Theoretical considerations of headgear therapy: a literature review. 1. Mechanical principles

Long-term stability after high-pull headgear combined with fixed appliances: A retrospective cohort study of growing class II patients

BACKGROUND

High-pull headgear with fixed appliances is a common therapeutic plan in class II growing individuals, especially in those with a tendency to hyperdivergence. The stability of this approach has not been adequately assessed in the long-term. The aim of this retrospective study was to assess that long-term stability by means of lateral cephalograms. Seventy-four consecutive patients were included and examined at three time-points: pre-treatment (T1), end of treatment (T2), and at least five years post-treatment (T3).

RESULTS

The average initial age of the sample was 9.3 years (standard deviation, SD: 1.6). At T1, the mean ANB was 5.1 degrees (SD: 1.6), the mean SN-PP 5.6 (SD: 3.0) and the mean MP-PP 28.7 degrees (SD: 4.0). The median follow-up time was 8.6 years with an interquartile range of 2.7. A statistically significant, but of small magnitude increase in the SNA angle was noted at T3 compared to T2 after adjusting for the pre-treatment SNA value (mean difference (MD): 0.75; 95% CI: 0.34, 1.15; P<0.001). The inclination of the palatal plane appeared stable in the post-treatment period, while the MP-PP angle showed scarce evidence of decrease during the post-treatment period after adjusting for sex, pre-treatment SNA and SN-PP angles (MD: -2.29; 95% CI: -2.85, -1.74; P<0.001).

CONCLUSIONS

The sagittal position of the maxilla and the inclination of the palatal plane appeared to be stable after treatment with high-pull headgear and fixed appliances in the long-term. Continuous mandibular growth, both sagittaly and vertically, contributed to the stability of class II correction.

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.

The impact of force magnitude on the first and second maxillary molars in cervical headgear therapy

AIM

To study the effect of force magnitude on the maxillary first and second molars in cervical headgear (CHG) therapy.

MATERIAL AND METHODS

In this controlled clinical trial, patients (n = 40) were treated with CHG with a light (L, 300 g, n = 22) or a heavy force (H, 500 g, n = 18) magnitude. The subjects were asked to wear CHG for 10 hours a day for 10 months. The outer bow of the CHG facebow was lifted up for 10-20 degrees and the inner bow was expanded 3-4 mm. Adherence to instructions and force magnitude were monitored using an electronic module (Smartgear, Swissorthodontics, Switzerland). Panoramic and lateral radiographs before (T1) and after treatment (T2) were analysed using a Romexis Cephalometric module (Planmeca, Finland) focussing on the angular, sagittal, and vertical positions of the permanent first and second molars.

RESULTS

According to the cephalometric analysis of the maxillary first and second molars, distal tipping occurred during T1-T2 in the H group (P = 0.010 and 0.000, respectively), and the change was greater in the H group compared to the L group (P = 0.045 and 0.019, respectively). Based on the panoramic analysis, tipping occurred in the distal direction during therapy in the H group in the second molars compared to the midline or condylar line (P = 0.001 and 0.001; P = 0.008 and 0.003 on the right and left, respectively).

CONCLUSION

With heavy force magnitude, the maxillary first and second molars can tilt more easily in the distal direction even if the CHG was used less. Distal tipping of the molar can be considered to be a side effect of CHG therapy.

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.

Class II malocclusion treatment using high-pull headgear with a splint: a systematic review

