Prediction of mandibular growth rotation

A longitudinal cephalometric study of postorthodontic craniofacial changes

Although the orthodontist focuses great efforts on diagnosis and treatment of the patient, less attention is paid to posttreatment changes that occur because of relapse and continued growth, especially over the long term. This cephalometric study describes 36 patients who were recalled x = 5.5 years after treatment and again x = 14.4 years after treatment. Most linear dimensions increased significantly from the end of treatment to first recall (ca. 16 to 21 years), presumably as a result of continued adolescent growth, but few changes achieved significance thereafter (ca. 21 to 30 years). Arch relationships (eg, ANB, NAP, AOBO, Y-axis) continued to improve after treatment, probably as a result of late growth of the mandible producing a more orthognathic profile. There was little change from first to second recall in any of the variables. Results suggest that if relapse occurs, it is likely to be evident soon after treatment and diminish thereafter and that continued craniofacial growth generally augments the orthodontic correction.

Prediction of mandibular growth rotation: assessment of the Skieller, Björk, and Linde-Hansen method

The purpose of this investigation was to assess the method proposed by Skieller, Björk, and Linde-Hansen in 1984 to predict mandibular growth rotation. Our sample consisted of 40 randomly selected, untreated, adolescent subjects representative of the patient population generally encountered in orthodontic practice. The four independent variables identified in the Skieller study as having the highest predictive value (mandibular inclination, intermolar angle, shape of the lower border of the mandible, and inclination of the symphysis) were identified on initial lateral cephalograms. The proposed regression equations were applied and predicted mandibular rotations obtained. Final lateral cephalograms made 6 years after the initial profile radiographs were superimposed and actual mandibular rotation recorded. The observed and predicted rotations were compared and regression analyses performed to determine the amount of variability in observed values accounted for by the four variables individually and in combination. Only 5.6% of the variability in mandibular growth rotation could be accounted for using the four variables individually. Only 9% of the variability could be accounted for with a combination of the variables. In addition, we performed a Monte Carlo analysis, which mirrored the Skieller analysis but used random numbers instead of actual cephalometric data, to determine if the Skieller results may simply have capitalized on chance. Using the same forward stepwise selection procedure with a rejection level of P >.1, we found after 5000 simulations that a mean of 84% and a median of 94% of mandibular growth rotation variability could be accounted for using meaningless data in the Skieller analysis. This result was comparable to the Skieller value of 86%. In conclusion, information derived from pretreatment lateral cephalograms using the Skieller, Björk, and Linde-Hansen method does not permit clinically useful predictions to be made in a general population relative to the direction of future mandibular growth rotation.

Craniofacial growth in children treated for malignant diseases

With the improving cure rate in childhood malignancies, increasing interest has been focused on the long-term survivors of childhood cancer and the quality of their life. The severity of long-term disturbances in dental and craniofacial development is dependent on the age of the child at diagnosis, if chemotherapy is combined with radiation or not. With regard to craniofacial development combination chemotherapy has no effects compared with healthy controls, whereas children treated cranial irradiation before 5 years of age exhibit a reduced growth of the mandible. Conditioning before bone marrow transplantation with total body irradiation results in a significantly reduced growth of the craniofacial skeleton. The mandible was four times more radiosensitive compared with the maxilla. With attention to the dental and craniofacial development, occlusion and craniomandibular function, children in risk groups should be followed, and given prophylactic treatment and intervention at appropriate times to reduce the consequences of the disease itself and the therapy given.

Dentoskeletal morphology in children with Deckbiss

A comparison of dentoskeletal morphology in 176 Deckbiss malocclusions with Class I molar relationship (Class I/2) and 156 Deckbiss malocclusions with Class II molar relationship (Class II/2) was performed using lateral cephalometric radiographs. Children at the ages of 8 to 10 years and 11 to 13 years were evaluated. The results of the study revealed broad variations in the variables analysed. A relatively short lower face and an obtuse interincisal angle were the only consistent features of the Deckbiss (Class I/2 and Class II/2). Otherwise the dentoskeletal morphology of the Deckbiss was untypical. When comparing the Class I/2 and Class II/2 samples the following morphological traits were more pronounced and/or more frequent in the Class II/2 sample: 1. mandibular retrusion, 2. skeletal Class II jaw base relationship, 3. mandibular plane angle reduction, 4. jaw base hypodivergency, and 5. upper incisor retroclination. Lower incisor retroclination, on the other hand, was more pronounced and more frequent in the Class I/2 sample. Age affected exclusively the Class I/2 sample: maxillary and mandibular retrusion were seen more frequently in the younger than in the older subjects.

Postorthodontic dental changes: a longitudinal study

The conventional adolescent orthodontic patient is treated during a phase of active growth, but growth of the skeletodental complex continues after treatment and into adulthood at a much slower pace. Selection of orthodontic diagnostic and treatment regimens that produce stable and esthetic dental relationships is a continual endeavor for the orthodontic specialist. Patients should be recalled for long periods of time and the results evaluated. The present longitudinal study was completed on 36 individuals, all of whom had received comprehensive orthodontic treatment. Dental changes were assessed from cephalograms for the in-treatment period (ca. 12 to 15 years of age), posttreatment to first recall (0 = 22 years of age), and first to second recall period (0 = 30 years of age). There was considerable change in the absolute locations of the teeth, but, in reality, these changes are almost wholly attributable to growth of the bony reference structures, not dental changes per se. Growth proceeded at a very slow pace after the first recall (ca. 22 to 30 years of age ). Dental relationships, eg., FMIA, IMPA, 6L angulation, exhibited no systematic change after treatment.

