One Phase Treatment of Adolescent Class II Malocclusion Using Twin-Block Appliance and Preadjusted Edgewise Appliance—A Case Report

Abstract

This case report was presented in the Indian Board of Orthodontics examination under category II in September 2020. It demonstrates the one-phase treatment of a skeletal class II malocclusion in a 11 year-4-month old female using a combination of functional and fixed appliance therapy. The treatment summary along with various supporting records are reprinted here with minimal editing and reformatting so as to reproduce the actual documents submitted to the board.

Introduction

Class II malocclusion comprises a broad array of specific skeletal, dental, and soft tissue features. It ranks second in distribution and prevalence among Angle’s classes of malocclusion. ¹ However, it is the most frequently encountered and treated malocclusion in orthodontic practice.

Mandibular deficiency, rather than maxillary excess, is reported to be the most common cause of skeletal class II malocclusion. ² In such cases, growth modulation using functional jaw orthopedics has been the widely accepted treatment modality when sufficient favorable growth remains. ³ The choice of a particular appliance among the plethora of functional appliances depends on a case-based analysis and the clinician’s choice. The Twin-block appliance is found to be the most preferred removable functional appliance.

The case report presented below illustrates 1-phase treatment of a 11-year-old female with a skeletal class II malocclusion using the standard twin-block appliance followed by comprehensive fixed appliance.

Case Report

JJ, a 11 year-4-month old prepubertal female of South Indian origin in early permanent dentition stage presented with class II division 1 malocclusion on a moderate class II skeletal base attributed to mandibular deficiency with an average growth pattern. The mentolabial sulcus was deep with an everted lower lip and presence of lip trap. There was significant proclination of upper incisors and mild proclination of lower incisors, having an overjet of 8 mm and 60% overbite. The lower anterior were supraerupted with an accentuated curve of Spee. There was midline diastema of 1 mm in the upper arch with mesiopalatal rotation of 16 and crowding of 3 mm in the lower arch. She was in Cervical Vertebrae Maturation Index (CVMI) stage 3 with a positive clinical visualized treatment objective (VTO).

A growth modification treatment was planned using twin-block appliance for the correction of mandibular retrusion followed by nonextraction comprehensive orthodontic treatment for establishing occlusion. Appreciable improvement was achieved with facial esthetics and a stable buccal occlusion was established with bilateral class I molar and canine relation, normal overjet, and overbite with a class I incisor relation. Peer Assessment Rating (PAR) Index scores improved from 30 to 2 at the end of treatment with a change of 93.3%.

Section I: Pretreatment Assessment Details

Initials: JJ

Gender: Female

Date of birth: July 5, 2007

Age at start of treatment: 11 years 4 months and 22 days

Patient’s complaint: “Top front teeth are sticking out”

No relevant medical, dental, and family history were revealed.

Clinical Examination: Extraoral Features

The pretreatment extraoral photographs are given in Figure 1.

Figure 1.

Source: Patient records.

Skeletal Assessment

Anteroposterior: Class II skeletal pattern with a convex facial profile and posterior divergence. Soft tissue pogonion was retrusive relative to zero meridian.

Vertical: Average Frankfort-mandibular plane angle (FMA). There was 4.5-mm upper incisor visibility at rest and full incisor exposure (100%) on smile.

Transverse: Mesoprosopic facial form with acceptable facial symmetry and balance on frontal examination.

Soft Tissue Assessment

Upper lip was normotonic whereas lower lip was hypertonic and everted. There was markedly negative lip step with the upper lip in line while the lower lip 3 mm short of Ricketts’ E line. Lips were potentially competent at rest with an inter-labial gap of 5 mm. Anterior oral seal was created by lip-to-lip contact with perioral hyperactivity. The mentolabial sulcus was deep with presence of lip trap. Nasolabial angle was average. Smile arc was nearly consonant.

TMJ Assessment

No signs or symptoms of TMD.

Clinical Examination: Intraoral Features

The pretreatment intraoral photographs are given in Figure 2.

Figure 2.

Source: Patient records.

Soft tissues: No abnormality detected.

Oral hygiene: Fair

Erupted teeth present:

General dental condition: No restorations were noted. Few enamel decalcifications were observed.

Crowding/Spacing

Maxillary arch: U-shaped arch form. Symmetrical with proclination and spacing of 1 mm between the central incisors (midline diastema). Buccal segments are aligned with mesiopalatal rotation of 16.

