EPA Consensus Project Paper: Shifting from the "Analogic Virtual Patient" to the "Digital Virtual Patient" in Prosthodontics. A Scoping Review.

AIMS: To determine whether the use of single or combined mechanical and virtual articulators, as well as facebows, jaw motion trackers, face scanners, and related devices, actually improve the efficacy of the prosthesis obtained in terms of lifespan and patient-related outcomes. To coin the terms Analogic and Digital Virtual Patients (AVP and DVP) as an attempt to analyze, clarify and synthesize terminology and workflows related to previously so-called devices. MATERIALS AND METHODS: A scoping review was accomplished involving different databases. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-ScR) checklist and JBI guidance were followed to extract data regarding the Population, Context and Concept established. RESULTS: Available literature on the efficacy of using devices and techniques related to both AVP and DVP workflows showed arguable study designs, great heterogeneity, and questionable quality. CONCLUSIONS: The terms AVP and DVP have been coined as a first step to clarify and simplify concepts and workflows related to the use of both mechanical and virtual articulators, as well as facebows, or facial and intraoral scanners, among others. This scoping review cannot claim that an AVP approach leads to more effective and efficient prosthetic restorations.

Impact of the coronavirus pandemic on maxillofacial trauma: A retrospective study in southern Spain.

BACKGROUND: The coronavirus pandemic has impacted health systems worldwide, with Spain being one of the most affected countries. However, little is known about the extent to which the effects of staying home, social distancing, and quarantine measures have influenced the epidemiology of patients with maxillofacial trauma. The aim of this study was to analyze the impact of the coronavirus pandemic on the incidence, demographic patterns, and characteristics of maxillofacial fractures in the largest hospital in southern Spain. MATERIAL AND METHODS: Data from patients who underwent surgery for maxillofacial fractures during the first year of the pandemic between 16 March 2020 and 14 March 2021 (pandemic group) were retrospectively compared with a control group during the equivalent period of the previous year (pre-pandemic group). The incidence was compared by weeks and by lockdown periods of the population. Demographic information, aetioloy, fracture characteristics, treatment performed, and days of preoperative stay were evaluated. Descriptive and bivariate statistics were calculated (p<0.05). RESULTS: During the first year of the pandemic, there was a 35.2% reduction in maxillofacial fractures (n=59) compared to the pre-pandemic year (n=91, p=0.040). A significant drop was detected during the total home lockdown period of the population (p=0.028). In the pandemic group, there was a reduction in fractures due to interpersonal aggressions, an increase in panfacial fractures, a significant increase in other non-facial injuries associated with polytrauma (p=0.037), a higher number of open reduction procedures with internal fixation, and a significantly longer mean preoperative stay (p=0.016). CONCLUSIONS: The first pandemic year was associated with a decline in the frequency of maxillofacial trauma and a change in the pattern and characteristics of fractures. Inter-annual epidemiological knowledge of maxillofacial fractures may be useful for more efficient planning of resource allocation and surgical practice strategy during future coronavirus outbreaks and population lockdowns.

Machine learning at the interface of structural health monitoring and non-destructive evaluation.

While both non-destructive evaluation (NDE) and structural health monitoring (SHM) share the objective of damage detection and identification in structures, they are distinct in many respects. This paper will discuss the differences and commonalities and consider ultrasonic/guided-wave inspection as a technology at the interface of the two methodologies. It will discuss how data-based/machine learning analysis provides a powerful approach to ultrasonic NDE/SHM in terms of the available algorithms, and more generally, how different techniques can accommodate the very substantial quantities of data that are provided by modern monitoring campaigns. Several machine learning methods will be illustrated using case studies of composite structure monitoring and will consider the challenges of high-dimensional feature data available from sensing technologies like autonomous robotic ultrasonic inspection. This article is part of the theme issue 'Advanced electromagnetic non-destructive evaluation and smart monitoring'.

Distal root curvatures in mandibular molars: analysis using digital panoramic X-rays.

