Variables Affecting Measurements of Vertical Occlusal Force

Previous studies of occlusal force have provided conflicting results. The purpose of these studies was to determine whether the extent of vertical opening, contralateral occlusal support, or head posture influenced vertical occlusal forces during swallowing, simulated chewing, and maximum biting effort. Three samples of subjects with normal vertical facial proportions - one each of children, adolescents, and young adults - were evaluated to determine the effects of changes in small (2.5 vs. 6.0 mm) vertical separation of the first molars. A sample of young adults was used to evaluate changes in large (10-40 mm) vertical openings, and a sample of adolescents was used to investigate the effect of contralateral support and head posture. All between-group comparisons were evaluated using non-parametric statistics. For the small vertical openings, there was significantly more vertical occlusal force at 6.0 than 2.5 mm in children during swallowing and chewing but not during maximum biting effort. In adults, there was significantly more force during swallowing at 6.0 than at 2.5 mm separation, but no differences in chewing or maximum biting. Increasingly large vertical openings resulted in a progressive increase in maximum bite force to a maximum at about 20 mm, followed by a decrease and then a second increase to near-maximum force at about 40 mm for young adults. There were no significant differences in vertical force with or without contralateral support or between flexed, normal, and extended head postures at either of the small openings.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68036/2/10.1177_00220345860650020901.pd

Post-extraction mesio-distal gap reduction assessment by confocal laser scanning microscopy - a clinical 3-month follow-up study

