Successful treatment of Class II malocclusion with bidental protrusion using standard edgewise prescription.

This case report deals with the successful orthodontic treatment of a 14-year-old female patient having Class II malocclusion with bidental protrusion using standard edgewise prescription. She reported with forwardly placed upper front teeth and difficulty in closing lips. She had prognathic maxilla, retrognathic mandible, and full cusp Class II molar and canine relation bilaterally with overjet of 7 mm. She was in cervical vertebrae maturation indicator Stage IV. The case was treated by fixed extraction mechanotherapy. Interarch Class II mechanics was used to retract the upper incisor and to mesialize the lower molars. Simultaneously, Class I mechanics was used to upright lower incisors. Tip back bend, curve of Spee, and extra palatal root torque were incorporated in upper archwire to maintain molars in upright position and prevent extrusion and deepening of bite, respectively. There was satisfactory improvement in facial profile at the end of 24 months. After a follow-up of 6 months, occlusion was stable.

Introduction

Class II malocclusion is the most common reason for seeking orthodontic treatment though it is second in frequency distribution, among the three classes of malocclusion.[1]

Bidental protrusion is a condition characterized by protrusive and proclined upper and lower incisors and an increased protrusion of the lips. The primary objective of correction of dentoalveolar protrusion includes the retraction and retroclination of incisors with a resultant decrease in soft-tissue convexity and procumbency.[2]

Among the treatment options available for bidental correction, the most often used one is the extraction of the four first premolars since they are located nearest to anterior segments of the dental arches which allow direct access to crowding and severe dentoalveolar protrusion correction.[3] Another alternative is the removal of the first maxillary premolars and the second mandibular premolars. It is used in cases of Class II with bidental protrusion with severe upper anterior discrepancy or mild to moderate dentoalveolar protrusion and in a mandibular arch with mild anterior discrepancy or dentoalveolar protrusion.[4]

In our case, extraction pattern followed was extraction of maxillary first premolar and mandibular second premolar for correction of dentoalveolar protrusion and to achieve angle's Class I molar relation bilaterally.

Case Report

A 14-year-old female patient reported with forwardly placed upper front teeth and inability to close lips. She had convex facial profile, mesoprosopic facial form, acute nasolabial angle with potentially competent lips, and oronasal breathing pattern [Figure 1].

Figure 1

Pretreatment extra- and intra-oral photographs and orthopantomogram

Smile was nonconsonant, commissural, and bilaterally symmetrical with narrow buccal corridor space [Figure 1].

Intraorally, she had proclined maxillary and mandibular incisors with dentoalveolar protrusion, overjet of 7 mm, and overbite of 4 mm. She had full cusp Class II molar and canine relation bilaterally with “U” shaped upper and lower arches [Figure 1].

Cephalometric analysis revealed that she had cervical vertebrae maturation indicator (CVMI) Stage IV with skeletal Class II base due to prognathic maxilla with retrognathic mandible, average growth pattern and bidental protrusion [Figure 2].

Figure 2

Pre- and post-treatment cephalometric analysis and cephalogram

Panoramic radiograph showed full complement of teeth in maxillary and mandibular arch except third permanent molars in all quadrant, which were in almost crown completion stage [Figure 1].

Diagnosis

A 14 year old female patient presented with the chief complaint of forwardly placed front teeth. She had Angle's class II molar relation with bidental protrusion on skeletal Class II bases due to prognathic maxilla and retrognathic mandible, average growth pattern, and potentially incompetent lips. The cervical vertebra analysis showed CVMI stage IV.

Treatment objective

Objectives were to establish normal overjet and overbite, correct dentoalveolar protrusion, achieve and maintain Class I molar and canine relation bilaterally, and improve lip competency, the facial profile, and esthetic of the patient.

Treatment plan

It was planned to treat case with extraction of first premolars in maxillary arch and second premolars in mandibular arch using maximum anchorage in upper arch and minimal anchorage in lower arch.

Treatment was started after thorough oral prophylaxis and polishing of teeth. Bonding was done using a standard edgewise appliance of slot size 0.022” × 0.028”, followed by levelling and alignment using 0.014” stainless steel (SS) multiple loop archwire. After that, series of gradually increased dimension archwires from 0.016” to 0.018” × 0.025” SS were made with the first and second order bends, molar stops with accentuated curve of Spee for bite opening.

