Alain Arias

Morfometría de Premolares Mandibulares en Radiografías Panorámicas Digitales; Análisis de Curvaturas Radiculares

El objetivo de este trabajo fue describir el grado y orientacion de la curvatura radicular en premolares mandibulares, e identificar el tercio radicular en el que la curvatura se origina, mediante el uso de radiografias panoramicas y morfometria lineal. Tambien se detecto la prevalencia de curvaturas radiculares excesivas o dilaceraciones. Se desarrollo un estudio de corte transversal y la muestra consistio en 477 radiografias panoramicas digitales tomadas durante el ano 2014 en un centro radiografico universitario. Se aplicaron criterios de exclusion tanto para radiografias como para los dientes y de esta manera se incorporaron al estudio 118 radiografias (76 mujeres y 42 hombres) y un total de 294 premolares. A partir del analisis de las muestras, se registro el grado y orientacion de curvaturas (mesial o distal), el tercio radicular en el que la curvatura se origino y la prevalencia de dilaceraciones. De los dientes curvados, el angulo promedio de la curvatura fue de 19,68°. Se encontro que 12,24% de los premolares tienen curvatura con orientacion mesial, 58,84% tienen orientacion distal y 28,92% son rectos. Del total de curvaturas, el 0,48% se originaron en el tercio cervical, 27,27% en el tercio medio y 72,25% en el tercio apical. Una asociacion estadisticamente significativa fue encontrada entre el tipo de diente y la orientacion de la curvatura (p= 0,025) y entre el tercio del diente en que se origino la curvatura y la orientacion de esta (p= 0,000). Respecto a los premolares mandibulares, tienen curvaturas radiculares en el 72,09% (angulo promedio: 13,9°). La mayoria de las curvaturas se originaron en el tercio apical (72,25%). La prevalencia de las dilaceraciones fue de 0% o 30,27%, segun distintos criterios. A partir de los resultados obtenidos en nuestra investigacion consideramos que el conocimiento de la anatomia radicular de los dientes es de importancia antes de la ejecucion de procedimientos en endodoncia, ortodoncia y otras areas, para realizar una planificacion adecuada de estas practicas odontologicas.

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).

Application of 3D Electromagnetic Articulography in Dentistry: Mastication and Deglutition Analysis. Protocol Report

The Stomatognathic System (SS) is an integrated and coordinated morphofunctional unit, consisting of skeletal, muscular, angiological, nervous, glandular and dental structures that work in harmony to perform different functions such as chewing, swallowing, speaking, breathing, tasting and esthetics. The study of SS physiology is crucial to achieving a correct maintenance of its normal function or restoration. Thus, we developed a protocol to record mandibular movement, chewing and swallowing (saliva and water) by using the 3D-electromagnetic articulograph AG501 at the Oral Physiology Laboratory of the Research Centre for Dental Sciences (CICO). This tool has been used for decades in speech and phonetic research and it is able to record, present and evaluate articulated structure movement data in real time. The articulograph provides an ordered data matrix (values for the x, y, z axes, among others) for the recorded movement, which is stored in binary files that can be processed by different software. One of these is MATLAB, allowing us to perform a quick, clear and understandable analysis. The existence of a standardized methodology for recording allows an accurate description of the stages to perform different types of measurements according to the researcher’s objective. This has opened the way for a new type of oral physiology analysis based on study reproducibility, which is considered one of the bases of scientific methodology.

A New Tridimensional Insight into Geometric and Kinematic Characteristics of Masticatory Cycles in Participants with Normal Occlusion

The aim of this study was to analyze the general, geometric, and kinematic characteristics of the masticatory cycles movements in a tridimensional way, using a method developed by our study group to provide a new insight into the analysis of mandibular movements due to advancement in the potential of computational analysis. Ten individuals (20.1 ± 2.69 years), molar class I, without mandibular movement problems participated in this study. The movements of the masticatory cycles, frontal and sagittal mandibular border movements, were recorded using 3D electromagnetic articulography and processed with computational scripts developed by our research group. The number of chewing cycles, frequency (cycles/s), chewing cycle areas/mandibular border movements areas ratios, and the mouth opening and closing speeds on the 3D trajectory of the chewing cycle were compared. The cycles were divided and analyzed in thirds. The masticatory cycles showed high variation among the individuals (21.6 ± 9.4 cycles); the frequency (1.46 ± 0.21 cycles/s) revealed a moderate positive correlation (R = 0.52) with the number of cycles. The frontal area ratios between the cycle area and the mandibular border movement presented higher values in the first third (6.65%) of the masticatory cycles, and the ratios of sagittal areas were higher and more variable (first, 7.67%; second, 8.06%; and third, 10.04%) than the frontal view. The opening and closing mouth speeds were greater in the second third of the masticatory cycles (OS, 57.82 mm/s; CS, 58.34 mm/s) without a significant difference between the opening and closing movements when the same thirds were evaluated. Further studies are necessary to improve the understanding of the masticatory cycles regarding the standardization of parameters and their values.

Mandibular range movement in pediatric patients

Assessing the normal range of manibular movement becomes an indispensable tool for the clinical evaluation of the function of the masticatory system. The aim of this study was to measure the range of mandibular movement in mouth opening, protrusion, and lateral movements in pediatric subjects from the city of Temuco, Chile and to determine their association with age, sex, and height. A cross-sectional study was performed in children aged 6-13, treated in the Teaching-Unit-Dental-Clinic at the Universidad de La Frontera, Temuco-Chile. 54 subjects participated in the study (44.4 % females); girls exhibited an average mouth opening of 51.9 mm and males of 54.8 mm. Averages were 53.5 mm for mouth opening, 11.8 mm for protrusion, 9.9 mm for right laterality, and 10.3 mm for left laterality. A statistically significant difference was found between age groups, opening, and right lateral ranges, as well as a weak to moderate correlation between mouth opening and protrusion, protrusion and right laterality, protrusion and left laterality, right and left laterality, height and mouth opening, and height and right lateral ranges. The results of this study provide specific data and evidence on the importance of evaluating all ranges of mandibular movement, relating them to each other and with variables such as age and height.

