Search

This study was conducted to evaluate the effects of chin cup therapy on the mandible and its dentition in persons with skeletal Class III malocclusion. The patients selected for this study were Japanese females treated with the extraoral chin cup appliance. Both the control and treatment samples were obtained from Japanese Universities where the longitudinal data were gathered. Lateral cephalometric radiographs were taken on the average of every 6 months for the treatment group and every year for the control group. Ten treated patients and seven control patients were studied. The duration of chin cup therapy was variable but averaged 3 years 1 month. The cephalograms were digitized on an electronic screen, and a cephalometric analysis was recorded from a computer program. The rate change values were then compared with those of the control group to yield a comparison of changes in mandibular growth rate, direction, and pattern in the treatment group. Active and posttreatment effects were evaluated. All measurements for the rate of change of absolute mandibular length were reduced by 60% to 68% from the control rate of growth during therapy. The mandible exhibited less downward displacement relative to cranial base during treatment. The mandibular plane angle and the gonial angle closed with growth in the Class III control sample but were variable in the treatment group. The skeletal profile was improved with treatment. This study indicates that the chin cup may be a viable mode of treatment for the preadolescent and adolescent mandibular prognathism patients.

In the construction of a visual treatment objective, prediction of the changes in lip morphology is of great importance. A major factor is the vertical position of the embrasure and its relation to the incisal edges of the upper incisors. An aid to the problem of incompetent lips is hereby suggested.

Treatment with the activator, the Fränkel appliance, and the edgewise appliance was compared in three separate groups; each group consisted of twenty-five nonextraction cases of Class II, Division 1 malocclusion. Hard- and soft-tissue profile changes caused by growth and treatment were assessed by means of pretreatment and posttreatment lateral cephalograms. Anterior movement of A point was 1.6 mm more in the activator group than in the fixed-appliance group. The most anterior point on the maxillary incisor moved 1.5 mm more distally in the fixed-appliance sample than in the functional groups. Among the three groups, the activator sample showed the most anterior movement of the mandible (2.3 mm); the fixed group showed the least (0.6 mm). The fixed-appliance group showed more posterior rotation of the mandible than the activator group. However, relative to cranial base, the movement of the mandibular symphysis was not statistically different in the three groups. There were little differences among the treatment groups with regard to changes in the soft-tissue profile. In clinical terms, there was a remarkable similarity in the changes that occurred in the three treatment groups.

Integrated data from lateral cephalometric radiographs and study models of fifty-three patients were studied to assess the interactions between dimensional changes occurring during orthodontic treatment and the postretention stability of these changes. A new technique was developed to study distal movement of canines. Distal movement of canines did not ensure a stable increase in intercanine width. There was no significant relationship between mesiodistal position of the first molars and changes in intermolar width. Eruption of the first molar in the postretention period was associated with greater stability in overbite. There was no great degree of correlation between depth of the curve of Spee and inclination of the occlusal plane or between changes in arch length and changes in inclinations of the incisors.

Many traditional cephalometric analyses used do not consistently reflect the extent of anteroposterior or vertical jaw dysplasias. Nor do such analyses give accurate information as to which jaw(s) is at fault. The proportionate template is designed as a diagnostic aid which enables the clinician to identify and determine rapidly the extent of craniofacial skeletal jaw discrepancies in adults. The template is found to be particularly useful for orthodontists and surgeons engaged in orthognathic surgery. (Proportionate templates are available upon request from the author).

1. Four arch length prediction equations (Nance, Johnston-Tanaka, Moyers, and Hixon-Oldfather) were compared by examining pretreatment casts, pretreatment intraoral radiographs, and posttreatment casts of forty-one patients of mixed-dentition age. 2. A comparison of correlation coefficients and slopes of the predicted arch length versus the actual arch lengths revealed that the Hixon-Oldfather method conformed closest to the ideal. 3. No combination of the four methods produced a more accurate equation than the single most accurate method. 4. Neither the sex of the patient nor the type of occlusion affected the prediction accuracy of any of the four equations. 5. All methods tend to overpredict the arch length size by 1 to 3 mm., with the exception of the Hixon-Oldfather equation, which underpredicted by approximately 0.5 mm. 6. An analysis of the intrainvestigator error showed a very low standard error of estimate for individual tooth measurements and for the prediction values. 7. A variance analysis showed that most of the variation was due to arch length (85%), a slight amount was due to the prediction method (8%), and 6% of the variation was due to the rater. 8. A low correlation was found between space available versus actual discrepancy and space available versus actual arch length. 9. High correlation coefficients were found for the predicted arch lengths when compared with the actual arch lengths. As expected, the correlation coefficients for the predicted widths of only the canines and premolars compared with the actual widths were not quite as high.

