IN VITRO EVALUATION OF ROOT CANAL PREPARATION USING OSCILLATORY AND ROTARY SYSTEMS IN FLATTENED ROOT CANALS

Objective:

The aim of this study was to evaluate the biomechanical preparation of flattened root canals using the following systems: Endo-Eze AET stainless steel oscillatory instruments (Ultradent) and RaCe rotary NiTi instruments (FKG Dentaire).

Materials and Methods:

Twenty extracted human mandibular incisors were randomly assigned to two groups: Group 1 - Instrumentation with oscillatory Endo-Eze AET files (oscillatory technique); Group 2 - Instrumentation with rotary NiTi RaCe files (rotary technique). The teeth were decoronated, had their apices and coronal openingssealed with sticky wax and were embedded in crystal-clear orthophtalic polyester resin. The roots were sectioned transversally with diamond discs at 10 mm (middle third) and 5 mm (apical third) from the apex and the segments were reassembled for instrumentation. The sections were photographed before and after root canal instrumentation and evaluated with respect to whether the original root canal shape was modified by instrumentation. To evaluate the differences in the root canal shape before and after biomechanical preparation, scores were given regarding the instruments touch on the intracanal walls.

Results:

In middle third of the root canals instrumented with the rotary system, there was a change in the original canal anatomy (p<0.05), with formation of a protuberance in the mesiodistal direction. This protuberance did not occur when the oscillatory instrumentation was used. The oscillatory system had better results in the middle and apical thirds as evaluated by Dunn’s multiple-comparison test (p>0.05).

Conclusion:

Under the tested conditions, Endo-Eze oscillatory system yielded the instrumentation of all flattened root canal walls, maintaining the canal original shape throughout the biomechanical preparation, and was more effective than RaCe rotary system.     

COMPARISON OF THE CLEANING EFFICACY OF THE FKG RACE SYSTEM AND HAND INSTRUMENT IN MOLAR ROOT CANAL

Introduction and objective:

The aim of this study was to evaluate the ability of root canal cleaning of the RaCe rotary instrumentation system (FKG Dentaire – La-Cheaux-de Fonds – Switzerland), compared to manual filing with Stainless Steel K-files (Maillefer Instruments – Ballaigues – Switzerland).

Material and Method:

Twenty extracted human teeth (maxillary molars) were selected and their pulp tissue was removed after coronal access. The root canals were filled with a dye (India ink) and allowed to dry for 48 hours, followed by establishment of the working length of the mesiobuccal root; then, half of the specimens were instrumented by the modified Oregon technique and the other half were instrumented by crown-down sequence of the RaCe system. After preparation, the teeth were longitudinally sectioned and evaluated according to the amount of remaining dye.

Results:

Data obtained were registered as numerical scores, and the arithmetic means were compared between groups using the Mann Whitney test. Both techniques were unable to completely clean the interior of the root canals, with a better performance of the manual technique only at the middle third.

Conclusion:

It could be concluded that the RaCe system was able to provide satisfactory cleaning, similar to that obtained by the manual instrumentation technique.     

EVALUATION OF APICAL DEVIATION IN ROOT CANALS INSTRUMENTED WITH K3 AND ProTaper SYSTEMS

Objectives:

this study evaluated the apical deviation of curved root canals instrumented with K3 and ProTaper systems.

Material and methods:

twenty root canals of human maxillary and mandibular first molars were employed, which were divided into 2 groups: group A (10 teeth) was instrumented with the K3 system, and group B (10 teeth) with the ProTaper system. Evaluation of deviation was performed by double radiographic exposure. Radiographs were achieved before and after instrumentation, with 0.3-second, thus allowing superimposition of images. Three-dimensional computerized tomograph was performed in 3 specimens in each group, as an additional means to evaluate the apical deviation.

Results:

were evaluated by the parametric test Student-Newman-Keuls at 5%, which did not reveal significance between groups concerning the apical deviation. The results of computerized tomograph images demonstrated that the larger deviation of the root canal occurred at the distolingual area for both systems.

