The Third-Order Angle and the Maxillary Incisor's Inclination to the NA Line

Knösel, Michael; Kubein-Meesenburg, Dietmar; Sadat-Khonsari, Reza

doi:10.2319/112405-412r.1

Cited by 11 publications

(11 citation statements)

References 27 publications

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“…Third-order prescriptions of straightwire brackets refer to the occlusal plane perpendicular (OPP), which does not coincide with these common cephalometric reference lines. The deviation between 3 rd -order angles and cephalometric incisor inclination has been described previously 21,22 . Although the findings of these studies may be of value in cases where there is almost a straight crown-root relation, it is conjectural whether they would also apply to subjects with distinctly reduced CRA, since investigations on Class II division 2 subjects have indicated a considerable variation in CRA 17,18,23 ( Figure 2).…”

Section: Hard Tissue Bordersmentioning

confidence: 99%

“…Third order angles ( Figure 3) were derived from dental cast pairs which were made at the same time as the corresponding lateral radiograph. The method used incorporates a type of incisor inclination gauge whose reliability has been proven in several studies already [21][22] . The upper right central incisor was chosen and prepared for assessment by marking the longitudinal axis point of the clinical crown, LACC.…”

Section: Third Order Measurementsmentioning

confidence: 99%

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On the Interaction between Incisor Crown-Root Morphology and Third-Order Angulation

Knösel¹,

Jung²,

Attin³

et al. 2009

Angle Orthod

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OBJECTIVE: To evaluate the significance of crown-root angles (CRAs) by testing the null hypothesis that there are no significant differences in deviations of third-order angles to axial inclination values between Angle Class II division 2 incisors and a neutral occlusion control sample. MATERIALS AND METHODS: The study group comprised n(total) = 130 whites with either Angle Class II division 2 (n(1) = 62; group A) or neutral (n(2) = 68; control group B) occlusal relationships. Upper central incisor inclination (U1) was assessed with reference to the cephalometric lines NA and palatal plane (U1NA/deg, U1PP/deg). Craniofacial sagittal and vertical relations were classified using angles SNA, SNB, ANB, and NSL-PP. Third-order angles were derived from corresponding dental cast pairs using an incisor inclination gauge. Welch's two-sample t-tests (alpha-level: .05) were used to test the null hypothesis. Single linear regression was applied to determine third-order angle values as a function of axial inclination values (U1NA, U1PP) or sagittal craniofacial structures (ANB angle), separately for group A and B. RESULTS: The discrepancy between axial inclination (U1NA, U1PP) and third-order angles is significantly different (P < .001) between groups A and B. Regression analysis revealed a simply moderate correlation between third-order measurements and axial inclinations or sagittal craniofacial structures. CONCLUSION: The hypothesis is rejected. The results of this study warn against the use of identical third-order angles irrespective of diminished CRAs typical for Angle Class II division 2 subjects. Routine CRA assessment may be considered in orthodontic treatment planning of Angle Class II division 2 cases. -order measurements and axial inclinations or sagittal craniofacial structures. On the Interaction between Incisor Crown-Root Conclusion:The results of this study warn against the use of identical 3 rd -order angles irrespective of diminished crown-root angles typical for Angle Class II division 2 subjects. Routine CRA assessment may be considered in orthodontic treatment planning of Angle Class II division 2 cases.

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Section: Hard Tissue Bordersmentioning

confidence: 99%

Section: Third Order Measurementsmentioning

confidence: 99%

On the Interaction between Incisor Crown-Root Morphology and Third-Order Angulation

Knösel¹,

Jung²,

Attin³

et al. 2009

Angle Orthod

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“…12,13 The most proclined upper and lower central incisors were chosen, since these are easy to observe in lateral radiographs. They were prepared for assessment by marking the midpoint of the labial enamel surface (FA point).…”

Section: Cast Measurementsmentioning

confidence: 99%

Changes in Incisor Third-Order Inclination Resulting from Vertical Variation in Lingual Bracket Placement

Knösel

Jung

Gripp-Rudolph³

et al. 2009

The Angle Orthodontist

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Objective: To test the null hypothesis that third-order measurements are not correlated to lingual incisor features seen on radiographs. Material and Methods: The lateral headfilms of 38 untreated, norm-occlusion subjects without incisor abrasions or restorations were used for third-order measurements of upper and lower central incisors and assessment of the inclination of four sites suitable for lingual bracket placement with reference to the occlusal plane perpendicular. Lingual sections were determined by the tangents at the incisal fossa (S1), at the transition plateau between incisal fossa and the cingulum (S2), by a constructed line reaching from the incisal tip to the cingulum (S3), and by a tangent at the cingulum convexity (S4). Third-order angles were also assessed on corresponding dental casts using an incisor inclination gauge. Regression analysis was performed using the third-order measurements of both methods as the dependent variables and the inclination of the lingual enamel sections (S1, S2, S3, S4) as the independent variables. Results: The null hypothesis was rejected. For the most common bracket application sites located on the lingual shovel (S1 and S2), third-order inclination changes of 0.4-0.7 degrees are expected for each degree of change in the inclination of the lingual surface. The impact of bracket placement errors on third-order angulation is similar between sections S1 and S2 and the cingulum convexity (S4). Section S3 proved to be least affected by interindividual variation. Conclusion:The third-order measurements are correlated to lingual incisor features. Accordingly, third-order changes resulting from variation in lingual bracket placement can be individually predicted from radiographic assessments. (Angle Orthod. 2009;79:747-754.)

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“…27,28 A further unwanted effect may be lingual tipping of lower molars with excessive force when non-rigid wires are in place. Elastics may favour retroclination of upper incisors and procli nation of lower incisors, leading to further reduction of the over jet.…”

Section: Fixed Functional Appliancementioning

confidence: 99%

Transferring from functional to fixed appliances

2016

Orthodontic Functional Appliances

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The Third-Order Angle and the Maxillary Incisor's Inclination to the NA Line

Cited by 11 publications

References 27 publications

On the Interaction between Incisor Crown-Root Morphology and Third-Order Angulation

On the Interaction between Incisor Crown-Root Morphology and Third-Order Angulation

Changes in Incisor Third-Order Inclination Resulting from Vertical Variation in Lingual Bracket Placement

Transferring from functional to fixed appliances

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