Effect of root canal filling materials on dimensions of cone-beam computed tomography images

Objective

To evaluate the discrepancy of root canal filling (RCF) measurements obtained from original root specimens and cone-beam computed tomography (CBCT) images.

Material and Methods

Seventy-two human maxillary anterior teeth were prepared up to an ISO #50 K-File 1 mm short of the apical foramen. Thus, the teeth were randomly divided into 8 groups, according to the root canal filling material: Sealapex^®, Sealapex^®+gutta-percha points, Sealer 26^®, Sealer 26^®+gutta-percha points, AH PlusTM, AH PlusTM+gutta-percha points, Grossman Sealer, and Grossman Sealer+gutta-percha points. After root canal preparation and RCF, CBCT scans were acquired and the specimens were sectioned in axial, sagittal and coronal planes. The RCF measurements were obtained in different planes and thicknesses to determine the discrepancy between the original root specimens (using a digital caliper) and the CBCT images (using the scanner''s proprietary software). One-way analysis of variance and Tukey tests were used for statistical analyses. The significance level was set at α=5%.

Results

Measurements of the different endodontic filling materials were 9% to 100% greater on the CBCT images than on the original root specimens. Greater RCF dimensions were found when only sealers were used, with statistically significant difference among the groups.

Conclusions

RCF dimensions were greater on CBCT images than on the original root specimens, especially when only sealer was used.     

Effect of MTA-based sealer on the healing of periapical lesions

Some manufacturers have recently added specific components to improve the ease of handling and insertion material properties of MTA in order to create MTA-based sealers.

Objective:

The aim of this study was to evaluate the healing of periapical lesions in canine teeth after a single session of endodontic treatment with MTA Fillapex^® compared with Sealapex or Endo-CPM-Sealer^®.

Material and Methods:

Sixty-two root canals were performed on two 1-year-old male dogs. After coronal access and pulp extirpation, the canals were exposed to the oral cavity for 6 months in order to induce periapical lesions. The root canals were prepared, irrigated with a solution of 2.5% sodium hypochlorite and filled with gutta-percha and different sealers, according to the following groups: 1) Sealapex; 2) Endo-CPM-Sealer^®; and 3) MTA Fillapex. Some teeth with periapical lesions were left untreated for use as positive controls. Healthy teeth were used as negative controls. After 6 months, the animals were sacrificed and serial sections from the roots were prepared for histomorphologic analysis and stained with hematoxylin and eosin and the Brown and Brenn technique. The lesions were scored according to pre-established histomorphologic parameters and the scores statistically analyzed using the Kruskal-Wallis test.

Results:

All 3 materials produced similar patterns of healing (p>0.05); in particular, persistent inflammation and absence of complete periapical tissue healing were consistently noted.

Conclusions:

Preparation of the infected root canals followed by filling with the materials studied was insufficient to provide complete healing of the periapical tissues.     

A Comparative in Vitro Study of Apical Microleakage with Five Obturation Techniques: Lateral Condensation,Soft-Core?, Obtura II?, Guttaflow? and Resilon?

Aim

A comparison was made between the root canal lateral condensation technique and other condensation techniques in which physical (temperature: Soft-Core®, Obtura II®) or chemical changes (condensation: Guttaflow®, Resilon®) may affect the dimensional stability of obturation and thus favor apical microleakage.

Materials and methods

A total of 212 single-root teeth removed for orthodontic or periodontal reasons were randomized to 5 groups of 40 teeth each. Six samples were used as positive controls, and another 6 as negative controls. The teeth were worked with the Hero 642 system, and each group was obturated using a different technique: lateral condensation, Obtura II®, Soft-Core®, Guttaflow® or Resilon®. The samples were immersed in black ink, and after 72 hours the teeth were transparentized using the technique described by Robertson. Filtration of the ink was measured under the stereoscopic microscope. Analysis of variance and post-hoc testing were used for the statistical analysis.

Results

The Soft-Core® obturated group showed significantly greater microleakage than the other groups, with no differences among the rest of the groups.

