In vitro effects of citric acid application techniques on dentin surfaces

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.

Root surface modifiers and subepithelial connective tissue graft for treatment of gingival recessions: a systematic review

BACKGROUND AND OBJECTIVE

Many techniques and flap designs have been used to treat gingival recession by root coverage, but subepithelial connective tissue graft (SCTG) seems to be the gold standard procedure. In an attempt to improve the healing process and increase the success rate of root coverage, some authors have used root modifiers, including different root conditioners, lasers, EMD, recombinant human growth factors and platelet-rich plasma (PRP). The aim of this systematic review was to evaluate the effects of root biomodification in clinical outcomes of gingival recessions treated with SCTG.

MATERIAL AND METHODS

Studies reporting SCTG associated with any form of root surface biomodification for root coverage of gingival recessions (Miller Class I and Class II) were considered as eligible for inclusion. Studies needed to have data of clinical outcomes in a follow up of at least 6 months. Screening of the articles, data extraction and quality assessment were conducted independently and in duplicate.

RESULTS

None of the products evaluated (citric acid, EDTA, PRP, lasers and EMD) showed evident benefits in clinical outcomes. Test and control groups presented similar outcomes related to root coverage and periodontal parameters, with no statistical differences between them. The exception was root biomodification with the neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, which impaired root coverage and had a detrimental effect on clinical outcomes.

CONCLUSION

Based on the present clinical data, the use of root surface modifiers to improve clinical outcomes in gingival recessions treated with SCTG is not justified. More in vivo studies, and randomized clinical trials with larger sample sizes and extended follow up, are necessary.

Effect of citric acid, tetracycline, and doxycycline on instrumented periodontally involved root surfaces: A SEM study

BACKGROUND

A surface smear layer consisting of organic and inorganic material is formed on the root surface following mechanical instrumentation and may inhibit the formation of new connective tissue attachment to the root surface. Modification of the tooth surface by root conditioning has resulted in improved connective tissue attachment and has advanced the goal of reconstructive periodontal treatment.

AIM

The aim of this study was to compare the effects of citric acid, tetracycline, and doxycycline on the instrumented periodontally involved root surfaces in vitro using a scanning electron microscope.

SETTINGS AND DESIGN

A total of 45 dentin samples obtained from 15 extracted, scaled, and root planed teeth were divided into three groups.

MATERIALS AND METHODS

The root conditioning agents were applied with cotton pellets using the Passive burnishing technique for 5 minutes. The samples were then examined by the scanning electron microscope.

STATISTICAL ANALYSIS USED

The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows). For all quantitative variables means and standard deviations were calculated and compared. For more than two groups ANOVA was applied. For multiple comparisons post hoc tests with Bonferroni correction was used.

RESULTS

Upon statistical analysis the root conditioning agents used in this study were found to be effective in removing the smear layer, uncovering and widening the dentin tubules and unmasking the dentin collagen matrix.

CONCLUSION

Tetracycline HCl was found to be the best root conditioner among the three agents used.

Effects of citric acid and EDTA on periodontally involved root surfaces: a SEM study

AIM

Root debridement by scaling and root planing may not completely remove contaminated cementum particularly in more apical areas. The smear layer formed during root planing inhibits cell migration and attachment leading to impaired marginal periodontal healing. The present study was done to compare the morphological effects of root surface demineralization using citric acid and EDTA as root-conditioning agents.

MATERIALS AND METHODS

Thirty fragments of human dental roots previously exposed to periodontal disease were scaled and randomly divided into the following groups of treatment: Group I: Hand instrumentation and conditioning with normal saline for 5 minutes as control; group II: Hand instrumentation and conditioning with citric acid (pH 1) for 5 minutes and group III: Hand instrumentation and conditioning with EDTA (pH-7.4) for 5 minutes. 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

The mean efficacy of smear layer removal was compared between groups I and II, groups I and III and groups II and III, it was found to be statistically significant at 5%. When the mean diameter of the dentinal tubules and mean total surface area occupied by the dentinal tubule orifices was compared between groups II and III it was found to be statistically significant at 1% level of significance.

