BACKGROUND:Micro-implants of a small size may injure the maxillary sinus,adjacent tooth roots and mandibular nerves during implantation surgery,which requires precise positioning and accurate implant orientation.OBJECTIVE:To explore the clinical value of a cone-beam CT-based three-dimensional(3D)printing guide plate for guiding orthodontic micro-implant nail implantation.METHODS:Sixteen patients admitted to the Stomatology Hospital of Guizhou Medical University from December 2021 to December 2023 who required implantation of micro-implant anchorage were selected.The CT scan data of the patient's dental jaw from the infraorbital margin to the hyoid bone were collected and imported into Mimics 17.0 for threshold segmentation to obtain a 3D model of the crowns,roots,and bone cortex,and a digital model of the patient's intra-oral hard and soft tissues was scanned with the iTero Oral Scanner.The CT images were optimally overlapped with the intraoral scan model to design and fabricate a micro-implant guide plate.Sixteen implants were placed under the guidance of this plate.Postoperative cone-beam CT images were taken for 3D reconstruction and distance between the micro-implant and the layer closest to the tooth was measured to assess the safety of micro-implants.Cone-beam CT images were compared before and after surgery,and deviation between micro-implant crown and tip and angle deviation between micro-implant crown and tip were measured.Orthodontic follow-up was performed for 6 months to record micro-implant loosening and detachment.RESULTS AND CONCLUSION:No contact between the 16 anchorage nails and the tooth root or adjacent tissues was found in the postoperative images.Results of the comparison of preoperative and postoperative images indicated that the cap end deviation was(1.07±0.65)mm,the tip deviation was(1.51+0.47)mm,the angle deviation was(7.40+4.63)°,and the distance between the micro-implant and the layer closest to the tooth was(1.17±0.45)mm.There were 10 micro-implants of safety grade Ⅰ and 3 of safety grade Ⅱ.During the follow-up period,the 16 micro-implants did not loosen or fall off and had good stability.The orthodontic implant guide plate based on conical beam CT design can be used for implant implantation,and the preliminary study shows that the implant implantation guided by the guide plate is safe and stable.To conclude,the orthodontic micro-implant implantation guided by cone-beam CT based 3D printed guide plate has good accuracy and stability.

BACKGROUND:Micro-implants of a small size may injure the maxillary sinus,adjacent tooth roots and mandibular nerves during implantation surgery,which requires precise positioning and accurate implant orientation.OBJECTIVE:To explore the clinical value of a cone-beam CT-based three-dimensional(3D)printing guide plate for guiding orthodontic micro-implant nail implantation.METHODS:Sixteen patients admitted to the Stomatology Hospital of Guizhou Medical University from December 2021 to December 2023 who required implantation of micro-implant anchorage were selected.The CT scan data of the patient's dental jaw from the infraorbital margin to the hyoid bone were collected and imported into Mimics 17.0 for threshold segmentation to obtain a 3D model of the crowns,roots,and bone cortex,and a digital model of the patient's intra-oral hard and soft tissues was scanned with the iTero Oral Scanner.The CT images were optimally overlapped with the intraoral scan model to design and fabricate a micro-implant guide plate.Sixteen implants were placed under the guidance of this plate.Postoperative cone-beam CT images were taken for 3D reconstruction and distance between the micro-implant and the layer closest to the tooth was measured to assess the safety of micro-implants.Cone-beam CT images were compared before and after surgery,and deviation between micro-implant crown and tip and angle deviation between micro-implant crown and tip were measured.Orthodontic follow-up was performed for 6 months to record micro-implant loosening and detachment.RESULTS AND CONCLUSION:No contact between the 16 anchorage nails and the tooth root or adjacent tissues was found in the postoperative images.Results of the comparison of preoperative and postoperative images indicated that the cap end deviation was(1.07±0.65)mm,the tip deviation was(1.51+0.47)mm,the angle deviation was(7.40+4.63)°,and the distance between the micro-implant and the layer closest to the tooth was(1.17±0.45)mm.There were 10 micro-implants of safety grade Ⅰ and 3 of safety grade Ⅱ.During the follow-up period,the 16 micro-implants did not loosen or fall off and had good stability.The orthodontic implant guide plate based on conical beam CT design can be used for implant implantation,and the preliminary study shows that the implant implantation guided by the guide plate is safe and stable.To conclude,the orthodontic micro-implant implantation guided by cone-beam CT based 3D printed guide plate has good accuracy and stability.