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W Hussels

Publications and source records attributed to W Hussels.

4 recordsLinked to original sources
PubMed1987

Clinical application of a method to correct angle ANB for geometric effects.

Angle ANB does not provide an adequate assessment of the skeletal discrepancy between the jaws in the sagittal plane. Attempts have been made to avoid the fallacies with the introduction of quadrilateral and Wits analyses. Based on the Wits appraisal of zero, Hussels and Nanda (1984) were able to evaluate and eliminate four geometric factors that affect angle ANB. These four factors are (1) anteroposterior position of point N in relation to points A and B, (2) inclination of the occlusal plane, (3) dental height (a linear measurement between point A and B), and (4) distance between points N and B. The authors derived a mathematic formula to evaluate the influence of all four parameters in terms of angle ANB. This formula reflects the skeletal relationship of a patient when points A and B are on a perpendicular plane in relation to the occlusal plane (Wits = 0 mm). The authors define this to be a Class I skeletal relationship. A comparison of the measured ANB angle with the calculated angle ANB gives a better perspective of the skeletal discrepancy. If the measured angle ANB is larger than the calculated angle, the discrepancy is Class II. On the other hand, if the measured angle ANB is smaller than the calculated angle, the skeletal relation is Class III. This method of assessing the skeletal sagittal position of the jaws in relation to each other was applied to 508 patients. The authors showed that the geometric influence of the four factors indeed conceals the true skeletal relations when angle ANB is used without any correction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Effect of maxillary incisor angulation and inclination on arch length.

This article discusses the quantitative effects of angulation of incisors on dental arch length. The incisors are approximated mathematically to rectangular shapes, which enables the authors to calculate the change in arch length when teeth are tipped and to describe graphically the effect of other influencing parameters. The authors demonstrate that the height and the width of a tooth crown can enhance or diminish the effect of angulation on arch length. In addition to angulation, dental arch length is also influenced by torque. A mathematic formula has been derived and the results are demonstrated numerically and graphically. The authors show that vertical positioning of the brackets plays an important role because torquing is a rotational movement around the center of the bracket slot. Hence, in calculating the effect of torque on dental arch length, one must consider different angles and axes than those discussed by Andrews.4 The interaction between angulation and inclination and its influence on dental arch length has been investigated. It has been found to cause little change in arch length.

Cephalometry↗
PubMed1984

Analysis of factors affecting angle ANB.

Cephalometric analyses based on angular and linear measurements have obvious fallacies, which have been discussed in detail by Moyers and Bookstein. However, the clinical application of such an analysis by the orthodontic profession in treatment planning is widely accepted. Variations of angle ANB are commonly used to determine relative jaw relationships in most of the cephalometric evaluations. Several authors, including points A and B influences angle ANB, as does rotational growth of the upper and lower jaws. In addition, the authors point out that growth in a vertical direction (distance N to B) and an increase of the dental height (distance A to B) may contribute to changes in angle ANB. For a Class I relation (Wits = 0 mm), a mathematical formula has been developed which enables the authors to study the geometric influence of angle ANB caused by the following four effects: (1) rotation of the jaws and/or occlusal plane relative to the anterior cranial base; (2) anteroposterior position of N relative to point B, (3) vertical growth (distance N to B); (4) increase in dental height (distance A to B). It was observed that, contrary to the common belief that an ANB angle of 2 +/- 3.0 degrees is considered normal for a skeletal Class I relation, the calculated values of angle ANB will vary widely with changes in these four controlling factors under the same skeletal Class I conditions (Wits = 0 mm). Therefore, in a case under consideration, angle ANB must be corrected for these geometric effects in order to get a proper perspective of the skeletal discrepancy. This is facilitated by comparing the measured ANB angle with the corresponding ANB angle calculated by a formula for a Class I relationship. The corresponding calculated angle ANB can be taken from the tables which are based upon the formula using the same values for SNB, omega (angle between occlusal plane and anterior cranial base), b (which is distance N to B) and a (dental height measured as perpendicular distance A to occlusal plane plus perpendicular distance occlusal plane to B). The difference between actual and calculated angle ANB is a measurement of the severity of the skeletal discrepancy. This leads to a new definition of what denotes skeletal Class II and III relationships, since and angle ANB calculated for a skeletal Class I (Wits = 0 mm) can vary widely and can be either negative or positive.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