Lateral Cephalometric Headfilms Research Articles

Multivariate prediction of skeletal Class II growth

Prediction of craniofacial growth is one of the keys to successful orthodontic treatment and stability. Despite numerous attempts at growth forecasting, our ability to accurately predict growth is limited. The present study outlines a possible new approach to prediction of craniofacial growth that differs from any previous attempt because of both the methods used and type of patients studied. The purpose of this study is to create and test prediction equations for forecasting favorable or unfavorable patterns of growth in skeletal Class II preadolescents. The subjects for this study include 19 females and 12 males from the Bolton growth center in Cleveland, Ohio. The patients were all untreated orthodontically, had lateral cephalometric headfilms taken biannually from the ages of 6 through 18 and had a Class II skeletal relationship at age 8. Twenty-six skeletal and dental landmarks were identified and digitized, and 48 linear, angular, and proportional measurements were calculated. The subjects were divided into two groups based on anterior-posterior changes in the relationship between the maxilla and mandible. Eleven patients were in the favorable growth group, with an average improvement of 4.13° in the ANB angle; 20 patients were in the unfavorable growth group with an average increase of 0.16° in the ANB angle. The following prediction formula was created with Bayes theorem and assuming a multivariate Gaussian distribution: P(Good | Fn) = ke −(0.5) | F n − μ ng | Σ g −1 | F n − μ ng | T The equation's sensitivity and specificity was calculated from serial cephalometric data from ages 6, 8, 10, and 12. The results obtained with this equation indicate 82.2% sensitivity, 95% specificity with a overall positive predictive value of 91%. This corresponds to 17.8% of patients being incorrectly identified as Poor Growers and only 5% of our patients were incorrectly identified as Good Growers. We conclude that this prediction formula improves the ability to predict favorable or unfavorable patterns of growth in this sample of skeletal Class II preadolescents. (Am J Orthod Dentofacial Orthop 1998;114:283-91.)

A study on the pharyngeal size in different skeletal patterns

In the present study, pharyngeal size was investigated on the lateral cephalometric head films of 90 subjects, 45 males and 45 females, having different ANB angles. All of the subjects were aged 13 to 15 years. The films were taken at natural head position, and all were divided into three groups according to the ANB angle: ANB angles smaller than 1°, between 1° and 5°, and larger than 5°. In addition, each group was also divided into two subgroups according to sex. The effects of the ANB angle and sex on the pharyngeal size were investigated by means of variance analysis. It has been observed that two measurements, hy-apw4 and oropharynx area measurements, were affected by the change of ANB angle, and two other measurements, t-ppw and hy-apw2 measurements, by the sex; and that hy-apw4 measurement and oropharynx area became smaller with the increase of ANB angle. (A M J O RTHOD D ENTOFAC O RTHOP 1995;108:69-75.)

Quantification of function regulator therapy using elliptical Fourier functions.

The application of various functional appliances to correct antero-posterior skeletal discrepancies in the treatment of Class III malocclusion has received increased attention. In this context, elliptical Fourier functions (EFF) are particularly useful for eliciting boundary-outline information. This longitudinal study was undertaken to visually and numerically describe the shape alterations arising as a response to treatment with the FR-3 appliance of Fränkel. The subjects chosen were Caucasians (n = 14) from the Glasgow Dental Hospital and School who presented with Class III incisor relationships. Lateral cephalometric head-films were available prior to the initiation of treatment, at the end of active treatment, and at least one year out of retention. Maxillary and mandibular boundary outlines were carefully traced. A set of points, 42 on the maxilla, and 78 on the mandible, were precisely located. These points were then digitized and used to compute EFF's with 20 harmonics. These equations were then standardized for size. Subsequently, 102 maxillary and 150 mandibular closely spaced points on the outline were calculated from the EFF's. After superimposition on the centroid, expected vectors were then computed to these points from the centroid. Statistically significant dento-alveolar shape changes could be discerned with treatment. These involved a localized anterior repositioning of the maxillary incisal aspect with a concomitant posterior displacement of the mandibular incisal aspect. There was no evidence of shape changes in the basal areas of either the maxilla or mandible. This method of fitting Fourier descriptors, specifically EFF's, provides a precise numerical and visual description of the changes arising from functional regulator therapy.

Long-term effects of chincap therapy on skeletal profile in mandibular prognathism

The purpose of this study was to investigate the long-term changes in the skeletal Class III profile subsequent to chincap therapy. The sample consisted of 63 Japanese girls who had skeletal Class III malocclusions before treatment. All underwent chincap therapy from the beginning of treatment. The duration of chincap therapy varied but averaged 4 1/2 years. The samples were divided into the following three groups according to their ages when chincap therapy was started: A group that started at 7 years of age (n = 23), a group that started at 9 years of age (n = 20), and one that started at 11 years of age (n = 20). The data were derived from lateral cephalometric head films, taken serially at the ages of 7, 9, 11, 14, and 17 years. Skeletal facial diagrams were constructed by X-Y coordinates of representative cephalometric landmarks. The data were analyzed statistically. The results of the present study were as follows: (1) The mandible showed no forward growth during the initial stages of chincap treatment in all three groups. (2) Patients who had entered treatment at 7 and 9 years of age appeared to show a catch-up manner of mandibular displacement in a forward and downward direction before growth was completed. (3) There was no statistical difference in the final skeletal profile between the group that had entered treatment at age 7 and the one that had entered at age 11. In conclusion, the skeletal profile was greatly improved during the initial stages of chincap therapy, but such changes were often not maintained thereafter. This finding indicated that chincap therapy did not necessarily guarantee positive correction of skeletal profile after complete growth.

