Conservative Correction of Severe Skeletal Class III Open Bite: 3 Force Vectors to Reverse the Dysplasia by Retracting and Rotating the Entire Lower Arch
Shih YH, Lin JJ, Roberts WE.
Conservative treatment (without orthognathic surgery or extractions) of severe malocclusions limits cost, morbidity and surgical complications. A twelve year history (12-24yr) for a male with a developing Class III openbite malocclusion involved conventional treatment (12-14yr), relapse (18yr), and conservative treatment (21-24yr). Cephalometric superimpositions (18-21yr) revealed a clockwise rotation of the mandibular arch with molar extrusion was the principal growth aberration contributing to the severe malocclusion (Discrepancy Index 89). Posterior skeletal (miniscrew) anchorage with a passive self-ligating (PSL) appliance reversed the etiology of the malocclusion by retracting, intruding and distally rotating the entire lower arch. Speci c bracket torque selections and repositioning as needed delivered an excellent nal alignment (Cast-Radiograph score of 12). The moment to force ratio (M:F) for the line of force, relative to the center of resistance (CR) of the lower arch, determines the amount of molar retraction and intrusion. Miniscrews provide extra-alveolar (E-A) or inter-radicular (I-R) anchorage in both arches. Three miniscrew positions are proposed to retract and rotate the lower arch: 1. mandibular buccal shelf (MBS) (E-A), 2. distal to the lower first molar root (I-R), and 3. infra-zygomatic crest (IZC) (E-A). All three sites effectively retract and rotate the lower arch, but the I-R miniscrews interfere with the path of tooth movement, and the IZC screws fail to intrude the molars. Conclusions are: 1. MBS miniscrews produce an optimal line of E-A force for conservatively treating Class III openbite malocclusions to decrease lower facial height (LFH), and 2. reversing the etiology of a dentofacial dysplasia is an e ective strategy for predicable conservative treatment.
Key words:Class III, anterior open bite, temporary anchorage devices (TADs), mandibular buccal shelf (MBS) miniscrews, infrazygomatic crest (IZC) miniscrews, decreasing lower face height (LFH), forward rotation of the mandible
Interdisciplinary Treatment for a Mutilated Malocclusion with Excessive Vertical Dimension and Bimaxillary Protrusion
Chang HW, Chang CH, Roberts WE.
This case report describes the diagnosis and interdisciplinary treatment for an adult female with a mutilated (4 missing teeth), acquired malocclusion with a protrusive profile. The Discrepancy Index (DI) was 26. There were multiple residual root tips in the edentulous spaces of the upper arch, and a compromised lower 3-unit fixed prosthesis. The lower dental midline was deviated to the right side ~3mm but there was no functional shift. The bimaxillary protrusion was corrected by closing space in both arches utilizing OrthoBoneScrew® anchorage. An edentulous site was prepared to restore the upper left 2nd premolar ( #13) with an implant- supported prosthesis. Following orthodontics treatment, periodontal surgery was performed to correct soft tissue relationships in the maxillary anterior segment. Tooth #13 (UL 2nd premolar) was restored with an implant-supported prosthesis. The nal outcome for the malocclusion was very good as documented by a Cast-Radiograph Evaluation (CRE) score of 26, and an excellent Pink & White dental esthetic score of 1. (Int J Othod Implantol 2015;38:22-48)
Key words:bimaxillary protrusion, passive self-ligating appliance, periodontal surgery, osteoplasty, ostectomy, apless implant surgery, implant-supported prosthesis, IZC&buccal; shelf screws
Correction of a Full Cusp Class II Malocclusion and Palatal Impingement with Intermaxillary Elastics
Tseng L, Chang CH, Roberts WE.
A 13yr 5mo old female presented with a bilateral full cusp, Class II malocclusion, large overjet, deep curve of Spee and palatal impingement. A passive self-ligating appliance, with maxillary anterior bite turbos, was used as a platform for the application of an array of intermaxillary elastics. The severe Class II malocclusion, Discrepancy Index (DI) of 25, was conservatively corrected in 18 months to an excellent result, as documented with a Cast Radiograph Evaluation (CRE) of 21 and a Pink & White (P&W) dental esthetics score of 3. (Int J Othod Implantol 2015;38:54-72)
Key words:large overjet, palatal impingement, bite turbos, early light short elastics, Class II orthodontic mechanics, finishing elastics, residual Class II relationship
Missing Maxillary Central Incisor Treated with Mesial Substitution of the Lateral Incisor, Canine and First Premolar
Huang TK, Chang CH, Roberts WE.
A 24 yr female presented with convex pro le, everted lower lip, severe lip protrusion, bimaxillary skeletal protrusion, ared maxillary incisors and two missing teeth: maxillary left central incisor and mandibular right rst molar. The missing upper central incisor was corrected with progressive mesial substitution of the lateral incisor, canine, and first premolar. On the contralateral side, the left maxillary rst premolar was extracted, and the space was closed to achieve a balanced retraction of the maxillary anterior segment to correct the dental and soft tissue protrusion. The mandibular right molar space was closed, the patient’s facial pro le was signi cantly improved, and dental esthetics in the esthetic zone were detailed with restorative procedures. This very di cult malocclusion, with a Discrepancy Index (DI) of 38, was treated to a satisfactory Cast Radiograph Evaluation (CRE) of 27, and a Pink and White (P&W) dental esthetics score of 6. The total interdisciplinary treatment time was 35 months.(Int J Othod Implantol 2015;38:78-93)
Key words: Bimaxillary protrusion, missing maxillary central incisor, missing mandibular first molar, dental substitution, asymmetry, restorative compensation