[EN] AimThe aim of this 3-month follow-up study is to quantify the reduction in the mesio-distal gap dimension (MDGD) that occurs after tooth extraction through image analysis of three-dimensional images obtained with the confocal laser scanning microscopy (CLSM) technique. Materials and MethodsFollowing tooth extraction, impressions of 79 patients 1month and 72 patients 3months after tooth extraction were obtained. Cast models were processed by CLSM, and MDGD changes between time points were measured. ResultsThe mean mesio-distal gap reduction 1month after tooth extraction was 343.4m and 3months after tooth extraction was 672.3m. The daily mean gap reduction rate during the first term (between baseline and 1month post-extraction measurements) was 10.3m/day and during the second term (between 1 and 3months) was 5.4m/day. ConclusionsThe mesio-distal gap reduction is higher during the first month following the extraction and continues in time, but to a lesser extent. When the inter-dental contacts were absent, the mesio-distal gap reduction is lower. When a molar tooth is extracted or the distal tooth to the edentulous space does not occlude with an antagonist, the mesio-distal gap reduction is larger. The consideration of mesio-distal gap dimension changes can help improve dental treatment planning.The authors would like to express their gratitude to MEC (contract grant number AP2008-01653), to FEDER, to the Generalitat Valenciana for its help in the CLSM acquisition (MY08/ISIRM/S/100), to the Universitat Politecnica de Valencia (PAID-05-12) and to Dr. Asuncion Jaime for her translation assistance.García-Herraiz, A.; Silvestre, FJ.; Leiva García, R.; Crespo Abril, F.; Garcia-Anton, J. (2017). Post-extraction mesio-distal gap reduction assessment by confocal laser scanning microscopy - a clinical 3-month follow-up study. Journal Of Clinical Periodontology. 44(5):548-555. https://doi.org/10.1111/jcpe.12706S548555445Aguilar, M. L., Elias, A., Vizcarrondo, C. E. T., & Psoter, W. J. (2010). Analysis of three-dimensional distortion of two impression materials in the transfer of dental implants. The Journal of Prosthetic Dentistry, 103(4), 202-209. doi:10.1016/s0022-3913(10)60032-7Amit, G., JPS, K., Pankaj, B., Suchinder, S., & Parul, B. (2012). Periodontally accelerated osteogenic orthodontics (PAOO) - a review. Journal of Clinical and Experimental Dentistry, e292-296. doi:10.4317/jced.50822Armitage, G. C. (1999). Development of a Classification System for Periodontal Diseases and Conditions. Annals of Periodontology, 4(1), 1-6. doi:10.1902/annals.1999.4.1.1Belli, R., Pelka, M., Petschelt, A., & Lohbauer, U. (2009). In vitro wear gap formation of self-adhesive resin cements: A CLSM evaluation. Journal of Dentistry, 37(12), 984-993. doi:10.1016/j.jdent.2009.08.006Belli, R., Rahiotis, C., Schubert, E. W., Baratieri, L. N., Petschelt, A., & Lohbauer, U. (2011). Wear and morphology of infiltrated white spot lesions. Journal of Dentistry, 39(5), 376-385. doi:10.1016/j.jdent.2011.02.009Brauchli, L. M., Baumgartner, E.-M., Ball, J., & Wichelhaus, A. (2011). Roughness of enamel surfaces after different bonding and debonding procedures. Journal of Orofacial Orthopedics / Fortschritte der Kieferorthopädie, 72(1), 61-67. doi:10.1007/s00056-010-0002-3Chen, S. Y., Liang, W. M., & Chen, F. N. (2004). Factors affecting the accuracy of elastometric impression materials. Journal of Dentistry, 32(8), 603-609. doi:10.1016/j.jdent.2004.04.002Christou, P., & Kiliaridis, S. (2007). Three-dimensional changes in the position of unopposed molars in adults. The European Journal of Orthodontics, 29(6), 543-549. doi:10.1093/ejo/cjm036Craddock, H. L., Youngson, C. C., Manogue, M., & Blance, A. (2007). Occlusal Changes Following Posterior Tooth Loss in Adults. Part 2. Clinical Parameters Associated with Movement of Teeth Adjacent to the Site of Posterior Tooth Loss. Journal of Prosthodontics, 16(6), 495-501. doi:10.1111/j.1532-849x.2007.00223.xFaria, A. C. L., Rodrigues, R. C. S., Macedo, A. P., Mattos, M. da G. C. de, & Ribeiro, R. F. (2008). Accuracy of stone casts obtained by different impression materials. Brazilian Oral Research, 22(4), 293-298. doi:10.1590/s1806-83242008000400002García-Herraiz, A., Leiva-García, R., Cañigral-Ortiz, A., Silvestre, F. J., & García-Antón, J. (2011). Confocal laser scanning microscopy for the study of the morphological changes of the postextraction sites. Microscopy Research and Technique, 75(4), 513-519. doi:10.1002/jemt.21085Gragg, K. L., Shugars, D. A., Bader, J. D., Elter, J. R., & White, B. A. (2001). Movement of Teeth Adjacent to Posterior Bounded Edentulous Spaces. Journal of Dental Research, 80(11), 2021-2024. doi:10.1177/00220345010800111401LINDSKOG-STOKLAND, B., HANSEN, K., TOMASI, C., HAKEBERG, M., & WENNSTRÖM, J. L. (2011). Changes in molar position associated with missing opposed and/or adjacent tooth: a 12-year study in women. Journal of Oral Rehabilitation, 39(2), 136-143. doi:10.1111/j.1365-2842.2011.02252.xLove, W. D., & Adams, R. L. (1971). Tooth movement into edentulous areas. The Journal of Prosthetic Dentistry, 25(3), 271-278. doi:10.1016/0022-3913(71)90188-0Nishikawa, T., Masuno, K., Mori, M., Tajime, Y., Kakudo, K., & Tanaka, A. (2006). Calcification at the Interface Between Titanium Implants and Bone: Observation With Confocal Laser Scanning Microscopy. Journal of Oral Implantology, 32(5), 211-217. doi:10.1563/799.1Pereira, J. R., Murata, K. Y., Valle, A. L. do, Ghizoni, J. S., & Shiratori, F. K. (2010). Linear dimensional changes in plaster die models using different elastomeric materials. Brazilian Oral Research, 24(3), 336-341. doi:10.1590/s1806-83242010000300013Schilling, T., Müller, M., Minne, H. W., & Ziegler, R. (1998). Influence of Inflammation-Mediated Osteopenia on the Regional Acceleratory Phenomenon and the Systemic Acceleratory Phenomenon During Healing of a Bone Defect in the Rat. Calcified Tissue International, 63(2), 160-166. doi:10.1007/s002239900508Scivetti, M., Pilolli, G. P., Corsalini, M., Lucchese, A., & Favia, G. (2007). Confocal laser scanning microscopy of human cementocytes: Analysis of three-dimensional image reconstruction. Annals of Anatomy - Anatomischer Anzeiger, 189(2), 169-174. doi:10.1016/j.aanat.2006.09.009SHUGARS, D. A., BADER, J. D., PHILLIPS, S. W., WHITE, B. A., & BRANTLEY, C. F. (2000). THE CONSEQUENCES OF NOT REPLACING A MISSING POSTERIOR TOOTH. The Journal of the American Dental Association, 131(9), 1317-1323. doi:10.14219/jada.archive.2000.0385Thalmair, T., Fickl, S., Schneider, D., Hinze, M., & Wachtel, H. (2013). Dimensional alterations of extraction sites after different alveolar ridge preservation techniques - a volumetric study. Journal of Clinical Periodontology, 40(7), 721-727. doi:10.1111/jcpe.12111Thongthammachat, S., Moore, B. K., Barco, M. T., Hovijitra, S., Brown, D. T., & Andres, C. J. (2002). Dimensional accuracy of dental casts: Influence of tray material, impression material, and time. Journal of Prosthodontics, 11(2), 98-108. doi:10.1053/jopr.2002.125192Van der Weijden, F., Dell’Acqua, F., & Slot, D. E. (2009). Alveolar bone dimensional changes of post-extraction sockets in humans: a systematic review. Journal of Clinical Periodontology, 36(12), 1048-1058. doi:10.1111/j.1600-051x.2009.01482.xWeinstein, S. (1967). Minimal forces in tooth movement. American Journal of Orthodontics, 53(12), 881-903. doi:10.1016/0002-9416(67)90163-7Windisch, S. I., Jung, R. E., Sailer, I., Studer, S. P., Ender, A., & Hämmerle, C. H. F. (2007). A new optical method to evaluate three-dimensional volume changes of alveolar contours: a methodological in vitro study. 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Intra-oral compartment pressures: a biofunctional model and experimental measurements under different conditions of posture

