| Background:Mini-implants in the application of orthodontic treatment is considered to be a technical innovation of the contemporary orthodontics.Its advantage,such as flexible to use,low cost,minimal invasion,makes the orthodontists do not rely on the traditional anchorage device that may need patients use by themselves to resist the unwanted tooth movement.As the "absolute anchorage",mini-implant anchorage can prevent the patients with mild maxillofacial deformities from orthognathic surgery.However,many orthodontists are troubled by the looseness and falling of the miniimplants during the orthodontic treatment.The failure rate of the implant anchorage after implantation is around 10%-30%,and an important reason for the failure is that the mini-implant is too close to the root of tooth due to the imprecise implantation site and orientation.The movement of the root during chewing causes the mini-implant to contact the root,thus loosing and falling off.In order to determine the implantation site and direction,the conventional method adopts X-ray plain film to observe the root position of the tooth.Orthodontists implant the mini-implant according to the experience of themselves with low accuracy.Inspired by the implant guide plate for dental prosthesis,this study used CBCT and intraoral scan data to design a new type of mini-implant guide plate,and used the guide plate to guide the mini-implant implantation,so as to improve the accuracy of implant location and direction,and thereby improve the success rate of mini-implant implantation.Objective:CBCT and intraoral scan data were used to design a new mini-implant guide plate,and the success rate of traditional implant method and guide plate guided implantation was compared by case-control method,so as to provide a reference for clinical application.Contents:1.A retrospective study on the success rate of mini-implant implantation2.Development of a new 3D printing guide plate for orthodontic mini-implant3.A control study on the success rate of mini-implant implantation guided by a new type of guide plate Methods:1.Medical records in the last eight years from 2010 to 2017 were collected,and patient factors(age,gender),micro-implant factors(length,diameter),implant location factors(upper and lower jaw,anterior and posterior)were determined as study variables.The above factors that may affect the success rate of micro-implant implantation were analyzed retrospectively.2.CBCT scan and intraoral scan were performed on patients with malocclusion that required implantation of micro-implant anchorage.CBCT data stored in DICOM format and STL data from intraoral scan were imported into the software of 3Shape Implant Studio for superposition,and 3D model of the maxilla and mandible was reconstructed.According to the requirements of vertical bone surface of the micro implant,no damage to the root,maxillary sinus and other tissues,and as far as possible parallel to the root,the mini-implant guide was designed on the reconstructed maxilla and mandible model and printed by Formlabs2 3D printer.During the operation,the position and orientation of the mini-implant were determined by the guide plate.After the operation,CBCT was used to evaluate the implant position and implant orientation.3.A total of 32 patients with malocclusion requiring the implantation of miniimplants between the bilateral maxillary second premolars and the first molars were selected,12 of whom were treated from January 2018 to June 2019 as the experimental group,and 20 of whom were treated from January 2016 to January 2018 as the control group.Patients in the experimental group were guided by a guide plate designed based on CBCT and intraoral scan data,and 24 mini-implants were implanted.In the control group,the same orthodontist implanted 40 mini-implants by localization method of the traditional X-ray films.The mini-implants of two groups were immediately applied tooth movement force after the implantation.Study observed the looseness or falling of the two groups of implanted mini-implants during clinical use for 6 months.Results:1.A total of 143 mini-implants loosed or falled off within six months,with a total failure rate of 17.61%.The success rate of mini-implant implantation was correlated with patient age,implanting location.2.In clinical application,the guide plate is well positioned,closely fits with the supporting teeth,and has good retention force.After the patient is instructed to bite,the guide plate is stable without displacement.The mini-implant was smoothly implanted along the zirconia guide ring.It is easy to remove the guide plate after operation.The accurate location and orientation of implantation were verified by CBCT.3.Check mini-implant clinical mobility after implantation,and observe its mobility within 6 months after implantation.The results show that all the 24 mini-implants in the experimental group did not loose or fall off,while in the historical control group 7 of 40mini-implants loosed or fall off.Mini-implants implantation success rate between the two groups was statistically difference(P < 0.05).Combined with clinical,it prompt the by using guide plate,mini-implant implantation success rate is higher than traditional methods.Conclusions:1.The failure of mini-implant implantation was correlated with the age and location of the implant.The success rate of mini-implant implantation in adult patients with higher cortical bone density was higher than that in adolescent patients.The stability of the mini-implant implanted in the maxilla is generally higher than that in the mandible,and the stability of the mini-implant implanted in the anterior is generally higher than that in the posterior.We can infer that the location and direction of the mini-implant are the key factors influencing the implantation of mini-implant.2.The development of new type of mini-implant guide plate is successful.Upon verification by CBCT,the mini-implant position and orientation is accurate.This method is simple to operate,and the price is low.However,the success rate of mini-implant implantation guided by this guide requires further analysis in subsequent case-control studies.3.The new mini-implant guide plate has high precision,can improve the success rate of mini-implant implantation,and is worthy of clinical application.However,due to the small sample size,the experiment still needs further verification. |
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