The effect of force on craniofacial development

Skeletal and dentoalveolar changes after total maxillary arch distalization using the casted palatal plate vs. buccal miniscrews: A randomized clinical trial

OBJECTIVES

To evaluate treatment changes after total maxillary arch distalization using the casted palatal plate compared with buccal miniscrews.

MATERIAL AND METHODS

This was a randomized, parallel, two-arm, single center trial. Participants were young adults with class II dental relationships and normal or horizontal growth patterns. The patients were treated with total distalization of the maxillary arch and were randomly allocated, according to the anchorage devices, between the plate group and the minivis group. The primary outcomes were sagittal, vertical and angular changes of molars and incisors, while the secondary outcomes were skeletal and soft tissue changes. Outcomes were evaluated on lateral cephalograms and blinding of outcome assessment was implemented. A multivariate analysis of Variance (MANOVA) tests were used and Bonferroni correction for multiple comparisons with P<0.001.

RESULTS

Forty patients (33 females and 7 males; mean age 20±3.1 years) where enrolled. A significant distalization of U6 was observed in both groups (4.33mm in the plate group and 1.88mm in the miniscrews group). It was combined with significant intrusion and non-significant distal tipping of the U6 in the plate group (1.85mm and 3.10°, respectively), while intrusion and distal tipping were non-significant in the miniscrew group (0.8mm and 2°, respectively). Both groups showed significant retraction and palatal inclination without vertical changes of U1. Only the plate group produced significant reduction of ANB and Wits. Upper and lower lips were retracted and the nasolabial angle increased significantly in both groups. There was no significant main effect of the appliance type on the comparison of treatment effects between the two groups (P=0.623). However, univariate comparisons showed that the plaque group showed greater distalization of the U6 (P<0.001).

CONCLUSIONS

Both the casted palatal plate and buccal miniscrews can be viable devices for total distalization of the maxillary arch in the treatment of class II patients. The casted plate may be considered when more extensive distalization is required.

Stability of the Maxillary and Mandibular Total Arch Distalization Using Temporary Anchorage Devices (TADs) in Adults

Distalization with temporary anchorage devices (TADs) is commonly used to resolve crowding and to correct molar relationships in non-extraction cases. The purpose of this study was to quantify the treatment effects and post-treatment stability of total arch distalization with TADs in adults and thereby elucidate the clinical effect of this treatment modality. The subjects of the study were 39 adult orthodontic patients treated with total arch distalization with TADs. Lateral cephalograms and dental casts were taken at pretreatment (T0), post-treatment (T1), and the retention period (T2, 29.3 ± 12.8 months) to evaluate the vertical and horizontal movement of teeth, changes of arch width and molar rotation. It was concluded that even though there was a little relapse in the anteroposterior position of the maxillary and mandibular teeth during retention, there was no obvious relapse in the facial profile. Therefore, the total arch distalization can be used in patients with a moderate amount of arch length discrepancy effectively with stable retention.

Accuracy of 3 Soft Tissue Prediction Methods After Double-Jaw Orthognathic Surgery in Class III Patients

PURPOSE

We aimed to evaluate the accuracy and validity of conventional manual prediction method (CM) and 2-dimensional and 3-dimensional (3D) soft tissue prediction methods for Class III bimaxillary orthognathic surgery patients.

METHODS

Twenty skeletal Class III patients were included in this study. Soft tissue prediction was achieved with a traditional manual technique, 2-dimensional software (Dolphin Imaging, version 11.5), and 3-dimensional software (SimPlant Master, version 16.0) on preoperative lateral cephalometric radiographs and cone beam computurized tomography (CBCT) images and then compared with postoperative lateral cephalometric radiographs obtained at least 6 months after surgery (mean, 11.5 ± 6.77 months). Forty-eight measurements were done to determine the reliability of the methods.

RESULTS

All prediction methods have limited postsurgery prediction accuracy for the subnasal upper lip area. Most of the differences were not more than 3 mm for all study groups, except the 3D software, which predicted the upper lip area to be, on average, 3.08 ± 1.38 mm further back (P < 0.001). Although the conventional method predicted 20 of 48 measurements similar to the final results, the poorest predictions were found at the nasal and labiomental areas (P < 0.001). Two-dimensional software predicted 23 of 48 measurements very close to the final results but made significantly different predictions for the nasolabial and labiomental angles, labrale superius point, and the chin area.

CONCLUSIONS

The 3D method predicted, especially the upper lip area, to be significantly and clinically incorrect, and its soft tissue prediction was insufficient compared with the other 2 methods. The 3D software needs to be updated, especially in evaluating soft tissue A point and upper lip changes after surgery.

Effects of force magnitude on dental arches in cervical headgear therapy

AIM

To study the influence of different force magnitudes on dental arches in cervical headgear (CHG) treatment.

MATERIAL AND METHODS

In this controlled clinical trial, patients (n = 40) were treated with CHG with light (L, 300 g, n = 22) or heavy force (H, 500 g, n = 18) magnitude. Subjects were asked to use CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was raised 10-20 degrees and the inner bow expanded 3-4 mm. Adherence to instructions and force magnitude were monitored with an electronic module (Smartgear, Swissorthodontics, Switzerland). Impressions for study models were taken before (T1) and after (T2) treatment and the study models were scanned into digital form (3Shape, R700 Scanner, Denmark). Measurements were made using the digital models (Planmeca Romexis, Model analyser, Finland).

RESULTS

During the treatment (T1-T2) the upper inter-canine distance increased by 2.83 mm (P = 0.000) and 2.60 mm (P = 0.000) in the L and H force magnitude groups, respectively. Upper inter-molar width increased by 3.16 mm (P = 0.000) and 2.50 mm (P = 0.000) in the L and H groups, respectively. Maxillary total arch perimeter increased by 6.39 mm (P = 0.001) and 6.68 mm (P = 0.001) in the L and H groups, respectively. In the amount of change over time, T1-T2, in the upper arch measurements, no significant difference was found between the groups. Lower inter-canine width increased by 0.94 mm (P = 0.005) and 1.16 mm (P = 0.000) in the L and H groups, respectively; no difference between the groups. Lower inter-molar distance increased by 2.17 mm (P = 0.000) and 1.11 mm (P = 0.008) in the L and H groups, respectively. At the end of the study, upper and lower inter-molar width was larger in the L group than in the H group (P = 0.039 and P = 0.022, respectively).

CONCLUSION

CHG therapy is an effective method for expanding and releasing moderate crowding of the upper dental arch. The lower arch spontaneously follows the upper arch in widening effects, and minor expansion can also be seen on the lower arch. In the L group, larger inter-molar width was achieved on the upper and lower arch; probably due to better adherence to instructions. Light force is recommended for use in CHG therapy.