BACKGROUND: The aim of this study was to describe the degree of curvature in distal roots in the first and second permanent mandibular molars in a Chilean patient sample. A cross-sectional descriptive study was conducted in which digital panoramic X-rays were analysed. MATERIALS AND METHODS: Examinations of patients under 18 years, with signs of distortion or alteration in the contrast or the presence of pathologies that affected visualisation of the roots and pulp-chamber floor of the teeth to be analysed were excluded. Using the AutoCad software, an angle was drawn to represent the curve of the root in its different thirds, drawing lines inside the root canal from the pulp-chamber floor to the dental apex. Using the classic definition of dilaceration (root curvature > 90°), its prevalence was established. 412 teeth and roots were analysed, finding a dilaceration prevalence of 0.73% (n = 3). 84.72% of the roots presented some type of curvature. RESULTS: The middle third had the highest percentage of curvatures and the greatest average of angular curvature, whereas the cervical third was the straightest. No significant differences were found between the degree of curvature and the gender of the subjects, except for the apical third of tooth 3.6. The analysis of curvature by root third offers to the clinician a better perspective of the directional change of the roots and does not limit it to just the presence of curves in the apical third. CONCLUSIONS: The report of the angular degree of the curvatures, in addition to the prevalence of dilacerations, informs to the clinicians about the likelihood of finding difficulties when treating root canals. (Folia Morphol 2018; 77, 1: 131-137).

Prevalence and morphometric analysis of idiopathic osteosclerosis in a Chilean population.

BACKGROUND: The aim of this study was to analyse the prevalence and morpho-metric parameters of idiopathic osteosclerosis (IO) in a Chilean population. IO is an intraosseous growth of compact, benign, unilocular, non-expandable bone that is referred to as an anatomical variation. MATERIALS AND METHODS: A cross-sectional study was performed using 1000 digital panoramic radiographs of adults in which data on the location (maxillary/ mandibular, right/left hemiarcades), shape, position to the dental apex, and the prevalence of IOs were observed in relation to gender and age. The morphometric parameters evaluated were area, height, width, and the linear distances of the IO up to the midline and at the base of the mandible. RESULTS: The overall prevalence was 2.8% (27 individuals), with the majority of cases in women (66.7%) in the second, third, and fifth decades of life, but without significant differences. All cases were present in the mandible (100%), usually in the left hemiarcade (59.3%), molar (48.2%) and premolar (44.4%) regions; at the height of the dental apices (65.5%), with an irregular shape (40.7%) and round (37%). The area of the IOs was 33.9 ± 20.1 mm2, with a height of 7.7 ± ± 3.1 mm, width of 6.6 ± 3.1 mm, and the distance from the IO to the mandible median line was 26.6 ± 10.7 mm and 9.7 ± 3.7 mm to the mandibular base. CONCLUSIONS: All the data observed corroborate with previous studies; the IO does not present a large difference in the Chilean population evaluated compared to pre-vious studies carried out in other populations. (Folia Morphol 2018; 77, 2: 272-278).

Bilateral bifid mandibular canal: a case report using cone beam computed tomography.

The mandibular canal (MC) originates in the mandibular foramen and runs bilaterally through the mandibular ramus and body, ending in the mental foramen. One of the most common anatomical variations is bifid MC, the configurations of which have been classified into four categories and sub-categories. The prevalence of these variations depends on the imaging method used. Studies carried out in panoramic X-rays and cone beam computed tomography (CBCT) show prevalences varying between 1% and 20%. In this case report we present the finding of a bilateral bifid MC by CBCT examination; we describe its location and morphological characteristics. The variation found was a type 1 bilateral bifid MC, which consists in an accessory canal originating from a single mandibular foramen and extending to the third molar or its immediate surroundings. In this report we discuss the importance of detecting these anatomical variations, as well as their implications in clinical practice.

Shadow prices of emerging pollutants in wastewater treatment plants: Quantification of environmental externalities.

Conventional wastewater treatment plants (WWTPs) are designed to remove mainly the organic matter, nitrogen and phosphorus compounds and suspended solids from wastewater but are not capable of removing chemicals of human origin, such as pharmaceutical and personal care products (PPCPs). The presence of PPCPs in wastewater has environmental effects on the water bodies receiving the WWTP effluents and renders the effluent as unsuitable as a nonconventional water source. Considering PPCPs as non-desirable outputs, the shadow prices methodology has been implemented using the output distance function to measure the environmental benefits of removing five PPCPs (acetaminophen, ibuprofen, naproxen, carbamazepine and trimethoprim) from WWTP effluents discharged to three different ecosystems (wetland, river and sea). Acetaminophen and ibuprofen show the highest shadow prices of the sample for wetland areas. Their values are 128.2 and 11.0 €/mg respectively. These results represent a proxy in monetary terms of the environmental benefit achieved from avoiding the discharge of these PPCPs in wetlands. These results suggest which PPCPs are urgent to remove from wastewater and which ecosystems are most vulnerable to their presence. The findings of this study will be useful for the plant managers in order to make decisions about prioritization in the removal of different pollutants.

