Level Of Cementoenamel Junction Research Articles

Effect of Bleaching Agents on the Sealing of Cervical Barrier in Intracoronal Bleaching Procedures

ABSTRACT Discoloration of nonvital teeth is an esthetic deficiency frequently requiring bleaching treatment. The purpose of this study was to evaluate in vitro the effect of bleaching agents on two different cervical barriers in order to minimize or prevent the leakage along the root canal filling in the intracoronal bleaching procedures. Ninety-six extracted human molars were used which were biomechanically prepared, filled and divided into eight groups. The cervical barriers tested were zinc phosphate cement (ZPC) and resin-modified glass ionomer cement (RMGIC) applied (3 mm of thickness) at the cementoenamel junction level. Forty-eight specimens were divided into four groups for each cervical barrier: (1) control group without bleaching agent, (2) a mixture of sodium perborate and distilled water, (3) a mixture of sodium perborate and 10% carbamide peroxide and (4) a mixture of sodium perborate and 35% carbamide peroxide. The bleaching agents were placed inside the pulp chamber for 7 and 14 days, and the access opening was sealed with Cimpat. After 21 days, microleakage evaluation of 2% rhodamine B dye solution at dentin-cervical barrier interface was performed by a stereomicroscope. Data were submitted to Kruskal-Wallis, Dunn's and Dunnett's tests, with a significance level of 0.05. The results demonstrated no statistically significant differences among the control group and the experimental groups for each cervical barrier (ZPC and RMGIC); there were no significant differences among the bleaching agents for the same barrier and RMGIC barrier provided better sealing than ZPC (p < 0.05). Therefore, the bleaching agents demonstrated similar performance when tested for the same cervical barrier and RMGIC barrier provided better sealing than the ZPC barrier, regardless of the association of bleaching agents used. How to cite this article Yui KCK, Huhtala MFRL, da Silva EG, Ramos CJ, Torres CRG, de Paiva Gongalves SE, Gomes APM. Effect of Bleaching Agents on the Sealing of Cervical Barrier in Intracoronal Bleaching Procedures. World J Dent 2013;4(4): 235-240.

The effects of various irrigating solutions on intra-radicular dentinal surface: An SEM analysis

Aim:The action of irrigant solutions on intra- radicular dentinal surface were evaluated in an in vitro setting using a scanning electron microscope (SEM) and it was observed that sodium hypochlorite and MTAD produced the cleanest surface and that none of the irrigants were able to produce an ideal preparation of the dentinal surface when used individually. The primary objective of endodontic therapy is to achieve a clean, optimal environment in root canals to avoid unsuccessful treatment outcomes. The complexities of the root canal system necessitate the use of irrigating solutions which act on radicular dentin surface, modifying it. The action of irrigants can be beneficial, and yet at the same time, as they modify the surface structure of dentin, they can have an adverse impact on the properties of dentin. The present study was undertaken to assess the effect of various irrigants on the dentinal surface using an SEM.Materials and Methods:Forty-five roots were randomly divided into nine groups (n=5) and prepared by sectioning at the level of cemento-enamel junction (CEJ) and 10 mm from the CEJ and split longitudinally. The dentin surface was prepared and the cemental surfaces were coated with double layer of varnish. The irrigants tested were normal saline, de-ionized water, 17% ethylenediaminetetraacetic acid (EDTA), 5% sodium hypochlorite (NaOCl), 5% NaOCl with ultrasonic agitation, 3% hydrogen peroxide, 2% chlorhexidine (CHX), MTAD, and MTAD with ultrasonic agitation. The prepared samples were placed in the irrigant solution for 3 min, subsequently dehydrated, sputter coated, and observed under SEM. The images were subsequently analyzed for dentinal surface changes.Results:17% EDTA and MTAD produced the cleanest dentinal surface. Ultrasonic agitation enhanced the effect of irrigants. 5% NaOCl and 3% hydrogen peroxide were efficient at removal of organic debris, but were unable to remove the smear layer. De-ionized water, normal saline, and 2% chlorhexidine were not effective at removing the debris or the smear layer.Conclusion:None of the irrigants individually were able to achieve conditions of an ideal dentinal surface preparation.