Comparison of effects of cervical headgear treatment on skeletal facial changes when the treatment time is altered: a randomized controlled trial

Background

There is a lack of evidence based on longitudinal information in the field of Class II malocclusion management with cervical headgear (CH), especially in a randomized setting.

Objectives

The main objective of this study was to evaluate skeletal facial changes, particularly in vertical dimensions, after Kloehn-type CH treatment in children when the timing of treatment is altered.

Trial design

Prospective, parallel-group, randomized controlled trial.

Methods

Screened children with Class II malocclusion were randomized in 1:1 ratio to two groups of equal size by sealed-envelope randomization: the early group (EG), where active CH treatment was started at the age of 7.8 years, and the late group (LG), where CH treatment was started at the age of 9.5 years. The active treatment was continued until normal Class I occlusion on first molars was achieved. Cephalograms were taken at three different time points. Changes in cephalometric measurements were compared between groups and genders. Blinding was applicable for outcome evaluation.

Results

Of 67 randomized children, 56 completed the study. Upper face height increased during the CH treatment phase, as the parameter N–ANS increased significantly during the active treatments of EG (P < 0.05) and LG (P < 0.05). Also, the parameter NSL–PL increased significantly during the treatment of EG (P < 0.01) and during the treatment of LG (P < 0.01). The Gonial angle decreased significantly in the early CH treatment group compared to the later treatment group (T0–T2: P < 0.01). CH improved the antero-posterior jaw relationship. No harms were encountered.

Conclusions

Although the upper face height increased, the mandible showed anterior rotation after CH treatment. The Gonial angle was significantly decreased in the EG compared to the LG. There were gender-specific differences in both sagittal and vertical dimensions when examining interrelations in dimensional changes. The differences found between the early and later treatment groups were not clinically important when the cephalometric results are considered.

Clinical registration

ClinicalTrials.gov (NCT02010346).

Impact of force magnitude on effectiveness in cervical headgear therapy: a cephalometric analysis

Aim

The main aim of this study was to study the impact of different force magnitudes on effectiveness in cervical headgear (CHG) therapy.

Materials and methods

Forty patients were treated with CHG with light (L; 300 g) or heavy (H; 500 g) force in this controlled clinical trial. Patients were asked to wear CHG for 10 hours/day for 10 months. The inner bow of the CHG was expanded (3–4 mm) and the long outer bow bent (10–20 degree) upward in relation to the inner bow. Adherence to instructions and force magnitude in CHG use was monitored by electronic module (Smartgear, Swissorthodontics, Switzerland). Lateral cephalograms were taken before (T1) and after (T2) the treatment and studied with modified Pancherz analysis using a Planmeca Romexis Ceph module (Planmeca, Finland).

Results

In both groups, skeletal and dental effects were seen. The only statistically significant difference in cephalometric analysis was the inclination of upper incisors at T1 (P = 0.010) and at T2 (P = 0.011). In both groups, a reduction in Sella-Nasion- point A (SNA) angle was found: L group T1 82.7degree (SD ± 3.6degree), T2 82.0degree (SD ± 3.5 degree) and H group T1 82.6 degree (SD ± 4.7 degree), T2 81.5 degree (SD ± 4.5 degree), but no statistically significant difference between the groups. Children in the L group used CHG statistically significantly more than those in the H group (10.0 ± 1.5 hour, and 8.3 ± 2.1 hour, respectively, P = 0.002).

Conclusion

Children with lower force CHG seem to adhere better to instructions for CHG use. After 10 months of use, no statistically significant differences were found in dental or skeletal outcome. However, in the H group, the outcome was achieved with less daily hours of use.

Adherence to instructions and fluctuation of force magnitude in cervical headgear therapy

OBJECTIVES

To investigate how patients adhere to instructions and how force magnitude fluctuates and influences the use of cervical headgear (CHG) therapy.

MATERIALS AND METHODS

In this controlled clinical trial, subjects (n = 40) were treated with CHG with light (L, 300 g) or heavy (H, 500 g) force. Patients were asked to wear CHG for 10 hours per day for 10 months (ie, during sleep), but the importance for treatment of wearing CHG also in the evening hours was emphasized. Adherence to instructions and force magnitude in CHG use were monitored by electronic module (Smartgear, Swissorthodontics, Switzerland).

RESULTS

Force magnitude can be set at a certain level, L or H, even if great individual variability is seen in all subjects (0-900 g). Children in the L group used CHG longer per day than those in the H group (9.3 hours ±1.5 hours and 7.8 hours ± 2.1 hours, respectively, P = .002). During evening hours, CHG was used more ( P = .02) in the L group than in the H group. In both groups, CHG was used less in the evening hours during school breaks than in the evening hours during school ( P < .001).

CONCLUSIONS

Children with lower force in CHG seem to adhere better to the instructions for CHG use. Daily rhythm also influences the time of appliance use regardless of force magnitude. The force can be set to a certain magnitude level, even though there is substantial individual variability.

Treating Class II malocclusion in children. Vertical skeletal effects of high-pull or low-pull headgear during comprehensive orthodontic treatment and retention

OBJECTIVES

To evaluate, in Class II malocclusion children, vertical skeletal changes occurring with high- and low-pull headgear during non-extraction comprehensive orthodontic treatment, and retention.

SETTING AND SAMPLE POPULATION

Two groups of thirty Class II malocclusion children (mean age 10.8 years) who had undergone non-extraction comprehensive orthodontic treatment with either high- or low-pull headgear and fixed appliances.

MATERIAL AND METHODS

Retrospective longitudinal study, where pre-treatment, post-treatment and at least 2 year post-retention lateral cephalometric radiographs were analyzed. Comparisons were made concerning changes during treatment and retention in high- or low-pull headgear-treated children. Correlation analyses were carried out investigating changes in vertical cephalometric parameters and pre-treatment vertical facial pattern or type of headgear used.

RESULTS

During treatment, sagittal relationships improved in all children and remained stable during retention. Vertically, in both high- and low-pull headgear groups, the intermaxillary angle as well as the maxillary and mandibular plane angles did not show statistically significant changes during treatment or retention, and large variation was seen between patients. When pooling the whole patient sample, change in the vertical facial pattern was independent of the pre-treatment vertical facial pattern or type of headgear used.

CONCLUSION

When treating Class II malocclusion children non-extraction with high- or low-pull headgear and fixed appliances, changes in vertical skeletal relationships demonstrate wide variation, both during treatment and retention. Dentoalveolar changes brought about by these appliances may not be able to make a predictable difference in vertical skeletal patterns of growing patients.

Dental and skeletal components of Class II open bite treatment with a modified Thurow appliance

INTRODUCTION

Due to the lack of studies that distinguish between dentoalveolar and basal changes caused by the Thurow appliance, this clinical study, carried out by the School of Dentistry--State University of São Paulo/Araraquara, aimed at assessing the dental and skeletal changes induced by modified Thurow appliance.