1. From this study, it was found that in cases treated by the Begg technique one can anticipate greater retraction of the anterior dental units in nonextraction (see article) cases, in both types of premolar extraction cases, and in cases, involving extraction of first molars plus first premolars than would be expected on the basis of root surface area resistance values. 2. There is a likely explanation for this. Molars were maintained upright and allowed to move bodily only while incisors were not only moved bodily but often partially tipped as well. 3. The actual mean anterior retraction in first molar extraction cases exhibited a close approximation to the expected mean anterior retraction values in relation to root surface resistance values. 4. Second premolar extraction is one answer to overretraction and has the added edge of creating even less incisor retraction than second premolar extraction. 5. It was also found that the extraction of premolars alone did not result (see article) in a significant change in the increased eruption of the third molars into functional occlusion. A very significant improvement in the rate of sucessful third molar eruption was found in first molar extraction cases and in cases involving extraction of first molars plus first premolars. 6. The mean ages of the patients in the various treatment categories at the start of treatment were similar enough to each other to suggest that age at the start of treatment had no bearing on the success rate of third molar erup tion. Extraction-site selection seemed to be the dominating factor in successful third molar eruption. 7. It was found that the group of cases that exhibited the least amount of anterior retraction also inhibited the least amount of anterior relapse and, conversely, the group of cases exhibiting the greatest amount of anterior retraction also exhibited the greatest amount of anterior relapse. (see article) 8. The nonextraction cases, with no extraction space to close, were treated in the shortest mean time, while the eight-tooth (first molar plus first premolar) extraction cases having the greatest amount of extraction space required the greatest amount of mean treatment time.9. In conclusion, it can be said that changing the location of the extraction site resulted in a change in relative root surface areas of the opposing anchor units in the anterior and posterior segments. There was a definite and predictable change in the amount of anterior retraction achieved by varying the location of the extraction site. This should be considered in the diagnosis, so that a desired treatment goal for the final position of the incisors within the facial profile can be achieved.

Mandibular treatment changes were related to somatic maturation in 70 consecutive cases of Class II malocclusion (52 boys and 18 girls, aged 10 to 16 years) treated with the Herbst appliance for an average period of 7 months. Sagittal and vertical alterations in mandibular condylar growth and sagittal changes in molar and incisor tooth position were analyzed by means of mouth-open profile roentgenograms. The somatic maturity level of the patients was assessed by means of longitudinal growth records of standing height. The treatment period was related to the peak height velocity by dividing the patients into three growth-period groups: prepeak, peak, and postpeak. Herbst treatment resulted in Class I dental arch relationships in all patients. Post-Herbst treatment changes were not evaluated in this study. Sagittal condylar growth was increased and the mandibular molars and incisors were moved anteriorly. When the mandibular skeletal and dental changes were related to the subjects' somatic maturation, significant differences between the different growth periods existed in boys and tendencies were noted in girls as follows: sagittal condylar growth was most pronounced in the peak period, anterior molar movement was equally large in all growth periods, and anterior incisor movement was most extensive in the postpeak period. To take advantage of the increase in condylar growth response and to reduce the time of posttreatment retention, it is suggested that Herbst therapy be instituted close to peak height velocity.

The dental casts and cephalometric records of forty-three patients exhibiting bilateral congenital absence of maxillary lateral incisors were evaluated to determine the nature and extent of any concurrent craniofacial and dental anomalies. The effects of bilateral orthodontic space closure were evaluated on a subsample of twenty-two cases. The data revealed normal dental arch length, arch width, overjet, and overbite, while significant tooth size discrepancies were found in several anterior and posterior teeth. Craniofacial deviations from normal included smaller maxillary length, smaller mandibular length, smaller anterior cranial base, and nasal bone. Vertical facial dimensions, both anterior and posterior, were significantly less, as was the mandibular plane angle. Soft-tissue examination revealed a 10 degrees greater nasiolabial angle, which was increased a further 5 degrees as a result of a mean incisor retraction of 1.5 mm during space closure. The craniofacial anomalies noted in the present sample were similar to those seen in persons with clefts and may reflect a common etiology related to a developmental disturbance during fusion of the facial processes in utero. In the treatment of patients with bilateral congenital absence of maxillary incisors, mechanotherapy designed to open the mandibular plane, increase the vertical dimension, and move the maxillary posterior teeth forward is recommended in order to prevent worsening the Class III tendency and to minimize maxillary incisor and upper lip retraction. Most cases will require significant mesiodistal reduction in tooth size in order to achieve an optimal occlusion.

