The purpose of this study is to test whether these two MMPs can be up-regulated during orthodontic treatment. Alveolar bone samples will be collected from partially impacted third molars after orthodontic uprighting for different period of time in volunteers.

Condition	Intervention	Phase
Orthodontic	Procedure: Orthodontic treatment	Phase I

Further Study Details: 

Primary Outcomes: Tissue staining with antibody
Expected Total Enrollment:  12

Long treatment time is a major factor causing high fee for orthodontic treatment. Patients would have dental caries or periodontitis resulted from improper oral hygiene care during this long treatment period. Therefore, how to speed up the tooth movement which determines the duration of orthodontic treatment, can help more people to obtain good occlusion and esthetics. Orthodontic force on tooth induces bone resorption on the compression side and bone deposition on the tension side, thus bone remodels and then tooth moves. Therefore, bone resorption is the rate-limiting step of a lengthy orthodontic treatment.

Bone resorption is a complex process. The mineral component is dissolved by acid from osteoclasts. On the other hand, the organic components are digested with proteolytic enzymes secreted from osteoblasts and osteoclasts. We focus on our study on specific proteases which can digest extracellar matrix, called matrix-metalloproteinases (MMPs). Osteoblast-derived MMPs play an important role during initiation of bone resorption. However, the mechanism of its regulation is not clear. The past studies applied stretching or tension on single layer of cultured cells to characterize cellular response to the mechanical stimulation. Now we simulate part of the bone resorption process by cultivating osteocyte-like cells in three-dimension collagen gel under periodical compression.

In preliminary study, we focus on transcriptional changes of MMPs upon compression in an osteosarcoma cell lines MG-63. Initial data form microarray indicated specific increase of two MMPs expression after one day of compression. This increased expression was specific because the levels of house-keeping genes (ex. Beta-actin or GAPDH) and bone-specific markers were unaltered. Therefore, we proposed that increased MMPs expression of osteoblasts under compression is the first step for bone remodeling switching from synthesis to degradation of osteoid. In order to test this hypothesis, the following specific aims will be achieved:

1. To test whether these two MMPs can be up-regulated during orthodontic treatment. Alveolar bone samples will be collected from partially impacted third molars after orthodontic uprighting for different period of time in volunteers. In situ hybridization and immunohistochemistry analysis for MMPs will reveal their roles in this physiological process.
2. To optimize the regulation by changing magnitude and frequency of pressure, and characterize the time table for these changes..

Ages Eligible for Study:  18 Years   -   35 Years,  Genders Eligible for Study:  Both

Accepts Healthy Volunteers

Criteria

Inclusion Criteria:

• two mandibular third molars containing at least one mesially anugular impaction with crown exposed to oral cavity

Exclusion Criteria:

• pregnancy

Please refer to this study by ClinicalTrials.gov identifier  NCT00154518

Chung-Chen Yao, DDS, PhD      886-2-23123456  Ext. 7689    janeyao@ha.mc.ntu.edu.tw

Taiwan
      Department of Dentistry, National Taiwan University Hospital, Taipei,  Taiwan; Recruiting

Study chairs or principal investigators

Chung-Chen Yao, DDS, PhD,  Principal Investigator,  National Taiwan University Hospital   

Study ID Numbers:  9261701411
Last Updated:  September 9, 2005
Record first received:  September 9, 2005
ClinicalTrials.gov Identifier:  NCT00154518
Health Authority: Taiwan: Department of Health
ClinicalTrials.gov processed this record on 2005-09-13