Effects of Herbst Appliance Treatment on the Mandibular Incisor Segment: a Three-Dimensionally Analysis

Three-dimensionally evaluation of the treatment changes of a Herbst appliance using a lower anchorage unit not touching the lingual surface of the lower incisors. The sample consisted of 23 Class II:1 patients (12 males, 11 females) with a mean age of 15.7±1.7 years treated with a Flip-Lock Herbst® appliance (TP Orthodontics, Inc., La Porte, IN, USA). The lower anchorage unit for the Herbst appliance consisted of two anchor bands connected by a lingual arch with 3mm distance from the incisor’s lingual surface. Treatment changes in mandibular incisor inclination, overjet and overbite were evaluated by means of cone beam computed tomography images (i-CAT® Classic unit, Imaging Sciences International, Hatfield, PA, USA) obtained before and after treatment with the Herbst appliance. On average, there was a statistically significant increase in mandibular incisor inclination (2.6+1.8°) and a reduction in overjet (3.2+2.2mm) and overbite (1.3+0.9mm). Genders did not differ significantly. Incisor proclination was however only seen in 74% of the patients. The changes in mandibular incisor inclination were associated with the changes in overjet (/r/ = 0.1 to 0.5) and overbite (/r/ = 0.3 to 0.7). A Herbst appliance with a mandibular anchorage unit distant from the incisor’s lingual surface results in smaller amounts of mandibular incisor proclination compared to literature. However, as it induces canine anchorage loss, the decreased amount of proclination may not prevail after multibracket treatment. Keywords: Cone-Beam Computed Tomography. Mandibular Advancement. Tooth Movement Techniques. ResumoAvaliação tridimensional das alterações induzidas pelo aparelho Herbst utilizando a unidade de ancoragem inferior afastada da superfície lingual dos incisivos. A amostra incluiu 23 pacientes Classe II:1 (12 masculino, 11 feminino), média de idade 15,7 ± 1,7, tratados com aparelho Herbst Flip-Lock® (TP Orthodontics, Inc., La Porte, IN, EUA). A unidade de ancoragem inferior do aparelho Herbst consistiu-se de duas bandas conectadas por um arco lingual afastado 3mm da superfície lingual do incisivo. As alterações induzidas pelo tratamento na inclinação dos incisivos inferiores, trespasse horizontal e trespasse vertical foram avaliadas por meio de imagens de tomografias computadorizadas de feixe cônico (i-CAT® Classic unit, Imaging Sciences International, Hatfield, PA, USA) obtidas antes e após o tratamento com aparelho Herbst. Na média, houve diferença significativa com aumento da inclinação dos incisivos inferiores (2,6+1,8°) e diminuição do trespasse horizontal (3,2+2,2mm) e do trespasse vertical (1,3+0,9mm). Não houve diferença estatística entre os sexos. No entanto, a vestibularização do incisivo ocorreu em apenas 74% dos pacientes. As alterações na inclinação dos incisivos inferiores apresentam correlação estatisticamente significativa com as alterações no trepasse horizontal (/r/ = 0,1 a 0,5) e no trespasse vertical (/r/ = 0,3 a 0,7). O aparelho Herbst com uma unidade de ancoragem inferior afastada da superfície lingual dos incisivos resulta em menor quantidade de vestibularização do incisivo inferior em comparação com a literatura. Entretanto, como isto induz perda de ancoragem do canino, a diminuição da vestibularização pode não prevalecer ao final tratamento ortodôntico com braquetes. Palavras-chave: Tomografia Computadorizada de Feixe Cônico. Avanço Mandibular. Técnicas de Movimentação Dentária.

Pharyngeal Airway Volume in Class II Patients Treated with Herbst and Fixed Mechanotherapy Using Cone Beam Computed Tomography - A Comparative Study from Haryana, India

BACKGROUND Skeletal malocclusions occur because of the defect in the underlying skeletal structure. Mandibular skeletal retrusion is the most common characteristic of class II malocclusion. The purpose of this study was to evaluate pharyngeal airway dimension in Class II patients treated with Herbst appliance and fixed mechanotherapy using cone beam computed tomography (CBCT). METHODS This comparative study was conducted among 30 Class II patients (9 to 15 years of age) selected from the outpatient department of orthopaedics. They were divided into 2 Groups; Group I (15 patients) was treated by Herbst appliance; Group II (15 patients) was treated by fixed mechanotherapy. Pharyngeal airway volume, length and width evaluation were done using CBCT in vivo dental software 5.1 (ANATOMAGE, San Jose, CA). Intergroup comparison was done using independent t tests and level of significance (P < 0.05). Correlation of parameters were carried out using Pearson’s correlation test. RESULTS Significant increase in nasopharyngeal, velopharyngeal, glossopharyngeal, laryngopharyngeal, and total airway volume in Herbst group was observed. Velopharyngeal length, glossopharyngeal length and nasopharyngeal airway width showed significant increase in Herbst group. CONCLUSIONS Treatment of Class II patients with Herbst appliance resulted in increase in pharyngeal airway volume. Herbst therapy induced repositioning of tongue resulting in increased length due to posterior fall of uvula, and hence airway volume increased drastically. KEY WORDS Airway Volume, Herbst Appliance, Class II Malocclusion, Retrognathic Mandible

Herbst Appliance palatally anchored in the treatment of dental class II malocclusion

In this case report, Authors describe the correction of a class II malocclusion using only an Herbst appliance palatally anchored with miniscrews. Before sagittal correction in the same appliance we applied a palatal screw to obtain maxillary expansion. The device were removed after 12 months of treatment. The final result included the correction of Class II malocclusion by lower dentoalveolar compensation mainly. The lip function favorite the spontaneous correction of upper frontal torque with consequent improvement of facial esthetics. After a follow up of 12 months the clinical result is satisfactory in terms of occlusion and esthetics. This clinical case showed a simple orthopedic and dentoalveolar approach to correct transversal discrepancy, dental class II malocclusion and also frontal proclination only with one appliance in a very short treatment time.

Skeletal and dental changes induced by the Flip-Lock Herbst appliance in the treatment of Angle’s class II division 1 malocclusion during active growth period: A preliminary study

Background. The Flip-Lock Herbst (TP Orthodontics Inc.) is a fixed functional appliance, a variant of the Herbst appliance, introduced by Miller. It is claimed to have better patient tolerance due to its increased freedom for the mandible’s lateral movements. There have been no studies on the flip lock Herbst till date. This study was undertaken to assess the efficiency of the Flip-Lock Herbst appliance in correcting Angle’s class II division 1 malocclusion. Methods. Eight subjects in their active growth period with class II division 1 malocclusion due to a retrognathic mandible were included in the study. Standardized lateral cephalometric radiographs were used to evaluate skeletal and dental changes with the SO analysis. Paired samples t-test was used to assess statistical significance. Results. Statistically significant increases in mandibular length (pg/OLp) and effective mandibular length (ar/OLp + pg/OLp) were observed. There was a significant maxillary restraining effect. Dental effects were significant and exhibited class II correction features except for the position of lower incisors within the mandible (ii/OLp - pg/OLp). Skeletal changes accounted for 61% and dental changes for 39% of the total treatment for molar correction. For overjet correction, skeletal changes contributed to 63% and dental changes to 37% of the total treatment. Conclusion. The Flip-Lock Herbst appliance was efficient in correcting Angle’s class II division 1 malocclusion due to a retrognathic mandible. Both skeletal and dental changes were evident, with the former predominating (60:40).