|Year : 2016 | Volume
| Issue : 5 | Page : 4-9
The current evidence and implications of lingual orthodontics
Pratap Saini1, Hema Sharma1, Anmol S Kalha2, Anil K Chandna3
1 Senior Lecturer, Department of Orthodontics and Dentofacial Orthopaedics, I.T.S Dental College, Hospital and Research Centre, Greater Noida, Uttar Pradesh, India
2 Senior Prof., Department of Orthodontics and Dentofacial Orthopaedics, I.T.S Dental College, Hospital and Research Centre, Greater Noida, Uttar Pradesh, India
3 Head and Prof., Department of Orthodontics and Dentofacial Orthopaedics, I.T.S Dental College, Hospital and Research Centre, Greater Noida, Uttar Pradesh, India
|Date of Submission||13-Dec-2016|
|Date of Acceptance||14-Dec-2016|
|Date of Web Publication||18-Jan-2017|
Dr. Pratap Saini
Department of Orthodontics and Dentofacial Orthopaedics, I.T.S Dental College, Hospital and Research Centre, Knowledge Park-III, Greater Noida - 201 310, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
The purpose of this review is to investigate the current evidence and implications of lingual orthodontics. The electronic database search was done on PubMed, Cochrane Library, Embase, EBSCOhost, Web of Knowledge, and Google Scholar reporting on appliance design, bonding, and laboratory setup, biomechanics, survey studies, case reports, and treatment outcomes to find the current evidence of lingual orthodontics. The evidence available on lingual orthodontics traces a very clear and predictable pattern. The 80's was devoted to the limitation and progression of the concept; the 90's to the comparison between labial and lingual and the evolution of laboratory technique and bracket system. The last decade focuses on innovations, the predictability of outcomes, the impact of white spot lesion, and the patient acceptability. This review also shows that biomechanical principles of lingual orthodontics are well understood and established today, any case that can be treated with labial orthodontic appliance, can also be treated effectively with lingual orthodontic appliance as the completely customized lingual appliance can provide predetermined treatment outcome.
Keywords: Adverse effects, appliance design, clinical outcome, current evidence, lingual orthodontics
|How to cite this article:|
Saini P, Sharma H, Kalha AS, Chandna AK. The current evidence and implications of lingual orthodontics. J Indian Orthod Soc 2016;50, Suppl S1:4-9
|How to cite this URL:|
Saini P, Sharma H, Kalha AS, Chandna AK. The current evidence and implications of lingual orthodontics. J Indian Orthod Soc [serial online] 2016 [cited 2018 Nov 14];50, Suppl S1:4-9. Available from: http://www.jios.in/text.asp?2016/50/5/4/198607
| Introduction|| |
The growing interest in lingual orthodontics is perhaps a reflection of the social and esthetic issues of orthodontics being addressed as more adults seek treatment. The issue remains confounded by the clinical manipulation of the appliance, the patient comfort, and the predictability of outcomes. For any technique or system to succeed, it must address the above three issues directly.
The evidence available on lingual orthodontics traces a very clear and predictable pattern. The 80's were devoted to the limitation and progression of the concept, the 90's to the comparison between labial and lingual, and the evolution of laboratory technique and bracket system. The last decade focuses on innovations, predictability of outcomes, the impact of white spot lesion (WSL), and the patient acceptability.
The purpose of this review is to investigate the current evidence and implications of lingual orthodontics. The electronic database search was done on PubMed, Cochrane Library, Embase, EBSCOhost, Web of Knowledge, and Google Scholar reporting on appliance design, bonding, and laboratory setup, biomechanics, survey studies, case reports, and treatment outcomes.
| An Insight into History of Lingual Orthodontics|| |
Lingual orthodontics started in 1970's when Fujita in Japan and Kurtz in the USA used lingual brackets for the first time. It made a sensational debut as lingual brackets were invisible, and the number of initiated cases increased exponentially. A few years later, the number of lingual orthodontic cases decreased greatly. The reason was very clear; most doctors could not achieve satisfactory results with lingual orthodontics. Following this, initial development and expansion of lingual orthodontics in the 1990s, interest, particularly in the United States, decreased, probably due to the poor results of completed cases.
As time passed and problem-solving associated with lingual orthodontics was improved, lingual orthodontics expanded around the world, specifically in European and Asiatic countries. Major developments in lingual orthodontics, which occurred around the world can be seen in the following timeline [Figure 1].
| Trends from Past to Present|| |
To see the trends in the fixed lingual orthodontics from the past to present, an electronic search of the literature published from 1978 to 2016 was done. The electronic data search was conducted on PubMed, Cochrane library, Embase, EBSCOhost, Web of Knowledge, and Google Scholar. Overall, 364 articles published on lingual orthodontics in English or dual language were picked using MeSH methodology of following key words: "lingual orthodontics," "lingual fixed orthodontics," "lingual fixed appliance," and "lingual orthodontic appliance."