Oral posture is considered to have a major influence on the development and reoccurrence of malocclusion. A biofunctional model was tested with the null hypotheses that (1) there are no significant differences between pressures during different oral functions and (2) between pressure measurements in different oral compartments in order to substantiate various postural conditions at rest by intra-oral pressure dynamics. Atmospheric pressure monitoring was simultaneously carried out with a digital manometer in the vestibular inter-occlusal space (IOS) and at the palatal vault (sub-palatal space, SPS). Twenty subjects with normal occlusion were evaluated during the open-mouth condition (OC), gently closed lips (semi-open compartment condition, SC), with closed compartments after the generation of a negative pressure (CCN) and swallowing (SW). Pressure curve characteristics were compared between the different measurement phases (OC, SC, CCN, SW) as well as between the two compartments (IOS, SPS) using analysis of variance and Wilcoxon matched-pairs tests adopting a significance level of α = 0.05. Both null hypotheses were rejected. Average pressures (IOS, SPS) in the experimental phases were 0.0, −0.08 (OC); −0.16, −1.0 (SC); −48.79, −81.86 (CCN); and −29.25, −62.51 (SW) mbar. CCN plateau and peak characteristics significantly differed between the two compartments SPS and IOS. These results indicate the formation of two different intra-oral functional anatomical compartments which provide a deeper understanding of orofacial biofunctions and explain previous observations of negative intra-oral pressures at rest

Possible Tomography of the Sun's Magnetic Field with Solar Neutrinos

The data from solar neutrino experiments together with standard solar model predictions are used in order to derive the possible profile of the magnetic field inside the Sun, assuming the existence of a sizeable neutrino magnetic moment and the resonant spin flavour mechanism. The procedure is based on the relationship between resonance location and the energy dependent neutrino suppression, so that a large neutrino suppression at a given energy is taken to be connected to a large magnetic field in a given region of the Sun. In this way it is found that the solar field must undergo a very sharp increase by a factor of at least 6 - 7 over a distance no longer than 7 - 10% of the solar radius, decreasing gradually towards the surface. The range in which this sharp increase occurs is likely to be the bottom of the convective zone. There are also indications in favour of the downward slope being stronger at the start and more moderate on approaching the solar surface. Typical ranges for the magnetic moment are from a few times 10^{-13}\mu_B to its laboratory upper bounds while the mass square difference between neutrino flavours is of order (0.6-1.9) x 10^{-8}eV^2.Comment: Several minor corrections performed, sunspot anticorrelation discussed, references added, 29 pages including 8 figures in PostScrip

