Incidence of Post-Operative Pain following a Single-Visit Pulpectomy in Primary Molars Employing Adaptive, Rotary, and Manual Instrumentation: A Randomized Clinical Trial.

Background and Objectives. To differentiate the intensity of postoperative pain after primary molar pulpectomy employing manual instrumentation versus two single-file systems with different kinetics (the XP-Endo shaper file with adaptive instrumentation vs. the Kedo-SG blue file with continuous rotation instrumentation). Materials and Methods. This three-arm, single-blind, randomized clinical trial included assessing 75 healthy children between 4 to 9 years who required pulpectomy for primary molars (mandibular first and second). The three groups each had an equal number of children. Children in Group 1 had their teeth instrumented with the XP-endo Shaper, children in Group 2 had their teeth instrumented with the Kedo-SG Blue file, and children in Group 3 had their teeth instrumented manually using K-files. The degree of postoperative pain was measured using a four-point pain scale at 6-, 12-, 24-, 48-, and 72-h following therapy. Each participant's parent received five flashcards with four faces and a word characterizing each face. The data were analyzed using Kruskal-Wallis and chi-square tests. The level of significance was set to 5%. Results. During the follow-up period, there was a significant difference in postoperative pain intensity between the three groups. The XP-endo shaper was associated with considerably decreased post operative at the 6- and 12-h interval followed by Kedo-SG. The highest post-operative discomfort across the groups was related to the patients who underwent manual instrumentation. Conclusion. In comparison to rotary and manual instrumentation, postoperative pain severity was reduced with adaptive instrumentation.

Modern Applications and Innovations of 3D Dental Imaging.

Recent improvements in imaging techniques have profoundly facilitated the diagnosis of pathologies of the maxillofacial district and provided all the information necessary to plan an adequate treatment plan. Three-dimensional (3D) radiographic diagnostic exams, reworked by specific software that allow easy viewing of images and various graphic reworkings, are frequently applied to maxillofacial district for the diagnosis of various pathologies, which, until a few years ago, required several radiographic examinations.1,2.

Influence of shaft length on torsional behavior of endodontic nickel-titanium instruments.

Torsional stresses are one of the most frequent causes of intracanal separation of nickel-titanium endodontic instruments, which represents a great concern of endodontists. For this reason, torsional resistance of rotary instruments has been deeply investigated by determining all parameters that can influenced it, that can be summarized in: (1) Tooth-related factors, (2) Strategy-related factors and (3) Instrument-related factors. This study was conducted to examine the influence of shaft length on torsional resistance of a nickel-titanium rotary instrument and if it should be considered as an Instrument-related factor. With this aim, 120 Twisted Files Adaptive M-L (TFA M-L) NiTi instruments (SybronEndo, Orange, CA, USA) were divided into 6 experimental groups (n = 20), according to instruments length and size: Group 1, 20 TFA M-L1 25/08 23 mm; Group 2, 20 TFA M-L1 25/08 27 mm; Group 3, 20 TFA M-L2 35/06 23 mm; Group 4, 20 TFA M-L2 35/06 27 mm; Group 5, 20 TFA M-L3 50/04 23 mm; and Group 6, 20 TFA M-L3 50/04 27 mm. All instruments were submitted to a static torsional test, blocking each instrument at 3 mm from the tip and rotating it until its fracture. Torque to Fracture (TtF) and fragments length were registered and all data were statistically analyzed. Results showed that Groups 2, 4 and 6 had a higher TtF, respectively, than Groups 1, 3 and 5, which differ from the former just for shaft length. Group 6 showed the highest torsional resistance (1.31 ± 0.08 Ncm), whilst Group 1 the lowest (0.40 ± 0.08 Ncm). According to that, it can be stated that the longer the instrument, the higher the torsional resistance is, proving that shaft length should be considered as an important factor about torsional resistance.

An Update of Possible Radiation-free Imaging Techniques in Dentistry.