Conclusions:

both techniques produced a mild apical deviation. Computerized microtomography was shown to be accurate for experimental endodontics studies.     

IN VIVO EVALUATION OF THE SEALING ABILITY OF TWO ENDODONTIC SEALERS IN ROOT CANALS EXPOSED TO THE ORAL ENVIRONMENT FOR 45 AND 90 DAYS

This in vivo study evaluated the sealing ability of a resin-based sealer (AH Plus) and a zinc oxide-eugenol sealer (Endofill) in dogs'' teeth, exposed to the oral environment for 45 and 90 days. Forty eight lower incisors from 8 dogs were endodonticaly treated. A stratified randomization determined the sealer use in each root canal. All canals were filled using the lateral condensation technique. The excess filling material at the cervical portion of the root canal was sectioned, leaving a 10-mm obturation length inside the canal. Teeth were provisionally sealed with glass ionomer cement for 24 h and the canals were exposed to the oral environment for either 45 or 90 days. Therefore, the experimental groups were as follows: A45- AH Plus for 45 days; A90- AH Plus for 90 days; E45- Endofill for 45 days; and E90- Endofill for 90 days (n=12). After the experimental period, the dogs were killed and the lower jaw was removed. The incisors were extracted and the roots were covered with two coats of nail varnish. The teeth were immersed in India ink for 96 h and submitted to diaphanization. Dye leakage (in mm) was measured using stereomicroscopy (10x magnification). The results were statistically analyzed using two-way ANOVA and Tukey test for multiple comparisons (á = 0.05). Group E90 (2.03±0.94) showed significantly higher mean leakage value than all other groups (p<0.001). None of the sealers, in both study conditions, were able to prevent dye leakage.     

EVALUATION OF THE THERMOPLASTICITY OF DIFFERENT GUTTA-PERCHA CONES AND THE TC SYSTEM

Objective:

The aim of this study was to evaluate the thermoplasticity of three commercial brands of gutta-percha (Tanari, Dentsply 0.06, and Roeko), and of the TC system.

Materials and Methods:

Standardized specimens were fabricated from the materials to be evaluated. Specimens were placed in water at 70°C for 60 seconds. Following that, they were positioned between two glass slabs and each set was compressed by a 5kg weight. Images of the specimens before and after compression were digitized and analyzed by the Image Tool software. The flow capacity of each material was confirmed by the difference between the initial and final areas of each sample.

Results:

The resulting data were analyzed by ANOVA. The TC system presented the greatest thermoplasticity values (p<0.05). Among the gutta-percha cones, the Roeko brand showed higher thermoplasticity than the others (p<0.05).

Conclusion:

The gutta-percha from TC system present good thermoplasticity capacity.     

EVALUATION OF THE BIOCOMPATIBILITY OF ROOT CANAL SEALERS USING SUBCUTANEOUS IMPLANTS

The purpose of this study was to evaluate in vivo the biocompatibility of Endométhasone, Pulp Canal Sealer EWT and AH-Plus root canal sealers after implantation in rat connective tissue. Twenty-four Wistar-Furth rats were used. Polyethylene tubes were filled with the sealers and implanted into specific dorsal subdermal tissue sites of the rats. Implants were removed after 3, 7 and 30 days, fixed and processed for glycol methacrylate-embedding technique to be examined microscopically. On the 3rd day, there was a mild inflammatory reaction to Pulp Canal Sealer EWT implants, but a severe response to the other sealers with presence of acute inflammatory cells. On the 7th day, tissue organization was more evident with attenuation of the inflammatory reaction, especially for the AH-Plus implants. On the 30th day, connective tissue with few inflammatory cells was observed in contact with all sealer implants. In this time interval, the tissue in contact with Pulp Canal Sealer EWT implants was more organized, while the tissue close to Endométhasone and AH-Plus implants showed a mild persistent inflammatory reaction and had similar results to each other. In conclusion, the sealers had a similar pattern of irritation, which was more severe in the beginning and milder with time, in such a way that all sealers showed a persistent mild reaction. Pulp Canal Sealer EWT yielded better tissue organization than Endométhasone and AH-Plus, which, in turn, showed similar results to each other.     