Sagittal jaw position in relation to body posture in adult humans – a rasterstereographic study

BACKGROUND: The correlations between the sagittal jaw position and the cranio – cervical inclination are described in literature. Only few studies focus on the sagittal jaw position and the body posture using valid and objective orthopaedic examination methods. The aim of this study was to test the hypothesis that patients with malocclusions reveal significant differences in body posture compared to those without (upper thoracic inclination, kyphotic angle, lordotic angle and lower lumbar inclination). METHODS: Eighty-four healthy adult patients (with a mean age = 25.6 years and ranging from 16.1 to 55.8 years) were examined with informed consent. The orthodontic examination horizontal overjet (distance between upper and lower incisors) was determined by using an orthodontic digital sliding calliper. The subjects were subdivided in respect of the overjet with the following results: 18 revealed a normal overjet (Class I), 38 had an increased overjet (Class II) and 28 had an reversed overjet (Class III). Rasterstereography was used to carry out a three – dimensional back shape analysis. This method is based on photogrammetry. A three-dimensional shape was produced by analysing the distortion of parallel horizontal white light lines projected on the patient's back, followed by mathematical modelling. On the basis of the sagittal profile the upper thoracic inclination, the thoracic angle, the lordotic angle and the pelvic inclination were determined with a reported accuracy of 2.8° and the correlations to the sagittal jaw position were calculated by means of ANOVA, Scheffé and Kruskal-Wallis procedures. RESULTS: Between the different overjet groups, no statistically significant differences or correlations regarding the analysed back shape parameters could be obtained. However, comparing males and females there were statistically significant differences in view of the parameters 'lordotic angle' and 'pelvic inclination'. CONCLUSION: No correlations between overjet and variables of the thoracic, lordotic or the pelvic inclination could be observed

Nature's Swiss Army Knives: Ovipositor Structure Mirrors Ecology in a Multitrophic Fig Wasp Community

Resource partitioning is facilitated by adaptations along niche dimensions that range from morphology to behaviour. The exploitation of hidden resources may require specially adapted morphological or sensory tools for resource location and utilisation. Differences in tool diversity and complexity can determine not only how many species can utilize these hidden resources but also how they do so.The sclerotisation, gross morphology and ultrastructure of the ovipositors of a seven-member community of parasitic wasps comprising of gallers and parasitoids developing within the globular syconia (closed inflorescences) of Ficus racemosa (Moraceae) was investigated. These wasps also differ in their parasitism mode (external versus internal oviposition) and their timing of oviposition into the expanding syconium during its development. The number and diversity of sensilla, as well as ovipositor teeth, increased from internally ovipositing to externally ovipositing species and from gallers to parasitoids. The extent of sclerotisation of the ovipositor tip matched the force required to penetrate the syconium at the time of oviposition of each species. The internally ovipositing pollinator had only one type of sensillum and a single notch on the ovipositor tip. Externally ovipositing species had multiple sensilla types and teeth on their ovipositors. Chemosensilla were most concentrated at ovipositor tips while mechanoreceptors were more widely distributed, facilitating the precise location of hidden hosts in these wasps which lack larval host-seeking behaviour. Ovipositor traits of one parasitoid differed from those of its syntopic galler congeners and clustered with those of parasitoids within a different wasp subfamily. Thus ovipositor tools can show lability based on adaptive necessity, and are not constrained by phylogeny.Ovipositor structure mirrored the increasingly complex trophic ecology and requirements for host accessibility in this parasite community. Ovipositor structure could be a useful surrogate for predicting the biology of parasites in other communities