|Year : 2019 | Volume
| Issue : 1 | Page : 69-76
Treatment of a severe tooth size-arch length discrepancy using rapid maxillary expansion and mandibular incisor extraction: An unconventional combination approach
Harpreet Singh1, Pranav Kapoor2, Poonam Sharma3, Raj Kumar Maurya4, Tanmay Mittal5, Deepak Kumar Bhagat6
1 Associate Prof., Department of Orthodontics and Dentofacial Orthopedics, ESIC Dental College and Hospital, New Delhi, India
2 Prof., Department of Orthodontics and Dentofacial Orthopedics, ESIC Dental College and Hospital, New Delhi, India
3 Prof., and Head, Department of Orthodontics and Dentofacial Orthopedics, ESIC Dental College and Hospital, New Delhi, India
4 Assistant Prof., Department of Orthodontics and Dentofacial Orthopedics, Army Dental Centre (Research and Referral), New Delhi, India
5 Tutor, Department of Orthodontics and Dentofacial Orthopedics, ESIC Dental College and Hospital, New Delhi, India
6 Intern, Department of Orthodontics and Dentofacial Orthopedics, ESIC Dental College and Hospital, New Delhi, India
|Date of Submission||20-May-2018|
|Date of Acceptance||04-Sep-2018|
|Date of Web Publication||04-Feb-2019|
Dr. Raj Kumar Maurya
Department of Orthodontics and Dentofacial Orthopedics, Army Dental Centre (Research and Referral), New Delhi
Source of Support: None, Conflict of Interest: None
Rapid maxillary expansion (RME) has proven to be a viable treatment option for space gaining in maxilla. Similarly, mandibular incisor extraction when used in aptly selected cases has been reported to be a valuable adjunctive therapy to relieve tooth size-arch length discrepancy in mandibular arch. However, cases reporting the concomitant use of both these modalities are few. The objective of the present article is to report the successful orthodontic treatment of severe tooth size-arch length discrepancy in an adolescent patient using a combination of nonextraction treatment including RME, proclination of anterior teeth and reproximation in the maxillary arch, and single incisor extraction in the mandibular arch. Through a meticulously planned individualized treatment approach, esthetically and functionally stable results with good occlusion were achieved, which were well-maintained at 3-year follow-up. The favorable treatment outcome and long-term stability achieved substantiates the feasibility of this unconventional treatment option in selected cases.
Keywords: Mandibular incisor extraction, maxillary expansion, reproximation, severe tooth size-arch length discrepancy
|How to cite this article:|
Singh H, Kapoor P, Sharma P, Maurya RK, Mittal T, Bhagat DK. Treatment of a severe tooth size-arch length discrepancy using rapid maxillary expansion and mandibular incisor extraction: An unconventional combination approach. J Indian Orthod Soc 2019;53:69-76
|How to cite this URL:|
Singh H, Kapoor P, Sharma P, Maurya RK, Mittal T, Bhagat DK. Treatment of a severe tooth size-arch length discrepancy using rapid maxillary expansion and mandibular incisor extraction: An unconventional combination approach. J Indian Orthod Soc [serial online] 2019 [cited 2019 Apr 26];53:69-76. Available from: http://www.jios.in/text.asp?2019/53/1/69/251558
| Introduction|| |
Tooth size-arch length discrepancies represent a significant component of all malocclusions among orthodontic patients. Crowding, impaction, and incisor proclination are common manifestations of tooth size-arch length discrepancies. Treatment modalities routinely employed for such patients include extraction, interproximal reduction, expansion, incisor proclination, and molar distalization. The extraction versus nonextraction debate has always been a topic of concern and controversy. Arch expansion not only prevents the detrimental effect of improperly planned extractions on facial esthetics but also facilitates the complete development of the dental arch, thus allowing the teeth to be orthodontically repositioned within the enhanced alveolar processes, and eliminating the need for the removal of permanent teeth in many cases.