CLEANING ABILITY OF CHLORHEXIDINE GEL AND SODIUM HYPOCHLORITE ASSOCIATED OR NOT WITH EDTA AS ROOT CANAL IRRIGANTS: A SCANNING ELECTRON MICROSCOPY STUDY

The aim of this study was to evaluate the cleaning efficacy of 2% chlorhexidine gluconate gel (CHX) compared to 2.5% sodium hypochlorite solution (NaOCl) associated or not with 17% EDTA used as irrigants during the biomechanical preparation. Fifty freshly extracted single-rooted human teeth with complete apex formation were randomly divided into five groups: G1 - sterile saline, G2 - 2.5% NaOCl, G3 - 2% CHX, G4 - 2.5% NaOCl + EDTA and G5 - 2% CHX + EDTA. The specimens of G1 were subdivided into two control groups. The teeth were decoronated and the coronal and middle root thirds were prepared with Gates-Glidden burs, and the apical third was reserved to manual instrumentation. All procedures were performed by a single operator. In all groups, 2 mL of irrigant was delivered between each file change. The teeth were sectioned and prepared for analyses under scanning electron microscopy (SEM). SEM micrographs were graded according to a score scale by two examiners. Data were analyzed statistically by Kruskal-Wallis and Dunn tests at 1% significance level. The best results were obtained in the groups in which the irrigant was used followed by the chelating agent. No statistically significant difference was observed among G4, G5 and the positive control group (p<0.01). The groups G2 and G3 were significantly different from the others, presenting the worst cleaning capacity. In conclusion, the use of the chelating agent is necessary to obtain clean canal walls, with open tubules and no heavy debris. The use of 2% chlorhexidine gluconate gel alone is not able to remove the smear layer.     

INFLUENCE OF SMEAR LAYER REMOVAL ON THE OBTURATION OF ROOT CANAL RAMIFICATIONS

Objective:

This study evaluated whether smear layer removal has any influence on the filling of the root canal system, by examining the obturation of lateral canals, secondary canals and apical deltas.

Material and Methods:

Eighty maxillary and mandibular canines were randomly divided into two groups, according to their irrigation regimen. Both groups were irrigated with 1% NaOCl during canal shaping, but only the teeth in Group II received a final irrigation with 17% EDTA for smear layer removal. The root canals were obturated with lateral condensation of gutta-percha and the specimens were cleared, allowing for observation under the microscope.

Results:

In Groups I and II, 42.5% and 37.5% of the teeth, respectively, presented at least one filled canal ramification. Although a larger number of obturated ramifications was found in Group I, there were no statistically significant differences between the two groups (p = 0.4957).

Conclusion:

Smear layer removal under the conditions tested in this study did not affect the obturation of root canal ramifications when lateral condensation of gutta-percha was the technique used for root canal filling.     

IN VITRO STUDY OF THE EFFECT OF ER:YAG LASER IRRADIATION ON THE APICAL SEALING OF DIFFERENT ROOT CANAL SEALERS

Objectives:

The aim of this study was to determine the effect of Er:YAG laser irradiation used to clean dentinal walls on the apical sealing of root canals filled with different types of sealers.

Background Data:

Laser application to the dentinal walls removed debris, rendering the root canals free of smear layers and leaving the dentinal canaliculi open.

Methods:

Sixty-four maxillary canines obtained from laboratory files were instrumented with K-files (Dentsply, Maillefer, Ballaigues, Switzerland) using the crown-down technique, and irrigated with a 0.5% sodium hypochlorite solution. The specimens were divided into two groups of 32 teeth each. In group I, the teeth were instrumented and irrigated with sodium hypochlorite solution, and divided into four subgroups to be sealed with the different materials (Endofill, N-Rickert, Sealapex and Sealer 26). In group II, the root canals were subjected to Er:YAG laser irradiation (200 mJ, 7 Hz and 60 J total energy), followed by root canal sealing as in group I.

