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4/20/16 Does Class II malocclusion deserve “Early treatment” ?? Herbst appliance treatment: what we have learned Bernardo Souki DDS, MsD, PhD Class II vs. Early treatment Dentoskeletal effects Special indications for Class II Early treatment Psychosocial effects “Early treatment should not be thought of as an effective and efficient way to treat most Class II children.” “The decision for Class II early treatment should be based on Pre-treatment special indications for each child.” Post-treatment with Headgear Special indications for Class II Early treatment Psychosocial effects Special indications for Class II Early treatment Risk of traumatic injury “Early orthodontic treatment for Class II/1 malocclusion results in higher self-concept scores and fewer negative social experiences.” O`Brien et al., 2003 1 4/20/16 Class II vs. Early treatment Class II vs. Early treatment Risk of traumatic injury Risk of traumatic injury • Overjet ≥5mm “Providing early orthodontic treatment PEDIR FOTO MARIA ILMA for children with prominent upper front teeth is more effective in reducing the incidence of incisal trauma than providing one course of orthodontic treatment when the child is in the early adolescence.” Thiruvenkatachari et al., 2014 Class II vs. Early treatment Risk of traumatic injury • Overjet ≥5mm • Lip incompetence ld be the But, when wou treat to g in ideal tim ???? II ss la C al skelet 2 4/20/16 Class II dentofacial orthopedics Class II vs. Early treatment Ideal timing Peak in Mandibular Growth Summary Primary CS 1 CS 2 CS 3 CS 4 CS 5 Early mixed Intertransitory CS 6 Class II vs. Early treatment Summary Late mixed dentition One-phase Class II treatment associated with fixed appliance One-phase Class II treatment associated with fixed appliance Advantages 1. Effectiveness: >2 mm mandibular growth 2. Efficiency: Shorter total duration 3. Stability: Ideal intercuspation 3 4/20/16 How to treat al effectively skelet n??? io us cl oc Class II mal Skeletal Class II malocclusion How to treat? ü Facial convexity is not bad ü Risk of trauma is not too big ü No psychosocial problems ü Extensive growth potential forecast ial convexity is What if the fac O mpliance is TO co the , big O TO sidual growth re the or , all sm o long??? phase is NOT to 4 4/20/16 Class II malocclusion Herbst appliance The Herbst appliance is the most frequently used mandibular advancement device in the USA. Emil Herbst’s original appliance (1910) von Bremen, Pancherz, Ruf, 2007 Pancherz, 1979 Silva et al., 2015 Skeletal Class II malocclusion Mandibular deficiency Retrusion of the mandible is the most commonly occurring factor contributing to skeletal Class II malocclusion Renfroe, 1948 McNamara Jr., 1981 Buschang & Martins, 1998 Pancherz & Ruf, 2008 5 4/20/16 Herbst appliance Benefits of Herbst appliance Immediate benefits • • • • Expedite improvement of the self-esteem Reduce the risk of incisor trauma Less reliance on patient compliance Shorter treatment duration Patients & Methods Skeletal Class II patients (n=50) Pubertal stage (CS3 – CS4) Ethics approval from IRB Herbst appliance treatment effects 3D assessment study Patients & Methods Patients & Methods Herbst group Sampling design 50 skeletal Class II growing patients One-step full activation Herbst Group n = 25 Comparison Group n = 25 Age: Age: 12y – 16y 12y – 16y CS3 – CS4 CS3 – CS4 Permanent den??on Permanent den??on 6 4/20/16 Patients & Methods Patients & Methods Comparison group Comparison group Marsupialization of cysts Previous alignment and leveling Patients & Methods Comparison group Patients & Methods Herbst appliance design Maxillary impacted canines Image analysis 3D virtual models What we have learned 7 4/20/16 What we have learned about Mandibular displacement a) Mandibular displacement b) Condylar growth c) Condylar displacement d) Glenoid fossa remodeling e) Dentoalveolar changes f) Maxillary adaptations Mandibular displacement Pre-treatment Herbst insertion 2 months 6 months Herbst removal 8 months of tx. Pre-treatment Facial balance improvement Herbst insertion Herbst removal T0 (Pre-treatment) T1 T2 (Herbst insertion) (Herbst removal) 8 4/20/16 Mandibular forward displacement vs. Facial improvement Diego – 16 y 8 mos. Herbst appliance T2 T0 Diego’s CBCT scans superimposition Relative to the cranial base T0 T1 10mm initial advancement after Herbst insertion T1 T2 Mandible moved back 6mm during Herbst treatment T2 T0 4mm effective mandibular advancement T0 – Pre-treatment T1 – Immediately after Herbst insertion T2 – After 8 mos. Herbst treatment Mandibular displacement (Superimposition at the cranial base) Herbst group Mandibular displacement Take home message ü Mean 65% of rebound during Herbst treatment (range 47% - 75%). ü 1.7 mm of effective mandibular forward displacement (5 mm of Herbst advancement ). ü Herbst appliance treatment improved the patient’s profile (short-term evaluation). Comparison group 9 4/20/16 3D superimposition at the body of the mandible Condylar growth Condylar growth Condylar growth (Regional Mandibular Superimposition) (Regional Mandibular Superimposition) Herbst group Herbst group Comparison group 1.9 mm - backward 0.7 mm - backward 2.5 mm - upward 1.6 mm - upward Herbst vs. Comparison Comparison group + 1.2mm (2x more) - backward + 0.9 mm (0.5x more) - upward -4.0 -2.0 0.0 2.0 3.0 4.0 Condylar growth Take home message Condylar displacement ü Effective backward condilar growth (1.2 mm). ü Change in the direction of condilar growth. 10 4/20/16 ? yle positioned Where is cond atment ??? tre t bs after Her ? ? ? ? Condylar displacement Condyle-Glenoid fossa relationship after Herbst removal 3D superimposition at the glenoid fossa Difference Herbst vs. Comparison groups X (RL) = 0.01 mm Y (AP) = 0.06 mm Z (IS) = 0.11 mm 3D = 0.07 mm Condylar displacement Take home message Glenoid fossa remodeling ü Regardless how much the condyle is moved forward and downward, it returned to its original relationship with the glenoid fossa. Herbst group Comparison group Superimposition at the anterior cranial fossa Pre-treatment Immediately after Herbst insertion Superimposition at the anterior cranial fossa 8 months after Herbst insertion Baseline 10 months after 11 4/20/16 Glenoid fossa remodeling Take home message ü ü Bone remodeling developed at the articulating surface of the glenoid fossa of Herbst patients. At this point it is not possible to determine that 8 months of Herbst treatment is sufficient to produce a stable new bone in the glenoid fossa. Dentoalveolar changes Molars Incisors Dentoalveolar changes Take home message ü Significant lower incisor proclination Mean 7.3 degrees (up to 21 degrees) ü Variable, but mostly small, upper incisor uprighting ü Maxillary molar 1.4 mm backward 0.4 mm upward (but maxilla moved 0.9 downward) ü Mandibular molar 1.1 mm forward 0.6 mm upward Maxillary changes Maxillary changes Take home message ü No significant skeletal SAGITAL and VERTICAL changes were observed. ü Essentially dentoalveolar movements (Headgear effect). 12