ACTIVATOR: SIMPLE YET EFFECTIVE FUNCTIONAL APPLIANCE FOR SKELETAL CLASS II CORRECTION: CASE REPORT 1Dr. Falguni Mehta *, 2 Dr. Dolly Patel, 3 Dr. Nishit Mehta 1Professor, Dept of orthodontics & Dentofacial orthopaedics Govt Dental College & Hospital, Ahmedabad, Gujarat, India 2Professor & Head, Dept of orthodontics & Dentofacial orthopaedics Govt Dental College & Hospital, Ahmedabad, Gujarat, India 3Third year post graduate student Dept of orthodontics & dentofacial orthopaedics, Govt Dental College & Hospital, Ahmedabad, Gujarat, India *Corresponding author: Dr. Falguni Mehta ; Email id :drfalgunimehta1@gmail.com...... ABSTRACT: A Class II malocclusion may result from a mandibular deficiency, maxillary excess or a combination of both, but the most common finding is mandibular skeletal retrusion. Functionaljaw orthopaedic appliances are designed to encourageadaptive skeletal growth by maintaining the mandible in a corrected forward position. The activatordeveloped by Andresen is one of the most widely used. A 12-year-old boy with skeletal Class II malocclusion, a low mandibular planeangle was treated with growth modulation by activator followed by fixed orthodontics for detailing of occlusion.the major effects of the activator treatment in this case has been due to increase in condylar growth and in mandibular base length.further non-extraction fixed orthodontic treatment for proper interdigitation of the dentition also help to maintain the stability of the satisfactory results achieved in this type of cases. KEY WORDS: class II Malocclusion, mandibular retrognathism, functional jaw orthopaedics, Activator... INTRODUCTION Class II malocclusions are one of the most common problems in orthodontic treatment.treatment of class II malocclusion has always been an enigma to the orthodontic fraternity. It ranges from a simple functional appliance to surgical correction. There are a variety of effective treatment modalities to correct them, ranging from headgear and functional appliances to surgical options, depending on the site, age of the patient and severity of problem. Functional appliances are commonly used for the treatment of Class II malocclusions with mandibular deficiency. The treatment goals for these appliances are to reduce the large overjet and correct the sagittal skeletal discrepancy 1. The success of treatment with a functional appliance relies on the patient's cooperation and favourable mandibular growth. Treatment with a functional appliance usually lasts for 9 to 12 months and requires a proper retention time to ensure complete musculoskeletal adaptation. A second stage of treatment with a full-fixed appliance is often required to achieve proper alignment and good dentition 2. interdigitation of the By holding a deficient mandible forward and forcing the patient to function with lower jaw forward, functional appliance can stimulate or accelerate the forward mandibular growth.there are variety of removable 180
functional appliances including activator, Robins aim was to correct the sagittal skeletal monobloc, bionator,bass appliance,twin block 1,etc. discrepancy with growth modulation with The activator and its successors provide a greater functional appliance. contact area with the mandibular teeth and lingual To achieve and maintain Angle s class I molar mucosa, and thus are more effective in stimulating the and canine relationship bilaterally patient to position the mandible forward constantly. To achieve normal overjet and overbite. Here, we are presenting a case of a class II To align and level upper and lower arches and skeletal malocclusion treated by using the time-tested activator appliance. Despite of simple design, activator can be used to change dental relationship in all three planes of space with proper adjustments 3. DIAGNOSIS A 12 year old male patient reported with the chief complaint of forwardly placed upper front teeth.there final finishing and detailing of the occlusion with fixed mechanotherapy. TREATMENT PROGRESS 12 year male with a Class II malocclusion and retrognathic mandible was treated first withactivator for 1 year and 1 month. Construction bite with single advancement was taken and activator was delivered with was history of trauma with Ellis class I fracture in proper patient instuctions. The patient had good relation to upper left central incisor. The patient had a skeletal Class II malocclusion