Results:

The data showed lower levels of apical microleakage in the teeth filled with N-Rickert, Sealapex and Sealer 26 cements than in those sealed with Endofill (p < 0.01). No significant difference in microleakage was observed between teeth irrigated only with 0.5% sodium hypochlorite and those submitted to Er:YAG laser application (p > 0.05).

Conclusions:

The Er:YAG laser irradiation applied to the root canal walls was not able to prevent apical microleakage.     

A SCANNING ELECTRON MICROSCOPIC STUDY OF HYPERCEMENTOSIS

The purpose of this study was to evaluate morphological characteristics of teeth with hypercementosis that are relevant to endodontic practice. Twenty-eight extracted teeth with hypercementosis had their root apexes analyzed by scanning electron microscopy (SEM). The teeth were divided according to tooth groups and type of hypercementosis. The following aspects were examined under SEM: the contour and regularity of the root surface; presence of resorption; presence and number of apical foramina, and the diameter of the main foramen. The progression of club shape hypercementosis was directly associated with the presence of foramina and apical foramen obstruction. Cases of focal hypercementosis presented foramina on the surface, even when sidelong located in the root. Circular cementum hyperplasia form was present in 2 out of 3 residual roots, which was the highest proportion among the tooth types. The detection of a large number of foramina in the apical third of teeth with hypercementosis or even the possible existence of apical foramen obliteration contributes to understand the difficulties faced during endodontic treatment of these cases.     

MORPHOLOGIC AND MORPHOMETRIC ANALYSIS OF THE ROOT CANAL APICAL THIRD CLEANING AFTER BIOMECHANICAL PREPARATION USING 3.3% RICINUS COMMUNIS DETERGENT AND 1% NaOCL AS IRRIGATING SOLUTIONS

This study evaluated, by morphologic and morphometric analyses, the cleaning of apical third of root canals instrumented with nickel-titanium rotary files using different irrigating solutions. Twenty-seven single-rooted mandibular premolars were assigned to three groups (n=9), according to the irrigating solution used: Group I, distilled and deionized water; Group II, 1% NaOCl; and Group III, 3.3% Ricinus communis detergent. Biomechanical preparation was performed with Protaper Plusâ nickel-titanium files as follows: S1, SX and S2 at the cervical and middle thirds, and 25/02, 25/04, 25/06, 30/02, 30/04 and 30/06 to complete the instrumentation, operating at 1 mm from the root apex. Irrigation was done at each file change with 2 mL of irrigating solution, totalizing 20 mL for each tooth. After biomechanical preparation, the apical thirds were serially sectioned and histologically processed. The cross-sections were examined by an optical microscope (X40) connected to a computer. The images were captured and analyzed using a computer software and submitted to morphometric analysis with aid of a grid. The percentage of debris remaining at the apical third was calculated. Data were submitted to statistical analysis by ANOVA and Tukey test. The results showed no statistically significant difference (p>0.01) between the groups irrigated with 1% NaOCl and 3.3% Ricinus communis detergent, which presented the lowest percentage of debris at the apical third, 8.49% and 10.11%, respectively. The group irrigated with distilled and deionized water had the highest percentage of debris (15.58%) and was statistically different from the other groups (p<0.01). It may be concluded that 3.3% Ricinus communis detergent and 1% NaOCl had similar cleaning effectiveness on removal of debris from root canals.     

HISTOLOGICAL ANALYSIS OF THE BIOCOMPATIBILITY OF THREE DIFFERENT CALCIUM HYDROXIDE-BASED ROOT CANAL SEALERS

Objective:

To histologically evaluate the behavior of the subcutaneous tissue of rats after placement of polyethylene tubes filled with calcium hydroxide-based root canal sealers (Sealapex™, Apexit™ e Sealer 26™).

