Distal movement of buccal segments with the "en masse" removable appliance--its value in treating patients with mild Class II, Division 1 malocclusions: Part I, clinical techniques (how to do it)

Combined treatment with headgear and the Frog appliance for maxillary molar distalization: a randomized controlled trial

Objective

To evaluate the efficiency of the Frog appliance (FA) alone or in combination with headgear for distalizing the maxillary molars.

Methods

Fifty patients (25 males and 25 females) aged 12.6 - 16.7 years who received treatment for Class II malocclusion at the Orthodontic Clinic of Al-Baath University were selected for this study and randomly divided into 2 equal groups. Maxillary molar distalization was achieved using the FA alone (group 1) or a combination of the FA with high-pull headgear worn at night (group 2). Lateral cephalograms were obtained before and after treatment.

Results

The maxillary molars moved distally by 5.51 and 5.93 mm in groups 1 and 2, respectively. Distal movements were associated with axial tipping by 4.96° and 1.25°, and with loss of anchorage by mesial movement of the second maxillary premolars by 2.70 and 0.90 mm in groups 1 and 2, respectively. The combined use of the FA and nighttime high-pull headgear decreased the distalization time and improved the ratio of maxillary molar distalization movement relative to the overall opening space between the first maxillary molars and second premolars.

Conclusions

The FA can effectively distalize the maxillary molars, this distalization associates with some unfavorable changes. Nighttime use of high-pull headgear combined with the FA can reduce these unfavorable changes and improve treatment outcomes.

Comparison of arch dimension changes in 1-phase vs 2-phase treatment of Class II malocclusion

INTRODUCTION

We compared arch dimension changes in 1-phase and 2-phase treatment of Class II malocclusion. This was a prospective randomized clinical trial conducted in the Department of Orthodontics at the University of Florida between 1990 and 2003.

METHODS

During phase 1 treatment, 86 subjects were treated with a bionator, 93 were treated with headgear/biteplane, and 81 served as the observation group. For phase 2, all subjects were then treated with full orthodontic appliances. Arch dimensions were followed; maxillary and mandibular alginate impressions were taken at baseline, end of early Class II treatment or observation, beginning of fixed appliance treatment, end of orthodontic treatment, and approximately 3 years posttreatment. Alginate impressions were taken of each dental arch at each data collection point. These were poured in orthodontic stone, trimmed, and photocopied from the occlusal aspect. These images were then scanned and measured.

RESULTS

Although differences between the treatment groups were found in both the maxillary and mandibular arches after phase 1, these differences were no longer evident by the end of full orthodontic treatment or after posttreatment retention.

CONCLUSIONS

There were no differences in arch dimensions after 1-phase or 2-phase treatment of Class II malocclusion.

Eruption of third permanent molars after the extraction of second permanent molars. Part 1: Assessment of third molar position and size

The eruptive path of third molars after extraction of second molars was examined in 63 patients. Panoramic radiographs from the start and the end of active treatment and 3 or more years after treatment were assessed. Study models were used to compare the size of the second and third molars and to assess the final position of the third molars. All third molars erupted; none became impacted. During eruption, maxillary third molar crowns uprighted and maintained their angulation as they came into occlusion. Mandibular third molar crowns continued to upright significantly mesiodistally after active treatment, with space closure the result of horizontal translation rather than mesial tipping. Further uprighting occurred once occlusion was established, although few became as upright as the second molars they replaced. However, mandibular third molar roots were frequently curved distally, thus the third molar crown position was invariably better than the overall tooth angulation would suggest, by 16.5 degrees on average. Model analysis (Richardsons' scoring system) showed 96% of mandibular and 99% of maxillary third molars erupted into a good or acceptable position. Limitations of this scoring system are discussed. The mesiodistal size of third molars was suitable to replace second molars; on average, mandibular third molars were 0.55 mm larger and maxillary third molars were 0.7 mm smaller than second molars.

Spontaneous lower arch changes with and without second molar extractions

This study describes the spontaneous changes that occurred in the lower arches of 41 children in whom orthodontic treatment was restricted to the upper arch only. In one group, lower second molars were extracted (n = 18), whereas in the other, these teeth remained in situ (n = 23). A two-phase treatment involved distal movement of the buccal segments with an "en masse" appliance and extraoral traction, followed by edgewise mechanics to retract or align the anterior teeth. Only study casts were examined. The occlusal aspects of the lower casts were recorded with the reflex microscope. Models were examined at the start of treatment, at the completion of buccal segment retraction, and when active appliance therapy was complete. The following arch measurements were recorded: intercanine and intermolar width, arch length and perimeter, and the degree of crowding in both the labial segment and the arch as a whole. In the extraction sample, upper buccal segment retraction was associated with increases in all lower arch dimensions and a reduction of crowding. In the nonextraction group, the response was inconsistent. Although arch length and perimeter reduced, intercanine and intermolar dimensions enlarged with minimal alteration in the labial segment crowding. During the second stage of therapy, dimensions generally decreased: arch length, perimeter, and the intercanine width returned to their pretreatment values in the extraction group and were further reduced in the nonextraction sample. However, both arch length and perimeter remained significantly longer in the extraction group. Intermolar width remained stable in both groups, whereas crowding increased. Over the 2-year observation period, arch length, arch perimeter, and crowding exhibited statistically significant differences in behavior between the two groups.