The Initial Application And Exploration Of Digital Technology In Occlusal Evaluation And Analysis

Purpose:To evaluate the masticatory system in a normal young population using a relatively integrated and comprehensive digital method to clarify 1.the effect of TENS on occlusal contact,masticatory muscle potential values and mandibular movement trajectories in the normal he young population;and 2.the relationship between NMP（neuromuscular position）and ICP（intercuspal position）.Materials and methods:Twenty subjects（5 males and 15 females,mean 24.27±2.59years）were selected at Dalian Stomatological Hospital.Digital impressions of the subjects were taken by a trained operator and imported into T-Scan v10.1 software（Tekscan,Denmark）.The steps of this study were divided into four phases:pre-TENS acquisition,TENS intervention,post-TENS acquisition,and NMP recording.The pre-TENS phase was performed using the T-Scan Novus Occlusion Analysis System（Te Kscan,USA）,silicone materials（Blue Silicone,GC,Japan）,and DP2（Dental Prescale II Occlusion GC,Japan）to collect information on occlusal contacts in the subjects’ICO（intercuspal occlusion）and Clench（maximum voluntary clench）states.Each state was recorded 3 times for T-Scan and 1 time for silicone and DP2.The EMG（surface electromyography,Myotronics,USA）equipment was then used to collect the masticatory muscle potential values in the Rest,ICO,and Clench states,and each state was recorded five times.Four pairs of muscles,TA（temporalis）,MM（masseter）,SCM（sternocleidomastoid）,and DA（anterior of digastric）were acquired in the Rest state,and TA and MM were acquired in the ICO and Clench states.Potential values were collected from 2 pairs of muscles.Opening and closing velocity,resting gap and marginal movements were recorded 5 times for each state using a CMS（computerized mandibular scanner,Myotronics,USA）.During the TENS intervention phase,45minutes of J5（Dental TENS Unit,Myotronics,USA）were spent on recording the opening and closing speed,freeway space,and marginal movements.The post-TENS acquisition phase was the same as the pre-TENS phase.Finally,the NMP was recorded using occlusal recording silicone materials（topas PERFECT A85,Müller-Omicron,Germany）.The experimental data were recorded and the normality of each group was analyzed using the SPSS 26.0 statistical software（IBM,USA）Shapiro-Wilk test.If the data were normally distributed,paired t-test was used to compare the percentage of occlusal force,OCA（oclusal contact area）,OCN（oclusal contact number）,pressure,occlusal force,EMG mean value,As（asymmetry index）,opening and closing speed,freeway space,and marginal range of motion,and the differences were considered statistically significant at P<0.05;Ac（activity index）and To（torque index）were compared by independent t-test,and the differences were considered statistically significant at P<0.05.Results:The differences in the EMG mean values of TA,MM,LSCM,and RDA before and after TENS were statistically significant（P<0.05）.As MM,As SCM,and As DA decreased after TENS,and the difference in As DA before and after TENS was statistically significant（P<0.05）.The majority of subjects used MM to maintain the mandibular posture before TENS（12 vs.7）and mostly used TA to maintain the mandibular posture after TENS（13 vs.6）.Only 5%of subjects had no muscle prevalance during functional activity（Actot=0）,both before and after TENS,and Ac _TAwas significantly higher than Ac _MM（approximately 17%vs.13%before TENS and 15%vs.12%after TENS）.The left side of To decreased after TENS,and the difference in To before and after TENS was not statistically significant.In the ICO condition,No statistically significant difference between the percentage of maximum occlusal force and the percentage of maximum cusp crossover between the left and right side arches measured by T-Scan before and after TENS.The percentage of left and right side after TENS was closer to 50%.The OCA and OCN measured by silicone increased after TENS,and the differences between the right side OCA and full arch OCA and each data after TENS were statistically significant（P<0.05）.The OCA and pressure of the full arch measured by DP2 increased after TENS,and the OCA,pressure,and occlusal force of the left and right sides before and after TENS were closer to 50%.The difference between the EMG mean value of TA and MM was not statistically significant.As_totdecreased after TENS and the difference with pre-TENS was not statistically significant.TA was more active in more than 80%of subjects and Ac _TA was about 40%before TENS and about 49%after TENS.The left side To decreased after TENS and the difference between To before and after TENS was not statistically significant.In the Clench condition,the difference between the percentage of maximum occlusal force and the percentage of maximum cusp crossover measured by T-Scan on the left and right side before TENS and after TENS was not statistically significant.The OCA and OCN measured by silicone increased after TENS,and the difference between the values before and after TENS was not statistically significant.The total OCA measured by DP2 increased after TENS.Both left and right lateral OCA and occlusal force were closer to 50%.The differences between the EMG mean values of RTA,LMM,and RMM before and after TENS were statistically significant（P<0.05）.The EMG mean values of both TA and MM increased after TENS,and the increase in MM was greater than that of TA.The As_tot decreased after TENS,and the difference with was not statistically significant before and after TENS.MM was relatively active both before and after TENS,and Ac _MM was higher than Ac _TA.The To of the left side and right side decreased after TENS,and the difference between To before and after TENS was not statistically significant.The mean velocity of opening and closing increased after TENS;the freeway space increased by 0.12 mm;the degree of opening and maximum anterior extension increased,and the difference between maximum left and right laterality decreased.The NMP was located anterior to ICP 0.42 mm and 0.32 mm below.Conclusion:Within the limitations of this study the following conclusions may be drawn:1.There were significant differences of EMG average values of TA and MM after TENS in Rest condition,and no statistical differences in occlusal contact and mandibular movement data after TENS.2.The NMP was located 0.42 mm anterior and0.32 mm inferior to the ICP.3.The integrated use of digital means allows for more comprehensive collection of occlusal contact information,masticatory muscle potential values,and mandibular movement.The integration of these information can better guide clinical diagnosis and treatment.