Mandibular arch: U-shaped arch form. Symmetrical with mild crowding of the anterior segment. Buccal segments are aligned.

Occlusal Features

Incisor relationship: Class II division 1

Overjet (mm): 8 mm

Overbite: 4 mm (60%)

Centerlines: Upper and lower dental midlines were coincident with facial midline

Left and right buccal: Molars in half unit class II (End on by 3.5 mm)

egment relationship: Canine relation was end-on

Crossbites: None

Displacements: Lingual displacement of 42

Other occlusal features: Curve of Spee of 3.5 mm

Model analysis: Bolton’s analysis revealed overall mandibular tooth material excess of 0.7 mm and anterior maxillary excess of 1.3 mm. Carey’s analysis showed a space deficiency of 3 mm while the arch-perimeter analysis showed a space excess of 2 mm.

General Radiographic Examination

Pretreatment Radiographs Taken

• Lateral cephalogram on November 21, 2018 (Figure 3)

• Orthopantomogram on November 21, 2018 (Figure 4)

Figure 3.

Source: Patient records.

Figure 4.

Source: Patient records.

Relevant Radiographic Findings

The normal compliment of permanent teeth was present with no abnormalities in tooth forms as well as the surrounding structures. The lower left third molar was congenitally absent while those in the other quadrants were unerupted. The crestal bone level was normal.

Pretreatment Cephalometric Findings and Their Interpretation

The pretreatment cephalometric values are provided in Tables 1 and 2.

Skeletal: The cephalometric analysis revealed a moderate class II skeletal sagittal relationship with an Subspinale (A-point) Nasion-Supramentale (B point) (ANB) of 6.5° and Wits appraisal of +4 mm. N perpendicular to Pt. A was −1 mm indicating an orthognathic maxilla, while N perpendicular to Pog. value of −10 mm confirmed a retrognathic mandible. The effective mandibular length was also reduced at 86 mm. These reduced linear values were further confirmed by Schwarz analysis, thus suggestive of a short mandible. The Saddle angle (122°) and Articular angle (145°) were normal showing a normally positioned mandible. In addition, an average Gonial angle (129°) indicated a favorable prognosis for functional appliance. The maxilla-mandibular plane angle (25°) and Jarabak ratio of 64.2% confirmed the favorable growth pattern. CVMI was at stage 3 acceleration, with significant adolescent growth expected.

Dental: The upper incisors were moderately proclined (U1-NA = 33°, U1-SN = 116°) while the lower incisors were mildly proclined (L1-NB = 30°) with an IMPA of 101° indicating dental compensation. The interincisal angle was reduced (109°). The lower incisor edge was 2 mm ahead of the A-Pogonion reference line. The overbite (4 mm) and overjet (8 mm) were increased.

Soft tissues: The upper lip (−1 mm) and lower lip (0 mm) are mildly protrusive relative to Ricketts’ E-Line. Her nasolabial angle was average (100°).

Table 1.

Cephalometric Findings at Different Stages of Treatment.

Variable	Normal	Pretreatment	Midtreatment	Posttreatment
Sagittal Skeletal Relationship
SNA	83° ± 3°*	81°	81°	82°
SNB	80° ± 3°*	74.5°	78°	78°
ANB	3° ± 2°*	6.5°	3°	4°
Wits appraisal	1mm ± 1.5 mm*	4 mm	1 mm	2 mm
Dental-Base Relationship
Upper incisor to NA (mm/deg)	27° ± 6°/6 mm + 4 mm*	33°/6 mm	23°/4 mm	19°/3 mm
Lower incisor to NB (mm/deg)	29° ± 6°/7 mm + 6 mm*	30°/5 mm	33°/7 mm	27°/4 mm
Upper incisor to SN plane	107° ± 5°*	116°	105°	100°
Lower incisor to mandibular plane (IMPA)	99° ± 6°*	102°	103°	93.5°
Dental Relationship
Inter incisal angle	116° ± 6°*	109°	119°	131°
Lower incisor to APo line	4.5 mm ± 2 mm*	+2 mm	+7 mm	+3 mm
Overbite	2 mm	4 mm	3 mm	3 mm
Overjet	2 mm	8 mm	2.5 mm	2 mm
Vertical Skeletal Relationship
FMA	27°*	25°	26°	26.5°
SN to mandibular plane	32°*	34°	35°	27°
Maxillary mandibular plane angle	27° ± 3°	25°	25.5°	36°
Upper anterior face height	55 mm ± 3 mm*	42 mm	43 mm	43 mm
Lower anterior face height	69 mm ± 4 mm*	48 mm	50 mm	51 mm
Face height ratio	45:55	42:48	43:50	43:51
Jarabak ratio	62-65	64.2	63.4	63.4
Maxillary length—effective	89 mm ± 10 mm*	74 mm	75 mm	75 mm
Mandibular length—effective	111 mm ± 12 mm*	86 mm	91 mm	91 mm
Soft Tissues
Lower lip to Ricketts E plane	−0.5 mm*	0 mm	+2 mm	−1 mm
Nasolabial angle	96° ± 9°*	100°	90°	100°

