Mandibular retrognathia correction using a fixed sagittal guidance appliance individually manufactured by selective laser melting manufacturing technology

1.

Introduction

According to the National Health and Nutrition Estimates Survey III (NHANES III), Class II malocclusion occurs in 23 per cent of children, 15 per cent of youths and 13 per cent of adults (Proffit et al. , 2000). McNamara (1981) reported that the nature of the Class II malocclusion is not the result of a single component, but of a variety of different dental and skeletal combinations. Mandibular skeletal retrognathia is the most common characteristic of Class II malocclusion.

In recent years, reverse engineering (RE), computer-aided design (CAD), computer-aided manufacturing (CAM) and rapid prototyping (RP) have been used in medicine and dentistry (Gibson, 2005; Budak et al. , 2012). Diagnostic tools have become increasingly sophisticated, and medical imaging technology can now present patient data with high precision. Selective laser melting (SLM) is a layer-wise material addition technique that allows production of complex 3D parts by selectively melting successive layers of metal powder on top of each other, using the thermal energy supplied by a focused and computer-controlled laser beam (Kruth et al. , 2005a). SLM is highly suited for the production of medical and dental appliances owing to their individuality, complex shape and low volume (Kruth et al. , 2005b; Benazzi and Senck, 2011; Jevremovic et al ., 2011; Rotaru et al. , 2015).

A case of Class II malocclusion with retrognathic mandible, being successfully treated using a fixed sagittal guidance (FSG) appliance made by SLM, is presented.

2.

Materials and methods

2.1

Diagnosis

A 14-year-old boy with permanent dentition visited the Orthodontic Department with a basic complaint of "overbite and overlapping front teeth."

The extraoral clinical examination and facial photographs showed a short facial height, a convex profile due to the retrognathic mandible and a deep mentolabial fold (Figure 1). The intraoral examination (Figure 2) and pre-treatment study cast confirmed an overjet (8 mm), deep overbite (7 mm) and an accentuated lower curve of Spee. The midlines were coincident and the buccal segment relationship was Class II on both sides. The maxillary and mandibular arches were spaced. There was mild excess space in the maxillary and mandibular arch, 4 mm and 1.5 mm, respectively. The intraoral assessment found that oral hygiene was fair.

The panoramic radiograph showed that all teeth were present...