Injection in temporomandibular joint of rats. Description of technical protocol.

The development of animal models for research has been very diffused. Osteoarthritis is a joint degenerative pathology that induces cartilage erosion, chondrocyte proliferation and osteophyte formation. The aim of this paper is to present a technical procedure to perform the injection of monosodium iodine acetate in the temporomandibular joints of rats to generate osteoarthritis and to contribute to future research analysis related to pathology progression and proper treatment performance. The use of rat models may be a complex process because of their size, but they can be compared to the human temporomandibular joint due to the similar characteristics and the possibility of performing diagnosis and treatment protocols in order to detect this pathology.

Antiphospholipid antibody-mediated effects in an arterial model of thrombosis are dependent on Toll-like receptor 4.

Patients with antiphospholipid syndrome (APS) produce antiphospholipid antibodies (aPL) and develop vascular thrombosis that may occur in large or small vessels in the arterial or venous beds. On the other hand, many individuals produce aPL and yet never develop thrombotic events. Toll-like receptor 4 (TLR4) appears to be necessary for aPL-mediated prothrombotic effects in venous and microvascular models of thrombosis, but its role in arterial thrombosis has not been studied. Here, we propose that aPL alone are insufficient to cause thrombotic events in an arterial model of APS, and that a concomitant trigger of innate immunity (e.g. TLR4 activation) is required. We show specifically that anti-ß2-glycoprotein I (anti-ß2GPI) antibodies, a subset of aPL, accelerated thrombus formation in C57BL/6 wild-type, but not TLR4-deficient, mice in a ferric chloride-induced carotid artery injury model. These aPL bound to arterial and venous endothelial cells, particularly in the presence of ß2GPI, and to human TLR4 by enzyme-linked immunoassay. Arterial endothelium from aPL-treated mice had enhanced leukocyte adhesion, compared to control IgG-treated mice. In addition, aPL treatment of mice enhanced expression of tissue factor (TF) in leukocytes induced by the TLR4 ligand lipopolysaccharide (LPS). aPL also enhanced LPS-induced TF expression in human leukocytes in vitro. Our findings support a mechanism in which aPL enhance TF expression by leukocytes, as well as augment adhesion of leukocytes to the arterial endothelium. The activation of TLR4 in aPL-positive individuals may be required to trigger thrombotic events.

Delivery of glutamine synthetase gene by baculovirus vectors: a proof of concept for the treatment of acute hyperammonemia.

Hyperammonemia, a condition present in patients with urea cycle disorders (UCDs) or liver diseases, can cause neuropsychiatric complications, which in the worst cases result in brain damage, coma or death. Diverse treatments exist for the treatment of hyperammonemia, but they have limited efficacy, adverse effects and elevated cost. Gene therapy is a promising alternative that is explored here. A baculovirus, termed Bac-GS, containing the glutamine synthetase (GS) gene was constructed for the in vitro and in vivo treatment of hyperammonemia. Transduction of MA104 epithelial or L6 myoblast/myotubes cells with Bac-GS resulted in a high expression of the GS gene, an increase in GS concentration, and a reduction of almost half of exogenously added ammonia. When Bac-GS was tested in an acute hyperammonemia rat model by intramuscularly injecting the rear legs, the concentration of ammonia in blood decreased 351 µM, in comparison with controls. A high GS concentration was detected in gastrocnemius muscles from the rats transduced with Bac-GS. These results show that gene delivery for overexpressing GS in muscle tissue is a promising alternative for the treatment of hyperammonemia in patients with acute or chronic liver diseases and hepatic encephalopathy or UCD.

Tumor necrosis factor haplotype diversity in Mestizo and native populations of Mexico.