Localization of the Mental Foramen Through Digital Panoramic Radiographs in a Chilean Population

The purpose of the current research was to describe the location of mental foramen (MF) through digital panoramic radiographs in a Chilean population sample. A cross sectional study was carried out in which 500 radiographs taken at a univers ity clinic in Temuco, Chile, were analyzed. Exclusion criteria were applied and the radiographs were analyzed by two previously calibrated examiners. The antero-posterior and supero-inferior positions of the MF were established in relation to longitudinal axes of pr emolars and the height of their apices, respectively. The distances from the center of the MF to the inferior margin of the mandible, t he midline and the height of the dental apices were measured. In total, 163 radiographs were analyzed (93 female, 70 male). On both left a nd rig t sides, the MF was most commonly found between the longitudinal axes of premolars (58.49 % and 65.43 %) and below of the apices (94.34 % and 95.68 %), with no significant differences for sex and age. On the right side the mean distance to the inferior mar gin of the mandible (D1) was 11.87 ±1.46 mm; to the midline (D2) it was 24.46 ±2.99 mm and to the height of the apices (D3) it was 5.03 ±8.44 mm. On the left side the same distances were 11.98 ± .62 mm, 25.85 ±2.87 mm and 4.09 ±2.21 mm respectively. In conclusions, the distances measured from the MF to anatomical landmarks are smaller in women, however significant differences were only found for D1 (righ t and left sides) and D3 (left side). D2 was the only distance found to diminish with age (left side).

Prevalence and Morphometric Characteristics of the Mandibular Incisive Canal through Panoramic Radiographs in a Chilean Population

The mandibular incisive canal (MIC) is a continuation of the mandibular canal, anterior to the mental foramen, containing the neurovascular bundle of the teeth in anterior mandibular segment. The aim of this study was to calculate the pre v l nc and analyze the morphometric parameters of MIC in a Chilean population through digital panoramic radiographs. A cross-sectional study was performed using 500 digital panoramic radiographies of adult individuals. The prevalence of MIC was set in different sexes, age groups and proximity to teeth; in addition to the morphometric parameters of length, width (diameter) and distances of MIC to dental element and the mandibular base. General MIC prevalence was 53 % (265 cases), 49.9 % in women and 57 % in men. In the age group s, prevalence was higher in men, MIC was predominantly associated to first premolars (98.2 % women; 90 % men), however a relev ant number (42.6 % women; 55.1 % men) was close to the canines. The MIC length ranged from 2.6 to 18 mm (median 5 to 8 mm), the width of 0.8 to 5.4 mm (median 2 to 3 mm), the distance to other elements from 0.6 to 12 , 5 mm (medians 5 to 7 mm) and the argin of the mandible from 4.1 to 16.7 mm (median 8 to 10 mm). The length decreases in older age groups regardless of sex. Width an d distance the mandibular base was larger in men compared to women.

Systematic Standardized and Individualized Assessment of Masticatory Cycles Using Electromagnetic 3D Articulography and Computer Scripts

Masticatory movements are studied for decades in odontology; a better understanding of them could improve dental treatments. The aim of this study was to describe an innovative, accurate, and systematic method of analyzing masticatory cycles, generating comparable quantitative data. The masticatory cycles of 5 volunteers (Class I, 19 ± 1.7 years) without articular or dental occlusion problems were evaluated using 3D electromagnetic articulography supported by MATLAB software. The method allows the trajectory morphology of the set of chewing cycles to be analyzed from different views and angles. It was also possible to individualize the trajectory of each cycle providing accurate quantitative data, such as number of cycles, cycle areas in frontal view, and the ratio between each cycle area and the frontal mandibular border movement area. There was a moderate negative correlation (−0.61) between the area and the number of cycles: the greater the cycle area, the smaller the number of repetitions. Finally it was possible to evaluate the area of the cycles through time, which did not reveal a standardized behavior. The proposed method provided reproducible, intelligible, and accurate quantitative and graphical data, suggesting that it is promising and may be applied in different clinical situations and treatments.

Radiopacity of alloplastic bone grafts measured with cone beam computed tomography: An analysis in rabbit calvaria

Availability of adequate bone structure for dental implants is still a problem in dentistry. Alloplastic grafts, which promote bone regeneration, are used as bone substitutes in orthopedic and oral surgical procedures. The aim of this study was to evaluate the radiopacity of three different synthetic bone grafts in rabbit calvaria, over 3 months, using cone beam computed tomography (CBCT). Four critical-size defects were made on the calvaria of 11 rabbits. The lesions were classified into three groups according to the alloplastic grafts they received: Osteon® 70/30, Osteon collagen®, and Osteon II® groups. The fourth group received blood clot, and served as a control. The bone samples were collected and analyzed with CBCT after the 1st, 2nd, and 3rd month. One month after surgery, the lesions that received Osteon® 70/30 and Osteon collagen® grafts showed the highest radiopacity compared to the lesions with Osteon II® and blood clot. After the 2nd month, the radiopacity values between the three groups that received the grafts were more similar compared to the group with blood clot. After the 3rd month, the lesions with Osteon® 70/30 graft showed the highest radiopacity values, followed by Osteon collagen® and Osteon II® groups. The group that received blood clot showed the lowest radiopacity values. In conclusion, the grafts used in this study had higher radiopacity values compared to blood clot. Among the grafts used, the Osteon® 70/30 graft showed the highest radiopacity values in the 3-month period.