Stability of Class II treatment with the Bionator followed by fixed appliances

Manoela Fávaro FRANCISCONI José Fernando Castanha HENRIQUES Guilherme JANSON Karina Maria Salvatore de FREITAS Patrícia Bittencourt Dutra dos SANTOS About the authors

Abstract

Objective:

This prospective study assessed the stability of Class II treatment with the Bionator, followed by fixed appliances, 10 years after treatment.

Material and Methods:

The experimental group comprised 23 patients of both sexes (10 boys, 13 girls) at a mean initial age of 11.74 years (late mixed or early permanent dentitions), treated for a mean period of 3.55 years who were evaluated at three stages: initial (T1), final (T2) and long-term posttreatment (T3). A total of 69 lateral cephalograms were evaluated and 69 dental casts were measured using the PAR index. The difference between initial and final PAR indexes, the percentage of occlusal improvement obtained with therapy and the percentage of relapse were calculated, using the PAR index. The variables were compared by repeated measures analysis of variance (ANOVA) followed by Tukey tests.

Results:

The significant improvement in apical base relationship, the palatal inclination of the maxillary incisors and the labial inclination of the mandibular incisors, and the significant improvement in molar relationship and reduction of overjet and overbite, obtained with treatment, remained stable in the long-term posttreatment period. There was also significant improvement in the occlusal relationships which remained stable in the long-term posttreatment period. The percentage of occlusal improvement obtained was of 81.78% and the percentage of relapse was of 4.90%.

Conclusions:

Treatment of Class II division 1 malocclusions with the Bionator associated with fixed appliances showed to be stable in the long-term posttreatment period.

Orthodontics; Recurrence; Malocclusion; Angle Class II; Functional orthodontic appliances


INTRODUCTION

The combined use of functional and fixed appliances for treatment of certain malocclusions, in determined periods of the growth, can generate greater outcomes than that achieved by the use of functional or fixed appliances separately. Orthodontists should, therefore, consider this possibility when dealing with multiple factors that determine a malocclusion1919- Miguel JA, Cunha DL, Calheiros AA, Koo D. Rationale for referring Class II patients for early orthodontic treatment. J Appl Oral Sci. 2005;13:312-7..

After its introduction in 1964, the Bionator has been the object of several investigations aimed to identify both the dentoalveolar and skeletal effects of this appliance. Most studies dealt with short-term outcomes of Bionator therapy by using various types of control groups (untreated Class I or Class II subjects)11- Almeida MR, Henriques JF, Almeida RR, Almeida-Pedrin RR, Ursi W. Treatment effects produced by the Bionator appliance. Comparison with an untreated Class II sample. Eur J Orthod. 2004;26:65-72.,33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98..

In general, correction of Class II, division 1 by combined orthopedic-orthodontic therapy is related to skeletal and dental factors. Retraction and uprighting of the maxillary incisors, associated with proclination of the mandibular incisors; increase in mandibular molar eruption; no skeletal modification of the maxilla and favorable increase in total mandibular length have been consistently described in cases treated with the Bionator1616- Lange DW, Kalra V, Broadbent BH Jr., Powers M, Nelson S. Changes in soft tissue profile following treatment with the bionator. Angle Orthod. 1995;65:423-30.. However, these changes can be considered satisfactory only if they remain stable. Longitudinal studies show that changes achieved with active treatment tend to undergo relapse toward the original malocclusion in the years following the end of orthodontic treatment2727- Sinclair PM, Little RM. Dentofacial maturation of untreated normals. Am J Orthod. 1985;88:146-56.. The relationship between teeth and bone bases does not necessarily remain constant over the years, but can often be changed during growth. It is possible that many orthodontic relapse cases represent only the results of an unfavorable posttreatment growth2727- Sinclair PM, Little RM. Dentofacial maturation of untreated normals. Am J Orthod. 1985;88:146-56.. In addition, bucofacial muscles exert a great influence on the development of the face and teeth. After the correction of Class II malocclusion, the final disposition of the teeth is a reflection of the result of the interaction of hard and soft tissues22- Bass NM. Dento-facial orthopaedics in the correction of class II malocclusion. Br J Orthod. 1982;9:3-31.. Many orthodontists believe that is possible to prevent relapse by positioning teeth in harmony with the lips, cheeks and tongue; eliminating harmful habits, using appropriate retention and establishing a favorable occlusion1111- Gottlieb EL. Relapse. J Clin Orthod. 1971;5:417-8..