Space gaining by anteroposterior and transverse expansion of maxillary dental arch has proved to be a viable and stable treatment option in aptly selected cases. The benefits of capitalizing the orthopedic (separation of two halves of the maxilla resulting in increase in transverse arch dimensions) and orthodontic (buccal movement of the posterior teeth and alveolar process) effects of rapid maxillary expansion (RME) and concurrent mandibular dentoalveolar expansion for correction of tooth size-arch length discrepancies and developing skeletal, dentoalveolar, and muscular imbalances are well documented in literature. In addition, mandibular incisor extraction has been reported as a valuable therapeutic alternative for significantly crowded lower dentitions in carefully selected cases.,
However, case reports demonstrating the concomitant use of RME along with incisor extraction therapy in the mandibular arch for the correction of dentoalveolar Class I malocclusions in permanent dentition are very limited. The present report describes the treatment process and long-term stability of the successful esthetic and functional outcome of combination of RME and single mandibular incisor extraction for the management of severe arch size-tooth material discrepancy.
| Case Report|| |
A 13-year-old boy reported to the Department of Orthodontics and Dentofacial Orthopedics with the chief complaints of “uncomfortable bite” and unesthetic appearance of his maxillary and mandibular anterior teeth [Figure 1]. He had very low self-esteem as he was constantly bullied due to his cosmetically unpleasing smile. His medical history and dental history were noncontributory.
Diagnosis and etiology
The patient had a skeletal Class I jaw-base relationship and a mesofacial pattern with a tendency to lip retrusion. The nasolabial angle was slightly increased, with adequate chin prominence. The temporomandibular joints were normal, and his face was symmetric. Unattractiveness of the posed smile was evident by excessive mandibular incisor display with negligible maxillary incisor vertical display on smiling. Intraorally, he was in the early permanent dentition stage of development with a retained maxillary right second deciduous molar and maxillary left deciduous canine. He had an Angle Class I molar relation on both sides, with an overbite and overjet of 6 and 3 mm, respectively. Severe crowding was present in both maxillary and mandibular arches. Both the maxillary central incisors and maxillary left lateral incisor were in crossbite, and maxillary right lateral incisor was rotated mesiolabially. The labial aspect of the crown of the left maxillary lateral incisor was abutting the crown of the left maxillary central incisor. Severe labial gingival recession was observed in relation to mandibular right and left central incisor [Figure 1]. Transverse dental compensations were observed with buccally inclined maxillary posterior teeth. However, the mandibular posterior teeth exhibited relatively normal inclinations. With regard to the functional examination, anterior mandibular displacement (with no lateral displacement) was observed on jaw closure from the initial contact position to centric occlusion position. Space analysis indicated a discrepancy of 11 and 6.5 mm in maxillary and mandibular arches, respectively. Severe crowding resulted in inadequate space for eruption of the left maxillary canine. Bolton's analysis revealed anterior tooth material excess in both arches. Pont's analysis indicated the need for expansion in maxillary arch.
Panoramic radiograph demonstrated a full complement of teeth including developing third molars [Figure 2]a. The roots of the maxillary right second deciduous molar showed 40% resorption, and the succedaneous premolar had 70% root development. IOPA X-ray showed normal root morphology of maxillary left central and lateral incisor [Figure 2]b and [Figure 2]c.
|Figure 2: (a) Pre-treatment panoramic radiograph; (b) Pre-treatment intraoral periapical X-ray; (c) Pre-treatment maxillary occlusal radiograph|
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Lateral cephalometric analysis revealed a skeletal Class I jaw base relationship (ANB, 1°; Wits appraisal,-2 mm), retrognathic maxilla (SNA 80°), and a mild hypodivergent skeletal pattern (SN-GoGn 28°) [Figure 3] and [Table 1]. The maxillary incisors were retroclined (U1 to SN, 94°), whereas the mandibular incisors were proclined (L1 to A-Pog, 6 mm; IMPA, 108°). Soft-tissue analysis confirmed retrusive upper and normal lower lip. Based on cervical vertebrae maturity indicators assessment, the patient was approaching the peak of the growth spurt and was in acceleration (early CS4) stage.