Cone-beam computed tomography (CBCT) represents today the most widespread and most used 3D examination in dentistry. It is precise because of its usefulness in orthodontics and orthognathic surgery with large field of view (FOVs); in oral surgery and implantology for the 3D evaluation of bone volumes and proximity to noble structures; and in endodontics for the understanding of the often difficult root canal system anatomy with reduced FOV and greater resolution that this imaging technique, also considering the wide diffusion and availability in dental offices, in addition to the short examination execution times, allows its wide use.1-4.

How to Improve Properties of Nickel-Titanium Rotary Instruments.

In the last decades, the use of nickel-titanium (Ni-Ti) rotary instruments has become the most effective and popular method among endodontists for shaping root canals, even if there are still concerns regarding the increased risks of intracanal breakage or weakening of the instruments.1,2 So manufacturers started to modify the cross-sectional geometrical aspects of the files in order to improve their resistance to torsional and cyclic fatigue. Design is a major feature in determining instruments' properties including cutting efficiency, removal of debris, stresses generated during instrumentation, and the relative resistance to these stresses; however, a perfect design is not existing and any change in design is likely to provide some advantages but also some disadvantages.3,4.

Possible Complications of Endodontic Treatments.

Endodontic treatments tend to have very high successful rates in spite of the fact that they are quite an invasive, difficult procedure, especially in complex anatomies. Some complications can arise during or after a root canal procedure due to poor understanding of the anatomy and iatrogenic errors mainly during instrumentation. While some of these problems can be anticipated, many can never really be predicted.1-3 As a consequence, retreatment has become a well-defined field of knowledge and expertise in endodontics, since most complications can be solved with proper surgical or nonsurgical retreatments.4 Reinfection or persistent infections: Root canal treatment can fail due to a persistent bacterial infections or reinfections. These include inadequate shaping, cleaning, and obturation procedures, poor restorations, and exposure through a fracture. The remedies are dependent on the primary cause of the reinfection and the affected parts. Persistent infection is the major cause of short-term endodontic failures.5.

Diagnostic accuracy of conventional orthodontic radiographic modalities and cone-beam computed tomography for localization of impacted maxillary canine teeth.

BACKGROUND: Orthodontic treatment planning for an impacted canine tooth requires accurate information about its position. The aim of this study was to compare the diagnostic accuracy of two conventional orthodontic radiographic modalities with cone-beam computed tomography (CBCT) for localization of impacted maxillary canine teeth. MATERIALS AND METHODS: Panoramic radiographs, lateral cephalograms, and CBCT scans of 30 patients with unilaterally impacted maxillary canine teeth were retrieved from the archives. Eight expert orthodontists evaluated the parameters related to the location of impacted canine teeth by using panoramic radiographs and lateral cephalograms of patients. After 4 weeks, the same parameters were evaluated on CBCT scans of patients. The diagnostic accuracy of conventional modalities and CBCT was compared with each other and also with the gold standard. RESULTS: The conventional radiographic modalities and CBCT had similar accuracy for assessment of the overall inclination (p = 0.11), apex morphology (p = 0.18), and mesiodistal position of the apex (p = 0.12). CBCT had significantly higher accuracy for determination of incisal tip location (p = 0.001), labiopalatal (p = 0.001) and vertical (p = 0.01) position of the crown tip, minimum bone thickness covering the crown (p = 0.001), and root resorption of the adjacent tooth (p = 0.001). CONCLUSION: The combination of panoramic radiographs and lateral cephalograms was sufficiently accurate to assess some diagnostic parameters such as overall inclination, apex morphology, and mesiodistal apex location of impacted canine teeth.

Endodontic Orthograde Retreatments: Challenges and Solutions.

