Three Dimensional Mapping of Texture in Dental Enamel

We have used synchrotron x-ray diffraction to study the crystal orientation in human dental enamel as a function of position within intact tooth sections. Keeping tooth sections intact has allowed us to construct 2D and 3D spatial distribution maps of the magnitude and orientation of texture in dental enamel. We have found that the enamel crystallites are most highly aligned at the expected occlusal points for a maxillary first premolar, and that the texture direction varies spatially in a three dimensional curling arrangement. Our results provide a model for texture in enamel which can aid researchers in developing dental composite materials for fillings and crowns with optimal characteristics for longevity, and will guide clinicians to the best method for drilling into enamel, in order to minimize weakening of remaining tooth structure, during dental restoration procedure

Hybodont sharks of the English Bathonian and Callovian (Middle Jurassic).

Recent bulk sampling and study of museum collections has revealed a high diversity of hybodont sharks from the English Bathonian, with 15 species being recognised. In addition, study of dental and skeletal material from the English Callovian has allowed the diagnosis of a new genus and species, Planohybodus peterboroughensis gen. et sp. nov., allowing the Bathonian species Hybodus grossiconus Agassiz to be referred to Planohybodus. Two additional new genera, Secarodus and Frangerodus, are erected for the Bathonian taxa Hybodus polyprion Agassiz and Strophodus lingualis Woodward, respectively. Egertonodus duffini sp. nov. is described and the diagnosis of Egertonodus based on dental material is discussed. The previously unrecorded Hybodus sp., Parvodus sp., and Lonchidion sp. are recognised but left in open nomenclature. Asteracanthus medius (Owen) is recorded in the British Bathonian for the first time, and the status of Bathonian nominal species of Asteracanthus are assessed. Bathonian hybodonts showed great diversity in trophic ecology and many of the species are specific to particular palaeoenvironments

Photobiomodulation therapy on orthodontic movement: analysis of preliminary studies with a new protocol

This study aimed to investigate the effectiveness of photobiomodulation therapy (PBMT) on the acceleration of orthodontic movements, deriving from its biostimulating and regenerative capacity on soft tissues, consequent to the increase in differentiation, proliferation, and activity of cells that are involved with alveolar bone remodeling. The present randomized controlled trial was conducted on six patients who required extractive orthodontic therapy because their ectopic canines had erupted. A total of eight canines were analyzed, four of which received laser irradiation (i.e., experimental group). Two weeks after the extractions, all canines of the experimental and placebo groups were distalized simultaneously and symmetrically with the laceback retraction technique. The PBMT protocol consisted of four cycles of laser applications, one each on days 0, 3, 7, and 14 of the study, with session treatment durations of 2-4 min. The results of the descriptive analysis on the distal displacement speed of the canines after 1 month of follow-up indicate an average displacement of 1.35 mm for the non-irradiated group and 1.98 mm for the irradiated group. Through inferential analysis, a statistically significant difference (p < 0.05) was found between the average speed of the irradiated canines and the control canines. The low energy density laser used in this study, with the parameters set, was found to be a tool capable of statistically significantly accelerating the distal displacement of canines

Treatment Rate Of Second Mesio-Buccal Canals In Maxillary Molars In A Musod Endodontic Resident Patient Population

Purpose: The primary reason for non-surgical root canal treatment (NSRCT) failure in an upper molar is inadequate cleaning, shaping and filling of the second mesio-buccal root canal (MB2). Failure to locate and treat a present MB2 will lead to a worsened long-term prognosis. This retrospective study investigated the treatment rate of MB2s in a sample of patients who were treated in Marquette University School of Dentistry\u27s (MUSOD) advanced dental education program in Endodontics. Materials and Methods: The study protocol was approved by Marquette\u27s IRB. Data were gathered from records of 447 patients who received endodontic treatment between 2008 and 2012 and include; presence of an MB2 (dependent variable), tooth number, patient age (years), and gender (independent variables). Personal identifiers subject to HIPAA regulations were not collected. Presence of an MB2 was determined from clinical notes and verified radiographically. Frequencies of present or absent MB2s were tabulated as a function of various independent variables and statistically analyzed using chi-square tests. Results: Overall, 50.3% of all patients presented with an MB2. Male and female patients had MB2s in 60.6% and 43.8%, respectively. MB2s were found in 53.1% (172 out of 324) and 43.1% (53 out of 123) of maxillary first and second molars, respectively. The mean age of the sample was 42.4 years. Below the mean age, MB2 canals were found in 56.0%, while above the mean age, they were present in 43.2%. There was no statistically significant difference in side distribution (left side of maxillary arch compared to right side). Respective frequencies were 49.3% and 51.4%. Conclusion: MB2 treatment rates may serve as a guide for practicing endodontists because they were achieved with the most current treatment techniques, advanced visualization, adequate time, and clinical expertise