Platelet Rich Fibrin in the revitalization of tooth with necrotic pulp and open apex

Regeneration of pulp-dentin complex in an infected necrotic tooth with an open apex is possible if the canal is effectively disinfected. The purpose of this case report is to add a regenerative endodontic case to the existing literature about using Platelet Rich Fibrin (PRF). A nine year old boy who accidently broke his immature maxillary central incisor tooth, developed pulpal necrosis with apical periodontitis. After the access cavity preparation, the canal was effectively irrigated with 20 ml of 5.25% sodium hypochlorite solution and 10ml of 0.2% chlorhexidine solution and dried with paper points. Triple antibiotic paste was placed inside the canal and left for 21 days. 12 ml of whole blood was drawn from the patient's right antecubital vein and centrifuged for 10 minutes to obtain the Choukroun's PRF. After the removal of the triple antibiotic paste, the PRF was placed into the canal till the level of cementoenamel junction and 3mm of grey MTA was placed directly over the PRF clot. The setting of MTA was confirmed 3 days later and the tooth was double sealed with GIC and Composite restoration. After 1 year the clinical examination revealed negative responses to percussion and palpation tests. The tooth responded positively to cold and electric pulp tests. Radiographic examination revealed continued thickening of the dentinal walls, root lengthening, regression of the periapical lesion and apical closure. On the basis of the results obtained in our case report we conclude that revitalization of necrotic infected immature tooth is possible under conditions of total canal disinfection and PRF is an ideal biomaterial for pulp-dentin complex regeneration.

Age estimation of indian adults from orthopantomographs

The aim of this study was to develop a method for estimating the chronological age of Indian adults based on the relationship between age and various morphological variables of canine teeth, obtained using orthopantomographs. Orthopantomographs of 120 selected patients were digitized, and radiographic images of the right maxillary canine in each case were processed using a computer aided drafting program. Pulp/tooth area ratio, pulp/root length ratio, pulp/tooth length ratio, pulp/root width ratio at the cemento-enamel junction level, pulp/root width ratio at midroot level, and pulp/root width ratio at the midpoint between the cemento-enamel junction and the midroot of the canine were calculated by measuring various features on the images. Pearson's correlation, multiple linear regression, one way analysis of variance (ANOVA), and Student's t-test were used for statistical analysis. Regression equations were developed to estimate age from morphological variables. The observed minus the estimated age in the total study sample ranged from -2.2 to +1.5 years, in males from -0.9 to +0.8 years, while in females it was from -1 to +0.8 years. Differences between observed and estimated ages of subjects were not statistically significant. In conclusion there is a linear relationship of pulp/root width ratio at mid-root level and pulp/tooth area ratio of the right maxillary canine with chronological age in the Indian population. Age of subjects can therefore be estimated with a good degree of accuracy using regression equations.

Endodontic management of hypo‐, meso‐ and hypertaurodontism: Case reports

Taurodontism is a morpho-anatomical developmental anomaly rarely seen in teeth. It is characterised by lack of constriction at the level of cementoenamel junction with elongated pulp chambers and apical displacement of bifurcation or trifurcation of roots. This gives the tooth a rectangular or cylindrical appearance. This paper reports successful endodontic therapy of cases with hypo-, meso- and hypertaurodontism in healthy individuals with no associated syndrome or anomaly.