Conclusions

Under the conditions of this study, the teeth obturated with the Soft-Core® technique showed greater apical microleakage than the other systems.Key words: Apical microleakage, root canal obturation, sealing ability, transparentization     

Effects of sulfur-based hemostatic agents and gingival retraction cords handled with latex gloves on the polymerization of polyvinyl siloxane impression materials

Objectives

This study investigated the possible interactions between three addition silicone materials (Express^®, Aquasil Ultra^® and Adsil^®), three hemostatic agents (ferric sulfate, StatGel FS^®; aluminum sulfate, GelCord^®; and aluminum chloride, Hemostop^®) and gingival retraction cords previously handled with latex gloves to determine whether direct contact with medicaments or indirect contamination by latex in conditions similar to those found in clinical practice inhibit or affect the setting of the impression materials.

Material and Methods

A portable device for the simultaneous test of several specimens was specifically developed for this study. Polymerization inhibition was analyzed by examination of the impressions and the molded surface. Ten trials were performed for each addition silicone material used in the study, at a total of 240 study samples.

Results

All the samples tested (N=240) were nonreactive regardless of the type of combination used.

Conclusions

Aluminum sulfate, ferric sulfate and aluminum chloride hemostatic solutions did not show any inhibitory potential on the addition silicone samples under study, and there were no changes in polymerization as a result of contact between addition silicone and retraction cords handled with latex gloves.     

The comparison of MTA,Geristore® and Amalgam with or without Bioglass as a matrix in sealing the furcal perforations (in vitro study)

Aim

The objective of this in vitro was to assess the sealing ability of MTA, Geristore®, and amalgam with and without Bioglass as a matrix used to repair furcation perforations in mandibular molars by using dye penetration.

Materials and methods

One hundred mandibular molars were randomly divided into six experimental groups. Five teeth with perforation were used as positive control while five teeth without perforation were used as negative control group. Furcal perforations were made in the teeth. Perforations were repaired with amalgam in group 1, amalgam and Bioglass in group 2, MTA in group 3, MTA and Bioglass in group 4, Geristore® in group 5, and Geristore® and Bioglass in group 6. All repairing materials were allowed to set for 72 h. Leakage at the repaired sites was then evaluated using dye penetration and clearing technique under stereomicroscope.

Results

The perforations repaired with MTA and Geristore® leaked significantly less than amalgam (p = 0.000). Bioglass reduced sealing ability of MTA and Geristore® significantly (p = 0.000, p = 0.019), while reduced the sealing ability of amalgam insignificantly (p = 0.78).

Conclusion

MTA and Geristore® have shown acceptable sealing ability in furcal perforation in comparison to amalgam while Bioglass as a matrix beneath them has reduced their sealing ability.     

Physicochemical properties of endodontic sealers of different bases

Objective

To assess the setting time (ST), flow (FL), radiopacity (RD), solubility (SB) and dimensional change following setting (DC) of different sealers (AH Plus^®, Polifil, Apexit Plus^®, Sealapex^®, Endométhasone^® and Endofill^® according to American National Standards Institute/American Dental Association (ANSI/ADA) Specification 57.

Material and methods

Five samples of each material were used for each test. For ST, cast rings were filled with sealers and tested with a Gilmore needle. For FL, the sealer was placed on a glass plate. After 180 s, another plate with 20 g and a load of 100 g were applied on the material, and the diameters of the discs formed were measured. In RD, circular molds were filled with the sealers, radiographed and analyzed using Digora software. For SB, circular molds were filled with the sealers, a nylon thread was placed inside the material and another glass plate was positioned on the set, pressed and stored at 37ºC. Samples were weighed, placed in water, dried and reweighed. The water used for SB was analyzed by atomic absorption spectrometry. For DC, circular molds were filled with the sealers, covered by glass plates and stored at 37ºC. Samples were measured and stored in water for 30 days. After this period, they were dryed and measured again.

Results

Regarding ST, AH Plus^®, Apexit^® and Endofil^® sealers are in accordance with ANSI/ADA standards. Endométhasone''s manufacturer did not mention the ST; Polifil is an experimental sealer and Sealapex^® did not set. Considering RD, SB and DC, all sealers were in accordance with ANSI/ADA. The spectrometric analysis showed that a significant amount of K⁺ and Zn2⁺ ions was released from Apexit Plus^® and Endofill^®, respectively.

Conclusion

Except for DC, all other physicochemical properties of the tested sealers conformed to ANSI/ADA requirements.     

