Quantitative Study On The Reliability Of Occlusal Adjustment Methods For Single Molars In Different Sequences By Articulating Paper

Objective:To quantitatively evaluate the effectiveness,accuracy and reliability of occlusal adjustment methods in different sequences by articulating paper for single molar implant prosthesis from the perspectives of occlusal contact characteristics,organizational health,functional recovery and clinical applicability,and to investigate the optimal sequential grinding mode.To provide theoretical basis and data reference for clinical use of articulating paper to guide the occlusal adjustment and long-term maintenance of implantable dentureMethods:A total of 32 first molars(19 to 50 years old,13 males and 19 females)were selected from 32 patients with dentition defect who received single molar implant restoration in the Department of Prosthodontics,Affiliated Hospital of Youjiang Medical University for Nationalities from December 2019 to September2021.According to the occlusal adjustment method in different sequences designed,they were divided into 3 groups according to the random number table means,group A had 12 cases,group B had 10 cases,group C had 10 cases,corresponding to the groups of selective grinding by sequence articulating paper with(100+40),(100+50+30),(100+40+20)μm.In all patients,flapping non-embedded delayed implantation was used to complete the first-stage implantation.After making zirconia implant all-porcelain crown with open window transfer technology,corresponding occlusal adjustment was performed according to the group to complete the second-stage superstructure restoration.3 and 6 months after the repair,the corresponding occlusion examination was carried out,and the grinding was adjusted again if necessary.Tee Tester digital occlusal analysis technology and Cone-beam CT combined with Mimics software measurement technology were used to record the percentage of bite force,occlusal delay time,buccal,lingual and palatal bone tissue width and height around the implant for the implant prosthesis and adjacent natural teeth and the contralateral teeth of the same name(control teeth 1 and 2)before,on the day and 3 and 6 months after the restoration.At the same time,absorbance method was used to measure the mastication efficiency of the repaired side,and the number of cases needing to adjust teeth again and the time required to complete elaborate grinding were recorded in each group during the follow-up period,and the differences were analyzed and compared.Results:(1)Analysis of basic data of subjects:there were no statistically significant differences in age,gender,implant system,dental position,bite force percentage of control teeth 1 and 2 and masticatory efficiency of intraoperative area before repair at baseline among all groups(P>0.05);(2)Follow-up situation:a total of32 patients were followed up 3 months after repair.And a total of 31 patients were followed up at 6 months.(3)Analysis on the percentage of bite force of molar implant prosthesis in each group:compared with group B and C,the bite force in group A was smaller on the day and 3 and 6 months after restoration,and the difference was statistically significant(P<0.05).The longitudinal comparison within the groups showed a significant increase over time(P<0.01),and group C had the largest increase(P<0.001).(4)Intra-group comparison of the percentage of bite force between prosthesis and adjacent and contralateral teeth with the same name(control teeth 1 and 2):comparison between groups,repair the same day,after 3,6 months,each prosthesis although have increased,but were significantly lower than control teeth 1,2(P<0.01),implant light occlusal contact design in three groups were basically stable,minimum group A accounted for about 34.28%of the control teeth 2on that day,while maximum group C accounted for about 71.82%of the control teeth1 at 6 months after repair.(5)Analysis of occlusal delay time between dental prosthesis and control teeth 1 and 2:compared between groups,there were statistical differences in time between dental implants and control teeth 1 on the day of restoration(P<0.05),among which group A achieved the longest delay time,while group C achieved the shortest delay time;The delay time of prosthesis and control teeth 2 in group A was longer than that in group B and C,and the difference was statistically significant(P<0.01).At 3 and 6 months after restoration,both delay time in group A were shortened,but they were still larger than those in group C(P<0.05).Within the groups,before and after longitudinal comparison,the occlusal delay time of implant prostheses with adjacent teeth and contralateral teeth showed a decreasing trend,but there was still occlusal delay.(6)Comparison of changes in peri-implant bone tissue among all groups:compared with group A,buccal,lingual and palatal bone width and height were absorbed more in group B and C during the follow-up period(P<0.05);The buccal bone width in group A continued to decrease(P<0.05),while the lingual bone width changed from absorption to growth(P<0.01),and the other bone tissue indexes showed an increasing trend(P>0.05).Buccal,lingual and palatal bone width and height of group B and C increased before and after comparison,but there was no statistical difference(P>0.05).(7)Comparison of chewing efficiency(ABS value)on the repair side:there was no significant difference between groups at each time point(P>0.05).Within the group before and after the longitudinal comparison,each group showed a significant increase trend over time(P<0.001),pairwise comparison,the differences were statistically significant(P<0.01),among group C showed the largest increase from the day to 6 months of repair.(8)Comparison of the number of patients needing re-adjustment during the follow-up period:during the follow-up period,4 patients in group A were required to adjust again 3 months after restoration,and 3 patients were at 6 months after restoration,totaling 7 cases.There were 10 cases in group B and 15 cases in group C.There were statistically significant differences among all groups(χ~2=7.853,P<0.05).The number of cases requiring second adjustment after occlusal examination of implant prostheses in group A was relatively small(P<0.05),and group C was the most.(9)Comparison of the time required by the prosthesis to complete elaborate adjustment:the difference in the time required by each group was statistically significant(F=5.154,P<0.05).The group A was relatively short,and there were statistical differences compared with group B and C(P<0.05).(10)Correlation analysis of occlusal delay time and bite force percentage:the results showed that both had moderate positive correlation at each restoration time point in each group(P<0.01,0.3<r_s<0.5 is a moderate correlation):the larger the value of occlusal delay time was,the larger the difference of bite force percentage was.Conclusion:(1)The occlusal adjustment method in different sequences by articulating paper is effective,accurate and reliable for guiding the implant prosthesis occlusal adjustment of single molars.(2)In this study,the three groups of the method of selective grinding with sequential articulating paper can achieve the design of implant light bite and delay bite,and restore higher chewing efficiency.In the(100+40)μm sequence group,the dynamic changes of occlusal contact characteristics of the implant prosthesis were smaller,the occlusal stability was higher,the sensitivity of tooth adjustment was lower,and the chair-side operation efficiency was higher,showing stronger clinical applicability and practicability.Compared with(100+50+30)and(100+40+20)sequential grinding,it was more beneficial to maximize the health care of implant supporting tissue.(3)The occlusal characteristics of the patients in the three groups changed to some extent during the follow-up period.The smaller the occlusal contact space achieved by the sequential grinding method,the greater the change might be,requiring close follow-up visiting in clinical practice.