CONCLUSION

Citric acid causes greater degree of morphological alterations than EDTA and is considered to be a better root-conditioning agent. However, the use of EDTA cannot be ruled out.

CLINICAL SIGNIFICANCE

This study supports the hypothesis that demineralizing agents can be used as an adjunct to the periodontal treatment aiming at restoring the biocompatibility of roots and helps in choosing an appropriate agent for root conditioning.

The effect of lathyrism on dentin structure of the rat incisors: a morphometric and scanning electron microscopic investigation

BACKGROUND

The present study was designed to study the effect of beta-aminopropionitrile (beta-APN), present in Lathyrus sativus grass pea consumed in drought prone areas, on dentin of the continuously erupting rat incisors.

METHODS

Eighteen adult male rats were used. In the experimental group (18 rats), lathyrism was induced by a once daily subcutaneous administration of beta-APN for 40 days. The maxillary and mandibular incisors were examined ultrastructurally and morphometrically.

RESULTS

The mean number of patent tubules, the mean area, perimeter and the area percent of the tubules were analyzed. Ultrastructurally, the dentinal tubules of both coronal and radicular dentin in the lathyritic group were narrower or even obliterated compared with those in the control. The coronal and radicular dentin of the lathyritic group exhibited an irregular lattice of non-mineralized small branching collagen fibrils obliterating the dentinal tubules. The mean number of patent tubules in the control and lathyritic groups revealed an insignificant difference. The mean area of the tubules showed a statistically significant difference in lathyritic radicular dentin (P = 0.0353). The percentage of the total surface area of the dentinal tubules significantly decreased in the radicular dentin of the lathyritic group (P = 0.024).

CONCLUSIONS

These findings indicated a deleterious effect of lathyrism on dentin, with a possible negative impact on developing teeth integrity.

Comparitive effects of tetracyclines and citric acid on dentin root surface of periodontally involved human teeth: A scanning electron microscope study

Periodontal diseases produce physical and chemical alterations in the root cementum. Various topical applications as root conditioning agents have been recommended as an adjunct to mechanical root surface debridement to remove smear layer, endotoxins and to expose collagen fibers on dentin surface. The objectives were to compare dentin surface changes following applications of tetracyclines and citric acid to the instrumented root surface of periodontally involved human teeth under scanning electron microscope.The study group comprised of 80 dentin samples, which were prepared from periodontally-compromised teeth, planned for extraction. Diseased surfaces were root planed. The teeth were sectioned and solutions of tetracycline HCl, minocycline, doxycycline and citric acid were applied to the surfaces with cotton pellets for 5minutes.The root surface samples were then examined by scanning electron microscope.Removal of smear layer in all the four groups was near total except a few areas. All four groups showed slight difference in mean number of total dentinal tubules. Minocycline and doxycycline showed no significant difference. The proportion of patent dentinal tubules was (74%) in tetracycline HCl group compared to minocycline (48.3%), doxycycline 42%), citric acid (52%), showing the differences statistically significant. Tetracycline group showed higher number of patent tubules when compared to minocycline, doxycycline and the difference was statistically significant.Results of this study suggest that tetracycline is the best current tetracycline form for root surface conditioning as measured by its ability to affect both dentin smear layer removal and tubule exposure.

A new method for quantitative analysis of dentinal tubules

Conventional methods to estimate the number of dentinal tubules cannot be considered reliable and repeatable, because results depends on the operator outlining of the tubules contours. In this study, we propose a totally automated computerized analysis technique to evaluate dentinal tubules and their surface area. The comparison test of these conventional with a semi-automatic methods shows that the automated analysis allowed a reliable identification and numbering of dentinal tubules, by means of high-quality images. No statistically significant difference exists in the number of tubules and the total tubule surface area between the control and test groups.

