acidosis by decreasing the pH value from 7.5 to 6.3, 5.2 and 3.8, respectively. In addition, it was confirmed that the toxic effect of media containing citric acid was due to their acidity rather than the citrate content. Most of the citric acid-induced cell death could be prevented by adjusting the pH value of the culture medium to pH 7.5. Sodium citrate, at a concentration of 47.6 mmol/L, also exerted little cytotoxicity. The results suggested that toxicity of citric acid in specific stages of the healing process must be considered prior to its clinical application. Careful management of citric acid in order to avoid contact with tissue or the development of other demineralizing agents is important in enhancing periodontal wound healing.

Root conditioning using EDTA gel as an adjunct to surgical therapy for the treatment of intraosseous periodontal defects

The aim of this clinical study was to compare the treatment outcome following root surface conditioning using an EDTA gel preparation in conjunction with surgical therapy with that following conventional flap surgery in periodontal intraosseous defects. 36 patients, each of them contributing one intraosseous defect > or =4 mm in depth participated. Defect sites had a probing pocket depth > or =5 mm and bled on probing following hygienic treatment phase. No furcation involvement or endodontic complications were present. In the EDTA group, 18 consecutive patients, defects were treated by root conditioning with EDTA gel for 3 minutes in combination with surgical therapy. In the control group, 18 patients, conventional flap surgery was performed without root conditioning. Chlorhexidine rinsings 0.2% were prescribed following surgery for 2-3 weeks with modified oral hygiene instruction. A strict recall program was implemented including professional prophylaxis and oral hygiene reinforcement every 4-6 weeks until 6-month re-evaluation. Baseline probing pocket depths and defect depths of 7.1+/-1.3 mm and 6.9+/-1.6 mm in the EDTA group and 7.6+/-1.9 mm and 6.6+/-1.7 mm, respectively, in the control group were measured. 6-month clinical results showed a significant probing attachment level gain of 1.8+/-1.5 mm and 1.0+/-1.7 mm in the EDTA and control groups respectively. A probing bone gain of 1.0+/-1.3 mm in the EDTA group was measured with a non-significant gain of 0.4+/-1.2 mm in the control group. Radiographic analysis confirmed these results. There were no statistically significant differences in treatment outcome between the group treated by root conditioning in combination with flap surgery and conventional flap surgery alone.

Guided tissue regeneration update

The ultimate goal of periodontal therapy is to restore periodontal tissues lost through disease or trauma. The most predictable way to accomplish this goal is by guided tissue regeneration (GTR). The principle of GTR is to give preference to certain cells to repopulate the wound area to form a new attachment apparatus. Clinically this is accomplished by placing a barrier over the defect thereby excluding gingival tissues from the wound during early healing. The first generation of GTR barriers were non-resorbable which implies that they have to be removed in a second surgical procedure. Resorbable barriers have recently been introduced, changing GTR into a single-step procedure. Periodontal defects that will predictably benefit from GTR therapy are intrabony, furcation class II and gingival recession defects. This paper reviews the scientific evidence of what can be achieved by GTR procedures for various periodontal defects as well as factors of importance to increase the predictability of a successful treatment outcome.

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.