Posttreatment occlusion following orthognathic surgery is often different from that predicted in the treatment plan. Differences between intended and actual occlusion may be treatment-induced occlusal errors caused by mismatches between the centers of rotation of the mandible and of the articulated models. Discrepancies in the position of the articulator center of rotation (relative to the position of the center of rotation of the patient's mandible) influence the magnitude of occlusal errors. A computer model was developed to quantify these errors. As the center of rotation of the articulated models becomes more divergent from the patient's center of rotation, the magnitude of the occlusal errors increases. This magnitude increases most rapidly along the line that is perpendicular to the line joining the patient's center of rotation and a preselected mandibular landmark (incisor tip or molar cusp, for instance). For small changes in vertical dimension, clinically insignificant errors result, independent of the degree of mismatch between the centers of rotation. Clinical implications of these findings are discussed.

A total of thirty-six Japanese adult subjects (consisting of eighteen men and eighteen women) with normal occlusion and harmonious facial features were subjected to cephalographic examination for the purpose of studying their soft tissues. Out of this group, twenty were selected and compared with twenty Class II, Division 1 and twenty Class III patients for the purpose of establishing an appropriate diagnostic guide for the Tweed triangle. These are our conclusions: 1. The Z angle of the Japanese subjects with normal occlusion was 69.70 degrees for the men and 71.75 degrees for the women. There is no significant difference between the sexes. 2. Although there are no significant differences between the sexes for the integumental and total chins, there is slight sexual difference for the upper lip measurement. 3. As compared to the subjects with normal occlusion, there is a significant difference for the Z angle of Class II, Division 1 and Class III patients. 4. In this study, the measurements of the Tweed triangle were FMA 27.28 degrees, IMPA 95.50 degrees, and FMIA 57.22 degrees. On the basis of this study and the reports of other Japanese investigators, we would like to suggest an FMIA of 57 degrees as being the most suitable basis for the diagnosis of Japanese patients, but this should be modified according to the FMA value.

Transseptal fibers are a part of the gingival group of fibers of the periodontal membrane, and they are very tough and resistant. They form a chain from tooth to tooth which, provided that it remains intact and is sufficiently strong to resist displacing muscular pressures, will preserve the contacts between the teeth throughout the arch. If the continuity of the chain is interrupted, the balance of the forces acting upon the teeth on either side of the break is upset and considerable displacements can occur. Maxillary median diastemas are classified as "simple" or "persistent" according to their etiology, and an operation to clear the upper midline suture of transeptal fibers is described as an essential part of the treatment of persistent upper median diastema.

Fractured, congenitally missing, or avulsed maxillary incisors can often jeopardize the esthetic appearance of the remaining maxillary anterior teeth after orthodontic treatment. In many cases the unesthetic appearance is related to the irregular clinical crown lengths of either the fractured teeth or those that have been substituted for the missing teeth. The results of five cases with either fractured or traumatically avulsed central incisors are reported. Selective tooth intrusion and restorative techniques were used during the finishing stages of orthodontic treatment to improve the final esthetic result. The advantages and disadvantages of the intrusion technique are discussed.

