Assessing the Effectiveness of Chin-Cup Therapy in the Treatment of Developing Class 3 Malocclusions

Abstract

Background: Mandibular prognathism in Class 3 malocclusion (CLIII) is one of the most severe maxillofacial deformities. Fortunately, most of this malocclusion cases can be treated by facial growth modification, using extra and/or intra-oral appliances in growing individuals. Occipital-pull chin cup is the extra-oral orthopaedic appliance, which was mostly used for the treatment of mandibular prognathism in growing Class 3 1(Ngan, Sung, 2015). Unjustifiably, most orthodontists I know do not use chin cup therapy in the treatment of CLIII. Therefore, being new to the field of orthodontics, I needed to build a highly evidenced based knowledge on chin cup therapy’s effectiveness in the treatment of developing CLIII with prognathic mandible. Objective: Through a narrative literature review, the aim of the study was assessed following scientific methodology. Articles published from January 2010- November 2020 (commencement of the current review) were collected using keywords derived from PICO. Only highly evidence based studies (randomised and non-randomised clinical trials) with the least risk of bias scores were selected, and critically appraised using the Critical Appraisal Skill Programme (CASP). Results were used to draw the conclusion. Material and Method: The study title was broken down into its PICO (population, intervention, comparative, outcome) components and search keywords were derived. These were used to carry out a literature search through electronic search engines (Medline-PUBMED, Science Direct, ISI Web of Knowledge, Research gate, Google Scholar, Cochrane library and hand searching of references list. Collected articles were assessed for risk of bias using Downs and Black (D&B) scale. Papers with score ‘good’ and above’ on the D&B assessment were critically appraised. PRISMA statement reporting format and Harvard referencing system were adopted in the study. Result: Following the Downs and Black assessment only 4 studies were found at a level worthy to be critically appraised. Results of all the four articles revealed that chin cup therapy produced significant growth modification in the mandible, when applied at an early age. Moreover, chin cup was also found to increase the lower anterior facial height significantly. All the papers considered only the short-term effect of chin cup, but not the long-term effect. Treatment results stability was also not reported. Conclusion: The significant improvement in CLIII manifestation in the selected articles, make it possible to conclude that chin cup is viable for the treatment of CLIII malocclusion with mandibular prognatism. However, treatment results stability needs to be researched.