Facial growth subsequent to Le Fort I osteotomies in adolescent monkeys

The study goal was to assess qualitatively and quantitatively the craniofacial adaptations following total maxillary osteotomy with and without mandibular autorotation. Six adolescent female Macaca fascicularis monkeys were randomly divided into two surgical groups, and eight others served control. Prior to surgery, metallic implants were inserted in the anterior part of the cranial base, on opposite sides of craniofacial sutures, and in multiple sites of the maxilla and mandible. Group I animals underwent a Le Fort I advancement of 4 mm, while Group II animals had a 5-mm advancement and a 2.5-mm impaction. Lateral cephalometric headfilms were taken at monthly intervals for a total follow-up of 12 months after surgery. At least two cephalograms were taken on each occasion, one with the teeth in occlusion and the other with the mouth wide open. The latter was used to ascertain accurately the outline of the mandibular condyle. Cephalometric superimposition methods were used to quantify the growth changes. The findings indicated that the growth changes in the maxilla and mandible were related to the extent of injury caused by maxillary surgery. The largest increments and rates of growth were observed respectively in the control animals, Group I animals (anterior maxillary repositioning), and Group II animals (anterior and superior maxillary repositioning). The most interesting finding was that mandibular growth pattern followed maxillary growth pattern in both experimental groups, and the immediate postsurgical occlusion in Class II molar relationship was maintained with increased overjet in both experimental groups throughout the postsurgical observation period.

Increase in mandibular and chin projection with orthognathic surgery

Three groups of twelve patients, each of whom had a Class II, Division 1 malocclusion with a markedly convex facial profile and steep mandibular plane, were treated by orthodontic means and orthognathic surgery. One group had mandibular advancement, another had maxillary elevation, and the third had both surgical procedures combined, with genioplasties performed in some cases from each group. Changes were studied with the aid of lateral cephalometric headfilms taken just after surgery and from 5 to 105 months later. Horizontal changes in point B and pogonion after the follow-up period were 7.0 mm and 8.5 mm with mandibular surgery, 5.4 mm and 9.3 mm with maxillary surgery, and 10.7 mm and 16.4 mm with combined surgery. The amount of change is much larger than found with orthodontic or orthopedic treatment alone and makes possible the successful treatment of very difficult problems.

The influence of lip thickness and strain on upper lip response to incisor retraction

Placement of teeth according to accepted cephalometric criteria does not necessarily ensure that overlying soft tissue will drape in a harmonious manner. The purpose of this research was to investigate the influence of maxillary lip thickness and lip strain on the relationship between dental and integumental tissue changes in orthodontically treated patients. Data were derived from pretreatment and retention lateral cephalometric head films of forty Caucasian subjects with Class II, Division 1 malocclusions. All patients were treated with edgewise appliances. Percentile groups were created for males and females according to the magnitude of maxillary lip thickness and lip strain. It was found that there was significant correlation between osseous changes and soft-tissue changes in both males (r = 0.83, p < 0.01) and females (r = 0.85, p < 0.01). Strong correlations were found between osseous changes and soft-tissue changes in subjects with thin lips (males, r = 0.92, p < 0.01; females, r = 0.98, p < 0.01), whereas no significant correlations were found in subjects with thick lips. Significant correlations were found between incisor changes and vermilion border changes in males (r = 0.61, p < 0.01) and females (r = 0.51, p < 0.05). Correlations were strong between incisor changes and vermilion border changes in subjects with high lip strain (males, r = 0.92, p < 0.01; females, r = 0.82, p < 0.05) but were insignificant in subjects with low lip strain.

The biologic significance of the divine proportion and Fibonacci series

This article shows the application of basic mathematical and geometric principles to the normal morphology of structures regularly involved in orthodontics and dentistry. For appreciation of beauty, it has been suggested that the human mind functions at the limbic level in attraction to proportions in harmony with the Golden Section. This is a proportion of 1.618 and its reciprocal 0.618 in geometry. Fibonacci numbers express precisely the same ratio and are mathematically unique and mysterious. Questions arose regarding these geometric and mathematical relationships in our living patients. Studies were conducted from measurements of models of the teeth of normal-occlusion subjects, the photographs of the faces of commercial models, and conditions found in lateral and frontal cephalometric head films. Variations of the beautiful photographic models were analyzed together with computerized composites of patients with ideal occlusions. Several key relationships were found. The investigation yielded useful relationships for all aspects of dentistry and particularly for orthodontics and orthognathic surgery. The normal face and the occlusion of the teeth have a majestic beauty. The study strongly suggests that esthetics can indeed be made scientific rather than the need to resort to subjective perceptions as in the past.