METHODS

The sample included an experimental group comprising 13 subjects aged between 7 and 10 years old, with Class II malocclusion and anterior open bite, and a control group comprising 22 subjects similar in age, sex and mandibular plane angle. Maxillary/mandibular, horizontal/vertical, dental/skeletal movements (ANS, PNS, U1, U6, Co, Go, Pog, L1, L6) were assessed, based on 14 landmarks, 8 angles (S-N-ANS, SNA, PPA, S-N-Pog, SNB, MPA, PP/MPA, ANB) and 3 linear measures (N-Me, ANS-Me, S-Go).

RESULTS

Treatment caused significantly greater angle decrease between the palatal and the mandibular plane on the experimental group, primarily due to an increase in the palatal plane angle. ANB, SNA and S-N-ANS angles significantly decreased more in patients from the experimental group. PNS was superiorly remodeled. Lower face height (ANS-Me) decreased in the experimental group and increased in the control group.

CONCLUSIONS

The modified Thurow appliance controlled vertical and horizontal displacements of the maxilla, rotated the maxilla and improved open bite malocclusion, decreasing lower facial height.

Craniofacial morphology in pediatric patients with persistent obstructive sleep apnea with or without positive airway pressure therapy: a cross-sectional cephalometric comparison with controls

INTRODUCTION

Compression on the midface with nasal mask-delivered positive airway pressure (PAP) therapy in growing patients might contribute to midface retrusion. The objective of this study was to investigate the association between long-term PAP use and craniofacial morphologic pattern in children with persistent obstructive sleep apnea.

METHODS

Images generated with cone-beam volumetric imaging were used to complete lateral cephalometric analyses of anteroposterior projection of the midface region. The study group included 12 subjects (10 boys, 2 girls; mean age, 9.0 years) who used PAP therapy for at least 6 months and at least 6 hours per night. Measurements from this group were compared with those of a control group of 11 subjects (5 boys, 6 girls; mean age, 9.6 years) with obstructive sleep apnea who did not have PAP. Measurements were taken at 1 time point.

RESULTS

No significant differences were identified between the groups for any cephalometric variable. Multivariate linear regression analysis also did not identify a significant association between the number of months of PAP therapy and the cephalometric variables. Cephalometric data for both groups were pooled for comparison with appropriate published normative values for age and sex. Anterior cranial base length, overall anteroposterior length of the maxillary base, and mandibular body length were significantly shorter than normal in the subjects compared with published normative values.

CONCLUSIONS

No association was demonstrated between midface projection and PAP use in growing patients. When compared with normative data for anterior cranial base, children with obstructive sleep apnea had shorter maxillary and mandibular lengths.

Cephalometric effects of the use of 10-hour Force Theory for Class II treatment

OBJECTIVE: This study aimed to evaluate the cephalometric effects promoted by the orthodontic treatment of Class II malocclusion patients with the use of the 10-Hour Force Theory, that consists in the use of fixed appliances with 8 hours a day using a cervical headgear appliance and 16 hours a day using Class II elastics, 8 hours on the first mandibular molar and 8 hours in the second mandibular molar. METHODS: Sample comprised 31 patients with mean initial age of 14.90 years, final mean age of 17.25 years and mean treatment time of 2.35 years. The lateral cephalograms in pre-treatment and post-treatment stages were evaluated. Evaluation of cephalometric changes between initial and final treatment phases was performed by paired t test. RESULTS: The cases treated with the 10-Hour Force Theory presented a slight restriction of anterior displacement of the maxilla, increase in the effective length of the mandible, significant improvement of the maxillomandibular relationship, significant increase in anterior lower face height, distal tipping of the maxillary premolar crowns, extrusion and distal tipping of the roots of maxillary molars, significant proclination and protrusion of mandibular incisors, significant extrusion and mesialization of mandibular molars, besides a significant correction of the molar relationship, overjet and overbite. CONCLUSION: The use of the 10-Hour Force Theory in treatment of Class II malocclusion provided satisfactory results.

Effects on the maxilla and cranial base caused by cervical headgear: a longitudinal study

Objectives: The aim of this study is to test the possible orthopedic effects of cervical headgear on the cranial base and maxilla. Study design: a sample consisting of 79 subjects with skeletal class II malocclusion was divided into two groups. The experimental group was made up of 41 patients all treated with cervical headgear. The control group included a total of 38 non-treated patients. Each one of these groups was then subdivided according to age into one of three groups: prepubescent, pubescent or post-pubescent. Cephalometric parameters were compared in both groups in order to measure the cranial base angle and the vertical and sagittal position of the maxilla. Additionally, cephalometric superimpositions taken at the beginning and end of the study were compared. Results: results revealed significant differences in the cranial base angle and in the SNA angle (p<0.05). However, no differences were observed in the variables that measure the maxillomandibular relationship. While no changes were noted in the palatal plane slope, a flattening of the cranial base was found caused by the cervical headgear, in addition to a retrusion of point A that does not mean there was a reduction in the maxillomandibular relationship. Conclusions: cervical headgear treatment induces cephalometric flattening of the cranial base and a decrease of the SNA angle.

Key words:Orthodontics, cervical headgear, class II treatment, cephalometry, superimposition.

Molar distalization with a pendulum appliance K-loop combination

SUMMARY

The aim of this study was to evaluate the dentoalveolar effects of a pendulum appliance supported buccally by a K-loop, and to compare these with a cervical headgear (CHG) group. The records of 30 patients with skeletal Class I and dental Class II malocclusions were divided in to two groups: Patients in group 1 (seven females and eight males; mean age, 15.0 +/- 3.4 years) were treated with a pendulum appliance supported with a K-loop buccally, while in group 2 (10 females and 5 males; mean age, 14.2 +/- 2.9 years), the patients were treated with CHG. Standardized lateral cephalograms and study models were taken at the beginning of treatment (T0) and at the end of distal molar movement (T1). T0-T1 changes within the groups were analysed with a paired t-test, and between the groups with a t-test. The mean amount of distalization was 4.53 +/- 1.46 mm in group 1 and 2.23 +/- 1.68 mm in group 2. The mean amount of distal tipping for group 1 was 5.13 +/- 4.90 degrees; the mean amount of mesial tipping for group 2 was 0.80 +/- 2.27 degrees. Intrusion and mesiobuccal rotation of the maxillary molars were achieved in both groups. In group 1, the amount of labial protrusion and tipping of the maxillary incisors was not statistically significant. In group 2, palatoversion and retrusion of the maxillary incisors was statistically significant (P < 0.01 and P < 0.001, respectively). The two major disadvantages of intraoral appliances, which are distal tipping of molars and loss of anchorage at the anterior teeth, were significantly decreased with the use of a pendulum appliance K-loop combination.

[Are extraoral forces justified in the early treatment of Class II malocclusions?]