Correlations between condylar characteristics and facial morphology in Class II preadolescent patients

The aim of this retrospective study was to determine correlations between condylar characteristics measured from preorthodontic tomograms of preadolescents and their facial morphologic characteristics. The sample consisted of 136 patients displaying a Class II malocclusion, a vertical or horizontal skeletal growth tendency, and ranging in age between 10 years 0 months and 12 years 6 months for males and 9 years 0 months and 11 years 6 months for females. Two groups were established: the vertical group had 68 patients, 36 males and 32 females, (average pretreatment age, 11 years 0 months); the horizontal group also had 68 patients, 29 males and 39 females, their average pretreatment age was 10 years 9 months. The central cut of axially corrected lateral tomograms of the left and right temporomandibular joints for each group was randomized, blinded, and traced for condyle/fossa measurements including: anterior, superior and posterior joint space; condylar head and posterior condylar ramus inclination; condylar neck width; and condylar shape and condylar surface area. A logistic discriminant analysis with significance values set at p < 0.05 was used to determine the most reliable condylar characteristics to predict facial morphology. A cluster analysis was completed on the significant variables to form three clusters. Numeric ranges separating these clusters were then calculated. Chi-square tests measures of association were computed for significant variables and tested for associations between facial morphologic characteristics. Condylar head inclination and superior joint space proved to be significantly correlated to facial morphology (p values ranged from 0.010 to 0.018). Patients with vertical facial morphologic characteristics displayed decreased superior joint spaces and posteriorly angled condyles. Increased superior joint spaces and anteriorly angled condyles were significantly correlated to patients with a horizontal facial morphology. No significant correlations between the other condylar characteristics and facial morphology were determined.

Opening rotations of the mandible during and after treatment

In this retrospective cephalometric study of mandibular rotational change, we studied 60 cases. All patients were treated with full fixed appliances and exhibited an opening rotation of at least 1.5 degrees during treatment, as measured on the basis of the angle of the Y-axis to the sella-nasion line (SN). Our objective was to determine whether this opening rotation was sustained during retention. Paired t tests were used to test the hypothesis that the treatment change or opening rotation was stable and that these patients did not return to their original mandible-to-cranium relationship in the posttreatment period. Stepwise regression analysis was used to determine which (if any) changes in the independent variables during treatment could predict the subsequent behavior of the angle of the mandibular plane to the SN and the angle of the Y-axis to the SN during retention. During treatment, the mean increase in the angle of the Y-axis to the SN was 2.43 degrees. After an average posttreatment period of 54 months, this angle was reduced on average by only 0.73 degrees. Stepwise linear-regression analysis indicated that none of the treatment changes seen in the independent variables strongly predicted the ensuing closing rotation seen during retention. The correlation coefficient between the Y-axis angle and the mandibular-plane angle during treatment was 0.67. Mandibular opening rotations as a consequence of orthodontic treatment do not invariably return to the pretreatment value, and their negative effects--although sometimes small--cannot be discounted. Because the preponderant evidence of a closing rotation occurs in the terminal pubertal growth stages, the net effect may be even more significant.

Nonsurgical treatment of the patient with vertical discrepancy

Conventional orthodontic treatment of the patient who has excessive anterior facial height is difficult. Many times, the patient is presented only a surgical-orthodontic option. However, some "orthodontics only" options are available. These options can generally give the patient acceptable facial balance and a good functional occlusion. The two keys are differential diagnosis and a carefully monitored force system. Conventional treatment of two patients with high angle facial dimension will illustrate these concepts.

Condylar growth and glenoid fossa displacement during childhood and adolescence

This study evaluated age and gender differences in the growth of the mandibular condyle and displacement of the glenoid fossa. The results pertain to longitudinal samples of untreated French Canadians, including 118 children and 155 adolescents. Childhood and adolescent growth were described for girls aged between 6 and 10 years and 9 and 13 years, respectively, and for boys aged between 8 and 12 years and 11 and 15 years, respectively. Four-year growth changes of the cephalometric landmarks condylion and articulare were evaluated. Mandibular and cranial/cranial base structural superimpositions were used to assess condylar growth and fossa displacement, respectively. The results showed that the condyle grew between 0.8 and 1.3 mm posteriorly and between 9.0 and 10.7 mm superiorly over the 4-year periods; the articulare landmark showed significantly more posterior and less superior growth than the condylion landmark. Relative to the cranial base reference structures, the fossa was displaced between 1.8 and 2.1 mm posteriorly and between 1.0 and 1.8 mm inferiorly. The articulare showed significantly more inferior movement than the condylion. Boys showed significantly greater superior condylar growth during adolescence than during childhood. The glenoid fossa demonstrated greater posterior and inferior displacement during adolescence than during childhood.

Mandibular incisor stability after bimaxillary orthodontic treatment with premolar extraction in the upper arch

To evaluate long-term changes in the lower incisor region, a comparison was made between children with large overjet treated with extraction of the upper first premolars and fixed appliances in both jaws and untreated children with normal occlusion. The treatment group consisted of 26 children and was studied with plaster models on 5 occasions: before treatment, at the end of active treatment, at the end of retention, after 1 year out of retention and at the last registration 4 to 5 years out of retention. The total time from the start of treatment to the last registration was 9 years and 10 months. Cephalometric registrations were made at the first and last registrations. The group of untreated children, the control group, consisted of 19 individuals. They were also studied with plaster models and lateral headfilms during a period of 10 years. The age of the treatment group and the control group at the last registration was 21.7 years and 20.4 years, respectively. At the first registration there was an available space in the lower anterior region of -0.06 mm (+/- 1.73) in the treatment group and + 0.4 mm (+/- 2.00) in the control group. At the last registration the available space for the treatment group was -1.4 mm (+/- 1.31), an extra space loss of 0.8 mm; in the control group the space loss was 1.3 mm and the available space was thus -0.9 mm. No significant difference in anterior lower jaw crowding could be seen between the treatment and control group at the last registration. Subjective ranking of the plaster models from the final registrations according to the amount of crowding in the lower anterior region showed no significant difference between the treatment and the control group.

