molar_protraction[1] (1) (1) (1).pptxxxxxxxxxxxx

molar protraction

1. Factors associated with spontaneous mesialization of impacted mandibular third molars after second molar protraction DR PRIYA KAWANA PG STUDENT DEPT OF ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS Baik UB, Kang JH, Lee UL, Vaid NR, Kim YJ, Lee DY. Factors associated with spontaneous mesialization of impacted mandibular third molars after second molar protraction. Angle Orthod . 2020 Mar;90(2):181-186.

2. Contents Introduction Material and method Statistical Analysis Results Discussion limitation Conclusions Cross References References References

3. Introduction Protraction of molars is easier in the maxilla than in the mandible owing to the relative abundance of trabecular bone in the former. If the molars are to be moved along a continuous archwire , a 0.016 X 0.022-inch or 0.017 X 0.025-inch SS wire (in 0.018-inch slots) is recommended to avoid mesial tipping and undesired retraction of the anterior teeth. Biomechanics in orthodontics principle and practice , Ram s. nanda , Yahya s tosun

4. The prevalence of missing mandibular molars and premolars is high because they are frequently extracted due to caries Using temporary anchorage devices (TADs), the molars could be more easily protracted Biomechanics in orthodontics principle and practice , Ram s. nanda , Yahya s tosun

5. IP Indian Journal of Orthodontics and Dentofacial Research 2020;6(4):229–235

6. In patients whose second molars were protracted to replace the missing posterior teeth reported that third molars had an increased tendency of spontaneous uprighting in the greater Nolla stage and those that erupted faster. Baik UB, Bayome M, Abbas NH, Park JH, Lee UL, Kim YJ. Factors associated with spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction. Am J Orthod Dentofacial Orthop . 2019; 156:178–185

7. Aim The purpose of this study was to investigate factors related to the spontaneous mesialization of impacted third molars after mandibular second molar protraction to close the space caused by missing L-6 and L-E by using TADs.

8. This retrospective clinical study was approved by the institutional review board of Korea University Anam Hospital To calibrate linear measurements, magnification of the panoramic radiograph was calculated by measuring the mesiodistal width of the mandibular second molar on the diagnostic model and panoramic radiograph of each patient Material and method

9. Inclusion criteria 1) Missing l-6 or l-e 2) Impacted mandibular third molars at the pretreatment time point (t1) 3) Space caused by missing l-6 or l-e that had been closed by second molar protraction using tads 4) Second molar roots parallel with the adjacent teeth at the time of space closure. Exclusion criteria Fully or partially erupted third molar at the start of treatment Malformation of the impacted third molar Orthodontic brackets bonded to the third molar during second molar protraction.

10. Nolla’s developmental stage of the third molar was assessed at T1 and T2. Radiographs were reexamined by the same investigator ( Dr Kang) 4 weeks after the first examination. Nolla CM. The development of permanent teeth. J Dent Child. 1960;27:254–266

11. Statistical evaluations Statistical evaluations were performed using SPSS software for Windows (version 20.0, IBM Corp, Armonk, NY). The Mann-Whitney U test was used to evaluate the difference in characteristics between male and female patients. The Fisher’s exact test was used to determine the difference in distribution of the missing tooth (L-6 or L-E) according to sex. The paired t-test was used to assess differences in the study variables between T1 and T2

12. Result

13. Discussion second molar protraction is favorable after eruption and spontaneous mesialization of third molars . The mean ratio of third molar mesialization to second molar protraction of 0.8 +/- 0.3 ( n=43, 86%) showed full spontaneous mesialization , (n = 7, 14%) showed limited or almost no mesial movement. . Baik UB. Molar protraction and uprighting (2nd molar protraction in the 1st molar missing site and uprighting an impacted 3rd molar). APOS Trends in Orthodontics. 2018;8: 57–63

14. These third molars were not ankylosed as they showed vertical eruption but lacked spontaneous mesial movement and required active protraction using a fixed appliance More developed third molars showed greater spontaneous mesialization . The mean Nolla’s stage of third molars in patients showing complete mesialization at T1 was 7.2 +/- 2.0 incomplete mesialization , it was 5.4 +/- 3.2 Marks SC Jr , Schroeder HE. Tooth eruption: theories and facts. Anat Rec. 1996;245:374–393

15. Third molars located close to the occlusal plane showed a tendency for a greater amount of mesialization The mean third molar angulation (8 MP) showed no significant changes from T1 to T2, but the change in third molar angulation from T1 to T2 (D8MP) showed a high range from –36.88 to 32.7, indicating great variability in angulation changes during eruption and mesialization .