The articles were divided into following eight broad categories: Appliance design, bonding and laboratory setup, biomechanics, oral hygiene and adverse effects, review articles, survey studies, case reports, and treatment outcome.
Out of 364 articles searched, there were 10% articles on appliance design, 18.9% on bonding and laboratory setup, 16.4% on biomechanics, 10.9% on oral hygiene and adverse effects, 15.6% on review articles, 3.5% on survey studies, 18.9% on case reports, and only 3.2% on treatment outcome [Graphs 1 and 2].
The graphical representation shows that there was a change in trend in articles published in the last four decades. After introduction of lingual orthodontics in 1970's, orthodontists were using lingual bracket system of Fujita and Kurtz till the end of 1990's, and there were few publications on appliance design in 1980's and 1990's. The major research on appliance design was started in the last two decades with 81% of total publications on appliance design.
Indirect bonding and laboratory setup is a very important step in lingual orthodontics for accurate treatment results. There were only 10% publications on indirect bonding and laboratory setup in 1980's and this percentage remained constant in 1990's. Due to failure of treatment in initial years, there was a surge of publications in the last two decades accounting to 79% of publications on bonding and laboratory setup.
As the biomechanics of lingual orthodontics is entirely different from that of labial orthodontics, there is an increasing trend of publications on biomechanics. In 1980's the focus was mainly on understanding the biomechanics of lingual therapy, in 1990's, there were publications on comparison of biomechanics in lingual and labial orthodontics. In the recent years, the focus has shifted to the torque control of the anterior teeth in lingual orthodontic treatment. It was found that 50% articles on biomechanics were published in the last 6 years.
As the number of patients seeking lingual orthodontics is increasing, 69% articles on case reports were published in the last 6 years as compared to 13% in 1990's.
Since last decade, researchers have started to focus on oral hygiene issues and adverse effects associated with lingual orthodontics. 57.5% of total articles on this issue have published in the last 6 years.
There is still a lacuna of research on treatment outcome with only 3.2% of total articles published on this topic in the last four decades. Hence, there is a need to further research to analyze the treatment outcome of lingual orthodontics.
| Current Evidence and Implications|| |
To find the current evidence of lingual orthodontics, out of 364 articles on lingual orthodontics, 190 articles published in the last decade were chosen from the year 2007 to December 2016. There were four systematic reviews and meta-analysis and four randomized controlled trials (RCTs) on lingual orthodontics, which were published in recent years. The current research progress in lingual orthodontics is described as follows:
| Appliance Design|| |
Lingual bracket system has evolved from first-generation Ormco lingual brackets to computer-aided design/computer-aided manufacturing (CAD/CAM)-based completely customized lingual appliance. First-generation Ormco lingual brackets of 1970's were evolved to seventh generation in 1990's, the changes were made in the profile of the bracket, addition of hooks, incorporation of rhomboidal shape bite planes, and increased mesiodistal width of the premolar brackets for better rotational control.
Mushroom archwires have been in use since Fujita started lingual orthodontics which typically requires vertical step bends and insets between canine and first premolar and complicated wire bends. Scuzzo and Takemoto in 1995 introduced lingual straight wire technique and STb brackets and demonstrated that lingual straight wires can be used if the brackets are repositioned gingivally since the difference in thickness of the canines and premolars decreases with the bonding height.
Weichmann in 2002 revolutionized the concept of lingual orthodontics by introducing CAD/CAM-based customized lingual appliance and robotic wire bending. In 2009, 3M Unitek took over this customized appliance and introduced it as Incognito™ lingual appliance.
Fillion in 2010, also developed a customized straight-wire technique, using the Orapix digital system to fabricate lingual appliances from a virtual setup.
There are many customized lingual systems available today: WIN (DW Lingual Systems GmbH), HARMONY (American Orthodontics), and Indian customized lingual systems: Lingual Matrix and iLingual 3D.
Scuzzo et al. in 2011 introduced first self-ligating lingual brackets with square slot. According to their experiments, the square slot (0.018 inch × 0.018 inch) is superior to rectangular slot in rotational control with both round and square archwires.