The patient was diagnosed as having an Angle's Class I Dewey's Type 1 malocclusion with anterior crossbite in relation to maxillary right and left central incisors and maxillary left lateral incisor. In accordance with the literature, the etiology of the malocclusion could be attributed to a combination of genetic and environmental factors.
The treatment objectives were to (i) address the severe arch-length deficiency in maxillary and mandibular arch, (ii) attain adequate space to alleviate anterior crowding and facilitate eruption of maxillary left canine, (iii) improve lip support, (iv) improve periodontal health in lower anterior region, (v) achieve esthetically favorable and functionally effective overjet and overbite, (vi) establish optimal and stable functional occlusion, and (vii) achieve a balanced soft tissue profile.
Possible treatment options including premolar extraction and non-extraction therapy were considered. Since the extraction of all 4 first premolars would have resulted in retroclination of maxillary incisors, leading to a concave and exceedingly flat profile, therefore, extraction therapy was not considered as a viable treatment option. Considering the relatively young age and the influence of growth on dentofacial esthetics, non-extraction modality involving carefully monitored “RME” was deemed a better treatment option for the correction of anterior crossbite, alleviation of anterior maxillary crowding, and improvement in facial profile. In the mandibular arch, a tooth size discrepancy of 6.5 mm along with severe labial gingival recession and the absence of a discernible external alveolar lamina indicated the need for mandibular incisor extraction. This would help achieve optimal anterior alignment while observing the anatomic limits of the narrow symphysis and avoiding the risk of long-term instability. Considering the ensuing residual overjet and obvious tooth size discrepancy following mandibular incisor extraction, the need for reproximation in the maxillary arch was kept in mind.
Following the extraction of retained maxillary right second deciduous molar to facilitate spontaneous eruption of the second premolar, maxillary expansion was initiated 3 months later with the use of a tooth-borne Hyrax assembly [Figure 4]a and [Figure 4]b. The patient was instructed to activate the appliance once a day for 21 days, creating an opening of 5.5 mm i.e., semi-RME protocol was followed, which involved activation of the screw by two-quarter turns per day for the first eight days, followed by one-quarter turn per day every other day for the next 13 days. Once sufficient expansion had been achieved with the buccal crest of the palatal cusps of the upper posterior teeth just approximating the lingual crest of the buccal cusps of the lower permanent molars, the screw was locked with a double ligature tie, and the expander served as a stabilizer for the next 3 months. During the stabilization period, 0.022” × 0.028” slot pre-adjusted edgewise brackets (MBT prescription) were bonded on all anterior maxillary teeth except for the palatally locked left lateral incisor [Figure 4]c and [Figure 4]d. Once the anterior segment was sufficiently aligned, the bonded expander assembly was removed and posterior maxillary arch was bonded using a level-slot lineup technique. A compressed nickel-titanium open-coil spring on a 0.016” × 0.022” stainless steel (SS) wire was used to open the needed space for left lateral incisor. During this time, after extraction of mandibular right central incisor, pre-adjusted edgewise appliance was placed in the mandibular arch [Figure 5]a, [Figure 5]b, [Figure 5]c.
|Figure 4: (a) Intraoral frontal view with bonded Hyrax assembly in situ; (b) Maxillary occlusal view with bonded Hyrax assembly in situ; (c) Treatment progress frontal photograph depicting expansion with Hyrax assembly; (d) Treatment progress occlusal view after expansion and progression of anterior alignment with sectional-fixed appliances|
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|Figure 5: (a) Treatment progress frontal view depicting space creation for blocked out lateral incisor; (b) Treatment progress right lateral view; (c) Treatment progress left lateral view; (d) Stage photograph depicting progression of alignment of blocked out lateral incisors; and (e) Stage photograph showing aligned incisors|
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Due to unforeseen circumstances, the patient failed to report for 3 months, following which, a “row-boat” effect was observed in the maxillary arch resulting in mesial movement of maxillary teeth right first permanent molar. The correction of molar relationship necessitated the distalization of the upper first molar using compressed superelastic NiTi open-coil spring with indirect anchorage provided by a mini-implant placed between second premolar and first molar. Once molar had been distalized into a super Class I relation, a transpalatal arch was placed to stabilize the regained molar position.
