Fracture resistance of immature teeth filled with BioAggregate,mineral trioxide aggregate and calcium hydroxide

Abstract – Background: The aim of this in vitro study was to assess the long‐term fracture resistance of human immature permanent teeth filled with BioAggregate (BA), mineral trioxide aggregate (MTA) and calcium hydroxide (CH). Materials and methods: The study consisted of single rooted premolar teeth with immature root formation extracted for orthodontic reasons. A total of 28 immature premolars with average root length of 10.7 mm and apical diameter of 3 mm were included in the study. The pulps were extirpated and the canals were prepared using an apical approach. The teeth were randomly assigned to four groups: Group I: DiaRoot^® BA (DiaDent, Burnaby, BC, Canada), Group II: Angelus MTA (MTA‐A; Angelus, Londrina, Brazil), Group III: ProRoot^® MTA (MTA‐PR; Dentsply, Tulsa, OK, USA), Group IV: CH (Sultan Chemists Inc., Englewood, NJ, USA). The teeth were placed in saline solution at 4°C for 1 year. The root of each tooth was then embedded in an acrylic resin block. All specimens were loaded at a crosshead speed of 1 mm min^?1 in an Instron testing machine and the peak loads up to fracture were recorded. Data were analysed statistically by Kruskal–Wallis and Mann–Whitney U‐tests. Results: Mean (±SD) failure loads (MPa) were: 37.69 ± 14.43 for BA group, 32.94 ± 8.15 for MTA‐A group, 28.74 ± 9.49 for MTA‐PR group and 23.18 ± 8.48 for CH group. The BA group exhibited the highest fracture resistance and the CH group showed the lowest resistance to fracture. Significant differences (P < 0.05) in fracture resistance were found between the DiaRoot‐BA and CH groups, and also between the MTA‐A and CH groups. Conclusion: Within the limitations of this study, data suggest that DiaRoot‐BA‐filled immature teeth demonstrate higher fracture resistance than other groups at 1 year. Considering the long‐term risk of cervical root fracture associated with immature teeth, the use of DiaRoot‐BA as a root canal filling material appears to be the most advantageous of the materials tested.     

Comparison of the fracture resistance of simulated immature permanent teeth using various canal filling materials and fiber posts

Abstract – Background: The purpose of this study was to compare the fracture resistances of immature teeth treated with MTA along with root canal obturation methods using AH Plus, MetaSEAL, MTA Fillapex sealers + lateral compaction technique, and Unicore quartz fiber posts. Materials and methods: Fifty single‐rooted maxillary anterior teeth were divided into five groups. The crowns were dissected and root canals were enlarged. #6 Peeso reamers were allowed to protrude 1 mm. beyond the apex to simulate immature teeth. The apical 4–5 mm of each tooth was filled using Angelus white MTA. The remaining portions of canals were obturated as follows: Group 1: No backfilling (control), Group 2: AH Plus + gutta‐percha, lateral compaction, Group 3: MetaSEAL + gutta‐percha, lateral compaction, Group 4: MTA Fillapex + gutta‐percha, lateral compaction, Group 5: UniCore Fiber posts luted using PermaFlo DC. The specimens were embedded into self‐curing acrylic poured into identical cylinders which were mounted on a jig providing a 45° angle. A compressive load increasing at 1 mm min^?1 was applied and the maximum load at which fracture occurred was recorded. Statistical analysis was performed using Kruskal–Wallis and Dunn’s multiple tests. Results: The highest fracture resistance was obtained with Group 5 (Fiber posts) whereas Group 4 (MTA Fillapex) yielded the lowest values. The mean fracture resistance value of Group 2 (AH Plus) was significantly higher than Group 4 (MTA Fillapex) (P = 0.001). The mean fracture value of Group 5 (Fiber posts) was significantly higher than Group 2 (AH Plus), Group 3 (MetaSEAL), and Group 4 (MTA Fillapex) (P = 0.02, 0.004, and 0.0001, respectively). Conclusion: Within the limitations of this study, UniCore quartz fiber posts provided the highest resistance. This methodology may specifically be advantageous for teeth with arrest of development at early stages, as these teeth are more susceptible to fracture owing to their excessively weak dentinal walls.     