Unbiased quantitative testing of conventional orthodontic beliefs

This study used a preexisting database to test in hypothesis from the appropriateness of some common orthodontic beliefs concerning upper first molar displacement and changes in facial morphology associated with conventional full bonded/banded treatment in growing subjects. In an initial pass, the author used data from a stratified random sample of 48 subjects drawn retrospectively from the practice of a single, experienced orthodontist. This sample consisted of 4 subgroups of 12 subjects each: Class I nonextraction, Class I extraction, Class II nonextraction, and Class II extraction. The findings indicate that, relative to the facial profile, chin point did not, on average, displace anteriorly during treatment, either overall or in any subgroup. Relative to the facial profile, Point A became significantly less prominent during treatment, both overall and in each subgroup. The best estimate of the mean displacement of the upper molar cusp relative to superimposition on Anterior Cranial Base was in the mesial direction in each of the four subgroups. In only one extraction subject out of 24 did the cusp appear to be displaced distally. Mesial molar cusp displacement was significantly greater in the Class II extraction subgroup than in the Class II nonextraction subgroup. Relative to superimposition on anatomical "best fit" of maxillary structures, the findings for molar cusp displacement were similar, but even more dramatic. Mean mesial migration was highly significant in both the Class II nonextraction and Class II extraction subgroups. In no subject in the entire sample was distal displacement noted relative to this superimposition. Mean increase in anterior Total Face Height was significantly greater in the Class II extraction subgroup than in the Class II nonextraction subgroup. (This finding was contrary to the author's original expectation.) The generalizability of the findings from the initial pass to other treated growing subjects was then assessed by retesting modified hypotheses against a second database stored sample that earlier had been drawn randomly from two other orthodontic practices. The implications of the author's study strategy to the design of future shared digital databases is discussed briefly.

The validity of two methods of mandibular superimposition: a comparison with tantalum implants

The aim of this investigation was to examine and compare the validity of Björk's and Ricketts' methods for the superimposition of serial cephalometric radiographs of the mandible for the analysis of changes over the duration of routine orthodontic treatment in growing subjects (approximately 2 years). Pre- and posttreatment lateral cephalometric radiographs of 23 children, with tantalum markers implanted in the mandible, were studied. The differences in position of six dental and skeletal landmarks between superimposition on Björk's structures and on Ricketts' corpus axis were compared with those on the basis of the implants. A rotational effect was found for corpus axis resulting from differential movement of Xi point with growth, whereas Björk's method yielded results essentially similar to those of the implant-based superimposition. This resulted in statistically significant median differences between the two methods for all landmarks except pogonion and menton. The magnitude of the differences increased with distance from the central core of the mandible and were generally greater horizontally than vertically. Although most differences were less than 2 mm, approximately 10% of the subjects showed differences greater than 4 mm for molar and incisor landmarks. These findings suggest that, for growing subjects, Björk's method should be preferred Ricketts', which cannot be relied on to indicate the true (intramandibular) changes during orthodontic treatment in growing subjects.

The nature of arch width difference and palatal depth of the anterior open bite

Measurements were made of study casts of patients with anterior open bite to compare the width of maxillary and mandibular arches and the depth of the palate. This study was designed to (1) explore the nature of the arch width difference for patients with anterior open bite, whether dental or skeletal in nature, and (2) clarify the general impression of "high" palatal vaults for anterior open bite cases, to make sure if there are "absolutely high" or "relatively high" palatal vaults. Measurements in male and female patients with open bite malocclusions were analyzed and compared with those in male and female patients with normal occlusions. Similar trends were found for both sexes. Skeletally narrowed maxillary posterior width and dentally widened mandibular posterior widths were found. Palatal depth was in the normal range in the patients with anterior open bite. Orthopedic widening of the maxillae and inclining of the mandibular posterior teeth lingually are recommended when orthodontic treatment is to be rendered to patients with anterior open bite.

Functional appliance therapy with the Bionator

Since the early 20th century, functional appliance therapy has been a significant part of orthodontic treatment, especially in Europe, where functional appliances have been used to treat many malocclusions, including some skeletal discrepancies. Although the success of functional appliance therapy as reported in numerous short-term studies from 1930 to 1975 led to an euphoric acceptance of this method, the few long-term studies, especially those comparing treated with untreated homogeneous control groups, indicated that the specific skeletal and dentoalveolar effects depended on the individual growth period and pattern of the patient. In this article, a specific functional appliance, the Bionator, is presented. Long-term follow-up studies provide indications for its use. At the present time, functional orthopedic appliance therapy has a more limited but well-defined place in our therapeutic approach. The type and character of the malocclusion determines the indications and contraindications of the functional appliance. Scientific and clinical experience has shown the importance of a differential diagnosis for each patient, which integrates etiology and morphogenesis in the individual treatment objectives for special skeletal, dentoalveolar, and functional regions. Individualization in the construction of the appliance, taking the above-mentioned factors into consideration, is essential for optimal clinical results.

Cephalometric effects of face mask/expansion therapy in Class III children: a comparison of three age groups

The purpose of this investigation was to determine the skeletal, dental, and soft tissue effects of face mask/expansion therapy and to examine the effect of age on treatment response. Pretreatment and posttreatment cephalometric radiographs from 63 subjects (4 to 13 years) who had a Class III malocclusion were analyzed. Serial cephalometric tracings of 32 subjects with Class I occlusion made at 4, 6, 8, 10, 12, and 14 years were used as controls. Landmarks were digitized on each tracing and treatment effects were measured by using cranial base and maxillary superimposition techniques. Annual rate differences were compared with t tests for the combined treated group (N = 63) and between stratified treated groups (4 to 7 years N = 15, 7 to 10 years N = 32, 10 to 14 years N = 16). The treated group (N = 63) demonstrated significant (p < 0.001) hard and soft tissue changes that resulted from treatment. Skeletal change was primarily a result of anterior and vertical movement of the maxillae. Mandibular position was directed in a downward and backward vector. Orthodontic changes contributed to the correction, and soft tissue effects resulted in a more convex profile. Minimal significant differences were observed between age groups when comparing angular and linear measurements alone. However, when analyzing the algebraic sum of treatment effects (Johnston analysis), significantly (p < 0.01) greater differences were observed in apical base change (ABCH) and total molar correction (6/6) in the younger age groups. This study demonstrates that face mask/expansion therapy produces dentofacial changes that combine to improve the Class III malocclusion. Although early treatment may be most effective, face mask therapy can provide a viable option for older children as well.

