Leopoldo Forner

Review of ultrasonic irrigation in endodontics: increasing action of irrigating solutions

Introduction: Effective irrigant delivery and agitation are prerequisites for successful endodontic treatment. Ultrasonic irrigation can be performed with or without simultaneous ultrasonic instrumentation. Existing literature reveals that ultrasonic irrigation may have a very positive effect on chemical, biological and physical debridement of the root canal system as investigated in many in vitro studies. Objective: The purpose of this review article was to summarize and discuss the available information concerning ultrasonic irrigation in endodontics. Methods: This article presents an overview of ultrasonic irrigation methods and their debridement efficacy. In this paper the relevant literature on passive ultrasonic irrigation is reviewed. Information from original scientific papers or reviews listed in MEDLINE and Cochrane were included in the review. Results: The use of ultrasound in the irrigation procedure results in improved canal cleanliness, better irrigant transfer to the canal system, soft tissue debridement, and removal of smear layer and bacteria. There are many in vitro studies, but there is a need to standardize protocols, and correlate the clinical efficacy of ultrasonic devices with improved treatment outcomes. Understanding the basis of ultrasonic irrigation is fundamental for clinicians and researchers to improve the design and use of ultrasonic irrigation. Key words:Ultrasonic irrigation, ultrasound, smear layer, endodontics.

The Use of Atomic Force Microscopy in Determining the Stiffness and Adhesion Force of Human Dentin After Exposure to Bleaching Agents

INTRODUCTION Oxidant bleaching agents may induce several alterations on mineralized teeth tissues. Our aim is to study, at the ultrastructural level, mechanical modifications induced on dentin after exposure to different bleaching agents. METHODS Nanoindentation performed with atomic force microscopy was used to measure changes in dentin stiffness as well as the adhesion force between the tip and the tissue both in intertubular and peritubular dentin. For each specimen, dentin localization, and bleaching agent, 100 independent nanoindentations were performed. Carbamide peroxide (30%) and hydrogen peroxide (35%) were used as bleaching agents. RESULTS A significant reduction of both stiffness and adhesion force was found for both carbamide and hydrogen peroxide in peritubular and intertubular dentin. CONCLUSIONS The use of bleaching agents led to a significant reduction in dentin local (at the nanoscale) mechanical properties.

Cone-beam computed tomography analysis of root and canal morphology of mandibular premolars in a Spanish population

Purpose This study aimed to investigate the clinical anatomy of lower premolar roots in a Spanish population by using cone-beam computed tomography (CBCT), correlating findings with patient gender and tooth type. Materials and Methods Using 70 CBCT images, we evaluated 126 healthy, untreated, well-developed lower premolars. The number and morphology of roots and root canals, and the foramina number were assessed. Results for gender and tooth type were compared using the chi-squared and ANOVA tests. Results The average length of teeth and roots was significantly higher in men (p=0.00). All 126 premolars had a single root. One canal was found in 83.3% of the premolars, with no gender or tooth type differences; Vertucci configuration types I and V were the most prevalent. The first premolars showed significantly greater variability than the second premolars (p=0.03). A single apical foramen was found in 89.7% of the premolars, with no differences by tooth type. Women had a significantly higher prevalence of two apical foramina than men (p=0.04). Some degree of curvature was observed in 65% of the premolars, with no differences by gender or tooth type. A root angle of more than 20° was found in 12.98% of the premolars, without any differences by gender or tooth. Conclusion All premolars were single-rooted. One canal had the most prevalent morphology. More variability in canal anatomy was found in the first premolars. Curvatures greater than 20° were found at less than 5 mm from the apex.

Oval fiber posts do not improve adaptation to oval-shaped canal walls.

INTRODUCTION Oval fiber posts attempt to provide better adaptation to root canals. The hypothesis of this study was that there are no differences in adaptation of oval and circular fiber posts to canal walls. METHODS Posts were inserted in 20 canals; 10 were oval, and 10 were circular. The posts were cemented with composite cement. Coronal, middle, and apical sections were observed through a microscope. The space occupied by the post and the maximum distance between it and the canal wall were calculated. The 2 groups were compared with analysis of variance. In all the analyses the level of significance was set at P < .05. RESULTS The proportion of space occupied by the post showed no significant differences (P > .05). The cement layer was thinner in the apical region in oval posts (P < .05). CONCLUSIONS Oval posts do not adapt better than circular posts to the morphology of oval canals.