Evaluation of the antimicrobial effect of super-oxidized water (Sterilox®) and sodium hypochlorite against Enterococcus faecalis in a bovine root canal model

Ideally root canal irrigants should have, amongst other properties, antimicrobial action associated with a lack of toxicity against periapical tissues. Sodium hypochlorite (NaOCl) is a widely used root canal irrigant, however it has been shown to have a cytotoxic effect on vital tissue and therefore it is prudent to investigate alternative irrigants. Sterilox''s Aquatine Alpha Electrolyte^® belongs to the group of the super-oxidized waters; it consists of a mixture of oxidizing substances, and has been suggested to be used as root canal irrigant. Super-oxidized waters have been shown to provide efficient cleaning of root canal walls, and have been proposed to be used for the disinfection of medical equipment.

Objective

To compare the antimicrobial action against Enterococcus faecalis of NaOCl, Optident Sterilox Electrolyte Solution^® and Sterilox''s Aquatine Alpha Electrolyte^® when used as irrigating solutions in a bovine root canal model.

Methodology

Root sections were prepared and inoculated with E. faecalis JH2-2. After 10 days of incubation the root canals were irrigated using one of three solutions (NaOCl, Optident Sterilox Electrolyte Solution^® and Sterilox''s Aquatine Alpha Electrolyte^®) and subsequently sampled by grinding dentin using drills. The debris was placed in BHI broth and dilutions were plated onto fresh agar plates to quantify growth.

Results

Sodium hypochlorite was the only irrigant to eliminate all bacteria. When the dilutions were made, although NaOCl was still statistically superior, Sterilox''s Aquatine Alpha Electrolyte^® solution was superior to Optident Sterilox Electrolyte Solution^®.

Conclusion

Under the conditions of this study Sterilox''s Aquatine Alpha Electrolyte^® appeared to have significantly more antimicrobial action compared to the Optident Sterilox Electrolyte Solution^® alone, however NaOCl was the only solution able to consistently eradicate E. faecalis in the model.     

The effect of immobilization of heparin and bone morphogenic protein-2 to bovine bone substitute on osteoblast-like cell's function

PURPOSE

This study was performed to investigate the ability of recombinant human-bone morphogenic protein-2 immobilized on a heparin-grafted bone substrate to enhance the osteoblastic functions.

MATERIALS AND METHODS

The Bio-Oss®, not coated with any material, was used as a control group. In rhBMP-2-Bio-Oss® group, rhBMP-2 was coated with Bio-Oss® using only deep and dry methods (50 ng/mL, 24 h). In heparinized rhBMP-2-Bio-Oss® group, dopamine was anchored to the surface of Bio-Oss®, and coated with heparin. rhBMP-2 was immobilized onto the heparinized- Bio-Oss® surface. The release kinetics of the rhBMP-2-Bio-Oss® and heparinized rhBMP-2-Bio-Oss® were analyzed using an enzyme-linked immunosorbent assay. The biological activities of the MG63 cells on the three groups were investigated via cytotoxicity assay, cell proliferation assay, alkaline phosphatase (ALP) measurement, and calcium deposition determination. Statistical comparisons were carried out by one-way ANOVA test. Differences were considered statistically significant at ^*P<.05 and ^**P<.001.

RESULTS

The heparinized rhBMP-2-Bio-Oss® showed more sustained release compared to the rhBMP-2-Bio-Oss® over an extended time. In the measurement of the ALP activity, the heparinized group showed a significantly higher ALP activity when compared with the non-heparinized groups (P<.05). The MG63 cells cultivated in the group with rhBMP-2 showed increased calcium deposition, and the MG63 cells from the heparinized group increased more than those that were cultivated in the non-heparinized groups.

CONCLUSION

Heparin increased the rhBMP-2 release amount and made sustained release possible, and heparinized Bio-Oss® with rhBMP-2 successfully improved the osteoblastic functions.     

Lack of correlation between tubular dentine cement penetration, adhesiveness and leakage in roots filled with gutta percha and an endodontic cement based on epoxy amine resin

Objective

To analyze possible correlations among tubular dentine cement penetration, adhesiveness and apical leakage in fillings performed with gutta percha and an endodontic cement based on epoxy amine resin.

