Does Q-MIX pretreatment improve the dentin bond durability of a two-step self-etch adhesive?

This study aims to analyze and assess the effects of three particular dentin pretreatment solutions on the bond durability of a two-step self-etch adhesive (Optibond XTR) applied to dentin after ageing for 2 years. Thirty-five third molars which were extracted (n = 5 for µTBS, n = 2 for nanoleakage) were divided into five groups: Group 1:Control (no pretreatment), Group 2:17% EDTA, Group 3:2% CHX, Group 4:17% EDTA plus 2% CHX, Group 5: Q-Mix. After the pretreatments of dentin, the dentin adhesive was applied as per the guidelines provided by the manufacturer. Half of the specimens were subjected to µTBS tests for 24 hr, while the remaining half were subjected to the tests after being kept for 2 years in water storage. Also, nanoleakage was evaluated with FE-SEM by examining silver nitrate deposits. The data obtained were evaluated using a two-way analysis of variance and Tukey Post Hoc test. The dentin pretreatments did not affect the 24 hr and 2 years µTBS values for OptiBond XTR. At 24 hr, the EDTA + CHX group (50.3 ± 4.9) showed that the highest µTBS value was obtained. Water ageing significantly reduced the µTBS results and after 2 years the highest µTBS value was obtained from the Q-Mix group (37.7 ± 5.2). Different dentin pretreatments do not alter the 24-hr µTBS and were not able to preserve the bond strength after 2 years of ageing. Q-Mix was able to slow down the regression in the strength of the dentin bond as well as nanoleakage over time.

Effect of QMix 2in1 on sealer penetration into the dentinal tubules.

INTRODUCTION: The purpose of this study was to evaluate the effect of final irrigation with a new endodontic irrigant, QMix 2in1 (Dentsply Tulsa Dental, Tulsa, OK), on sealer penetration into dentinal tubules using confocal laser scanning microscopy. METHODS: Thirty recently extracted human maxillary incisors were used in the present study. The teeth were instrumented with sodium hypochlorite (NaOCl) irrigation and then divided into 3 groups according to the final irrigation regimen used: (1) control group, 2.5% NaOCl; (2) EDTA + CHX group, 17% (EDTA) followed by 2% chlorhexidine (CHX); and (3) QMix group, QMix 2in1. All teeth were dried and then obturated with gutta-percha and rhodamine B-labeled AH26 sealer (Dentsply DeTrey, Konstanz, Germany). After setting, the roots were sectioned horizontally 3, 5, and 8 mm from the root apex. Sealer penetration into the dentinal tubules was examined by confocal laser scanning microscopy. RESULTS: In the apical sections of the roots, no significant difference was detected in the percentage of sealer penetration between any of the final irrigation groups (P > .05). Both the EDTA + CHX and QMix groups showed significantly more sealer penetration than the control group in the middle and coronal sections. However, no difference was found between the EDTA + CHX and QMix groups in either of these areas (P > .05) CONCLUSIONS: Use of EDTA + CHX or QMix during final irrigation significantly improved sealer penetration when compared with the control group in the middle and coronal sections of the roots; however, no effect was observed in the apical sections.

Comparison of sealer penetration using the EndoVac irrigation system and conventional needle root canal irrigation.

INTRODUCTION: The aim of this study was to compare the effect of the EndoVac irrigation system (SybronEndo, Orange, CA) and conventional endodontic needle irrigation on sealer penetration into dentinal tubules. METHODS: Forty single-rooted, recently extracted human maxillary central incisors were randomly divided into 2 groups according to the irrigation technique used: conventional endodontic needle irrigation and EndoVac irrigation. All teeth were instrumented using the ProFile rotary system (Dentsply Maillefer, Ballaigues, Switzerland) and obturated with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) labeled with fluorescent dye. Transverse sections at 1, 3, and 5 mm from the root apex were examined using confocal laser scanning microscopy. The total percentage and maximum depth of sealer penetration were then measured. RESULTS: Mann-Whitney test results showed that EndoVac irrigation resulted in a significantly higher percentage of sealer penetration than conventional irrigation at both the 1- and 3-mm levels (P < .05). However, no difference was found at the 5-mm level. The 5-mm sections in each group showed a significantly higher percentage and maximum depth of sealer penetration than did the 1- and 3-mm sections (P < .05). CONCLUSIONS: The EndoVac irrigation system significantly improved the sealer penetration at the 1- to 3-mm level over that of conventional endodontic needle irrigation.

Effect of working length measurement by electronic apex locator or digital radiography on postoperative pain: a randomized clinical trial.

