Class II Malocclusion with Crowding, Missing LR2 and Ectopic Eruption of UR3 is Treated Conservatively with Maxillary Retraction

Drs. Cheng WT, Lin JJ, Roberts WE.

Abstract

Introduction:A 22-year-old female presented for orthodontic consultation to evaluate a chief complaint: high upper right canine (UR3).

Diagnosis:Clinical and radiographic examination revealed a convex facial pro le (G-Sn-Pg’ 18°), slightly protrusive lips (E-line: UL 1mm, LL 3mm), mentalis strain, upper dental midline deviation to the right, congenitally missing LR2, Class II malocclusion, ectopic labial eruption of the UR3, maxillary crowding 8-9mm, a relatively low mandibular plane angle (SN-MP 30, FMA 20). The Discrepancy Index was 27 points.

Treatment: All permanent teeth were erupted including third molars. Following extraction of all four third molars, a passive xed self-ligating (PSL) appliance was installed. At the same appointment, infrazygomatic crest (IZC) bone screws were inserted to provide posterior skeletal anchorage to retract both arches. Additional space was achieved by slightly expanding both arches, and interproximal reduction (IPR) as needed. Initial alignment was achieved via a 0.014-in and 0.014x0.025-in copper nickel titanium (CuNiTi) archwire. As the maxillary buccal segments were retracted, the bite was opened with an anterior bite turbo. Maxillary buccal segments were differentially retracted with elastomeric chains anchored with the IZC bone screws. Active treatment time was 23 months.

Outcomes:The upper dental midline was about 2mm right of the facial midline. The lower arch was nished in Class I on the left side and Class III on the right to compensate for the missing LR2. Vertical dimension of occlusion (VDO) and lower facial height (LFH) were increased about 2mm, resulting in 1° change in the mandibular plane angle. Despite the missing LR2, a good compromised occlusion was achieved as evidenced by a Cast-Radiograph Evaluation (CRE) of 21 and Pink & White Esthetic Score of 6 points. The maxillary incisors were retracted ~3mm to reduce lip protrusion and achieve lip competence. The decreased lip protrusion helped mask the increase in LFH, so no change in facial convexity (18°) was evident.

Conclusion:This challenging malocclusion with an ectopic erupted canine (DI=27), was treated conservatively in 23 months to a good dental alignment (CRE=21). PSL brackets, IZC bone screw anchorage and Class III elastics were effective mechanics for alignment and retraction of the maxillary arch to relieve crowding and provide space to align an ectopically erupted UR3. (J Digital Orthod 2018;50:4-20)

Key words:Congenitally missing, lower lateral incisor, ectopic eruption, maxillary canine, passive self-ligating appliance, infrazygomatic bone screw, extra-alveolar anchorage, anterior bite turbo, arch retraction, facial convexity
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Asymmetric Class II Malocclusion Acquired from Early Loss of a LR6 and UL Primary Canine: Reverse the Etiology and Align a Horizontally Impacted LR8 with a Ramus Bone Screw

Drs. Huang C, Su BCW, Chang CH, Roberts WE.

Abstract

Introduction: A 26 yr female presented with a chief complaint of “missing and crooked teeth.”

Diagnosis:Compensated Class II, division 2 malocclusion was complicated with severe crowding, reduced axial inclination of upper and lower incisors, decreased lip protrusion, blocked-in UL5, lingual crossbite LL7, missing LR6, and horizontally impacted LR8. The American Board of Orthodontics (ABO) Discrepancy Index (DI) was 24.

Etiology:The cause of this severe acquired malocclusion was deemed premature loss of two teeth: LR6 due to Molar Incisor Hypomineralization (MIH), and UL deciduous canine due to UL2 ectopic eruption.

Treatment:Reverse the maxillary portion of the etiology by opening space to align the UL5. Correct the mandibular discrepancy by moving the LR7 mesially, uprighting LR8 with ramus bone scarew (RBS) anchorage, and align the LR7 and LR8 in the LR6 and LR7 positions. Extract the UR8 and LL7, and then align the LL8 in the LL7 position. Active treatment time: 36 months.

Outcomes:Facial, dental and smile esthetics were near ideal. Both arches were well aligned. The LR7 and LR8 were substituted into the first and second molar positions. Despite successful molar substitution, correction of incisal axial inclinations, and achieving excellent dentofacial esthetics, there was a residual Class II intermaxillary relationship. The Cast-Radiograph Evaluation (CRE) was 33, and the Pink & White dental esthetic score was 0.