Benefit of early Class II treatment: progress report of a two-phase randomized clinical trial

Preadolescent children with overjet greater than 7 mm were randomly assigned to observation only, headgear (combination), or functional appliance (modified bionator) and were monitored for 15 months. Of the 166 patients who completed this first phase of the trial, 147 continued to a second phase of treatment. The data from the first 107 patients to complete phase 2 are available and form the basis of this progress report. During phase 1, on average there was no change in the jaw relationship of untreated children, but 5% showed considerable improvement and 15% demonstrated worsening. Both early-treatment groups had a significant average reduction in ANB angle, more by change in maxillary dimensions in the headgear group and mandibular growth in the functional appliance group. There were wide variations in response, however, with only 75% of the treated children showing favorable skeletal response. Failure to respond favorably could not be explained by lack of cooperation alone. The preliminary results from phase 2 show that, on average, time in fixed appliances was shorter for children who underwent early treatment, but the total treatment time was considerably longer if the early phase of treatment was included. Only small differences were noted in anteroposterior jaw position between the groups at the completion of treatment, and the changes in dental occlusion, judged on the basis of Peer Assessment Rating scores, were similar between groups. Neither the severity of the initial problem nor the duration of treatment was correlated with the occlusal result. The number of patients who required extraction of permanent teeth was greater in the early functional appliance group than in the headgear or control group. The option of orthognathic surgery was presented more often in the cases of children who did not undergo early treatment, but surgery was accepted or was still being considered almost as frequently in the previous headgear group as in the controls, less often in the patients previously treated with functional appliances.

The effects, limitations, and long-term dentofacial adaptations to treatment with the Herbst appliance

The purpose of this article is to summarize the existing scientific data with respect to the short- and long-term effects of the Herbst appliance on the occlusion and on the maxillo/mandibular complex. The article also discusses the treatment indications and possible treatment limitations. The Herbst method is most effective in the treatment of Class II malocclusions. Long-term stability seems to be dependent on a stable cuspal interdigitation. Marked mandibular morphological changes occur during therapy and sagittal condylar growth is increased. Posttreatment, most of the mandibular morphological changes revert and no long-term influence of Herbst treatment on mandibular growth can be verified. The appliance effect on the maxillary complex can be compared with that of a high-pull headgear. Without proper retention, however, this effect is of a temporary nature. Herbst treatment is especially indicated in the permanent dentition at or just after the pubertal peak of growth. Mixed dentition treatment is not recommended, as a stable cuspal interdigitation after therapy is difficult to achieve and relapses are prone to occur. In the nongrowing patient, the appliance should be used with great caution.

Lower arch perimeter preservation using the lingual arch

The purpose of this investigation was to determine whether the placement of a mandibular lingual arch maintained arch perimeter in the transition from the mixed to the permanent dentition, and if so, whether it was effective at preventing mesial migration of first permanent molars, or whether this migration still occurred en masse, by increased lower incisor proclination. Thirty patients were randomly assigned to either a treatment group (N = 14, mean age = 11.5 years) or a control group (N = 16, mean age = 11.3 years). Study models, cephalograms, and tomograms of the patients, taken at the beginning and at the end of the study period, were examined. Statistically significant differences between groups were found for positional changes of mandibular first molars and incisors, and changes in arch dimensions. The results indicate that the lingual arch can help reduce arch perimeter loss, but at the expense of slight mandibular incisor proclination.

The medial axis branch point in the human mandible

The medial axis method was applied to radio-cephalometric images of the mandible in 20 adults and 18 children and to panoramic X-ray images of these children, and also directly to 50 halves of dry mandibles. It was found that the location of the posterior branch point coincided almost invariably with the mandibular foramen/lingula. The foramen may be regarded as the posterior limit of the mandibular body, from which the condylar and coronoid processes branch off. The medial axis appears to reflect the developmental and functional anatomy of the human mandible.

Glenoid fossa position in different facial types: a cephalometric study

The purpose of the present study was to analyse the position of the glenoid fossa in subjects with different sagittal and vertical skeletal features. A cephalometric study was carried out on a sample of 180 subjects (90 males and 90 females, aged 7-12 years) who were combined to form three groups (60 subjects each) according to skeletal sagittal relationships and three groups (60 subjects each) according to skeletal vertical relationships. Cephalometric analysis comprised both sagittal and vertical measurements for the assessment of the position of the glenoid fossa in relation to surrounding skeletal structures. As for sagittal measurements, TMJ position was more posterior in skeletal Class II when compared with skeletal Class III. In the vertical plane, the position of the glenoid fossa relative to basicranial structures was more caudal in low angle subjects when compared with subjects with normal or high angle vertical relationships. Both basicranial structures and the posterior nasal spine may be used as reference structures for the assessment of vertical position of the glenoid fossa in diagnosis and treatment planning.

Late lower arch crowding in relation to skeletal and dental morphology and growth changes

Skeletal and dental morphology, and related growth changes during a 3-year period following second permanent molar eruption, were compared in a group of 21 subjects who had no increase in lower arch crowding, with another group of 21 subjects whose lower arch crowding had increased by 1.0 mm or more during the same period. The crowding group showed a significantly greater increase in M3 space, forward movement of the second permanent molar and increase in the inter-incisal angle than the non-crowding group. None of the other parameters examined differed significantly.

Associations between changes in selected facial dimensions and the outcome of orthodontic treatment

The purpose of this study was to determine, in children with Class II, Division I malocclusion who were treated with functional appliances, the strength of the associations between the changes over 18 months in selected facial dimensions and the success of orthodontic treatment as determined by the weighted Peer Assessment Rating (PAR). Forty-two children, between 10 and 13 years of age (mean age 11.6 years), were randomly assigned to either an untreated group (control) or a group treated with either a Fränkel function regulator or Harvold activator (treatment). The outcome of treatment was assessed on study models and the craniofacial changes were measured on lateral cephalometric radiographs. Correlation coefficients were then calculated between the differences in the cephalometric variables over 18 months and the differences in the PAR scores. In the treatment group, the effects of normal growth were held constant by partial correlation. The partial used was the change in both stature and weight. Significant positive partial correlations were found between the increases in total anterior face height, posterior face height, S-Pg, and treatment success. Significant negative partial correlations were found between downward movement of the maxilla and mandibular body and lower anterior face height and treatment success. It is postulated that these associations occurred mainly in response to the bite opening by the appliances. Treatment success was also significantly associated with maxillary restriction, an increase in the SNB angle and a reduction in the ANB angle. Changes in B point due to proclination of the mandibular incisors were considered to be responsible for the two latter significant associations. Although mandibular length increased significantly in the treatment group, as compared with the control group, it was not significantly associated with treatment success.