OBJECTIVE: To systematically review the scientific evidence pertaining to the effectiveness of high-pull headgear in growing Class II subjects. METHODS: A literature survey was performed by electronic database search. The survey covered the period from January 1966 to December 2008 and used Medical Subject Headings (MeSH). Articles were initially selected based on their titles and abstracts; the full articles were then retrieved. The inclusion criteria included growing subjects between 8 to 15 years of age, Class II malocclusion treatment with high-pull headgear, and a control group with Class II malocclusion. References from selected articles were hand-searched for additional publications. Selected studies were evaluated methodologically. RESULTS: Four articles were selected; none were randomized controlled trials. All of the articles clearly formulated their objectives and used appropriate measures. The studies showed that high-pull headgear treatment improves skeletal and dental relationship, distal displacement of the maxilla, vertical eruption control and upper molars distalization. One of the studies showed a slight clockwise rotation of the palatal plane; the others showed no significant treatment effect. The mandible was not affected by the treatment. CONCLUSION: While there is still a lack of strong evidence demonstrating the effects of high-pull headgear with a splint, other studies indicate that the AP relations improve due to distalization of the maxilla and upper molars, with little or no treatment effects in the mandible. Greater attention to the design should be given to improve the quality of such trials.

Impact of orthodontic appliances on sleep quality

INTRODUCTION

Many young patients are asked to wear headgear or functional appliances during sleep as part of their orthodontic treatment. The objective of this clinical study was to assess the impact of these appliances on sleep quality.

METHODS

Twenty-two subjects (8 boys, 14 girls) between 10 and 15 years of age wearing either a headgear or a removable appliance for 3 to 12 months were enrolled in a sleep study. Each subject participated in 2 overnight sleep studies with and without the appliance. There was a 1-week interval after an adaptation night. The studies were performed at the Sleep Research Laboratory at Toronto Western Hospital in Canada. Each subject served as his or her own control. Twelve subjects had an extraoral headgear appliance, and 10 had intraoral functional (5 Fränkel, 5 Twin-block) appliances. No subject reported any sleep or medical disorder. The primary outcome variable was sleep efficiency.

RESULTS

Sleep efficiencies were 90.7% (SD, 7.9) and 91.6% (SD, 4.3) with and without the appliances, respectively. When sleep quality was compared with and without appliances, analysis of variance (ANOVA) showed no significant difference in sleep efficiency or other sleep variables such as sleep onset latency, rapid eye movement onset latency, rapid eye movement percentage, short-wave sleep percentage, or respiratory disturbance index. Sex and body mass index were not confounding variables. In addition, the use of extraoral or intraoral appliances did not affect sleep quality.

CONCLUSIONS

In young orthodontic patients, there appears to be no difference in sleep quality with or without the overnight use of these appliances after they have been worn for a minimum of 3 months.

Clinical and quantitative assessment of headgear compliance: A pilot study

INTRODUCTION

This study was undertaken to evaluate the compliance of patients using headgear with a timing device and to determine the efficiency of the electronic module timer as a patient motivator.

METHODS

Twenty-one patients (average age, 14 years 10 months) were selected from the orthodontic clinic of Federal University of Paraná on the basis of headgear wear for anchorage. The patients were instructed to wear their headgear 14 hours a day for a given number of days. The headgears were equipped with recorders (Compliance Science System and Affirm smart headgear modules, Ortho Kinetics, Vista, Calif). The patients were not told about the recorders, but they were instructed to keep track of their wear times. At the end of the test period (T1), the patients' reported wear times were compared with readings from the electronic modules. The patients were assigned a second period of headgear wear (T2) and told that their use would be monitored electronically. Again, the wear times reported by the patients were compared with the values from the electronic modules. Total time, number of hours accumulated between sessions, and quality time (uninterrupted use of headgear) were assessed.

RESULTS

Patients reported wearing their headgear an average of 13.6 hours per day; the electronic modules detected 5.6 hours per day in T1 and 6.7 hours per day in T2. Quality time was 1.8 hours per day in T1 and T2. The mean actual hours of daily wear relative to the provider's requirement was 56.7% in T1 and 62.7% in T2. Boys were more compliant than girls. After they learned of the electronic device, the girls' compliance improved. Younger patients were more compliant than older ones. The compliance rate of older patients improved slightly in T2.

CONCLUSIONS

Patients tend to overreport their headgear wear times. The mean actual hours of daily wear relative to the providers' requirement was 56.7%. This increased to 62.7% when patients knew a recording device was being used. A monitoring system can provide feedback to the patient, facilitate parental involvement, and motivate patients to comply with headgear wear.