Scanning electron microscopy evaluation of the hard tissue barrier after pulp capping with calcium hydroxide,mineral trioxide aggregate (MTA) or ProRoot MTA

The aim of this study was to investigate the morphology and localisation of calcium hydroxide‐ and mineral trioxide aggregate (MTA)‐induced hard tissue barriers after pulpotomy in dogs' teeth. Pulpotomies were performed on maxillary and mandibular premolars of five dogs. The teeth were assigned into three groups according to the pulp‐capping agent used. The pulpal wounds were capped with calcium hydroxide (Ca(OH)₂– control), MTA or ProRoot MTA, and the cavities were restored with amalgam. After a 90‐day follow‐up period, the dogs were euthanised and the teeth were examined under scanning electron microscopy (SEM). An image‐processing and analysis software was used to delimit the perimeters of the root canal area and the hard tissue barrier to determine the percentage of root canal obliteration. SEM data were used to assess the morphology, localisation and extension of the reparative hard tissue barriers. ProRoot MTA was statistically different from MTA and Ca(OH)₂ (P < 0.05) regarding tissue barrier morphology. Localisation data showed that ProRoot MTA was significantly different from Ca(OH)₂ (P < 0.05) and similar to MTA (P > 0.01; P > 0.05). No statistically significant difference (P > 0.01; P > 0.05) was observed between MTA and Ca(OH)₂. A larger number of complete (centroperipheral) hard tissue barriers with predominance of dentinal tubules was observed to the ProRoot MTA when compared with the Ca(OH)₂ group.     

Evaluation of cytotoxicity and up-regulation of gelatinases in fibroblast cells by three root repair materials

Silva EJNL, Herrera DR, Almeida JFA, Ferraz CCR, GomesBPFA, Zaia AA. Evaluation of cytotoxicity and up‐regulation of gelatinases in fibroblast cells by three root repair materials. International Endodontic Journal,  45 , 815–820, 2012. Aim To investigate the effects of root repair materials on the cytotoxicity and gelatinolytic activity of matrix metalloproteinases (MMPs) in 3T3 fibroblasts. Methodology Fibroblasts (3T3, 3 × 10⁵ cells per well) were incubated with elutes of calcium hydroxide (Biodinâmica, Ibiporã, PR, Brazil), EndoBinder (Binderware, São Carlos, SP, Brazil) and mineral trioxide aggregate (MTA) (Angelus, Londrina, PR, Brazil) for 24 h. The cytotoxicity of all root repair materials was determined using the MTT assay. Supernatants of cell cultures incubated with materials were collected after 24 h to determine the levels of MMP‐2 and MMP‐9 gelatinolytic activity by gelatin zymography. Data were analysed using anova and Tukey’s test. Results Cells secreted MMP‐2 after 24 h with calcium hydroxide inducing significantly greater MMP‐2 expression in relation to the control and the other root repair materials (P < 0.05). The cytotoxicity results revealed that there was no significant difference in the cell viability of MTA, EndoBinder and the control group. However, there was a significantly reduced cell viability of 3T3 fibroblasts in association with calcium hydroxide (P < 0.05). Conclusions Calcium hydroxide was associated with significantly less cell viability when compared with EndoBinder and MTA. All materials had gelatinolytic activity for MMP‐2 with calcium hydroxide being associated with the greatest activity.     

Evaluation of mineral trioxide aggregate (MTA) versus calcium hydroxide cement (Dycal(®) ) in the formation of a dentine bridge: a randomised controlled trial

Aim: To assess the effectiveness of mineral trioxide aggregate (MTA) used as an indirect pulp‐capping material in human molar and premolar teeth. Methodology: We conducted a clinical evaluation of 60 teeth, which underwent an indirect pulp‐capping procedure with either MTA or calcium hydroxide cement (Dycal^®). Calcium hydroxide was compared with MTA and the thickness of the newly formed dentine was measured at regular time intervals. The follow‐up was at 3 and 6 months, and dentine formation was monitored by radiological measurements on digitised images using Mesurim Pro^® software. Results: At 3 months, the clinical success rates of MTA and calcium hydroxide were 93% and 73%, respectively (P = 0.02). At 6 months, the success rate was 89.6% with MTA, and remained steady at 73% with calcium hydroxide (P = 0.63). The mean initial residual dentine thickness was 0.23 mm, and increased by 0.121 mm with MTA and by 0.136 mm with calcium hydroxide at 3 months. At 6 months, there was an increase of 0.235 mm with MTA and of 0.221 mm with calcium hydroxide. Conclusions: A higher success rate was observed in the MTA group relative to the Dycal^® group after 3 months, which was statistically significant. After 6 months, no statistically significant difference was found in the dentine thickness between the two groups. Additional histological investigations are needed to support these findings.     

