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 Table of Contents  
CLINICAL ARTICLE
Year : 2013  |  Volume : 3  |  Issue : 1  |  Page : 31-41

Twenty -year post-treatment assessment of class II division 1 malocclusion treated with non-extraction approach


Smile Care, Bandra (West), Mumbai, India

Date of Web Publication24-Apr-2013

Correspondence Address:
Ashok Karad
Smile Care, 1/C 3-3, Sujata Niwas, S. V. Road, Bandra (West), Mumbai-400 050
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2321-1407.111139

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  Abstract 

Several treatment strategies exist to deal with class II division 1 malocclusions depending upon the configuration of the malocclusion and the age of the patient. The results produced by one or a discretionary combination of these treatment modalities can only be considered satisfactory if they remain stable, making long-term stability a main objective of orthodontic treatment. To achieve long-term stability, several different treatment techniques and philosophies have been recommended; however, despite many efforts to achieve this goal, a definitive treatment protocol is still lacking.
This article describes twenty-year post-treatment assessment of a class II division 1 malocclusion case, treated in the late mixed dentition stage, with the non-extraction treatment approach - molar-inserted headgear along with a fixed appliance therapy.

Keywords: Class II division 1, differential growth, long-term stability, molar-inserted headgear, non-extraction treatment


How to cite this article:
Karad A, Dhanjani V, Bagul V. Twenty -year post-treatment assessment of class II division 1 malocclusion treated with non-extraction approach. APOS Trends Orthod 2013;3:31-41

How to cite this URL:
Karad A, Dhanjani V, Bagul V. Twenty -year post-treatment assessment of class II division 1 malocclusion treated with non-extraction approach. APOS Trends Orthod [serial online] 2013 [cited 2018 Jun 21];3:31-41. Available from: http://www.apospublications.com/text.asp?2013/3/1/31/111139


  Introduction Top


Class II division 1 is a broad term designated to a set of various abnormalities that could be either simple or most complex. It is not a single clinical entity and is often associated with significant skeletal and dental imbalances expressed as sagittal discrepancies. There are several treatment strategies to deal with class II division 1 malocclusion depending upon the configuration of the malocclusion and the age of the patient. The treatment results produced by one or a discretionary combination of the various available treatment strategies can only be considered satisfactory if they remain stable for long duration. To achieve long-term stability, several different approaches have been recommended including overcorrection of the posterior occlusion, and overbite and overjet relationships. Achieving maximum occlusal intercuspation, maintaining original archform, and positioning the mandibular incisors upright over basal bone have also been considered as methods to minimize post-retention relapse. Following orthodontic treatment, it has been further suggested that the teeth should be retained long enough to allow bone and adjacent soft tissues to re-organize. [1],[2] Addressing various elements of functional occlusion as one of the finishing goals has been recommended to improve long-term post-treatment stability. [3] This approach also emphasizes that the detailed finished occlusion is a key factor in determining optimal joint function following orthodontic treatment. It should be recognized that craniofacial growth is important not only during the course of treatment but post-treatment as well. This article describes twenty-year post-treatment assessment of a class II division 1 malocclusion case treated with the non-extraction treatment approach - molar-inserted headgear along with fixed appliance therapy.

Diagnosis and etiology

The patient was 11 years 8 months old when he reported to the clinic, with a chief complaint of "protruding upper jaw teeth." Clinically, he had a convex profile, incompetent lips, and deep mentolabial sulcus [Figure 1]. Intra-orally, he had proclined incisors and deep overbite. The maxillary canines were labially placed and in a class II relationship. The molars were in an end-on relationship bilaterally, and the presence of the maxillary second deciduous molars were noted [Figure 2]. The pre-treatment study models demonstrated maxillary anterior proclination of 7.1 mm, 10.5 mm of overjet, and 7.1 mm of overbite. The class II molar discrepancy was 4.4 mm on the right side and 3.83 mm on the left, while the class II canines had 5.19 mm and 5.80 mm of class II discrepancies on the right and left sides, respectively [Figure 3], [Table 1]
Table 1: Model analyses

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Figure 1: Pre-treatment extraoral photographs of 11 years 8 months old patient showing convex profile, incompetent lips, and deep mentolabial sulcus. Source: Clinical Orthodontics: Current Concepts, Goals and Mechanics by Dr. Ashok Karad (ISBN: 9788131221914), published by Reed Elsevier India Pvt. Ltd

