Increase In Anterior Facial Height Research Articles

Skeletal stability following miniplate fixation after bilateral sagittal split osteotomy for mandibular advancement

Skeletal stability after monocortical miniplate fixation of bilateral sagittal split osteotomies to advance the mandible was evaluated in 20 patients. Three angles and four linear measurements were analyzed on lateral cephalometric radiographs before surgery, immediately after surgery, and at least 6 months after surgery. The mean horizontal advancement at pogonion was 5.0 mm; 6 months after surgery the advancement increased 0.3 mm because of occlusal settling. The mean lengthening of the distance gonion to menton was 5.8 mm and a relapse of 0.3 mm (5.2%) was found. The mean increase of anterior facial height measured at long-term follow-up was 3.6 mm. This study shows that fixation of the advanced mandible with intraorally applied monocortical miniplates after the bilateral sagittal split osteotomy is a stable procedure.

Anterior skeletal fixation as an adjunct to oblique sliding osteotomy of the mandibular ramus: A cephalometric study

Positional changes of the mandible and upper and lower incisors were studied by means of cephalometric analysis after oblique sliding osteotomy for the correction of mandibular prognathism. In addition to intermaxillary fixation, skeletal fixation between the anterior nasal spine and the chin was used. The patients were followed up for 18 months after surgery. During the fixation period no increase in anterior facial height was observed and at 18 months this had decreased by 2.2 mm. Nevertheless, there was an increase in the mandibular plane angle by 3.8 degrees which mainly occurred during the fixation period. The posterior facial height decreased by 4.0 mm. As to the changes of the incisors these varied between individuals, but the mean values were small. Anterior skeletal fixation prevented increase in anterior facial height and seemed to limit the posterior shortening of the mandible and the extrusion of the mandibular incisors. However, the benefits remained rather limited.

Stability after vertical subconydylar ramus osteotomy for correction of mandibular prognathism

A cephalometric analysis of the positional changes of the mandible and the upper and lower incisors following vertical subcondylar ramus osteotomy was performed on 80 patients. The patients were prognathic without laterognathism or open bite and all the patients had preoperative orthodontic treatment. 40 patients were operated with an intraoral (IVSO) and 40 with an extraoral approach (EVSO). Both groups showed postoperatively posterior rotation of the mandible, shortening of the posterior facial height, increase in anterior facial height and extrusion of the incisors in both jaws. A significantly greater reduction of posterior facial height was observed in the EVSO-group, but otherwise the 2 groups did not reveal any statistically significant positional differences. The material was sub-divided into 2 groups 1 with ( n = 32) and one group without ( n = 48) extra skeletal (nasomandibular) fixation in addition to the intermaxillary fixation. Significantly less positional changes of the incisors and less increase of anterior facial height was found in the group with skeletal fixation, but the influence on other skeletal alterations was limited. After release of the intermaxillary fixation, the only difference between the groups was intrusion of the earlier extruded incisors, most pronounced in the group without skeletal fixation.

Changes in facial dimensions associated with the use of forces to retract the maxilla

Legitimate questions exist concerning the degree to which routine orthodontic treatment alters face form. To the extent that such alterations do occur, the delivery of different vectors should result in different sorts of skeletal change. In this study, we have attempted to discern and quantify differences in the rates of change of nine linear measures of mandibular and facial proportions during the course of Phase 1 treatment for the correction of Class II mixed-dentition malocclusion. The analysis took the form of a series of computer-conducted tests performed upon a previously reported tape-stored numerical data base which had been constructed earlier by digitizing pre- and posttreatment lateral cephalograms for a large group of Class II subjects. Rates of change for the nine linear measures were computed separately for samples of subjects treated with cervical face-bow, high-pull face-bow, and activator type intraoral appliances as well as for a control group of untreated Class II subjects. Statistically significant between-treatment differences which we believe are large enough to be of clinical importance were detected for several measures. As compared to the control group, a statistically significant rate of increase in condyle-pogonion distance was found in the intraoral group. Such an observation is consistent with the hypothesis of treatment-associated alteration of growth pattern in the region of the condyle. To our considerable surprise, the cervical group exhibited a similar statistically significant rate of increase in condyle-pogonion distance which is as yet unexplained. In general, rates of increase in measures of anterior face height had higher values in the cervical group than in the control group, implying that consideration should be given to avoiding the use of this treatment modality in patients for whom facial elongation during treatment would be undesirable. The cervical group also exhibited a statistically significant rate of increase in ramus height. Such an effect would tend to keep mandibular plane orientation relatively unchanged in the presence of increase in anterior face height, helping to explain our previously reported findings as to the relative constancy of mandibular plane angle. In the high-pull-treatment group, rates of increase in ramus height and condyle-pogonion distance were significantly lower than those in the control group and rates of increase in lower face height and anterior face height were significantly lower than those in the cervical group. In all three treatment groups, the rate of increase in mandibular body length was less than in the untreated control group, though only in the cervical group was this effect large enough to be statistically significant.

