Mutilated Class III Malocclusion with Anterior Crossbite and Autotransplantation of Two Molars

Drs. Chang MJ, Kuo PJ, Lin JJ, Roberts WE.

Abstract

Introduction: A 20-year-old female presented for orthodontic consultation to evaluate chief complaints of multiple caries, lower arch spacing and a protrusive lower lip.

Diagnosis: Clinical and radiographic examination revealed a straight facial profile (G-Sn-Pg’ 3˚), protrusive lower lip, hypermentalis activity, lower dental midline deviated to the left, asymmetric Class III/I subdivision-right malocclusion, wide arches, 6mm of space in the lower arch, and a relatively high mandibular plane angle (SN-MP 45˚). Panoramic radiography revealed a hopeless UR6, missing LL7 and an endodontically-treated LL6 with periapical sclerosis. The Discrepancy Index was 54 points.

Treatment: A passive self-ligating appliance was installed to align the dentition and prepare implant sites. Two teeth (UR6, LL6) were subsequently extracted and the sites were immediately transplanted with the LR7 and UL8, respectively. A mandibular buccal shelf (MBS) bone screw (BS) was placed mesial to the LR8 for anchorage to retract the lower right segment to close space and correct the dental midline. Lower buccal segments were differentially retracted with BS anchorage and Class III elastics to correct the asymmetric Class III interdigitation. Third order correction and finishing were accomplished with rectangular archwires and a root torquing auxiliary. The active treatment time was 38 months.

Outcomes: Excellent dental and periodontal results were achieved. Cast-Radiograph Evaluation was 27 and the Pink & White Esthetic Score was 2. Lip protrusion and incompetence were corrected to the patient’s satisfaction. The lower lip was retracted and lower facial height increased. The facial changes reflected an undiagnosed functional shift in occlusion, extruded lower molars, a 2˚ clockwise rotation of the mandibular plane, as well as retraction and extrusion of the lower incisors.

Conclusions: Autogenous molar transplantation is a cost-effective option for correction of a complex, mutilated malocclusion. It is important to carefully assess functional shifts in occlusion particularly if there are wear facets on the teeth. (J Digital Orthod 2019;54:4-23)

Key words: Class III, mutilated malocclusion, passive self-ligating appliance, buccal shelf miniscrew, dental transplantation, anterior crossbite, interdisciplinary treatment, midline deviation
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VISTA and 3D OBS Lever-Arm to Recover a 
Labially-Impacted Canine: Differential Biomechanics to Control Root Resorption

Drs. Lin JH, Chang CH, Roberts WE.

Abstract

History: A 15-year-old female presented with a chief complaint (CC) of unesthetic smile and protrusive lips.

Diagnosis: Lower facial height and convexity were within normal limits (WNL), but the lower lip was protrusive (3mm to the E-Line). Bimaxillary retrusion (SNA 79.5˚, SNB 76˚, ANB 3.5˚) and a high mandibular angle (SN-MP 38˚) were noted. Lower incisors were prominent (L1 to MP 96˚, L1 to NB 8mm). Molars were Class I, but the UR3 was Class II. The upper left deciduous canine (ULc) was retained, and the UL3 was labially impacted. An oblique direction of canine eruption wedged the impaction between the keratinized mucosa and the adjacent incisor, eliciting root resorption on the labial surface of the UL2. The Discrepancy Index (DI) was 16.

Treatment: Following extraction of all four first premolars and the ULc, all teeth except the UL2 were bonded with a Damon Q® passive self-ligating (PSL) bracket system. VISTA (Vertical Incision Subperiosteal Tunnel Access) technique was performed to produce a submucosal space for retraction and extrusion of the impacted UR3. A button was bonded on the UL3, and a power chain was attached. The elastomer chain exited the mucosa through a more distal incision, and traction was applied with a custom lever-arm, anchored by an OBS® inserted into the left infrazygomatic crest (IZC). The impaction was retracted into a normal position between the UL2 and UL4. Once the UL3 was extruded to the occlusal plane, the UL2 was bonded and its axial inclination was corrected with a labial root torquing auxiliary. Both arches were detailed and finished.

Outcomes:After 24 months of active treatment, the UL3 was well aligned, but the labial gingiva supporting it was immature and only partially keratinized. Follow-up visit 1.5 years later showed its maturation into a stable but relatively thin band of gingiva. In retrospect, this UL3 gingival problem may have been avoided by adjusting the 3D lever-arm for a more palatal emersion of the impaction. There was no change in the preexisting labial root resorption of the UL2, but no additional root resorption on any teeth occurred during active treatment. Final alignment and dental esthetics were excellent as evidenced by an ABO Cast-Radiograph Evaluation (CRE) score of 12, and the IBOI Pink & White Esthetic Score of 2.

Conclusion:VISTA with an OBS 3D lever-arm is an important advance for orthodontic impaction recovery. Submucosal retraction of a labially-impacted, partially transposed maxillary canine permits optimal emergence into the arch. Differential biomechanics of soft and hard tissue explains impaction-related root loss prior to treatment, as well as the mechanism for protecting an unrestrained lateral incisor while the impacted canine is recovered. (First printed in APOS Trends Orthod 2019;9(1):7-18. Reprinted with permission. J Digital Orthod 2019;54:28-48).