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Figure 2: Pre-treatment intraoral photographs showing increased overjet and overbite, labially placed maxillary canines, class II canine and molar relationships. Source: Clinical Orthodontics: Current Concepts, Goals and Mechanics by Dr. Ashok Karad (ISBN: 9788131221914), published by Reed Elsevier India Pvt. Ltd

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Figure 3: Pre-treatment study models

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The pre-treatment cephalometric analysis showed maxillary prognathism [SNA 84°], mandibular deficiency [SNB 76°], indicating a skeletal class II malocclusion [ANB 8°, WITS 10 mm]. The maxillary incisors were proclined [U1-SN 111°], the mandibular incisors were upright [IMPA 92°], with an average mandibular plane angle [FMA 23°] [Figure 4], [Table 2].
Table 2: Cephalometric Analysis

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Figure 4: Pre-treatment lateral cephalometric tracing

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Functional assessment performed during the clinical examination revealed that the lower lip was trapped between maxillary and mandibular incisors, and its posture and function in the same area along with hyperactive mentalis muscle function led to progressive deforming activity in the dentition.

Treatment objectives

Once patient's diagnostic information is synthesized into dental, skeletal, functional, and soft-tissue profile, the orthodontic treatment goals should be clearly defined. The diagnostic information, especially the clinical examination, must reveal what the patient desires to gain from the treatment, and it must be included in the treatment goals and in the final treatment plan.

The Treatment Objectives were:

  • To achieve normal skeletal relationships by restraining maxillary growth and allowing the mandible to grow normally.
  • To achieve optimal facial esthetics by reducing the overjet, overbite, and proper interincisal relationship to establish normal lower lip posture and naso-labial angle.
  • To achieve normal static occlusal relationships by proper alignment of maxillary and mandibular teeth, well-coordinated archforms, leveled marginal ridges, proper position of contact points, and maximum intercuspation of posterior teeth.
  • To achieve dynamic occlusal relationships by establishing a mutually protected occlusal scheme.
  • To achieve normal orofacial function by making it possible for the patient to adequately close the lips, establishing proper lip posture and function. Preservation of normal tongue function and teeth-together swallowing pattern should be the integral parts of treatment objectives.
  • To achieve optimal periodontal health, which includes the preservation and minimum treatment-induced deterioration of hard and soft tissues of the periodontal apparatus.
  • To achieve long-term post-treatment stability by finishing the case to highest possible standards with appropriate treatment mechanics followed by individualized retention protocol.


[Table 3] demonstrates various parameters, problem list, and the treatment objectives for this patient.
Table 3: Treatment objectives

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Treatment alternatives

It requires a great deal of flexibility on part of the clinician to carefully explore and examine several treatment possibilities to formulate a successful treatment plan. It is important to make sure that the final treatment option is carefully assessed and fits with the overall treatment objectives.

Several treatment options were explored and evaluated including waiting until all growth was completed and determining whether the malocclusion could be camouflaged by orthodontic treatment involving extractions in the maxillary arch; the use of functional appliances with the intent to restrain maxillary growth and to stimulate mandibular growth, which was ruled out as the clinical test involving posturing the mandible forward did not produce pleasing profile. Considering the patient's problem list and overall treatment objectives, it was decided to use molar-inserted headgear to restrain the growth of the maxilla, while simultaneously conserving the 'E' space and allowing the mandible to grow normally as a part of non-extraction treatment approach.

The use of extraoral appliances in the early and late mixed dentition stage produces an orthopedic effect that is important for patients with maxillary prognathism. [4] The leeway space can provide adequate space to align and accommodate crowded teeth in majority of patients. [5]

Treatment progress

The maxillary arch was bonded with 0.018'' slot Vari simplex Discipline appliance, and 0.017 x 0.025'' multistranded rectangular wire was placed for the initial torque control, with no appliance in the mandibular arch for the initial six months [Figure 5]. Molar-inserted combination pull headgear was given to inhibit growth in the mid-face region and allow the normal growth of the mandible. To produce skeletal change and to minimize dental effects, the extra oral force of greater magnitude, in the range of 400 - 450 gms per side, was used, and was worn at least 13 -14 hrs per day. This was preceded by alignment of maxillary arch and an effective utilization of 'E' spaces to retract maxillary incisors. Omega loops were incorporated in the upper archwire just mesial to the first molar tubes, and were tied back to the molars with steel ligatures to make the entire upper arch into a single unit [Figure 6]. After six months, the mandibular arch was bonded, followed by the sequential use of archwires, in both arches to establish good occlusal relationships.
Figure 5: Initial stage of treatment demonstrating the use of 0.017 X 0.025 multistranded stainless steel wire for initial torque control

