Evaluation of XP-endo Shaper, Reciproc Blue, and ProTaper Universal NiTi Systems on Dentinal Microcrack Formation Using Micro-Computed Tomography.

INTRODUCTION: The purpose of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with XP-endo Shaper (XP), Reciproc Blue (RB), and ProTaper Universal (PTU) instruments using micro-computed tomographic (µCT) analysis. METHODS: Thirty extracted mandibular first and second molars with mesial roots having 2 separate canals with an angle between 10°and 20° were randomly assigned to 3 experimental groups (n = 10) according to the different nickel-titanium systems used for root canal preparation: XP, RB, and PTU. The specimens were scanned using µCT imaging before and after root canal preparation. Then, preoperative and postoperative cross-sectional images of the teeth were evaluated to identify the presence of dentinal defects. For each group, the number of microcracks was determined as a percentage rate. The McNemar test was used to determine significant differences before and after instrumentation. The level of significance was set at P ≤ .05. RESULTS: No new dentinal microcracks were observed in the XP and RB groups. The PTU system significantly increased the percentage rate of microcracks compared with preoperative specimens (P < .05). CONCLUSIONS: Root canal preparations with XP and RB systems might not induce the formation of new dentinal microcracks on the mesial roots of mandibular molars. Further assessments are suggested for the examination of the morphology of microcracks after the use of these instruments.

Temporomandibular joint findings in patients with rheumatoid arthritis, ankylosing spondylitis, and primary Sjögren's syndrome.

AIM: The aim of the present study was to investigate the prevalence of temporomandibular joint (TMJ) symptoms in rheumatoid arthritis (RA), primary Sjögren's syndrome (pSS), and ankylosing spondylitis (AS) patients. METHODS: The present study consisted of 79 individuals with various rheumatic disease (study group: 39 with RA, 17 with AS, 23 with pSS) and 79 age- and sex-matched healthy controls (control group). Subjective symptoms of the TMJ were recorded by means of a questionnaire. And stomatognathic examination was then performed. RESULTS: The prevalence of subjective symptoms in patients with rheumatic disease (73.4%) were significantly higher than that of the controls (22.8%; P<.05). The most common objective symptoms were pain during lateral TMJ palpation (29.1% of patients overall, 8.9% of controls) and mandibular movements (19% of patients overall, 2.5% of controls), and muscle pain during palpation (38% of patients overall, 3.8% of controls). They were significantly higher in all of the rheumatic patients than the controls (P<.05). There was not a statistically-significant difference in the values for mandibular movements between the study and control groups (P>.05, Mann-Whitney U test). CONCLUSIONS: TMJ symptoms were observed to be higher in the patients with RA, AS and pSS than the control group. Dentists and rheumatologists should be aware of TMJ symptoms in patients with rheumatic diseases.

Apical microleakage of different root canal sealers after use of maleic acid and EDTA as final irrigants.

This study aimed to compare the effects of ethylenediaminetetraacetic acid (EDTA) and maleic acid (MA) on the sealing ability of various root canal sealers. Eighty root canals were instrumented and irrigated with either EDTA or MA. They were divided into eight experimental groups and obturated as follows: Group 1: MA + Hybrid Root SEAL/gutta-percha. Group 2: EDTA + Hybrid Root SEAL/gutta-percha. Group 3: MA + iRoot SP/gutta-percha. Group 4: EDTA + iRoot SP/gutta-percha. Group 5: MA + EndoREZ/EndoREZ points. Group 6: EDTA + EndoREZ/EndoREZ points. Group 7: MA + AH Plus/gutta-percha. Group 8: EDTA + AH Plus/gutta-percha. Another ten roots were used as negative and positive controls. The microleakage of each sample was measured at 2-min intervals for 8 min using the fluid filtration method. Data were statistically analyzed with one-way ANOVA, post-hoc Tukey, and paired-samples t tests. The minimum microleakage values were obtained from the teeth obturated with AH Plus and EndoREZ selaers (p < 0.001). The samples with Hybrid Root SEAL showed the maximum leakage (p < 0.001). There were significant differences between the groups irrigated with MA or EDTA in terms of microleakage (p < 0.05). Use of MA resulted in higher microleakage values compared with those using EDTA. The type of final irrigation solution seems to influence the postobturation apical seal. Use of AH Plus and EndoREZ sealers showed better sealing ability compared with IRoot SP and Hybrid Root SEAL.

In vitro evaluation of the minimum bactericidal concentrations of different root-end filling materials.

AIM: The aim of this study was to evaluate the minimum bactericidal concentrations (MBC) of root-end filling materials ProRoot MTA, MTA Angelus and IRM. MATERIALS AND METHODS: Macrodilution broth method was used. Microorganisms used were: Staphylococcus aureus (ATCC 29213), Enterococcus faecalis (ATCC 29212) and Streptococcus mutans. Serial two-fold dilutions of root-end filling samples were prepared in macrodilution tubes with concentrations ranging from 1/2 to 1/512. The samples dilutions were incubated for 24 hours. After incubation, 0.1 ml of diluted culture was inoculated onto the surface of supplemented sheep blood agar (Merck, Germany) and all plates were incubated at 37°C in aerobic condition for 24 hours. The MBC was defined as the lowest concentration of root-end filling samples where no growth was recorded. RESULTS: MBC of both mineral trioxide aggregate (MTA) products against S. aureus were recorded as 15.62 mg/ml and for IRM 31.25 mg/ml MBC for both MTA groups against E. faecalis were recorded as 31.25 mg/ml and for IRM 62.5 mg/ml. MBC of all root-end filling samples against S. mutans were recorded as 62.5 mg/ml. CONCLUSION: All tested root-end filling materials showed acceptable MBC against S. aureus and E. faecalis. CLINICAL SIGNIFICANCE: All tested materials can be used safely for filling of a root-end cavity.