Material and Methods

Sixty similar, extracted human mandibular central incisors were irrigated, instrumented and filled following the same protocol. First, apical leakage was quantified by fluid filtration tests. Then, these same specimens were sectioned for analysis of tubular dentine cement penetration and the middle thirds were submitted to push-out tests to analyze the adhesiveness of the fillings.

Results

In brief, the means and standard deviations with a confidence interval of 95% were as follows: tubular dentine cement penetration (8.875±4.540), adhesiveness (4.441±2.683) and apical leakage (0.318±0.215). The data were confronted using the Pearson''s test (P>0.05), and it was possible to prove that there was no correlation between (1) tubular dentine cement penetration and apical leakage (r²: 0.08276), (2) tubular dentine cement penetration and adhesiveness (r²: -0.2412) and (3) adhesiveness and apical leakage (r²: 0.1340).

Conclusion

After analysis of these data, it could be observed that there exists no correlation among the variables analyzed in this study.     

A Comparative Study of Shaping Ability of four Rotary Systems

Purpose

This study compared the cutting area, instrumentation time, root canal anatomy preservation and non-instrumented areas obtained by F360^®, Mtwo^®, RaCe^® and Hyflex^® files with ISO size 35.

Material and Methods

120 teeth with a single straight root and root canal were divided into 4 groups. Working length was calculated by using X-rays. The teeth were sectioned with a handpiece and a diamond disc, and the sections were observed with Nikon SMZ-2T stereoscopic microscope and an Intralux 4000-1 light source. The groups were adjusted with a preoperative analysis with AutoCAD. The teeth were reconstructed by a #10 K-File and epoxy glue. Each group was instrumented with one of the four file systems. The instrumentation time was calculated with a 1/100 second chronometer. The area of the thirds and root canal anatomy preservation were analyzed with AutoCAD 2013 and the non-instrumented areas with AutoCAD 2013 and SMZ-2T stereoscopic microscope. The statistical analysis was made with Levene’s Test, ANOVA, Bonferroni Test and Pearson´s Chi-square.

Results

Equal variances were shown by Levene’s Test (P > 0.05). ANOVA (P > 0.05) showed the absence of significant differences. There were significant differences in the instrumentation time (P < 0.05). For root canal anatomy preservation and non-instrumented areas, there were no significant differences between all systems (P > 0.05).

Conclusions

The 4 different rotary systems produced similar cutting area, root canal anatomy preservation and non-instrumented areas. Regarding instrumentation time, F360^® was the fastest system statistically.Key words: Cutting ability, cross-sections, instrumentation time, rotary instruments     

Effects of curing protocol and storage time on the micro-hardness of resin cements used to lute fiber-reinforced resin posts

Objectives

To determine the micro-hardness profile of two dual cure resin cements (RelyX - U100^®, 3M-ESPE and Panavia F 2.0^®, Kuraray) used for cementing fiber-reinforced resin posts (Fibrekor^® - Jeneric Pentron) under three different curing protocols and two water storage times.

Material and methods

Sixty 16mm long bovine incisor roots were endodontically treated and prepared for cementation of the Fibrekor posts. The cements were mixed as instructed, dispensed in the canal, the posts were seated and the curing performed as follows: a) no light activation; b) light-activation immediately after seating the post, and; c) light-activation delayed 5 minutes after seating the post. The teeth were stored in water and retrieved for analysis after 7 days and 3 months. The roots were longitudinally sectioned and the microhardness was determined at the cervical, middle and apical regions along the cement line. The data was analyzed by the three-way ANOVA test (curing mode, storage time and thirds) for each cement. The Tukey test was used for the post-hoc analysis.

Results

Light-activation resulted in a significant increase in the microhardness. This was more evident for the cervical region and for the Panavia cement. Storage in water for 3 months caused a reduction of the micro-hardness for both cements. The U100 cement showed less variation in the micro-hardness regardless of the curing protocol and storage time.

Conclusions

The micro-hardness of the cements was affected by the curing and storage variables and were material-dependent.     

Influence of Kinesiologic Tape on Post-operative Swelling After Orthognathic Surgery

Introduction

Orthognathic surgery involves making several osteotomies that lead to varying degrees of post-operative swelling. The use of KT may be beneficial for postoperative treatment after head and neck surgery, accelerating drainage of tissue reaction or haemorrhages. The goal of this study was to find out if the application of KT prevents or improves swelling, pain and trismus after orthognathic surgery, improving patients’ postoperative quality of life.