16. Third molars that showed mesial tipping as a result of second molar protraction mainly exhibited crown mesialization only and lacked true bodily mesial movement; orthodontic uprighting was required after second molar protraction using fixed appliances.

17. Limitations The panoramic radiographs were used. Linear and angular measurements acquired from panoramic radiographs have been reported to be reliable inherent errors due to image distortion may still have been present , especially in the horizontal dimensions A second limitation was that the horizontal position of the third molar was analyzed at the end of second molar protraction

18. Conclusion When Nolla’s stage of the third molar was higher before treatment and when the second molar protraction time was longer show greater third molar mesialization When mandibular second molars were protracted to close the missing space of L-6 or L-E, impacted mandibular third molars showed varying amounts of spontaneous mesialization . The amount of third molar mesialization were not associated with Patient’s age, sex, and initial angulation of the third molar

19. Cross references 1 Un-bong baik,a mohamed bayome,b,c noha hussein abbas,d jae hyun park,e ui-lyong lee,f and yoon-ji kim,factors associated with spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction, am j orthod dentofacial orthop 2019;156:178-85 Conclusions : available space for third molar eruption before and after second molar protraction is not associated with uprighting of erupting third molars. Older patients whose third molars are in greater nolla stage, are in a more upright position at T1, and have a greater eruption rate have a greater chance for third molar uprighting . Alternatively, an increase in second molar protraction rate results in mesial tipping of the third molars

20. Cross references 2 Baik UB, Kook YA, Bayome M, Park JU, Park JH. Vertical eruption patterns of impacted mandibular third molars after the mesialization of second molars using miniscrews . Angle Orthod . 2016 Jul;86(4):565-70.. Aim:- factors affect the vertical eruption of impacted third molars when space caused by missing molars is successfully closed by mesialization of the second molar using miniscrews . Conclusions:  Impacted mandibular third molars vertically erupt as a result of uprighting with mesialization of the second molar, and vertical eruption is affected by the initial vertical location of impacted third molars and available space.

21. References Baik UB, Kang JH, Lee UL, Vaid NR, Kim YJ, Lee DY. Factors associated with spontaneous mesialization of impacted mandibular third molars after second molar protraction. Angle Orthod . 2020 Mar;90(2):181-186. Baik UB, Chun YS, Jung MH, Sugawara J. Protraction of mandibular second and third molars into missing first molar spaces for a patient with an anterior open bite and anterior spacing. Am J Orthod Dentofacial Orthop . 2012 Jun;141(6):783-95 Baik UB, Kook YA, Bayome M, Park JU, Park JH. Vertical eruption patterns of impacted mandibular third molars after the mesialization of second molars using miniscrews . Angle Orthod . 2016 Jul;86(4):565-70. . Biomechanics in orthodontics principle and practice , Ram s. nanda , Yahya s tosun Baik UB, Bayome M, Abbas NH, Park JH, Lee UL, Kim YJ. Factors associated with spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction. Am J Orthod Dentofacial Orthop . 2019; 156:178–185

22. Nolla CM. The development of permanent teeth. J Dent Child. 1960;27:254–266 Baik UB. Molar protraction and uprighting (2nd molar protraction in the 1st molar missing site and uprighting an impacted 3rd molar). APOS Trends in Orthodontics. 2018;8: 57–63 Marks SC Jr , Schroeder HE. Tooth eruption: theories and facts. Anat Rec. 1996;245:374–393 IP Indian Journal of Orthodontics and Dentofacial Research 2020;6(4):229–235

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