The purpose of this study was to evaluate the effect of pharyngeal flap surgery on subsequent facial growth in patients with cleft lip and/or palate. Pharyngeal flap surgery is used in such patients to partially obliterate the velopharyngeal port, reducing hypernasal speech. Thirty-four patients (18 with cleft palate only, 16 with unilateral cleft lip and palate) were selected from the longitudinal growth study of the H.K. Cooper Clinic. Seventeen of these (9 with cleft palate only, 8 with unilateral cleft lip and palate) underwent pharyngeal flap surgery between the ages of 5 and 7 years. The other seventeen patients did not undergo pharyngeal flap surgery and served as a control group for this study. Serial lateral cephalometric radiographs were traced and digitized (ages 3 to 5, preflap; ages 7-10, postflap). Fourteen skeletodental measurements (six angular, six linear, two derived) were taken to determine whether pharyngeal flap surgery may be related to subsequent facial growth changes. The data from the 17 flap patients were compared with control data taken from the other seventeen patients. The groups were matched for sex, cleft type, and similarity of presurgical mandibular growth direction (facial axis angle). Results obtained demonstrate several significant areas of change following flap surgery, including a decrease in facial axis angle, an increase in Frankfort-mandibular plane angle, an increase in incremental gains in lower anterior face height, and increased retroclination of upper and lower incisors in the flap group as compared to their matched controls.

The integration of the diagnostic and treatment skills of both the orthodontist and the maxillofacial surgeon has become a standard procedure in the treatment of severe dentofacial dysplasias. Orthognathic surgery, surgery without prior tooth movement, is being replaced by an interdisciplinary approach as the treatment of choice. When a proper tooth-to-denture-base relationship is obtained, an ideal maxillomandibular relationship can be achieved surgically. The quadrilateral analysis enables the practitioner to obtain an individualized skeletal, dental, and soft-tissue assessment of each patient requiring treatment. It determines the direction and extent of the skeletal dysplasia in millimeter measurements and allows the clinician to outline the appropriate surgical orthodontic procedures. The quadrilateral analysis indicates that in a balanced facial pattern a 1:1 ratio exists between the maxillary bony base length (Max.Lth.) and the mandibular bony base length (Mand.Lth.); also that the average of the anterior lower facial height (ALFH) and the posterior lower facial height (PLFH) equals these bony base lengths. Simply stated, the Max.Lth. = Mand.Lth. = (formula; see text) An accurate diagnosis locates the area and quantifies the magnitude of skeletal dysplasia. Then the correct placement of a dentition within the denture bases and the appropriate surgery in the area of dysplasia can produce an individualized, balanced facial pattern.

The diagnostic and conventional treatment techniques used to resolve relative mandibular anterior excess tooth-size problems are reviewed. An alternative solution to these problems, which involves an orthodontic-restorative technique, is described. Specific problems which may be encountered with this technique are also discussed. Three cases are presented, with posttreatment documentation for at least one year. It appears that this technique offers a successful semipermanent treatment for selected cases.

Orthodontists are particularly interested in knowing exactly what skeletal and dental changes are produced by headgear. With headgear and fixed appliances, part of the observed change is due to the headgear, part to the fixed appliances, and part to growth. Since the maxillary traction splint moves the teeth en masse, the dentoskeletal changes are due primarily to the headgear force. Selective mandibular dental changes can be produced by adjusting the mandibular occlusal contacts against the splint. In this study forty-seven patients with maxillary dentoalveolar protrusions and Class II, Division 1 malocclusions were treated with orthopedic headgear that attached to a full-coverage maxillary occlusal splint. Fifty-two patients were selected as a control for evaluation of growth changes versus treatment changes. Lateral cephalograms were taken before and after treatment, and the sagittal skeletal and dental changes were evaluated and quantified. The results of the investigation revealed (1) the establishment of a Class I posterior occlusion, (2) a significant overjet reduction, averaging 4.24 mm, (3) inhibition of vertical development of the maxilla and slight intrusion of the maxillary dentition, (4) overbite reduction by leveling of the mandibular dentition, (5) no indication that mandibular growth is accelerated, and (6) no significant increase in the mandibular plane angle. The maxillary traction splint is an effective means of correcting maxillary dentoalveolar protrusion in growing patients prior to fixed appliance therapy. The second phase of treatment with fixed appliances is necessary for individual tooth positioning and for detailing the occlusion.

The forming of arch wires is time consuming and often relies more on artistic interpolation than on scientific method, thus making the basis of orthodontic practice less precise. For years, various methods of designing arch wires have been tried and have been found inadequate. A new approach is advocated. Based on two decades of orthodontic practice and research, it elucidates a segment concept of arch pattern design, using three common reference measurements of the mandibular arch: canine width, molar width, and the sum of the mesiodistal diameters of the six mandibular anterior teeth. Normative data accumulated from 555 dental patients standardize basic measurements and variants. These data permit development of a finite number of arch patterns, adaptable to virtually all patients. A pattern, once selected, may be used as is or individualized to a specific arch form if necessary. Use of the segment concept might permit a much higher degree of clinical efficacy than that obtained with other methods of arch-wire construction.