The so-called tumor necrosis factor (TNF) block includes the TNFA, lymphotoxin alpha and beta (LTA and LTB) genes with single-nucleotide polymorphisms (SNP) and microsatellites with an allele frequency that exhibits interpopulation variability. To date, no reports have included both SNPs and microsatellites at the TNF block to study Mestizo or Amerindian populations from Mexico. In this study, samples of five Mexican Mestizo populations (Durango, Guadalajara, Monterrey, Puebla, and Tierra Blanca) and four native-Mexican populations (North Lacandonians, South Lacandonians, Tepehuanos, and Yaquis) were genotyped for two SNPs (LTA+252A>G and TNFA-308G>A) and four microsatellites (TNFa, d, e, and f), to analyze the genetic substructure of the Mexican population. Allele and haplotype frequencies, linkage disequilibrium (LD), and interpopulation genetic relationships were calculated. There was significant LD along almost all of the TNF block but the lowest D' values were observed for the TNFf-TNFd pair. Mestizos showed higher allele and haplotype diversity than did natives. The genetic differentiation level was reduced among Mestizos; however, a slightly, but significant genetic substructure was observed between northern and southern Mexican Mestizos. Among the Amerindian populations, the genetic differentiation level was significantly elevated, particularly in both North and South Lacandonians. Furthermore, among Southern Lacandonians, inhabitants of Lacanja town were the most differentiated from all the Mexicans analyzed. The data presented here will serve as a reference for further population and epidemiological studies including these TNF polymorphisms in the Mexican population.

Biochemical evidence for gap junctions and Cx43 expression in immortalized human chondrocyte cell line: a potential model in the study of cell communication in human chondrocytes.

OBJECTIVE: The development of chondrocytic cell lines has enabled the investigation of the role of cellular phenotype and mechanisms in articular cartilage biology and physiopathology of several rheumatic diseases. Among them, the T/C-28a2 cell line has become a common tool in cartilage research. Recent results from our group have revealed that primary human chondrocytes in tissue and in monolayer culture contain high levels of connexin 43 (Cx43) and are able to directly communicate through gap junction (GJ) channels. These results challenge the existing thesis of cartilage physiology, that chondrocytes do not have the capacity to physically communicate with each other. Established cell lines offer the advantage of convenience and uniformity; however, the establishment process may cause a disruption of GJ. This study was performed to investigate if T/C-28a2 cells contain Cx43 protein and form functional channels. METHODS: Cx43 was characterized by RT-qPCR, Western blotting, and immunohistochemistry (IHC). Electrophysiology experiments, Lucifer Yellow (LY) uptake, electroporation in situ and scrape loading assay were performed to test the functionality of GJs. RESULTS: T/C-28a2 cells express Cx43. Electrophysiology experiments and LY uptake confirmed the capacity of these cells to communicate through GJ channels, although these cells contain significant levels of active c-Src kinase, presumably due to their immortalization with the Simian Virus 40 large T antigen. The results were validated using primary chondrocytes (PC). CONCLUSIONS: These results reveal that the T/C-28a2 line may provide a useful in vitro model for the study of Cx43 function and cell communication to understand the physiology of chondrocytes and cartilage.

Differential phase-amplitude coupling in nucleus accumbens and orbitofrontal cortex reflects decision-making during a delay discounting task.

BACKGROUND: The impulsive choice is characterized by the preference for a small immediate reward over a bigger delayed one. The mechanisms underlying impulsive choices are linked to the activity in the Nucleus Accumbens (NAc), the orbitofrontal cortex (OFC), and the dorsolateral striatum (DLS). While the study of functional connectivity between brain areas has been key to understanding a variety of cognitive processes, it remains unclear whether functional connectivity differentiates impulsive-control decisions. METHODS: To study the functional connectivity both between and within NAc, OFC, and DLS during a delay discounting task, we concurrently recorded local field potential in NAc, OFC, and DLS in rats. We then quantified the degree of phase-amplitude coupling (PAC), coherence, and Granger Causality between oscillatory activities in animals exhibiting either a high (HI) or low (LI) tendency for impulsive choices. RESULTS: Our results showed a differential pattern of PAC during decision-making in OFC and NAc, but not in DLS. While theta-gamma PAC in OFC was associated with self-control decisions, a higher delta-gamma PAC in both OFC and NAc biased decisions toward impulsive choices in both HI and LI groups. Furthermore, during the reward event, Granger Causality analysis indicated a stronger NAc➔OFC gamma contribution in the HI group, while the LI group showed a higher OFC➔NAc gamma contribution. CONCLUSIONS: The overactivity in NAc during reward in the HI group suggests that exacerbated contribution of NAcCore can lead to an overvaluation of reward that biases the behavior toward the impulsive choice.