Effect of fibre‐reinforced composite on the fracture resistance of endodontically treated teeth

The aim of this study is to evaluate the fracture resistance of root‐filled teeth restored with fibre‐reinforced composite (everX posterior). Fifty mandibular molars were divided into five groups (n = 10). Group 1: no treatment was applied (intact teeth). Group 2–5: canals were prepared and root filled. Group 2: no coronal restoration was placed. Group 3: teeth were coronally restored with composite. Group 4: composite restorations were performed following polyethylene fibre insertion at the cavity base. Group 5: composite resin placed over everX posterior. After thermocycling (5–55°C, 5000×), fracture resistance was measured. Mean force load for each sample was recorded in Newtons (N). Results were statistically analysed with one‐way analysis of variance and post hoc Tukey's tests. The mean force required to fracture samples and standard deviations are as follows: group 1: 2859.5 ± 551.27 N, group 2: 318.97 ± 108.67 N, group 3: 1489.5 ± 505.04 N, group 4: 1958.3 ± 362.94 N, group 5: 2550.7 ± 586.1 N. everX posterior (group 5) was higher than groups 2, 3 and 4 (P < 0.05). There were no significant differences between everX posterior and intact teeth (P > 0.05). Placing fibre‐reinforced composite under composite increased the fracture strength of root‐filled teeth to the level of intact teeth.     

Push‐out bond strength of two root‐end filling materials in root‐end cavities prepared by Er,Cr:YSGG laser or ultrasonic technique

This study compared the push‐out bond strength of mineral trioxide aggregate (MTA) and a new endodontic cement (NEC) as root‐end filling materials in root‐end cavities prepared by ultrasonic technique (US) or Er,Cr:YSGG laser (L). Eighty single‐rooted extracted human teeth were endodontically treated, apicectomised and randomly divided into four following groups (n = 20): US/MTA, US/NEC, L/MTA and L/NEC. In US/MTA and US/NEC groups, root‐end cavities were prepared with ultrasonic retrotip and filled with MTA and NEC, respectively. In L/MTA and L/NEC groups, root‐end cavities were prepared using Er,Cr:YSGG laser and filled with MTA and NEC, respectively. Each root was cut apically to create a 2 mm‐thick root slice for measurement of bond strength using a universal testing machine. Then, all slices were examined to determine the mode of bond failure. Data were analysed using two‐way anova . Root‐end filling materials showed significantly higher bond strength in root‐end cavities prepared using ultrasonic technique (US/MTA and US/NEC) (P < 0.001). The bond strengths of MTA and NEC did not differ significantly. The failure modes were mainly adhesive for MTA, but cohesive for NEC. In conclusion, bond strengths of MTA and NEC to root‐end cavities were comparable and higher in ultrasonically prepared cavities.     

The effect of mineral trioxide aggregate on the apexification and periapical healing of teeth with incomplete root formation