Endodontic orthograde retreatments are considered one of the possible treatment options in case of post-treatment diseases considering the promising results present in the literature. Despite this, a plethora of articles have been published on this topic, and drawing conclusions could be challenging. For this reason, this review aims to summarize the crucial points on each aspect of non-surgical endodontic retreatments, discussing and comparing the current protocols, techniques, materials, and indications. Taking into consideration data from the literature, in terms of diagnosis, CBCT should be considered the first choice, since it can thoroughly affect the diagnosis and treatment plan. Regarding the procedural phases, some conclusions can be drawn: when present, coronal restoration materials such as crowns, partial prostheses, post, and core should be removed; the use of magnification devices, ultrasonic instruments, and an in-depth interpretation of radiographic images with both 2D and 3D images are strongly recommended during the orifice location; additional protocols such as irrigants activation, ultrasonic cleaning, and rotary or reciprocating instrumentation of treated canals are strongly recommended for filling materials removal and to achieve a high-quality chemo-mechanical disinfection; perforations should be treated as soon as possible, and the material of choice to treat them is the MTA or other calcium-silicate-based repair materials; the presence of ledges does not intrinsically reduce the success rate of RCRts if properly managed; in case of instrument fragments, their removal should be considered as the first treatment option, however many variables should be considered to select the proper technique or consider the option of bypassing.

Effects of maintenance implant therapy with and without periodic removal and decontamination of prosthetic components on inflammatory peri-implant parameters.

This retrospective clinical study compared two different professional maintenance therapy (MT) approaches (with and without periodic removal and decontamination of prosthetic components) on peri-implant inflammatory clinical and biochemical parameters after 5 years of implant function. A retrospective analysis based on patient records was used to assess inflammatory clinical and biochemical parameters around dental implants placed by the same clinician in a private practice. The Plaque Index (PI), peri-implant probing depth (PPD), mucosal recession (REC), bleeding on probing (BOP), and radiographic marginal bone level were determined at baseline and at each follow-up year. Moreover, at the last follow-up visit, the peri-implant intrasulcular levels of active metalloproteinasis 8 (aMMP-8) were also assessed. All participants were under MT with a 6-month recall interval. A total of 92 patients with 132 implants were selected. At the end of the study period, 12 patients with 12 implants were classified as dropouts. The remaining 80 patients and 120 implants were classified into two groups: Group 1 (42 patients, 62 implants) received MT with periodic removal and decontamination of prosthetic components; Group 2 (38 patients, 58 implants) received MT without periodic removal and decontamination of prosthetic components. No statistical differences were found between the groups regarding PI, PPD, and REC. Group 1 presented a statistically significant higher number of sites with BOP (12.4% vs 6.2%). Marginal bone loss was statistically higher in Group 2 than in Group 1 (0.23 ± 0.6 mm vs 0.78 ± 0.3 mm). Intrasulcular levels of aMMP-8 were statistically higher in Group 1 than in Group 2. The supplemental application of periodic removal and decontamination of prosthetic components during MT had a significantly positive effect on the inflammatory status of peri-implant tissues.

Pushout Bond Strength of Root Fillings after Irrigation of Root Canals Utilizing Sodium Hypochlorite, Chlorhexidine, and Homeopathic Mother Tincture (Arnica Montana).

The pushout bond strength of root fillings at radicular dentin was investigated employing NaOCl, CHX, and homoeopathic mother tincture (Arnica montana) as an irrigant. Sixty human permanent single-rooted extracted teeth were decoronated. The root canals were instrumented using Pro taper universal rotary system (Dentsply Tulsa Dental; Tulsa, Oklahoma) and were prepared up to F3 apical size. The roots were then randomly divided into three groups according to irrigation solution (n = 20) according to the final irrigation regimen: Group I: 3 mL 5.25% NaOCl followed by 3 mL Saline (control); Group II: 3 mL Arnica montana (10%, w/v) followed by 3 mL Saline; Group III: 3 mL CHX followed by 3 mL Saline. The canals were dried using paper points. The canals were coated with AH Plus sealer (Dentsply DeTey, Konstaz, Germany) with the aid of a Lentulo spiral (Dentsply DeTey, Konstaz, Germany) and obturated with #F3 gutta-percha. Each root was then horizontally sliced into three slices, labelled coronal, middle, and apical, each measuring 2 mm thick. Furthermore, at a crosshead speed of 2 mm/min, the test was carried out using the universal testing apparatus. The 5.25% NaOCl significantly decreased the bond strength of AH Plus to dentin. Both CHX and Arnica montana were capable of reversing the compromised pushout of AH Plus to NaOCl-treated dentin. After using NaOCl as an irrigant, the danger of diminished binding capacity of AH Plus to root canal walls arises. Final irrigation with Arnica montana and CHX reduces this risk.