Patterns of change in mandibular and facial shape associated with the use of forces to retract the maxilla

A method is presented for generating simplified graphic-numeric representations of patterns of change in craniofacial size and shape through time. The procedure uses as input any desired set of linear head film measurements made along different directions of biologic interest at different time points. By a simple arithmetic operation, the rate of change of each measure between two time points is expressed as a proportion of the measure's original value. The proportions for the several measures are then re-expressed in terms of a common reference standard yielding a numerical pattern of change through time. This pattern can be used to distinguish regular enlargement of the structure (change in size) from disproportionate enlargement (change in shape). Using this method, we have examined as a unified entity the data for the nine linear measures of mandibular and facial change which were considered separately in the preceding article. Between-treatment differences in patterns of change among groups of measures have been demonstrated somewhat more clearly than was possible with the conventional univariate analyses which we had performed previously. An important general observation is that the rate of increase in the reference measure, sella nasion distance, is smaller than that of any of the other measures with the exception of pogonion-menton. This strongly corroborates the notion that there is far more “downward” than “forward” displacement of facial structures during the developmental stage being studied. A second general observation is that in each of these four groups of Class II subjects, lower face height values are greater as compared to upper face height than is usually considered to be the case in more nearly “ideal” subjects. But, to a large extent at least, this finding is an artifact of the way in which we measure lower face height. This is because when lower face height is defined as the distance from ANS to menton, the more menton is retruded with respect to the facial profile, the longer the measured value will become and the larger its undesired horizontal component will be. The most striking finding of pattern of change in the cervical group is that all measures which have a major vertical component appear to increase relative to the reference standard at rates greater than those observed in the untreated control sample. The largest rate of increase among the mandibular measures is that for ramus height. Such a change would tend to keep the mandibular plane orientation relatively unchanged in the presence of the observed increase in anterior face height. The most striking finding in the high-pull face-bow group as compared to the untreated control group is the reduction in the rate of increase in lower face height while the rate of change of total face height remains essentially unaltered. The most parsimonious explanation for these apparently contradictory findings is that the reduction in the lower face height value in the high-pull group results from restraint upon the forward movement of ANS rather than upon the downward movement of menton. Perhaps the most interesting finding in the intraoral group is the observation that condylepogonion distance increases relative to sella nasion distance at a much more rapid rate than in the control group. Concurrently, the analogous values for mandibular body length are lower in the high-pull group while those for ramus height are higher. Taken together, these findings argue strongly that the intraoral treatment does, in fact, produce alterations in biologic activity in the region of the condyle. The observed patterns of change in the mandible appear to be generally similar in the control group and the high-pull face-bow group on the one hand and in the intraoral group and the cervical group on the other hand. The similarity between the cervical group and the intraoral group is unexplained and is particularly puzzling. The main limitations of the transformational method that we have used here arc that it is inappropriate for use in individual case analysis, that it contains no measure of within-treatment variability, and that anomalies in the reference measure may cause systematic errors in the values of all other measures when growth rate coefficients are employed. Used with due regard for these limitations, we believe that the method is a useful addition to the repertoire of quantifying tools in roentgenographic cephalometry.

A cephalometric evaluation of high-pull molar headgear and face-bow neck strap therapy

The effects of two different extraoral appliances were evaluated over a 1-year period. Of the thirty-seven cases selected for study, twenty were treated with a face-bow neck strap and seventeen were treated with a high-pull molar headgear. Patients ranged in age from 10.10 to 16.6 years and averaged 13.4 years. The appliances exerted less than 600 Gm. of force per side and were worn for 12 to 16 hours per day. All cases were fully banded, and extraction and nonextraction treatment were included. An analysis of pretreatment data revealed a high degree of selection. Patients selected for high-pull treatment generally exhibited larger anterior face heights, steeper mandibular plane angles, and a greater amount of tooth eruption of the upper first molars than the patients selected for neck strap therapy. A control group of ten untreated subjects was matched to each treatment group to permit assessment of the impact of treatment on growth. Relative to normal growth, treatment with face-bow neck strap traction tended to direct the maxilla and mandible downward and backward. The palatal plane was lowered anteriorly and point A was retracted. The maxillary molars were extruded, and concomitantly an increase in anterior face height and mandibular plane angle was observed. On the other hand, the high-pull molar headgear traction resulted only in increased mandibular molar eruption. However, there was also a nonsignificant tendency for point A to be held back and for lower anterior face height to increase. The comparison of the two treatment samples revealed that the functional occlusal plane was tipped down at the back as the maxillary molars were more extruded in the neck strap sample. In the high-pull sample, the functional occlusal plane was unchanged and the mandibular molars were more extruded than they were in the neck strap group.

The great problem in malocclusion of the teeth of the types of Class II

The aim of this work was to perform a cephalometric analysis of the craniofacial parameters and natural head posture of mouth-breathers compared with control subjects, and to study the relationship between nose-breathing and the vertical dimension.The headfilms taken at start of treatment of 53 cases (28 girls, 25 boys) aged 9 to 30 who consulted the dento-facial orthopedic department of the Ibn Rochd Casablanca dental consultation and treatment center were studied.Among the mouth-breathers, we noted mandibular retrusion (SNB) in association with posterior rotation and more pronounced tilt of the mandibular plane (PP-MP) compared with the controls (P < 0.05), a disproportionate increase in anterior face height and a lessening of posterior face height (hyperdivergence). These increases in anterior face height are often associated with retrognathism (and open bite).Our study has shown that there are cephalometric differences between mouth-breathers and nose-breathers. There are several studies in the literature with results that support ours. Collaboration between the pediatric dentist, the orthodontist and the ENT specialist is important so as to establish an early diagnosis of mouth-breathing in children and initiate appropriate treatment to recreate the best conditions for harmonious development.