Aim To evaluate the influence of mineral trioxide aggregate (MTA) on apexification and periapical healing of teeth in dogs with incomplete root formation and previously contaminated canals and to verify the necessity of employing calcium hydroxide paste before using MTA. Methodology Twenty premolars from two 6‐month old dogs were used. After access to the root canals and complete removal of the pulp, the canal systems remained exposed to the oral environment for 2 weeks. Canal preparation was then carried out using Hedström files, under irrigation with 1% sodium hypochlorite, 1 mm short of the radiographic apex. After drying, the canals of two premolars in each dog were left empty (control group). The other eight teeth in each animal were divided into two experimental groups. The apical thirds of the canals of group 1 were filled with MTA. In the teeth of group 2, the canals were dressed with a calcium hydroxide–propylene glycol paste. After 1 week, the paste was removed and the apical third was filled with MTA. All teeth were restored with reinforced zinc oxide cement (IRM) and amalgam. The animals were killed 5 months later, and blocks of the teeth and surrounding tissues were submitted to histological processing. The sections were studied to evaluate seven parameters: formation of an apical calcified tissue barrier, level of barrier formation, inflammatory reaction, bone and root resorption, MTA extrusion, and microorganisms. Results of experimental groups were analysed by Wilcoxon's nonparametric tests and by the test of proportions. The critical value of statistical significance was 5%. Results Significant differences (P < 0.05) were found in relation to the position of barrier formation and MTA extrusion. The barrier was formed in the interior of the canal in 69.2% of roots from MTA group only. In group 2, it was formed beyond the limits of the canal walls in 75% of the roots. MTA extrusion occurred mainly in roots from group 2. There was similarity between the groups for the other parameters. Conclusions Mineral trioxide aggregate used after root canal preparation favoured the occurrence of the apexification and periapical healing. The initial use of calcium hydroxide paste was not necessary for apexification to occur, and has shown to be strongly related to the extrusion of MTA and formation of barriers beyond the limits of the root canal walls.     

Fracture resistance of endodontically treated mandibular first molars with conservative access cavity and different restorative techniques: An in vitro study

The aim was to investigate in vitro the fracture resistance (FR) of endodontically treated teeth (ETT) with conservative access cavity restored using various direct and indirect restorative materials and techniques. Seventy‐two mandibular first molars were equally divided into six groups. Teeth in Group 1 were untreated (controls). In Groups 2, 3, 4, 5 and 6, teeth were restored with amalgam, composite resin, ceramic inlay, ceramic onlay and zirconium crown, respectively. A fracture test was performed on all teeth using a static load. Compared with other groups, teeth in Groups 3 (P < 0.05) and 6 (P < 0.05) had the highest FR values with no significant difference in‐between them. Teeth in Group 4 had the lowest FR than other groups (P < 0.05). All restorative techniques tested led to a significant reduction in FR. It is necessary to consider type of fracture when evaluating fracture resistance of endodontically treated teeth. Crowned molars had the highest favourable fractures among the five treatment groups. Although the results of this in vitro study showed variations between tested techniques in ETT with a conservative access cavity, further long‐term controlled clinical trials are required to confirm these in vitro findings.     

Treatment of open apex teeth using two types of white mineral trioxide aggregate after initial dressing with calcium hydroxide in children

Abstract – Background: The clinical and radiographic success of two types of white mineral trioxide aggregate (MTA) as apical barriers in non‐vital immature permanent incisors in children was investigated. Materials and methods: Following an initial dressing with calcium hydroxide, MTA apical barriers were placed in 22 non‐vital traumatized, permanent incisors with open apices in 21 children (mean age 10 years). Teeth were alternately assigned to either white MTA ProRoot^® or white MTA Angelus groups and treated by two operators. Clinical and radiographic reviews took place at baseline, 3 months and every 6 months thereafter. Two other calibrated, blinded examiners evaluated all radiographs. Examiner agreement was assessed using Kappa–Cohen tests. Results were analysed using Fisher’s exact tests and repeated measures anova . Results: The mean follow‐up time was 23.4 months. There were no statistically significant differences in clinical or radiographic outcomes between the two groups. The overall clinical success and relative radiographic success rate was 95.5%. Statistically significant reduction in periapical pathosis was shown over time in both groups (P < 0.05). A significant relationship was identified between non‐divergent apical anatomy and ideal positioning of the MTA plug in all teeth (P = 0.04). Interestingly, coronal discolouration was observed in 22.7% of teeth following white MTA placement. Conclusions: Apical barrier placement using both white MTA ProRoot^® and white MTA Angelus after an initial calcium hydroxide dressing showed similar favourable clinical and radiographic outcomes.     

