Does the trimline extension and attachment size affect maxillary arch expansion in clear aligner therapy ? A finite element study

Karsli, Nurver; Yildirim, Fazilet; Dingiloğlu, Arda; Özsoy, Ömür Polat

doi:10.2478/aoj-2024-0014

Figures & Tables

Different components of the finite element model.

Clear aligner deformation. (A) Low and flat trimline aligner, and no attachment; (B) Low and flat trimline aligner, and 3 mm horizontal rectangular attachment; (C) Low and flat trimline aligner, and 4 mm horizontal rectangular attachment; (D) High and flat trimline aligner, and no attachment; (E) High and flat trimline aligner, and 3 mm horizontal rectangular attachment; (F) High and flat trimline aligner, and 4 mm horizontal rectangular attachment.

Total tooth displacement. (A) Low and flat trimline aligner, and no attachment; (B) Low and flat trimline aligner, and 3 mm horizontal rectangular attachment; (C) Low and flat trimline aligner, and 4 mm horizontal rectangular attachment; (D) High and flat trimline aligner, and no attachment; (E) High and flat trimline aligner, and 3 mm horizontal rectangular attachment; (F) High and flat trimline aligner, and 4 mm horizontal rectangular attachment.

Three-dimensional displacement tendency of the maxillary first and second molars in low and flat trimline aligner (LTLA) models. No attachment: (A) Displacement along the x-axis; (B) Displacement along the y-axis; (C) Displacement along the z-axis; 3 mm horizontal rectangular attachment: (D) Displacement along the x-axis; (E) Displacement along the y-axis; (F) Displacement along the z-axis; 3 mm horizontal rectangular attachment: (G) Displacement along the x-axis; (H) Displacement along the y-axis; (I) Displacement along the z-axis.

Three-dimensional displacement tendency of the maxillary first and second molars in high and flat trimline aligner (HTLA) models. No attachment: (A) Displacement along the x-axis; (B) Displacement along the y-axis; (C) Displacement along the z-axis; 3 mm horizontal rectangular attachment: (D) Displacement along the x-axis; (E) Displacement along the y-axis; (F) Displacement along the z-axis; 3 mm horizontal rectangular attachment: (G) Displacement along the x-axis; (H) Displacement along the y-axis; (I) Displacement along the z-axis.

Stress distribution in periodontal ligament. (A) Low and flat trimline aligner, and no attachment; (B) Low and flat trimline aligner, and 3 mm horizontal rectangular attachment; (C) Low and flat trimline aligner, and 4 mm horizontal rectangular attachment; (D) High and flat trimline aligner, and no attachment; (E) High and flat trimline aligner, and 3 mm horizontal rectangular attachment; (F) High and flat trimline aligner, and 4 mm horizontal rectangular attachment.

Quantity of nodes and elements within each group

Models	Model 1	Model 2	Model 3	Model 4	Model 5	Model 6
Nodes	477893	481455	482530	476430	477132	478566
Elements	1800007	1811720	1815508	1796580	1798170	1803712

Directional movements of maxillary first and second molar teeth in the X, Y, Z axes