Evaluation of Class II treatment by cephalometric regional superpositions versus conventional measurements

INTRODUCTION

The aims of this study were (1) to evaluate cephalometric changes in subjects with Class II Division 1 malocclusion who were treated with headgear (HG) or Fränkel function regulator (FR) and (2) to compare findings from regional superpositions of cephalometric structures with those from conventional cephalometric measurements.

METHODS

Cephalographs were taken at baseline, after 1 year, and after 2 years of 65 children enrolled in a prospective randomized clinical trial. The spatial location of the landmarks derived from regional superpositions was evaluated in a coordinate system oriented on natural head position. The superpositions included the best anatomic fit of the anterior cranial base, maxillary base, and mandibular structures.

RESULTS

Both the HG and the FR were effective in correcting the distoclusion, and they generated enhanced differential growth between the jaws. Differences between cranial and maxillary superpositions regarding mandibular displacement (Point B, pogonion, gnathion, menton) were noted: the HG had a more horizontal vector on maxillary superposition that was also greater (.0001 < P < .05) than the horizontal displacement observed with the FR. This discrepancy appeared to be related to (1) the clockwise (backward) rotation of the palatal and mandibular planes observed with the HG; the palatal plane's rotation, which was transferred through the occlusion to the mandibular plane, was factored out on maxillary superposition; and (2) the interaction between the inclination of the maxillary incisors and the forward movement of the mandible during growth.

CONCLUSIONS

Findings from superpositions agreed with conventional angular and linear measurements regarding the basic conclusions for the primary effects of HG and FR. However, the results suggest that inferences of mandibular displacement are more reliable from maxillary than cranial superposition when evaluating occlusal changes during treatment.

An unreported risk in the use of home nasal continuous positive airway pressure and home nasal ventilation in children: mid-face hypoplasia

We report the case of a 15-year-old boy with obstructive sleep apnea and obesity who was treated since the age of 5 with nasal continuous positive airway pressure. Due to the long-term use of a nasal mask, the child developed a mid-face hypoplasia. Chronic use of a nasal mask for home ventilation in children should always be associated with regular evaluations of maxillomandibular growth.

Headgear versus function regulator in the early treatment of Class II, division 1 malocclusion: a randomized clinical trial

A prospective randomized clinical trial was conducted to evaluate the early treatment of Class II, Division 1 malocclusion in prepubertal children. Facial and occlusal changes after treatment with either a headgear or a Fränkel function regulator are reported. Molar and canine relationships, overjet, intermolar and intercanine distances were measured from casts taken every 2 months, and mounted on a SAM II articulator. Cephalometric radiographs were taken annually. The results indicate that both the headgear and function regulator were effective in correcting the malocclusion. A common mode of action of these appliances is the possibility to generate differential growth between the jaws. The extent and nature of this effect, as well as other skeletal and occlusal responses differ. Treatment in late childhood was as effective as that in midchildhood. This finding suggests that timing of treatment in developing malocclusions may be optimal in the late mixed dentition, thus avoiding a retention phase before a later stage of orthodontic treatment with fixed appliances. However, a number of conditions may dictate an earlier intervention in the individual patient.

Changes in dental arch dimensions by use of an orthopedic cervical headgear in Class II correction

Orthopedic cervical headgears are commonly used in Finland for early treatment of the Class II malocclusion, but there is a lack of follow-up studies on the effect of this treatment. We have evaluated the effects of the cervical headgear therapy with an expanded inner bow to treat Class II malocclusion and dental arches. Forty children, 20 boys and 20 girls, with Class II, Division 1 malocclusion, were treated with the orthopedic cervical headgear. No other appliances were used. The mean age of the subjects in the beginning of the treatment was 9.3 +/- 1.3 years (range 6.6 to 12.4 years). The mean treatment time was 1.8 +/- 0.6 years (range 0.8 to 3.1 years). The cervical headgear was used with a 10 mm expanded inner bow and a 15 degrees upward bend of the long outer bow, 12 to 14 hours a day with a force of 500 gm per side. Class I relationships were achieved in all subjects. At the same time, the maxillary and mandibular dental arches were widened. The annual increment in the intercanine and intermolar distances was significantly greater than in healthy control subjects (literature data), except for the mandibular intercanine distance in boys. The maxillary arch lengths were also significantly increased; there were no consistent changes of the mandibular arch lengths. Class II malocclusion may be treated with the orthopedic cervical headgear. The treatment results in increased growth of the dental arch widths by expansion of the inner bow of the headgear. The widening of the maxilla is followed by spontaneous widening of the mandible.