The mesiodistal crown diameters were measured in a group of fifty-six male American Negroes from the recruit population at the Great Lakes Naval Training Center and compared with previously reported data on Caucasians from the same population. The results indicate that tooth size is consistently larger in the Negro sample, averaging about 8.4 percent for the over-all maxillary and mandibular dentition, excluding third molars.

Cephalometric head films from a sample of 65 untreated normal persons were evaluated to determine the nature and extent of the normal dentofacial maturation process. Thirty-four parameters were examined in the mixed dentition (9 to 10 years), the early permanent dentition (12 to 13 years), and early adulthood (19 to 20 years). Results showed the importance of maxillary development, particularly in the vertical plane, as it was associated with the amount and direction of sagittal mandibular growth. "Late mandibular growth" was found to be a forward (bite-closing) rotation of the mandible that occurred after the cessation of vertical maxillary growth. Condylar growth amount and direction were influential in determining the degree of sagittal mandibular change. The degree of forward (bite-closing) mandibular rotation was strongly associated with the amount of both maxillary and mandibular molar eruption. Incisor positions were found to remain relatively constant, showing compensations for the amount and direction of skeletal growth. No correlations or predictions of clinical value were found between the cephalometric parameters examined and previously recorded dental-cast variables.

Changes in vertical lip height in relation to dental height, overjet, and overbite of orthodontically treated Class II, Division 1 malocclusions are evaluated through cephalometric roentgenograms of twenty-two male patients. Treatment entailed extraction of the four first premolars and use of the edgewise technique. The results are statistically analyzed, and correlations between various binary combinations are subjected to the 1 percent confidence limit. On the basis of this study, it is concluded that (1) the reduction of overjet, overbite, and dental height with orthodontic treatment is statistically significant at the 1 percent level; (2) the reduction of overjet to that of overbite shows a mean ratio of 1.83 to 1. On the other hand, a reduction of 1 mm, in dental height is accompanied by an average reduction of 3.98 mm. in overjet and of 2.17 mm. in overbite; (3) there is also an insignificant increase in vertical lip height accompanied by a decrease in dental height. The relation is statistically insignificant, however.

In order to overcome the reportedly undesirable side effects of using multilooped arch wires in initial stages of Begg mechanotherapy, a clinical study was conducted in which treatment procedure was modified for the mandibular arch in one group of patients, who received nonlooped or plain mandibular arch wires. This group was closely matched with respect to age, sex, severity of malocclusion, and particularly the amount of anterior mandibular crowding with a group of patients who received multilooped arch wires designed very closely according to the classically prescribed methods. Comparison of the two groups by means of cephalometric measurements of the mandibular incisors at the end of Stage I of treatment demonstrated that the IMPA increased significantly more (p = 0.01) in the multilooped arch wire group. The over-all treatment time was not significantly different in the two groups, although it took longer to resolve the anterior mandibular crowding when plain wires were used. On the basis of this study, it would appear that the use of plain rather than multilooped arch wires in the mandibular arch deserves a favorable consideration in early Begg therapy.

The dental models of seventy-seven orthodontically treated patients were evaluated to determine the contribution of lower incisor tooth dimensions to their alignment many years after treatment. Tooth dimensions included the maximum mesiodistal (MD) and faciolingual (FL) dimensions and the shape ratio represented by MD/FL. Incisor alignment was assessed by means of Little's irregularity index, and all measurements were recorded to the nearest 0.1 mm with modified dial calipers. Multiple regression analysis revealed that the total contribution of all these lower incisor dimensions accounted for only 7.4% of the variability in their alignment, which was not statistically significant. A similar lack of association between lower incisor tooth dimensions and their alignment was found in a sample of eighty-six adults with untreated malocclusions. It therefore appears that the size and shape of the lower incisors do not significantly contribute to their alignment many years after orthodontic treatment.

