Treatment change comparisons between skeletal Class I and II white adolescents with 3 different vertical divergencies-part 1: Frankfort-Mandibular Incisor Angle (FMIA) and soft-tissue profile.

INTRODUCTION: This study investigated the interrelationship between FMIA and soft-tissue profile changes in skeletal Class I and II white adolescents with 3 different vertical skeletal patterns. METHODS: Two hundred seventy cephalometric images were constructed from pretreatment and posttreatment cone-beam computed tomography images of 135 white adolescents (69 females and 66 males with a mean age of 12.8 ± 1.4 years pretreatment and 15.0 ± 1.4 years posttreatment). SNA, SNB, ANB, Frankfort Mandibular Angle [FMA], Incisor Mandibular Plane Angle [IMPA], Frankfort-Mandibular Incisor Angle [FMIA], and Z angle were measured. A mixed-model analysis of variance was performed for patients with an increased posttreatment Z angle to evaluate within-subject and between-subject effects of variables in relation to horizontal and vertical skeletal patterns. Post-hoc tests were conducted to identify statistical significance among the 3 different divergent subgroups. RESULTS: Patients with a skeletal Class I relationship had straighter facial profiles and a larger FMIA than patients with a skeletal Class II relationship before and after treatment. FMA, FMIA, IMPA, and Z angle treatment changes were similar between the skeletal Class I and II groups. The final FMIA means of the 3 divergent subgroups converged at 65° in the skeletal Class I group and 60° in the skeletal Class II group. The mandibular incisors were uprighted during treatment in the hyperdivergent patients whose Z angle values increased after treatment. CONCLUSION: Horizontal skeletal relationships seem more suitable for determining the desired FMIA in Tweed's total space analysis than vertical skeletal divergencies.

The congenitally missing second premolar: Space closure. A viable option.

Many treatment options are available to address the problem of missing second premolars. Extraction of retained deciduous second molars and subsequent space closure are often appropriate because this option alleviates the need for implants or other restorations. This article describes the conventional orthodontic closure of unilateral and bilateral congenitally missing second premolar spaces after the extraction of retained deciduous second molars.

Class II correction: Extraction or nonextraction?

The patient with a Class II malocclusion, proclination, or moderate crowding of the mandibular anterior teeth, and a moderate-to-low mandibular plane angle is a treatment-planning challenge. The records of 3 patients are presented. For 2 of them, extraction treatment was used to resolve the Class II malocclusion problem. Each of these patients was treated with the removal of maxillary first premolars and mandibular second premolars. The third patient was treated with Class II elastics without extractions. The clinician must weigh the pros and cons of each approach and decide which approach will give the patient the best long-term benefit.

Extraction vs no treatment: Long-term facial profile changes.

INTRODUCTION: Long-term soft tissue response to extraction orthodontic treatment has been a subject of interest for years. The purposes of this study were to investigate long-term soft tissue profile changes in an extraction sample and to compare them with profile changes in an untreated sample. METHODS: A premolar extraction-treated sample (n = 47) and an untreated control sample (n = 57) were studied. Descriptive statistics were collected, and individual t tests were used for comparison and contrast of the treated and untreated samples. RESULTS: We found that the untreated soft tissue profile changed in the downward and forward direction. The treated soft tissue profile change was similar, but with more of a forward component than in the untreated sample. Most noteworthy was the finding that the soft tissue profiles of both the untreated and the treated samples were similar at the end point. CONCLUSIONS: The following conclusions were derived from the study. (1) There was no substantive difference in the soft tissue profiles of the samples, but there were some differences in the directional changes between them. (2) The changes for the untreated sample were the greatest for the lips and the chin, with the change occurring in the downward and forward direction. (3) The soft tissue profiles of the extraction sample also had the greatest measurable changes in the lips and the chin, but the changes had more of a forward component than they did in the untreated sample. (4) Extraction treatment does not adversely impact soft tissue profile changes over time.

Long-term mandibular skeletal and dental effects of standard edgewise treatment.