Holographic grating stability: influence of 4,4'-azobis (4-cyanopentanoic acid) on various spatial frequencies.

This paper presents the results obtained when holographic gratings were stored with a spatial frequency of 954 and 2663 lines/mm in transmission geometry and 4600 lines/mm in reflection geometry in a polyvinyl alcohol/acrylamide-based material. Photopolymers are materials that give good results at low frequencies, but their diffraction efficiency (DE) decreases at high frequencies. A chain transfer agent, 4,4'-azobis (4-cyanopentanoic acid) (ACPA) was incorporated in the material composition to improve spatial resolution. Furthermore, a curing process was applied to the stored gratings in order to maintain the DE stable over time. The DE and shrinkage for symmetric holographic transmission and reflection gratings were measured to evaluate their quality and quantify the improvement produced by ACPA.

[Truth telling of Alzheimer's disease diagnosis]. / Comunicación diagnóstica en enfermedad de Alzheimer. Reflexión y propuesta.

Alzheimer's disease is becoming an increasingly common problem due to population aging. Most of the research on truth telling in relation to diagnosis has been done in oncology. However, although growing, there has a lack of interest about attitudes held among physicians towards disclosing the diagnosis of Alzheimer's disease. Physicians, family caregivers and patients have different views about it. The reasons most often given for communicating the diagnosis are the right to know, relief of anxiety to know the cause of memory problems, early access to treatment and ability to plan ahead. On the contrary, the reasons for concealing the diagnosis are based on the right not to know, the anxiety associated to knowing the diagnosis and the absence of curative therapies for the disease. The aim of this paper is to report the current state of literature on diagnostic truth telling in dementia, review the ethical principles involved, and finally give a strategy to address the issue.

[Cognitive impairment associated to primary hyperparathyroidism: report of one case]. / Deterioro cognitivo e hiperparatiroidismo primario: resultado favorable después de cirugía: Caso clínico.

We report a 79-year-old male patient presenting with progressive memory loss associated with anxiety and muscular pain. An extensive biochemical control revealed high serum calcium and parathormone levels, and normal thyroid hormones. Cognitive assessment prior to surgery was compatible with mild cognitive impairment, showing significant improvement two months after parathyroidectomy. Our case suggests that, although rare, primary hyperparathyroidism should be considered as a possible cause of cognitive decline in the elderly.

Prospective evaluation of the time to peak effect of propofol to target the effect site in children.

BACKGROUND: The plasma-effect site equilibration rate constant (k(e0)) of propofol has been determined in children with the use of the time to maximum effect (t(peak)), however, it has not been validated. The objective was to measure the t(peak;) of propofol with two depths of anesthesia monitors in children and to evaluate these measurements with a target-controlled infusion (TCI) system. METHODS: Unpremedicated, ASA I children from 3 to 11 years were studied. In Part 1, children were monitored simultaneously with the bispectral index (BIS) and the A-Line ARX-index (AAI) from the Alaris A-Line auditory-evoked potential monitor/2. The t(peak) after a bolus dose of propofol was measured. In Part 2, the t(peak) measured was used to target the effect site with a TCI system. The median (MD) and the absolute median (MDA) difference between the predicted time of peak concentration at the effect site (Ce) and the measured time of peak effect in the index of depth of anesthesia (t(error)) was used to evaluate the performance of the system. RESULTS: The BIS recordings were of a better quality than the AAI. The mean +/- standard deviation t(peak) was 65 +/- 14 s with the BIS (n=25) and 201 +/- 74 s with the AAI (n=10)(P<0.001). Validation was only performed with the BIS monitor in 40 children, yielding an MD t(error) of -9.5 s and an MDA t(error) of 10.0 s. CONCLUSIONS: The small delay between the evolution of Ce of propofol and the observed effect suggests that this can be a useful model to target the effect site in children.

Do community mental health teams caring for severely mentally ill patients adjust treatments and services based on patients' antisocial or criminal behaviours?