Study design:

The study employed 60 rats, which were divided into eight groups, being four experimental groups with 10 rats each, and four control groups with five rats. Analysis was conducted at 48 hours, 7, 21 and 60 days. Results: Histological analysis revealed that all sealers were irritant; however, the intensity varied between each sealer and as a function of time. At the initial periods (48 hours and seven days), all materials demonstrated similar outcomes, with inflammatory reaction from severe to moderate, respectively. At the final periods (21 and 60 days), the tissue reactions to the implants containing Sealapex™ displayed an active status yet with regression, compared to the Apexit™ and Sealer 26™. The control groups exhibited less inflammatory cells than the experimental groups, keeping a reaction status with regression.

Conclusions:

The results achieved in this study revealed that the Sealapex™ sealer was the most compatible, followed by Apexit™ and Sealer 26™     

HISTOMICROBIOLOGIC ASPECTS OF THE ROOT CANAL SYSTEM AND PERIAPICAL LESIONS IN DOGS' TEETH AFTER ROTARY INSTRUMENTATION AND INTRACANAL DRESSING WITH Ca(OH)2 PASTES

OBJECTIVE:

The purpose of this study was to evaluate the distribution of microorganisms in the root canal system (RCS) and periapical lesions of dogs'' teeth after rotary instrumentation and placement of different calcium hydroxide [Ca(OHy-based intracanal dressings.

MATERIALS AND METHODS:

Chronic periapical lesions were experimentally induced in 80 premolar roots of four dogs. Instrumentation was undertaken using the ProFile rotary system and irrigation with 5.25% sodium hypochlorite. The following Ca(OH)₂-based pastes were applied for 21 days: group 1 - Calen (n=18); group 2 - Calen+CPMC (n=20); group 3 - Ca(OH₂ p.a. + anaesthetic solution (n=16) and group 4 - Ca(OH₂ p.a.+ 2% chlorhexidine digluconate (n=18). Eight root canals without endodontic treatment constituted the control group. Histological sections were obtained and stained with Brown & Brenn staining technique to evaluate the presence of microorganisms in the main root canal, ramifications of the apical delta and secondary canals, apical cementoplasts, dentinal tubules, areas of cemental resorption and periapical lesions. The results were analyzed statistically by the Mann-Whitney U test (p<0.05).

RESULTS:

The control group showed the highest prevalence of microorganisms in all sites evaluated. Gram-positive cocci, bacilli and filaments were the most frequent morphotypes. Similar microbial distribution patterns in the RCS and areas of cementum resorption were observed in all groups (p>0.05). The percentage of RCS sites containing microorganisms in groups 1, 2, 3, 4 and control were: 67.6%, 62.5%, 78.2%, 62.0% and 87.6%, respectively.

CONCLUSION:

In conclusion, the histomicrobiological analysis showed that the rotary instrumentation and the different calcium hydroxide pastes employed did not effectively eliminate the infection from the RCS and periapical lesions. However, several bacteria seen in the histological sections were probably dead or were inactivated by the biomechanical preparation and calcium hydroxide-based intracanal dressing.     

EVALUATION OF THE APICAL INFILTRATION AFTER ROOT CANAL DISRUPTION AND OBTURATION

The aim of this study was to evaluate two root canal filling techniques used in teeth that had their apical foramen disrupted and compare the apical infiltration with an ideal clinical situation. Twenty-seven freshly extracted single-rooted teeth were selected and radiographed to confirm the existence of a single and straight root canal. The crowns were removed at a mean distance of 11 mm from the apex. The teeth had the root canals instrumented and were randomly assigned to 3 groups (n=9): ND group - root canals were filled using the lateral compaction technique and no disruption was performed; DRF group - the apical constriction was disrupted by advancing a #40 K-file 1 mm beyond the original working length, the canals were reinstrumented to create an apical ledge at 1 mm from the apical foramen and were obturated with a master gutta-percha cone with same size as the last file used for reinstrumentation; DF group - the teeth had the apical constriction disrupted and the canals were obturated with a master gutta-percha cone that fit at 1 mm from the apex. The teeth were submitted to dye leakage test with Rhodamine B for 7 days, using vaccum on the initial 5 min. The teeth were sectioned longitudinally and the leakage was measured in a linear fashion from apex to crown. There was no statistically significant difference (p>0.05) between the groups that had the apical foramen disrupted (DF, DRF), but significant difference was found between the disrupted groups and the non-disrupted one (p<0.01). In conclusion, none of the evaluated techniques was able to prevent apical infiltration, so working length so the working length determination has to be established and maintained carefully.     