At the end of 6 months, canines were retracted in upper arch by using 150 g, 9 mm nickel titanium close coil spring to reduce the size of anterior retracting unit. A 0.019” × 0.025” SS retraction archwire was made without molar stops and accentuated curve of Spee and ligated in upper and lower arch. Class II elastics were used to retract the upper incisor and mesialize the lower molars [Figure 3]. Maxillary archwire was modified to minimize the extrusion and distal tipping of incisors by adding extra palatal root torque and curve of Spee. The tip back bends were placed in upper arch and just distal to the first premolar bracket in lower arch to maintain maxillary molar in upright position and allow unobstructed mesial slide of lower molars, respectively. We soldered hook just distal to lateral incisor to increase the horizontal component to avoid extrusion of lower molar and increase in vertical dimension [Figure 3].

Figure 3

Mid-treatment intraoral photographs with Class II elastics

Class II elastics of 5/16 inch, medium forces in the range of 4–6 OZ were used. Elastic placement was carefully demonstrated to the patient. Simultaneously, elastic chain was given in lower arch to retract lower incisors and to burn anchorage. Settling was done in 0.016” SS archwire with 1/8” light settling elastics. Desired objectives were achieved at the end of 24 months [Figure 4]. After that, case was debonded and wrapped around retainer along with lingual bonded retainer were issued to retain the stable occlusion. After a follow-up of 6 months, occlusion was stable [Figure 5].

Figure 4

Posttreatment extra- and intra-oral photographs and orthopantomogram

Figure 5

Post follow-up extra- and intra-oral photographs

Discussion

Management of Class II malocclusion in nongrowing individuals usually involves selective extraction of permanent teeth, with subsequent dental camouflage to hide the skeletal discrepancy or orthognathic surgery.[5] Recent studies have shown that dental compensation with camouflage treatment has similar results as orthognathic surgeries.[6]

Keating studied the features of bidental protrusion in Caucasian population using cephalometrics. He reported that bimaxillary protrusion was associated with a longer and more prognathic maxilla, shorter posterior cranial base, and a mild Class II skeletal pattern.[7] The successful orthodontic correction of the bidental protrusion has been reported by Tan when cases were treated with extraction of all first premolars.[8]

Extractions of premolars in Class II bidental protrusion case, if they are undertaken after a thorough diagnosis, lead to a positive profile change.[7] In Class I dental protrusion cases, extraction of all first premolars is mostly recommended and extraction spaces are utilized for retraction of anterior.[8] While in Class II, upper first premolars and lower second premolars are recommended because upper extraction space is utilized for retraction of upper anterior and lower space is utilized for mesialization of molars as well as to upright the incisors.[4]

In our case, there was full cusp Class II molar relation bilaterally with bidental protrusion and IMPA of 107° [Figure 2]. To correct these, the extraction of first premolars in upper arch and second premolar in lower arch was planned.[1]

It is more favorable to use Class II elastics when the skeletal jaw discrepancy is mild to moderate.[9] The objectives of Class II elastics are different in nonextraction or an extraction situation, In extraction situation, the main objectives are to enhance lower mesial molar movement.[1] Greater the distance between the points of engagement of Class II elastic, greater will be the horizontal vector that will favorably bring mandibular posterior dentition forward and to reduce extrusion of molars.[9] Mandible was advanced in our case by 2 mm (Pog to N perpendicular reduced by 2 mm) due to effect of Class II elastics [Figure 6].

Figure 6

Pre- and post-treatment superimposition on SN-plane registered at S

We treated case with standard edgewise appliance because high degree of control afforded by the edgewise bracket, each tooth is always under complete mesiodistal tip control.[10] Kattner and Schneider observed that there was no differences in the ideal tooth relationship index, when they compared the study models of patients treated using standard edgewise appliances with those treated using Roth preadjusted edgewise prescription.[11]

Conclusions

Case report shows that mild to moderate Class II malocclusion with bidental protrusion in nongrowing subject can be treated well with extraction of the first premolars in upper and second premolars in lower arch with Class II elastics using standard edgewise appliances.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.