Cephalometric markers to consider in the treatment of Class II Division 1 malocclusion with the bionator

Development of a Prediction Model for Short-Term Success of Functional Treatment of Class II Malocclusion

(1) Background: The nature of the changes that contribute to Class II correction with functional appliances is still controversial. A broad variation in treatment responses has been reported. The purpose of this study was to find cephalometric predictors for individual patient responsiveness to twin-block treatment in patients with Class II Division 1 malocclusion; (2) Methods: The study was performed on a sample of 39 pubertal patients (21 females, 18 males) treated with the twin block appliance. Lateral cephalograms were available at the start of the treatment (T1) and at the end of functional therapy (T2). The outcome variable was the T2–T1 change in the sagittal position of the soft tissue pogonion with respect to the vertical line perpendicular to the Frankfort plane and passing through point subnasale. The predictive variables were age, gender at T1, and all the cephalometric parameters measured T1. Forward stepwise linear regression with p value to enter 0.05 and p value to leave 0.10 was applied; (3) Results: The only significant predictive variable that was selected was the Co–Go–Me angle (p = 0.000); (4) Conclusions: A greater advancement of the soft tissue chin on the profile is expected with smaller pretreatment values of Co–Go–Me angle.

Biomechanics of the mandible and growth extension

BACKGROUND AND OBJECTIVE

One way of determining the direction of growth of the mandible is to consider the temporomandibular joint and movement of the mandible as a four-joint gear system, regarding growth then as an extension of the gear system. Our aim was to examine any correlations between the type of biomechanical growth extension and change in the maxilomandibular relation after Class II therapy.

SUBJECTS AND METHODS

A total of 130 lateral cephalograms-before and after orthodontic treatment-were available from 65 adolescent class II patients with open bite or deep bite. The two lateral cephalograms from each patient were superimposed on the occlusal plane. Cephalometric values and the vertical base point deviation were determined from biomechanical analyses, together with three distances and three angles.

RESULTS

No correlation between the cephalometric data and distances or angles were observed. Although there were no significant differences in the distances, we did note significant differences in all three angles (p < 0.05).

CONCLUSION

If gear system extension during growth is considered, this can be interpreted as meaning that the occlusal plane of those patients with an initially open bite dropped during treatment, but that it rose in patients with an initially deep bite.

The impact of functional jaw orthopedics in subjects with unfavorable Class II skeletal patterns

OBJECTIVE

To evaluate the outcomes of functional jaw orthopedics (FJO) followed by fixed appliances in Class II patients showing cephalometric signs predictive of unfavorable responsiveness to orthopedic treatment.

MATERIALS AND METHODS

A total of 48 treated subjects (20 males, 28 females) with unfavorable Class II malocclusions were treated with FJO at the adolescent growth spurt, followed by fixed appliances. Treatment outcomes were compared with the growth changes in a matched control group of untreated subjects with "unfavorable" Class II malocclusions.

RESULTS

A significant prevalence rate of successful outcome was recorded within the treated group (64.5%). When compared with the untreated controls, both the overall treated group and the successful treated subgroup revealed a significant reduction in maxillary growth and sagittal position, along with a significant enhancement in mandibular length, sagittal advancement of the mandible, and significant improvements in the maxillo-mandibular relationships. Both overjet and molar relation showed significant favorable changes in the treated group.

CONCLUSIONS

FJO at the pubertal spurt followed by fixed appliances is a viable therapeutical option in patients with "unfavorable" Class II malocclusions, although skeletal changes are of minor entity.

Assessment of mandibular growth and response to functional appliance treatment in prepubertal patients with different auxologic categories

OBJECTIVE

To assess mandibular growth and response to functional appliance treatment in different Petrovic's auxologic categories and to investigate diagnostic and prognostic usefulness of the Lavergne-Petrovic's flow diagram.

MATERIALS AND METHODS

Eighteen patients with class II malocclusion (ANB>/=4 degrees , dental class II) were selected and divided into 4 groups according to the auxologic categories. Category 2 group had 4 patients, category 3 group had 5, category 4 group had 5 and category 5 group had 4. In order to obtain patient's growth curves and detect the correct treatment time, patient's height was measured every 3 months. This method was supported by the cervical vertebral maturation method for the assessment of mandibular growth. Functional appliance and/or class II elastics, during the fixed appliance phase, were used to correct skeletal and dental relationships. Average treatment time was 31 months (Range 28-36 months). CoGn and ANB were detected in pre-treatment and post-treatment radiographs in order to assess mandibular growth.

RESULTS

The highest growth was in category 5, the lowest in category 2. Rotational type improvement was generally observed.

CONCLUSIONS

In prepubertal class II patients, treatment success not only depends on appliance choice, clinician's ability and correct treatment time, but also on individual growth potential and facial type. Therefore Lavergne-Petrovic's flow diagram could become a great diagnostic and prognostic aid for the orthodontist.

Prediction of individual mandibular changes induced by functional jaw orthopedics followed by fixed appliances in Class II patients

OBJECTIVE

To identify pretreatment cephalometric variables for the prediction of individual mandibular outcomes of functional jaw orthopedics (FJO) followed by fixed appliances in Class II patients treated at the peak in mandibular growth.

MATERIALS AND METHODS

The study was performed on 51 subjects (24 females, 27 males) with Class II malocclusion. First-phase therapy was accomplished with a twin block in 16 subjects, a stainless steel crown Herbst in 15 subjects, and an acrylic splint Herbst in 20 subjects. Lateral cephalograms were available at the start of treatment with FJO and at the completion of fixed appliance therapy. All subjects received FJO at the peak in mandibular growth (CS 3 at T1). Individual responsiveness to Class II treatment including FJO was defined on the basis of the T2-T1 increment in total mandibular length (Co-Gn) when compared with untreated Class II subjects.

RESULTS

Discriminant analysis identified a single predictive parameter (Co-Go-Me degrees) with a classification power of 80%. Pretreatment vertical and sagittal parameters were not able to improve the prediction based upon the mandibular angle.

CONCLUSIONS

A Class II patient at the peak in skeletal maturation (CS 3) with a pretreatment Co-Go-Me degrees smaller than 125.5 degrees is expected to respond favorably to treatment including FJO. A Class II patient at CS 3 with a pretreatment value for Co-Go-Me degrees greater than 125.5 degrees is expected to respond poorly to treatment including FJO.

Rationale for referring class II patients for early orthodontic treatment

The tendency of indicating early treatment (before growth spurt) when dealing with Angle Class II cases has been noticed, although there is no definite scientific evidence to justify such decision. The aim of this study was to identify the advantages and disadvantages to this approach and which appliances are used for this purpose. For that purpose, a questionnaire containing full records of a Class II patient was sent to two professors of each Orthodontic graduate program in Brazil (n=96, total 192), from which 107 were properly answered. Results demonstrated that the most used appliances were the headgear (80.4%), maxillary splint (50%) and Bionator (44.4%). The benefits most often quoted were increase of patient self-esteem (78.5%) and reduction in the incidence of incisors trauma (63.6%), while the main disadvantage was saturation of patient compliance (73.8%). Considering early Class II treatment, there is still no unanimity as to treating in one or two stages or in selection of appliances. However, the orthodontists should consider the physical situation of the patient, severity of cases and susceptibility of trauma to the maxillary incisors. It is crucial that updated information is given to parents, in order to justify this approach.