Revitalization of Tooth with Necrotic Pulp and Open Apex by Using Platelet-rich Plasma: A Case Report

Introduction A growing body of evidence is demonstrating the possibility for regeneration of tissues within the pulp space and continued root development in teeth with necrotic pulps and open apexes. The purpose of this case report is to add a regenerative endodontic case to the existing literature about using platelet-rich plasma (PRP). Methods An 11-year-old boy whose maxillary second premolar tooth had been accidently extracted and immediately replanted developed pulpal necrosis and symptomatic apical periodontitis. After preparing an access cavity, its necrotic pulp was removed. The canal was irrigated with 5.25% NaOCl solution and dried with paper points. A triple antibiotic mixed with distilled water was packed in the canal and left for 22 days. Twenty milliliters of whole blood was drawn from the patient’s forearm for preparation of PRP. After removal of the antibiotic mixture, the PRP was injected into the canal space up to the cementoenamel junction level. Three millimeters of grey mineral trioxide aggregate was placed directly over the PRP clot. Three days later, the tooth was double-sealed with permanent filling materials. Results Clinical examination 5 1/2 half months later revealed no sensitivity to percussion or palpation tests. Radiographic examination of this tooth showed resolution of the periapical lesion, further root development, and continued apical closure. Sensitivity tests with cold and an electric pulp test elicited a positive response similar to those found in the first premolar tooth. Conclusions On the basis of short-term results of the present case, it appears that regeneration of vital tissues in a tooth with necrotic pulp and a periapical lesion is possible; PRP is potentially an ideal scaffold for this procedure.

Management of Hypertaurodontism: An Endodontic Challenge

Taurodontism is a morpho-anatomical developmental anomaly rarely seen in teeth and usually found in association with other anomalies or as a part of syndrome. It is characterised by lack of constriction at the level of cementoenamel junction with elongated pulp chambers and apical displacement of bifurcation or trifurcation of roots. This gives the tooth a rectangular or cylindrical appearance. Endodontic treatment of a taurodont tooth is challenging, because it requires special care in handling and identifying the number of root canals. A case of endodontic treatment of a maxillary first molar with hypertaurodontism not associated with any syndrome is presented.

Microleakage comparison of glass-ionomer and white mineral trioxide aggregate used as a coronal barrier in nonvital bleaching

There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrier be used over the canal filling to prevent leakage of bleaching agents. Glass-ionomer (GI) is commonly used as a coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinity after mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluate sealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching. Root canals of one hundred thirty human maxillary incisors were instrumented and filled with gutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). The teeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups, glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following three bleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agents were 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixed with distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no coronal barrier was used. In the negative controls, all the tooth surfaces were covered by two layers of nail varnish. Microleakage was evaluated using protein leakage test. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests. The experimental groups showed minimum leakage which was not significantly more than tha in the negative controls. There was no statistically significant difference in leakage between the experimental groups (p<0.05). This study indicated that different bleaching agents have no effect on sealing ability of WMTA.

Characteristics of non-carious cervical lesions - an ex vivo study using micro computed tomography

The aetiology of non-carious cervical lesions (NCCLs) is not well understood and still controversial. The aim of this ex-vivo study was to examine the morphological characteristics of NCCLs for clinical evidence of enamel loss above the cemento-enamel junction (CEJ) as suggested by the abfraction theory. Fifty extracted human teeth with various types of NCCLs were collected and scanned by micro computed tomography. The reconstructed three-dimensional models were evaluated from multiple aspects, including longitudinal cross-section series. The location of internal line angle and proximal exits of the lesions were evaluated in relation to the level of CEJ. The coronal margins of the lesions were inspected for evidence of enamel loss above the CEJ using the bucco-lingual longitudinal sectional images. Coronal margins of the lesions were located along and/or under the CEJ for all of the 50 samples. In most of the lesions, regardless of lesion type, the proximal exits and internal line angles were located below the CEJ. This study did not detect clinical evidence of enamel loss above the occlusal margin of NCCLs as would have been expected according to the general abfraction mechanism.

