ABSTRACT
Objective To study the effects of different parameters (thickness,orthodontic displacement,elastic modulus) from Invisalign on canine displacement and periodontal ligament (PDL) stress during mandibular canine intrusion treatment.Methods Forty-eight different Invisalign models were used to simulate canine intrusion treatment by using the finite element method.Results The initial displacement of the canine and stress on canine PDL were proportional to the thickness,intrusion displacement,and elastic modulus of the Invisalign,and the intrusion displacement had the greatest influence on canine displacement.During canine intrusion treatment,the compressive stress on PDL was the most sensitive and changed easily with the change of parameters.Conclusions The canine displacement may increase with the thickness,intrusion displacement and elastic modulus of Invisalign increasing,however,the stress on PDL will also increase,showing the largest increasing magnitude in compressive stress on PDL meanwhile.Therefore,to accelerate tooth movement in Invisalign treatment,it is suggested to use the assisted devices or some other measures such as attachment,supplement of bracket-wires treatment,or implant anchorage.
ABSTRACT
<p><b>OBJECTIVE</b>To guide doctors in precisely positioning surgical operation, a new production method of minimally invasive implant guide template was presented.</p><p><b>METHODS</b>The mandible of patient was scanned by CT scanner, and three-dimensional jaw bone model was constructed based on CT images data The professional dental implant software Simplant was used to simulate the plant based on the three-dimensional CT model to determine the location and depth of implants. In the same time, the dental plaster models were scanned by stereo vision system to build the oral mucosa model. Next, curvature registration technology was used to fuse the oral mucosa model and the CT model, then the designed position of implant in the oral mucosa could be determined. The minimally invasive implant guide template was designed in 3-Matic software according to the design position of implant and the oral mucosa model. Finally, the template was produced by rapid prototyping.</p><p><b>RESULTS</b>The three-dimensional registration technology was useful to fuse the CT data and the dental plaster data, and the template was accurate that could provide the doctors a guidance in the actual planting without cut-off mucosa.</p><p><b>CONCLUSION</b>The guide template which fabricated by comprehensive utilization of three-dimensional registration, Simplant simulation and rapid prototyping positioning are accurate and can achieve the minimally invasive and accuracy implant surgery, this technique is worthy of clinical use.</p>