Initial Stress In The Periodontal Membrane Of Maxillary Anterior Teeth With Different Alveolar Bone Height By Retraction: A 3-dimensional Finite Element Analysis

Objectives: By the way of establishing the three-dimensional finite element models of maxillary anterior part with different alveolar bone height, this study aims to analyze the initial stress of PDL while retracting the six maxillary anterior teeth tippingly or bodily, in the hope that the clinicians can refer to this study while retracting maxillary anterior teeth in different periodontal conditions.Methods: Get the 2-D sectional images by scanning maxillary teeth with spiral CT,then input this images into ANSYS to establish the 3-D finite element digital models of maxillary anterior part with normal alveolar bone height, including teeth, periodontal tissue and archwire. After that, based on the first model, establish the models of maxillary teeth with horizontal balanced alveolar bone loss by deleting the elements. Then, load to these already established models to analyze the initial stress of PDL in these models when tipping and bodily movement respectively.Results: 1 3-D finite element models of maxillary anterior teeth with different alveolar bone height are established, which including teeth, periodontal tissue and archwire. 2 The initial stress distribution of PDL in the models and the extent of stress with the different alveolar bone height while tipping movement is obtained. 3 The initial stress distribution of PDL in the models, the extent of stress and M/F ratio with the different alveolar bone height while bodily movement are obtained.Conclusions: 1 The stress is concentrated in alveolar bone crest and apex area of the maxillary anterior teeth while they are in tipping movement. The stress is increasing with the alveolar bone loss, especially when the loss beyond the cervical one third of the root,which reminds while retracting maxillary anterior teeth tippingly, it is the light force to need. 2 The stress distribution in PDL is relatively equal while bodily movement. The stress is increasing gently with the alveolar bone loss. It reminds while retracting the maxillary anterior teeth with alveolar bone loss bodily, the force needs to be decreased and the M/F ratio needs to be increased proportionly.