Variation in SPC/STC Ratio as an Indicator of Age: A Computer-aided Forensic Odontology

Aim: The aim of the present study was to evaluate the change in pulp width at the level of cemento-enamel junction and its correlation to different age groups Materials and methods: It is a retrospective study in which we are going to see the changes in pulp width as age increases. Ground section of 100 extracted maxillary first premolars were made up to the midpulpal area in labiolingual plane. The correlation of different age group with reduction in ratio of score of pulp width (SPC ) and score of tooth width (STC ) at cemento-enamel junction was done. All teeth were examined under stereomicroscope then SPC and STC were measured by Leica Qwin software. Results: Pearson correlation between SPC/STC ratio with different age group was found to be statistically significant. So, measurement of amount of secondary dentin seems to be reliable and rapid method in forensic odontology.

“SEM evaluation of smear layer formation after using three different nickel titanium rotary instruments-endowave, K3 and protaper - An invitro study”

Background and Objectives: The purpose of this invitro study was to evaluate the smear layer formation after using three different nickel titanium rotary instruments-Endowave, K3 and Protaper using Scanning Electron Microscope. Materials and method: A total of 30 freshly extracted human mandibular premolars were subjected for the study. They were divided into 3 groups, each group consisting of 10 teeth. Group 1: Endowave rotary; Group 2: ProTaper rotary; Group 3: K3 rotary. Crowns of each tooth were removed with carborundum disks at the level of cementoenamel junction in order to obtain root segments of approximately 12mm. Canal length was determined by placing a size 15 K-file. The working length was 0.5 mm short of canal length. Two longitudinal grooves were prepared on the lingual and buccal surfaces of each root to facilitate vertical splitting with a chisel after canal instrumentation. The sections were then observed under SEM for presence or absence of smear layer and photographs were taken at coronal, middle and apical 1/3 with a magnification of 4000 X. Results: There was no significant difference between three groups. All three groups resulted in significantly more smear layer in the apical 1/3 of the canal, compared to coronal and middle 1/3. Interpretation and Conclusion: The study demonstrated that, Endowave, Protaper and K3 resulted in significantly more smear layer in the apical 1/3 of the canal, compared to coronal and middle 1/3. Cleaning was significantly more effective in the coronal and middle 1/3 of the canals

The Retention of Cast Metal Dowels Fabricated by Direct and Indirect Techniques

To explore the effect of fabrication technique, cement type, and cementation procedure on retention of cast metal dowels. Eighty intact single-rooted teeth were selected. The clinical crown was removed at the cementoenamel junction level. Each root was prepared to receive a cast metal dowel of 10-mm length and 1.45 mm in diameter. The 80 specimens were divided into two major groups of 40 based on fabrication technique (direct and indirect). Each group was further divided into four subgroups of ten based on the cement type (zinc phosphate and glass ionomer), and cementation procedure (with and without lentulo spiral). The dowels were subjected to a constantly increasing tensile force, in a universal Instron testing machine, at crosshead speed of 5 mm/min until failure. The most significant factor to affect retention was the cementation procedure, as cementation with lentulo spiral produced greater retention than cementation without the use of lentulo spiral (p < 0.05); however, there seems to be a close interaction between fabrication technique, cement type, and cementation procedure (p= 0.051). The least retentive group was the one fabricated by direct technique, cemented with zinc phosphate without the use of lentulo spiral. Fabrication technique does not affect retention of cast dowels, except when zinc phosphate was the luting agent and placed in the canal space without using a lentulo spiral. The cementation procedure had a significant effect on retention; thus, it is recommended that cementation should be done using the lentulo spiral.

Resistance to fracture of endodontically treated premolars restored with glass ionomer cement or acid etch composite resin: An in vitro study

Aim: Due to the weakness of endodontically treated posterior teeth requires more strengthened restoration to withstand occlusal forces. The purpose of the present study was to determine and compare the resistance to fracture of endodontically treated maxillary 1 st premolars restored with different materials in mesio-occluso-distal (MOD) cavity preparations. Materials and Methods: MOD cavity preparations in 80 endodontically treated maxillary 1 st premolars were restored using four different methods. Fiber rings were filled with stone plaster and the teeth were placed into the plaster up to the level of cemento-enamel junction. The teeth were grouped according to restorative method, mounted in an Instrom T.T. machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. Result: The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. All teeth fractured in a similar manner irrespective of the restorative method used. Conclusion: The resistance to the fracture of the teeth was the same when they were stored with glass ionomer cement as a base over which composite resin was placed. When the entire cavities were filled with glass ionomer cement, the resistance to fracture of the teeth decreased significantly compared with the acid etch resin technique.