First phase class II early treatments are able to restore a correct growth. DAC (Distal Active Concept) is an early fixed treatment using class II elastics, coils and springs. The aim of this retrospective study was to evaluate short and long term dental and skeletal effects of head-gear applied on upper first molars associated to class II elastics and to compare our results to a sample treated with early DAC. Headgear group included 37 subjects. DAC group included 100 subjects. Cephalometric values came from Pancherz's and Tweed's analysis. Lateral head-films were analysed at t1 (before early active treatment), at t1' (after early active treatment) and at t2 (before second stage in permanent dentition). T-tests were performed to compare the groups. Results were quite similar for these two types of treatment showing nevertheless greater mandibular answer in DAC group. Only a prospective randomised study would be able to precise these observations.

Comparison of the effects produced by headgear and pendulum appliances followed by fixed orthodontic treatment

This study compared the effects produced by two different molar distalizers, namely cervical headgear (CHG) and the intraoral pendulum appliance, associated with fixed orthodontic appliances. The headgear group comprised 30 patients (19 females, 11 males), with an initial age of 13.07 years [standard deviation (SD) = 1.3], treated with CHG and fixed orthodontic appliances for a mean period of 3.28 years, and the pendulum group 22 patients (15 females, 7 males), with initial age of 13.75 years (SD = 1.86), treated with the pendulum appliance followed by fixed orthodontic appliances for a mean period of 4.12 years. Lateral cephalograms were taken at the start (T1) and on completion (T2) of orthodontic treatment. The pendulum and CHG groups were similar as to initial age, severity of the Class II malocclusion, gender distribution, initial cephalometric characteristics, and initial and final treatment priority index (TPI). Only treatment time was not similar between the groups, with a need for annualization for data for the pendulum group. The data were compared with independent t-tests. There was significantly greater restriction of maxillary forward growth and improvement of the skeletal maxillomandibular relationship in the CHG group (P < 0.05). The maxillary molars were more mesially tipped and extruded and the mandibular molars more uprighted in the CHG group compared with the pendulum group (P < 0.05). There was more labial tipping of the mandibular incisors and greater overbite reduction in the pendulum group. The pendulum appliance produced only dentoalveolar effects, different from the CHG appliance, which restricted maxillary forward displacement, thus improving the skeletal maxillomandibular relationship.

Cephalometric evaluation of Class II malocclusion treatment with cervical headgear and mandibular fixed appliances

The present study aimed to evaluate the cephalometric changes in Class II patients treated exclusively with cervical headgear (CHG) in the maxillary arch and fixed appliances in the mandibular arch as compared with a control group. The sample comprised 82 lateral cephalograms obtained pre- (T1) and post- (T2) treatment/observation of 41 subjects, divided into two groups: group 1-25 Class II division 1 patients (20 females and five males), with a mean pre-treatment age of 10.4 years, treated for a mean period of 2.5 years and group 2-16 Class II untreated subjects (12 females and four males), with a mean initial age of 9.9 years, followed for a mean period of 2.2 years. Treatment changes between the groups were compared by means of t-tests. The results showed restriction of maxillary forward displacement and also a restriction in maxillary length growth, improvement in the maxillomandibular relationship, restriction of mandibular incisor vertical development, reduction in overjet and overbite, and improvement in molar relationship. It was concluded that this treatment protocol corrected the Class II malocclusion characteristics primarily through maxillary forward growth restriction.

Treatment and posttreatment changes with combined headgear therapy

OBJECTIVE

To determine the effects of combined headgear treatment in high-angle patients and to evaluate the differences 2 years after treatment.

MATERIALS AND METHODS

The study material consisted of lateral cephalograms of 21 patients (13 girls and eight boys; mean age 10 years 3 months) with Class II dental relationship. Only extraoral combined traction that was applied to maxillary first molars was used in the treatment of all patients. The patients were instructed to wear the appliance 20 hours per day until the molar relationship was corrected. The treatment time was approximately 5 months. At the beginning (T0), at the end (T1), and approximately 2 years after (T2) combined headgear treatment, lateral cephalometric radiographs were obtained.

RESULTS

SNA and ANB angles and convexity decreased significantly during treatment (T0-T1; P<.05 and P<.01, respectively), and the net changes (T0-T2) in ANB angle and convexity were also found to be statistically significant (P<.01). During treatment, significant distal movement was found in the upper first molar, and the second premolar and molar were also distalized significantly (P<.001). At the end of 2 years, there was a significant mesial migration of the upper molars and the second premolar during the posttreatment period, but all of them were positioned more distally compared to the beginning of treatment (P<.001). The decrease in molar relation was statistically significant during the T0-T1 and T0-T2 periods (P<.001).

Dentoskeletal changes induced by the Jasper jumper and cervical headgear appliances followed by fixed orthodontic treatment

INTRODUCTION The objective of this controlled clinical study was to compare the dentoskeletal effects of the Jasper jumper with those of cervical headgear, when both are used with edgewise appliances to correct Class II Division 1 malocclusion.

METHODS

Lateral cephalograms of 75 patients were divided into 3 groups of 25. The control group included untreated Class II children with an initial mean age of 11.82 years (range, 9.35-14.84 years); they were followed without treatment for a mean period of 1.95 years (range, 0.90-3.95 years). The Jasper jumper group had an initial mean age of 11.86 years (range, 9.45-14.94 years); they were treated for a mean period of 1.96 years (range, 0.93-3.98 years). The cervical headgear group had an initial mean age of 12.29 years (range, 9.95-15.24 years); they were treated for an average of 1.88 years (range, 0.95-3.95 years). Comparison of the initial measurements showed that the 3 groups were similar at pretreatment, thus allowing direct comparisons. Analysis of variance (ANOVA) and the Tukey test were applied for comparison of the groups.

RESULTS

Different appliances yielded specific effects on several components (skeletal and dentoalveolar) evaluated. Anterior maxillary growth was significantly restricted by the cervical headgear. Mandibular growth was similar in all 3 groups, although it was slightly greater in the Jasper jumper group. The experimental groups had similar improvements in maxillomandibular relationshipd. The pattern of craniofacial growth was not significantly different between groups. The most significant effect on the maxillary dentoalveolar component was retrusion of the maxillary incisors by the cervical headgear. The effects observed for the Jasper jumper group were primarily related to the mandibular dentoalveolar component, including labial tipping and protrusion of the mandibular incisors, and mesial movement and extrusion of the mandibular molars compared with the control group.

CONCLUSIONS

The headgear appliance corrected the Class II malocclusion mostly by anterior maxillary restriction and maxillary dentoalveolar effects. Correction of the Class II malocclusion with the Jasper jumper appliance was largely due to mandibular dentoalveolar effects rather than skeletal effects.