Effects of citric acid and EDTA conditioning on exposed root dentin: An immunohistochemical analysis of collagen and proteoglycans

OBJECTIVE

Preservation of structural and biochemical properties of the root dentin matrix is crucial to favor healing and regenerative periodontal processes. Aim of this study was to evaluate the biochemical characteristics of collagen and chondroitin sulphate of root dentin surfaces exposed by periodontal disease after acid conditioning by means of an immunohistochemical technique.

DESIGN

Human teeth scheduled for extraction due to periodontal reason were submitted to: (A) scaling and root planning; (B) ultrasonic instrumentation; (C) no instrumentation. Teeth were then exposed to: (1) 10% citric acid; (2) 17% EDTA; (3) no etching. A double immunolabeling technique was performed to identify type-I collagen and proteoglycans and analyzed under FEI-SEM.

RESULTS

Use of 10% citric acid revealed intense labeling for collagen fibrils and proteoglycans; lower labeling was found after EDTA conditioning. Unetched specimens showed residual smear layer on the dentin surface resulting in no evident surface labeling.

CONCLUSIONS

This study supports the hypothesis that manual or ultrasonic instrumentation alone is not able to expose the sound dentin matrix, whereas a subsequent acidic conditioning exposes collagen fibrils and associated proteoglycans. The immunohistochemical technique revealed that despite their acidity, both citric acid and EDTA were able to preserve the structural and biochemical properties of the exposed dentin matrix.

Fibrin clot adhesion to dentin conditioned with protein constructs: an in vitro proof-of-principle study

OBJECTIVES

Periodontal regeneration is contingent on the adsorption, uninterrupted adhesion, and maturation of a fibrin clot to a periodontally compromised root surface. Clot adhesion appears vitally dependent on the formation of a resilient union between the clot and the root surface. Root surface demineralization will remove a root surface smear layer exposing dentin tubules and collagen matrix for enhanced clot adhesion. Recently, protein constructs have been introduced to condition the root during periodontal surgery. The effect of such root conditioning on clot adhesion has not been clarified. The objective of this study was to evaluate clot adhesion to protein conditioned dentin surfaces.

METHODS

Human dentin blocks (4 x 6 x 1 mm) were exposed to a saturated citric acid solution (CA) or a commercial ethylenediaminetetraacetic acid (EDTA) preparation using standardized protocols. Some dentin blocks were additionally conditioned with proteins, either bovine serum albumin (BSA) or an enamel matrix protein preparation (EMP). Fresh human whole blood was applied to the blocks. The blood was allowed to clot for 20 min. in a humidified chamber. The dentin blocks were rinsed 3 x 5 min. in phosphate-buffered saline under standardized conditions to test clot adhesion. They were then processed for scanning electron microscopy (SEM). Two masked examiners independently evaluated the SEM images.

RESULTS

CA removed the dentin smear layer, exposing dentin tubules and collagen. EDTA appeared less efficacious leaving smear layer residues. The BSA or EMP application resulted in a surface morphology similar to that of a smear layer. Fibrin clot adhesion was best supported by the CA-treated dentin surface. Forces produced by the rinse protocol partially removed the fibrin clot from EDTA-treated surfaces. BSA- or EMP-treated surfaces poorly retained the fibrin clot.

CONCLUSIONS

CA surface demineralization removes a dentin surface smear layer to promote adhesion of a fibrin clot. The EDTA gel appears less effective. Further conditioning of the dentin surface with protein constructs produces a surface morphology similar to that of the smear layer with poor fibrin clot retention.

Effect of ER:YAG and diode laser irradiation on the root surface: morphological and thermal analysis

BACKGROUND

The aim of the present study was to compare the effects of Er:YAG and diode laser treatments of the root surface on intrapulpal temperature after scaling and root planing with hand instruments.