Maxillary and cranial base changes during treatment with functional appliances

The purpose of this prospective study was to investigate the maxillary and the cranial base changes after treatment with the Harvold activator and the Fränkel function regulator appliances. Forty-two children, who are 10 to 13 years old, with Class II, Division 1 malocclusions were matched in triads according to age and sex and randomly assigned to either the control, Harvold activator, or Fränkel function regulator group. Lateral cephalometric radiographs were taken at the start of the study and 18 months later. Both appliances reduced the overjet by tipping the maxillary incisors palatally and, as a consequence, the length of the maxillary arch was reduced. The appliances had no effect on either the horizontal or vertical position of the maxillary molars. Small, but statistically significant, changes in the cranial base angle in the Fränkel function regulator group were attributed to relatively large changes at basion in several children, influencing the results because of the small size of the sample. The appliances had no effect on the position of the maxilla.

Orthodontic management of the short face patient

A short lower face may accompany various types of malocclusions depending on the structural etiology. Because most cephalometric analyses focus on the anteroposterior plane of space, they are often insufficient in diagnosing a significant vertical dysplasia. This article describes a cephalometric analysis that examines not only the vertical proportions of the face, but the various anatomical features that contribute to the dysplasia. Diagnosis is further enhanced by evaluating the facial profile with the mandible postured at various amounts of opening, suggesting the degree of vertical discrepancy. Traditional orthodontic therapy corrects the associated malocclusion but is usually ineffective in changing inherent facial proportions. However, several orthopedic methods have shown the ability to increase lower facial height when used in combination with nonextraction orthodontic mechanotherapy. Adults with short faces require a combination of orthodontics and orthognathic surgery. The Class II malocclusion can usually be managed by surgically advancing the mandible with the curve of Spee maintained. In cases of vertical maxillary deficiency, the LeFort I osteotomy with inferior repositioning provides the spatial correction that is needed. Two cases are presented to illustrate the cephalometric and facial analyses used in diagnosis, as well as the common surgical procedures to manage the short face patient.

A pressure-distribution sensor (PDS) for evaluation of lip functions

The purpose of this study was to develop and to test a pressure-distribution sensor (PDS) for evaluating lip functions. The PDS is fabricated as a disposable cartridge and is based on the principle of optical-pressure conversion used in tactile sensors of robot arms. Its advantages are in measuring sealing forces, contact area, and pressure-distribution patterns of the lips at maximum effort. We used the PDS to evaluate pressure-distribution patterns of long-face subjects with extremely large interlabial distances. The results suggest that the PDS is a useful device for evaluating lip sealing functions and their changes after orthodontic therapy or orthognathic surgery.

Mandibular skeletal changes induced by early functional treatment of Class III malocclusion: a superimposition study

A superimposition study on mandibular stable structures was performed to evaluate changes in mandibular rotation and in the direction of condylar growth induced by early treatment of Class III malocclusion by a functional appliance (removable mandibular retractor). A sample of 18 children with treated Class III malocclusions, mean age at the first observation (immediately before the beginning of treatment) 5.47 +/- 1.14 years, mean age at the second observation 8 +/- 1.29 years, mean observation period 2.5 +/- 0.9 years, was compared with a control group of 18 children with untreated Class III malocclusions, mean age at the first observation 5.72 +/- 1.11 years, mean age at the second observation 7.86 +/- 1.44 years, mean observation period 2.27 +/- 0.92 years. No statistically significant difference between the two groups was recorded for positional (total) rotation of the mandible. A significant upward-forward direction of condylar growth was assessed in the treated group (p < 0.001). This therapeutically induced change in growth direction of the mandibular condyle was considered a skeletal sign of anterior morphogenetic rotation of the mandible, i.e., a mechanism compensating for excessive mandibular growth.

Chernoff faces: an orthodontic application

This retrospective study examined 21 children (12 males and nine females) with Class III malocclusions, who had been successfully treated by a non-extraction technique and for whom follow-up records were available at least 2 years after all treatment and retention had ceased. On the basis of their post-retention records, children were divided into two groups: those who remained stable (n = 10) and those whose treatment relapsed (n = 11). A graphical technique of data description, Chernoff faces, in which variables for each individual may be portrayed by appropriate scaling of selected facial features, was used to construct cartoon faces for each child. Seven variables, overjet, overbite, upper and lower incisor inclination, the numbers of anterior and posterior teeth in lingual occlusion and the angle ANB were chosen and diagrammatic faces drawn using data from both the start of treatment and post-retention stages. These were arranged according to relapse status and scrutinized to determine whether the groups possessed any common features which were related to the outcome of treatment. The faces showed a wide range of variation, especially at the pretreatment stage. Whilst the cartoons were easy to read, no typical features could be identified at the start of treatment which might indicate that therapy would later relapse.

Changes in craniofacial development induced by growth hormone therapy in children treated with bone marrow transplantation

The effect of growth hormone (GH) treatment on craniofacial development was studied in nine children exhibiting low growth velocity after bone marrow transplantation (BMT). Comparisons were made with seven BMT children who had not received GH. Two groups of age- and sex-matched healthy children served as controls for the respective patient groups. After an average observation period of 3.5 years, the BMT children not treated with GH exhibited significantly reduced mandibular length and alveolar height (p < 0.01). The increase in mandibular length was only 30% of that found in healthy controls. Maxillary growth was less affected by BMT treatment. In the GH treated group, no significant differences were found in craniofacial growth increments compared with controls. Although exogenous GH therapy in this group of children did not induce a catch-up growth, it appears to have prevented further loss in growth potential.