Kairalla et al. in 2014 established four lingual arch sizes: S, M, L, and XL and shape of lingual arch forms was described similar to a parabola, slightly flattened on its anterior region. Park et al. in 2015 also provided a new classification of maxillary and mandibular lingual arch forms: Narrow, tapering and ovoid according to intercanine and intermolar widths and their best-fit curves on lingual surface of dentition.,
| Indirect Bonding and Laboratory Setup|| |
The morphological variations of lingual dental surfaces limit the direct bonding of brackets on lingual surface accurately and precisely. Hence, indirect bonding technique is pivotal for success in lingual orthodontics. There are different laboratory techniques which have been developed for indirect positioning and bonding of lingual brackets. Laboratory setup for indirect bonding of lingual appliance can be divided into two categories, one is manual setup which uses patient's dental models and includes various methods (BEST, CLASS, and HIRO, etc.), the second is completely customized digital lingual setup (Orapix, WIN, HARMONY, Incognito™ and Lingual Matrix, and iLingual III D,) individualized for each patient, made by using patients scanned model or three-dimensional (3D) image and brackets are designed and manufactured by CAD/CAM technology.
| Biomechanics|| |
The biggest challenge in lingual orthodontics is to control inclination of anterior teeth during retraction phase. In the last decade, there are many studies on torque control of anterior teeth while treating with lingual appliance.
Biomechanical design constituting palatal mini-screws and lever arms make the point of application of retraction force at the level of center of resistance of the upper anterior teeth were seen to provide good torque control of anterior teeth during en-masse retraction as shown in a study conducted by Kim et al. in 2011.
Kim et al. in 2011 also tested different lengths of the lever arm (from 0 to 20 mm) in their finite element analysis study for en-masse retraction of maxillary anterior teeth with lingual technique. The results of this study showed that when the length of lever arm was 20 mm in the anterior segment and a retraction hook which was placed at the level of root apex of maxillary molar with help of trans-palatal arch, it resulted in translation of upper incisors, buccal displacement of canines, no extrusion of upper anterior teeth, and slight distal displacement of molars.
Lossdörfer et al. in 2014 and Daratsianos et al. in 2016, in their in vitro studies, analyzed and compared torque control capacity of completely customized lingual appliance and other lingual brackets and archwire combinations. These studies have shown that because of the high precision of the bracket slot-archwire combination in completely customized lingual appliance, an effective torque control was achieved with this appliance.,
| Adverse Effects|| |
Recently, published systematic reviews and RCTs have evaluated various adverse effects (speech, pain, eating difficulties, WSLs, oral hygiene, and periodontal status) related to fixed lingual orthodontics and have compared these with that of fixed labial appliance.
Objective auditive analysis and subjective questionnaire-based analysis have shown that patients with fixed lingual brackets have higher degrees of speech impairment. Speech difficulties were statistically more common with lingual than with buccal systems.
Patients with lingual appliances were more likely to report a perception of articulation change and avoidance of some types of conversation even after 3 months compared with patients with labial appliances. The patho-mechanism of speech impairment during lingual appliance therapy results from the contact area of the tongue being shifted further palatally as a result of the presence of lingual brackets.,,,
There are no significant differences in pain experienced during treatment between those treated with labial or lingual appliances. The only difference of pain experience in both techniques is that the patients with lingual appliance experienced more pain in tongue, whereas those treated with labial appliance experienced more pain in lip and cheek. Patients treated with lingual appliance reported experiencing pain earlier than those treated with labial appliance.
Ata-Ali et al. in 2016, in their systematic review, concluded that eating difficulties were not found to be statistically more common with lingual than with buccal appliances.
White spot lesions
It is advantageous that lingual fixed appliances are associated with reduced incidence of WSLs as compared to labial fixed appliance as reported by various studies including RCT and systematic reviews. An RCT conducted by van der Veen et al. in 2010, reported that the number of new WSLs developing or progressing on bracketed buccal surfaces was 4.8 times higher than the number of new WSL developing or progressing on fixed lingual surfaces. Wiechmann et al. in 2015, in their study on completely customized fixed lingual appliance also found distinctly reduced WSL.,,,,,,,
| Oral Hygiene and Periodontal Status|| |
Ata-Ali et al. in their meta-analysis, found a greater compromise in oral hygiene levels with lingual appliance. After analyzing, the clinical (bleeding on probing, plaque index, and probe depth) and microbiological findings (detection of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis in crevicular fluid) concluded that lingual orthodontics significantly worsen these parameters.
Long et al. in their systemic review also revealed that the prevalence of oral hygiene problems was similar within the first 3 months between lingual and labial fixed appliance.
One split-mouth study tested clinical periodontal and microbial indices before and 4 weeks after bonding of Incognito™ lingual appliances. Plaque index and bleeding on probing significantly increased in this period in the bonded sites while no significant difference was detected for pocket depth and periodonto-pathogenic bacteria.
| Clinical Outcome|| |
Alexander Harry Pauls in 2010 conducted a retrospective study on 25 patients treated in the practice of Dr. Dirk Wiechmann in Bad Essen, Germany, with customized Incognito® bracket system to demonstrate the possibility of achieving the therapeutic setup's goal in actual treatment. The therapeutic setup casts and final treatment casts were digitalized using a 3D scanner, and the scans were subsequently superimposed. The deviations in rotation and translation of each tooth in the three spatial dimensions were calculated.