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Figure 6: Mid-treatment intraoral photographs exhibiting an improvement in occlusal relationships

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Just prior to the placement of finishing arch wires (0.017" x 0.025" SS), the maxillary and mandibular second molars erupted, and were subsequently banded and aligned. During the finishing stage, both maxillary and mandibular arch wires were ligated with steel ligatures, and most of the occlusal parameters like normal overbite and overjet relationships, coincident midlines, proper torque and angulation of individual teeth, coordinated arch forms, class I molars and canine relationships, flat curve of Spee, etc. were achieved [Figure 7]. Mandibular excursions were evaluated to make sure that there was proper anterior guidance during protrusive movement with no posterior interferences, and that there was a cuspid rise on both right and left lateral excursions with no balancing interferences [Figure 8]. As the maxillary and mandibular bicuspids on either side were held away from each other with the rigid finishing archwires, the archwires were cut distal to canines, and vertical elastics were used to achieve maximum intercuspation [Figure 9].
Figure 7: Finishing stage of treatment, coordinated and compatible archforms. Source: Clinical Orthodontics: Current Concepts, Goals and Mechanics by Dr. Ashok Karad (ISBN: 9788131221914), published by Reed Elsevier India Pvt. Ltd

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Figure 8: Mandibular excursions: Protrusive, right lateral, and left lateral

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Figure 9: Vertical settling of posterior teeth to achieve maximum intercuspation. Source: Clinical Orthodontics: Current Concepts, Goals and Mechanics by Dr. Ashok Karad (ISBN: 9788131221914), published by Reed Elsevier India Pvt. Ltd

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Pre-debonding evaluation was carried out to check that the treatment objectives defined at the beginning of treatment were carefully assessed and matched [Figure 10] and [Figure 11].
Figure 10: Pre-debonding evaluation to check if all occlusal objectives have been achieved

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Figure 11: Face-bow record to orient and transfer the maxillary cast to the articulator, and subsequently to check CO-CR discrepancy

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Once all the treatment objectives were achieved, the orthodontic appliances were removed, and maxillary and mandibular Essix retainers were delivered [Figure 12],[Figure 13],[Figure 14],[Figure 15],[Figure 16].
Figure 12: Post-treatment intraoral photographs showing normal occlusal relationships. Source: Clinical Orthodontics: Current Concepts, Goals and Mechanics by Dr. Ashok Karad (ISBN: 9788131221914), published by Reed Elsevier India Pvt. Ltd

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Figure 13: Post-treatment extraoral photographs demonstrating improvement in facial profile, lip competence, and pleasing esthetics. Source: Clinical Orthodontics: Current Concepts, Goals and Mechanics by Dr. Ashok Karad (ISBN: 9788131221914), published by Reed Elsevier India Pvt. Ltd

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Figure 14: : Post-treatment lateral cephalometric tracing

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Figure 15: Pre-and post-treatment lateral cephalometric superimpositions

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Figure 16: Retention phase. Essix retainers in place

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The maxillary and mandibular archwire sequences and individualized forces employed during the course of treatment are shown in [Table 4], [Table 5], and [Table 6], respectively.
Table 4: Maxillary arch wire sequence

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Table 5: Mandibular arch wire sequence

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Table 6: Individualized forces

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Treatment results

A well-balanced facial profile was achieved at the conclusion of treatment. Class I molar relationships were achieved from the pre-treatment class II molar discrepancy of 4.4 mm on the right side and 3.83 mm on the left side. Bilateral class I canine relationships were obtained from the pre-treatment class II canine discrepancies of 5.19 mm and 5.8 mm on the right and left sides, respectively [Figure 12] and [Figure 13].

The pre-treatment overjet of 10.5 mm was reduced to 2.5 mm post-treatment, while an overbite of 1.81 mm was obtained from the pre-treatment value of 7.1 mm. The pre-treatment maxillary incisor proclination of 7.1 mm, as measured on the model, was reduced to 4.37 mm post-treatment. Coincident maxillary and mandibular dental midlines were achieved from the pre-treatment midline discrepancy of 2.6 mm (the mandibular midline was shifted to the patient's left side).

The maxillary and mandibular archforms were symmetrical and well-coordinated post-treatment. The normal lip seal, proper lower lip posture, and teeth-together swallowing pattern without hyperactivity of perioral musculature were achieved at the conclusion of treatment.