Materials and Methods

In this double-blinded, randomized, control trial, 24 patients in whom bimaxillary orthognathic surgery was indicated, were included. Before surgery each patient alternatively was randomly included in the study group (treated with K-Taping^® and corticosteroid) or in the control group (treated with corticosteroid). In the present study a MakerBot^® Digitizer 3D™ was used to assess accurate volume measurements. All swelling measurements were expressed as total 3-D area of the landmarks (cm² ) in T0 pre-operative, T1 fourth day after surgery.

Results

The differences T0–T1 are highly significant (p < 0.01) between group 1 or study group (treated with K-taping^®) and group 2 (control group).

Discussion

The use of KT appears promising, because it is simple to carry out, less traumatic, economical, can be performed everywhere in the world, free from side effects on the body. Even when swelling persists, KT gives patients the impression of a minor swelling detracting them from their pain and morbidity. Further studies have to be performed to find out if KT can reduce or replace the need for additional medications such as the use of steroids.     

Resorption of labial bone in maxillary anterior implant

PURPOSE

The purpose of this study was to evaluate the amount of resorption and thickness of labial bone in anterior maxillary implant using cone beam computed tomography with Hitachi CB Mercuray (Hitachi, Medico, Tokyo, Japan).

MATERIALS AND METHODS

Twenty-one patients with 26 implants were followed-up and checked with CBCT. 21 OSSEOTITE NT® (3i/implant Innovations, Florida, USA) and 5 OSSEOTITE® implants (3i/implant Innovations, Florida, USA) were placed at anterior region and they were positioned vertically at the same level of bony scallop of adjacent teeth. Whenever there was no lesion or labial bone was intact, immediate placement was tried as possible as it could be. Generated bone regeneration was done in the patients with the deficiency of hard tissue using Bio-Oss® (Geistlich, Wolhusen, Switzerland) and Bio-Gide® (Geistlich, Wolhusen, Switzerland). Second surgery was done in 6 months after implant placement and provisionalization was done for 3 months. Definite abutment was made of titanium abutment with porcelain, gold and zirconia, and was attached after provisionalization. Two-dimensional slices were created to produce sagittal, coronal, axial and 3D by using OnDemand3D (Cybermed, Seoul, Korea).

RESULTS

The mean value of bone resorption (distance from top of implant to labial bone) was 1.32 ± 0.86 mm and the mean thickness of labial bone was 1.91 ± 0.45 mm.

CONCLUSION

It is suggested that the thickness more than 1.91 mm could reduce the amount and incidence of resorption of labial bone in maxillary anterior implant.     

Analysis of radiopacity,pH and cytotoxicity of a new bioceramic material

Objective

RetroMTA^® is a new hydraulic bioceramic indicated for pulp capping, perforations or root resorption repair, apexification and apical surgery. The aim of this study was to compare the radiopacity, pH variation and cytotoxicity of this material to ProRoot^® MTA.

Material and Methods

Mixed cements were exposed to a digital x-ray along with an aluminum stepwedge for the radiopacity assay. pH values were verified after incubation period of 3, 24, 48, 72 and 168 hours. The cytotoxicity of each cement was tested on human periodontal ligament fibroblasts using a multiparametric assay. Data analysis was performed using ANOVA and Tukey’s post hoc in GraphPad Prism.

Results

ProRoot^® MTA had higher radiopacity than RetroMTA^® (p<0.001). No significant differences were observed for the pH of the materials throughout experimental periods (p>0.05) although pH levels of both materials reduced over time. Both ProRoot^® MTA and RetroMTA^® allowed for significantly higher cell viability when compared with the positive control (p<0.001). No statistical difference was observed between ProRoot^® MTA and RetroMTA^® cytotoxicity level in all test parameters, except for the ProRoot^® MTA 48-hour extract media in the NR assay (p<0.05).

Conclusion

The current study provides new data about the physicochemical and biological properties of Retro^® MTA concerning radiopacity, pH and cytotoxic effects on human periodontal ligaments cells. Based on our findings, RetroMTA^® meets the radiopacity requirements standardized by ANSI/ADA number 57², and similar pH values and biocompatibility to ProRoot^® MTA. Further studies should be performed to evaluate additional properties of this new material.     

