Vrije Universiteit Brussel Treatment of Class II , 2 Malocclusion Using a New Herbst - Type Appliance

When correcting a Class II malocclusion, an orthodontist is often dependent on patients’ cooperation. If cooperation is bad, it is difficult to achieve the preset treatment goals. Appliances have been developed to reduce the necessity of patient cooperation. Therapy with these kinds of appliances is called non-compliance therapy. By using this kind of therapy, a greater control over the treatment lies within the hands of the orthodontist. By improving the control over the treatment, results can be improved. Besides a case report, theory behind these appliances, biomechanics and a couple of appliances are discussed in this article. INTRODUCTION The use of the Herbst appliance recaptured the interest of the orthodontic community following Pancherz’s 1979 seminal publication [1]. The mandibular advancement induced and sustained by the appliance contributes to the successful Class II molar relationship and overjet correction, which can be attributed to about equal skeletal and dental changes. These changes could be summarized to an increase in mandibular length, distal movement of maxillary molars, and mesial movement of mandibular molars [2]. In a recent 32-year follow up studybased on casts from 14 adolescents with Class II, division 1 malocclusions followed to middle life, the long-term effects of Herbst treatment on tooth position and occlusion were analyzed. The results of this type of therapy on the molar relationship were found to be stable in about 2/3 of the studied group with most of the post-treatment changes occurring during the first 6 years after treatment [3]. The Class II molar and overjet relapses could be explained by an unfavorable post-treatment maxillomandibular growth pattern, combined with unstable teeth inderdigitation [4]. Findings regarding the long-term effects of the Herbst appliance on TMJ disorders are not different than those corresponding to the general population [5]. However, and despite the successful treatment outcomes the appliance has not gained widespread acceptance and use due to its complex manufacturing and bonding process. Various modifications and alternatives have been proposed over the years to simplify the use and minimize the number of undesirable incidents and side-effects [6–11]. A major advantage of these appliances is that they do not require the patient’s compliance and can be utilized in conjunction with orthodontic brackets. The aim of this paper is to describe the use of a new fixed functional appliance with rigid arms which may be used alternatively to the Herbst, and simultaneously with full fixed mechanisms to effectively treat different types of Class II malocclusions. CASE PRESENTATION The patient was a 13-year old female with a chief complaint of ‘’protruding and irregular upper teeth’’. The clinical examination revealed a convex profile with a retrusive mandible, and a Class II, division 2, malocclusion. The overjet was 4 mm and the overbite 5 mm, with marked crowding in the maxillary arch (Figure 1-8). The cephalogramand the analysis of it confirmed the clinical findings indicating a well-positioned maxilla, a retrognathic mandible, and a tendency for a skeletal deep bite (Figure 9, Table 1). The panoramic radiograph showed the presence of third molars (Figure 10). The overall treatment goal was to improve the convex profile and obtain a Class I occlusion with ideal overjet and overbite without extracting teeth. A fixed functional appliance (in this case the biobitecorrector®) (BBC) would be used to aid in skeletal correction. Treatment was initiated with full fixed, self-ligating appliances (0.022 slot) to promote leveling, alignment, and change in maxillary incisor inclination that would allow the seamless application of the biobitecorrector at a later stage. The sequence of archwires used was .014 Ni-Ti, .018 Ni-Ti, .017x.025 Ni-Ti, and .019x.025 stainless steel, and each one of them was left in the mouth for a period of one month. Vande Vannet et al. (2015) Email: JSM Dent 4(1): 1055 (2016) 2/6 Central were inserted in combination with Class II elastics (5/16, 4 oz.), to support the sagittal correction achieved. Treatment with the self-ligating fixed appliances continued for another five months and the patient was finally debonded. The total treatment time was 15 months (Figure 13-18). The occlusal correction was retained using two removable wrap-around appliances. DISCUSSION Mandibular retrusion is the most prevailing characteristic feature of Class II malocclusion [12]. Redirecting and modifying mandibular growth would then be the natural main goals in a Class II treatment protocol as facial aesthetics can be improved by such an approach. Removable (RA) and fixed functional (FFA) appliances have been utilized for this purpose withthe FFA group potentiallysubdivided into three subgroups: the semi-elastic (e.g. Jusper Jumper, Twin Force, Eureka Spring), the rigid (Herbst, MARA, etc.), and the hybrid -with both rigid and flexible partsFigure 1 Pretreatment extraoral and intraoral photographs of the patient. Figure 2 Pretreatment extraoral and intraoral photographs of the patient. Figure 3 Pretreatment extraoral and intraoral photographs of the patient. Figure 4 Pretreatment extraoral and intraoral photographs of the patient. Consequently, after 4 months, it was possible to placethe BBCon a.019x.025 stainless steel straightwire (the presence of a minimum .017 x .025 stainless steel wire is required before inserting the BBC). The rigid multitelescopic telescopic arms of the appliancewere adjusted using the appropriate ‘spacers’ as to produceand maintain a Class I molar and canine interarchrelationship (Figure 11,12). The BBC was employed for a period of seven months, and following its removal, upper and lower .016 x .022 Ni-Ti wires Figure 5 Pretreatment extraoral and intraoral photographs of the patient. Figure 6 Pretreatment extraoral and intraoral photographs of the patient. Figure 7 Pretreatment extraoral and intraoral photographs of the patient. Vande Vannet et al. (2015) Email: JSM Dent 4(1): 1055 (2016) 3/6 Central Figure 8 Pretreatment extraoral and intraoral photographs of the patient. Figure 9 Post-treatment extraoral and intraoral photographs. Figure 10 Post-treatment extraoral and intraoral photographs. Table 1: Selected variables of the cephalometric analysis before treatment. Variable Value SNA 90 ̊ SNB 82 ̊ ANB 8 ̊ GoGnSN 20 ̊ Maxillary Incisor/SN 110 ̊ Mandibular