INTRODUCTION: The aim of this study was to evaluate the effect of working length determination methods, electronic apex locator and digital radiography, on postoperative pain. METHODS: Two hundred twenty patients with asymptomatic single-rooted vital teeth were randomly assigned to 2 groups according to the method used for working length determination, the radiographic group and the electronic apex locator group. After working length determination, chemomechanical preparation was performed in a crown-down technique with ProTaper instruments. A master cone radiograph was taken. Canals were obturated with gutta-percha and sealer by using a lateral compaction technique. Postoperative pain was assessed after 4, 6, 12, 24, and 48 hours by using a 4-point pain intensity scale. In addition, patients were asked to record the number of days necessary to achieve complete pain resolution. RESULTS: Postoperative pain during the 4-hour to 48-hour interval studied was not significantly different (P > .05) between groups. The mean times for pain dissipation in the radiographic and electronic apex locator groups were 3.37 ± 2.79 and 3.88 ± 3.34 days, respectively. The difference between groups was not statistically significant (P > .05). CONCLUSIONS: There is no difference in postoperative pain between working length measurement methods by using an electronic apex locator or digital radiography. The reduced exposure to radiation by using apex locator may be a factor that influences a dentist's decision to choose the electronic apex locator over radiography.

Effect of different final irrigation solutions on dentinal tubule penetration depth and percentage of root canal sealer.

INTRODUCTION: The purpose of this study was to evaluate the effects of different solutions used for final irrigation on sealer penetration into dentinal tubules. METHODS: Thirty-two recently extracted human mandibular premolar teeth were treated with sodium hypochlorite (NaOCl) irrigation. The samples were divided into 4 groups according to the final irrigation solution used: (1) the EDTA group: 17% EDTA + 2.5% NaOCl, (2) the maleic acid (MA) group: 7% MA + 2.5% NaOCl, (3) the citric acid (CA) group: 10% CA + 2.5% NaOCl, and (4) the control group: 2.5% NaOCl. All teeth were obturated using the cold lateral condensation technique with gutta-percha and AH 26 sealer (Dentsply; DeTrey, Konstanz, Germany) labeled with fluorescent dye. The teeth were sectioned at distances of 2, 5, and 8 mm from the root apex. Total percentage and maximum depth of sealer penetration were measured using confocal laser scanning microscopy. RESULTS: The Kruskal-Wallis analysis results showed that there was a significant difference in the percentage and maximum depth of sealer penetration among all groups in all sections (P < .05).The coronal sections in each group showed a significantly higher percentage and maximum depth of sealer penetration than did the apical and middle sections (P < .05). CONCLUSIONS: Final irrigation with EDTA, MA, and CA after the use of NaOCl affected sealer penetration. However, there was no significant difference between these experimental groups (EDTA, MA, and CA) in all sections.

Inhibition of cell survival, viability and proliferation by dentin adhesives after direct and indirect exposure in vitro.

OBJECTIVES: The influence of dentin adhesive systems (Scotchbond Multi-Purpose, XP Bond, Xeno V, Clearfil Protect Bond, AdheSE) on cell survival, viability and proliferation was characterized after direct and indirect exposure using different cell culture techniques. MATERIALS AND METHODS: The primers and cured bonding parts were directly exposed to cells using cell culture inserts, and complete materials were analyzed in a dentin barrier test. Cell responses were examined in 3T3 mouse fibroblasts after 24- and 72-h exposure periods by the estimation of total cell numbers (survival), apoptosis (viability) and cell proliferation. RESULTS: Cell numbers were effectively reduced by the primers of AdheSE, Protect Bond, and Scotchbond Multi-Purpose as well as XP bond after direct exposure in a cell culture insert test device. Likewise, Scotchbond Multi-Purpose primer induced a rate of apoptosis (93.9%) even higher than detected with Protect Bond primer (91.6%). Cell proliferation was entirely inhibited by primers and by Xp Bond as well. The Scotchbond Multi-Purpose was most cytotoxic in a dentin barrier test device after a 24-h indirect exposure. It also increased the percentage of cells in apoptosis to 15.4% compared to untreated controls. CONCLUSION: Unpolymerized primers of dentin adhesives were more cytotoxic than polymerized bonding counterparts. Moreover, total etch dentin adhesives were more cytotoxic than self-etch adhesives. CLINICAL RELEVANCE: When dentin adhesives are used in deep cavities without a protective dentin barrier the leachable hydrophobic and hydrophilic component of dentin adhesive systems can penetrate to the pulp and may induce cytotoxic responses in pulp tissues.