The cephalometric analysis demonstrated that there was significant forward growth restriction in the maxillary complex and favorable changes in the mandibular component, resulting in an improvement in the maxillo-mandibular relationship [Figure 14], [Table 2]. The maxillary incisors were uprighted and retracted over their basal bone, with mandibular incisors showing mild advancement post-treatment. The mandibular plane angle was maintained post-treatment. Because of dento-alveolar and skeletal changes, the overjet and overbite relationships were significantly reduced with the achievement of class I molar relationship. These changes significantly contributed to a well-balanced soft-tissue profile [Figure 15].

The patient was satisfied with both the facial and dental treatment outcomes. His parents also reported that he became more confident and socially outgoing.

The active treatment of 22 months was followed by 24 months of retention period.

Long-term follow-up

Orthodontics has witnessed scientific and technological advances over the last few decades, and many treatment techniques and philosophies have been changed to achieve treatment goals. Long-term stability is a main objective of orthodontic treatment; however, despite the many efforts to achieve this goal, a definitive treatment protocol is still lacking. To identify those treatment techniques and philosophies in alignment with the objective of long-term stability, long-term critical evaluation of cases is essential.

Patient records, obtained twenty years post-treatment, demonstrate that the facial profile and improvements in the smile characteristics have been well maintained [Figure 17]. The molar relationship on the right side was class I; however, the left side molar relationship was end-on, with a relapse of 1.78 mm. The right side canine relationship was stable, and the left side exhibited end-on canine relationship, demonstrating 2.4 mm of relapse [Figure 18]. Twenty-year post-treatment, the overjet was increased by 1.5 mm and the overbite deepened by 1.54 mm. The proclination of maxillary incisors, as measured on the models, showed 0.75 mm of increase from the post-treatment value. The mandibular midline was shifted to the left side by 0.79 mm. During the twenty-year post-treatment period, the curve of Spee was deepened by 2.18 mm. The shape and the form of arches were fairly well maintained. The only parameter which did not exist pretreatment but was evident twenty-year post-treatment was the presence of 1.39 mm of mandibular anterior crowding due to disto-labial rotation of the left central incisor [Figure 19],[Figure 20],[Figure 21], [Table 1] and [Table 2].
Figure 17: Twenty-year post-treatment extraoral photographs

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Figure 18: Twenty-year post-treatment intraoral photographs demonstrating right side class I Interarch relationship, left side endon relationship, and the mandibular midline shift to the left side. The maxillary and mandibular archforms are well maintained. The mandibular anterior segment shows distolabial rotation of the left central incisor

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Figure 19: Twenty-year post-treatment lateral cephalometric tracing

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Figure 20: Pre-treatment, post-treatment and twenty-year posttreatment lateral cephalometric superimpositions

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Figure 21: Twenty-year post-treatment study models

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Figure 22: Growth increments

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Differential growth

The posterior portion of the maxilla carries the maxillary molars downward, making the mandibular plane steeper, unless condyles grow an equal amount. Therefore, the relationship between two basic growth increments - condylar growth and molar growth, determines the rotation of the mandible, the translation of the mandible, the forward movement of the chin, and the vertical movement of the chin. [6] During the treatment period, the condyles grew vertically by 9 mm and horizontally by 5 mm, while the vertical palatal displacement was 4 mm, vertical maxillary molar movement was 0 mm, and vertical mandibular molar growth was 2 mm (4 + 0 + 2 = 6 mm).

The post-treatment growth was characterized by 7 mm and 2 mm of vertical and horizontal condylar growth, respectively, while the total vertical molar growth was as a result of the vertical palatal displacement of 1.5 mm, vertical maxillary molar growth of 2 mm, and the vertical mandibular molar growth of 4 mm (1.5 + 2 + 4 = 7.5 mm).

Therefore, combined growth (during treatment and post-treatment period) is characterized by vertical and horizontal condylar growth of 16 mm and 7 mm, respectively, while the vertical palatal displacement was 5.5 mm, vertical maxillary molar growth of 2 mm, and vertical mandibular growth of 6 mm (5.5 + 2 + 6 = 13.5 mm) [Figure 22].

This resulted in the displacement of the chin anteriorly by 5 mm and vertically by 13 mm, and the occlusal plane rotation by 8 degrees and mandibular plane rotation by just 1 degree.