Cervical Headgear Effects on the Morphology of the Cervical Vertebrae and Cervical Posture

OBJECTIVE

To test the hypothesis that use of cervical headgear has an important effect on the morphology of the cervical vertebrae and cervical posture.

MATERIALS AND METHODS

The material consisted of pretreatment and posttreatment lateral cephalograms and initial hand-wrist films of 30 subjects who were receiving cervical headgear therapy. Preobservation and postobservation control cephalograms and preobservation hand-wrist films of 15 untreated subjects served as controls. The average treatment time for the treatment group was 9.06 +/- 1.02 months, and the average observation period for the control group was 10.0 +/- 1.1 months. A paired t-test was applied to compare the changes occurring during the examination and observation periods in both groups. In addition, Student's t-test was performed to assess the differences between the groups.

RESULTS

The results of the paired t-test showed that within each group there were statistically significant differences in the majority of measurements concerning the morphology of the cervical vertebrae, whereas the measurements concerning cervical posture showed no significant changes in either group. According to the results of the Student's t-test, however, no statistically significant changes between the treatment and control group were present except with regard to two measurements.

CONCLUSIONS

Changes in the cervicovertebral morphology in the treatment group were achieved more by growth than by cervical headgear treatment. Although high individual variations were found in postural variables, cervical posture did not change over a period of 9 months either in the treatment group or in the control group.

Remodeling the dentofacial skeleton: the biological basis of orthodontics and dentofacial orthopedics

Orthodontic tooth movement is dependent upon the remodeling of the periodontal ligament and alveolar bone by mechanical means. Facial sutures are also fibrous articulations, and by remodeling these joints, one can alter the positional relationships of the bones of the facial skeleton. As might be expected from the structure and mobility of the temporomandibular joint (TMJ), this articulation is more resistant to mechanical deformation, and whether functional mandibular displacement can alter the growth of the condyle remains controversial. Clinical investigations of the effects of the Andresen activator and its variants on dentofacial growth suggest that the changes are essentially dento-alveolar. However, with the popularity of active functional appliances, such as the Herbst and twin-block based on 'jumping the bite', attention has focused on how they achieve dentofacial change. Animal experimentation enables informed decisions to be made regarding the effects of orthodontic treatment on the facial skeleton at the tissue, cellular, and molecular levels. Both rat and monkey models have been widely used, and the following conclusions can be drawn from such experimentation: (1) Facial sutures readily respond to changes in their mechanical environment; (2) anterior mandibular displacement in rat models does not increase the mitotic activity of cells within the condyle to be of clinical significance, and (3) mandibular displacement in non-human primates initiates remodeling activity within the TMJ and can alter condylar growth direction. This last conclusion may have clinical utility, particularly in an actively growing child.

Effects of Cervical Headgear on Overbite against the Background of Existing Growth Patterns

Objective: To test the questions “Does cervical headgear treatment necessarily lead to a reduction of overbite?” and “Are there differences in treatment results due to different growth patterns or the initial overbite?”

Materials and Methods: Initial and intermediary casts of 247 patients who had been treated exclusively with headgear were analyzed for changes in the occlusal relationship of the first molars and overbite. Orthodontic treatment consisted of the application of cervical headgear with nonangulated external arms applied at a force of 3.5–4.0 N. Only patients showing dental changes of occlusal relationship ≥4 mm during at least a 6-month treatment duration were selected. Growth patterns were identified by the y-axis values measured on lateral cephalograms obtained at study entry. Six groups were formed on the basis of these growth patterns.

Results: Headgear treatment induced bite deepening in patients with vertical growth patterns and bite opening in patients with horizontal growth patterns. Further subdivision based on initial overbite revealed bite deepening in patients with small initial overbite and bite opening in patients with large initial overbite. These differences were statistically significant (P &lt; .05). Only minor changes were observed in patients with an initial overbite of 3–4 mm.

Conclusions: Overbite reductions were not dependent on the growth pattern. Orthodontists should expect bite opening in deep-bite situations and bite deepening in open-bite situations. However, initial overbite situations of 3–4 mm should not be expected to change in a significant way.

The role of cervical headgear and lower utility arch in the control of the vertical dimension

INTRODUCTION

This study was carried out to evaluate the treatment changes in skeletal and dental parameters in growing patients.

METHODS

The sample consisted of 24 subjects with Class II Division 1 malocclusion. Half of the patients were treated with cervical headgear alone (group C, n = 12), and the other half received a combination of cervical headgear and lower utility arch (group CU, n = 12). The treatment groups were compared with a matched untreated control group (n = 12). The mean ages of the subjects at the beginning of the study were 8.85 +/- 1.19 years in group C, 9.23 +/- 0.76 years in group CU, and 8.62 +/- 0.78 years in the control group. The cervical headgear was used with an expanded inner bow and a 15 degrees to 20 degrees upward bend of the longer outer bow, worn 12 to 14 hours a day, with a force of 450 to 500 g per side. The lower utility arch was designed as described in the bioprogressive technique. Treatment changes were assessed on lateral cephalometric radiographs.

RESULTS

The cervical headgear produced Class II correction through maxillary orthopedic and orthodontic changes. Anterior face height increased more in the treatment groups than in the control group. The treatment groups also displayed statistically significant increases in ramus height. Due to these effects, mandibular plane orientation stayed relatively unchanged. There was no opening rotation of the mandible in the treatment groups. The lower utility arch produced intrusion and lingual tipping of the mandibular incisors and distal tipping without extrusion of the mandibular molars. The treatment groups showed significant anterior descents of the palatal plane. Maxillary molar total extrusion produced by cervical headgear treatment was an average of no more than 1 mm as compared with the control group. The utility arch did not appear to influence mandibular rotational response.

Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system

INTRODUCTION

It is now possible to predictably move maxillary molars distally in nongrowing patients with the skeletal anchorage system (SAS) and to improve malocclusions without having to extract the premolars and regardless of the patient's compliance. The purposes of this study were to investigate the amount of distal movement of the maxillary first molars, the type of movement, the difference between actual and predicted amounts of distalization, and the relationship between the amount of distalization and age.

METHODS

Twenty-five nongrowing patients (22 female, 3 male) successfully treated with the SAS were the subjects in this study. The amount and the type of distalization, the difference between predicted and resulting amounts of distalization, and the relationship between the patient's age and the amount of distalization were analyzed with wide-opening cephalometric radiographs.

RESULTS

The average amount of distalization of the maxillary first molars was 3.78 mm at the crown level and 3.20 mm at the root level. The amount of distalization at the crown level was significantly correlated with the average value of treatment goals (3.60 mm).

CONCLUSIONS

The maxillary molars were predictably distalized in accordance with the individualized treatment goals without regard to patient age and extraction of the third or second molars. The SAS is a viable noncompliance modality to move maxillary molars for distally correcting maxillary protrusions and malocclusions characterized by maxillary incisor crowding.