Key words: Impacted maxillary canine, vertical incision subperiosteal tunnel access (VISTA), bone screw anchorage, root resorption, differential biomechanics, follicle, dental sac, tooth movement, eruptive force
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Probable Airway Etiology for Skeletal Class III Openbite Malocclusion with Posterior Crossbite: Camouflage Treatment with Extractions

Drs. Chen CH, Chang CH, Roberts WE.

Abstract

History: A 27-year-old male presented for orthodontic consultation with a chief complaint (CC): front teeth do not contact. Upper right canine (UR3*) was previously extracted to alleviate maxillary crowding. Previous doctors suggested orthognathic surgery, but the patient was concerned about the cost and morbidity. Beethoven Orthodontic Clinic was consulted because of the reputation for managing skeletal openbite malocclusion conservatively.

Etiology: A childhood airway problem, probably related to enlarged pharyngeal lymphoid tissue, resulted in anterior posturing of the mandible and low tongue posture to open the airway. The patient is now able to breath through the nose with the mouth closed. Orthodontic correction of the malocclusion is expected to spontaneously resolve the low tongue posture which is the proximal cause of the anterior openbite and posterior crossbite.

Diagnosis:Skeletal (SNA 83˚, SNB 86˚, ANB -3˚) Class III malocclusion (10mm bilaterally) was combined with 6mm anterior openbite and bilateral posterior crossbite. The UR3 was missing and the maxillary midline was deviated 3mm to the right. The patient could breathe normally through the nose with the lips closed. The Discrepancy Index (DI) for this severe skeletal malocclusion was 103.

Treatment:Instruction and reinforcement of normal tongue posture is emphasized throughout treatment. Correct crowding and establish symmetry for the missing UR3 by extracting UL4, UR4, and LL4. Resolve the posterior crossbite with rapid palatal expansion of the maxillary arch, followed by cross elastics. Install a full fixed appliance with passive self-ligating brackets. Utilize standard torque for upper anteriors and super-high torque for lower anteriors. Supplement the torque correction in the lower anterior segment with an archwire sequence of 0.016x0.025-in 34mm with 20˚ Pre-Torque CuNiTi, and 0.016x0.025-in stainless steel with 3rd order bends. Follow-up with torquing auxiliary springs as needed.

Results:After 33 months of active treatment, this severe skeletal malocclusion was conservatively corrected to a near ideal Class I occlusion without orthognathic surgery or temporary anchorage devices (TADs). The Cast Radiograph Evaluation (CRE) was 22 points, and Pink & White dental esthetics score was 0.

Conclusion:Severe Class III openbite malocclusion may result from airway-related anterior positioning of the mandible and low tongue posture during childhood. Conservative correction with extractions and differential space closure is indicated, if the patient is able to breathe normally through the nose with the mouth closed. Spontaneous correction of the aberrant postural habits is probable when the malocclusion is corrected. Otherwise, specific habit correction therapy is indicated. (J Digital Orthod 2019;54:54-76)

Key words: Class III malocclusion, anterior crossbite, anterior open-bite, posterior cross-bite, etiology, childhood airway insufficiency, pharyngeal lymphoid tissue, torque selection
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Introduction to Invisalign® Smart Technology: Attachments Design, and Recall-Checks

Drs. Chang MJ, Chen CH, Chang CY, Lin JSY, Chang CH, Roberts WE.

Abstract

Modern clear aligners are engineered to expand the boundaries for the utilization of removable appliances to treat a wide variety of malocclusions. Innovation is continually evolving to provide orthodontists with greater control of tooth movement to achieve desired outcomes. Three current technologies are SmartTrack, SmartForce, and SmartStage. Attachment design is an important aspect of ClinCheck. There are 5 questions that provide guide lines for choosing attachments. Two examples are presented to demonstrate the design of dental attachments to facilitate tooth movement. Invisalign G6 is a method for treating patients with extractions, particularly first premolars. It provides vertical and second order (root parallelism) control for predictable outcomes with maximum or moderate anchorage. Efficient management of space closure is an important aspect for aligner therapy because enamel stripping and extractions are common approaches for managing crowding and protrusion. At every appointment it is important to check aligner adaptation (fit), attachment positions, and anchorage preparation. This article reviews clinical procedures for numerous applications and also addresses clinical problems. (J Digital Orthod 2019;54:80-95)

Key words: Invisalign clear aligners, ClinCheck software, SmartForce features, SmartTrack material, SmartStage, Attachment design, Invisalign G6, Aligner fit, TADs, CII elastics
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Clinical Tip for Simultaneously Uprighting and Rotating Lower Molars

Drs. Tseng L, Chang CH, Roberts WE

When a lower first molar is missing, the second molar usually tips into the space and may incline lingually. If the treatment plan is to move the right second and third molars mesially to close a missing first molar space, a rotation of the third molar complicates bonding procedures and mechanics application. This article describes an effective method for simultaneously uprighting and rotating molars utilizing a bonded button and the elastic properties of a resilient archwire. ………

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