Influence of smear layer on depth of penetration of three endodontic sealers: an SEM study.

The purpose of this study was to examine the effect of the smear layer on the penetration depth of Sealapex, Roth 811, and CRCS root canal sealers into the dentinal tubules. Forty recently extracted, human single-rooted teeth were used. The crowns were cut and removed at the cemento-enamel junction level and the root canals were prepared to a #60 K-file. The teeth were then randomly divided into two groups of 20, group A and group B. The smear layer was removed from all teeth in group A with EDTA and NaOCl. The smear layer remained in all teeth in group B. Two roots in each group were used as controls. Six roots from each group were obturated with Roth 811 sealer and gutta-percha through lateral condensation. The same process was repeated using sealers CRCS and Sealapex. Each root was then divided in two and prepared for scanning electron microscope observation. The removal of the smear layer allowed penetration of all three sealers into the dentinal tubules to a depth of between 35 microns and 80 microns. Although the CRCS sealer penetrated only up to the 35 mm point, it offered better or complete obturation of the dentinal tubules. The presence of smear layer at the root canal walls obstructed the penetration of all sealers into the dentinal tubules.

Morphometric analysis of the furcation anatomy of mandibular molars.

Successful treatment of molar furcation defects remains a challenge in clinical practice. Knowledge of anatomic factors facilitates predictable management of furcation involvement lesions. The degree of success in managing furcation involvement is inversely related to the horizontal probing depth. The depth of the horizontal component of attachment loss can vary depending on the external tooth-surface reference points used. However, the anatomical factors affecting horizontal component of attachment loss have not been previously assessed. Therefore, this study determined the bucco-lingual measurements of the cemento-enamel junction and the mesial and distal roots and at the level of root separation. One hundred extracted permanent human mandibular first (N = 50) and second (N = 50) molars were studied. Four horizontal bucco-lingual widths were measured with calibrated calipers: 1) furcation entrance/roof (FE); 2) cemento-enamel junction level (CEJ); 3) mesial root width (MRW); and 4) distal root width (DRW). The mean widths at FE, CEJ, MRW, and DRW were, respectively, 5.53 +/- 0.45 mm, 8.71 +/- 0.54 mm, 8.57 +/- 0.54 mm, and 7.97 +/- 0.65 mm in the first molars and 5.61 +/- 0.65 mm, 8.40 +/- 0.65 mm, 7.95 +/- 0.88 mm, and 7.16 +/- 0.84 mm in the second molars. Analysis of variance revealed significant differences between FE and the other variables tested. The results showed that the bucco-lingual width of the furcation roof is considerably shorter than the MRW and DRW. The difference in the mean bucco-lingual dimension between FE and the other measurements occurred in all teeth evaluated and varied between 0.7 and 4.30 mm. Our findings demonstrate that clinical measurements of horizontal probing depth that use the external surfaces of roots as reference points overestimate the true anatomical component of furcation involvement in mandibular molars. Conversely, positive treatment outcomes in these teeth may be underestimated. This has implications not only for clinical practice but also for clinical research studies evaluating treatment outcomes.

Assessment of root curvature and distance using computed tomography.