Smoking and matrix metalloproteinases,neutrophil elastase and myeloperoxidase in chronic periodontitis

Oral Diseases (2010) 17 , 68–76 Objectives: To investigate possible relationship between smoking and serum concentrations of matrix metalloproteinase‐8,‐9 (MMP‐8, MMP‐9), tissue inhibitor of matrix metalloproteinases‐1 (TIMP‐1), neutrophil elastase (NE), myeloperoxidase (MPO) in chronic periodontitis (CP) patients relative to periodontally healthy subjects. Methods: Serum samples were obtained from 111 subjects before initiation of any periodontal intervention. Fifty‐five CP patients (39 non‐smokers, 16 smokers) and 56 periodontally healthy subjects (39 non‐smokers, 17 smokers) were recruited. Serum concentrations of MMP‐8 were determined by IFMA and MPO, MMP‐9, TIMP‐1, NE concentrations by ELISA. ANCOVA and Pearson correlation analysis was utilized for statistical analysis. Results: Serum MPO, NE concentrations were higher in smoker CP than non‐smoker CP patients (P = 0.002 and P < 0.001, respectively), whereas these were similar in smoker, non‐smoker periodontally healthy groups (P > 0.05). TIMP‐1 concentration was higher in non‐smoker CP than smoker CP group (P < 0.05). MMP‐9/TIMP‐1 ratios were higher in smoker CP than non‐smoker CP group (P = 0.01). MMP‐8 concentrations, MMP‐8/TIMP‐1 and MMP‐9/TIMP‐1 ratios in CP group were not significantly different from those in periodontally healthy group (P > 0.05). Conclusions: Our findings of significantly elevated serum MMP‐9, MPO, NE together with decreased TIMP‐1 in smoker CP patients than non‐smokers support that smoking together with periodontal destruction may expose/predispose to cardiovascular diseases.     

Proteolytic Mediators in Gestational Diabetes Mellitus and Gingivitis

Background: This study evaluates levels of matrix metalloproteinase (MMP)‐8, MMP‐9, and tissue inhibitor of MP‐1 (TIMP‐1) in biofluids of women with gestational diabetes mellitus (GDM) and systemically healthy counterparts with different statuses of periodontal health. Methods: Seventy‐one women with GDM and gingivitis (Gg), 30 women with GDM and healthy periodontium (Gh), 28 systemically and periodontally healthy women (Hh), and 37 systemically healthy women with gingivitis (Hg) were evaluated. MMP‐8, MMP‐9, and TIMP‐1 levels were determined in gingival crevicular fluid (GCF), saliva, and serum by immunofluorometric and enzyme‐linked immunosorbent assays. Full‐mouth clinical periodontal parameters were recorded. Results: GCF and serum MMP‐8 concentrations, serum MMP‐9 concentrations, and serum MMP‐8/MMP‐1 and MMP‐9/MMP‐1 molar ratios were significantly higher in Gg compared with Hg group (P <0.05). Serum MMP‐8 levels and salivary TIMP‐1 levels were higher in Gh compared with Hg group (P <0.05) whereas salivary MMP‐8/TIMP‐1 molar ratio was lower in Gh compared with Hg group (P <0.05). Elevated concentrations of GCF MMP‐8 and MMP‐9 were found in Gg compared with Gh group (P <0.05). Significant correlations were found between local levels of biomarkers and clinical periodontal parameters in only GDM group. Conclusion: GDM may modulate both local and circulating levels of MMP‐8 especially when associated with gingivitis.     

MTA复合纤维粘连蛋白盖髓的临床疗效评价

目的 :观察MTA复合纤维粘连蛋白作为活髓保存剂的临床疗效。方法 :选择 10 9名患者 ,分别用MTA、MTA复合纤维粘连蛋白和氢氧化钙盖髓 ,评价盖髓后 4周与 12周时的盖髓成功率。结果 :盖髓 4周时 ,MTA、MTA复合纤维粘连蛋白和氢氧化钙组的盖髓成功率的差别无统计意义 (P >0 .0 5 )。盖髓 12周时 ,3组材料的盖髓成功率的差别有统计意义 (P <0 .0 5 )。结论 :MTA复合纤维粘连蛋白的临床盖髓效果显著 ,优于氢氧化钙组     

Evaluation of Systemic Levels of Neutrophilic Enzymes in Patients With Hypertension and Chronic Periodontitis