Source: Patient records

* Kumar J. A Handbook of Cephalometric Norms for Indian Ethnic Groups—A Compilation of Published Cephalometric Studies. Indian Orthodontic Society; 1993.

Table 2.

Additional Cephalometric Analysis.

Variable	Normal		Pretreatment	Midtreatment	Posttreatment
Mandibular base extent (Go-Pg)	68 mm (8 yrs)	74 mm (11 yrs)	59 mm	62 mm	62 mm
Maxillary base extent (PNS-Pt A)	45.5 mm (8 yrs)	49.1 mm (11 yrs)	41 mm	42 mm	42 mm
Ascending ramus extent (Go-Cd)	46 mm (8 yrs)	52 mm (11 yrs)	37 mm	38 mm	38 mm
Maxillo-mandibular difference	22.3 ± 2.1 mm (12 yrs)		12 mm	16 mm	16 mm
N-Se:Mandibular base	20:21		20:19.6	20:20.4	20:20.4
Ascending ramus: Mandibular base	5:7		5:7.9	5:8.1	5:8.1
Maxillary base: Mandibular base	2:3		2:2.8	2:3	2:3
N perpendicular to Pt. A	−0.21 mm ± 3.45 mm		−1 mm	0 mm	0 mm
N perpendicular to Pog	−6.26 mm ± 4.78 mm		−10 mm	−6 mm	−7 mm
Se-N length	69.8 mm (11 yrs) (Ref: Broadbent and Bolton)		60 mm	61 mm	61 mm
S-Ar	32-35 mm		27 mm	28 mm	28 mm
Saddle angle (N-S-Ar)	123° ± 5°		122°	122°	122°
Articular angle (S-Ar-Go)	143° ± 6°		145°	145°	145°
Gonial angle (Ar-Go-Me)	128° ± 7°		127°	128°	130°
Sum of posterior angles	396° ± 6°		394°	395°	397°
Angle of inclination	85°		85°	85°	85°
Upper lip to E-line	−2 mm to −4 mm		−1 mm	−4 mm	−4 mm
Interlabial gap	2.4 mm ± 1.1 mm		2 mm	2 mm	0 mm

Source: Patient records

Diagnostic Summary

The skeletal and dental relationships confirmed a class II skeletal base malocclusion due to retrognathic mandible with a favorable growth pattern and class II molar and end-on canine relation on either side. The mentolabial sulcus was deep with an everted lower lip and presence of lip trap, and an increased overjet of 8 mm. The maxillary arch was U shaped with a mesiopalatal rotation of 16. Overbite was deep with significant upper incisor proclination. There was midline diastema of 1 mm in the upper arch and crowding of 3 mm in the lower arch. She was in CVMI stage 3 with a positive clinical VTO.

Problem List

1. Class II skeletal pattern due to retrognathic mandible, deep mentolabial sulcus, and convex profile.

2. Class II division 1 incisor relation with 8-mm overjet and class II molar relationship.

3. 60% deep bite.

4. Proclined and spaced upper incisors with mesiopalatal rotation of 16.

5. Mild crowding of the lower incisors.

6. Everted lower lip with deep mentolabial sulcus.

Aims and Objectives of Treatment

1. Maintain good oral hygiene throughout treatment.

2. Correction of the class II skeletal base relationship by mandibular growth modulation.

3. Correction of upper incisor proclination, limit the lower incisor proclination, and correct the overjet.

4. Correction of deep bite by differential eruption of the posteriors.

5. Level, align with derotation of the upper molar, and coordinate the dental arches.

6. Achieve class I molar and canine relation bilaterally.

7. Achieve class I incisor relation and a coinciding midline.

8. Achieve ideal soft tissue aesthetics and a consonant smile.

9. Retain the corrected result.

Treatment Plan

A one-phase comprehensive treatment was planned with myofunctional appliance therapy using Twin-block appliance, immediately followed by upper and lower preadjusted edgewise fixed appliance (0.022″ × 0.028″ MBT) to derotate, level, align, and detail the occlusion.

