Browsing by Subject "dental occlusion"

Now showing 1 - 5 of 5
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    The combined effects of salivas and occlusal indicators on occlusal contact forces
    (Wiley, 2019) Beninati, Christopher J.; Katona, Thomas R.; Orthodontics and Oral Facial Genetics, School of Dentistry
    Background Some occlusal detection products are designed for use on dry teeth, but this is not always achieved. Others are suited for dry and wet applications. Objective The objective of this study is to assess the combined effects, on occlusal contact forces, of two previously studied affecting variables—occlusal detection products and saliva. Methods We used a full‐arch dentiform with three occlusal detection products (an articulating film, an articulation paper and T‐Scan) in combination with human (HS) and an artificial saliva. The maxillary arch assembly, weighing ~54 N (the maximum bite force), was lowered onto (occlusion) and lifted off (disclusion) of the mandibular arch through 10 cycles by a mechanical testing machine. The forces and moments acting on the mandibular arch were continuously recorded by a load cell that supported it. Results The maximum values of Flateral (the in‐occlusal plane component of the occlusal contact force) were analysed by occlusion/disclusion separately using one‐way ANOVA, with factor for group type to identify the significant effect of salivas on products, effect of products, effect of salivas with products, effect of human saliva. A difference in occlusion and/or in disclusion was considered different. Statistical differences (P < 0.0001) in Flateral were found in: dry product vs product + HS, dry product vs product + artificial saliva (with articulating film and T‐Scan) and HS vs product + HS (with articulation paper and T‐Scan). Conclusion All products were affected by the salivas, except articulation paper by artificial saliva.
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    Does the presence of an occlusal indicator product affect the contact forces between full dentitions?
    (Wiley, 2017) Mitchem, Jesse A.; Katona, Thomas R.; Moser, Elizabeth A. S.; Department of Orthodontics and Oral Facial Genetics, School of Dentistry
    Studies have explored occlusal marking interpretation, repeatability and accuracy. But, when an occlusion detection product is interposed between teeth, direct tooth–tooth occlusal contact relationships are replaced by tooth-material-tooth structures. Thus, the marks cannot reflect the original contacts. This has been shown for single tooth pair contacts. The purpose of this laboratory study was to similarly examine full dentitions. A dentiform was set into Class I centric occlusion with the mandible supported by a load cell. The maxillary arch was guided by precision slides. As the weighted (~52 N) upper assembly was lowered onto and raised off the mandibular arch, the loads on the mandible were measured. With and without (control) occlusal marking material, the steps were as follows: (cleaning – control 1 – material 1) … (cleaning – control 6 – material 6). The six materials were as follows: Accufilm I and II, Rudischhauser Thick and Thin, Hanel Articulating Silk and T-Scan. Then, the six sets of (cleaning – control – material) measurements were repeated with the mandibular assembly shifted, in turn, by 0·1 mm in the Anterior, Posterior, Right and Left directions. The five (Centric and four 0·1 mm shifted) occlusal relationships produced grossly different tooth–tooth (control) load profiles. And, in general, these controls were affected, in different ways, by the marking products. Among the five conventional products, the Rudischhausers fared the worst and the electronic T-Scan was an extreme outlier. Thus, in general, popular occlusal detection products alter the occlusal contact forces, and therefore, their markings cannot characterise the actual occlusion.
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    The effects of salivas on occlusal forces
    (Wiley, 2015-05) McCrea, Emily S.; Katona, Thomas R.; Eckert, George J.; Department of Orthodontics and Oral Facial Genetics, IU School of Dentistry
    Contacting surfaces of opposing teeth produce friction that, when altered, changes the contact force direction and/or magnitude. As friction can be influenced by several factors, including lubrication and the contacting materials, the aim of this study was to measure the occlusal load alterations experienced by teeth with the introduction of different salivas and dental restorative materials. Pairs of molar teeth were set into occlusion with a weighted maxillary tooth mounted onto a vertical sliding assembly and the mandibular tooth supported by a load cell. The load components on the mandibular tooth were measured with three opposing pairs of dental restorative materials (plastic denture, all-ceramic and stainless steel), four (human and three artificial) salivas and 16 occlusal configurations. All lateral force component measurements were significantly different (P < 0·0001) from the dry (control) surface regardless of the crown material or occlusal configuration, while the effects of the artificial salivas compared to each other and to human saliva depended on the crown material.
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    A Qualitative Engineering Analysis of Occlusion Effects on Mandibular Fracture Repair Mechanics
    (SAGE-Hindawi, 2011-08) Katona, Thomas R,
    Objectives. The purpose of this analytical study was to examine and critique the engineering foundations of commonly accepted biomechanical principles of mandible fracture repair. Materials and Methods. Basic principles of static equilibrium were applied to intact and plated mandibles, but instead of the traditional lever forces, the mandibles were subjected to more realistic occlusal forces. Results. These loading conditions produced stress distributions within the intact mandible that were very different and more complex than the customary lever-based gradient. The analyses also demonstrated the entirely different mechanical environments within intact and plated mandibles. Conclusions. Because the loading and geometry of the lever-idealized mandible is incomplete, the associated widely accepted bone stress distribution (tension on top and compression on the bottom) should not be assumed. Furthermore, the stress gradients within the bone of an intact mandible should not be extrapolated to the mechanical environment within the plated regions of a fractured mandible.
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    The roles of wedging and friction in the mechanics of dental occlusal contacts
    (2019-04) Katona, Thomas R.; Eckert, George J.
    Objective: The primary aim of this project is to elucidate the basic mechanical engineering principles that govern and explain unexpected and counter-intuitive occlusal contact force measurements. Methods: Forces were measured on matched pairs of first molar denture, ceramic and stainless steel crowns during occlusion and disclusion, with human saliva and dry (control). The weighted maxillary assembly, guided by a precision slide, was lowered onto, and raised from, the mandibular crown. The forces experienced by the mandibular tooth were continuously measured by the load cell that supported it. Statistical analyses included LOESS smoothing splines and generalized additive models. Principles of basic statics and classic friction were applied to explain and validate the results. Results: It was determined that within the span of a single chomp, the in-occlusal plane force component (Flateral) on the tooth is highly variable in direction and/or magnitude. The most salient observations were that Flateral was higher in disclusion than in occlusion, and the largest Flateral did not necessarily occur when the bite force was maximum. Furthermore, saliva significantly affected the results. Conclusions: The results demonstrated that contacting teeth experience complex transient mechanical environments that can be readily explained with elementary engineering principles involving wedging and friction at the occlusal contacts.