Correlation Between Craniofacial Structural Features And Dentition Wear Distribution

Purpose:(1)To measure the amount of tooth wear in the general population,and to determine the basic characteristics of tooth wear.(2)To measure the amount of tooth wear and craniofacial morphology of the general population,and to value the influence of craniofacial structural features on the distribution of tooth wear.Method:(1)Caculation of tooth wear among the general population: A total of 103 subjects were enrolled in the present study.These 3D models were placed in the coordinate axis with a ruler using 3-matic Medical 13.0..Intercepted pictures were then imported into Adobe Photoshop CS6.Calculating the area of the irregular figure,the wear area of each tooth was obtained.Based on the result,the total wear area of the entire dentition,the maxillary incisors,the maxillary molars,the average wear area of the front teeth,the posterior teeth,and the ratio of the front to rear teeth are calculated.The T test was used to compare the maxillary incisors with mandibular incisors,find the differences between the maxillary posterior teeth and mandibular posterior teeth,together with different sexes and ages.The analysis of variance was used to determine whether there was a difference in tooth wear between three Angle’s classifications.(2)Craniofacial structural parameter measurement: Use Dolphin software to trace points on the lateral cephalograms to perform cephalometry,and determine six angles from these reference points and reference planes,respectively:(1)ANB(2)MP-FH(FMA)(3)FMIA(4)NP-FH(5)U1-L1(6)FH-Mx Occ Plane;.Correlation analysis was used to determine the relationship between cephalometric parameters and tooth wear.Result:(1)The total wear area of the whole dentition increases with age,and the difference is statistically significant(P = 0.01).For different genders,the total wear area was different,but it was not statistically significant(P = 0.46).Maxillary incisors had significantly higher wear than mandibular incisors(P = 0.013).,however,there were no significant differences in the wear area of the maxillary and mandibular molars(P = 0.46)and of the left and right sides(P = 0.31).A significant correlation can be seen between the total wear area of mandibular and maxillary incisors(r = 0.98,P <2e-16),of mandibular and maxillary molars(r = 0.92,P <2e-16),of the left and right sides(r = 0.94,P <2e-16).According to different Anchor classifications,it can be found that the average wear area of the anterior teeth is statistically different(P = 0.032),while the posterior teeth are not(P = 0.92).For the wear area of different tooth positions,it can be seen that the wear area of the canine has the largest proportion,followed by molars,incisors and premolars.(2)ANB angle showed a significant liner correlation in both the anterior tooth wear area(P = 0.002),the posterior tooth wear area(P = 0.008)and the total wear area(P = 0.014),while the ratio of anterior to posterior tooth wear area did not show any correlation(P = 0.974).MP-FH(FMA)showed a significant correlation with the wear area of the anterior teeth(P = 0.048),and a significant negative correlation can be found with the ratio of anterior to posterior tooth wear area(P = 0.017),while not with the wear areas of the posterior teeth(P = 0.686)and the overall(P = 0.232).FMIA showed a significant correlation with the average wear area of the posterior teeth(P = 0.014),but not with the average wear area of the anterior teeth(P =0.324),the ratio of anterior to posterior tooth wear area(P = 0.294)and the total wear area(P = 0.06).NP-FH showed no correlation with the average wear area of the front teeth(P = 0.834)the posterior teeth(P = 0.372),the ratio of anterior to posterior tooth wear area(P = 0.97)and the total wear area(P = 0.562).U1-L1 showed no correlation with the average wear area of the front teeth(P = 0.174)and the posterior teeth(P = 0.089),the ratio of anterior to posterior tooth wear area(P = 0.216)and the total wear area(P = 0.076).There was no significant correlation between the FH-Mx Occ Plane and the wear area of the anterior(P = 0.1309),posterior(P = 0.7623),and overall(P = 0.3481),however,there was significant negative correlation with the ratio of anterior to posterior tooth wear area(P = 0.0148).Conclusion:(1)Abrasion is an aging physiological phenomenon.The area of tooth wear increases with age,which is a significant aging change.The area of tooth wear has symmetry of both up,down,left and right,but the wear area of the lower front teeth is smaller than that of the upper front teeth.The overall abrasion area of Class 2 is relatively large.For the wear area of different tooth positions,it can be seen that the wear area of the canine has the largest proportion,followed by molars,incisors and premolars.(2)The ANB angle is positively related to the total wear area and the average wear area of the front and rear teeth.The larger the angle,the larger the wear area can be found;M P-FH(FMA)and FH-Mx Occ Plane are negatively related to the ratio of the wear area of the front to rear teeth.It indicates that the larger the angle of the mandible,or the steeper the occlusal plane,the wear of the posterior teeth would be more obvious;FMIA is conversely related to the average wear area of the posterior teeth.It was also found that-FH(FMA)is inversely related to the anterior tooth wear area,suggesting that the larger the mandibular angle,the smaller the anterior tooth wear.