Nationwide Trends of Modern Endodontic Practices Related to Working Length, Instrumentation, Magnification, and Obturation: A Comparative Cross-Sectional Survey Comparing Endodontic and Non-Endodontic Specialties Practicing Root Canal Treatment in India.

Aim: The present study was designed to assess trends in contemporary endodontic practice regarding the techniques and materials used in endodontic therapy among dental practitioners from various regions of India. Methods: A cross-sectional questionnaire-based study was conducted amongst dentists who were pursuing postgraduates in endodontics (PG Endo) and other branches (PG-OB), specialists from other branches (MDS-OB) and specialists in endodontics (MDS-Endo) in various dental colleges representing East, West, North, South, and Central zones through an e-survey using Google forms. State-wise postgraduate dental college lists were obtained from the Dental Council of India (DCI) website. Using a multistage cluster random sampling method and considering the unanticipated response rate, emails were sent to 2100. A 29-item close-ended questionnaire, framed according to different aspects of endodontic treatment, was used to record the responses. Results: When the distribution of the groups of dentists was compared, the central zone had the highest number of PG-OB (44.2%) and the lowest number of MDS-Endo (8.4%). The electronic apex locator (EAL) method of working length determination has been reported less among MDS-Endo than MDS-OB. The difference between the usage of various methods for working length determination was significant among the different groups in all the zones. (p < 0.0001) Most MDS-Endo preferred the rotary method of instrumentation over the combination method for different zones. The majority of dental practitioners preferred a combination method of instrumentation. Conclusion: Zone-wise comparisons among dentists showed the majority of general dental practitioners preferred the combination method (radiographs and electronic apex locator) for working length determination. Most MDS-Endo preferred the rotary method of instrumentation over the combination method for different zones. All dental practitioners did not so commonly use magnification in all the zones. The single cone technique was the most opted by dental practitioners of all the zones.

Dentin Thickness of the Danger Zone in the Mesial Roots of the Mandibular Molars: A Cone Beam Computed Tomography Analysis.

BACKGROUND: Mandibular first molars appear to be the most commonly tooth subjected to a root canal treatment, therefore a better understanding of the anatomy critical zones for resistance of this teeth may decrease the treatment's failure rate. So, this study was conducted to evaluate the dentin thickness of the danger zone in mesial roots of mandibular first molars using cone beam computed tomography in an Iranian population. METHODS: In this cross-sectional study, 210 Cone Beam Computed Tomography acquisition of the mandibular first molars were collected from a radiology center in Qazvin. The dentin thickness of the mesial roots (mesiobuccal and mesiolingual canals) was measured from the furcation to 5 mm below. The relationship between the dentin thickness in the danger zone and parameters, like age, gender, placement side, root length, the curvature of the canal, canal type, presence of middle mesial canal, and distance between the orifices of the mesial canals was investigated. Frequency, mean and standard deviation for variables were calculated, and data analysis was done by SPSS using simple and multiple linear regression and Pearson correlation coefficient. Also, two-sample t-test was used to compare mesiobuccal and mesiolingual on two sides. The significant level was also considered at (p < 0.05). RESULTS: The average minimum thickness of danger zone dentin was found to be 0.885 ± 0.259 mm in the mesiobuccal canal and 0.906 ± 0.206 mm in the mesiolingualcanal. Also, the minimum thickness of dentin in the mesiobuccal and mesiolingual canals in the range of 0 to 1 mm from the furcation was more than in other areas. There was no significant relationship between the minimum dentin thickness of the danger zone with gender, placement side, root length, canal type, and mesial canal entrance distance. But with increasing age, the thickness of dentin in the danger zone in the mesiolingualcanal increased significantly (p = 0.008). It was also observed that with the increase in the curvature of the canal, the thickness of the dentin in the danger zone in the mesiobuccal canal decreased (moderately curved (p = 0.008), severely curved (p = 0.046)). In addition, the thickness of the dentin in the mesiobuccal and mesiolingual canal was less in the samples with the middle mesial canal (p = 0.047, 0.044). CONCLUSIONS: Less dentin thickness in the danger zone in the mesial roots of mesiolingual mandibular first molars was seen in younger patients in mesiolingual canal, with a greater degree of canal curvature in the mesiobuccal canal and teeth with a middle mesial canal. Therefore, it is suggested that large taper instruments should be used with more precision to prevent complications.