Therefore, because stability is known to be the fundamental key to the successful outcome of orthodontic treatment, this prospective study investigated stability of the occlusal and dentoskeletal changes 10 years after treatment with the Bionator, followed by fixed appliances.

MATERIAL AND METHODS

This study was approved by the Ethics in Research Committee of Bauru School of Dentistry, and all subjects signed informed consent.

The sample size was calculated based on an alpha significance level of 0.05 and a beta of 0.2 to achieve 80% of power to detect a mean difference of 0.5º with a standard deviation of 0.5º in ANB angle change between the posttreatment and long-term posttreatment stages1010- Dyken RA, Sadowsky PL, Hurst D. Orthodontic outcomes assessment using the peer assessment rating index. Angle Orthod. 2001;71:164-9.. The sample size calculation showed that 9 patients were needed, and to increase the power even more it was decided to select 23 patients for the experimental group.

Therefore, 69 lateral cephalometric headfilms and dental casts of 23 Class II division 1 malocclusion patients (10 male; 13 female) who were treated with Balters' Bionator followed by fixed appliances, were collected from the files of the Orthodontic Department at Bauru School of Dentistry, University of São Paulo.

The sample was selected according to the following inclusion criteria: in the late mixed or early permanent dentitions; at least half-cusp bilateral Class II molar relationship and 5 mm of overjet; absence of agenesis, supernumerary or lost teeth; convex profile; without history of previous orthodontic treatment3030- Wheeler TT, McGorray SP, Dolce C, Taylor MG, King GJ. Effectiveness of early treatment of Class II malocclusion. Am J Orthod Dentofacial Orthop. 2002;121:9-17.. No cephalometric characteristic was considered as inclusion criteria.

The treatment protocol consisted of Class II correction with the Bionator during a mean period of 1.52 years (S.D.=0.79, range from 0.41 to 3.08 years) (Table 1) constructed with coverage of the mandibular incisors (Figure 1), followed by a mean period of 1.76 years (S.D.=0.94, range from 0.56 to 4.45 years) (Table 1) of fixed appliance therapy, after correction of the Class II anteroposterior discrepancy, for leveling and alignment of the teeth and to refine the occlusion. In all cases, after correction with the Bionator, active retention was made with Class II intermaxillary elastics. After comprehensive treatment, each patient was given a fixed mandibular canine-to-canine retainer and a Hawley plate. Maxillary removable Hawley retainers were worn all day long for 6 months and only during sleeping for additional 6 months, and mandibular fixed canine-to-canine retainers were used for a minimum period of five years or until the end of growth.

Table 1
Mean, standard deviation (SD), minimum and maximum values of the ages at T1, T2 and T3 and of the treatment with the Bionator, fixed appliance, and both (T1-T2) and long-term posttreatment (T2-T3) periods
Figure 1
Balters' Bionator with coverage of the mandibular incisors

The patients were evaluated at three stages (Table 1): initial (T1), final (T2), and long-term posttreatment (T3). The mean initial age was 11.74 years (S.D.=1.30, range 9.92 to 14.42), the mean final age was 15.38 years (S.D.=1.69, range 13.00 to 19.50 years) and the mean age at the long-term posttreatment stage was 24.99 years (S.D.=3.37, range 18.83 to 32.92 years). All patients were treated non-extraction for a mean period of 3.55 years (S.D.=2.14; range 1.08 to 7.33 years). As this research aimed to investigate treatment stability, the selected subjects had to have been out of treatment for five years, at least. The mean long-term posttreatment period was 9.91 years (S.D.=3.66, range 5.00 to 17.42 years).

The anatomic tracing and location of dentoskeletal landmarks were manually carried out by a single investigator (M.F.F.) and digitized (Numonics AccuGrid XNT, model A30TL.F - Numonics Corporation, Montgomeryville, Penn, USA). These data were then stored in a computer and analyzed with Dentofacial Planner 7.2 (Dentofacial Planner Software Inc., Toronto, Ontario, Canada). This software also corrected the magnification factor (6% and 9.8%) of the radiographic images and calculated the angular and linear cephalometric variables employed in this study. The unusual cephalometric variables are illustrated in Figures 2 and 3.