Control of the vertical dimension in Class II correction using a cervical headgear and lower utility arch in growing patients. Part I

A retrospective cephalometric study was performed comparing three groups of 30 growing patients with Class II, Division 1 malocclusions. Group 1 was treated with a cervical headgear/lower utility arch combination (CHG/LUA), group 2 was treated with a cervical headgear alone (CHG), and the third group was untreated. The average treatment time was 1 year, 6 months. No other appliances were used during this period. Maxillary and mandibular dental and skeletal treatment responses were compared with an analysis of variance (ANOVA) and a Scheffe's test. In addition, a multiple stepwise regression was performed to determine whether pretreatment measures of facial pattern were accurate predictors of mandibular rotational response. Both treatment groups demonstrated significant reduction in maxillary protrusion. The CHG-only group showed significantly greater anterior descent of the palatal plane as compared with the untreated group. The maxillary molars showed significant distal movement in both treatment groups without any extrusion beyond that seen with normal growth. The maxillary incisor demonstrated significant retroclination in the CHG-only group. There was no statistical difference among the groups for variables commonly used for measuring mandibular rotation or protrusion. The change in vertical position of the lower molar was not significantly different among the groups. A CHG as used in this study produced maxillary orthopedic and orthodontic changes without upper molar extrusion beyond that seen with normal eruption and in the absence of an opening rotation of the mandible, even in subjects with dolicocephalic facial patterns. The LUA did not appear to influence lower molar eruption or mandibular rotational response. None of the commonly used predictors of facial pattern, such as the Y-axis, XY-axis, or MP angle, accurately predicted mandibular rotational response. Further study would be necessary to ascertain whether this was a result of their invalidation as predictors, or a result of the treatment strategy employed.

Maxillary molar vertical control with the use of transpalatal arches

Upper molar eruption and its clinical significance to vertical control were measured in a retrospective cephalometric study of 40 patients (20 with and 20 without transpalatal arches) treated in a private practice. Pretreatment and posttreatment cephalometric values were compared to determine how well the patients were matched. No statistically significant differences were noted between control and test groups for the following variables: maxillary and mandibular molar vertical eruption per year, maxillary complex vertical growth per year, effective horizontal condylar growth per year, ratio of effective horizontal pogonion movement to effective vertical pogonion movement, ratio of effective vertical condylar growth to the summation of maxillary, and mandibular vertical molar eruption plus maxillary complex vertical growth, beginning age, and ending age. The control group exhibited statistically greater forward positioning of pogonion and greater effective vertical condylar growth than did the treatment group.

Effects of mandibular growth patterns on the development and configuration of the face in patients with unilateral cleft lip and palate

Radiographic cephalometry has been used for the assessment of the effects of mandibular rotation and of posterior growth displacement of the temporomandibular joint on the development of the face and on overjet in 43 patients with complete unilateral cleft lip and palate between the ages of 10 and 15 years. Rotation acted mainly on vertical facial measurements and on the position of the lower jaw. The degree of posterior displacement of the temporomandibular joint exerted an influence on the position of the mandible, on the difference between the functional length of the upper and lower jaw, and on the occlusion of incisors. The direction of growth of the mandible as a whole represented the result of a combination of changes produced by the rotation of the jaw and by the degree of posterior displacement of the temporomandibular joint. The most favourable conditions for development were a combination of the neutral type of rotation with a more pronounced posterior displacement of the temporomandibular joint.

Assessment of symphysis morphology as a predictor of the direction of mandibular growth

The purpose of this study was to determine whether symphysis morphology could be used as a predictor of the direction of mandibular growth and to assess growth changes of the symphysis. Cross-sectional data included lateral cephalometric radiographs of 115 adults (58 women, 57 men) with the longitudinal sample a subset of 62 subjects (30 females, 32 males) at four age groups. The direction of mandibular growth was evaluated with seven cephalometric measurements that included Y-axis, SN to mandibular plane, palatal plane to mandibular plane, gonial angle, sum of saddle, articulare and gonial angles, percentage lower facial height, and posterior/anterior face height. The mandibular symphyseal dimensions studied were height, depth, ratio (height/depth), and angle. Symphysis morphology was found to be associated with the direction of mandibular growth, especially in male subjects with symphysis ratio having the strongest relationship. A mandible with an anterior growth direction was associated with a small height, large depth, small ratio, and large angle of the symphysis. Conversely, a posterior growth direction was associated with a large height, small depth, large ratio, and small angle of the symphysis. Symphysis dimensions continued to change until adulthood with male subjects having a greater and later occurring change compared with female subjects.

The etiology of late lower arch crowding alternative to mesially directed forces: a review

The causes of late crowding in the lower arch alternative to mesially directed forces are reviewed under the headings: late mandibular growth, skeletal structure and complex growth pattern, soft tissue maturation, periodontal forces, tooth structure, occlusal factors, and connective tissue changes. A multifactorial basis for late lower arch crowding seems likely.

An evaluation of the condylar position of the temporomandibular joint by computerized tomography in Class III malocclusions: a preliminary study

The position of the condyle within the glenoid fossa was investigated in 21 adult patients with untreated skeletal Class III relationships and 18 adult patients with normal occlusions as controls. Axial computerized tomography (CT) was used for precise measurements of the bony structures of the temporamandibular joints. In horizontal sections, the mediolateral dimensions of the condyles of the patient group were found to be statistically higher in the fossa. The anteroposterior glenoid fossa dimensions were found to be smaller in Class III malocclusions. The smaller anterior joint space dimensions in the Class III relationships were also found to be statistically significant. The analysis of the measurements suggests that relative condylar protrusion with a relative mediolateral elongation of the condyle within a relatively smaller glenoid fossa are correlated with the anterior mandibular displacement in skeletal Class III malocclusions.

Clinical ramifications of posterior and anterior facial height changes between treated and untreated Class II samples

Some clinicians have suggested that one primary difference between successful and unsuccessful Class II treatment outcomes is the relative change of anterior and posterior facial heights. Successfully treated cases are claimed to exhibit greater increases in posterior facial height (PFH, articulare to gonion) than in the anterior facial height (AFH, menton to palatal plane). This conjecture was tested here by recalling a treated Class I sample and a treated Class II sample and by comparing the differences found in these samples to an untreated Class II sample at the same ages. The PFH/AFH ratio increased significantly more in the treated Class I and Class II samples during the active phase of treatment than in the untreated Class II sample at the same ages. During the years from posttreatment to recall (mean = 6 yrs), there was a significant increase in the PFH/AFH ratio in the treated Class II sample due to a greater increase in PFH than AFH. This ratio continued to improve after all appliance therapy had been discontinued, and it did not occur in the treated Class I sample nor in the untreated Class II sample. The conclusion was that the patient with a Class II malocclusion, if treated, continues to change favorably over time. This favorable change, in turn, helps maintain the Class II correction.