Upper First and Second Molar Pulp Chamber Endodontic Anatomy Evaluation According to a Recent Classification: A Cone Beam Computed Tomography Study.

(1) The possibility of knowing information about the anatomy in advance, in particular the arrangement of the endodontic system, is crucial for successful treatment and for avoiding complications during endodontic therapy; the aim was to find a correlation between a minimally invasive and less stressful endodontic access on Ni-Ti rotary instruments, but which allows correct vision and identification of anatomical reference points, simplifying the typologies based on the shape of the pulp chamber in coronal three-dimensional exam views. (2) Based on the inclusion criteria, 104 maxillary molars (52 maxillary first molars and 52 maxillary second molars) were included in the study after 26 Cone Beam Computed Tomography (CBCT) acquisitions (from 15 males and 11 females). And linear measurements were taken with the CBCT-dedicated software for subsequent analysis. (3) The results of the present study show data similar to those already published about this topic. Pawar and Singh's simplified classification actually seems to offer a schematic way of classification that includes almost all of the cases that have been analyzed. (4) The use of a diagnostic examination with a wide Field of View (FOV) and low radiation dose represents an exam capable of obtaining a lot of clinical information for endodontic treatment. Nevertheless, the endodontic anatomy of the upper second molar represents a major challenge for the clinician due to its complexity both in canal shape and in ramification.

Future Trends in Endodontics: How Could Materials Increase the Long-Term Outcome of Root Canal Therapies?

The goals of endodontic therapies are the prevention or the elimination of apical periodontitis of endodontic origin, ensuring the stability of results over time in order to avoid the recurrence of the disease and preventing teeth from requiring extraction [...].

An Update on Advanced Diagnostic Imaging in Dentistry.

In recent years, CBCT has proved to be extremely widely used and widespread in dentistry [...].

Mechanical Performance and Metallurgical Characteristics of 5 Different Single-file Reciprocating Instruments: A Comparative In Vitro and Laboratory Study.

INTRODUCTION: Because there are no data regarding an instrument recently introduced on the market (OneRECI; Coltene MicroMega, Besançon, France), the aim of this study was to assess its mechanical and metallurgical properties comparing them with the following widespread reciprocating instruments: Reciproc (VDW, Munich, Germany), Reciproc Blue (VDW), EdgeOne Fire (EdgeEndo, Albuquerque, NM), and WaveOne Gold (Dentsply Maillefer, Ballaigues, Switzerland). METHODS: A total of 65 nickel-titanium files from 5 different reciprocating systems (OneRECI, Reciproc, Reciproc Blue, EdgeOne Fire, and WaveOne Gold) were evaluated throughout a combined mechanical and metallurgical method. Mechanical performances of the selected file were examined by subjecting each specimen to cyclic fatigue and torsional and bending resistance tests, whereas their metallurgical properties were assessed by analyzing the nickel-titanium alloy composition and the phase transformation temperatures through energy-dispersive X-ray spectroscopy and differential scanning calorimetry, respectively. One-way analysis of variance and the post hoc Tukey test were performed with the significance level set to a 95% confidence level. RESULTS: Energy-dispersive X-ray spectroscopy showed a similar alloy composition for all of the tested files, with a nickel percentage of about 52%-53% and a corresponding percentage of titanium of 47%-48%, whereas the differential scanning calorimetry analysis, although it indicated martensitic characteristics for all files, showed differences in terms of phase transformation temperatures. Overall, OneRECI showed the best mechanical performances in terms of cyclic fatigue and torsional resistance (32.95 ± 2.33 seconds and 0.76 ± 0.03 Ncm, respectively) and flexibility (48.4 ± 4.1 g), with statistically significant differences for all tests (P < .05). The Reciproc files showed the worst flexibility and cyclic fatigue resistance (157.2 ± 8.3 g and 9.27 ± 1.18 seconds, respectively), whereas the EdgeOne Fire showed the lowest torsional resistance (0.39 ± 0.12 Ncm), with statistically significant differences (P < .05). CONCLUSIONS: Within the limitations of this study, the recently introduced OneRECI file showed the best mechanical performance in comparison to the tested instruments, with an equiatomic composition of the nickel-titanium alloy and a martensitic behavior.