with severe mandibular compliance and maintained good oral hygiene.. After treatment period of 1 year and 1 month with activator, retrognathism, and average mandibular plane patient showed improvement in soft tissue profile with angle(table-1,2,3). The lips were competent, with nonconsonant smile arc and convex soft tissue profile(fig 1-a,b,c). patient had mixed dentition in late transitional period with Angle s class II molar aswell as canine relationship with increased overjet(14 mm) andoverbite(8 mm)(fig 1-d,e.f,g,h).curve of Spee of 4 mm was present. His maxillary incisors were tipped labially of their bony base, and the mandibular incisors were tipped lingually(table-1). There was spacing in upper anterior region. Mesiobuccalrotations were present in upper premolars. The maxillary and mandibular midline were coincident with facial midline.patient was in CVMI stage III 4 with positive VTO. TREATMENT PLANNING Since the patient was in growing stage with favourable growth pattern and positive VTO, class I molar and canine relationship bilaterally(fig 2-a to h).selective trimming of acrylic portion was done to allow eruption of posterior teeth to eliminate the excessive curve of Spee in lower arch. The activator successfully resolved the problem of the retrognathicmandible with favourable mandibular growth. After achieving the functional correction of skeletal discrepancy, the full-fixed orthodontic appliance (022 MBT) along with inclined plane was put in place for 1 year to stabilize the occlusion without extraction(fig 3- a to h). Once the occlusion was stabilized with good posterior interdigitation, fixed appliances were removed and patient was kept under retention. Since the patient was in growing phase, along with upper Hawleys plate with inclined plane, night time wear of activator was advocated. 181
TREATMENT RESULTS At the end of the treatment the patient had good activator in correcting a class II malocclusion in this patient include : functional, mutually protected occlusion with canine Stimulation of the mandibular growth. 5,6,7,8,9,13 and molar in Angles class I relationship, normal Redirection of the anterior and overjet and overbite (fig 4-d,e,f,g,h) and good facial verticaldentoalveolar growth of maxilla. 6,10,11 proportions(fig 4-a,b,c, table-4). Redirection of the anterior and Superimposing the pre and post-treatment lateral verticaldentoalveolar growth of mandible. 5,10,12 cephalograms (fig. 5) demonstrated a considerable Remodelling changes in TMJ. 13 downward and forward growth of mandible reducing CONCLUSION ANB angle to 2 from 6.Mandibular base length It is generally agreed that functional appliances can be increased from 76 mm to 85 mm(table-3). DISCUSSION Functional appliances are effective in treating skeletal used successfully to treat skeletal class II malocclusions in growing and cooperative patients. The ideal case for such treatment is: class II malocclusion, particularly in cases with Class II division I malocclusion withretrognathic retrognathic mandible functional appliances are of mandible Low to average mandibular plane angle greatest clinical benefit in actively growing patients Upright or linguallytipped lower incisors. with good compliance.in this case,the muscular force generated by the forward mandibular positioning was transferred to the maxillary and the mandibular teeth through the acrylic body and labial bow. These forces which were transmitted through the teeth to the periosteum and bone were responsible in producing a restraining effect on the forward growth of maxilla, The activator can solve many problems that become more severe if left untreated.the Activator cannot create a large mandible from a small one, but it can help the patient achieve the optimal size consistent with morphogenetic pattern 14. The restoration of the normal function is a major contribution to improvement in the morphofunctional interrelationship. while stimulating the mandibular growth and causing maxilla mandibular dentoalveolar adaptation. The major effects of the activator treatment in this case has been due to increase in condylar growth and in mandibular base length. The combination of these effects resulted in the permanent anterior displacement of mandible. The activator also had an influence on dentition. By inhibiting the maxillary dentoalveolar vertical growth and encouraging the mandibular Both skeletal and