Figure 2
Definitions of abbreviations of unusual cephalometric variables used1212- Holdaway RA. A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part I. Am J Orthod. 1983;84:1-28.,1818- McNamara JA Jr. A method of cephalometric evaluation. Am J Orthod. 1984;86:449-69.2424- Ricketts RM. A four-step method to distinguish orthodontic changes from natural growth. J Clin Orthod. 1975;9:208-15,218-28.,2828- Steiner CL. Cephalometrics as a clinical tool. Philadelphia: Lea & Fabiger; 1962.
Figure 3
Cephalometric variables: 1) LAFH; 2) S-Go; 3) 1-NA; 4) 1.NA; 5) 1-NB; 6) 1.NB; 7) Nasolabial angle

The peer assessment rating (PAR) index2323- Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992;14:125-39. was calculated on the dental casts of each patient according to the American weightings suggested by De Guzman, et al.66- De Guzman L, Bahiraei D, Vig KW, Vig PS, Weyant RJ, O'Brien K. The validation of the Peer Assessment Rating index for malocclusion severity and treatment difficulty. Am J Orthod Dentofacial Orthop. 1995;107:172-6. (1995). The index was ranked by scores for molar and premolar anteroposterior (AP) relationship, overjet (OJ), overbite (OB), crowding and midline to quantify the initial malocclusion severity (PAR1), the treatment occlusal results (PAR2), the occlusal status at the long-term posttreatment stage (PAR3), the amount of treatment (PAR1-PAR2) and long-term posttreatment changes (PAR3-PAR2) and the percentage of PAR treatment and long-term posttreatment changes66- De Guzman L, Bahiraei D, Vig KW, Vig PS, Weyant RJ, O'Brien K. The validation of the Peer Assessment Rating index for malocclusion severity and treatment difficulty. Am J Orthod Dentofacial Orthop. 1995;107:172-6.,2323- Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992;14:125-39., which are better estimates of the occlusal changes1010- Dyken RA, Sadowsky PL, Hurst D. Orthodontic outcomes assessment using the peer assessment rating index. Angle Orthod. 2001;71:164-9..

Error study

Twenty four lateral cephalograms and dental casts were randomly selected, retraced, redigitized, and remeasured by the same examiner (M.F.F.) after a 30-day interval. Casual and systematic errors were calculated comparing the first and second measurements with Dahlberg's formula55- Dahlberg G. Statistical methods for medical and biological students. New York: Interscience; 1940. and dependent t-tests, respectively, at a significance level of 5%.

Statistical analyses

Normal distribution was evaluated with Kolmogorov-Smirnov tests. Because all variables showed normal distribution, repeated measures ANOVA, followed by Tukey tests were used to compare the variables at the three stages. The statistical tests were performed with Statistica software (Statistica for Windows 6.0; Statsoft, Tulsa, Okla, USA). Results were considered significant for P<0.05.

RESULTS

Only 3 (SN.GoGn, S-Go and 6-PP) of the 16 evaluated variables showed statistically significant systematic errors, and no variable showed casual errors greater than 1.0 mm or 1.5º.

There were no significant changes in the maxillary component with treatment, but there was significant increase in the effective maxillary length in the long-term posttreatment period (Table 2). Treatment produced a significant increase in mandibular protrusion and in the effective mandibular length, which also significantly increased in the long-term posttreatment period. These changes contributed to a significant improvement in apical base relationship, which remained stable. The facial pattern angle remained stable with treatment but significantly reduced in the long-term posttreatment period. There were significant increases in anterior and posterior face heights with treatment and in the long-term posttreatment period. The maxillary incisors presented a significant palatal inclination and remained stable afterwards. The mandibular incisors presented significant labial inclination and protrusion which remained stable afterwards. Treatment also produced significant improvement in molar relationship and reduction of overjet and overbite, which remained stable in the long-term posttreatment period.

Table 2
Comparison of the cephalometric variables at the three stages (repeated measures ANOVA followed by Tukey tests)

There was significant reduction of the PAR index during treatment which remained stable in the long-term posttreatment period (Table 3). The percentage of occlusal improvement obtained with treatment was 81.78% and the percentage of occlusal relapse was 4.90% (Table 4).