The front teeth showed deviations in rotations of <4.6° and in translations under 0.5 mm. The final results following lingual orthodontic treatment using individualized brackets correlate satisfactorily with the therapeutic setups.
Fillion in 2010 outlined clinical advantages of the completely customized lingual bracket and archwire system, known as Orapix digital system which was developed in 2006 in South Korea. In this bracket system, brackets are positioned very close to the lingual surface of incisors, thus providing enhanced 3D control. High precision and completely customized brackets and archwires are claimed to provide ideal clinical positions of teeth as defined on the digital virtual setup.
Grauer and Proffit in 2011 evaluated accuracy in tooth positioning with fully customized appliance (Incognito™). Dental casts of 94 consecutive patients were scanned for this study. The results of this study shown that fully customized appliance (Incognito™) was accurate in achieving the goals of the planned treatment in the initial virtual digital setup except for the full amount of the planned arch expansion and the inclination of the second molar.
Mistakidis et al. in 2015 conducted the first systematic review on clinical outcome of lingual orthodontics to assess the available evidence on the effectiveness of lingual orthodontic treatment and other related clinical parameters (anterior teeth position, lower intercanine width, lower incisor proclination in lingual technique + Herbst appliance, deviations in peer assessment rating scores, anchorage loss, lower incisors crowding, WSLs, accidental brackets debonding, and treatment duration).
This systematic review showed encouraging results on the clinical outcome of lingual orthodontic treatment, especially in regard to the achievement of individualized treatment goals and the reduction of decalcifications on the bonded surfaces of the teeth.
| Case Reports|| |
With the advent of contemporary, completely customized lingual fixed orthodontic appliances and use of mini-screw implants, today any orthodontic case that can be treated with labial fixed appliance, can also be treated with lingual orthodontic appliance to a satisfactory level. There are several case reports from simple malocclusion to complex cases which have been treated with lingual fixed appliance.
There are several case reports with successful treatment using Herbst appliance in combination with lingual orthodontics by Wiechmann et al.,,, Bock et al.,, and Vu et al.
Kim et al. have reported a case with orthognathic correction of skeletal Class III malocclusion with customized lingual appliance. Jung et al. have reported a case of skeletal Class II malocclusion, severe anterior open bite, vertical maxillary asymmetry, and multiple missing teeth treated with customized lingual fixed appliances (Incognito™) along with double jaw surgery, and dental implants.
| Conclusion|| |
The current evidence on lingual orthodontics shows that any case that can be treated with labial orthodontic appliance can also be treated effectively with lingual orthodontic appliance. As the number of adult patients seeking orthodontic treatment is increasing, the demand for esthetic orthodontic appliance is also increasing. Lingual orthodontics is the only orthodontic appliance which has an advantage of complete invisibility and 3D control of orthodontic tooth movement. This review article has come to the following conclusions:
- The limitations of manual setups such as tedious laboratory procedures, inaccuracy in bracket positioning, frequent debonding of brackets, problem in rebonding of brackets, difficult and time-consuming manipulation of the appliance, inability to express and control the torque in anterior segment effectively and poor standard of treatment outcome, now can be easily addressed with the advent of completely customized lingual appliance
- The only issue with the completely customized lingual appliance today, is the cost of the appliance which can be overcome with the availability of advanced technology like "metal" 3D printers which directly can make the metal brackets without making the wax patterns as in the current method
- Biomechanical principles of lingual orthodontics have been completely understood and established today. The issue of torque control of anterior teeth can be addressed with the use of palatal mini-screws and lever arms which make the point of application of retraction force at the level of center of resistance of upper anterior teeth during en-masse retraction
- Patients with lingual appliances are more likely to report a perception of articulation change and avoidance of some types of conversation. The patient usually complaints of speech problems related to the lingual appliance that may persist until 1 month after onset of the lingual treatment or even after 3 months in some patients. There is no significant difference in pain experienced during treatment between those treated with labial or lingual appliances. Ata-Ali et al., in their meta-analysis, found a greater compromise in oral hygiene levels with lingual appliance
- It is advantageous that lingual fixed appliances are associated with reduced incidence of WSLs as compared to labial fixed appliance as reported by various studies including RCT and systematic reviews
- A systematic review has shown encouraging results of the clinical outcome associated with the lingual orthodontic treatment, especially in regard to the achievement of individualized treatment goals with the completely customized lingual appliance.
There is still a lacuna of research on treatment outcome with only 3.2% of total articles have published on this topic in the last four decades. Hence, there is a need to further research to analyze the treatment outcome of lingual orthodontics.
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Conflicts of interest
There are no conflicts of interest.
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