Effect of cervical headgear wear on dynamic measurement of head position

The aim of this study was to identify the effect of cervical headgear (CHG) wear on dynamic measurement of head posture during walking. Six male and 10 female patients (mean age, 11.9 +/- 1.9 years) who were receiving CHG therapy for correction of a Class II molar relationship as part of their orthodontic treatment were included in this study. Dynamic head posture measurements were recorded using an inclinometer and data logger apparatus during a walking session of 5 minutes. This procedure was repeated before (T1) and after (T2) insertion of CHG. The T1 and T2 measurements were repeated twice at 30-minute intervals. The mean dynamic head posture was calculated for each subject using the collected data. The means of these measurements were statistically compared using a paired t-test. Of the 16 subjects, 14 showed a cranial flexion with CHG wear in relation to T1 (1.4 to 8.9 degrees). The other two subjects showed a cranial extension of -1.6 and -3.8 degrees. The mean values at T1, T2 and T1-T2 were 1.4, -1.8, and 3.1 degrees, respectively, which indicated a mean cranial flexion at T2 in relation to T1. According to the paired sample t-test, there were statistically significant differences between the two measurements of dynamic head posture recorded before and after CHG insertion (P < 0.001). CHG wear causes a significant cranial flexion which may be responsible for its effects on the mandible.

The effects of early headgear treatment on dental arches and craniofacial morphology: an 8 year report of a randomized study

The aim of this study was to determine the long-term effects of early headgear (HG) treatment on craniofacial structures. The total study group comprised 68 children (40 males and 28 females) aged 7.6 years (standard deviation 0.3 years). The children, who had a Class II tendency in occlusion and moderate crowding, were randomly divided into two groups of equal size. In the first group, HG treatment was initiated immediately. In the second group, which served as a control group, only minor interceptive procedures were performed during the first follow-up period of 2 years. During the 8 year follow-up, orthodontic therapy, including fixed appliances and possible extractions, was carried out when necessary. The results showed that the most evident difference between the groups was the wider and longer dental arches in the HG group, which could only partly be explained by the higher rate of extractions in the control group. For the cephalometric measurements, the most significant difference was in the maxillary plane orientation. The peer assessment rating (PAR) score, showing the general outcome of treatment, was at the same level in both groups at follow-up. The deficit of the early HG treatment was the longer mean total treatment time, resulting from the two-phase treatment.

Effectiveness of early treatment of Class II malocclusion

The purpose of this study was to examine and report the effectiveness of early treatment with the headgear/biteplate and the bionator in patients with Class II malocclusion regardless of the mechanism of correction and to compare early-treatment results with changes over a similar time period in an observation group. The role of factors such as compliance was examined to determine their contribution to effective treatment. The experimental design was a prospective, longitudinal, randomized controlled trial. At the end of the early-treatment period, all 3 groups differed significantly (overall, P = .001) in percentage of treatment goal achieved, with median values of 83% for the bionator group, 100% for the headgear group, and 14% for the observation group. In both treated and observation subjects, the percentages of goal achieved varied by initial molar class severity (treated, P =.0205; observation, P = .0040) and race (treated, P = .0314; observation, P = .0416). Significant correlations in the treated subjects were identified between percentage of goal achieved and bone age (13 bones) (r = 0.16; P = .037), bone age (20 bones) (r = 0.16; P = .043), compliance (r = 0.26; P = .0005), and initial overjet (r = -0.26; P = .0095). Significant correlations were not detected in the observation group. Sex, treatment group, age, mandibular plane angle, pretreatment, and retention did not significantly affect percentage of goal achieved among the treated and the observation subjects. Correlation between normalized compliance scores and percentage of goal achieved was high for both bionator (r = 0.50) and headgear subjects (r = 0.49) at the end of treatment. Multivariate analysis suggested that headgear may be superior to bionator/biteplane in achieving a Class II correction during early treatment.

Changes in mandibular position and upper airway dimension by wearing cervical headgear during sleep

We previously reported that the wearing of cervical headgear induced forward displacement of the mandible in awake subjects. However, it was unclear whether such mandibular displacement also occurred during sleep. The purpose of this study was to examine changes in mandibular position and oropharyngeal structures that were induced by the wearing of cervical headgear during sleep. Ten healthy adults (7 male and 3 female) who gave their informed consent were included in this study. A pair of lateral cephalograms was taken with the patient in the supine position with and without cervical headgear at end-expiration during stage 1 to 2 non-rapid-eye-movement sleep. The Wilcoxon signed-rank test was used for a statistical analysis. The amount of jaw opening was significantly decreased by the wearing of the cervical headgear (P <.05), although no significant anteroposterior mandibular displacement was induced. The sagittal dimension of the upper airway was significantly reduced (P <.05); however, no significant changes were observed in the vertical length of the upper airway. Although the hyoid bone and the third cervical vertebra moved significantly forward by the wearing of the cervical headgear (P <.05), the relationship among the mandibular symphysis, the hyoid bone, and the third cervical vertebra did not change. These results suggest that cervical headgear significantly reduced the sagittal dimension of the upper airway during sleep, although there was no significant anteroposterior displacement of the mandible.

Sagittal and vertical changes after treatment of Class II Division 1 malocclusion according to the Cetlin method

This cephalometric study was designed to evaluate the dentoskeletal anteroposterior and vertical changes produced by Cetlin therapy (lower lip bumper, ACCO, cervical headgear) to correct Class II Division 1 malocclusion in the late mixed dentition. All measurements were made on 2 lateral headfilms, at pretreatment and at 1 year after beginning treatment. The selected sample (n = 110; 67 boys and 43 girls; mean age, 10 to 11 years) and the control group (n = 100; 48 boys, 52 girls; mean age, 10 to 11 years) matched for number, age, and malocclusion. The average observation interval was 13 months. The final measurements between intervals were averaged and tested for significance by analysis of variance. A one-factor (group) repeated measure model and a two-factor (group and facial type) repeated measure model were fitted to each variable separately and significance values were set at P </=.05. The Class I molar relationship was achieved in all treated subjects primarily through distalization of upper first molars. A significant distal tipping was found in 70% of the treated cases. The results showed a significant forward growth limitation of the maxilla with the use of cervical headgear. No significant change of mandibular position was found in the treated group compared with the control group. Both bite opening and proclination of upper and lower front teeth occurred. Cetlin therapy is reliable and effective for space recovery and interceptive Class II Division 1 treatment. Additional therapy may be needed later.

Comparison of Jones jig molar distalization appliance with extraoral traction

In this study, 20 patients were evaluated. Ten were treated with intraoral distalization followed by fixed appliance therapy, and 10 were treated with extra oral traction followed by fixed appliance therapy. Molar relationship correction was achieved in 2.5 months with intraoral distalization and in 10.7 months with extraoral distalization. A significant anterior movement of the anchorage unit (P <.001) was observed with the intraoral distalization and a significant distal drift of premolars was observed in the headgear group (P <.05). Palatal plane was found to tip downward significantly in the headgear group (P <.05). Total outcome of the 2 methods were discussed evaluating the advantages and disadvantages of the 2 distalization methods.