Table 3
Comparison of the occlusal statuses at the three stages (repeated measures ANOVA followed by Tukey tests)
Table 4
Results of the peer assessment rating (PAR) index changes during treatment and during the long-term posttreatment period

DISCUSSION

Sample and methodology

Even though the Bionator has been part of routine functional appliance therapy for nearly four decades, surprisingly few methodologically sound clinical studies of this treatment approach, at least by today's standards, have appeared in the orthodontic literature33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98.. Although several cephalometric investigations on the short-term treatment effects of the Bionator appliance in growing subjects with Class II malocclusion have been published33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98.,2626- Rudzki-Janson I, Noachtar R. Functional appliance therapy with the Bionator. Semin Orthod. 1998;4:33-45., no previous research has dealt with the issue of long-term response to this type of therapy. Since stability is known to be the fundamental key to successful outcome of orthodontic treatment, this prospective study investigated the stability of dentoskeletal changes 9.91 years after treatment with Balters' Bionator, followed by fixed appliances. Consequently, the results are due to several effects of the Balters' Bionator associated with fixed appliances.

The absence of a control group is a shortcoming of the present study. Nevertheless, relevant information can still be obtained in the long-term posttreatment period.

Maxillary component

There were no significant changes in any of the two variables used to evaluate the maxillary component between the initial (T1) and final (T2) stages (Table 2). These results are in agreement with previous studies that also found no significant restriction of maxillary growth with Bionator treatment33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98.. Only changes in the effective maxillary length showed a statistically significant increase in the long-term posttreatment stage, which were possibly consequent to normal growth and development.

Mandibular component

A statistically significant increase in mandibular protrusion and length was observed during treatment, which is in agreement with the results of a number of investigations involving the Bionator/activator appliance11- Almeida MR, Henriques JF, Almeida RR, Almeida-Pedrin RR, Ursi W. Treatment effects produced by the Bionator appliance. Comparison with an untreated Class II sample. Eur J Orthod. 2004;26:65-72.,33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,88- DeVincenzo JP. Changes in mandibular length before, during, and after successful orthopedic correction of Class II malocclusions, using a functional appliance. Am J Orthod Dentofacial Orthop. 1991;99:241-57.,1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98. (Table 2). Mandibular length continued to significantly increase in the posttreatment period probably consequent to normal growth. This can contribute to stability of Class II relationship correction, but it did not contribute to further significant increase in mandibular protrusion.

Maxillomandibular relationship

The maxillomandibular relationship showed significant improvement during treatment and remained stable in the long-term posttreatment period (Table 2). Improvement in basal bone relationship during treatment resulted from the significant mandibular growth and protrusion, as previously discussed. Similar findings were obtained with the Bionator/activator therapy11- Almeida MR, Henriques JF, Almeida RR, Almeida-Pedrin RR, Ursi W. Treatment effects produced by the Bionator appliance. Comparison with an untreated Class II sample. Eur J Orthod. 2004;26:65-72.,2929- Tulloch JF, Phillips C, Koch G, Proffit WR. The effect of early intervention on skeletal pattern in Class II malocclusion: a randomized clinical trial. Am J Orthod Dentofacial Orthop. 1997;111:391-400.. Most important is that the maxillomandibular relationship achieved with Bionator treatment remained stable in the long-term posttreatment period, similarly to non-extraction Class II malocclusion treatment with other appliances2222- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34..

Facial pattern

The mandibular plane angle was unaffected during treatment1717- Maltagliati LA, Henriques JF, Janson G, Almeida RR, Freitas MR. Influence of orthopedic treatment on hard and soft facial structures of individuals presenting with Class II, Division 1 malocclusion: a comparative study. J Appl Oral Sci. 2004;12:164-70., while in the long-term posttreatment period it experienced a counterclockwise rotation. Growth that usually takes place in the long-term posttreatment period is characterized by mandibular counterclockwise rotation in response to vertical redirection of condylar growth2020- Monini AC, Gandini Junior LG, Martins LP, Raveli DB. Longitudinal study on skeletal changes during and after bionator therapy using metallic implants. Braz J Oral Sci. 2010;9:33-8. (Table 2).

