Elsevier

Archives of Oral Biology

Volume 58, Issue 8, August 2013, Pages 907-911
Archives of Oral Biology

Soft diet causes greater alveolar osteopenia in the mandible than in the maxilla

https://doi.org/10.1016/j.archoralbio.2013.02.003Get rights and content

Abstract

Objective

To investigate changes in the bony microstructure of the upper and lower alveolar bone during masticatory loading induced by soft diet feeding in growing rats.

Design

Three-week-old male Wistar rats were randomly divided into two groups. Rats were fed with either pellets [control group (n = 6)] or a soft diet [experimental group (n = 6)] for nine weeks. 3D-microstructure of the alveolar bone of the first molar region (M1) was examined by micro-CT analysis.

Results

Micro-CT images showed increased marrow spaces of the inter-radicular alveolar bone around the rat mandibular M1 in the experimental group compared with that in the control group. The bone volume/tissue volume ratio, trabecular thickness, trabecular number, mean intercept length, trabecular width and trabecular star volume for the mandibular M1 inter-radicular alveolar bone were lower in the experimental group than in the control group. Marrow space star volume was increased in the experimental group compared with the control group.

Conclusions

These results suggest that alveolar osteopenia is more extensive in the mandible than the maxilla in rats that experience low masticatory loading during growth.

Introduction

In rat models of occlusal hypofunction, bone formation is significantly suppressed in the bucco-lingual direction, and the stiffness of the alveolar bone is reduced.1, 2 The results of various studies have indicated that a soft diet during the developmental period causes a delay in the growth of the muscles of mastication and in jaw bone development5, 6 as well as changes in the growth of the viscerocranium.7

There are some disparities in the mechanisms of bone metabolism between the upper and lower jaw bones, particularly in terms of the pattern of bone resorption after the loss of teeth. Alveolar osteopenia in the edentulous mandible results in a knife-edge shape of the residual ridge, which contrasts to the smoother surface of the edentulous maxilla.8 Differences in bone remodelling were observed between the maxilla and mandible in tooth extraction model in dogs.9 Densitometry evaluation showed higher alveolar bone mineral density in the mandible as compared with the maxilla that was due to the thick cortical bone.10 A finite element human model demonstrated that occlusal load induced greater displacement of the mandibular teeth than the maxillary teeth at the time of occlusal contact.11 While the differential responses between the two jaw bones in response to diet have been examined, the changes to the bony microstructure between the maxilla and mandible in response to a soft diet are not thoroughly understood. The purpose of this study was to compare the alveolar bone microstructure in the upper and lower jaws in response to a soft diet during growth using micro-CT analysis.

Section snippets

Experimental model

Three-week-old male Wistar rats were randomly divided into a control group (n = 6) and an experimental group (n = 6). Rats in the control group were fed a standard pellet diet, while the rats in the experimental group were fed a diet in gel form (DietGel 76A, ClearH2O, Portland, Maine, USA) for 9 weeks. Body weight was monitored daily. After the experimental period, all animals were anesthetized with an interperitoneal injection and killed by cervical dislocation. The maxilla and mandible of each

Body weight

The body weights of the rats were monitored throughout the experimental period, and no significant differences were found between the soft diet and control groups.

Micro-CT images of alveolar bone structure

The marrow spaces of the inter-radicular alveolar bone were increased in the experimental group as compared with that in the control animals. This tendency was more prominent in the mandible (Fig. 3) than in the maxilla (Fig. 2).

Quantitative evaluation of alveolar bone structure

In response to a soft diet, the values determined for the Vm were increased both in the maxillary and

Discussion

Mechanical stress acting on the bone plays a crucial role in the maintenance of bone homeostasis, and a prolonged lack of mechanical stimulation leads to disuse osteoporosis.12 The unloading of occlusal forces to the alveolar bone results in atrophic changes in alveolar bone and periodontal tissue.13, 14, 15

This study revealed a greater impact of soft diet feeding on the mandibular alveolar bone than the maxillary alveolar bone in the M1 region. Micro-CT analysis showed a tendency towards lower

Funding

This study was financially supported in part by Grants-in-Aid for Scientific Research (23593020 and 22792042) from the Japanese Ministry of Education, Culture, Sports, Science and Technology.

Conflict of interest

None declared.

Ethical approval

The experimental procedures described here were approved by the Institutional Animal Care and Use Committee (#0110199A) and performed in accordance with the Animal Care Standards of Tokyo Medical and Dental University.

Acknowledgment

We wish to thank Nobuhito Nango (Ratoc System Engineering, Tokyo, Japan) for technical support and providing valuable advice for our micro-CT analyses.

References (23)

  • C. Engström et al.

    The relationship between masticatory function and craniofacial morphology: II. A histological study in the growing rat fed a soft diet

    European Journal of Orthodontics

    (1986)
  • Cited by (32)

    • Oral biosciences: The annual review 2022

      2023, Journal of Oral Biosciences
    • Compensatory dentoalveolar supraeruption and occlusal plane cant after botulinum-induced hypotrophy of masticatory closing muscles in juvenile rats

      2019, Archives of Oral Biology
      Citation Excerpt :

      To investigate changes in alveolar bone density, the micro-CT images were analyzed with software (CTAn, Bruker microCT, Konitch, Belgium). The region of interest was set at the furcation area of the mandibular first molar, which is known to be a region of concentrated occlusal force and is frequently used for alveolar bone histomorphometry (Enokida, Kaneko, Yanagishita, & Soma, 2005; Shimizu et al., 2013). Calibration of bone mineral density was conducted according to the system manufacturer’s protocol by scanning a water phantom and two hydroxyapatite phantoms of known density (0.25 and 0.75 g/cm3).

    • Recovery of atrophic parotid glands in rats fed a liquid diet by switching to a pellet diet

      2018, Archives of Oral Biology
      Citation Excerpt :

      Many experimental studies have shown that continuous intake of soft food, which is currently a popular dietary trend, negatively influences oral maxillofacial regions such as the jaw bones (Bozzini, Picasso, Champin, Bozzini, & Alippi, 2015; Hichijo et al., 2014; Shimizu et al., 2013), masticatory muscles (Fujishita et al., 2015; Kawai et al., 2010; Kitagawa et al., 2004) and temporomandibular joints (Kato, Takahashi, & Domon, 2015; Kiliaridis, Thilander, Kjellberg, Topouzelis, & Zafiriadis, 1999; Uekita, Takahashi, Domon, & Yamaguchi, 2015).

    View all citing articles on Scopus
    View full text