EFFECT OF IMMEDIATE AND DELAYED POST SPACE PREPARATION ON THE APICAL SEAL OF ROOT CANALS OBTURATED WITH DIFFERENT SEALERS AND TECHNIQUES

During mechanical preparation of the post space, the root canal filling may be twisted or vibrated, depending on several factors associated with the preparation technique and quality of filling.

Objective:

The purpose of this study was to investigate the effect of immediate and delayed post space preparation on the integrity of the apical seal.

Material and Methods:

Sixty-four extracted human incisors were biomechanically prepared using the step-back technique. Sixty roots were randomly assigned to 6 experimental groups of 10 teeth each and the remaining 4 roots served as positive and negative controls (n=2). The root canals in the different groups were obturated with cold lateral and warm vertical condensation of gutta-percha and one of two sealers (Sealapex and Diaket). Post space was prepared either individually or simultaneously. An insulated copper wire was cut into 10-cm-long pieces. In each canal, one piece was inserted to maintain contact with gutta-percha and extended to the outside as one of two working electrodes. A stainless steel wire with the same dimensions of those of the copper wire, used as the other working electrode, was immersed into the background electrolyte from the center of the bottle. The electrical current between standard and experimental electrodes in canals was measured over a period of 10 days applying a conductivity meter. The Kruskal-Wallis test (p=0.05) determined whether there was a significant difference in microleakage among the groups and the Mann-Whitney U test (p=0.01) was used for multiple comparison grouping variables.

Results:

The results suggest that only the differences between the root canal filling techniques were statistically significant (p<0.01). There were no statistically significant difference in the sealers and the times of filling removal for post space preparation (p>0.01).

Conclusion:

The quality of the root canal filling is important for the integrity of the apical seal.     

ADHESION OF AN ENDODONTIC SEALER TO DENTIN AND GUTTA-PERCHA: SHEAR AND PUSH-OUT BOND STRENGTH MEASUREMENTS AND SEM ANALYSIS

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and guttapercha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student''s t-test (α=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to guttapercha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.     

MICROBIAL LEAKAGE AND APICAL INFLAMMATORY RESPONSE IN DOG’S TEETH AFTER ROOT CANAL FILLING WITH DIFFERENT SEALERS,POST SPACE PREPARATION AND EXPOSURE TO THE ORAL ENVIRONMENT

Coronal leakage is an important factor affecting the outcome of endodontic therapy. This study evaluated the microbial leakage (ML) and the apical inflammatory response (AIR) in dog’s teeth after root canal filling with three endodontic sealers, post preparation and exposure to the oral environment, testing the hypothesis that there is a positive correlation between these two histological parameters (ML and AIR). Sixty-four root canals of 8 mongrel dogs were cleaned, shaped and randomly distributed into groups according to the sealer to be used: Sealer 26 (n=18); AH Plus (n=18); RoekoSeal (n=19); no sealer – control group (n=9). Root canals were filled by the lateral condensation technique. Post space preparation left 4 mm of filling material in the apical root third, and specimens were exposed to the oral environment for 90 days. The dogs were killed and jaw blocks were histologically processed using Brown & Brenn and HE staining techniques. ML and AIR were scored from 1 to 4. Results were analyzed statistically using ANOVA, Duncan’s post-hoc test and Spearman’s correlation. ML and AIR score means were: Sealer 26 - 2.44±0.98 and 2.50±0.70; AH Plus - 2.50±0.78 and 2.22±0.54; RoekoSeal - 1.84±0.95 and 2.63±0.83; Control - 2.56±1.23 and 3.11±0.60. Statistically significant differences in AIR scores were found between the AH Plus and control groups (p<0.05). Although RoekoSeal had the lowest ML means, and AH Plus, the lowest AIR means after 90-day exposure to the oral environment, no statistically significant differences were found between the three sealers under study, and no correlation was found between ML and AIR.     