  Discussion Top


The dental and skeletal treatment changes, combined with a differential growth of the facial skeleton, contributed to a well-balanced facial profile at the end of treatment. There was significant forward growth restriction in the maxillary complex with desired changes in the mandibular component, leading to improvement in the basal bone relationship. The maxillary incisors were uprighted and retracted in their basal bones with relatively less changes in the mandibular dentition. There was significant reduction in overjet and overbite relationships as a result of dento-alveolar and skeletal changes during treatment.

In the post-treatment period, most of the maxillary complex changes were consequent to normal growth and development. The maxilla resumed its natural growth pattern without exhibiting its contribution to the relapse of the sagittal discrepancy.

Growth that usually takes place in the post-treatment period is characterized by a mandibular counter-clockwise rotation in response to the vertical redirection of the condylar growth, [7] as also observed by a decrease in angles SN-GoGn and SN-PP, though significantly smaller amounts considering the post-treatment period of 20 years. It has been observed that, in individuals with more pronounced forward-growth rotation of the jaws, there is a natural tendency for the molar relationship to become more class II with time. [8] As a consequence of normal growth changes, the posterior teeth in both arches tend to follow the growth rotations of the jaws. Therefore, with forward-growth rotation, the posterior teeth become more mesially inclined in the maxilla and more distally inclined or upright in the mandible. [9]

The maxillary incisors, despite their extensive uprighting and retraction, exhibited good stability even 20 years post-treatment. It has been shown that, the more the mandibular incisors are labially tipped during treatment, the less their stability in the post-treatment period. [10] However, in this case, the treatment-induced mild labial inclination of the mandibular incisors continued similar trend during post-treatment period. This may be attributed to the elimination of lower lip trap and the hyperactive mentalis muscle activity post-treatment.

The maxillo-mandibular relationship was stable, as there was just a one degree of increase in ANB angle over a twenty-year period.

One of the classic theorems of stability tells the clinician to maintain the original archform. [11] Research has shown that the increase in intercanine width during treatment is associated with post-treatment relapse. [12] However, in this case, the maxillary intercanine width was increased by 1.5 mm during treatment and by 1 mm during the post-treatment period. However, the mandibular intercanine width was decreased by 1 mm during treatment and demonstrated similar trend during the post-treatment period [Table 7]. In the maxillary arch, intermolar width was maintained during treatment period, and increased by 1.5 mm post-treatment. The intermolar width in the mandibular arch was almost maintained during treatment phase and slightly increased post-treatment.
Table 7: Arch form analyses

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Maxillary arch length was decreased during treatment, due to uprighting and retraction of incisors. The mandibular arch length was maintained during the course of treatment. However, the arch lengths decreased in the post-retention stage. These results agree with those of Glen et al. [13] , who observed a post-retention arch length decrease in 96% of non-extraction cases. This also supports the concept of decrease in arch length consequent to the anterior component of force that tends to cause a mesial drift of the posterior teeth with time. [14]

In this case, the mandibular incisors were proclined during treatment and demonstrated similar trend in post-treatment period as well. This shows that final mandibular incisor inclination and linear protrusion do not influence incisor position relapse; this corroborates the findings of Schulhof et al. [15] These results also support the statement that no cephalometric data are useful for establishing a prognosis regarding incisor position relapse. [16],[17] In this patient, the mandibular incisors, despite their cephalometric protrusion during treatment, did not show signs of relapse during post-retention phase. In author's opinion, it is not the cephalometric mandibular incisor protrusion but its effect on the balance of the overlying soft tissues is critical in incisor stability. If the cephalometric incisor protrusion is not associated with strained overlying soft tissues, there does not seem to be any factor that could contribute to incisor position relapse.

The post-treatment mandibular anterior crowding, though mild, was not as a result of relapse; rather, it was a new entity observed during the long-term assessment. This could be as a result of continuing physiologic changes. This supports the observations that, mandibular anterior crowding during the post-treatment phase is a continuing phenomenon well into the 20-to-40 years age bracket and likely beyond. [18],[19] Post-treatment increased crowding of mandibular incisors in the absence of crowding or beyond any degree of crowding that might have been present pre-treatment is associated with changes related to maturation.

The nose and chin [mandible] appear to maintain growth longer than the other extremities; therefore, the lips appear to become retrusive in relation to the nose and chin over the long-term according to the soft tissue analyses. [20]


  Conclusions Top


The overall skeletal, dento-alveolar and facial changes obtained with non-extraction fixed appliance therapy, combined with molar-inserted combination pull headgear, in the treatment of class II division 1 malocclusion in late mixed dentition were excellent. Considering the long-term assessment of twenty years post-treatment, the observed unfavorable dento-alveolar changes in the post-treatment period were minimal as the long-term change is a biological occurrence, during and following treatment, as a normal event of maturation. To improve long-term stability, the clinician should recognize the continuing effects of dento-facial growth - in particular, residual growth - and its resultant favorable or unfavorable effects on the occlusal relationships and the face.