The safety and efficacy of subgingival root surface instrumentation may be enhanced by optimized adaptation between instrument and treated surface. Thus, detailed knowledge of root geometry may allow advances in instrument design. The aim of this study was therefore to measure root radii of various tooth types as well as distances between tooth roots using computed tomography. Two hundred sixteen teeth in eight patients were studied, with cross sections of teeth at the level of the cemento-enamel junction (CEJ) being regarded as ellipses. The maximum radii of ellipses were calculated and averaged for each tooth surface within various tooth groups. In addition, the spacing between roots at CEJ level and 5 mm below the CEJ was measured. Mean radii varied from 1.09+/-0.50 mm (lower incisor, lingual) to 13.7+/-0.96 mm (upper molar, mesial). Radii of 1 mm to 6 mm were most frequently found at buccal, palatal, and lingual surfaces, whereas the majority of radii were between 2 mm and 11 mm at mesial and distal sites. Root distance varied between 1.04+/-0.49 mm (lower incisors, CEJ level) and 2.81+/-1.70 mm (lower molars, 5 mm below CEJ). The curvature of an instrument for root surface instrumentation should correspond to a radius of at least 11 mm to achieve maximum adaptation to the treated surface, and the width of the working end should be less than 1 mm to allow sufficient interdental instrumentation.

Effect of different protective base materials on hydrogen peroxide leakage during intracoronal bleaching in vitro

External root resorption may develop following intracoronal bleaching with hydrogen peroxide. The preventive effect of different base materials on the radicular penetration of H2O2 during intracoronal bleaching was assessed. Seventy-two bovine teeth and 20 human teeth were bleached with 30% H2O2. The bovine teeth were divided into four groups and the root canals filled with either IRM, zinc oxide-eugenol, composite resin, or glass ionomer. The radicular H2O2 penetration of each group at different layer thickness was compared. The experiment with the human teeth was performed in three stages. In the first stage no protective base was used. In the second stage IRM was placed to the cementoenamel junction level. In the third stage the IRM layer was removed 0.5 mm below the cementoenamel junction. None of the materials tested in the bovine teeth showed H2O2 penetration with a base thickness of 2 mm. When the base thickness was reduced to 1 mm, several teeth showed H2O2 penetration; however, there was no significant difference among the materials tested. When the base thickness was reduced to 0.5 mm, the H2O2 penetration in each group increased. A statistical difference was found between the composite and the glass ionomer (p < 0.05). The results for the human teeth showed that IRM layer placed at the cementoenamel junction level significantly reduced the radicular H2O2 penetration as compared with teeth where the IRM was either placed 0.5 mm below the cementoenamel junction or not placed at all (p < 0.01). It is therefore recommended that a protective base be placed to the cementoenamel junction level before intracoronal bleaching to prevent possible H2O2 hazards.

X線写真による歯冠歯根比と歯槽骨破壊との関連についての研究

This study was performed to know the relationship between crown-root ratio and periodontal bone destruction.One hundred and thirty eight sets of 14-film intra-oral roentgenographs taken from patients with light and moderate periodontal disease by dental students in senior class were used.The routine paralleling long cone technique was used. Those patients were aged from 20 to 66, 73 males and 65 females.Single rooted teeth (5-5/5-5) except molars were evaluated in respect of crown-root ratio and bone destruction.These teeth were divided into groups (54, 3, 21 12, 3, 45, 54, 3, 21 12, 3, 45) and assessed independently with regard to the relationship between crown-root ratio and periodontal bone destruction.These teeth did not have metal crowns and other large restorations such as class 2, 4 or MOD inlays.The periodontal bone height was assessed by the method of Schei et al.The anatomical crown-root ratio was determined by measuring the level of cemento-enamel junction. The bone loss from the cemento-enamel junction was measured in percentage. The measuring was carried out by three trained examiners.The lowest crown-root ratio was observed in lower canine (0.44±0.06). The highest periodontal bone destruction was recognized in lower central incisor (28.4±14.0%). There was not statistically a significant correlation between crown-root ratio and periodontal bone destruction in each group.The periodontal bone destruction in different age groups was evaluated also. The periodontal bone had a tendency to be destroyed with increasing age.