The lingual orthodontic technique, which is invisible to most during the treatment phase, attracts patients who are concerned about the unaesthetic appearance of brackets and wires. In contrast to the conventional multibracket labial system, the lingual technique implies that brackets are bonded onto the lingual surface of the teeth.

Lingual orthodontics was introduced in the 1970s by Dr. Kinya Fujita in Japan. Since then, it has evolved with many changes, including numerous modifications in the bracket design, upgraded laboratory techniques, simplified protocols, efficient biomechanics and clinical expertise. Considering the difference in lingual surface anatomy, lingual arch form, lingual arch perimeter, point of force application and altered biomechanics, clinical accessibility and ergonomics, practising lingual orthodontics requires a thorough understanding of a completely different concept than conventional labial mechanics. The advantages and disadvantages of the lingual appliance technique are presented in Table 58.1 .

Although the use of lingual orthodontic appliances can be traced to the 18th and 19th centuries ( Table 58.2 ), the first full arch multibracket lingual system was introduced in the 1970s by Dr. Kinya Fujita in Japan. Interestingly, he conceptualised the lingual appliance to address the risk of trauma to the lip and cheek from the possible impact on labial brackets in children practising martial arts and not for aesthetic reasons. In 1967, he presented his ideas on lingual orthodontics, started researching in 1971 and introduced the Fujita method in 1978. This method treated Class I and Class II cases by extracting four bicuspids. The Fujita bracket had three slots, namely occlusal, horizontal and vertical, and these were patented in July 1980.

During the same era, Craven Kurz, an American orthodontist, started his investigations with Jim Mulick in 1975, using plastic brackets bonded to the lingual tooth surfaces. He developed the first generation of the Kurz lingual bracket along with engineers Craig Andreiko and Frank Miller.

Subsequently, Ormco Task Force (Ormco, Sybron Dental Specialties, 1717 West Collins Ave, Orange, CA 92867) was formed in 1980 to continue the research and study in this field. The Kurz lingual bracket evolved from generation to generation and reached seventh generation Ormco Lingual Brackets in 1990, which became famous worldwide. The principal characteristics of this bracket were a bite plane, a base pad adapted to the anatomic features of the lingual surfaces of the teeth, and a pre-angulated slot according to the conversion of the torque used on the labial surface.

In 1984, Ormco launched the Torque Angulation Reference Guide (TARG) machine along with newer brackets. This machine is an essential aid to the laboratory technique for customising the brackets. As the years went by, newer bracket systems, customisation devices and laboratory techniques were introduced, all claiming better clinical results. Consequently, several professional societies were formed to provide scientific exchange and knowledge-sharing platforms. Table 58.3 presents some landmark events in the evolution and development of the lingual technique.

It is important to note that in the United States, after the initial development and expansion of lingual orthodontics in the 1990s, there was a sharp decline in the practice of this technique, probably due to the poor standard of completed cases attributed to inadequate training, and poorly developed laboratory systems. Thus, proper training and a steady learning curve are vital for excelling in lingual orthodontics.

The lingual orthodontic technique is conceptually different from the conventional labial technique under the following considerations:

• •

  Lingual anatomy: In contrast to the labial surface of teeth, lingual surfaces have fossa/grooves, cingulum, prominent marginal ridges and sometimes developmental anomalies like talon cusps ( Fig. 58.1 ) and the cusp of Carabelli. The incidence of morphological and developmental anomalies associated with the lingual surfaces of various teeth is presented in Table 58.4 . The variable lingual anatomy causes difficulty in the adaptation of a pre-fabricated factory-made bracket base. Furthermore, the cingulum in anterior teeth acts as an inclined plane that can produce significant changes in the orientation of the bracket slot (torque) with a change in vertical bracket positioning ( Fig. 58.2 ).

  

  Picture depicting variable lingual anatomy with talon cusp in 22 (A) , deep fossa in 11 and 21 (B) and shallow fossa in 12 (C) .