dentoalveolar changes has been achieved by activator therapy.due to favourable growth and good compliance, his facial profile became orthognathic with treatment. The overbite decreased because of molar extrusion and inhibition of incisor eruption which level the curve of Spee. The uprighting of the upper incisors also helped to reduce the overjet. Further non-extraction fixed orthodontic treatment for proper interdigitation of the dentoalveolar mesial and vertical development, the dentition will also help to maintain the stability of the activator resolved the class II malocclusion to class I satisfactory results achieved in this type of cases. malocclusion. The possible mechanisms for the 182
LEGENDS: Figure 1: Pre Treatment Photographs Figure 2 : Post functional correction 183
Figure 3 : fixed appliances in situ Figure 4 : Post Treatment Photographs Figure 5 : Pre Treatment and Post treatment lateral cephalogram Super Imposition 184
TABLE 1 CEPHALOMETRIC DATA MEAN PRE TREATMENT POST TREATMENT SNA 82 ± 2 74 73 0 SNB 80 ± 2 68 71 0 ANB 2 6 2 0 U1-NA 22 44 25 U1-NA 4mm 11mm 6mm L1-NB 25 18 0 25 L1-NB 4mm 6mm 5mm Interincisal Angle 130 114 115 GoGn-SN 32 29 31 Occ-SN 14 18 22 L1-APog 1.2mm ± 1.4mm -1mm 3 mm FMA 25 19 22 0 IMPA 90 93 98 FMIA 65 66 60 NA-APg -8-10 5 0 NPg-AB -9-0 -12-4 NPg-FH 82-95 84 96 Y-Axis 53-66 60 60 185
Table 2-CEPHALOMETRIC ANALYSIS Mc NAMARA ANALYSIS MEAN PRETREATMENT POST TREATMENT MAXILLA TO CRANIAL BASE A) Nasolabial angle 102±8 100 108 A) Cant of upper lip Female: 10 0 Male: A) Point A to N- perpendicular 0-1 mm -3 mm -6 mm MAXILLA TO MANDIBLE ANTEROPOSTERIOR A) Maxillary length (Co-A) 90 mm 96 mm A) Mandibular length (Co-Gn) 109 mm 121 mm A) Maxilla mandibular differential Small:20-23 19 mm 25 mm Medium 27-30 Large:30-33 VERTICAL A) Lower AFH (ANS-Me) 62 mm 71 M B) Mandibular plane angle (FH-Go-Me) 22±4 19 22 C) Facial axis angle (Ptm-Gn-Ba-N perpendicular) 0±3.5mm -4-5 MANDIBLE TO CRANIAL BASE Pog to N perpendicular Small: Medium: -10 mm -12 mm Large: DENTITION A) Maxillary incisor to point A 4-6mm 7 mm 5 mm A) Mandibular incisor to A-Pog 1-3mm -2 mm 3 mm 186
Table 3-Rakosi s Analysis ANALYSIS OF FACIAL SKELETON MEASUREMENT MEAN PRE-TREATMENT POST-TREATMENT SADDLE ANGLE 123 +5 130 130 ARTICULAR ANGLE 143 +6 146 146 GONIAL ANGLE 128+ 7 119 121 U- GONIAL ANGLE 52-55 51 mm 51 mm L GONIAL ANGLE 72 75 68 mm 70 mm POSTERIOR FACE HEIGHT 76 mm 85 mm ANTERIOR FACE HEIGHT 117 v 131 mm JARABACK S RATIO 62-65% 64.95 % 64.88 % ANTERIOR CRANIAL BASE LENGTH 71 mm 73 mm 78 mm POSTERIOR CRANIAL BASE LENGTH 32-35 mm 39 mm 44 mm 187
ANALYSIS OF THE JAW BASES SNA ANGLE 81 74 73 SNB ANGLE 79 68 71 ANB ANGLE 2 6 2 BASAL PLANE ANGLE 25 21 23 INCLINATION ANGLE (Pn TO ANS-PNS) 85 81 81 REFERENCES 1. Bishara S E, Ziaja RR. Functional appliance : A review, American Journal of Orthodontics and DentofacialOrthopedics 95: 250 258, 1989 2. Tulloch FC, Phillips C, Koch G, Proffit WR. The effect of early intervention on skeletal pattern in Class II malocclusion: A randomized clinical trial. American Journal of Orthodontics and DentofacialOrthopedics l l1:391-400,1997 3. Barton S, Paul AC. Predicting functional appliance treatment outcome in class II malocclusions-review. American Journal of Orthodontics and DentofacialOrthopedics112: 282 286, 1998 4. Hassel B, Farman A: Skeletal maturation evaluation using cervical vertebrae. American Journal of Orthodontics and DentofacialOrthopedics 107:58-66, 1995 5. Harvold E P, Vargervik K, Morphogenetic response to activator treatment. American Journal of Orthodontics and DentofacialOrthopedics 60: 478 490, 1971. 6. Basciftci F A, Uysal T, Büyükerkmen A, Sarı Z, The effects of activator treatment on the craniofacial structures of Class II division 1 patients. European Journal of Orthodontics 25: 87 93, 2003. 7. Webster T, Harkness M, HerbisonP, Associations between changes in selected facial dimensions and the outcome of orthodontic treatment. American Journal of Orthodontics and DentofacialOrthopedics 110: 46 53, 1996. 8. Ruf S, Baltromejus S, PancherzH. Effective condylar growth and chin position changes in activator treatment: a cephalometricroentgenographic study. Angle Orthodontist 71: 4 11, 2001. 9. Jakobsson S O,Cephalometric evaluation of treatment effect on Class II, division I malocclusions. American Journal of Orthodontics 53: 446 457, 1967. 188
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