Incisor/ML 96.5 ̊ FH/Tangent to the facial of U1 75 ̊ Figure 11 Post-treatment extraoral and intraoral photographs. Figure 12 Post-treatment extraoral and intraoral photographs. Figure 13 Post-treatment extraoral and intraoral photographs. Figure 14 Post-treatment extraoral and intraoral photographs. Vande Vannet et al. (2015) Email: JSM Dent 4(1): 1055 (2016) 4/6 Central (e.g. Forsus Spring, Powerscope) Class II correctors. All these three types of appliances have demonstrated similar effectiveness in correcting the Class II dentoskeletal discrepancies [13–17]. It has been shown that a clinically significant supplementary elongation in total mandibular length of more than 2.0 mm is the result of the overall active treatment with functional appliances. This is accompanied by a reduction in forward growth of the maxilla, and the Herbst, and Twin-block appliances seem to have had the highest coefficient of efficiency [17]. The semielastic appliances when used in adolescent patients with Class II malocclusion seem to produce mainly dentoalveolar effects [18]. The Biobitecorrector® presented in this report belongs to the rigid bite-jumping devices and is introduced as an alternative to the Herbst appliance. It has been well documented that Herbst treatment benefits the aesthetics of the profile [19].. Asit can be seen from the analysis of the cephalometric radiograph taken following the completion of treatment (Figure 19, Table 2) some mild maxillary growth restriction (SNA was reduced from 90 ̊ to 88 ̊), favorable changes to the SNB (pre-treatment: 82 ̊, posttreatment: 84 ̊), and ANB (which was also reduced from 8 ̊ to 4 ̊) angles with a favorable effect on the profile were induced (Figure 15). The final maxillary incisor inclination (88 ̊) as it defined by the angle between the FH and the tangent to the facial surface of the incisor predisposes to an aesthetically pleasing profile smiling view [20]. The results in this case are not the sole product of the BBC since the final measurements reflect the outcome of the combination of the rigid corrector with full fixed self-ligating brackets. These seem to be in accordance with results previously reported, where fixed functional appliance treatment in combination with multibracket appliances has been shown to be effective in treating Class II malocclusions with skeletal effects when preformed during the pubertal growth phase or even in early and late adulthood [21,22]. Slight mandibular incisor proclination, and maxillary incisorretrusion together with very mild clockwise tipping of the mandibular plane (GoGn/ML initial: 20 ̊, final: 24 ̊) as noted in this patient, are usual findings when similar treatment approaches are adopted [14,23,24]. The amount of bite jumping has been associated with the amount of protrusion, intrusion, and proclination of the mandibular incisors. However, during the multibracket treatment period, relapsing incisor movements occur [24], as probably happened in this case The design of all FFA is compliance-free, but the many difficulties which are encountered in the manufacturing and bonding process [25], and the increased likelihood of complications during treatment [26–28], has deferred many clinicians from using them. The incidence of complications during treatment with different versions of the Herbst appliance Figure 15 Post-treatment extraoral and intraoral photographs. Figure 16 Post-treatment extraoral and intraoral photographs. Figure 17 Post-treatment extraoral and intraoral photographs. Figure 18 Post-treatment extraoral and intraoral photographs. Table 2: Selected variables of the cephalometric analysis after treatment. Variable Value SNA 88 ̊ SNB 84 ̊ ANB 4 ̊ GoGnSN 24 ̊ Maxillary Incisor/SN 107 ̊ Mandibular Incisor/ML 99 ̊ FH/Tangent to the facial of U1 88 ̊ Vande Vannet et al. (2015) Email: JSM Dent 4(1): 1055 (2016) 5/6 Central Figure 19 Cephalometric radiograph with superimposed tracing after treatment. has been reported as high as eight-eight percent [28]. The BBC is manufactured from titanium, and designed to be totally operator depended as it is delivered completely pre-assembled. The design with the ball joints at the end of the telescopes which allow the patient to make sufficient lateral movements in combination with the hardness of the material might have made the present treatment complication-free. Naturally, the possibility for observing complications associated with the BBCwhen a greater number of patients is followed can not be excluded. Appliance acceptance by the patient which may diminish cooperation if not high [29] was excellent, and it may have contributed to the results observed. The mean duration of comprehensive treatment with FFA has been calculated to be approximately 2.4 years [14,30] but this was not the case with the present treatment which lasted only fifteen months. It is not possible to attribute the time difference to the application of this novel device as it would obviously require a proper study design to prove it. A recent systematic review on the true effect of Class II elastics in the treatment of Class II malocclusion, concluded that in the long term the results from using Class II elastics are similar to those from FFA due to natural growth which can mask the effect of the appliances and wipe out the effects of treatment. Therefore, we cannot claim that this case would have been treated inferiorly had Class II elastics been employed from the beginning insteadof approximately one-third of the treatment time. When long-term changes between different types of RA and FFA were considered it seems that there were not significant dentoskeletal differences among the various treatment groups [31], and this case is probably not an exception. The reaction of adult Class II retrognathic patients to this type of treatment is not yet known but it would be interesting to follow such individuals and compare their treatment results with those achieved with other types of FFA [32]. CONCLUSION A Class II division 2 growing patient was treated effectively and efficiently with a novel fixed functional appliance –the Biobitecorrector®which operates in accordance with the Herbst principles, and possibly less complications and better patient acceptance. The skeletal and dentoalveolar changes achieved were beneficial to the both occlusal correction and the aesthetics of the case, and they were similar to those produced by rigid fixed functional appliances. Further collection of sufficient dataclarifying the exact mode of action of the BBC are required.