New insights on Anthracotherium monsvialense De Zigno, 1888 (Mammalia, Cetartiodactyla) from the lower Oligocene of Monteviale (Vicenza, northeastern Italy)

In Italy, anthracotheres are represented by a few fossils, most of them described during the XIX century and without a standardized scientific method. Anthracotherium monsvialense De Zigno, 1888 was originally erected from a fossil discovered in the site of Monteviale (Vicenza, northeastern Italy), whose Rupelian (MP21) lignitic beds yielded the richest lower Oligocene evidence of the genus Anthracotherium in Europe. A. monsvialense ranges from MP21 to MP23 and its small size has been interpreted as a consequence of the insular environment, at least at Monteviale. In this study, we summarize the long history of Italian findings providing new descriptions of dental and postcranial morphological features of A. monsvialense, and comparing such small anthracothere with its Asian and European relatives. Morphometric analyses are also performed on teeth, in order to verify the presence of evolutionary trends of the genus Anthracotherium

Quantification of the Individual Characterstics of the Human Dentition: Methodology

This study provides a method for comparing six individual human dentition characteristics using the standard measuring tool in Adobe Photoshop CS2 as compared to measuring individual characteristics with an automated software program under development at Marquette University, which has been adapted for bitemark analysis. The algorithm identifies color-specific pixels and automatically calculates the measurements

In vitro detection of mesio-buccal canals in maxillary molar cross-sections using three different resolutions with Kodak 9000 3D CBCT.

CBCT in endodontics demonstrates anatomic features in 3D that intraoral, panoramic, and cephalometric images cannot. CBCT units reconstruct the projection data to provide interrelational images in three orthogonal planes (axial, sagittal, and coronal). In addition because reconstruction of CBCT data is performed natively using a personal computer, data can be reoriented in their true spatial relationships. Aims: To investigate accurate detection of the correct number of root canals in the mesio-buccal root of the maxillary molar teeth using 3D imaging with cone beam computed tomography (CBCT) at different spatial resolution (isotropic voxel) settings. Methods: With IRB approval, 31 extracted maxillary molars were examined using high resolution, small field of view CBCT at isotropic voxel resolutions ranging at 0.076, 0.10 and 0.20 mm. The image data sets were imported into third party segmentation software to provide 3D videos for 8 observers to determine the number of mesio-buccal root canals in cross-sectional reconstructions. The ground truth was later established by sectioning the tooth roots axially. Results: Twenty-four of the teeth proved on sectioning to have two mesio-buccal canals whereas the others had one canal. Accuracy in detection of mesio-buccal canals varied between observers from 59% to 75% and statistically unrelated to observer experience. No statistical differences were found between the reconstructed 3D images regarding accurate detection of canals. Conclusions: CBCT outperformed the findings for accuracy in detection of mesio-buccal root canals in all previous studies using 2D imaging modalities and Tuned Aperture Computed Tomography. Keywords: Computed Tomography, X-ray, Cone-Beam; Endodontics; Image processing

Sensibilidad de la tomografía computarizada Cone Beam en la identificación de un segundo conducto mesio vestibular permeable en primeros y segundos molares superiores permanentes