Influence of Operator's Experience on Root Canal Shaping Ability with a Rotary Nickel-Titanium Single-File Reciprocating Motion System

INTRODUCTION The aim of this study was to evaluate the influence of the operators experience on the shaping of double-curvature simulated root canals with a nickel-titanium single-file reciprocating motion system. METHODS Sixty double-curvature root canals simulated in methacrylate blocks were prepared by 10 students without any experience in endodontics and by 10 professionals who had studied endodontics at the postgraduate level. The Reciproc-VDW systems R25 file was used in the root canal preparation. The blocks were photographed before and after the instrumentation, and the time of instrumentation was also evaluated. Changes in root canal dimensions were analyzed in 6 positions. RESULTS Significant differences (P < .05) were found in the apical transport of the first root canal curvature, with a larger percentage of increase of the root canal occurring in the novice group than in the expert one, as well as in the canal deviation at the beginning of the curvatures, whereas no significant results were obtained in the growth rate of the canal area. There was difference in the time of instrumentation, with 3.76 minutes observed in the novice group, as opposed to 2.05 minutes in the expert group. CONCLUSIONS The use of the single-file reciprocating motion system Reciproc is not seen to be influenced by the operators experience regarding the increase of the canal area. Previous training and the need to acquire experience are important in the use of this system, in spite of its apparent simplicity.

Smear layer removal in canals shaped with reciprocating rotary systems

The aim was to assess the presence of smear layer after canal instrumentation with two reciprocating rotary systems and a continuous motion one. Thirty canals were shaped with Reciproc, WaveOne or Mtwo systems. Smear layer was assessed following a three value scale at coronal, middle and apical levels with a scanning electron microscopy. Reciproc scores: coronal third, 20% of the cases: 0, 60%: 1, 20%: 2; middle third, 10%: 0, 20%: 1, 70%:2; apical third: 2 in all cases. WaveOne scores: coronal third, 0 (40%), 1 (30%) and 2 (30%); middle third, 0 (20%), 1 (50%), 2 (30%); apical third, 0 (20%), 2 (80%) of cases. MTwo scores: coronal third 0 (50%), 1 (30%) 2 (20%); middle third 0 (20%), 1 (50%), 2 (30%); apical third, 0 (10%), 1 (10%), 2 (80%). No significant differences (p>0.05) were found between the three used systems. Key words:Endodontics, reciprocating motion files, rotary file, SEM, smear layer.

Fibre post behaviour prediction factors. A review of the literature.

Introduction: The advantages of fibre posts over stainless steel posts have been demonstrated in numerous studies. For clinical success, various factors need to be taken into account in post-retained restorations. Material and Methods: A review was made of literature on fibre posts published from 2000 to February 2011, identified through searches of the PubMed/Medline databases. Results: The position of the tooth in the arch, ferrule size, proximal contact, periodontal support and restoration type are survival prediction factors that should be considered when performing post-endodontic restoration. Since fibre posts present good biomechanical behaviour as a result of their elastic modulus, which is similar to that of dentine, treatment failure occurs through decementation rather than because of root fracture, as occurs with metal posts. The shape of the post and, consequently, the thickness of the luting, can modify the retention capacity. Consequently, more anatomically-shaped posts have been developed, as have new techniques to reduce the volume of the dentine/cement interface: lateral condensation, surface remodelling or custom designs. Conclusions: Different aspects of the preparation process can be modified to assist in improving fibre post retention, but further investigation, mainly clinical, is needed to acquire a better understanding of how different factors influence the long-term clinical behaviour of the posts. Key words:Fiber post, post shape, post adaptation, post retention, endodontics.

