Instant Restoration Of Maxillary Brown ? Defects With Digital Prosthesis:a Clinical Study

[Background and objective]Maxilla defects could lead to facial deformity,dysfunction,and terrible influence on quality of life.The restore technologies mainly included free flap,free bone flap and prosthesis.Prosthesis was more suitable for the restoration of Brown ?-? defects.However,the restoration of the conventional prosthesis was always performed 2 weeks after operation.Some deficiencies were found about conventional prosthesis,for example difficulty in impression,facial skin contracture,poor accuracy,and delayed restoration.Because of these deficiencies,the prosthesis was applied to restore Brown II defects in surgery by means of digital technology.The free flap group was set as the control group.The facial form and function were evaluated and the quality of life between two groups were compared after reconstruction.The study was proposed to apply digital prosthesis to repaire Brow ? defects instantly and provide a feasible option to surgeons.[Materials and methods](1)Eight patients with maxillary primary tumor or malignant tumor involving maxilla were included in instant prosthesis group.Before surgery,surgical guides and prosthesis was designed and manufactured with virtual surgery and 3D printing.The partial maxillectomy was preformed with surgery guides and checked with computer assisted navigation.Prosthesis was worn to repair Brown ? defects instantly in operation.Two weeks after surgery,the CBCT images were compared to evaluate surgical accuracy between pre-operation and post-operation.(2)The other eight patients with Brown ? defects were treated by anterolateral thigh myocutaneous flap.They were set the flap group.3D photograph was taken to evaluate facial symmetry after surgery.The evaluation contents before and after insertion of prosthesis included intercommissural width,differences of bilateral lip height,maximum and average distance,nasolabial angles,skewed degree of mouth corner,variation area volume and superficial area.The speech intelligibility,deglutition,masticatory function,facial symmetry and quality of life were statistical evaluated between two groups at 1,3 and 6 months postoperatively.[Results](1)Prosthesis was worn smoothly in instant prosthesis group intraoperatively The well occlusion was acquired.The positive rate of cutting edge in operation was 12.5%(1/8).The wound had no infection.There was no recurrence in all patients during follow-up period of 6?18 months.(2)Maximum deviation between actual and virtual surgery was(3.75±0.78)mm,and average deviation was(0.35±0.08)mm.(3)Self-control of the instant prosthesis group:Speech intelligibility improved significantly after wearing prosthesis(P=0.004,0.015,0.001,P<0.05).Deglutition was improved up to 1-2 levels with effective rate 25%(2/8)and apparent rate 75%(6/8)The nasolabial angles,skewed degree of mouth corner,difference of bilateral lip height,maximum distance between healthy and affected sides and variation area volume decreased significantly(P=0.007,0.044,0.039,0.042,P<0.05).The intercommissural width increased significantly(P=0.001,P<0.05).The facial symmetry was improved significantly.The average distance between healthy and affected sides and superficial area were not significant(P=0.157,0.109,P>0.05).(4)The statistical results between two group:The instant prosthesis group was superior to the flap group based on the speech intelligibility(P=0.021,P<0.05).The prosthesis could restore a certain degree of masticatory function:The rate of occlusal force of the affected side was(20.45±2.55)%.The rate of occlusal force of the contralateral side was(79.55±2.55)%.The asymmetry index of occlusal force was(59.10±5.09)%.The recovery rate of occlusal force at the affected side ranged from 20.19%to 32.28%,and the average was 25.82%.No significant difference was found between deglutition and quality of life(P=0.599,0.612,P>0.05).[Conclusions](1)Prosthesis with the application of virtual surgery,surgical guides and 3D printing could precisely repair Brown ? defects in operation.(2)Instant restoration of prosthesis could significantly improve the speech intelligibility,swallowing function,facial symmetry,and restore a certain masticatory function.(3)Through functional evaluation,the digital prosthesis could instantly repairBrown II defects,which was superior to the anterolateral thigh musculocutaneous flap in speech intelligibility and masticatory function.