Effects of different vectors of forces applied by combined headgear

The effects of various directed forces applied by combined headgear were evaluated in this study. The study material consisted of 30 patients with Class II dental relationships and steep mandibular plane angles. Three groups of 10 patients each were formed. In the first treatment group, forces of 150 gm per side were used for the high-pull component and the cervical component. In the second treatment group, forces of 200 gm per side for the high-pull component and 100 gm per side for the cervical component were applied. In the third treatment group, forces of 100 gm per side were applied for the high-pull component and 200 gm per side for the cervical component. Distal tipping of upper molar was greatest in the third treatment group. Intrusion of the upper molar in the second treatment group and extrusion of the upper molar in the third treatment group were statistically significant. Changes in occlusal and mandibular plane angles showed significant differences between the groups.

Long-term stability of Angle Class II, division 1 malocclusions with successful occlusal results at end of active treatment

The purpose of this study was to examine long-term stability of Angle Class II, Division 1 malocclusions with successful occlusal results at the end of active appliance therapy, search for predictors of relapse, and look for characteristics associated with successful treatment. Records taken before and after treatment and a mean of 14.0 years postretention of adolescent patients treated for a significant Angle Class II, Division 1 malocclusion both with and without tooth extraction were evaluated. The sample was limited to successfully treated cases as judged by subjective evaluation of intercuspation and incisor occlusion of posttreatment study models and included 78 patients. Cephalometric characteristics or postretention occlusion was not considered in sample selection. The mode response was no change postretention for molar, premolar, and canine relationships and relapse of 0.5 mm for overjet and overbite. Maximum relapse was 3.5 mm for molar, premolar, and canine relationship, 3 mm for overjet, and 4.5 mm for overbite. Stepwise backward multiple regression analyses revealed no associations between either pretreatment characteristics or skeletal and dental treatment changes and relapse of overjet. However, relapse of overjet was associated with relapse of molar, premolar, and canine relationships, postretention increase in overbite, postretention proclination of maxillary incisors, and postretention retroclination of mandibular incisors. Active treatment changes included redirection or inhibition of maxillary growth and retraction of maxillary incisors. Mandibular incremental growth was favorable both during and after treatment. It was concluded that successful correction of Angle Class II, Division 1 malocclusions through differential growth adaptation and tooth movement appears to be very stable.

A tensor analysis to evaluate the effect of high-pull headgear on Class II malocclusions

The inaccuracies inherent in cephalometric analysis of treatment effects are well known. The objective of this article is to present a more reliable research tool in the analysis of cephalometric data. Bookstein introduced a dilation function by means of a homogeneous deformation tensor as a method of describing changes in cephalometric data. His article gave an analytic description of the deformation tensor that permits the rapid and highly accurate calculation of it on a desktop computer. The first part of this article describes the underlying ideas and mathematics. The second part uses the tensor analysis to analyze the cephalometric results of a group of patients treated with high-pull activator (HPA) to demonstrate the application of this research tool. Eight patients with Class II skeletal open bite malocclusions in the mixed dentition were treated with HPA. A control sample consisting of eight untreated children with Class II who were obtained from The Ohio State University Growth Study was used as a comparison group. Lateral cephalograms taken before and at the completion of treatment were traced, digitized, and analyzed with the conventional method and tensor analysis. The results showed that HPA had little or no effect on maxillary skeletal structures. However, reduction in growth rate was found with the skeletal triangle S-N-A, indicating a posterior tipping and torquing of the maxillary incisors. The treatment also induced additional deformation on the mandible in a downward and slightly forward direction. Together with the results from the conventional cephalometric analysis, HPA seemed to provide the vertical and rotational control of the maxilla during orthopedic Class II treatment by inhibiting the downward and forward eruptive path of the upper posterior teeth. The newly designed computer software permits rapid analysis of cephalometric data with the tensor analysis on a desktop computer. This tool may be useful in analyzing growth changes for research data.

Vertical changes in high-angle Class II, division 1 patients treated with cervical or occipital pull headgear

Before, after, and 2 years after treatment serial radiographs of two samples of patients with high mandibular plane angle Class II, Division 1 nonextraction who were treated were evaluated retrospectively. One sample comprised patients treated with cervical headgear (CHG), and the other was treated with occipital headgear (OPHG). No significant differences were found when mandibular plane angle or facial height changes, anterior or posterior, were compared. Regarding vertical changes, only maxillary molar height, relative to both sella-nasion and palatal plane, and occlusal plane angle changes were significantly different when cervical and occipital-pull headgear were compared. In both groups of patients, responses to treatment were highly variable and only subtle vertical differences were apparent between mean changes in the cervical and occipital-pull samples.

Dental and orthopedic effects of high-pull headgear in treatment of Class II, division 1 malocclusion

In the present study a prospective cephalometric investigation was undertaken to examine the skeletal and dental effects of the high-pull extraoral appliance, when the resultant force was directed through the level of trifurcation of the maxillary molars. Twelve adolescent patients with Class II, Division 1 malocclusions were selected for the study. Each patient wore the headgear for a 6-month period, an average of 12 hours a day. A group of untreated adolescent patients with Class II, Division 1 malocclusions who were in a similar age range, as well as skeletal and dental characteristics were chosen as controls. Lateral cephalometric films were taken before and after the 6-month treatment period, and before and after the observation period in the control group of patients. Our data indicate that by directing the force of the headgear approximately through the center of resistance of the maxillary molars, it is possible to accomplish simultaneously a substantial distal movement of the molars (2.6 +/- 0.6 mm), as well as significant intrusion (0.54 +/- 0.54 mm). In addition, our results demonstrate that the applied force of 500 gm was sufficient to initiate maxillary orthopedic changes in the treated patients. These changes include relative restriction of horizontal and vertical maxillary growth, as well as distal movement (mean: 0.8 mm) of the maxillary anterior border in the treatment group relative to an untreated control group. Such orthopedic changes have been previously described only in association with much higher force levels.

