The use of the lingual arch in the mixed dentition to resolve incisor crowding.

In the mixed dentition, arch length preservation, maintaining the leeway space, can often provide adequate space to resolve lower incisor crowding. Yet the frequency of this occurrence is not known. To obtain this information, lingual arches were placed in the mandibular arches of 107 consecutive mixed dentition patients with incisor crowding to preserve arch length and make the leeway space available to resolve the crowding. Arch length decreased only 0.44 mm whereas the intercanine, interpremolar, and intermolar dimensions increased between 0.72 and 2.27 mm. There was adequate space to resolve the crowding in 65 (60%) of the 107 patients. If perfect arch length preservation had occurred, there would have been adequate space to resolve the crowding in 73 (68%) of the 107 patients. The correlation between leeway space and tooth size-arch size discrepancy was only 0.44.

Distal movement of the maxillary molars.

Molars can be moved distally approximately 1 mm/month with little to no patient cooperation by using intraarch compressed 100 gm NiTi coils or 100 gm looped NiTi wires against the molars supported by a removable modified Nance appliance. When the molars are moved posteriorly by these intraarch mechanisms, anchorage loss occurs and produces an increase in overjet that is generally within acceptable limits. Although molars can be moved posteriorly at any age, an advantageous treatment time is the late mixed dentition.

A strategy for nonextraction Class II treatment.

Class II nonextraction treatment, which commonly includes distal movement of the maxillary molars to correct the molar relationship, most often can be successful when treatment is started in the late-mixed dentition stage of development. At least two factors contribute to this success. One is that the molars can be distalized routinely at this age. The second is that the "E" space is available and can be used either to help correct the molar relationship or to resolve any crowding that may exist. This article describes and illustrates the treatment of a late mixed-dentition patient with this type of Class II nonextraction treatment that includes distal movement of the maxillary molars with a 100 g NiTi coil system and the maintenance of the "E" space with a lip bumper.

Leeway space and the resolution of crowding in the mixed dentition.

The leeway space provides adequate space to resolve crowding that is present in the mixed dentition in the majority of individuals. This space can be maintained by preserving arch length with a lingual arch as the primary teeth begin to exfoliate, unless conditions such as the premature loss of a primary canine require earlier intervention. A lip bumper can also be inserted after the eruption of the first premolars to preserve arch length.

Crowding: timing of treatment.

The late mixed dentition stage of development, after the eruption of the first premolars, is a favorable time to start treatment to resolve crowding. This protocol offers the clinician choices. If nonextraction treatment is preferable, arch length preservation can provide the space for alignment in approximately 75% of all patients with crowding. If extraction treatment is indicated, the first premolars are available.

Longitudinal evaluation of condylar position in extraction and nonextraction treatment.

In 111 patients pretreatment and posttreatment condylar position was evaluated with corrected tomograms taken with the mandible in centric occlusion. Seventy-nine of the patients were treated by nonextraction procedures and 32 were treated by extraction procedures, 27 of the patients with the extraction of one or more premolars and 5 with the extraction of one or more anterior teeth. When the condylar positions before and after treatment were compared in the entire sample of 111 patients, in the nonextraction patients, in the extraction patients, and in extraction patients relative to nonextraction patients, no statistically significant differences were found. Thus condylar position was stable during treatment and did not behave differently under extraction and nonextraction conditions. On an individual basis, condylar retropositioning, as defined in this study, occurred in only nine of the 222 joints examined and was noted in patients treated both with and without extraction.

Japanese NiTi coils used to move molars distally.

Japanese NiTi superelastic coils, exerting 100 gm of force, were compressed against the maxillary first molars and moved the molars distally 1 to 1.5 mm/month. Anchorage was obtained with a modified Nance appliance cemented onto the first premolars in conjunction with a fixed appliance.

Condylar position and maxillary first premolar extraction.

Condylar position in 17 patients whose Class II treatment (14 with edgewise appliances and 3 with Begg appliances) included extraction of the maxillary first premolars and in 17 control patients was compared by means of corrected tomography. The condyles in both groups were in an anterior position, and there were no statistical differences between the groups. In addition, no statistical correlation was found when the posttreatment bite depth, interincisal angle, and maxillary incisor inclination were correlated with condylar position. Thus, as determined in this study, condylar position was unrelated to treatment, bite depth, interincisal angle, and maxillary incisor inclination.

Condylar position and Class II deep-bite, no-overjet malocclusions.

By means of corrected tomography, the positions of the condyles in 19 click-free persons with Class II malocclusions characterized by a bite depth greater than 50%, no overjet, and an interincisal angle of greater than 140 degrees were compared with a positions of the condyles in 21 control subjects. Average condylar position in both groups was concentric and no significant differences between groups were found. In addition, no significant correlation was noted when condylar position was related to bite depth.

[Asymmetrical distalization of upper molars with magnets. A clinical case]. / Distalizzazione asimmetrica di molare superiore con magneti: caso clinico.

The treatment of a patient with an asymmetric malocclusion (class II, division I--subdivision) was presented. The treatment involved the use of repelling magnets for the distalization of the upper right molar which was in a class II relationship. A fixed "Nance" appliance attached to the second premolars was used for anchorage. Magnets are relatively easy to insert, are well tolerated, and they can distalize molars rapidly without significant loss of anchorage. No cooperation was required during the distalization phase of treatment and the second premolar distalized spontaneously once the "Nance" appliance was removed.

The use of magnets to move molars distally.

Repelling magnets, which were anchored to a modified Nance appliance cemented on the first premolars, were activated against the maxillary first molars to move them distally. Eighty percent of the space created represented distal movement of the first molars.

Condylar position and extraction treatment.

By means of corrected tomography, the positions of the condyles in patients who had undergone four-premolar extraction treatment (20 edgewise and 7 Begg) were compared with the condylar positions of patients who had not yet received orthodontic treatment. No significant between-group differences in condylar position were noted. In addition, the relationship between bite depth and condylar position was examined and no significant correlation was found. Thus, as performed in this study, condylar position was unrelated to extraction treatment and to bite depth.