Changes of arch width in the early treatment of Class II, division 1 malocclusions

Changes in arch width during the early correction of Class II, Division 1 malocclusions with either the Fränkel functional appliance or headgear are compared in an ongoing prospective randomized clinical trial. The data were collected from 43 children, ages 7.5 to 12.85 years, who met strict dental and cephalometric criteria for inclusion in the study. They were assigned at random to treatment with either a headgear (n = 21) or a Fränkel appliance (n = 22). Occlusal measurements included the maxillary and mandibular intermolar distances (buccal and palatal/lingual) and intercanine distances. Measurements (millimeters) were performed on casts taken every 2 months, with digital calipers accurate to 0.01 mm. Four months after the initiation of treatment, the mean maxillary intermolar distance was larger in the Fränkel group (palatal: 1.58, SE: 0.22; buccal: 1.58, SE: 0.20) than the headgear group (palatal: -0.39, SE: 0.21; buccal: 0.26, SE: 0.23), and the difference was statistically significant (palatal: p < 0.0001 and buccal: p = 0.0001). The mean maxillary intercanine distance increased more with the headgear (1.62, SE: 0.19) than the Fränkel appliance (0.62, SE: 0.23) p = 0.003. As treatment progressed, the average intermolar distance in the headgear group increased, but was still higher in the Fränkel group by more than 1 mm. The intercanine distance remained larger in the headgear group. The mandibular intermolar and intercanine distances were higher after Fränkel therapy than with headgear.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Canine retraction with the edgewise appliance-some problems and solutions

The three basic methods of canine retraction discussed all have their inherent advantages and disadvantages and all can cause problems. The retraction systems which slide canines along a relatively rigid archwire, would appear to have the advantage of achieving better controlled apical and crown movement but at the obvious cost of greater friction and binding than the sectional arch. Of course the direct headgear system to some extent avoids the consequences to the anchorage, but there again the force to the canine is only intermittent and movement consequently is slower than if elastic traction were applied. If sliding mechanics are used either with a J hook headgear to canines or elastic intra-traction from the molars, it would seem advisable to use a heavy round wire in at least a medium width bracket. To help decrease binding when using elastic traction, power arms would certainly seem to have a place, with the added benefit of patients having an accessible hook to change elastics themselves. If sectional arches are used it is advisable to use a heavy rectangular wire to maintain as much control as possible. Due to the compromise between horizontal flexibility and vertical rigidity already discussed, it is very easy to over-activate a sectional arch with its inevitable consequence of excessively tipping the canine and/or losing molar anchorage.

Retraction of canines with axial control using extra-oral traction

Retraction of canines with control of tooth inclination is described, using the direct application of extra-oral traction. the technique requires a modified facebow to be inserted into buccal tubes on canine bands; no archwires or springs are involved. In the upper arch the facebow is connected to a standard variable pull headgear, while a supported cervical strap is required for the lower canines. Preliminary investigations are outlined and the procedure is illustrated by some clinical cases from a pilot feasibility study.

Theoretical considerations of headgear therapy: a literature review. 2. Clinical response and usage

In Part 1 the literature on the direction and moment force systems of headgear therapy was discussed. The magnitude and duration of forces were briefly dealt with. In Part 2 the clinical response to the main directions of headgear force as reported in the literature will be described. Recommendations on the most appropriate direction and moment force systems for particular clinical situations will be made.