Reliability of torque expression by the Invisalign® appliance: A retrospective study

Gaddam, Raj; Freer, Elissa; Kerr, Brett; Weir, Tony

doi:10.21307/aoj-2021-001

Figures & Tables

Best-fit superimposition (global and fine).

The best fit superimposition with a common transverse reference plane for both pretreatment and predicted post-treatment STL files.

Box-whisker plot showing the distribution of torque and IIA differential.

Mean accuracy of the torque expression and interincisal angle change resulting from prescribed torque.

Calculation of torque, interincisal angle (IIA) differential and mean accuracy_

Predicted change in torque = torque at T1 – torque at T0Achieved change in torque = torque at R – torque at T0Torque differential = predicted change in torque – achieved change in torque

Predicted change in IIA = IIA at T1 – IIA at T0Achieved change in IIA = IIA at R – IIA at T0IIA differential = predicted change in IIA – achieved change in IIA

Mean accuracy for torque or IIA = 100 – (predicted change-achieved change/predicted change) X 100

Criteria for sample selection_

Inclusion criteria: Non-growing patientsComplete permanent dentitionOrthodontic treatment with Invisalign (SmartTrack)All subjects finished the initial aligner wear as determined by ClinCheckTwo-week aligner wear protocolSimple Class I malocclusion comprising spacing (< 4 mm) to crowding (< 6 mm)Non – extraction treatmentNo interproximal reductionNo intermaxillary elasticsNo orthognathic surgeryNo restorative treatment to incisors and distal most molars during orthodontic treatmentAll the subjects included in this study met the criteria of compliance

Exclusion criteria:Periodontally compromised patientsMedications which alter bone metabolism (e.g.: Bisphosphonates, PG inhibitors)Patients treated with Power Ridges

Descriptive statistics and paired student t-test values for torque, IIA differential_

Group		N	Predicted change (Mean ± SD) (°)	Achieved change (Mean ± SD) (°)(Mean ± SD) (°)	Differential (predicted change – achieved change) (°)			t	P-value
					Median (°)	95% CI
						Lower (°)	Upper (°)
Labial CT	UC	56	8.16 ± 7.78	1.73 ± 5.22		6.43 ± 7.09	5.94	4.50	8.36	6.78	<0.001*
	UL	51	5.99 ± 6.26	0.93 ± 4.49	5.06 ± 7.32	3.94	2.96	7.16	4.94	<0.001*
	LI	112	7.77 ± 5.11	5.03 ± 5.94	2.75 ± 5.70	2.40	1.65	3.84	5.10	<0.001*
Lingual/Palatal CT	UC	24	4.49 ± 3.38	5.22 ± 4.01	-0.73 ± 3.31	-0.71	-2.16	0.70	-1.08	>0.05
	UL	29	4.90 ± 4.28	4.54 ± 4.38	0.36 ± 4.41	0.81	-1.36	2.08	0.44	>0.05
	LI	48	4.73 ± 5.39	5.40 ± 5.50	-0.67 ± 6.06	-0.45	-2.49	1.15	-0.77	>0.05
Labial CT – IIA		61	13.80 ± 10.69	4.80 ± 8.74	9.00 ± 10.73	7.50	6.20	11.8	6.55	<0.001*
Lingual/Palatal CT– IIA		19	9.79 ± 11.70	13.20 ± 9.44	-3.40 ± 7.90	-2.45	-7.39	0.59	-1.88	>0.05

Liner regression analysis_

Group		Unstandardised coefficients		Standardised coefficients
Group		Constant	B	(R ²)
Labial CT	UC	-2.27	0.49	0.53
	UL	-1.21	0.36	0.25
	LI	-2.21	0.93	0.64
Lingual/Palatal CT	UC	1.18	0.90	0.58
	UL	1.33	0.66	0.41
	LI	1.76	0.77	0.57
Labial CT – IIA		-3.08	0.57	0.49
Lingual/Palatal CT – IIA		6.39	0.70	0.74

Reliability of torque expression by the Invisalign® appliance: A retrospective study

Figures & Tables

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Calculation of torque, interincisal angle (IIA) differential and mean accuracy_

Criteria for sample selection_

Descriptive statistics and paired student t-test values for torque, IIA differential_

Liner regression analysis_

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