Mechanical properties and metallurgical features of two similar endodontic rotary instruments with different heat treatments (FireWire™ and Gold).

The aim of this study was to explain the mechanical differences between EdgeTaper Platinum (ETP) and ProTaper Gold (PTG) determining the transition temperatures and the composition of the alloy of ETP, since no data are present in literature. A total of 130 instruments were selected: 65 ETP F2 and 65 PTG F2. 20 instruments per type were submitted to each mechanical tests. The cyclic fatigue and torsional tests were performed at a pre-set temperature of 35 °C ± 1 °C. During the cyclic fatigue test, Time to fracture, number of cycles to fracture (NCF) and the fragment length (FL) were recorded. During the static torsional, Torque to Fracture (TtF) and FL were recorded. The fracture surface of 5 randomly selected fragments from each test was examined through a Scanning Electron Microscopy (SEM) and an EDX analysis was performed. 20 instruments per type were submitted to a bending test The force generated (grams) to bend each was recorded. Recorded data of mechanical and metallurgical tests were statistically analyzed using a one-way analysis of variance (ANOVA) test with significance set to a 95% confidence level. ETP F2 showed a higher cyclic fatigue resistance and bending ability than PTG F2, with a statistically significant difference (p < 0.05). PTG showed a higher torsional resistance with a statistically significant difference (p < 0.05). DSC analysis of 5 samples for each instrument type pointed out that the austenite finish temperature of PTG was higher than the ETP, respectively of 49.99 ± 3.31 (°C) and 38.92 ± 1.75 (°C). EDX analysis confirmed the near-equiatomic composition of the Ni-Ti alloys, with a presence of a third component recognized as rubidium in the ETP samples. ETP showed higher flexibility in comparison with PTG, despite the latter is characterized by a more martensitic characterization. since its Af temperature is higher than the ETP.

Clinical, radiographic, and biochemical evaluation of two-piece versus one-piece single implants with a laser-microgrooved collar surface after 5 years of functional loading.

AIM: To compare the clinical and radiographic conditions and the expression of pro-inflammatory cytokines in peri-implant crevicular fluid (PICF) at two-piece/bone level (TP/BL) versus one-piece/tissue level (OP/TL) single implants with a laser-microgrooved collar after at least 5 years of loading. MATERIALS AND METHODS: In total, 20 single TP/BL implants and 20 contralateral OP/TL implants, both with a laser-microgrooved collar surface, in 20 systemically and periodontally healthy subjects (12 males and 8 females, between the age of 36 and 64 [mean age of 49.7 ± 12.3 years]), were examined. Levels of IL-1ß, IL-1RA, IL-6, IL-8, IL-17, b-FGF, G-CSF, GM-CSF, IFN, MIP-1ß, TNF-α, and VEGF were assessed in PICF using the Bio-Plex 200 Suspension Array System. Plaque index (PI), probing depth (PD), bleeding on probing (BOP), and gingival recession (REC) were recorded. Radiographic crestal bone levels (CBL) were assessed at the mesial and distal aspects of the implant sites. RESULTS: The mean PI, PD, BOP, and REC values had no significant differences in either group. A higher mean value of CBL with statistical difference was detected for TP/BL compared with OP/TL implants. The levels of IL-1ß, IL-6, IL-8, GM-CSF, and MIP-1ß and TNF-α were higher at TP/BL implants than at OP/TL implants. However, only IL-1ß, IL-6, and TNF-α values presented significant differences between the groups. CONCLUSIONS: Although after 5 years of loading single TP/BL and OP/TL implants with a laser-microgrooved collar surface presented similar good clinical conditions, a higher proinflammatory state and higher crestal bone loss were detected for TP/BL implants.