Studies Leading to the Practice of Abortion of Lower Third Molars

Studies Leading to the Practice of Abortion of Lower Third Molars

The craniofacial skeletal pattern of the South African Negro

Lateral cephalometric head film measurements on twenty-seven male and twenty-eight female adult craniums and mandibles with excellent occlusions were compared with similar measurements on Caucasoids with excellent occlusions. Among the differences between the two groups is the forward position of the short maxilla relative to the anterior cranial base in the South African Negro. The forward location of point A has been effect of increasing the ANB angle, since the relative position of point B in both groups is much the same. Unlike the American Negro, the labial inclination of the upper incisors in the South African Negro is not pronounced but is similar to the inclination observed in Caucasoids. Because of the large ANB angle, the lower incisors in the S.A. Negro (as in the American Negro) are severely labially inclined. Ramus height in the S.A. Negro is shorter than that of Caucasoids and appears to be related to the steep mandibular plane observed in the former population group.

The craniofacial pattern of the Lengua Indians of Paraguay

Lateral cephalometric headfilms of 30 male and 30 female Lengua Indians taken in the Chaco area of Paraguay were compared with a sample of 23 male and 25 female South African Caucasoids with excellent occlusion. The most obvious difference noted between the two population groups was the degree of prognathism evident in the Lengua. This was attributed to the generally shorter anterior cranial base in the latter group rather than to the size or forward positioning of their jaws. The significantly larger ANB (Subspinale, Nasion, Supramentale) angle observed in the Lengua was attributed to one or both of two factors, namely, the short anterior cranial base or the clockwise rotation (forward tipping) of the jaws relative to the anterior cranial base. Chinpoint position relative to the anterior cranial base in the Lengua is not much different from that of our Caucasoid sample. The lower incisor teeth in the Lengua, but not the upper ones, are more labially inclined than those of the Caucasoids.

Prediction of abnormal growth in Class III malocclusions

Four significant factors have been identified in the lateral cephalometric head film which would indicate the likelihood of the patient growing in an abnormal Class III manner. The normal person grows approximately the same amount from basion to nasion as he does on the corpus axis of the mandible. The abnormal Class III syndrome grows greater increments on the mandible than at the cranial base. For the purpose of determining the accuracy of computer prediction of abnormal growth, fourteen skeletal Class III cases were selected from the files of the Hokkaido University Orthodontic Department. A significant relationship was shown between abnormal growth and the sum of the standard deviations from the normal of the four cephalometric “predictor measurements”. These data would give the clinician insight as to which patients might require early orthopedic treatment (chin cup), conventional orthodontic treatment, or surgical orthodontic correction after growth is complete. This is the first published demonstration of computerized cephalometric methods showing the ability to distinguish between normal and abnormal growth in a particular patient type. It is hoped that, through the comparison of thousands of predictions with actual data, more recognizable abnormal growth patterns will appear in the future.

An evaluation of extraoral combined high-pull traction and cervical traction to the maxilla

The effects of extraoral combined high-pull traction and cervical traction of known duration (mean, 122 days) and magnitude (2.5 to 3 pounds total per side) were studied by means of serial lateral cephalometric head films of thirty patients. The lateral cephalometric head films used were taken at three different times: before the extraoral force was applied, after the prescribed period of continuous headgear wear, and as long as possible after the extraoral force was discontinued. Changes in the dentition and associated structures were described both for the period of continuous headgear wear and for an average of 3.2 years later. The following conclusions are based on statistical analysis of the observed changes: 1. The position of the maxilla and the palatal plane was not significantly affected by relatively short periods of extraoral combined high-pull traction and cervical traction to the maxillary first molars as used for this investigation. 2. The maxillary first molars can be moved distally and bodily with this appliance without extrusion. 3. On the average, the mandibular first molars uprighted distally in response to the extraoral force to the maxilla. 4. The maxillary and mandibular first molars demonstrated a strong tendency to recover to their original positions and inclinations relative to their respective bases during the posttreatment period. 5. The amount and direction of growth in the posttreatment period may be important in determining how the Class I relationship is maintained.

The “Wits” appraisal of jaw disharmony

The “Wits” appraisal of jaw disharmony is a simple method whereby the severity or degree of anteroposterior jaw dysplasia may be measured on a lateral cephalometric head film. The method entails drawing perpendiculars from points A and B on the maxilla and mandible, respectively, onto the occlusal plane. The points of contact of the perpendiculars onto the occlusal plane are labeled AO and BO, respectively. In a sample of twenty-one male and twenty-five female adults selected on the basis of excellence of occlusion, it was found, on the average, that in females points AO and BO coincided and in males point BO was located 1 mm. ahead of point AO. In skeletal Class II jaw dysplasias, point BO would be positioned well behind point AO (positive reading), whereas in Class III skeletal jaw disharmonies, the “Wits” reading would be negative, that is, with point BO ahead of point AO. The advantages of the “Wits” appraisal over that of the conventional ANB angle reading are illustrated and discussed.