Background: Inflammation stimulates neutrophils to release their enzymes into the extracellular matrix. The aim of the present study is to investigate the serum levels of matrix metalloproteinase (MMP)‐8, MMP‐9, tissue inhibitor of MMP (TIMP)‐1, myeloperoxidase (MPO), and neutrophil elastase (NE) in patients with hypertension and chronic periodontitis (CP). Methods: A total of 95 patients were included in the study. Patients were categorized into three groups: healthy control (n = 29), hypertensive control (n = 32), and hypertensive CP (n = 34). Periodontal parameters were recorded, and serum samples were collected from each participant. Serum MMP‐8, MMP‐9, TIMP‐1, MPO, and NE levels in circulation were assessed by enzyme‐linked immunosorbent assay. Results: The hypertensive CP group had significantly higher serum MMP‐8, MMP‐9, and NE levels than the healthy control group (P <0.05). All study groups had similar serum TIMP‐1 levels (P >0.05). Significantly higher serum MPO levels were detected in patients with hypertension and CP than healthy controls and hypertensive controls (P <0.05); however, the difference in serum MPO levels was not significant between the healthy controls and hypertensive controls (P >0.05). There was no significant difference in MMP‐8/TIMP‐1 ratio among the study groups (P >0.05). MMP‐9/TIMP‐1 ratio was significantly higher in patients with hypertension and CP than healthy controls (P <0.05). Conclusions: The presence of hypertension along with CP has a considerable effect on serum neutrophilic enzyme levels, except TIMP‐1. However, the levels of these enzymes do not seem to be affected by the presence of hypertension only. Further studies including patients who have only CP might help illuminate the effect of CP on these enzymes in patients with hypertension.     

Long-term calcium hydroxide as a root canal dressing may increase risk of root fracture

Abstract – It has been proposed (Cvek 1992) that immature teeth are weakened by filling of the root canals with calcium hydroxide dressing and gutta-percha. The aim of the present study was to test the hypothesis that dentin in contact with calcium hydroxide would show a reduction in fracture strength after a certain period of time. Immature mandibular incisors from sheep were extracted and divided into two experimental groups. Group 1: the pulps were extirpated via the apical foramen. The root canals were then filled with calcium hydroxide (Calasept^®) and sealed with IRM^® cement, and the teeth were then stored in saline at room temperature for 0.5, 1, 2, 3, 6, 9, or 12 months. Group 2: the pulps were extirpated and the root canals were filled with saline and sealed with IRM^® cement. The teeth were then stored in saline for 2 months. Intact teeth served as controls and were tested immediately after extraction. All teeth were tested for fracture strength in an Instron testing machine at the indicated observation periods. The results showed a markedly decrease in fracture strength with increasing storage time for group 1 (calcium hydroxide dressing). The results indicate that the fracture strength of calcium hydroxide-filled immature teeth will be halved in about a year due to the root filling. The finding may explain the frequent reported fractures of immature teeth filled with calcium hydroxide for extended periods.     

Substance P regulates the expression of matrix metalloproteinases and tissue inhibitors of metalloproteinase in cultured human gingival fibroblasts

Background and Objective: Substance P may play a role in the pathogenesis of periodontal disease; however, its mechanisms of modulation are not clear. This study evaluated the effect of two concentrations of Substance P on the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in cultured human gingival fibroblasts. Material and Methods: Fibroblasts were stimulated for 48 h with 10^?4 or 10^?9 m Substance P; untreated fibroblasts served as controls. The expression of MMP‐1, ‐2, ‐3, ‐7 and ‐11 and of TIMP‐1 and ‐2 was evaluated using real‐time polymerase chain reaction and western blotting. Results: There was a significant, concentration‐dependent stimulatory effect of Substance P on MMP‐1, ‐2, ‐3 and ‐7 and TIMP‐2 gene expression (p < 0.05), and a probable effect on MMP‐11 (p = 0.06). At the higher concentration (10^?4 m Substance P), MMP‐1, ‐2, ‐3, ‐7 and ‐11 and TIMP‐2 showed the greatest up‐regulation; at the lower concentration (10^?9 m Substance P), MMP‐1, ‐3 and ‐7 and TIMP‐2 exhibited diminished up‐regulation, with MMP‐2 and ‐11 showing down‐regulation (p < 0.05). Expression of TIMP‐1 was not affected by Substance P (p > 0.05). Western blotting confirmed that Substance P up‐regulated MMP‐1, ‐2, ‐3 and ‐11 and TIMP‐2. MMP‐1, ‐3 and ‐11 and TIMP‐2 showed greater up‐regulation at the higher Substance P concentration and diminished up‐regulation at the lower concentration. MMP‐2 was up‐regulated to a similar degree at both Substance P concentrations. Conclusion: In gingival fibroblast cells, Substance P at the higher concentration (10^?4 m ) induced greater up‐regulation of MMP‐1, ‐3 and ‐11 and TIMP‐2 expression, but at the lower concentration (10^?9 m ) induced diminished up‐regulation, which may represent a mechanism for modulating periodontal breakdown.     