The strength of the lips was measured with a dynamometer in fifty children, aged 7 to 13 years, with varying types of malocclusion. The lip strength was related to the electromyographically recorded activity of the lips during the lip strength measurements and to bite and facial morphology. The morphology was recorded on dental casts and profile radiographs. The lip strength measurements were found, in duplicate determinations, to have limited reproducibility. There was no correlation between lip strength and the EMG activity of the lips during the recordings. Lip strength was not correlated to dentoalveolar cephalometric variables, including relationship and inclination of the incisors. Nor was there any correlation between lip strength and lip morphology. The value of lip strength measurements seems to be limited, due either to difficulties in recording lip strength or to a small influence of lip muscle forces on the dentition.

This paper describes a method of cephalometric analysis which is currently used by the author in the evaluation and treatment planning of orthodontic and orthognathic surgery patients. In the analysis of a single film, the positions of the maxilla and mandible are related to cranial structures and to each other. Criteria for evaluation of the anteroposterior and vertical positions of the upper and lower incisors are provided, as is the documentation of the standards for each of the measures. In addition, the analysis of serial films is considered and a step-by-step outline of the cephalometric procedure is presented.

Changes in the nasolabial angle of the soft-tissue profile were assessed quantitatively in a serial cephalometric study of fifty treated subjects and forty-three untreated subjects, all of whom had Class II, Division 1 malocclusions. Correlations, simple and multiple regression analyses, and multifactorial analysis of variance were used to examine the changes in the nasolabial angle owing to incisor superius retraction and associated skeletal displacements. There were no significant changes in nasolabial angle because of growth. However, the greater the maxillary incisor retraction, the greater was the increase in nasolabial angle. Increase in the nasolabial angle showed a significant correlation with treatment-related increase in the vertical dimension of the lower face. The soft-tissue profile followed closely the underlying skeletal framework. Extraction and nonextraction treatment procedures did not show significant differences in the changes of the nasolabial angle. Results permit prediction of the changes in nasolabial angle owing to incisor superius retraction in orthodontic treatment.

A study of a sample of 105 Negro children and adolescents, residents of Connecticut, was undertaken to determine the degree of correlation between mandibular tooth size and the size of the canines and premolars. The correlation between the total mesiodistal width of the mandibular permanent incisors and that of the maxillary or mandibular canine and first and second premolars was found to be 0.63 and 0.71, respectively. Further, regression constants were determined in an attempt to estimate the buccal segments from the mandibular incisors.

The effect of treatment with an oral screen was studied in sixteen children with incompetent lips who were compared with a control group of sixteen children who also had incompetent lips. The period of observation was 1 year. The treatment brought about retroclination of proclined maxillary incisors with a resulting decrease in overjet, in the diastema between the incisors, and in arch length. The mandibular incisors proclined somewhat. No change in general intermaxillary relation or in arch width was observed with the treatment. Neither lip morphology nor the electromyographically recorded function of the lips was affected by the treatment. The maximum force that the lips could exert to resist an external force was increased substantially by the treatment. Whether this is of value for the stability of the orthodontic treatment result is not known.

A comparison was made of incisor intrusion achieved in adults and children with deep bite. Facial type was also examined for effect upon intrusion achieved. Fifty-five cases treated with bioprogressive mechanics were studied cephalometrically; subjects included twenty-four adults and thirty-one children. Neither age nor facial type was found to be statistically related to the amount of incisor intrusion achieved in this sample. A method of measuring intrusion at the root apices was devised and was thought to give a more accurate indication of actual bodily intrusion. More external root changes during treatment were observed for adults than for growing children. There was a wide latitude in the amount of intrusion observed in both groups and in all three facial types. Considerable overbite reduction was noted for the sample, and intrusion was found to be but one factor in this.

Angular values of the upper and lower incisors to the APo line were measured in a sample of fifty subjects with clinically acceptable occlusions, ranging from 10 to 14 years of age. Correlations were high between both upper and lower incisor angulations to the APo line and the interincisal angle. The correlation was low between the upper incisor angulations to the APo line and the lower incisor angulations to the APo line. An incisor diagnostic triangle was introduced. This is made up of the interincisal angle and the intersection of the long axes of the upper and lower incisors to the APo line. Incisor diagnostic templates were introduced and their uses as diagnostic and visual aids were enumerated. These templates were constructed by using an idealized linear position of the tip of the lower incisors on the APo line, the upper incisor angulation to the APo line, and the interincisal angle. By relating both incisors to the APo line and to each other through the interincisal angle, the orthodontist is provided with a simple, specific diagnostic aid. The incisors are positioned in relation to a skeletal reference line (APo) which is more intimately associated with the patient's facial profile than more distant skeletal reference lines or planes, such as sella-nasion, Frankfort horizontal, or the mandibular plane.