Construction bite for Twin-block was planned with a sagittal advancement of 7 mm, and vertical/interincisal opening of 2 mm, keeping in mind the freedom of movement and sufficient height for the posterior blocks of 6 mm in the premolar region and 2 to 3 mm toward the terminal molar.

Initial derotation of 16 was planned with NiTi aligning archwires using second molar as source of anchorage. In later stages (0.016″ SS and 0.018″ SS), asymmetric offset bends (toe-in) were used for final derotation and its maintenance thereafter.

Proposed retention strategy: Post Twin-Block therapy during the transition phase, an anterior inclined bite plane (AIBP) retained using ball end clasp was planned simultaneously with fixed appliance until rigid archwires with class II mechanics were to be initiated. Following debonding, bonded lingual retainers (3-3) in upper and (3-3) in lower along with upper (with AIBP) and lower wrap around retainers for night-time wear were planned.

Prognosis for stability: Considered to be good, if proper occlusal interdigitation and control of upper incisors by lower lip at rest is achieved at the end of treatment.

Section II: Treatment

Treatment Progress

Start of active treatment: Functional Jaw Orthopaedics: November 27, 2018

Comprehensive Orthodontics: October 30, 2019

Age at start of active treatment: 11 years 4 months and 22 days

End of active treatment: October 28, 2020

Active treatment time: 23 months

FJO (11 months) and Fixed Orthodontics (12 months)

End of retention: Ongoing

Key Stages in Treatment Progress

Key stages in treatment progress of this patient are listed in Table 3.

Table 3.

Key Stages in Treatment Progress.

Sl No.	Date	Stage
1.	November 27, 2018	Bite registration for Twin-block appliance.
2.	November 30, 2018	Twin-block appliance was delivered. Instructions were given to sequentially increase the wear time to full-time wear over a 2-week period. Pterygoid response was elicited after 6 weeks.
3.	December 14, 2018	Advised activation of the expansion screw: one quarter turn per week, continued till upper arch width was adequate to accommodate the lower counterpart (Figure 5).
4.	December 31, 2018	Selective trimming was done on the posterior bite blocks to permit differential eruption of lower premolars and molars (Figure 5).
5.	October 23, 2019	Class I incisor relation was established. Stage records were taken for evaluation. Impressions were made for upper anterior inclined bite plane (Figures 6 and 7).
6.	October 30, 2019	Comprehensive fixed orthodontic treatment was started. Upper and lower 0.022 × 0.028″ MBT brackets were bonded to all erupted teeth mesial to permanent first molars except 15. All permanent first molars were banded with lingual sheath attached. 0.014″ U/L NiTi archwires were placed (Figure 8). Upper anterior inclined bite plane was inserted.
7.	November 27, 2019	Second molars were bonded and 0.016″ U/L NiTi archwires were placed.
8.	January 03, 2020	UR5 was bonded and 0.018″ U/L NiTi archwires were placed.
9.	January 31, 2020	U/L coordinated 0.018″ SS AW archwires with compensating curves and molar offset bend for 16 and 26 were given (Figure 9).
10.	March 02, 2020	U/L 019 × 0.025″ NiTi archwires were placed.
11.	March 19, 2020	U/L coordinated 019 × 0.025″ SS archwires with mild compensating curves were placed and class II traction was given (5/16″-4.5 Oz medium force).
12.	July 08, 2020	0.016” U/L NiTi archwires with settling elastics were placed.
13.	October 23, 2020	End of active orthodontic treatment. Upper and lower arches were debonded. Working models for retainers were prepared. Fixed lingual retainers were placed in upper (3-3) and lower (3-3) (Figures 10 and 11).
14.	October 28, 2020	Insertion of upper wrap around with AIBP and lower Begg retainers. Posttreatment records were taken.
15.	September 03, 2021	Follow-up records were taken (Figures 12 and 13).

Source: Patient records

Figure 5.

Source: Patient records.

Figure 6.

Source: Patient records.

Figure 7.

Source: Patient records.

Figure 8.

Source: Patient records.

Figure 9.

Source: Patient records.

Figure 10.

Source: Patient records.

Figure 11.

Source: Patient records.

Figure 12.

Source: Patient records.

Figure 13.

Source: Patient records.

Figure 14.