These changes did not have any adverse effect on facial esthetics, stomatognathic function, the periodontal health, and the level of patient satisfaction; and the treatment results were demonstrated to be stable on a long-term basis.

 
  References Top

1.Reitan K. Principles of retention and avoidance of post treatment relapse. Am J Orthod 1969;55:776-90.  Back to cited text no. 1
    
2.Reitan K. clinical and histological observations on tooth movement during and after orthodontic treatment. Am J Orthod 1967;53:721-45.  Back to cited text no. 2
    
3.Karad A. Excellence in finishing: current concepts, goals and mechanics. J Indian Orthod Soc 2006;39:126-8.   Back to cited text no. 3
    
4.Wieslander L. early or late cervical traction therapy of class II malocclusions in the mixed dentition. Am J Orthod 1975;67:432-9.  Back to cited text no. 4
    
5.Arnold S. Analysis of leeway space in the mixed dentition. Master's thesis, Boston: Boston University; 1991.  Back to cited text no. 5
    
6.Schudy FF. The rotation of the mandible resulting from growth: Its implications in orthodontic treatment. Angle Orthod 1965;35:36-50.  Back to cited text no. 6
    
7.Schudy G. Posttreatment craniofacial growth: Its implications in orthodontic treatment. Am J Orthod 1974;65:39-57.  Back to cited text no. 7
    
8.Uhde MD, Sadowsky C, Begole EA. Long term stability of dental relationships after orthodontic treatment. Angle Orthod 1983;53:240-52.  Back to cited text no. 8
    
9.Bjork A, Skieller V. Facial development and tooth eruption. Am J Orthod 1972;62:339-83.  Back to cited text no. 9
    
10.Elms T, Buschang P, Alexander R. long-term stability of Class II div I nonextraction cervical face-bow therapy: II- cephalometric analysis. Am J Orthod Dentofac Orthop 1996;109:386-92.  Back to cited text no. 10
    
11.Joondeph DR, Riedel RA. Retention. In: Greater TM, Swain BF, editors. Orthodontics: Principal and techniques. St Louis: Mosby; 1985. p. 857-898.  Back to cited text no. 11
    
12.Artun J, Garol JD, Little RM. Long-term stability of mandibular incisors following successful treatment of Class II div I malocclusions. Angle Orthod 1996;66:229-38.  Back to cited text no. 12
    
13.Glenn G, Sinclair P, Alexander R. nonextraction orthodontic therapy: post treatment dental and skeletal stability. Am J Orthod Dentofac Orthop 1987;92:321-8.  Back to cited text no. 13
    
14.Thilander B. Biological basis for orthodontic relapse. Semin Orthod 2000;6:195-205.  Back to cited text no. 14
    
15.Schulhof RJ, Allen RW, Walters RD, Dreskin M. the mandibular dental arch: Part I, lower incisor position. Angle Orthod 1977;47:280-7.  Back to cited text no. 15
    
16.Shields TE, Little RM, Chapko MK. Stability and relapse of mandibular anterior alignment: a cephalometric appraisal of first premolar extraction cases treated by traditional edgewise orthodontics. Am J Orthod 1985;87:27-38.  Back to cited text no. 16
    
17.Paquette DE, Beattie JR, Johnston LE Jr. A long-term comparison of non extraction and premolar extraction edgewise therapy in "borderline" Class II patients. Am J Orthod Dentofac Orthop 1992;102:1-14.  Back to cited text no. 17
    
18.McReynolds D, Little R. Mandibular second premolar extraction: Post retention evaluation of stability and relapse. Angle Orthod 1991;61:133-44.  Back to cited text no. 18
    
19.Little R, Riedel R, Engst E. Serial extraction of first premolars: Post retention evaluation of stability and relapse. Angle Orthod 1990;60:255-262.  Back to cited text no. 19
    
20.Rossouw PE. Retention and stability: A perspective. In: Karad A, editor. Clinical Orthodontics: Current concepts, goals and mechanics. New Delhi: Elsevier; 2010. p. 399-426.  Back to cited text no. 20
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19], [Figure 20], [Figure 21], [Figure 22]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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