After adequate space creation (by activating the open-coil spring) for blocked out maxillary and mandibular left lateral incisor, MBT bracket was bonded in an inverted position on the labial surface to permit labial movement of the crown [Figure 5]d and [Figure 5]e. A normal progression of continuous archwires was used to level, align, and coordinate the arches. To compensate for the residual overjet and anterior tooth size discrepancy, mild interproximal stripping was performed on the distal aspect of the teeth in the upper left quadrant. Incorporation of resistant lingual root torque helped avoid excessive linguoclination of maxillary anterior teeth.
Based on the requirements of the teeth, first- and third-order bends were placed in the maxillary and mandibular continuous SS rectangular arches of 0.019” × 0.025” dimension to finalize the tooth positions. 0.019” × 0.025” sectional beta-titanium (TMA) wire with tie-back was used during the finishing stage for improving torque in maxillary incisor region. Full-time wear of 3/16” (2 oz) short Class II and vertical spaghetti elastics facilitated in optimal occlusal interdigitation.
After settling and detailing of occlusion, the fixed appliances were debonded, and circumferential retainers were placed in maxillary and mandibular arches to maintain the tooth positions. Due to excellent patient perseverance and compliance, it was decided to continue with retainers worn full time for 1 year, followed by additional 1 year of nighttime wear. The patient was also advised to visit oral surgeon every 6 months for evaluation of third molars.
The total duration of orthodontic treatment was 23 months. Post-treatment final records showed significant improvement in facial esthetics along with the establishment of optimal overjet of 3 mm, overbite of 3 mm, and well-intercuspated buccal occlusion with canine guidance [Figure 6]. Better lip support and improved nasolabial angle contributed to improved profile esthetics. Dramatic improvement of lip line, smile width, and smile arc was discernible without mandibular incisor display on smiling. Treatment resulted in a significant increase in the maxillary intercanine width (before and after were 31 and 36.5 mm), at the same time maintaining the mandibular intercanine (19 mm), and intermolar width (31.5 mm) dimensions. The initial transpalatal first molar width of 32.5 mm increased by 2.5 mm to a normal arch width of 35 mm.
|Figure 6: Post-treatment photographs showing improved facial esthetics and well-aligned teeth with good intercuspated occlusion|
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Post-treatment panoramic radiograph revealed acceptable root parallelism with no signs of bone or apical root resorption [Figure 7]. Post-treatment lateral cephalogram showed favorably improved skeletal, overjet, and overbite relationships (ANB, +3°; Wits appraisal, +2 mm), with improvement in the inclination of maxillary incisors (U1 to SN, 112°) and retroclination of mandibular incisors to normal positions (IMPA,100°) [Figure 8] and [Table 1]. Soft-tissue analysis showed improved relationships of chin, lips, and nose to Holdaway line. Cephalometric superimposition demonstrated improvement in anteroposterior relationship (Wits appraisal,−2 mm–+2 mm), and sagittal position of maxilla (SNA, 80°–83°) along with continued favorable maxillary and mandibular growth [Figure 8] and [Figure 9].
|Figure 8: (a) Post-treatment lateral cephalogram, and (b) superimposed pre-treatment and post-treatment cephalometric tracings|
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At 3-year follow-up, the patient demonstrated stable intermaxillary dental relationships and well-maintained acceptable facial profile without obvious relapse [Figure 10].
