A Simple Technique Using a Modified Nance Appliance as Anchorage for Maxillary Molar Distalization—Two Case Reports

Chenshuang Li,Chun-Hsi Chung

doi:10.3390/app12020768

Abstract

Maxillary molar distalization to correct a dental Class II molar relationship and to create space to relieve crowding has been a long-lasting subject of debate in orthodontics. Generally, to distalize maxillary molars, an intra-arch distalization appliance is favored over an inter-arch appliance since it does not utilize mandibular dentition as an anchorage, so some unwanted side effects on mandibular incisors can be avoided. A variety of intra-arch appliances have been developed to distalize maxillary molars, such as the pendulum, Jones jig, first class appliance, distal jet, and modified C-palatal plate. Although they could achieve efficient molar distalization, the learning curve of proper appliance insertion and activation is relatively long. In addition, the appliances are not comfortable for the patients due to the bulky activation units, especially when the activation units are designed in the palatal area. The current manuscript describes a novel and effective maxillary intra-arch molar distalization appliance—a modified Nance appliance technique, which consists of: (1) palatally, a big acrylic button against the palatal rugae and connected to the premolars with wide mesh pads; (2) buccally, regular brackets on maxillary premolars and first molars with sectional round stainless steel archwires and open coil springs between the second premolar and first molar. Either bilateral or unilateral maxillary molar distalization can be achieved with this appliance, and the Class II elastics are not needed. It is simple to be fabricated, delivered, and activated, and it is comfortable for patients.

Highlights

Tooth size arch-length discrepancy is common in orthodontic treatment [1]
Based on the location of the anchorage, the maxillary molar distalization strategies can be classified into (1) inter-arch mechanics, which engages the mandibular dentition as the anchorage unit [5], and (2) intra-arch mechanics, which utilizes the support from the cranium, the maxillary bony structure, or the rest of the maxillary dentition [3]
All the inter-arch strategies may cause mandibular dentition mesialization and mandibular incisor proclination, which is unfavorable for patients who already presented with proclined mandibular anterior teeth and thin phenotype gingival tissue

Summary

Introduction

Tooth size arch-length discrepancy is common in orthodontic treatment [1]. For minimal to moderate amounts of crowding or incisor proclination in the maxilla of a Class II malocclusion, the distalization of molars is often used to avoid extraction [2]. The headgear’s efficiency depends on the patient’s compliance [15] To address this issue, a variety of intra-arch strategies have been developed in the past two decades, such as the pendulum [16], Jones jig [17], first class appliance [18], distal jet [19], modified C-palatal plate with the support of mid-palatal temporary anchorage devices (TADs) [20], as well as power chain or nickel-titanium (NiTi) coil connected with buccal alveolar TADs [21].

Appliance Design and Activation

Clinical Case Demonstrations

Conclusions