METHODS

Fifteen extracted single-rooted teeth were scaled and root planed with hand instruments. The teeth were divided into 3 groups of 5 each and irradiated on their buccal and lingual surfaces: group A: Er:YAG laser, 2.94 microm/100 mJ/10 Hz/30 seconds; group B: diode laser, 810 nm/1.0 W/0.05 ms/30 seconds; group C: diode laser, 810 nm/1.4 W/0.05 ms/30 seconds. The temperature was monitored by means of a type T thermocouple (copper-constantan) positioned in the pulp chamber to assess pulpal temperature during and before irradiation. Afterwards, the specimens were longitudinally sectioned, and the buccal and lingual surfaces of each root were analyzed by scanning electron microscopy.

RESULTS

In the Er:YAG laser group, the thermal analysis revealed an average temperature of -2.2 +/- 1.5 degrees C, while in the diode laser groups, temperatures were 1.6 +/- 0.8 degrees C at 1.0 W and 3.3 +/- 1.0 degrees C at 1.4 W. Electronic micrographs revealed that there were no significant morphological changes, such as charring, melting, or fusion, in any group, although the specimens were found to be more irregular in the Er:YAG laser group.

CONCLUSIONS

The application of Er:YAG and diode lasers at the utilized parameters did not induce high pulpal temperatures. Root surface irregularities were more pronounced after irradiation with an Er:YAG laser than with a diode laser.

[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.

An in vitro screening model to evaluate root conditioning protocols for periodontal regenerative procedures

BACKGROUND

Preclinical studies have shown that the condition of the root surface may play a decisive role for outcome of wound healing between a mucogingival flap and a denuded root surface. Root surface demineralization has been shown to promote the establishment of a new connective tissue attachment. Conversely, root conditioning with extracellular matrix proteins or fluorides has produced outcomes characterized by a long junctional epithelium. Collectively, present evidence suggests that early events in the healing sequel; i.e., the adsorption and adhesion of blood elements to the root surface are critical for outcomes of wound healing between a mucogingival flap and a denuded root surface. Ultimately understanding and control of these events are vital for successful design and execution of periodontal regenerative protocols, particularly those involving root conditioning. Consequently, the objective of this study was to develop a screening model for immediate evaluation of the influence of root conditioning protocols on the adsorption and adhesion of blood to dentin surfaces.

METHODS

Planed and citric acid-treated human dentin surfaces were exposed to fresh blood allowed to clot and were then rinsed before scanning electron microscopy evaluation.

RESULTS

Citric acid treated planed dentin surfaces presented a thick network of fibrin directly attaching to the dentin surface entrapping cellular elements, mainly erythrocytes. In contrast, untreated, planed dentin exhibited an amorphous appearance with sparse strands of adsorbed fibrous proteins and few adherent erythrocytes.

CONCLUSIONS

This in vitro screening model may effectively distinguish dentin surfaces with potential for enhanced adsorption and adhesion of blood elements. Periodontal regenerative protocols involving root conditioning unsuccessful in maintaining the experimentally imposed fibrin clot in this model may have lesser clinical significance than those that do.

Citric acid demineralization and subepithelial connective tissue grafts

BACKGROUND

The present study was designed to evaluate the effect, if any, of citric acid root demineralization in the outcome of subepithelial connective tissue grafts performed to cover localized gingival recessions.

METHODS

Thirty-six patients participated, each providing one gingival recession; 19 received citric acid demineralization, while 17 did not. All were treated surgically with subepithelial connective tissue grafts and followed for 6 months. At baseline and 6 months, the following parameters were recorded: plaque index, gingival index, recession height, probing depth, recession width, and amount of keratinized tissue. Data were analyzed statistically to 1) evaluate the results achieved with each procedure individually over time and 2) compare the results obtained with the 2 procedures after 6 months.