Biocompatibility of New Pulp-capping Materials NeoMTA Plus, MTA Repair HP, and Biodentine on Human Dental Pulp Stem Cells

Introduction: The aim of the present study was to evaluate the in vitro cytotoxicity of MTA Repair HP, NeoMTA Plus, and Biodentine, new bioactive materials used for dental pulp capping, on human dental pulp stem cells (hDPSCs). Methods: Biological testing was carried out in vitro on hDPSCs. Cell viability and cell migration assays were performed using eluates of each capping material. To evaluate cell morphology and cell attachment to the different materials, hDPSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy. The chemical composition of the pulp‐capping materials was determined by energy‐dispersive X‐ray and eluates were analyzed by inductively coupled plasma‐mass spectrometry. Statistical differences were assessed by analysis of variance and Tukey test (P < .05). Results: Cell viability was moderate after 24 and 48 hours in the presence of MTA Repair HP and NeoMTA Plus, whereas at 48 and 72 hours, Biodentine showed higher rates of cell viability than MTA Repair HP and NeoMTA Plus (P < .001). A cell migration assay revealed adequate cell migration rates for MTA Repair HP and NeoMTA Plus, both similar to the control group rates, meanwhile the highest cell migration rate was observed in the presence of Biodentine (P < .001). Scanning electron microscope studies showed a high degree of cell proliferation and adhesion on Biodentine disks but moderate rates on MTA Repair HP and NeoMTA Plus disks. Energy‐dispersive X‐ray pointed to similar weight percentages of C, O, and Ca in all 3 materials, whereas other elements such as Al, Si, and S were also found. Conclusions: The new pulp‐capping materials MTA Repair HP, NeoMTA Plus, and Biodentine showed a suitable degree of cytocompatibility with hDPSCs, and good cell migration rates, although Biodentine showed higher rates of proliferation time‐dependent. HighlightsResults of this work suggest that hDPSCs show suitable biological response in terms of cell viability, cell proliferation, and cell migration when in contact with extracts from NeoMTA Plus, MTA Repair HP, and Biodentine.NeoMTA Plus and MTA Repair HP exhibited similar cytocompatibility and cell attachment with hDPSCs, whereas Biodentine promotes higher proliferation rates, cell migration, and cell attachment.Further in vitro and in vivo investigations are required to contrast these results and to prove suitable clinical applications of NeoMTA Plus and MTA Repair HP.

Student evaluation of clickers in a dental pathology course

Background The purpose of this study was to evaluate the degree of satisfaction of students and teachers, and to determine whether the students notice improvements in learning and in the learning environment as a result of the use of clicker. Material and Methods Descriptive study. Fifty-one students and 8 teachers participated in the use of clicker technology in 8 preclinical seminars in dental pathology. Students and teachers filled a three-domain questionnaire at the end of the preclinical course. We used the Mann-Whitney U-test to compare the results between the two groups. Results The domain “perception and expectation” showed the use of clickers to be simple and convenient for 80% of the students, who expressed interest in extending the practice to other teaching areas. In the domain “active learning”, over 70% of the students found the technique to be dynamic, participative and motivating. In the domain “improved learning”, over 70% considered it useful to know their level of knowledge before the seminar and found the contents of the lesson to be clear. Thirty percent considered the items of the examination to be of a complexity similar to that of the first and second tests. Only in this latter aspect were significant differences found between the teachers and students (p=0.001). Conclusions Participants described the use of clickers as simple and useful, motivating and participative. Both the students and teachers considered the technique to improve teaching and the learning environment. Key words:Dental education, audience response system, clickers, classroom response system, student´s perception.

Effectiveness of passive ultrasonic irrigation in improving elimination of smear layer and opening dentinal tubules

Objective: To compare the ability to eliminate debris and open dentinal tubules of different ultrasound irrigation procedures. Study Design: Forty extracted single-rooted human teeth were instrumented with mechanical rotatory instrumentation, and divided into four groups: (n=10) according to the final irrigation technique: group A (control), 2.5% NaOCl irrigation with the Miraject needle and no ultrasonic agitation; group B, passive ultrasonic irrigation (PUI) with 2.5% NaOCl and Irrisafe 20 tips; group C, PUI with 2.5% NaOCl and Irrisafe 25 tips; group D, PUI with 2.5% NaOCl and K 25 tips. The amount of debris and the number of opened dentinal tubules was established by scanning electronic microscope. Data were compared using the Kruskal Wallis test. Results: Irrisafe tips (groups B and C) opened up more dentinal tubules and eliminated more debris than conventional irrigation (p<0.05) in the apical third. The middle third shows no significant differences between groups. Irrisafe 25 was more effective than conventional irrigation and K tips (p<0.05) in the coronal third. Conclusions: Ultrasonic activation of the irrigation with Irrisafe tips was the most effective procedure for eliminating the debris and opening up dentinal tubules, especially in the apical third. Key words:Pasive ultrasonic irrigation, irrigation, sodium hypochlorite.