Vertical component

Lower anterior face height and posterior face height significantly increased during treatment and in the posttreatment period (Table 2). Usually, during treatment with a functional appliance they significantly increase more than a control group and this is regarded as an effect of these appliances33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,1313- Janson G, Caffer DC, Henriques JF, Freitas MR, Neves LS. Stability of Class II, division 1 treatment with the headgear-activator combination followed by the edgewise appliance. Angle Orthod. 2004;74:594-604.. However, the significant increase in the posttreatment period can only be regarded as consequent to normal growth and development77- Derringer K. A cephalometric study to compare the effects of cervical traction and Andresen therapy in the treatment of Class II division 1 malocclusion. Part 1 - Skeletal changes. Br J Orthod. 1990;17:33-46..

Maxillary dentoalveolar component

The maxillary incisors were palatally tipped during treatment and remained stable in the long-term posttreatment period (Table 2). Palatal movement of the maxillary incisors with the use of the Bionator associated to fixed appliances has already been described in several studies which showed that almost all functional appliances produce palatal tipping of the maxillary incisors33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,99- Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13.,1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98.,2222- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34..

There was stability of the sagittal position of the maxillary incisors as observed in the long-term posttreatment stage, which is similar to non-extraction treatment with other appliances99- Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13.,1313- Janson G, Caffer DC, Henriques JF, Freitas MR, Neves LS. Stability of Class II, division 1 treatment with the headgear-activator combination followed by the edgewise appliance. Angle Orthod. 2004;74:594-604.,2222- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34..

Mandibular dentoalveolar component

Proclination of the mandibular incisors was produced by the Bionator associated to fixed appliances treatment and remained stable at the long-term posttreatment stage (Table 2). The proclination effect is probably consequent to the resultant mesial force on the mandibular incisors induced by mandibular protrusion. This finding corroborates the results of previous reports1414- Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98.. It is interesting to notice that even if some proclination of the mandibular incisor occurs in non-extraction Class II malocclusion treatment, it is able to remain stable, as also observed with other treatment modalities99- Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13.,1313- Janson G, Caffer DC, Henriques JF, Freitas MR, Neves LS. Stability of Class II, division 1 treatment with the headgear-activator combination followed by the edgewise appliance. Angle Orthod. 2004;74:594-604.,2222- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34..

Dental relationships

There was significant molar relationship correction with treatment, which remained stable at the long-term posttreatment stage2121- Oltramari PV, Conti AC, Navarro RL, Almeida MR, Almeida-Pedrin RR, Ferreira FP. Importance of occlusion aspects in the completion of orthodontic treatment. Braz Dent J. 2007;18:78-82. (Table 2). Many studies showed the same treatment effects and stability with other orthopedic appliances1515- Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56..

There was decrease in the overjet during treatment and no significant relapse was observed during the long-term posttreatment stage (Table 2). Probably, stability of the sagittal changes of the maxillary and mandibular incisors contributed to stability of the overjet correction. Reduction of the overjet was reported in several studies considering appliances with similar mode of action33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,99- Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13.,1515- Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56.,2222- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34.. Overjet correction was obtained mainly by palatal movement of the maxillary incisors, proclination of mandibular incisors and mandibular normal growth99- Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13..

The overbite significantly decreased during treatment and remained stable at the long-term posttreatment stage2121- Oltramari PV, Conti AC, Navarro RL, Almeida MR, Almeida-Pedrin RR, Ferreira FP. Importance of occlusion aspects in the completion of orthodontic treatment. Braz Dent J. 2007;18:78-82. (Table 2). Similar findings were obtained with other functional appliance therapies1515- Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56..

Soft tissue component

Despite the significant dentoskeletal changes to correct Class II malocclusion with the Bionator, there was no significant change in the nasolabial angle1717- Maltagliati LA, Henriques JF, Janson G, Almeida RR, Freitas MR. Influence of orthopedic treatment on hard and soft facial structures of individuals presenting with Class II, Division 1 malocclusion: a comparative study. J Appl Oral Sci. 2004;12:164-70.. This has also been observed with other functional appliances1515- Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56.. Consequently, there was also stability of the nasolabial angle in the posttreatment period, as observed with other functional appliances1515- Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56.,22 22- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34.as well as with other non-extraction treatment modalities88- DeVincenzo JP. Changes in mandibular length before, during, and after successful orthopedic correction of Class II malocclusions, using a functional appliance. Am J Orthod Dentofacial Orthop. 1991;99:241-57..