The restoration of permanent immature anterior teeth,root filled using MTA: A review

Objectives

Immature anterior teeth are at high risk of root fracture following root canal treatment. The literature was explored to determine the current status for post-endodontic restorative management of these teeth.

Data and sources

The authors explored multiple search engine databases to November 2008. Experiments included in the review involved simulated human or animal immature teeth with mineral trioxide aggregate as an apical plug. The experiments were designed to assess and compare the fracture strength of teeth restored with various materials. Studies that did not fulfil inclusion criteria were omitted from the review.

Study selection

Four in vitro studies fulfilled selection criteria and were systematically reviewed. All studies differed in sources of teeth, their simulated immature tooth model and mode of force application.

Clinical Implications

Current evidence, mostly from laboratory studies, suggests the use of composite resin materials placed deep into the coronal aspect of the root canal to impart superior fracture resistance. Further clinical research is needed to assess other reinforcing materials, which include a variety of post systems and luting agents.     

MORPHOMETRIC AND MICROSCOPIC EVALUATION OF THE EFFECT OF GALLIUM NITRATE AS A ROOT CANAL DRESSING IN RAT TEETH SUBMITTED TO LATE REPLANTATION

The purpose of this study was to test a gallium nitrate solution, a resorption inhibitor, employed as a root canal dressing in teeth submitted to late replantation. Thirty maxillary right central incisors of rats were avulsed and kept dry for thirty minutes. The teeth were instrumented and the root surfaces were treated with 1% hypochlorite solution followed by application of 2% sodium fluoride. Thereafter, the teeth were divided into two groups according to the root canal dressing: Group I, solution of gallium nitrate; and Group II, calcium hydroxide paste. The teeth were then replanted in their respective sockets. The animals were killed at 15, 30 and 60 days after replantation and the samples were processed for morphometric and microscopic analysis. The results demonstrated that the gallium nitrate solution and the calcium hydroxide paste limited the root resorption, yet they did not impair its occurrence. It may be concluded that gallium nitrate solution and calcium hydroxide paste demonstrated similar performance.     

RADIOGRAPHIC STUDY OF THE PREVALENCE OF APICAL PERIODONTITIS AND ENDODONTIC TREATMENT IN THE ADULT POPULATION OF S?O LUíS,MA, BRAZIL

This study investigated the prevalence of apical periodontitis (AP) and its association with endodontically treated teeth in residents of São Luís, MA, Brazil. Two-hundred complete series of periapical radiographs taken over a 10-year period (1993-2003) were retrieved from the files of four prosthesists and five periodontists. The Periapical Index (PAI) was used and the age range, sex, tooth groups, location and association with endodontic treatment (ET) were also analyzed. The Cohen Kappa and Chi-square tests were used for statistical analysis. Out of 200 patients, 135 presented at least one case of AP, which corresponds to a prevalence of 67.5%. Of the 5008 teeth examined, 296 had AP and 553 had ET. Therefore, considering the total number of teeth, AP and ET prevalences were 5.9% and 11%, respectively. Of the 553 endodontically treated teeth, 235 (42.5%) were associated with AP. Chi-square test showed a strong correlation between AP and ET (p<0.05). The 40-year-old age group was significantly the most prevalent (p<0.05). There was no association between AP and patient''s sex (p>0.05). The maxillary incisors were the most affected group of teeth (p<0.05). AP had predilection for the maxilla and was strongly associated with endodontically treated teeth (p<0.05). The prevalence of apical periodontitis and endodontically treated teeth with AP was high and similar to the results of studies performed in other countries.