There is a clinical, biologic, and biomechanical foundation for simultaneous surgical repositioning of the maxilla, mandible, and chin in a significant proportion of adult and adolescent patients. The restoration of normal jaw function, optimal facial esthetics, and long-term stability are the sine qua non of successful orthognathic surgical procedures to simultaneously reposition the jaws. The key to the achievement of these objectives is to carefully and systematically analyze facial esthetics, establish esthetic priorities, and then coordinate and implement them through the use of cephalometric planning and occlusal studies. By meticulous and precise surgical technique, properly programmed, coordinated, and sequenced with efficient presurgical and postsurgical edgewise orthodontic therapy, and systematic postsurgical neuromuscular rehabilitation, the maxilla, mandible, and chin can be simultaneously repositioned with relatively few postoperative complications or sequelae. This article purposes to elucidate on the indications for two-jaw surgery and describe a simplified clinical-cephalometric analysis for orthognathic surgery. Representative case reports are presented and discussed to illustrate the esthetic, orthodontic, and surgical treatment objectives. The basic problems involved in diagnosis and treatment planning of patients who require two-jaw surgery are discussed as well.

To test the hypothesis that preeruptive tooth positions and dental arch parameters might forecast crowding changes, a sample of 47 aboriginal children (26 males, 21 females) was selected stringently on the basis of Class 1 characteristics and an untreated dentition unaffected by caries or attrition. Crowding scores, radiographic relationships of 765E, and dental arch dimensions were evaluated for the mixed dentition (Stage 1, 8.91 +/- 1.05 years) and earliest emergence of the permanent dentition (Stage 2, 12.48 +/- 0.97 years). Changes between the stages were calculated and the sample was divided into two groups, according to an increase (Group 1) or decrease (Group 2) in incisor and canine crowding. Multivariate and multiple regression analyses were used to identify predictors (Stage 1 radiographic and dental arch parameters) of incisor and canine crowding behavior. Dental arch form and tooth size were important factors in measuring the amount of incisor or canine crowding at Stage 1 and Stage 2. Neither the radiographic nor the dental arch predictors proved useful in forecasting crowding changes. Group 2 dental arches tended to be initially narrower, shallower, and more crowded; however, they showed greater molar and canine width expansion and lessened arch depth reduction than Group 1 cases. Many cases showed a reduction in canine crowding from mixed to permanent dentition. This appeared to be largely independent of the observed incisor crowding. Sexual, racial, and individual variations in dentofacial pattern reinforce the need to carefully consider interceptive extraction or space-regaining therapy for each patient because of the unpredictability of crowding behavior during the transition from mixed to permanent dentition.

To summarize, the soft-tissue profile can vary in many ways and still be in balance and harmony. There is a wide range of acceptability regarding soft-tissue chin position in the profile. Both the lips and the chin should line up near the H line, but we need to look at the upper lip from a different perspective or in its relation to a line perpendicular to the Frankfort plane and tangent to the vermilion border to be certain that we are planning the best possible lip support for the case at hand. The H angle, allowing a few degrees for soft-tissue thickness variability, must increase as the basic skeletal convexity increases, and as the convexity increases, the lower incisors will need to be left farther forward than in a straight or concave skeletal profile. A thick integumental covering in the chin area can also effectively align the lower facial profile where lower incisors are farther forward than we are accustomed to seeing them. This principle can also be applied by surgically moving the bony chin forward until the three key soft-tissue points line up. Because there are wide variations in skeletal convexity, standardizing the position of the lower incisor to its apical base support as measured in the Frankfort mandibular incisor angle fails to recognize that upper incisors can be retracted too far, leaving a "streamlined" upper lip which is not esthetically pleasing. Locating the lower incisor in relation to the expected point A to pogonion line is somewhat better but still fails to recognize the wide range of variability in the thickness of the lips and soft-tissue chin. We must also guard against "dishing" those cases having good facial balance with quite normal skeletal convexity and only 5 mm or 6 mm of lower arch length discrepancy. Finally, it is completely practical as a treatment-planning procedure to approach the proposed orthodontic changes from a soft-tissue analysis perspective, making changes only to the point where the best possible soft-tissue profile is established, and then compute the tooth movement necessary to develop ideal profile relationships. The visualized treatment objective, or VTO, is the vehicle that I use to accomplish this.