  TABLE 58.4

  Prevalence of anatomical anomalies in the lingual surface of the permanent dentition

  Developmental anomaly on lingual/palatal surface	Affected permanent teeth	Prevalence
  Dens invaginatus	Maxillary lateral incisors, followed by the central incisors	0.25%–7.7%
  Talon cusp	Maxillary lateral incisors	1.67%
  Shoveling	Maxillary lateral incisors Maxillary central incisors	5% 4%
  Cusp of Carabeli	Maxillary first molars	59%

  

  Lingual anatomy of tooth affects bracket slot orientation.

  Presence of cingulum on the lingual surface acts as an incline plane that leads to sharp change in the bracket slot orientation at different vertical positions. In contrast, the change on the labial side is less evident.

• •

  These difficulties are overcome by customising the brackets and transferring them to the lingual surfaces using an indirect bonding technique for the desired bracket prescription and accurate positioning.

• •

  Customisation of lingual brackets: Fabricating tooth surface-specific brackets by adding composite pads or metal bases to the stock brackets is called ‘customisation’. Customisation involves building in the bracket’s desired tip, torque and profile thickness. For example, to avoid first-order bends between the arch wire to accommodate six anterior teeth, the thickness (profile) of the composite pad is made such that the distance between the bracket slot and the labial surface of the tooth remains the same for all ( Fig. 58.3 ). Similarly, the premolar and molar (first and second molars) brackets are modified to avoid first-order bends between them. Different types of laboratory procedures to customise the lingual brackets are enumerated in Table 58.5 , and the classification of the customisation procedure in Table 58.6 .

  

  Customised backets of anterior teeth showing different thickness of composite pads between canines and incisors.

  This helps in omitting the first-order bends between them.

  TABLE 58.5

  Different laboratory procedures used for customisation of lingual brackets

  Year	Customisation procedure	Contributor
  1983	Custom Lingual Appliance Setup Service (CLASS system)	Fontanelle
  1984	Torque Angulation Reference Guide (TARG) system	Ormco Society
  1986	Bonding with Equal Specific Thickness (BEST) system	Dr. Didier Fillion
  1986	Slot machine	Dr. Thomas Creekmore
  1995	Simplified technique	Scuzzo and Takemoto
  1998	Hiro system	Toshiaki Hiro
  1999	Lingual Bracket Jig (LBJ)	Dr. Silvia Geron
  2003	Korean Indirect Bonding Set-up System (KIS)	Korean Society of Lingual Orthodontics
  	Convertible resin core system
  	Hybrid core system	Matsuno
  2010	Orapix system	D. Fillion
  2013	Transfer Optimized Positioning (TOP/INCOGNITO i BRACES) system	Dirk Wiechmann
  2014	DTC Device (Das’s Tip Torque Thickness Customisation Device)	Surya Kanta Das

  TABLE 58.6

  Classification of customisation of lingual bracket

  1. Customisation on therapeutic set-up models	2. Customisation on the malocclusion model using specialised devices (e.g. TAD-BPD machine, DTC device, BEST, Slot machine, ABP, LBJ)	3. Free hand customisation by visual understanding and projection (CVUP, e.g. simplified technique. In this technique only customised tip and adaptation of base can be achieved but toque and thickness cannot be controlled)
  a) Customisation on manual setup without any special devices: e.g. Hiro system and convertible resin core system
  b) Customisation on manual setup with special devices: e.g. CLASS system, Ray system, KIS system and Incognito system that uses manual setup, digital three-dimensional imaging and wire-bending robot
  c) Customisation on virtual (digital) setup model: e.g. Orapix system

  Only gold members can continue reading. Log In or Register to continue

  Share this:

  • Click to share on Twitter (Opens in new window)
  • Click to share on Facebook (Opens in new window)

  Related

  Related posts:

  1. Psychological implications of malocclusion and orthodontic treatment
  2. Limits of orthodontic treatment modalities: 3D perspective
  3. Digital and computerised cephalometrics
  4. 2D cephalometrics for orthognathic surgery
  5. Role of removable appliances in contemporary orthodontics
  6. Dentofacial orthopaedics for class II malocclusion with vertical maxillary excess in growing children

  

  Stay updated, free dental videos. Join our Telegram channel

  Join