Source: Patient records.

Mid-Treatment (Postfunctional) Records

• The mid-treatment extraoral and intraoral photographs are given in Figures 6 and 7, respectively.

• Lateral cephalogram on October 23, 2019 (Figure 3).

• Orthopantomogram on October 23, 2019 (Figure 4).

Midtreatment Cephalometric Findings and Their Interpretation

Tables 1 and 2 provide the midtreatment cephalometric values.

The cephalometric analysis revealed a significant decrease in the class II skeletal anteroposterior relationship with an ANB of 3° (from 6.5°) and a Wits appraisal of +1 mm (from +4 mm). There was improvement in the linear measurements of the jaw bases: effective mandibular length improved from 86 mm to 91 mm, and mandibular base extent improved from 59 mm to 62 mm.

The notable changes observed were:

Improvement in the N perpendicular to Pog distance by 4 mm (from −10 mm to −6 mm).

There was a marginal increase in the vertical skeletal parameters: Base plane angle (from 25° to 25.5°), mandibular plane angle (SN-Go-Gn, 34° to 35°), and a decrease in the Jarabak ratio (from 64.2% to 63.4%).

There was a 1° increase in the gonial angle.

Decrease in the upper incisor proclination as seen by reduction in upper 1 to NA angle by 10° (from 33 to 23°) and to SN plane by 11° (from 116 to 105°).

There was a slight increase in the lower incisor inclination (lower incisor to NB increased from 30°/5.5 mm to 33°/7 mm and IMPA increased by 1°).

Both overjet and overbite values have reduced to 2.5 mm and 3 mm, respectively.

Improvement in the soft tissue profile.

Overall, the class II skeletal relationship has improved. The mandible showed favorable horizontal growth changes and was rotated marginally in downward and backward direction, with proportional increase in the vertical face heights. The upper incisors were tipped palatally, and lower incisors were marginally proclined by the Twin-block appliance. The soft tissue relationship has improved.

Section III: Posttreatment Assessment

The posttreatment extraoral and intraoral photographs are shown in Figures 10 and 11.

Occlusal Features

Incisor relationship: Class I

Overjet (mm): 2 mm

Overbite: 2 mm or 30%

Centerlines: Coincident midlines

Left and right buccal Class I molar relation and class I canine relation

Functional occlusal features: Mutually protected occlusion. Canine guidance on left and right lateral excursions with no working or nonworking side interferences. Anterior guidance on protrusion with posterior disclusion. No premature occlusal contacts during mandibular movements.

Complications Encountered During Treatment

During the fixed appliance therapy, the oral hygiene was not satisfactory despite repeated oral hygiene instructions and prophylaxis which resulted in increase in the white spot lesions which was present pretreatment.

Patient was not willing to go for near-end OPG due to the concern for radiation exposure due to which it was avoided. Hence, root parallelism could not be assessed at that stage. However, posttreatment radiographs revealed relatively parallel roots.

Occlusal Indices

• The IOTN (DHC) and IOTN (AC) were 4a and 9 to begin with and 1 at the end for both components.

• The PAR index score changed from the pretreatment 30 to posttreatment 2 with a change of 93.3%.

Radiographs Taken Toward/at the End of Treatment

• Lateral cephalogram on October 28, 2020 (Figure 3)

• Orthopantomogram on October 28, 2020 (Figure 4)

Relevant Radiographic Findings

• Unerupted third molar tooth buds were present in all quadrants except the third.

• Normal condylar morphology.

• Roots were relatively parallel.

• No change in root length of upper incisors.

Posttreatment Cephalometric Findings and Their Interpretation

The posttreatment cephalometric values are provided in Tables 1 and 2.

Skeletal: The posttreatment analysis revealed a considerably stable reduction in the class II skeletal anteroposterior relationship with an ANB of 4° (1° decrease from the postfunctional time period) and with a marginal variation from the postfunctional Wits appraisal (from +1 mm to +2 mm). The saddle angle (122°) and articular angle (145°) both showed no changes, whereas there was 3° increase in the gonial angle (from 127° to 130°). The vertical skeletal parameters showed a slight increase from the pretreatment toward the end of functional appliance therapy and at the end of treatment: base plane angle (from 25° to 27°) and mandibular plane angle (GoGn-SN of 36° from 34). This was reflected by an increase in LAFH by 3 mm from the pretreatment value of 48 mm. However, all these values were close to normal. N perpendicular to Pog value, though improved from −10 mm (pre) to −7 mm (post), did show a mild relapse in the postfunctional period (−6 mm mid).