Efficacy of XP‐endo finisher and TRUShape 3D conforming file compared to conventional and ultrasonic irrigation in removing calcium hydroxide

The aim of this study was to compare the efficacy of the XP‐endo Finisher and TRUShape 3D Conforming File to conventional and ultrasonic irrigation techniques for removing calcium hydroxide from artificially created grooves on root canals. The study used 32 human mandibular premolar teeth, which were decoronated and instrumented up to ProTaper Universal F5 (Dentsply Maillefer; Ballagiues, Switzerland). The teeth were split longitudinally, two standardised grooves were prepared in the apical and coronal portions and filled with calcium hydroxide. Each tooth was reassembled with wax. The samples were stored at 100% humidity at 37°C for 1 week, after which the specimens were grouped and irrigated using needle irrigation, ultrasonic irrigation, XP‐endo Finisher via continuous irrigation or TRUShape 3D Conforming File via continuous irrigation. Two calibrated observers scored the amount of calcium hydroxide remaining, and the data were statistically analysed using the Kruskal–Wallis and Mann–Whitney U‐tests, (P < 0.05). Needle irrigation had the poorest scores (P < .001), while the XP‐endo Finisher, TRUShape 3D Conforming File via continuous irrigation and ultrasonic irrigation groups had similar results in removing calcium hydroxide.     

Effect of Mineral Trioxide Aggregate Apical Plug Thickness on Fracture Resistance of Immature Teeth

Introduction

The aim of this study was to compare the fracture resistance of simulated immature teeth after using different thicknesses of mineral trioxide aggregate (MTA) apical plugs.

Evaluation of long-term calcium hydroxide treatment in avulsed teeth — an in vivo study

Calcium hydroxide has been advocated for use in avulsed teeth as a temporary dressing in an attempt to prevent or inhibit external resorption. However, there have been no long-term histological studies that have examined gutta-percha versus calcium hydroxide treatment in avulsed teeth. The purpose of this study was to determine the long-term therapeutic effect of calcium hydroxide therapy in avulsed teeth. Six adult macaca monkeys were anesthetized and all four maxillary incisors were extracted and bench-dried for 25 min. The teeth were replanted and splinted with composite for approximately 2 weeks. Each animal served as its own control and the teeth were accessed, instrumented, and filled with either Ca(OH)₂ or gutta-percha and AH26 cement. All access openings were filled with composite. The Ca(OH)₂ was replaced twice during the experimental period (approximately every 8 weeks). The animals were killed between 5 and 7.5 months postavulsion. The teeth were removed, sectioned, and examined histologically by two examiners. The results of the histological evaluation of external resorption indicated that there were no statistically significant differences in resorption indices between the teeth obturated with gutta percha or with calcium hydroxide (P>0.05). Replacement resorption was the primary cause of root destruction and only a few histological sections exhibited evidence of inflammatory resorption.     

In vitro evaluation of the apical seal of two different retrograde filling materials

To determine whether the selection of retrograde filling material or the choice of instruments in root tip resection influences the seal of the retrograde root filling. Seventy‐two single‐rooted teeth were used. Root resection was performed using a Lindemann bone cutter, a Lindemann bone cutter with A‐shaped cutting design or a diamond‐coated bur. Retro‐cavities were prepared by piezo‐tips and filled with Super‐EBA or MTA. Teeth were made transparent and dye penetration was assessed. Teeth filled with MTA, irrespective of the resection instrument, showed no measurable dye penetration. All groups filled with Super‐EBA showed an apical leakage. There were no significant differences between the three groups filled with Super‐EBA (P = 0.09). The comparison of MTA versus Super‐EBA showed significant superiority in apical seal in favour of MTA (P < 0.0001). To use MTA as a retrograde filling material showed superior results in terms of the tightness of the apical seal as compared to Super‐EBA.