Evaluation Of The Feasible Of Intraoral Impressions For Jaws Defects & Oral Digital Prosthodontic Case Report

Part One.Feasibility analysis of intraoral scanning for making impressions of patients with maxillary defectsPurpose.The purpose of this study is to investigate the feasibility of digital intraoral scanning for making intraoral impressions of patients with maxillary defects and to provide a theoretical basis and data support for the production of digital obturators.Materials and Methods.Twenty models of 10 participants with maxillary defects were selected as the subjects.For each participant,three custom-made zirconia porcelain blocks（6mm*6mm*3mm）were attached to the healthy palatal mucosa using the medical tissue glue（Medical Tissue Glue,B.Braun Corp,China）.The porcelain block near the residual anterior teeth was marked as A porcelain block,the porcelain block near the posterior teeth was marked as C porcelain block,and the porcelain block near the defect area or flap area was marked as B porcelain block.Digital models were produced using the oral scanning system（Trios color,3Shape Corp,Denmark）and traditional plaster models were produced using silicone rubber impression material,respectively.The standard tessellation language（STL）data of the traditional impression（CI）plaster models were obtained using a model scanner（E2 Lab Scanner,3Shape Corp,Denmark）and imported into reverse engineering software（Geomagic Wrap,Raindrop Geomagic Corp,America）together with the STL data of intraoral scan（IOS）models for trueness assessment using the STL data from the CI as reference data,two separate measurements were performed for each set of models:a linear distance measurement between the porcelain block and the tooth,and a best-fit algorithm measurement for the teeth area.Data analysis was performed using statistical software（IBM SPSS Statistics,v26;IBM Corp,America）.A total of 20 models from 10 participants who met the requirements were analyzed for the study.The data included 30 groups of distance measurement data（30 sets of IOS data and 30 sets of CI data）and 10 groups of dental best-fit data.Results.In terms of distance measurements,the results of distance analysis of all 30groups suggested a significant difference between the trueness of IOS and CI（P=0.034）,and the results of distance analysis of porcelain block groups A and C showed that there was no significant difference between the trueness of IOS and CI impressions（P_A=0.628,P_C=0.517）,and the results of distance analysis of porcelain block group B suggested a significant difference between the trueness of IOS and CI.The results of the distance analysis of the B porcelain block group suggested that there was a significant difference in the trueness between IOS and CI（P_B=0.0.017）and the position of the porcelain block had a significant effect on the trueness of the impression.By using one-way ANOVA,differences in the trueness measurement were analyzed,the results suggested that there was a deviation of porcelain block location on impression trueness（P=0.049）,and the LSD results suggested that there was a significant difference in the trueness between group B and group C(P_BC=0.018)and not yet between group A and both group B and C(P_AB=0.109,P_AC=0.399).The Kolmogorov–Smirnoff test of the best-fit alignment revealed that no significant difference was found between CI and IOS groups in terms of the remaining dentition trueness（P=0.184）.Conclusion.IOS has satisfactory results in the trueness of the maxillary defect models,but there is still a necessity to take functional impressions to meet the clinical treatment needs.Part Two.Oral Prosthodontic Case ReportObjective.The aim is to collect cases of restoration of dental defects,dentition defects,and jaw defects with dentition defects,and to synthesize the restoration methods and effects combined with the literature.Methods.Five cases were selected for data collection and case analysis from patients who visited the Department of Prosthodontics between November 2018 and December 2020.According to the patients’ diagnosis and characteristics,restorative treatments such as veneers,single crowns,implants,and obturators were completed with the help of intraoral optical scanning,digital smile design,and gingival contouring,respectively.these cases were analyzed later in relation to the relevant literature,clinical experience,and relevant studies.Results.Five cases were restored for both types of dental defects and jaw defects with dentition defects.Digital Smile Design（DSD）and Computer-Aided Design（CAD）/Computer-Aided Manufacturing（CAM）techniques were applied in the veneer restoration of dental defects.The crown and veneers were manufactured using glass-ceramic materials.In the implant restoration of crown-root fracture of the anterior tooth,immediate implantation was adopted,and the gingival soft tissue in the implant area is gradually molded by temporary restoration.Also,the zirconia abutment on titanium substrate was selected to enhance the personalized aesthetic effect.In the case of mandibular bone defect with dentition defect,the implant-supported fixed partial denture（IFPD）was selected,and Bio-HPP material was used as the framework to reduce the weight of the denture,and the position information of the implant was obtained digitally,and the design and fabrication of the restoration were carried out digitally as well.The effect was satisfactory in terms of both accuracy and aesthetics.In the restoration of the maxillary defect with dentition defect,the initial impression was made by digital scanning.Although an intraoral functional impression was still required,it has significantly simplified the medical process and reduced the patient’s discomfort.Patients reported that the appearance and performance of the prosthesis were satisfactory.Conclusion.The application of digital technology creates more possibilities for restorative dentistry.It makes a series of advantages such as enhancing the aesthetic effect,shortening the restorative course,and facilitating patient-doctor communication.