Conclusion:RBS anchorage is efficient mechanics for recovering a severe horizontal impaction in the posterior aspect of the mandibular arch. Substitution of a recovered impaction for a missing mandibular molar is a viable clinical option. However, uprighting and aligning impactions is a technique sensitive approach that requires careful planning and execution. (J Digital Orthod 2018;50:26-46)

Key words:Adult complex treatment, ramus bone screw, horizontal impaction, third molar, uprighting mechanics, molar substitution, space closure, midline correction, pegged lateral incisor, camou age treatment, MIH
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Management of an Impacted Maxillary Canine with the Vertical Incision Subperiosteal Tunnel (VISTA) Technique

Drs. Su BCW, Chang CH, Roberts WE.

Abstract

Introduction: A 11 yr 1 mo male presented with a chief complaint (CC) of unerupted maxillary left canine (UL3).

Diagnosis: Bimaxillary protrusion (SNA 84, SNB 84) was associated with a full-cusp Class II Division 1 malocclusion with an overjet of 12mm and an overbite of 6mm (80%). This severe malocclusion was complicated by a horizontally impacted UL3 that was associated with substantial root resorption on the labial surfaces of both maxillary central incisors (UR1 and UL1). The discrepancy index (DI) was 36.

Etiology:The cause of the severe impaction was apparently a deviated path of eruption that may be related to inadequate space in the arch due to a relatively small UL primary canine.

Treatment:Phase I treatment began by placing Infrazygomatic crest (IZC) bone screws (BSs) bilaterally. The right IZC BS was used as anchorage for a VISTA submucosal procedure to retract the UL3 to its correct sagittal relationship in the arch, and then aligning it in the normal canine position. Once the UL3 was aligned, bilateral IZC anchorage was utilized to retract the entire maxillary arch to correct the full cusp Class II relationship. The occlusion terminating with the rst molars was nished with vertical elastics and fixed appliances were removed. The active treatment time was 31 months. Phase II treatment for six months was indicated to improve the nal alignment of the dentition after the second molars erupted. Final records were collected at the two year recall appointment.

Outcomes: The impacted UL3 was recovered and aligned in an ideal relationship. Phase I Cast-Radiograph Evaluation (CRE) was 36, due to major discrepancies in alignment and marginal ridges of the erupting 7s. After 6 months follow-up treatment, the nal CRE was 26.

Conclusions: Phase I treatment with the VISTA procedure was indicated to correct the impacted UL3 before it caused further root resorption of adjacent teeth. Phase II treatment is best delayed until the second molars are erupted. The VISTA approach for submucosal retraction of maxillary canine impactions is an ideal procedure for the critical esthetic zone. (J Digital Orthod 2018;50:52-71)

Key words:Insignia^®Impaction, impacted maxillary canine, vertical incision subperiosteal tunnel access, VISTA, infra-zygomatic crest, OBS
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Non-Extraction Treatment of Pseudo-Class III Anterior Cross-Bite Complicated
by Severe Crowding, Deep-Bite and Clenching

Drs. Hsu E, Chang CH, Roberts WE.

Abstract

Anterior cross-bite is a major esthetic and functional concern for patients and their parents. Based on the Lin 3-ring diagnosis, a 13 year-old boy was diagnosed as a pseudo-Class III malocclusion, associated with anterior cross-bite (overjet = -3mm), deep-bite (overbite = 8mm), severe crowding (-9/-2mm), concave pro le, and inadequate maxillary incisor exposure. There was an anterior functional shift on mandibular closure, and the mandible could be manipulated to an edge-to-edge incisal occlusion, when the condyles were positioned in centric relation. The Discrepancy Index (DI) was 23. A passive self-ligation appliance, bite turbos on lower rst molars, and early light short intermaxillary Class III elastics (ELSE) were used to correct this severe malocclusion in only 20 months. The Cast-Radiograph Evaluation (CRE) score was 23. At the nish, several morphologic features were noted that appear to re ect parafunction (clenching): relatively deep-bite, increased axial inclination ( aring) of the maxillary incisors, and the mandibular plane failed to open as expected. The ared maxillary incisors resulted in an unfavorable Pink & White dental esthetic score of 6. Long term follow up is indicated to control parafunction, open the bite, retract the maxillary incisors, and evaluate the potential for late mandibular growth to produce a skeletal Class III malocclusion. (J Digital Orthod 2018;50:78-94)

Key words:pseudo-Class III, non extraction, crowding, cross-bite, deep-bite, passive self-ligating appliance, parafunction, clenching
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