RESULTS

Results showed significant reductions in recession height after 6 months independently of whether citric acid was applied or not (2.79+/-0.79 versus 2.56+/-0.73). Similarly, recession width was significantly reduced (3.74+/-1.19 versus 3.50 +/-0.73), and the width of keratinized tissue was significantly increased (2.47+/-1.6 versus 2.3+/-1.2). No significant changes in probing depth were found (-0.16+/-0.06 versus -0.13+/-0.81). No significant differences were found when both techniques were compared in any one of the parameters analyzed (all P >0.30).

CONCLUSIONS

It is concluded that: 1) the subepithelial connective tissue graft procedure provides a satisfactory solution in the treatment of localized gingival recessions, and 2) citric acid demineralization does not affect the clinical outcome of the surgical technique.

Effectiveness of 1 mol L-1 citric acid and 15% EDTA irrigation on smear layer removal

AIM

The aim of this study was to evaluate in vitro the cleansing and smear layer removal capability of alternate canal irrigation with citric acid and NaOCl.

METHODOLOGY

Eighty-one teeth were divided into three groups on the basis of the type of instrumentation, namely, manual stainless steel, Ni-Ti mechanized ProFile .04 taper or MACXim. The groups were further divided on the basis of irrigation protocol: 5% NaOCl alone, NaOCl alternated with 1 mol L-1 citric acid solution or a combination of 15% EDTA and Cetrimide solution. After longitudinal sectioning, dentinal walls were microphotographed with scanning electron microscopy at x300 and x1000 magnifications. Qualitative and quantitative cleansing level evaluations were performed using computerized image analysis software. Data were statistically evaluated using Kruskal-Wallis analysis and t-test.

RESULTS

Qualitative evaluation at x300 and x1000 showed no statistically significant differences in cleansing ability between citric acid, EDTA and NaOCl groups. Quantitative evaluation of smear layer removal, measured as open tubules/total dentinal surface ratio, showed that 1 mol L-1 citric acid solution was comparable to EDTA (11.97% vs. 10.36%) (NS); in samples treated with ProFile .04 taper instruments citric acid was most effective (16.17%), whilst in the group treated with manual instrumentation EDTA and Cetrimide were the most effective (11.94%). Specimens irrigated with 5% NaOCl demonstrated significantly more cleansing than those obtained in the other two groups (P < 0.001).

CONCLUSIONS

1 mol L-1 citric acid solution was as effective in removing smear layer as EDTA, but was superior in specimens treated with ProFile .04 taper instruments.

Comparative SEM study on the effect of different demineralization methods with tetracycline HCl on healthy root surfaces

Periodontal regeneration through the use of root demineralization received a lot of interest in periodontology. Topical application of acid to dentin surfaces produced a zone of demineralization, exposing dentin collagen fibrils and opening dentin tubules. In this study, the in vitro effects of different tetracycline HCl application techniques were investigated. According to the results of this SEM study, it may be desirable to apply tetracycline HCl using burnishing technique to expose maximum intertubular fibrils and for the tubular openings. However, this technique should be studied when placed in an in vivo system.

Citric acid demineralization of cementum and dentin: the effect of the storage medium

The purpose of this study was to see if the root surface topography of teeth, stored in saline and subsequently treated with citric acid, differred from the root surface topography of teeth that were treated immediately upon extraction, 12 freshly extracted adult human permanent teeth, with proximal surfaces free of caries and periodontal disease, were treated in succession. The crowns were removed at the level of periodontal attachment, the teeth sectioned buccal-lingually and a treatment area deligniated on each proximal section. The treatment area of 6 teeth was root planed to expose dentin (D) and scaled to remove adherent tissue and leave a cementum surfaces (C) on the other 6 teeth. A coronal-apical groove down the middle of the treatment area divided it into approximately equal parts or experimental regions. One proximal section of each tooth was placed in physiologic saline (S) and treated after 6 weeks of storage while the other proximal section was freshly treated (F). Treatment consisted of applying a 30% citric acid (CA) solution (pH = 1.60) for 5 min. Cotton pellets soaked in the citric acid solution were placed (P) on one half of the experimental area and heavily burnished (B) on the other half. Treatment areas were subsequently prepared for scanning electron microscopy analysis. Assessment was made of (i) the % of surface area tufted, (ii) fibril tufting depth (0.3) and (iii) fibril tufting density (1.3). Similarities were found in the data for both storage methods (F and S) across each application technique (P or B) and each tooth surface (D or C) with respect to the (i) % area tufted and (ii) frequency distribution of tufting depth scores. As for the application techniques, the data for burnishing was greater than placed across each storage method (F or S) and each tooth surface (D or C) for the same two parameters. The results of the study indicated that 6-week physiologic saline storage does not affect root surface demineralization by citric acid, as assessed by SEM.

