Comparison of effects of monoblock and Herbst appliances by different vertical growth patterns

Objective: The aim of this study is to compare the effects of monoblock and Herbst appliances applied on skeletal, dental and soft tissues in Class II anomalies with different vertical growth patterns and different developmental stages. Method: The records of 302 patients with mandibular retrognathia who applied to Akdeniz University Faculty of Dentistry Orthodontic Clinic and received functional treatment between 2012 and 2018 were analyzed. Among these patients, 80 monoblock and 31 Herbst appliance applied patients were determined according to the inclusion criteria. A total of six groups were formed by determining the developmental periods and vertical growth patterns of the patients whose wrist-wrist and lateral cephalometric films were examined. Monoblock peak group (MP; 27 normodivergent, 15 hypodivergent), monoblock postpeak group (MPP; 19 normodivergent, 19 hypodivergent), and Herbst postpeak group (HPP; 17 normodivergent, 14 hypodivergent). Intragroup changes in cephalometric measurements were performed by paired t-test, One-way ANOVA test was used to compare intergroup changes. Results: While a limiting effect on the maxilla was observed in the HPP, MP and MPP groups, statistically significant increases were observed in the parameters showing the sagittal growth in the mandible. The increase in SNBo, Co-Gn(mm) and Co-Go(mm) parameters was observed the most in the MP group. Statistically significant increases was found in lower incisor parameters. The group in which lower incisor protrusion was observed the most was determined as HPP; this difference is significant between groups. Perpendicular plane angles were similar between hypodivergent and normodivergent groups. FMAo angle increased statistically more in hypodivergent groups. Conclusion: Similar and effective results were obtained with the use of Herbst and monoblock appliances in different growth periods. Lower incisor protrusion was highest in the Herbst group. The difference in hypodivergent groups was mostly observed in the plane angles of the upper incisors. Key words: mandibular retrognathia, monoblock, Herbst appliance, hypodivergent