Sealing ability of retrofilling materials following various root-end cavity preparation techniques.

The aim of this study is to compare the sealing efficacy of the retrograde cavity preparations prepared and filled with different equipment and materials. In the study, low speed burs, ultrasonic or Er, Cr:YSGG laser devices were used for cavity preparations and ProRoot MTA and MTA-Angelus as filling materials. Seventy-eight single-rooted teeth were instrumented, root filled, and grouped. Root-end cavities were prepared and filled by using the following: Group 1: Low-speed carbide bur + ProRoot MTA; Group 2: Low-speed bur + MTA-Angelus; Group 3: Ultrasonic retrotips + ProRoot MTA; Group 4: Ultrasonic retrotips + MTA-Angelus; Group 5: Er, Cr:YSGG laser tips + ProRoot MTA; Group 6: Er, Cr:YSGG laser tips + MTA-Angelus. Microleakage was measured using a fluid filtration technique. Differences in the fluid movement among groups were analyzed with a two-way analysis of variance (ANOVA) and LSD test. The results showed a significant difference between the groups prepared with laser and carbide bur (p < 0.05). No difference was found between root-end filling materials (p > 0.05). According to the results of the study, the cavities prepared with Er, Cr:YSGG laser demonstrated significantly lower microleakage in all the filling materials considered.

Comparison of apical and coronal sealing in canals having tapered cones prepared with a rotary NiTi system and stainless steel instruments.

The purpose of this study was to compare the sealing ability of different tapered gutta percha cones that were used with lateral compaction and single cones in canals prepared with various root canal instruments. One hundred extracted maxillary incisor roots were used. In group 1, 30 roots were prepared with stainless steel instruments (SS) and then filled by the lateral compaction technique using .02 tapered master cones. In group 2, 30 roots were prepared with ProFile nickel titanium instruments (NiTi) and filled in the same way as group 1. In group 3, 30 roots were filled by the single cone technique using 0.06 tapered gutta-percha cones. The remaining 10 teeth were taken as two control groups. Apical and coronal leakage was evaluated using the fluid filtration model. Considering the effects of the instrumentation, no statistically significant differences were found between the groups prepared with SS and NiTi (P > 0.05). When the effects of obturation technique were taken into consideration, the ProFile instruments and lateral compaction resulted in significantly less coronal leakage than the SS instruments and lateral compaction (P < 0.05). There were no significant differences in apical leakage among any of the groups (P > 0.05).

Finite element analysis of the effects of thermal obturation in maxillary canine teeth.

OBJECTIVE: The purpose of the present study was to determine the distribution and level of temperature, in a model of a maxillary canine, the surrounding periodontal tissues, and the bones, during a System B heat obturation technique simulation. STUDY DESIGN: The temperature distribution was determined by using a three-dimensional finite element analysis. The tooth was assumed to have undergone an endodontic treatment before the application. Heat applications of 200 degrees C and 100 degrees C were considered. RESULTS: By using the virtual model and the simulation technique, the maximum temperature in the periodontal ligament was found to be 43.5 degrees C. CONCLUSIONS: Within the assumptions and the limitations of the study, it was determined that the simulation of System B technique created no potentially harmful levels of temperature throughout the maxillary canine model.

In vitro inhibition of caries-like lesions with fluoride-releasing materials.

The aim of this study was to compare the in vitro caries inhibition of various resin-based materials. Class V cavities were prepared in twenty-five freshly extracted human premolar teeth which were then restored with glass-ionomer cement (Chemfill II), compomer (Compoglass F, Dyract AP) and composite resin (Tetric Ceram and Z 100). The teeth were submerged in an acid gel for 6 weeks. Each specimen was sectioned. These sections were left in water for 24 hours, and then examined using polarized light microscopy. The lesion consisted of two parts, the outer surface lesion and the cavity wall lesion. There was no significant difference in the body depth of the outer lesion and in the depth of the wall lesion among teeth restored with Compoglass F, Dyract AP and Chemfill II (P > 0.05). There was a significant difference between those restored with Z 100 and Tetric Ceram (P < 0.05). The length of the wall lesion for the teeth restored with Chemfill II was significantly smaller than that in the remaining groups (P < 0.05). The length of the wall lesion for teeth restored with Tetric Ceram and Z 100 was significantly higher than in the remaining groups (P < 0.05). These results suggest that composite materials and compomer provide less caries inhibition than glass-ionomer cements.

Stress distribution of post-core applications in maxillary central incisors.

The purpose of this study was to evaluate the stress distribution in a maxillary central incisor restored with various post-core applications. The study used a three-dimensional finite element method. The tooth was assumed to be endodontically treated with a porcelain crown. Two different sizes of Flexi-post, Cera-post, and Composipost were compared for 200 N palatal and incisal loads. It was determined that, purely from the point of view of strength considerations, core material was determined to be of greater importance than post material or size. Higher elastic moduli of the posts resulted in lower stresses throughout the tooth.