Clinical evaluation of tetracycline HCl conditioning in the treatment of gingival recessions. A comparative study

Thirty Class I and Class II recessions in 30 patients were treated with a modified subepithelial connective tissue graft procedure. Fifteen recessions in the test group received a tetracycline hydrochloride (50 mg/ml) root treatment for 5 minutes (TTC-HCl group); the remaining 15 recessions composed the control group and received a citric acid root treatment for 3 minutes (CA group). Clinical assessments were taken at baseline and at 6 months. The differences between treatments were not statistically significant. In the central area of the recession, the mean percentage of root coverage was 81.7% corresponding to a mean percentage of 79.3% and 84.0% for the TTC-HCl and the CA group, respectively. In the test group, 6 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 57.8%. In the control group, 8 of the 15 recessions exhibited complete root coverage; the gingival augmentation was 43.6%. The mean surface area of root exposure was reduced from 11.53 mm2 and 13.30 mm2 to 0.34 mm2 and 0.29 mm2 for the TTC-HCl group and the CA group, respectively. This reduction corresponds to a mean percentage of 97.4% root coverage for both groups. Within the limits of this study, the results indicate that tetracycline hydrochloride and citric acid root conditioning have comparable clinical effects in root coverage surgical therapy. The data also suggest that the measurement of the surface area of the recession is a more accurate criterion in the evaluation of the mean percentage of root coverage than a single central vertical linear measurement.

Effect of tetracycline HCl on periodontally-affected human root surfaces

Scanning electron microscopy was used to evaluate surface characteristics of periodontitis-exposed instrumented human cementum and dentin surfaces following topical application of tetracycline HCl (TTC). Specimens were randomly assigned to application of sterile saline for 1 minute (control); TTC (10 mg/ml) for 1 minute and 4 minutes, respectively; and TTC (100 mg/ml) for 1 minute and 4 minutes, respectively. Solutions were applied with a cotton pellet using a burnishing technique. Control specimens exhibited an amorphous irregular surface smear layer. TTC treatment of cementum for 1 minute resulted in a relatively debris-free, nonhomogeneous surface. The 4-minute application resulted in a surface exhibiting a densely fibrillar, mat-like texture. Dentin specimens conditioned for 1 minute showed a smooth surface with many tubule openings partially occluded by debris. The 4-minute treatment exposed a 3-dimensional network of intertubular and peritubular collagen fibrils. No consistent morphologic differences were observed between cementum or dentin specimens treated with TTC at concentrations of 10 and 100 mg/ml, respectively. The results suggest that topical application of TTC produces morphologic alterations of periodontitis-exposed cementum and dentin that appear related to application interval rather than concentration of the drug.