EVALUATION OF APICAL MICROLEAKAGE OF TEETH SEALED WITH FOUR DIFFERENT ROOT CANAL SEALERS

Objectives:

to compare the apical sealing ability of four root canal sealers. Materials and methods: forty extracted human maxillary canines were instrumented 1 mm short of the anatomical apex and randomly assigned to four groups (n=10), according to the root canal sealer used for obturation: Endofill, AH Plus, EndoREZ and Epiphany. Root canals were obturated with guttapercha points, except for the Epiphany group, in which resin points (Resilon) were used. The teeth were immersed in India ink for seven days and clarified using methyl salicylate. The extent of apical dye penetration was measured with a measuroscope in all aspects of the canal.

Results:

AH Plus (0.02 mm ± 0.07), Epiphany (0.00 mm ± 0.00) and EndoREZ (0.32 mm ± 0.62) did not differ statistically to each other (p>0.01). EndoFill presented the highest dye penetration mean (0.83 mm ± 0.73) and was statistically different from the other sealers (p<0.01).

Conclusions:

the resin-based root canal sealers presented lesser apical microleakage than the zinc oxide and eugenol based sealer. No statistical differences were observed among resin based sealers.     

Comparison of debris extruded apically and working time used by ProTaper Universal rotary and ProTaper retreatment system during gutta-percha removal

Objective

The aim of this study was to evaluate the in vitro action of ProTaper retreatment files and ProTaper Universal in the retreatment of mandibular premolars.

Material and methods

The amount of debris extruded apically was measured and the time to reach the working length and to complete the removal of gutta-percha was observed. Thirty teeth had their canals prepared using ProTaper Universal files and were obturated by the single cone technique. The teeth were then stored at 37ºC in a humid environment for 7 days. During the use of the rotary instruments for root canal filling removal, the apical portions of the teeth were attached to the open end of a resin tube to collect the apically extruded debris.

Results

ProTaper Universal files were significantly faster (p=0.0011) than the ProTaper retreatment files to perform gutta-percha removal, but no significant difference was found between the files regarding the time to reach the working length or the amount of apical extrusion.

Conclusions

ProTaper Universal rotary had better results for endodontic retreatment, and both techniques promote similar apical extrusion of debris.     

Influence of root canal sealer on the radiographic appearance of filling voids in maxillary single-rooted teeth

Objective

This study compared the influence of three epoxy resin-based sealers with distinct radiopacities on the observers'' ability to detect root canal filling voids during radiographic analysis.

Material and methods

The root canals of 48 extracted maxillary canines were prepared and divided into three groups. Each group was laterally condensed with one sealer (AH Plus^TM, Acroseal^® or a non-radiopaque sealer), and a longitudinal void was simulated in half of the specimens from each group (n=8). Buccolingual radiographs were obtained and randomly interpreted for voids by a radiologist and an endodontist in a blinded fashion. Teeth were cut and inspected under a microscope to confirm the position of void. Differences in sensitivity and specificity between groups and examiners were compared using the Fisher''s Exact and McNemar tests, respectively (α=0.05).

Results

Significantly lower sensitivity levels (p<0.05) were observed in the coronal portion of fillings performed with both radiopaque sealers. Specificity values for Acroseal^® were significantly higher (p<0.05) in the coronal and apical portions of fillings.

Conclusions

The type of root canal sealer can affect the observers'' ability to detect root canal filling voids during radiographic analysis of upper single-rooted teeth.     

A study on the in-vitro wear of the natural tooth structure by opposing zirconia or dental porcelain

PURPOSE

This study was conducted to evaluate clinical validity of a zirconia full-coverage crown by comparing zirconia''s wear capacity over antagonistic teeth with that of feldspathic dental porcelain.

MATERIALS AND METHODS

The subject groups were divided into three groups: the polished feldspathic dental porcelain group (Group 1), the polished zirconia group (Group 2), and the polished zirconia with glazing group (Group 3). Twenty specimens were prepared from each group. Each procedure such as plasticity, condensation, and glazing was conducted according to the manufacturer''s manual. A wear test was conducted with 240,000 chewing cycles using a dual-axis chewing simulator. The degree of wear of the antagonistic teeth was calculated by measuring the volume loss using a three-dimensional profiling system and ANSUR 3D software. The statistical significance of the measured degree of wear was tested with a significant level of 5% using one-way ANOVA and the Tukey test.