Occlusal results

The analysis of the dental casts showed that the values of the PAR index presented a statistically significant reduction with an excellent outcome44- Burden DJ, McGuinness N, Stevenson M, McNamara T. Predictors of outcome among patients with class II division 1 malocclusion treated with fixed appliances in the permanent dentition. Am J Orthod Dentofacial Orthop. 1999;116:452-9., and remained stable at the long-term posttreatment stage (Table 3). There are few studies in the literature evaluating the long-term posttreatment period through the PAR index3131- Woods M, Lee D, Crawford E. Finishing occlusion, degree of stability and the PAR index. Aust Orthod J. 2000;16:9-15..

According to final PAR categories suggested by Richmond, et al.23 23- Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992;14:125-39. (1992), when the value obtained at the end of treatment is equal to or less than 5, the occlusion can be considered to be almost perfect. Patients finished the orthodontic treatment with an average PAR of 5.39, and remained stable (average PAR of 5.60) in the long-term posttreatment period (Table 3). This shows that their occlusions were close to ideal in most patients even 10 years after the end of treatment.

The percentage of occlusal improvement obtained with this therapy was of 81.78%, which is above the value suggested by Richmond, et al.2323- Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992;14:125-39. (1992) and De Guzman, et al.66- De Guzman L, Bahiraei D, Vig KW, Vig PS, Weyant RJ, O'Brien K. The validation of the Peer Assessment Rating index for malocclusion severity and treatment difficulty. Am J Orthod Dentofacial Orthop. 1995;107:172-6. (1995), of 70% and 65%, respectively (Table 4). In agreement with these results, Rodriguez, Hirschheimer and Vigorito2525- Rodriguez GC, Hirschheimer C, Vigorito JW. Transversal changes of the dental arches following bionator therapy in growing patients with class malocclusion. Ortodontia. 2001;34:36-42. (2001) found 55.4% of improvement using only the Bionator in Class II division 1 malocclusion treatment, showing its efficacy in growing patients.

The percentage of relapse obtained with this therapy was of 4.90% implying that stability can be achieved with this type of orthopedic-orthodontic treatment, as with other functional appliances33- Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.,99- Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13.,1515- Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56.,2222- Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34. (Table 4).

CONCLUSIONS

Treatment of Class II division 1 malocclusions with the Bionator associated to fixed appliances showed to be stable in the long-term posttreatment period.

