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Root Resorption Related to Hypofunctional Periodontium in Experimental Tooth Movement
S. Sringkarnboriboon,
Y. Matsumoto* and
K. Soma
Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Science, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan;
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Figure 1. Experimental schedule and orthodontic appliance fixed to the left mandible of the rat. (A) Diagram demonstrates the schedule of the entire experiment in both normal periodontium and hypofunctional periodontium groups. Hypofunctional periodontium was established by 3 wks in the hypofunctional periodontium group. (B) The hypofunctional left mandibular first molar was mesio-occlusally moved by an orthodontic appliance consisting of a 1.0-mm-diameter, 3.5-mm-long titanium-screw implant fixed to the left body of the mandible, with a 1.2-mm-diameter cobalt-chromium alloy wire extending along the incisal axis and a 2-mm-long 50-gram-force titanium-nickel alloy closed-coil spring. On the occlusal surfaces of the left maxillary third molar and right maxillary first to third molars (not shown), composite resin was applied for bite-raising in the hypofunctional periodontium group.
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Figure 2. Histological comparison of normal and hypofunctional periodontium after bite-raising for 3 wks at the disto-apical third region of the distal root. The reduction in periodontal width, atrophic changes, and derangement of the functional principal collagen fibers in the hypofunctional periodontium group (B) could be observed when compared with the normal periodontium group (A). PDL, periodontal ligament; B, alveolar bone; T, Tooth; Bar = 100 µm.
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Figure 3. Active root resorption lacunae of normal periodontium (A,B) and hypofunctional periodontium (C,D) groups stained with tartrate-resistant acid phosphatase (A,C) and hematoxylin and eosin (B,D). The newly formed resorption lacunae were identified by the presence of TRAP-positive multinucleated cells, the odontoclasts. Root resorption had occurred on the disto-apical third of the distal root facing the alveolar bone in the compression zone. In the hypofunctional periodontium group, the roots were resorbed extensively into dentin after 15 days of orthodontic movement. The black line indicates the resorption lacunar length. PDL, periodontal ligament; B, alveolar bone; T, Tooth; Bar = 250 µm.
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Figure 4. Quantitative analysis of active root resorption in normal and hypofunctional periodontium groups. The root resorption lacunar length (A), depth (B), and area (C) after 15 days of experimental tooth movement revealed that the root resorption in the hypofunctional periodontium group was significantly greater than that in the normal periodontium group (* = p value < 0.05). The horizontal lines of the box and whisker-plot diagram represent the 95th, 75th, 50th, 25th, and 5th percentiles, ordering from the top.
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Journal of Dental Research, Vol. 82, No. 6,
486-490 (2003)
DOI: 10.1177/154405910308200616
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