Predictors of relapse in orthodontically-treated Class III malocclusions

This study aimed to investigate the possibility of predicting relapse from the pretreatment records of children with orthodontically treatable Class III malocclusions. Sixty-four patients were studied: 31 individuals had been treated by a non-extraction technique, the remaining 33 with mid-arch extractions. Cephalometric and model data taken at the start of treatment and at least 2 years after all treatment and retention had ceased were examined. An individual diagnosis of relapse or stability was made from the post-retention records and the start of treatment records analysed in relation to this information. The capacity for predicting the observed outcome of therapy was assessed in three ways: correlation coefficients, the number of cephalometric measurements exceeding two standard deviations from a control group mean, and discriminant analysis. Only the latter proved an effective indicator of relapse, with a separate discriminant model being necessary for each sub-group.

Systematic and random errors associated with Johnston's cephalometric analysis

This study examined intra- and interexaminer systematic and random errors associated with Johnston's cephalometric method of assessing skeletal and dental changes from pairs of radiographs. Data were obtained from the tracings of radiographs of 30 mixed dentition subjects, who had been treated to correct a Class II malocclusion. Measurements included molar and incisor crown movements relative to basal bone, apical base change, maxillary and mandibular displacement relative to the cranial base, and total molar and overjet reduction. In addition, the change in axial inclination of the incisors and molars was determined. A paired t-test for each pair of replicates for each measure was performed to examine inter- and intra-examiner bias. Estimates of the random error, the coefficient of reliability, and confidence limits (95 per cent level) of a single determination were undertaken. No systematic errors occurred between/within examiners for any linear or angular measure. Interexaminer random errors, based on the standard deviation of the mean difference between replicates, were greater than intra-examiner random errors for 12 out of 13 parameters. Measures assessing molar correction and overjet reduction had the least amount of random error variance within and across judges, while changes in mandibular position had the greatest. Because considerable random errors occurred, the Johnston analysis when used to assess skeletal changes, as well as individual molar and incisor movements, may have limited utility in clinical practice for the individual case.

Masticatory function in a patient with mandibular midline cleft

Bone grafting of a midline cleft is required to allow reasonable masticatory function. However, changes in the rhythm of mastication have not been investigated before and after such bone grafting procedures. We performed bone grafting in a patient with multiple craniofacial anomalies including a midline mandibular cleft. The patient showed a marked improvement in the rhythm of mastication after repair of the midline mandibular defect. Bone grafting proved to be an effective method for securing stable occlusion with better mandibular movement.

[Dentoalveolar adaptation in vertical jaw-base discrepancies]

The aim of this study was to determine the constancy and the extent of the dentoalveolar adaptation in subjects with disharmonious vertical jaw base relationships. Lateral head films in centric occlusion of 66 untreated adults were analysed. The subjects were divided in three facial type groups on the basis of the mandibular base angle (ML/NSL): hypodivergent (n = 23), normodivergent (n = 18), and hyperdivergent (n = 25). The relationships between maxillary and mandibular anterior and posterior dentoalveolar heights and vertical jaw base relationship were ascertained. The study revealed the following: an increase in vertical jaw base angle resulted in 1. an increase in maxillary and mandibular anterior and posterior dentoalveolar heights, 2. a larger increase in maxillary than in mandibular dentoalveolar height, and, 3. a larger increase in anterior than posterior dentoalveolar height. The study divulged the presence of dentoalveolar adaptation in subjects with a divergent vertical jaw base relationship. This adaptation, however, was inconsistent and in some cases incomplete.

A study of reference lines for mandibular plane angles

Four mandibular plane angles, MP-sella nasion, MP-Frankfort horizontal, MP-articulare nasion, and MP-gnathion occiput, were compared. Highly significant correlations were found among all four. The relation of an extension of the mandibular plane to the posterior inferior outline of the cranium was found to provide a valid indication of mandibular plane angle. Articulare nasion was found to be the reference line most likely to provide a true indication of the mandibular inclination rather than a reflection of a variation in the reference line itself.

Treatment of Class II high angle malocclusions with the Herbst appliance: a cephalometric investigation

The purpose of this study was to examine the results of treatment of Class II malocclusions by using two different designs of the Herbst appliance. Cephalometric records from lateral headplates of 19 consecutively treated Class II cases were evaluated. The headplates were taken before and after the treatment stage in which the Herbst appliance was used. The patients were divided into two groups: the first group, normohypodivergent, was treated with the Herbst appliance attached to bands; the second group, hyperdivergent, was treated with the Herbst appliance attached to acrylic splints in which a high-pull headgear was also used. The results were compared between these groups and with a control group age-matched from Bolton standards to match the changes in the Herbst samples against what might be expected in case of normal growth during similar periods of time. The results of the investigation revealed the following: (1) 9 months of treatment resulted in Class I dental arch relationships in all 19 cases; (2) the Herbst appliance attached to bands did not significantly modify the vertical growth pattern of the normohypodivergent patients; and (3) in hyperdivergent patients, the use of a Herbst appliance attached to acrylic splints in conjunction with the use of a high-pull headgear allowed a better control of the vertical dimension, as assessed by the cephalometric parameters (FA, FMA, Go-Gn-SN). The clinician should be aware of the different dentofacial changes induced in the vertical plane by different designs of the Herbst appliance to better program treatment strategy.