Surgical-anatomical evaluation of mandibular premolars by CBCT among the Italian population.

BACKGROUND: The thorough knowledge of the anatomy of mandibular premolars is an essential factor for a correct approach to endodontic treatment, concerning both non-surgical and surgical treatment. OBJECTIVES: Since there is no data on the Italian population in this context, the aim of this study was to evaluate, from a surgical perspective, the anatomy of mandibular premolars among the Italian population through a cone-beam computed tomography (CBCT) analysis, considering the morphology of their root canals according to Vertucci's classification and the prospect of their apices with regard to the vestibular bone plate and the proximity to the inferior alveolar nerve and the mental foramen as well as to evaluate the most appropriate distance from the apex in the radicular resection (3 mm or 5 mm). MATERIAL AND METHODS: At total of 492 CBCT acquisitions (from 246 males and 246 females) were included retrospectively, evaluating 720 mandibular premolars. Age, gender, the tooth position in relation to the vestibular plate, the number of roots, the tooth length and the root length, the number of canals, the configuration of the root canal system according to Vertucci's criteria, C-shaped canals, the distance from the cementoenamel junction (CEJ) to the canal bifurcation, the number of apical foramina, and the distance from the apex to the inferior alveolar nerve or the mental foramen were evaluated. RESULTS: The study highlighted the frequent anatomic variability of the root canal system. It found the presence of 1 root for first and second premolars in 97% and 99% of cases, of 2 roots in 2.7% and 0.7% of cases, and of 3 roots in 0.3% and 0.3% cases, respectively. In 92% of cases, the mental foramen was located below a second premolar, or between a first premolar and a second premolar; only in 8% of cases, it was located close to a first premolar, but never as close as to a second premolar. CONCLUSIONS: Mandibular premolars show a truly surprising anatomical variability, especially for mandibular first premolars, which therefore requires adequate radiographic planning before providing any endodontic treatment, or especially endodontic retreatment or endodontic surgery. Taking into account proximity to the inferior alveolar nerve and the mental foramen, any surgical approach must be carefully planned. Frequently, a two-dimensional (2D) radiographic examination is not sufficient to fully understand the anatomical variability of these teeth.

Metallurgical Tests in Endodontics: A Narrative Review.

Since there are no reviews of the literature on this theme, the aim of this narrative review is to summarize the metallurgical tests used in endodontics, pointing out their functional use and their pros and cons and giving readers a user-friendly guide to serve as an orientation aid in the plethora of metallurgical tests. With this purpose, a literature search for articles published between January 2001 and December 2021 was conducted, using the electronic database PubMed to collect all published articles regarding the metallurgical tests used in endodontics for the evaluation of NiTi rotary instruments. The search was conducted using the following keywords: "metallurgy", "differential scanning calorimetry" (DSC), "X-ray diffraction" (XRD), "atomic force microscopy" (AFM), "energy-dispersive X-ray spectroscopy" (EDS), "focused ion beam analysis" (FIB) and "Auger electron spectroscopy" (AES) combined with the term "endodontics" or "NiTi rotary instruments". Considering the inclusion and exclusion criteria, of the 248 articles found, only 81 were included in the narrative review. According to the results, more than 50% of the selected articles were published in one of the two most relevant journals in endodontics: International Endodontic Journal (22.2%) and Journal of Endodontics (29.6%). The most popular metallurgical test was DSC, with 43 related articles, followed by EDS (33 articles), AFM (22 articles) and XRD (21 articles). Few studies were conducted using other tests such as FIB (2 articles), micro-Raman spectroscopy (4 articles), metallographic analysis (7 articles) and Auger electron spectroscopy (2 articles).