A cephalometric study, with particular emphasis on incisor pattern, was carried out on thirty Norwegian children with clinically excellent occlusion in the young permanent dentition. The material was selected from a sample of all 12-year-old children within a particular geographic area (Nittedal) of Oslo. The frequency of ideal occlusion was 5.3 percent. A computer-based method of cephalometric analysis was used. The findings indicated that persons with untreated ideal occlusion tended to have a particular facial morphology and dental pattern. More precisely, they were likely to be brachyfacial (horizontal), with somewhat procumbent incisors and a small interincisal angle. Only one patient had dolichofacial (high-angle) characteristics. On average, the lower incisors were 2.5 mm. in front of the APo plane (S.D. 1.7). Remarkably, the lower incisors were not behind the APo plane in any single case with ideal occlusion. Clearly, the lower incisors were clinically significantly more protruded and proclined than those described in previous studies on Scandinavian children and were, in fact, even slightly more procumbent than the Ricketts and Steiner standards. The similarity, with regard to both incisor position and skeletal pattern, of the present findings to some recent studies on American Caucasian children with normal occlusion is stressed. The significance of the observations is discussed in relationship to considerations in orthodontic treatment planning.

A group of patients who had undergone an oblique vertical ramus osteotomy for correction of mandibular protrusion was examined 2 years postoperatively in order to clarify whether the treatment resulted in vertical changes of the front teeth. 1. The results indicate an extrusion of both the upper and lower anterior teeth, as the distance from the upper and lower incisors to the NL and ML lines increased postoperatively (0.3 to 2.3 mm.). 2. The clinical crown height increased (0.3 to 0.4 mm.). 3. The root length decreased (0.5 to 0.9 mm.). 4. There were only insignificant changes in the height of the interproximal marginal bone. 5. There was no significant correlation between the changes in crown height and the amount of tooth extrusion; nor was there any correlation between these changes and the changes in mandibular inclination or root length reduction.

In this exhaustive review, a number of parameters related to maxillary and mandibular second molar extractions are discussed. The parameters reviewed include the timing of extractions and the effect of extractions on third molar eruption, posterior interdigitation, and incisor imbrication. The advantages and limitations of this procedure are outlined. The available information strongly suggests that the extraction of second molars relieves crowding in the posterior part of the arch, causes faster eruption of third molars, and diminishes the number of unerupted and/or impacted third molars. Consideration of the decrease in the number of impacted third molars after second molar extraction should be balanced with the fact that the extracted teeth are usually sound and are unimpacted. In addition, the third molars that do erupt frequently are poorly angulated and/or in poor contact with the first molars. This will necessitate an additional "late" period of fixed-appliance therapy to bring these teeth into good occlusion.

This study examined the effect of lingual root torque during the third stage of Begg treatment upon the maxillary central incisor, hard-tissue Point A, and soft-tissue Point A. Lateral cephalograms were taken, at the beginning and end of Stage III, of eighteen patients undergoing Begg treatment. Linear and angular measurements were made in an attempt to find the anteroposterior changes which occurred in the above structures as well as the superior-inferior changes which occurred in the maxillary first molar and the maxillary central incisor. It was found that the apex of the maxillary incisor, Point A, and soft-tissue Point A moved posteriorly a significant amount following Stage III mechanics. Also, the incisal edge of the maxillary central incisor moved anteriorly and extruded significantly. Weak correlations between hard- and soft-tissue changes may be due to changes in thickness of the upper lip related to growth and to growth of the nose.

Changes in dental arch size and form were assessed by means of univariate and multivariate analysis in a longitudinal study of children between 2 and 10 years of age. The multivariate analysis served to assess the arches as a biologic whole rather than as a series of independent dimensions. Dental arches do not seem to undergo a steady rate of change up to the age of 10 years. In the arches anterior to the first permanent molars, peaks of growth occur between 2 and 3 years and 7 and 8 years in the maxilla, and between 2 and 3 years and 5 and 6 years in the mandible. In the arches, including the first permanent molars, peaks of growth occur between 6 and 8 years in the maxilla and between 9 and 10 years in the mandible.