Effects of citric acid treatment on the Ca, P and Mg contents of human dental roots

An electron microprobe analyser associated with a scanning electronic microscope was used to measure Ca, P and Mg contents of the human dental root hard tissues, before and after a citric acid treatment (pH = 1). The measurements were made on transverse sections through the cervical 1/3 of the molar roots. The measurements were performed at the following 8 levels: the internal cementum, the cementum-dentine junction, cementum-related dentine, 4 external dentine levels located at 220 microns, 420 microns, 620 microns and 820 microns from the cementum-dentine junction, and finally the juxta-pulpal dentine. After the citric acid treatment, the losses in Ca and P, but not in Mg, varied significantly with the level; an acid-resistant dentine layer of approximately 600 microns was found under the cementum-dentine junction. An increase in the Ca/P ratio was also observed in this layer. Since this external dentine zone is less demineralized by the citric acid than the underlying dentine, the collagen matrix in this region may also be less exposed. These differences in the response to citric acid that depend on the distance from the root surface may explain the unpredictability of periodontal healing after citric acid treatment of diseased root surfaces, because the amount of tissue removed during root planing is not constant.

Citric acid demineralization of cementum and dentin: the effect of application pressure

Previous work has shown that a 25-30% citric acid solution was the most effective concentration with which to demineralize dentin. The purpose of this investigation was to study the topography, using a scanning electron microscope, of root surfaces treated with a 30% citric acid solution using various application pressures. 20 freshly extracted human teeth were collected and stored in physiologic saline at room temperature. 3 root specimens, approximately 3x5x5 mm in size, were prepared from the coronal periodontally healthy area of each tooth. 30 specimens were root planed to expose dentin (dentin group) while the remaining 30 specimens were lightly scaled to remove periodontal soft tissue (cementum group). A freshly made 30% citric acid (CA) solution, (pH = 1.60), was applied to each of the experimental areas. Cotton pellets soaked in the citric acid solution were either placed (CAP), lightly rubbed (CAR) or heavily burnished (CAB) on the prepared root surface for 3 min. Pellets were resoaked every 30 s. The root sections were rinsed, fixed in glutaraldehyde, dehydrated in graded ethanol, critically point dried in liquid CO2 and sputter coated in gold. The treated surfaces were assessed for fibril tufting using scanning electron microscopy. Assessment was made of: (i) the % of surface area tufted; (ii) tufting depth (0-3); (iii) tufting density (1-3). Results of the study showed significantly more tufted surface area and greater tufting depth on both dentin and cementum for CAR and CAB compared to CAP. CAP produced a flat/mat fibril surface with no evidence of tufting.(ABSTRACT TRUNCATED AT 250 WORDS)

Root surface texture and early cell and tissue colonization after different etching modalities

The purpose of the present study was to compare the texture of dentin surfaces after etching with citric and phosphoric acids as well as EDTA with respect to mode of application and exposure time, and to assess possible effects on early cell and tissue colonization. It was concluded that EDTA operating at neutral pH was able to selectively remove mineral from a dentin surface, exposing a collagenous matrix. This was in contrast to etching with citric and phosphoric acids, both of which operate at a low pH. They both appeared to remove not only the mineral component but also the collagenous matrix. EDTA-treated dentin surfaces, compared to surfaces etched at low pH, appeared to be more inviting for cellular colonization and subsequent connective tissue formation. The reason for this may have been twofold: Dentin surfaces etched with an etching agent operating at neutral pH, as indicated above, retain more exposed collagen fibers than dentin surfaces etched at low pH. Furthermore, it can not be excluded that a low pH etching agent necrotized an area of the periodontal ligament in the immediate vicinity of the denuded dentin surfaces.

Annual review of selected dental literature: report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The annual review of selected dental literature this year cites 384 published papers and reports. This year's review contains more editorial comment than reviews of years passed. New data on the biological responses to materials is emphasized in several sections. Observations on new compounds able to prevent plaque formation are presented. Clinically relevant advances in knowledge concerning the etching of different tooth structures are reported along with the effect of etching procedures on the dental pulp. Evaluation of periodontal diseases in all age groups is a topic. Limitations of current diagnostic techniques in periodontal disease, temporomandibular disorders, and implant therapy are included. There are new views on the use of dental amalgam. The future use of dental mercury is predicted. Interest in new ceramic systems is indicated as the demand for esthetics continues. Clinical information is emphasized over scientific information throughout this year's review.