		Measurement points		LTLA			HTLA
			X	Y	Z	X	Y	Z
Maxillary First Molar
NA	Crown	DPC	-0.42270	-0.02778	-0.05881	-0.41190	-0.02110	-0.05823
		DBC	-0.39710	-0.07859	0.09173	-0.38680	-0.07149	0.08710
		MPC	-0.38330	-0.01627	-0.07791	-0.37290	-0.00965	-0.07852
		MBC	-0.35940	-0.06824	0.07563	-0.34930	-0.06114	0.06965
	Root	PA	0.11290	0.04356	-0.09336	0.10840	0.04085	-0.09292
		DBA	0.07082	-0.01224	0.07460	0.06668	-0.01277	0.06766
		MBA	0.10520	-0.01138	0.08203	0.10130	-0.01266	0.07557
3HA	Crown	DPC	-0.42020	-0.03068	-0.05902	-0.41120	-0.02404	-0.05926
		DBC	-0.39470	-0.08151	0.09027	-0,386	-0.07477	0.08579
		MPC	-0.38070	-0.01918	-0.07690	-0.37180	-0.01252	-0.07841
		MBC	-0.35670	-0.07121	0.07534	-0.34810	-0.06442	0.06950
	Root	PA	0.11060	0.04444	-0.09261	0.10740	0.04228	-0.09314
		DBA	0.06857	-0.01199	0.07350	0.06574	-0.01223	0.06663
		MBA	0.10310	-0.01116	0.08191	0.10070	-0.01216	0.07562
4HA	Crown	DPC	-0.41860	-0.03122	-0.05910	-0.40600	-0.02346	-0.05866
		DBC	-0.39380	-0.07995	0.09021	-0.38100	-0.07342	0.08483
		MPC	-0.37950	-0.02004	-0.07719	-0.36710	-0.01211	-0.07775
		MBC	-0.35670	-0.06970	0.07430	-0.34380	-0.06302	0.06853
	Root	PA	0.11060	0.04270	-0.09291	0.10680	0.04144	-0.09225
		DBA	0.06841	-0.01112	0.07192	0.06582	-0.01213	0.06583
		MBA	0.10230	-0.01073	0.08162	0.10020	-0.01206	0.07456
Maxillary Second Molar
NA	Crown	DPC	-0.37410	-0.03655	-0.01012	-0.36120	-0.03534	-0.01292
		DBC	-0.37080	-0.06763	0.15280	-0.35810	-0.06490	0.14410
		MPC	-0.36470	-0.02798	-0.04917	-0.35240	-0.02717	-0.05065
		MBC	-0.36800	-0.06248	0.12770	-0.35570	-0.06002	0.11970
	Root	PA	0.08220	0.03165	-0.10440	0.07848	0.02973	-0.10380
		DBA	0.10000	0.01395	0.02268	0.09560	0.01288	0.01871
		MBA	0.07726	0.00664	0.04126	0.07355	0.00592	0.03650
3HA	Crown	DPC	-0.37260	-0.03812	-0.01106	-0.35920	-0.03518	-0.01297
		DBC	-0.36930	-0.06901	0.15120	-0.35620	-0.06395	0.14320
		MPC	-0.36330	-0.02969	-0.04928	-0.35080	-0.02728	-0.05048
		MBC	-0.36660	-0.06401	0.12690	-0.35430	-0.05927	0.11910
	Root	PA	0.08127	0.03206	-0.10460	0.07818	0.02935	-0.10340
		DBA	0.09893	0.01454	0.02175	0.09526	0.01302	0.01853
		MBA	0.07629	0.00712	0.04071	0.07300	0.00615	0.03625
4HA	Crown	DPC	-0.36890	-0.03773	-0.01073	-0.35850	-0.03568	-0.01303
		DBC	-0.36570	-0.06783	0.15020	-0.35530	-0.06537	0.14280
		MPC	-0.36000	-0.02954	-0.04862	-0.34950	-0.02752	-0.05014
		MBC	-0.36340	-0.06301	0.12610	-0.35260	-0.06050	0.11900
	Root	PA	0.08102	0.03158	-0.10350	0.07767	0.03027	-0.10300
		DBA	0.09858	0.01456	0.02183	0.09462	0.01331	0.01843
		MBA	0.07587	0.00726	0.04061	0.07295	0.006310	0.03632

Material properties

Material	Elastic modulus [MPa]	Poisson ratio [v]
Trabecular bone^28–30	1.37 × 10³	0.30
Cortical bone^28–30	1.37 × 10⁴	0.26
Teeth^28–30	1.96 × 10⁴	0.30
PDL^28–30	6.9 × 10^-1	0.45
Attachments^28–30	1.25 × 10⁴	0.36
CA^28,29	5.28 × 10²	0.36

Maximum aligner deformation and location

Models	Maximum deformation (mm)	Maximum deformation location
LTLA-NA	0.4209	Occlusal surface of the second molar
LTLA-3HA	0.4207	Occlusal surface of the second molar
LTLA-4HA	0.4204	Occlusal surface of the second molar
HTLA-NA	0.4121	Occlusal surface of the second molar
HTLA-3HA	0.4119	Occlusal surface of the second molar
HTLA-4HA	0.4116	Occlusal surface of the second molar

Does the trimline extension and attachment size affect maxillary arch expansion in clear aligner therapy ? A finite element study

Figures & Tables

Figure. 1

Figure. 2

Figure. 3

Figure. 4

Figure. 5

Figure. 6

Figure. 7

Quantity of nodes and elements within each group

Directional movements of maxillary first and second molar teeth in the X, Y, Z axes

Material properties

Maximum aligner deformation and location

Paradigm

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