|Figure 10: A 3-year follow-up photographs demonstrating well-maintained pleasing profile esthetics and stable occlusal results|
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| Discussion|| |
The extraction versus non-extraction dilemma has always been one of the concerns and controversy for the orthodontist, especially when managing cases with severe tooth size-arch length discrepancy. Proponents of extraction therapy believe that extracting teeth is necessary for orthodontic correction to respect the limits of the dentition and achieve proper esthetics, health of the oral tissues, and occlusal stability. On the contrary, nonextraction treatment is advocated by others, based on the premise that the physiologic function of the dentofacial complex determines its form and in many cases, a full complement of teeth is necessary for proper growth and development.,
One of the nonextraction approaches to treatment is RME, which has proven to be a biologically and biomechanically sound technique for addressing transverse and anteroposterior discrepancies in orthodontics., In cases where the lower arch is within the normal range, and premolar extractions are not indicated, rational and judicious use of RME in permanent dentition in the absence of posterior crossbite is justifiable for increasing the maxillary arch perimeter for provision of adequate space for the resolution of maxillary anterior crowding. Numerous factors such as soft-tissue profile, health of oral tissues, inclination of the posterior teeth, individual growth potential, and posttreatment stability should be taken into consideration when making treatment decision for RME in these patients. A transpalatal width of 35–39 mm suggests adequate size of bony base to accommodate average-sized permanent teeth. In the present case, semi-RME was used to gain arch perimeter and avoid extractions since the patient had a transpalatal width of 32.5 mm in the molar region. Semi-RME allowed for more physiologic adjustment at the maxillary articulations and surrounding skeletal structures, thus resulting in the reduction of relapse in the postretention period. The posterior bite block effect of bonded acrylic splint expander prevented the extrusion of posterior teeth.
Apart from 4 mm of space gained from semi-RME, 5 and 2 mm of space were gained from incisor proclination (2.5 mm labially) and reproximation, respectively. In addition, 2 mm of space that was lost because of mesial drift of maxillary right first permanent molar following the patient's missed appointment was regained by unilateral maxillary molar distalization.
Due to the negligible effect of spontaneous transverse RME on the perimeter of the mandibular arch, some space-gaining procedures involving the use of lingual arch or a lip bumper are usually necessary to “coordinate” the treatment effect. A “middle of the road” approach for gaining space in the anterior segment of the mandible is the extraction of one of the lower incisors which helps resolve tooth size-arch length discrepancy in carefully selected cases. Various clinical criteria, such as the clinical and periodontal condition of the teeth, mechanics applied, facial pattern, esthetic and functional alterations, treatment duration and treatment stability, should be taken into consideration during decision-making process for a single mandibular incisor extraction in a patient. In the present case, considering the patient's age (13 years with completed mandibular intercanine width dimension), bilateral Class I molar relationship and localized anterior mandibular tooth size-arch length discrepancy, extraction of single mandibular central incisor was deemed more appropriate for supplying adequate space for the resolution of mandibular crowding.
Myriad clinical situations best suited for mandibular incisor extraction include: (i) anomalies in number of teeth, (ii) tooth size anomalies (Relative macrodontia of lower incisors/microdontia of the upper lateral incisors/inherent morphological defects of the lower incisor, (iii) ectopic eruption of incisors (associated with gingival recession), (iv) moderate Class III malocclusion with anterior crossbite, or edge-to-edge incisors relationship or tendency toward anterior open bite, and (v) fan arrangement of lower incisors with acceptable buccal occlusion bilaterally. Mandibular incisor extraction offers the advantages of a reduced treatment time and the possibility of achieving better long-term stability in the mandibular anterior segment since intercanine width is maintained and mandibular anteriors are aligned upright on the apical base. In addition, as compared to mandibular premolar extractions, single incisor extraction proves to be beneficial in cases with pleasing pretreatment profiles, since the minimal incisor retraction involved precludes any unfavorable soft-tissue profile changes with aging. Caution, however, should be exercised to avoid unfavorable clinical outcomes regarding gingival recession, open interproximal gingival embrasures, and increased overjet and overbite.
