Clinical Study Of Digital Altered Cast Impression Technique In Repairing Mandibular Distal Edentulous Dentition

Objective:Through the direct scanning of patients with mandibular distal edentulous dentition, the digital impression was obtained,after the 3D RPD scaffold was printed, the twice functional impression of distal edentulous dentition was taken,and the prosthesis was made after altered cast impression technique. The other prosthesis was made bytraditional method. To evaluate the effect of chewing, the adaptation of the prosthesis and the satisfaction rate of the patients. To explore the feasibility of digital altered cast impression technique in repairing the defect of mandibular distal edentulous dentition, and to provide reference and objective basis for the evaluation of clinical RPD repair effect.Methods:From July 2015 to July 2016, 15 patients with mandibular distal edentulous dentition were selected from the Department of Oral and Maxillofacial Surgery of Affiliated Stomatology Hospital of Kunming Medical University, finally 7 patients revisited which 2 cases were bilateral distal extension edentulous, 5 cases were unilateral distal extension edentulous. Detailed understanding of the patients'chief complaint, communicated with the patients, all of them were used 3 Shape scanner to obtain the digital impression,the data was saved in STL format and imported in 3D printing equipment,then 3D cobalt chromium alloy stent was printed.Make the individual tray on the basis of the production, and then the twice functional impression of distal edentulous dentition was taken. The prosthesis was made after altered cast impression technique, these are the experimental groups. The second denture was made according to the traditional repairing process as the control groups in the same time. Followed up for two months, through the clinical examination of the base of the degree of adhesion,visible spectrophotometer analysis of the same patient with two pairs of teeth after the restoration of chewing efficiency and patient denture satisfaction evaluation of its clinical repair effect.Result: Successful restored the patients with mandibular distal edentulous dentition and obtained the functional impression of distal edentulous dentition by applicant the 3 Shape digital altered cast technique. The patients were satisfied for the experimental groups prosthodontics in the first visit time.The base fabric was evenly stressed,the number of times of postural referral was significantly less than the control group ,the masticatory efficiency of the experimental group was significantly higher than the control group. The masticatory efficiency of the experimental group was significantly lower than that of the control group,The patients were satisfied for the experimental groups prosthodontics with the follow-up survey.Conclusion:1. The use of 3 Shape scanner directly through the mouth scan to obtain impression data, through the CAD data into the rapid protector, direct 3D print out the prosthesis bracket, to ease the preparation of the patient impression material, gypsum model perfusion cumbersome. The dental technician stent wax carving, embedding,casting, saving the patient's treatment time. Saving material and manpower resources,improve the accuracy of the production of the stent.2. On the basis of the stent on the record of the occlusal relationship, the twice functional impression of distal edentulous dentition was taken, the prosthesis was made after altered cast impression technique to complete the production of denture,Compared with pressure impression and anatomical impression, functional impression better reflect the distal edentulous soft tissue functional status,reduce the saddle sinking at the functional loading.3.The successful use of digital impression model replacement technique to repair the absence of mandibular distal edentulous, follow-up survey patients expressed satisfaction.Provide a reference and objective basisfor clinical RPD repair.4.Closed mouth impression can be used to prepare a functional impression for the patients with the mandibular distal edentulous dentition,then the prosthesis was made by this method.'5. Digital altered cast impression technique is a feasible way to improve the quality of mandibular distal edentulous dentition.