The effects of extraction and nonextraction treatment on the mandibular position

Decisions on extraction of teeth as an aid in orthodontic treatment depend on dental and skeletal discrepancies concerning sagittal and vertical relationships. The purpose of this study was to assess the effects of extraction and nonextraction procedures on the posterior rotation of the mandible and the position of gnathion. Forty-eight nonextraction patients and seventy-three extraction patients treated in the orthodontic department were selected. The patients were from 11 to 15 years old, with a mean age of 12 years 2 months. The lateral cephalometric radiographs taken before and after treatment were traced and measured. Eleven variables reflecting the mandibular rotation were selected on the basis of factor analysis. Before treatment, total arch circumferential discrepancy and the 11 selected measurements showed significant differences between the extraction and nonextraction groups. In the extraction group, the lower anterior facial height was larger, ramus height was smaller, and the difference between vertical position of both maxillary and mandibular first molars and posterior facial height was greater than in the nonextraction group. Consequently, the mandible showed posterior rotation and was in retruded position in the extraction group. In the nonextraction group, the type of force application had no significant effect on the changes in skeletal and dental measurements. In the extraction group, however, the type of force application had a significant effect (p less than 0.05) on the changes in total anterior facial height, the horizontal distance of the maxillary first molar to a perpendicular line to the S-N plane passing through point S, the vertical distance of the maxillary molar to the S-N plane, the vertical distance of the maxillary and mandibular first molars to the S-N plane, the difference between the vertical position of the first molars and posterior facial height, and the difference between the vertical position of the first molar and vertical height of the ramus. In the group in which high-pull face-bow headgear was used, the extraction/nonextraction procedures had a significant effect (p less than 0.05) on the changes in angle ANB, total anterior facial height, anterior lower facial height, and the difference between anterior and posterior facial height.(ABSTRACT TRUNCATED AT 400 WORDS)

Dental and skeletal contributions to occlusal correction in patients treated with the high-pull headgear-activator combination

The purpose of this study was to examine dental and skeletal changes in patients treated with the high-pull headgear-activator combination. A group of 40 consecutively treated subjects with a Class II molar relationship and a minimum of 5 mm overjet was used for this study. The results showed that Class II correction often was achieved by distal repositioning of the maxillary teeth (mean, 0.07 mm) and mesial repositioning of the mandibular teeth (mean, 3.3 mm) with a wide range of variation. Correlation of maxillary molar repositioning with total interarch occlusal change showed a positive relationship; however, a weak correlation suggested that other variables were contributing factors, in addition to distal upper molar positioning. The change in mandibular molar position compared with the movement of pogonion strongly suggests that forward growth of the mandible is important to the correction of the Class II malocclusion. When total molar repositioning in the upper jaw was correlated with total molar repositioning in the lower jaw, a strong inverse correlation was found, indicating that upper molar movement parallels lower molar movement.

A cephalometric study to compare the effects of cervical traction and Andresen therapy in the treatment of class II division 1 malocclusion. Part 2--Dentoalveolar changes

Absolute distal movement of upper first molars together with distal tipping, but no significant extrusion, occurred with cervical traction. Distal movement of the maxillary first molars was more stable in the group where maxillary 2nd molars had been extracted. With Andresen treatment a restraining effect took place on the upper molars, while mesial movement of the lower first molars contributed to correction of the molar relationship.

A cephalometric study to compare the effects of cervical traction and Andresen therapy in the treatment of Class II division 1 malocclusion. Part 1--Skeletal changes

Lateral cephalometric radiographs at the beginning of treatment, end of active treatment, and post-treatment of 30 Andresen and 40 cervical traction patients were analysed, and compared with those of a control group of 22 untreated cases. The cervical traction group was divided into a non-extraction group and an extraction of maxillary second molars group. A clinically significant reduction of ANB was achieved, mainly by mandibular changes in the Andresen group and by maxillary changes in the cervical traction groups. Cervical traction was associated with a small distal positioning and anterior downward tipping of the maxilla during treatment. A more favourable sagittal position of the mandible was achieved in the Andresen group compared to the cervical traction groups, particularly the non-extraction group, where a greater transient backward rotation of the mandible occurred during treatment. A significant, but clinically small increase in mandibular body length occurred in Andresen patients compared to the control. However, in both treatment groups this was due to an increase in growth of the vertical ramus. The lower face heights, both anterior and posterior, increased in all groups, with the anterior upper face height also increasing in the cervical traction group.

Three-dimensional model of the human craniofacial skeleton: method and preliminary results using finite element analysis

The purpose of this study was to develop a three-dimensional finite element model of the craniofacial skeleton using a dry human skull. The model consisted of 2918 nodes and 1776 solid elements, and was used to investigate the biomechanical effect of a distally directed orthopaedic force on the craniofacial complex. The force was applied at the level of the maxillary first molar. The results indicated that in response to the force system applied: the nasomaxillary complex displaces in a backward and downward direction and rotates in clockwise sense; the nasomaxillary complex, including the zygomatic bone, experiences high stress levels in comparison with those at the remaining bones; the stress distribution in the maxillary basal bone area is relatively uniform; and the stress distribution across the opposing surface of the bony margins of the sutures is non-uniform.

A cephalometric appraisal of edgewise Class II nonextraction treatment with extraoral force

The purpose of this study was to determine the treatment effects of nonextraction edgewise therapy combined with cervical headgear on Class II, Division 1 malocclusions. Data from a sample of 43 treated patients with a mean age of 11 years 11 months and a mean treatment time of 2 years 8 months were recorded. A cephalometric appraisal was done and the initial and final measurements of points, lines, and angles based on accepted cephalometric analyses were compared. Student's t test for paired cases was used to evaluate the significance of all measurement changes. The significant findings were as follows: the inhibition of forward growth of the maxilla, downward tipping of the anterior part of the palate, reduction of flaring of the maxillary incisors, reduction of the facial convexity, and extrusion and mesial movement of maxillary and mandibular first molars. The overall results tend to indicate the efficacy of this treatment modality in the treatment of the Class II, Division 1 malocclusion.

The effects of three methods of orthodontic appliance therapy on some commonly used cephalometric angular variables

This investigation was undertaken to study the effects of the Andresen activator functional appliance therapy, Begg therapy, and cervically directed extraoral forces upon several commonly used cephalometric angular variables, with particular reference to the relationship between the maxillary plane (palatal plane) and anterior cranial base as represented by SN line. The material consisted of 107 cases taken from the files of patients who had attended the Orthodontic Department, Eastman Dental Hospital, London. Ninety of the cases had received orthodontic treatment. For each case pretreatment, posttreatment, and postretention radiographs were traced and angular measurements made by means of a Lysta-Dent digitizer linked to an on-line computer. Descriptive statistics and one-sample and two-sample Student's t tests were performed. None of the treatment methods under investigation had a clinically significant effect upon the maxillary plane. An increase in the inclination of the mandibular plane was a feature of Begg and headgear therapies but not of Andresen therapy. Any increase observed was of a temporary nature. While no change in SNA occurred with Andresen therapy, Begg and headgear therapies produced a permanent reduction in the variable. A small reduction was also produced in SNB by Begg and headgear therapies. The behavior of SNB following Andresen therapy was not significantly different from that in the group of untreated subjects. Each appliance method produced a permanent reduction in ANB; however, a similar reduction was also demonstrated in the control group.