Mandibular growth estimated by four cephalometric measurements

Mandibular growth was estimated by four cephalometric measurements on three lateral cephalograms of 21 subjects. The estimates made by three standard cephalometric approaches were compared with that made by a "scientific" method. The scientific method was based on the change in position of the cephalometric landmark condylion on cephalograms orientated on two metal implants inserted in the mandible. The other three investigated "standard" cephalometric methods were each based on estimating the difference in length between two cephalometric landmarks: (1) pogonion-condylion, (2) pogonion-articulare, and (3) maximum mandibular length. In general, the individual estimates of the amount of mandibular growth by the scientific method and that estimated by each of the standard cephalometric methods were not proportional. Some factors affected the estimates of mandibular growth. For example, (1) the growth direction of the condyle, (2) the change in position of pogonion on the mandible during the growth, and (3) the apposition of bone on the chin in some cases. The amount of mandibular growth, which is estimated by the standard cephalometric methods, and growth velocity curves, which is based on such estimates, are therefore not valid. Accordingly, conventional cephalometric analyses are not as reliable at traditionally envisaged.

A long-term comparison of nonextraction and premolar extraction edgewise therapy in "borderline" Class II patients

The long-term effects of extraction and nonextraction edgewise treatments were compared in 63 patients with Class II, Division 1 malocclusions who were identified by discriminant analysis as being equally susceptible to the two strategies. A lateral cephalogram, study models, and a self-evaluation of the esthetic impact of treatment were obtained from each of the 33 extraction and 30 nonextraction subjects. The average posttreatment interval was 14.5 years. Although the two strategies produced significant, long-lived differences in the convexity of the profile and the protrusion of the dentition (the nonextraction patients were about 2 mm "fuller"), half of the nonextraction patients and three fourths of the extraction patients ultimately presented with less than 3.5 mm of lower incisor irregularity. The two groups showed an essentially identical pattern of posttreatment relapse/settling that was related more to the differential growth of the jaws than to the posttreatment position and orientation of the denture. Because in the end the various tooth movements tended to cancel one another, excess mandibular growth was also the most important net contributor to the molar and overjet corrections. In the process, both groups showed a marked forward displacement of the mandible, both at the chin and at the condyle. Finally, although it is probable that most of the present sample would today be treated by expansion, the 30 patients who actually received this presumably correct treatment rated their appearance no more highly than did the extraction subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Mandibular growth direction with conventional Class II nonextraction treatment

The purposes of this study were (1) to compare the direction of mandibular growth (MGD) during treatment and retention for a group of treated Class II patients with untreated controls, and (2) to investigate the relationship between the MGD during treatment and the pretreatment skeletal structure. Pretreatment, posttreatment, and 2 years posttreatment lateral cephalograms of 26 Class II, Division 1 subjects who were treated "nonextraction" with low- or straight-pull headgears were compared with an untreated control group of 15 subjects. Mandibular growth direction was interpreted as the movement of the point gnathion relative to the S-N line when successive tracings were superimposed on the S-N line at S. On average, MGD appeared more vertical during treatment. Posttreatment MGD was generally more horizontal than that during treatment but was also extremely variable. Three of the pretreatment skeletal measures studied, especially the articular angle (SArGo), were significantly related to MGD during treatment. The inclination of the mandibular ramus is apparently an important indicator of how mandibular growth will respond to Class II treatment mechanics.

A comparison of jaw muscle cross-sections of long-face and normal adults

Long-face subjects have smaller maximum molar bite forces than do normal individuals. This has been attributed both to differences in moment arms and size of the jaw muscles. In this study, a comparison was made between the mid-belly cross-sectional areas of the jaw muscles of 13 long-face and 35 normal adults by means of serial MRI scans. The subjects were selected on the basis of anterior lower face height as a percentage of anterior total face height. These and other cephalometric variables were measured from lateral radiographs. In the long-face group, the cross-sectional areas of the masseter, medial pterygoid, and anterior temporal muscles were, respectively, 30%, 22%, and 15% smaller than in the control group. By a discriminant analysis and a multivariate analysis of variance, these differences were found to be significant (p less than 0.001). The findings of this study hint that differences in the sizes of the jaw muscles of long-face and normal subjects might explain, in part, the observed differences in maximum molar bite force.

Cervical and craniocervical posture as predictors of craniofacial growth

The present study aimed to determine whether growth changes in craniofacial structure could be predicted by variables expressing the postural relations of the head and the cervical column. The sample comprised 34 children, 16 girls and 18 boys. Cephalometric radiographs obtained in natural head position (mirror position) were taken on two occasions before orthodontic treatment. Mean age was 9.9 years at time 1 and 12.7 years at time 2. Selection of the sample was based on skeletal maturity at time 2 indicating peak activity in pubertal growth. Forty-one reference points and four fiducial points were digitized on each film. Individual growth changes in craniofacial structure were determined by computerized structural superimposition of the digitized sets of points. Correlation coefficients were calculated between 11 postural variables at the first observation and the subsequent growth rate in 36 structural variables. Uniform fields of low to moderate correlation coefficients significant at the 5%, 1%, and 0.1% levels (0.3 to 0.6) were found for eight structural variables, indicating that a small craniocervical angle and a backward-inclined upper cervical column at time 1 was associated with horizontal facial development characterized by reduced backward displacement of the temporomandibular joint (TMJ), large maxillary growth in length, increased facial prognathism, and larger than average true forward rotation of the mandible; whereas, a large craniocervical angle and an upright position of the upper cervical column at time 1 was associated with vertical facial development characterized by large backward displacement of the TMJ, reduced growth in length of the maxilla, reduced facial prognathism, and less than average true forward rotation of the mandible. The findings are in agreement with a theoretical model for the developmental interaction between head posture and facial structure.

Cephalometrics of anterior open bite: a receiver operating characteristic (ROC) analysis

A new approach is presented for the evaluation of cephalometric measurements in which a measurement is considered to be a diagnostic test for the presence or the absence of some component of malocclusion. This approach allows cephalometric measurements to be judged by the criteria that are generally used for clinical diagnostic tests, including determination of sensitivities, specificities, positive and negative predictive values, and, most important, receiver operating characteristic (ROC) curves. In this study, ROC curves are generated for the relationship between several skeletal cephalometric measurements and anterior dental open bite in a sample of 1541 orthodontic patients. The overbite depth indicator is found to be a better diagnostic criterion for the presence of dental open bite than any other commonly used skeletal cephalometric measurement or ratio. ROC curves are of substantial value for evaluating the diagnostic information of cephalometric measurements.