| [Objective]This research through the collection of maxillary edentulous jaw digital impression,analysis and comparison the accuracy of direct and indirect intraoral digital impression used in edentulous;analysis and comparison the regional deviations of the anatomic and pressure impressions,and obtain the subsurface parameters of the pressure impression,provide the basic data reference for the future digital pressure press;digital simulated the model processing of the post embankment area and frenulum soft tissue plastic of the lip.[Methods]The maxillary anatomic model was obtained by traditional method of taking 10 cases of maxillary edentulous jaws.The TRIOS scanner which producted by 3shape was used directly obtain the digital maxillary impression,marked direct impression group(DP);BPS type individual tray was used to get the anatomical impression,then the models using the TRIOS scanner and 3shape810 scanner respectively in the scan,mark oral scaning impression(OP)and the indirect impression group(IP).The optimal fitting deviation analysis was carried out in the Geomagic wrap software.A total of 20 cases of maxillary edentulous patients were involved in th research,a anatomical and pressure type individual tray were made on the basis of primary model,pressure tray include open-mouth type and closed-mouth type,then using anatomic individual tray and alginate to make maxillary anatomical impression,assuming no pressure on the relative reorganized impression mucosa,marked non-pressure impression group(control);using two-impression method,pressure type individual tray and with silicone,marked the opening impression-group(OP);using secondary-methods,temporary base and silicone to get the closed impression,marking a closed impression group(CP);the three group model were transferred to the digital impression by 3shape810 scanner.The opening impression group and the non pressure impression group,the closed impression group and the no pressure impression group were poured into the Geomagic software respectively.After the best fitting,the deviation analysis was carried out.Based on the functional area division of the model,the pressure deviation in each area was obtained.The deviation analysis is carried out by another fitting method,and the difference in the size of the deviation is comparedResults were calculated by spss22.0 software,ANOVA analysis methods were used to compare the the size of regional deviation,direct and indirect scanning precision of edentulous and comparison of the pressure changes in the regional area by the method of open-mouth and closed-mouth.the value of p<0.05 was statistically significantFinally,the artificial engraving of thepostdam and the movement of the lip frenulum are simulated through the migration function of the Geomagic software,so that the anatomical mould can achieve the digitalization of muscle function.[Results]There has a significant difference in the DP group,OP group and IP group(P=0,0.012,0.000<0.05),with 3shape desktop scanner anatomical model as control,error in scan was 0.312 ±0.085mm,the precision of the model deviation was 0.125±0.056mm that was over standard error which was proposed 50um.The pressure model has statistical significance(P=0.000<0.05)compared with the anatomic model.There were statistical differences between the open and closed impression methods.When the best fitting method is used,the relative dissection of the press has a negative deviation.The pressure deviation of OP and CP has a significance different.The overall deviation of the OP group was 0.397±0.184mm,the alveolar ridge area was the least that is 0.158±0.052mm,the palatal wrinkle area,the maxillary hard area and the back dike area were 0.234±0.122,0.220±0.131,0.267±0.159mm,respectively.While the overall deviation of the CP group was 0.997±0.287mm,the alveolar ridge area was the least that is 0.209 ±0.067mm,the palatal wrinkle area,the maxillary hard area and the back dike area were 0.439±0.196,0.448±0,174,0.580±0.261mm,respectively.There were statistical differences in all regions.When the area fitting method was applied,the overall deviation of the open impression group was 0.678±0.319mm,the alveolar ridge area was 0.129±0.065mm,the palatal wrinkle area,the maxillary hard area and the back dike area were 0.307±0.140,0.340±0.122,0.366±0.154mm,respectively.The deviation was obviously increase and there is a same trend of two fitting methodsAfter treatment,the area of the post dike area was descended from the back to the front,and the maximum data of the final margin was 1mm,and gradually moved along with the mucous membrane.The base of the complete denture formate the V shape on the labial frenulum after the cutting.[Conclusions]1.Taking the data scanning mode of 3shape810 as a control,the accuracy of direct impression acquisition of edentulous jaws in TRIOS oral scanner is about 300um.The precision of the indirect scanning model is about 100um.It is indicated that intraoral environmental factors are important reasons for scanning edentulous jaws than scanning fixed dentures.2.The pressure impression has different subsidence deviations in each functional area of the edentulous jaw,of which the offset of the alveolar ridge is the smallest and the largest in the postdam area;The deviation trend of the closed pressure impression lies the same as that of the open type,and the deviation values are larger;The registration of the region fitting method can obtain more accurate deviation.3.The artificial engraving of the postdam area is realized by the mesh thickening method of the back embankment area on the base.According to this method,the numerical simulation of the pressure model can be simulated on the basis of the parameters in the experiment two.Through the overlap of the limit range of the frenulum,the inner surface of the base can be cut to achieve a simple digital muscle function simulation. |
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