A major concern in mandibular arches is tendency to relapse following transverse expansion of the mandibular intercanine dimension. In a meta-analysis evaluating the stability of the mandibular intercanine dimension treatment change in 1233 patients, Burke et al. concluded that it is more prudent to maintain the original intercanine dimension. Riedel et al. have reported greater anterior alignment stability with lower incisor extraction in the absence of permanent retention. Similarly, Canut also observed improved alignment stability with mandibular incisor extraction as compared to premolar extraction therapy. In the present case, extraction of the extremely malpositioned and periodontally compromised incisor helped achieve posttreatment stability since unnecessary movement of multiple teeth was avoided by limiting the correction to a specific dentition zone. In addition, as demonstrated by the 3-year follow up records, the stability in the maxillary arch was well-maintained.
As for long-term stability of treatment with RME, Canuto et al. reported that RME does not influence long-term maxillary anterior alignment stability. Similarly, Mohan et al. also reported no differences for the long-term intermolar width stability in patients (with or without posterior crossbite) treated with rapid palatal expansion in the mixed dentition versus the permanent dentition.
As a treatment option, expansion in the maxillary arch is easy to achieve but at the same time difficult to retain. Variables potentially affecting alignment stability of maxillary incisors include age of the patient, duration of retention, initial severity of crowding, relapse of teeth in the opposite side, changes in arch dimensions, presence of pre-treatment rotations, and lack of complete correction of rotated teeth resulting in inadequate tight interproximal contacts.
To help improve the predictability of proposed treatment plan, diagnostic setup was deemed indispensable for visualization of the intended post-treatment occlusion, evaluating the feasibility of lower incisor extraction, and simulating the effects of resulting incisal guidance for articulating six maxillary anterior teeth with five mandibular anterior teeth.
As determined in advance by means of the diagnostic setup, incorporation of any one or combination of the following compensatory orthodontic movements has been suggested to restore disocclusion function of the teeth:, (a) positioning of the upper canine with a mesial crown inclination, (b) decreasing the upper canine prominence by reducing or removing the offset on the mesial side of the upper canines, (c) upright positioning of the lower canines, (d) increasing lower canine prominence by incorporation of mild distal offset, (e) incorporation of artistic bends in the lower incisors in the nonextraction quadrant in order to consume space and distalize the lower canines, and (f) reproximation of the upper incisors to facilitate mesial movement of the maxillary canines. In our patient, reproximation in the upper left maxillary labial segment facilitated management of the slight upper anterior tooth size excess and helped achieve optimum anterior fit and cuspid-protected occlusion.
Evaluation and management of each case should be based on its individual merits. Individualized treatment plan envisaging the principle of goal-oriented orthodontic therapy can significantly contribute to the straightforward treatment of certain malocclusions and the pursuit of excellence in treatment results regarding optimizing structural balance, esthetic harmony and functional stability. With 11 mm of arch length deficiency in the maxillary arch, the adoption of non-extraction approach presented a management, prognostic, and stability challenge. Even so, well-planned and judicious combination of space gaining modalities involving transverse expansion, incisor advancement, and reproximation, at the same time respecting the anatomic limits of the dentition and the apical base were effective in alleviation of severe maxillary crowding and enhancing the facial esthetics.
The reasonably stable results observed 3 years after the completion of treatment without retention suggest that ensuring absolute patient compliance to prolonged retention and regular long-term follow-up, predetermining precise occlusal possibilities resulting from concomitant upper non-extraction and lower single incisor extraction, optimal intercuspated occlusion and function, individual adaptation, and favorable growth pattern, all combine in maintaining long-term results.
| Conclusion|| |
Resolution of severe arch length discrepancy by combined maxillary non-extraction and single mandibular incisor extraction modality is one of the most challenging and satisfying treatments to plan and accomplish. The present case report demonstrates the feasibility of unconventional, yet effective combination of meticulously executed maxillary orthopedic expansion and mandibular incisor extraction therapy in achieving acceptable esthetic, occlusal, and functional outcomes with impressive long-term stability.
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
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]