REFERENCES

  • 1
    - Almeida MR, Henriques JF, Almeida RR, Almeida-Pedrin RR, Ursi W. Treatment effects produced by the Bionator appliance. Comparison with an untreated Class II sample. Eur J Orthod. 2004;26:65-72.
  • 2
    - Bass NM. Dento-facial orthopaedics in the correction of class II malocclusion. Br J Orthod. 1982;9:3-31.
  • 3
    - Bolmgren GA, Moshiri F. Bionator treatment in Class II, division 1. Angle Orthod. 1986;56:255-62.
  • 4
    - Burden DJ, McGuinness N, Stevenson M, McNamara T. Predictors of outcome among patients with class II division 1 malocclusion treated with fixed appliances in the permanent dentition. Am J Orthod Dentofacial Orthop. 1999;116:452-9.
  • 5
    - Dahlberg G. Statistical methods for medical and biological students. New York: Interscience; 1940.
  • 6
    - De Guzman L, Bahiraei D, Vig KW, Vig PS, Weyant RJ, O'Brien K. The validation of the Peer Assessment Rating index for malocclusion severity and treatment difficulty. Am J Orthod Dentofacial Orthop. 1995;107:172-6.
  • 7
    - Derringer K. A cephalometric study to compare the effects of cervical traction and Andresen therapy in the treatment of Class II division 1 malocclusion. Part 1 - Skeletal changes. Br J Orthod. 1990;17:33-46.
  • 8
    - DeVincenzo JP. Changes in mandibular length before, during, and after successful orthopedic correction of Class II malocclusions, using a functional appliance. Am J Orthod Dentofacial Orthop. 1991;99:241-57.
  • 9
    - Drage KJ, Hunt NP. Overjet relapse following functional appliance therapy. Br J Orthod. 1990;17:205-13.
  • 10
    - Dyken RA, Sadowsky PL, Hurst D. Orthodontic outcomes assessment using the peer assessment rating index. Angle Orthod. 2001;71:164-9.
  • 11
    - Gottlieb EL. Relapse. J Clin Orthod. 1971;5:417-8.
  • 12
    - Holdaway RA. A soft-tissue cephalometric analysis and its use in orthodontic treatment planning. Part I. Am J Orthod. 1983;84:1-28.
  • 13
    - Janson G, Caffer DC, Henriques JF, Freitas MR, Neves LS. Stability of Class II, division 1 treatment with the headgear-activator combination followed by the edgewise appliance. Angle Orthod. 2004;74:594-604.
  • 14
    - Janson I. A cephalometric study of the efficiency of the bionator. Trans Europ Orthod Soc. 1977;28:283-98.
  • 15
    - Küçükkeleş N, Ilhan I, Orgun IA. Treatment efficiency in skeletal Class II patients treated with the jasper jumper. Angle Orthod. 2007;77(3):449-56.
  • 16
    - Lange DW, Kalra V, Broadbent BH Jr., Powers M, Nelson S. Changes in soft tissue profile following treatment with the bionator. Angle Orthod. 1995;65:423-30.
  • 17
    - Maltagliati LA, Henriques JF, Janson G, Almeida RR, Freitas MR. Influence of orthopedic treatment on hard and soft facial structures of individuals presenting with Class II, Division 1 malocclusion: a comparative study. J Appl Oral Sci. 2004;12:164-70.
  • 18
    - McNamara JA Jr. A method of cephalometric evaluation. Am J Orthod. 1984;86:449-69.
  • 19
    - Miguel JA, Cunha DL, Calheiros AA, Koo D. Rationale for referring Class II patients for early orthodontic treatment. J Appl Oral Sci. 2005;13:312-7.
  • 20
    - Monini AC, Gandini Junior LG, Martins LP, Raveli DB. Longitudinal study on skeletal changes during and after bionator therapy using metallic implants. Braz J Oral Sci. 2010;9:33-8.
  • 21
    - Oltramari PV, Conti AC, Navarro RL, Almeida MR, Almeida-Pedrin RR, Ferreira FP. Importance of occlusion aspects in the completion of orthodontic treatment. Braz Dent J. 2007;18:78-82.
  • 22
    - Pancherz H. A cephalometric analysis of skeletal and dental changes contributing to Class II correction in activator treatment. Am J Orthod. 1984;85:125-34.
  • 23
    - Richmond S, Shaw WC, O'Brien KD, Buchanan IB, Jones R, Stephens CD, et al. The development of the PAR Index (Peer Assessment Rating): reliability and validity. Eur J Orthod. 1992;14:125-39.
  • 24
    - Ricketts RM. A four-step method to distinguish orthodontic changes from natural growth. J Clin Orthod. 1975;9:208-15,218-28.
  • 25
    - Rodriguez GC, Hirschheimer C, Vigorito JW. Transversal changes of the dental arches following bionator therapy in growing patients with class malocclusion. Ortodontia. 2001;34:36-42.
  • 26
    - Rudzki-Janson I, Noachtar R. Functional appliance therapy with the Bionator. Semin Orthod. 1998;4:33-45.
  • 27
    - Sinclair PM, Little RM. Dentofacial maturation of untreated normals. Am J Orthod. 1985;88:146-56.
  • 28
    - Steiner CL. Cephalometrics as a clinical tool. Philadelphia: Lea & Fabiger; 1962.
  • 29
    - Tulloch JF, Phillips C, Koch G, Proffit WR. The effect of early intervention on skeletal pattern in Class II malocclusion: a randomized clinical trial. Am J Orthod Dentofacial Orthop. 1997;111:391-400.
  • 30
    - Wheeler TT, McGorray SP, Dolce C, Taylor MG, King GJ. Effectiveness of early treatment of Class II malocclusion. Am J Orthod Dentofacial Orthop. 2002;121:9-17.
  • 31
    - Woods M, Lee D, Crawford E. Finishing occlusion, degree of stability and the PAR index. Aust Orthod J. 2000;16:9-15.

Publication Dates

  • Publication in this collection
    Dec 2013

History

  • Received
    07 Jan 2013
  • Reviewed
    16 July 2013
  • Accepted
    11 Sept 2013
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