BACKGROUND: Antisocial behaviour is common among patients with severe mental illness (SMI) requiring hospitalisation. AIM: To determine whether differential treatments and services are provided to patients with SMI who engage in antisocial behaviour. METHOD: A random sample of 161 inpatients with SMI were recruited from general adult wards and assessed at baseline and two years later. Information on symptoms, aggressive behaviour, substance misuse, and service use was obtained from patients and clinical files. RESULTS: Past antisocial behaviours were not associated with type or intensity of treatments and services. Severity of positive symptoms, aggressive behaviour, and illicit drug use were positively associated with the frequency of CMHT contact, but not with the type of CMHT, type of medication, or other treatments and benefits. CONCLUSIONS: While the frequency of meetings with CMHTs increased with the severity of antisocial behaviours, no specific treatments were provided to patients with SMI engaging in antisocial behaviours.

Adsorption of glyphosate on variable-charge, volcanic ash-derived soils.

Glyphosate (N-phosphonometylglycine) is widely used due to its broad spectrum of activity and nonselective mode of action. In Chile it is the most used herbicide, but its adsorption behavior in the abundant and widespread variable charge soils is not well understood. In this study, three volcanic ash-derived soils were selected, including Andisols (Nueva Braunau and Diguillin) and Ultisols (Collipulli), to evaluate the adsorption kinetics, equilibrium isotherms, and the effect of pH in glyphosate adsorption. The influence of glyphosate on soil phosphorus retention was also studied. Glyphosate was rapidly and strongly adsorbed on the selected soils, and adsorption isotherms were well described by the Freundlich relationship with strong nonlinearity (n(fads) < 0.5). The n(fads) values were consistently higher than n(fdes) values, suggesting strong hysteresis. Adsorption (K(ads)) increased strongly when pH decreased. The presence of glyphosate (3200 mug mL(-1)) changed the adsorption behavior of phosphate at its maximum adsorption capacity. Andisol soils without the addition of glyphosate had similar mean K(ads) values for Nueva Braunau (5.68) and Diguillin (7.38). Collipulli had a mean K(ads) value of 31.58. During the successive desorption steps, glyphosate at the highest level increased K(ads) values for phosphate in the Andisol soils but had little effect in the Ultisol soil. This different behavior was probably due to the irreversible occupation of some adsorption sites by glyphosate in the Ultisol soil attributed to the dominant Kaolinite mineral. Results from this study suggest that in the two types of volcanic soils, different mechanisms are involved in glyphosate and phosphate adsorption and that long-term use of glyphosate may impose different effects on the retention and availability of phosphorus. Volcanic ash-derived soils have a particular environmental behavior in relation to the retention of organic contaminants, representing an environmental substrate that may become highly polluted over time due to intensive agronomic uses.

Morphological variations of the mandibular canal in digital panoramic radiographs: a retrospective study in a Chilean population.

BACKGROUND: Morphological variations of the mandibular canal (MC) have been described in literature, so the clinician must be able to recognise them and adapt their treatment accordingly. The aim of this study was to determine the prevalence of morphological variations of the MC using digital panoramic radiographs (DPR) of Chilean patients. MATERIALS AND METHODS: A retrospective study in which 1400 DPR were analysed to identify cases of bifid, trifid and retromolar MC. The radiographs were analysed independently by two examiners who had previously been trained by a specialist in oral and maxillofacial radiology. Inclusion and exclusion criteria were applied to reach a final sample. RESULTS: Nine hundred and twenty-five radiographs were included (599 female, 326 male; mean age 36.1 ± 15.54 years). The prevalence of bifid MC was 11% (n = 102), with no significant differences by sex (p = 0.069). Proportion of bifid MC was higher among younger patients (p = 0.038). Prevalence of morphologi- cal variations of type 1 bifid MC was 7.4% (n = 69), type 2 was 2.3% (n = 23), type 3 was 0% (n = 0) and type 4 was 1.1% (n = 10). Prevalence of retromolar canal was 0.9% (n = 8), with no significant differences by sex (p = 0.893) or age (p = 0.371); of these, 2 (0.2%) cases were forward type and 6 (0.6%) cases were retromolar type. No cases of trifid MC were found. CONCLUSIONS: Digital panoramic radiographs are useful for detecting morphological variations of the MC; we were able to identify three types of bifid MC as well as retromolar canals. Proper identification of these variations by an easily accessible examination is important for avoiding possible complications in clinical-surgical practice.