Dental: The upper incisor proclination measured to NA reduced from the pretreatment value of 33°/6 mm to 23°/4 mm at the end of functional appliance therapy and reduced further to 19°/3 mm toward the end of comprehensive treatment. The lower incisors which showed a mild proclination (L1-NB = 30°/5 mm, IMPA = 101) to start with, were proclined further by 4° (34°/7 mm) by Twin-block therapy but were corrected close to normal (L1-NB = 27°/6 mm, IMPA = 93.5) toward the end of fixed appliance treatment. Both overjet and overbite values are now ideal at 2 and 3 mm, respectively.

Soft Tissue: The upper and lower lip positions respective to E-line are now ideal. The lips are competent with no interlabial gap at rest. Nasolabial angle (100°) falls within the normal range.

Overall, the class II skeletal relationship has improved significantly by a combination of favorable skeletal and dentoalveolar corrections. The corrections achieved are within the stability of the soft tissue paradigm.

Cephalometric Superimposition

Superimpositions of pre-, mid-, and posttreatment cephalometric tracings are shown in Figure 14.

Section IV: Critical Appraisal

• JJ was successfully treated with a combination of myofunctional therapy and comprehensive fixed orthodontics over 23 months. The original treatment aims were accomplished and the patient’s presenting complaint addressed. A good occlusal and aesthetic result was achieved and this was reflected in the PAR and IOTN scores.

• The skeletal base relationship improved with significant improvement in facial profile. Although a slight relapse was observed after the functional phase, favorable intercuspation could be achieved at the end of the treatment.

• Class I molar and canine relation was achieved. A mild rotational relapse was observed in 16, 10 months after debonding. A close monitoring is required for this and if needed, a vacuum-formed clear retainer to correct this may be planned.

• The maxillary incisor inclination was slightly less than ideal at the end of fixed orthodontics. The lower incisors though slightly proclined to begin with and was further proclined by functional appliance therapy, was corrected to near ideal toward the end of comprehensive fixed orthodontics. Ideal overjet and overbite were achieved with a class I incisor relation.

• In spite of meticulous oral hygiene instructions and repeated ultrasonic scaling, enamel opacities were observed on multiple teeth. Prophylactic use of fluoride mouth rinse has been prescribed and a close monitoring is scheduled.

• The status of third molars is to be evaluated during follow-up and if impacted or unfavorable, she will be advised to undergo extractions of the same.

Discussion

The IBO category II requires a case of class II malocclusion with an ANB of more than 5° treated using growth modification and fixed appliance. ⁴ The above case had an ANB of 6.5° and Wits appraisal of +4 mm justifying the inclusion under category II. Patient was in CVMI stage 3 with mandibular retrognathism and positive VTO, hence growth modification using functional appliance was planned. Twin-block was selected due to patient comfort, affordability, and availability of remaining growth and time.^{5, 6} Traditionally, 2-phase treatment was suggested for class II malocclusion, where the first phase was done in the mixed dentition stage using functional appliances followed by a period of retention for 1 to 1.5 years and in the second phase in early adolescence another course of comprehensive fixed appliance treatment with or without functional appliance is undertaken. ⁷ However, the evidence is now clear that a 2-phase treatment is no more superior to 1-phase treatment and the former is recommended only in cases of anticipated traumatic dental injury or psychosocial issues.^8-11

The most critical issue in integrated single-phase treatment when removable functional appliance is used includes maintenance of the bite correction during the transition stage from removable to fixed appliance. ¹² Many appliances including EVAA, Steep and Deep, and AIBP were recommended until class II mechanics with rigid wire is initiated. An AIBP retained using ball end clasp was used in this case. The reciprocal lower incisor proclination was controlled using incorporation of labial root torque in the lower labial segment and use of short class II elastics.

Molar derotations can be addressed in many ways including the use of TPA with derotation moments, over-corrected molar tube positions, fourth order bends incorporated in archwires, couple forces generated from adjacent teeth, or from mini-implants. 0.018 SS Australian archwire with asymmetric toe-in bends was used to derotate UR6 and maintained thereafter.

Retention following growth modification and comprehensive treatment may be a problem at times considering the unfavorable pattern of growth that can still persist. Hence, a prolonged retention of the sagittal correction and deep bite is essential along with the dental corrections. Continued use of an ABP or AIBP is thus essential and followed in this case too during this phase.