INTRODUCTION: The purpose of this investigation was to examine the effect of Tweed edgewise treatment on the expression of mandibular growth in the horizontal direction through maintenance of vertical control. METHODS: We studied 36 patients who had 4 premolars extracted during treatment. Pretreatment, posttreatment, and postretention records of these patients were matched by age (± 6 months), sex, malocclusion, and treatment interval (± 6 months) to untreated controls from the Bolton-Brush Growth Study Center, Cleveland, Ohio. The cephalograms of the 2 samples were traced, digitized, and analyzed by descriptive cephalometric analysis and detailed regional superimposition. RESULTS: Tweed edgewise treatment can prevent clockwise rotation but was not observed to enhance the normal forward rotation of the mandible. The mandible did not rotate forward in the treated patients who underwent a greater chin advancement. CONCLUSIONS: The pattern of skeletal change was favorable both during treatment and in later years. A feature of this effect was an improved pattern of mandibular growth displacement, when mandibular change was compared with maxillary change.

Relapse revisited--again.

INTRODUCTION: Long-term changes in the dentitions of orthodontic patients have been studied. However, most studies in the literature report findings after only a few years posttreatment. In this study, we examined records an average of 24 years after active treatment. The purpose was to answer 2 questions: (1) does irregularity increase with time after treatment, and (2) how much relapse can be expected if a conservatively treated sample is recalled 2.5 decades after active treatment? METHODS: The sample consisted of dental casts of 52 women who were treated in the mid-1970s to the early 1980s with 0.022 × 0.028-in standard edgewise appliances. Each was given a maxillary Hawley retainer and either a mandibular Hawley or a banded canine-to-canine retainer at debanding. Retention lasted 24 to 32 months. The same practitioner treated all the patients. The sample is one of convenience; specifically, inclusion depended only on each patient's willingness to return for a recall examination. Records were collected at 3 examinations for each patient: start of treatment, end of the active phase of treatment, and long-term retention recall. The long-term maxillary and mandibular casts were measured and occluded in maximum intercuspation. Variables were measured, including incisor overjet and overbite, buccal segment relationship of the first molars and canines, and incisor irregularity in each arch. Variables were measured on the casts with digital readout sliding calipers precise to 0.001 mm. RESULTS: Mandibular incisor irregularity at recall was less than 3.5 mm in 77% of the patients examined. Correction of the maxillary incisor irregularity remained relatively stable over the time interval studied. Buccal segment Class II correction remained stable at the recall examination. CONCLUSIONS: Orthodontic treatment can yield reasonably good long-term stability in both occlusal correction and tooth alignment.

Is the benefit of early orthodontic treatment worth the burden?

In summary, early interception of Class III malocclusion is definitely warranted for many patients. A careful analysis of the patient's problem, and an analysis of the patient's airway is essential if one is to make the correct decision as to the amenability of early treatment of the patient's Class III malocclusion. The Class I patient, in most instances, especially if the crowding is severe, can be favorably impacted with guidance of occlusion. This procedure shortens treatment time and lessens the burden for both the patient and the family. Space preservation is also a viable procedure if the Class I patient has minor mandibular anterior crowding. Early Class II intervention can be attempted if all parties concerned know the literature and expectations. Of the three types of malocclusions, the Class II malocclusion presents with the most problems, and early Class II treatment must be viewed pessimistically.

The vertical dimension: the "low-angle" patient.

The patient who has a diminished anterior facial height and excess posterior facial height must be treated with a "different" diagnosis and treatment plan. The mandibular incisors must be left in their pretreatment positions--or facial balance will be compromised. They must not be proclined to eliminate crowding or to level a curve of Spee. The three most common diagnostic "schemes" for these patients are: (1) third molar extraction; (2) maxillary first premolar and mandibular third molar extraction; and (3) maxillary first premolar and mandibular second premolar extraction. This article will attempt to explain why certain diagnostic decisions are made. Case reports are used to illustrate the three most common treatment plans.