RESULTS

The degrees of wear of the antagonistic teeth were 0.119 ± 0.059 mm³ in Group 1, 0.078 ± 0.063 mm³ in Group 3, and 0.031 ± 0.033 mm³ in Group 2. Statistical significance was found between Group 1 and Groups 2 and between Group 2 and 3, whereas no statistical significance was found between Group 1 and Group 3.

CONCLUSION

Despite the limitations of this study on the evaluation of antagonistic teeth wear, the degree of antagonistic tooth wear was less in zirconia than feldspathic dental porcelain, representing that the zirconia may be more beneficial in terms of antagonistic tooth wear.     

An effect of immediate dentin sealing on the shear bond strength of resin cement to porcelain restoration

PURPOSE

The aim of this study was to determine differences in shear bond strength to human dentin using immediate dentin sealing (IDS) technique compared to delayed dentin sealing (DDS).

MATERIALS AND METHODS

Forty extracted human molars were divided into 4 groups with 10 teeth each. The control group was light-cured after application of dentin bonding agent (Excite® DSC) and cemented with Variolink® II resin cement. IDS/SE (immediate dentin sealing, Clearfil™ SE Bond) and IDS/SB (immediate dentin sealing, AdapterTM Single Bond 2) were light-cured after application of dentin bonding agent (Clearfil™ SE Bond and Adapter™ Sing Bond 2, respectively), whereas DDS specimens were not treated with any dentin bonding agent. Specimens were cemented with Variolink® II resin cement. Dentin bonding agent (Excite® DSC) was left unpolymerized until the application of porcelain restoration. Shear strength was measured using a universal testing machine at a speed of 5 mm/min and evaluated of fracture using an optical microscope.

RESULTS

The mean shear bond strengths of control group and IDS/SE group were not statistically different from another at 14.86 and 11.18 MPa. Bond strength of IDS/SE group had a significantly higher mean than DDS group (3.14 MPa) (P < .05). There were no significance in the mean shear bond strength between IDS/SB (4.11 MPa) and DDS group. Evaluation of failure patterns indicates that most failures in the control group and IDS/SE groups were mixed, whereas failures in the DDS were interfacial.

CONCLUSION

When preparing teeth for indirect ceramic restoration, IDS with Clearfil™ SE Bond results in improved shear bond strength compared with DDS.     

QMix? irrigant reduces lipopolysacharide (LPS) levels in an in vitro model

The presence of endotoxin inside the root canal has been associated with periapical inflammation, bone resorption and symptomatic conditions.

Objectives

To determine, in vitro, the effect of QMix^® and other three root canal irrigants in reducing the endotoxin content in root canals.

Material and Methods

Root canals of single-rooted teeth were prepared. Samples were detoxified with Co-60 irradiation and inoculated with E. coli LPS (24 h, at 37°C). After that period, samples were divided into 4 groups, according to the irrigation solution tested: QMix^®, 17% EDTA, 2% chlorhexidine solution (CHX), and 3% sodium hypochlorite (NaOCl). LPS quantification was determined by Limulus Amebocyte Lysate (LAL) assay. The initial counting of endotoxins for all samples, and the determination of LPS levels in non-contaminated teeth and in contaminated teeth exposed only to non-pyrogenic water, were used as controls.

Results

QMix^® reduced LPS levels, with a median value of 1.11 endotoxins units (EU)/mL (p<0.001). NaOCl (25.50 EU/mL), chlorhexidine (44.10 EU/mL) and positive control group (26.80 EU/mL) samples had similar results. Higher levels were found with EDTA (176.00 EU/mL) when compared to positive control (p<0.001). There was no significant difference among EDTA, NaOCl and CHX groups. Negative control group (0.005 EU/mL) had statistically significant lower levels of endotoxins when compared to all test groups (p<0.001).

Conclusion

QMix^® decreased LPS levels when compared to the other groups (p<0.001). 3% NaOCl, 2% CHX and 17% EDTA were not able to significantly reduce the root canal endotoxins load.