Effects of Decreased Occlusal Loading during Growth on the Mandibular Bone Characteristics

Hichijo, Natsuko; Tanaka, Eiji; Kawai, Nobuhiko; Ruijven, L.J. van; Langenbach, G.E.J.

doi:10.1371/journal.pone.0129290

Cited by 26 publications

(26 citation statements)

References 31 publications

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“…Especially, jaw muscle function has a considerable effect on craniofacial morphology. We reported previously in soft diet‐fed rats that a decrease in masticatory demand led to masseter muscle atrophy (Kawai et al, 2010) and inferior mandibular development (Hichijo et al, 2014; Hichijo, Tanaka, Kawai, van Ruijven, & Langenbach, 2015). The low muscle performance might be the reason of the effectiveness of chewing exercise in the dolicho facial subjects.…”

Section: Discussionmentioning

confidence: 95%

Effects of gum chewing exercise on maximum bite force according to facial morphology

Shirai

Kawai

Hichijo

et al. 2018

Clinical & Exp Dental Res

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Development of the masticatory system is influenced by functional needs. Furthermore, masticatory exercise can improve masticatory function. The aim of this study was to evaluate the potential effect of the gum chewing exercise on the maximum bite force (MBF) in adult subjects with different facial morphologies. MBF was measured by a portable occlusal force gauge and lateral cephalogram was used for evaluation of craniofacial morphology in 19 individuals (7 males and 12 females) with a mean age of 25.4 years (SD ± 4.3). The volunteers underwent gum chewing exercise for 5 min twice a day for 4 weeks. MBF was measured before (T1) and after the 4‐week exercise (T2). The facial morphology of the subjects was classified into the brachy (n = 7), mesio (n = 7), and dolicho (n = 5) facial types. In all three groups, exercise was associated with a significant increase in MBF, though the percent increase was highest in the dolicho facial type. We conclude that gum chewing exercise can improve masticatory performance, especially in individuals with dolicho facial morphology.

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Section: Discussionmentioning

confidence: 95%

Effects of gum chewing exercise on maximum bite force according to facial morphology

Shirai

Kawai

Hichijo

et al. 2018

Clinical & Exp Dental Res

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“…During the transition from the prenatal to postnatal stages, the mandible and the masticatory apparatus adapt to significant variations in the biomechanical forces that are associated with the development, emergence and eruption of the dentition (Herring, 1985;Mavropoulos et al 2005;Sato et al 2005). Loading conditions acting on the mandible are thought to play a marked and influential role in the modelling and remodelling of bone (Herring, 1985;van Eijden, 2000;Koolstra, 2002), with site-specific effects on the bone mineral density (van Eijden, 2000;Ruffoni et al 2007;Hernandez, 2008;Roschger et al 2008;Cioffi et al 2010;Hichijo et al 2015). As such, it may be expected that the effects of increased biomechanical loading on bone mineral density are particularly evident during the functional transition from the prenatal to the postnatal stages of growth, within the immature mandible.…”

Section: Introductionmentioning

confidence: 99%

“…the amount of mineralised bone associated with bone density, they did not specifically assess changes in the degree of mineralisation of the mineral component of bone density (Mavropoulos et al 2004(Mavropoulos et al , 2005Roschger et al 2008). Volumetric density changes serve as valuable indicators of the biomechanical potential of bone, while bone mineral density distributions provide an indication of its strength, stiffness and toughness (Ruffoni et al 2007;Hernandez, 2008;Roschger et al 2008;Cioffi et al 2010;Hichijo et al 2015). Furthermore, bone mineral density distributions assist in predicting the pattern of biomechanical force and strain across a developing bone, through the identification of areas of bone presenting with low levels of mineralisation and a higher degree of bone modelling and remodelling (Roschger et al 2008;Cioffi et al 2010;Hichijo et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Variations in bone density across the body of the immature human mandible