Tesis (Cirujano Dentista)Objetivo: El objetivo de este estudio fue determinar la sensibilidad de la Tomografía Computarizada Cone Beam (CBCT) en la identificación de un segundo conducto mesio vestibular permeable en primeros y segundos molares maxilares permanentes. Metodología: Se realizó un análisis radiográfico con Tomografía Computarizada Cone Beam (Accuitomo de Morita) a 42 primeros y segundos molares maxilares permanentes previamente extraídos. Mediante el software “OneVolumeViewer” se determinó la presencia o ausencia de un segundo conducto mesio vestibular (MV2). Posteriormente se realizó el corte transversal de sus coronas a nivel del límite amelo cementario y se observaron bajo microscopio endodóntico determinando la presencia o ausencia de un MV2. En aquellas muestras en las que fue observado un MV2 se determinó la permeabilidad de estos mediante lima N°8. Resultados: El CBCT identificó que 33 dientes presentaban MV2 (78,6%), mientras que el análisis con microscopio óptico identificó 37 conductos MV2 (88.1%). De los 37 conductos MV2 encontrados bajo microscopio se logró permeabilizar 35 de ellos (94.6%). La sensibilidad del CBCT para la identificación de un conducto MV2 fue de un 86,5% y la especificidad de un 80%. En cuanto a la determinación de permeabilidad del MV2 el CBCT presentó una sensibilidad de un 85,7%, y especificidad de un 57.1%. Conclusiones: El CBCT es una herramienta sensible y específica para la identificación de un segundo conducto mesio vestibular. Sin embargo, para la identificación de un segundo conducto MV permeable el CBCT resultó ser un instrumento sensible pero no específico

Tooth Size Comparison Between Citizens of the Chickasaw Nation and Caucasians

Objective The goal of this study is to establish normative tooth crown size (mesio-distal width) data for the Chickasaw Nation and demonstrate how it relates to Caucasian standards. Background: Tooth size ratios represent a diagnostic tool that allow for a prediction of treatment outcomes. A proper relationship of the total mesio-distal width of the maxillary dentition to the mesio- distal width of the mandibular dentition will favor an ideal post treatment occlusion. If a patient has a significant tooth size discrepancy between the dental arches, alignment of the teeth into this ideal occlusion may not be possible. Patients commonly receive orthodontic treatment to correct a malocclusion, and upon initiating treatment, goals are set to an ideal standard established for a patient population. Evaluation of the historical data reveals that there is little detailed knowledge, with no ideal or normative standards, for certain patient populations. This is a current issue presented to members of many Native American tribes across the country. Dentally, Native Americans have been classified as having broader faces and larger dentition than Caucasians, but there has been little detailed investigation into the field to substantiate these claims. One such population, the Chickasaw Nation of Oklahoma, has no published data regarding dental dimensions or facial proportions. A detailed tooth crown size analysis with published information has been conducted on less than 1% of the 562 federally recognized tribes in the United States. Moreover, measurement and examination of tooth crown sizes of the Chickasaw Nation tribe of Native Americans has not been attempted and normative tooth size data does not exist. Methods: We conducted a study on a random sample of 63 pairs of study models from citizens of the Chickasaw Nation of Oklahoma to determine the normative data for citizens of this tribe. All participants had a registered, certified degree of Indian blood quantum. The mesio-distal tooth crown widths were measured to determine standard values for each tooth and the segments needed for analyzing the anterior and overall Bolton ratios. In addition, the maxillary and mandibular intercanine widths were recorded. The measurements were compared to data from Caucasian adolescents in the Iowa Facial Growth Study to determine if there were significant differences in tooth crown widths or Boltonratios between the two patient samples. Results: The initial measurements of the Chickasaw Nation Sample dentition enabled the establishment of standard mesio-distal tooth widths and intercanine distances of tribal citizens. Comparison of the male and female dentition demonstrated males have significantly larger mesio-distal tooth widths. Comparison of left vs. right side like teeth in the Chickasaw dentition demonstrated significant differences in males and females. Evaluation of the male and female Chickasaw dentition vs. the Caucasian normative values demonstrated the Chickasaw dentition was significantly wider. A significant difference was also found in the Bolton ratios of the Chickasaw Nation Sample vs. the Caucasian standard ratios, but the ratios fell within normal limits. Conclusions: Establishment of standard mesio-distal tooth widths and Bolton ratios for the Chickasaw Nation of Oklahoma has demonstrated that there is a significant difference in the tooth widths for male and female citizens of the tribe. In addition, there is a significant difference between the established Chickasaw values and the Caucasian normative values. The results indicate that the mesio-distal crown diameters and tooth segment diameters were consistently larger in the Chickasaw sample. The newly established standards for the Chickasaw Nation will contribute directly to correct diagnosis and treatment planning of the Chickasaw Nation patient population