et al. 2017

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During growth the mandible accommodates increases in biomechanical loading resulting from changes in the function of structures of the oral cavity. Biomechanical loads are thought to play an intricate and vital role in the modelling and remodelling of bone, with site-specific effects on bone mineral density. It is anticipated that the effects of this loading on bone mineral density are intensified during the functional transition from prenatal to postnatal stages. The aim of this study was thus to evaluate changes in bone mineral density across the body of the immature human mandible during the early stages of dental development. The study sample included 45 human mandibles, subdivided into three age groups: prenatal (30 gestational weeks to birth; n = 15); early postnatal (birth to 12 months; n = 18); and late postnatal (1-5 years; n = 12). Mandibles were scanned using X-ray micro-computed tomography. Eight landmarks were selected along the buccal/labial and lingual surfaces of each dental crypt for evaluation of the bone mineral density. Bone mineral density values were calculated using a reference standard and analysed using multivariate statistics. The bone mineral density of the lingual surface was found to be significantly higher (P ≤ 0.000) than that of the buccal/labial surface. Furthermore, bone mineral density in the alveolar region of the buccal/labial surface of the deciduous central incisor (P ≤ 0.001), the deciduous first molar (P ≤ 0.013) and lingual alveolar area of the deciduous second molar (P ≤ 0.032) were significantly greater in the early postnatal period than in the prenatal period. While changes in bone mineral density across the lingual surface were consistent with the progression of development and the biomechanical demand of the tongue as previously demonstrated, changes observed across the buccal/labial surface of the mandible appeared to accompany the advancing dental development. Thus, changes in bone mineral density across the mandible appear to be reflective of the stage of dental development and the level of biomechanical loading.

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“…The lumbar vertebrae remain unchanged because running involves less direct loading. We speculate that the altered structure of the mandible can be attributed to the lower food intake observed during the endurance training protocol (Hichijo et al 2015), although there was a greater Tb.N in the mandible, which we cannot fully explain. Endurance exercise in growing male rats has skeletal site-specific effects, suggesting that the effect of bone loading during treadmill running is localized.…”

Section: Discussionmentioning

confidence: 90%

Skeletal site-specific effects of endurance running on structure and strength of tibia, lumbar vertebrae, and mandible in male Sprague–Dawley rats

Bott

Sacco

Turnbull

et al. 2016

Appl. Physiol. Nutr. Metab.

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Bone microarchitecture, bone mineral density (BMD), and bone strength are affected positively by impact activities such as running; however, there are discrepancies in the magnitude of these effects. These inconsistencies are mainly a result of varying training protocols, analysis techniques, and whether or not the skeletal sites measured are weight bearing. This study's purpose was to determine the effects of endurance running on sites that experience different weight bearing and load. Eight-week-old male Sprague-Dawley rats (n = 20) were randomly assigned to either a group with a progressive treadmill running protocol (25 m/min for 1 h, incline of 10%) or a nontrained control group for 8 weeks. The trabecular structure of the tibia, lumbar vertebra (L3), and mandible and the cortical structure at the tibia midpoint were measured using microcomputed tomography to quantify bone volume fraction (i.e., bone volume divided by total volume (BV/TV)), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), and cortical thickness. BMD at the proximal tibia, lumbar vertebrae (L1-L3), and mandible was measured using dual energy X-ray absorptiometry. The tibia midpoint strength was measured by 3-point bending using a materials testing system. Endurance running resulted in superior bone structure at the proximal tibia (12% greater BV/TV (p = 0.03), 14% greater Tb.N (p = 0.01), and 19% lower Tb.Sp (p = 0.05)) but not at other sites. Contrary to our hypothesis, mandible bone structure was altered after endurance training (8% lower BV/TV (p < 0.01) and 15% lower Tb.Th (p < 0.01)), which may be explained by a lower food intake, resulting in less mechanical loading from chewing. These results highlight the site-specific effects of loading on the skeleton.

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Effects of Decreased Occlusal Loading during Growth on the Mandibular Bone Characteristics

Cited by 26 publications

References 31 publications

Effects of gum chewing exercise on maximum bite force according to facial morphology

Effects of gum chewing exercise on maximum bite force according to facial morphology

Variations in bone density across the body of the immature human mandible

Skeletal site-specific effects of endurance running on structure and strength of tibia, lumbar vertebrae, and mandible in male Sprague–Dawley rats

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