Accuracy of lingual straight-wire orthodontic treatment with passive self-ligating brackets and square slot: a retrospective study.

OBJECTIVES: To investigate the accuracy of torque, tip and rotation and linear intra-arch movements yielded by passive self-ligating lingual straight-wire appliances with brackets featuring square slots. MATERIALS AND METHODS: Twenty-five adult Caucasian patients (16 females and 9 males; mean age 26.5 ± 4.3 years) with Class I or mild Class II head-to-head malocclusion were orthodontically treated via passive lingual self-ligating straight-wire appliances (ALIAS, Ormco, Orange, CA) with no extraction. Records were retrospectively analysed, and digital models of pre-treatment (T0), planned (T1) and achieved (T2) phase were acquired for both arches in each patient via an intraoral scanner (Medit I500 (iScan Medit, Seoul, Korea). VAM software (Vectra, Canfield Scientific, Fairfield, NJ, USA) was used to measure both angular values (torque, tip and rotation) and linear intra-arch widths (between canines, first and second premolars and first and second molars). Measurements were obtained for all the movements investigated for each tooth group (incisors, canines, premolars and molars), by arch (maxillary and mandibular) and for both arches at T0, T1 and T2. The accuracy of angular values was compared using Student's t-test against a hypothetical 100%, and among the various tooth groups by post-hoc tests. Transverse linear measurements were investigated by means of the non-parametric Friedman test. The significance threshold was set at 0.05. RESULTS: The mean accuracy of angular values was 77.25 ± 7.71% for torque, 78.41 ± 6.17% for tip and 77.99 ± 6.58% for rotation. In all cases, however, there was a significant difference between planned and achieved movements, and accuracy was significantly lower than the hypothetical 100% for all tooth groups, individual arches and dentition (p < 0.001). For intra-arch diameters, the greatest accuracy values were found for the anterior sectors (83.54 ± 5.19% for the maxillary inter-canine distance) and the lowest for the posterior sectors (67.28% for the maxillary inter-second molar distance). CONCLUSION: Straight-wire lingual treatment with passive self-ligating appliances featuring with square slot displayed excellent clinical accuracy, albeit with statistical accuracy decreasing antero-posteriorly.

Short- and Medium-Term Effects of Low-Level Laser Therapy on Periodontal Status in Lingual Orthodontic Patients.

OBJECTIVE: The purpose of this study was to evaluate the short- and medium-term effects of low-level laser therapy (LLLT) applied in repeated doses in adults with a healthy periodontium treated by lingual orthodontic appliances. BACKGROUND DATA: Plaque accumulation, in combination with difficulty in removing it in lingual orthodontic patients, can cause gingival inflammation. METHODS: Twelve orthodontic patients scheduled for fixed lingual orthodontic treatment were selected. Clinical measurements [visible plaque index (VPI), bleeding on probing (BOP), and probing depth (PD), and collection of gingival crevicular fluid (GCF)], which was used to measure the levels of interleukin-1beta (IL-1ß) and tumor necrosis factor alpha (TNF-α), was performed before bonding the lingual device, and at the short-term (1, 2, 3 months) and medium-term (12 months) follow-up appointments. For each patient, quadrant 1 or 2 was randomly chosen for irradiation by a diode laser (λ = 670 nm, 190 mW, 6.05 W/cm(2), 60 sec/ tooth) (Laser Group) and the contralateral quadrant was used as the Control Group. RESULTS: In both studied groups, a slight worsening of the periodontal condition was observed, which was evident at the 3rd month follow-up and which was mainly at the lingual side in the Control Group. The levels of IL-1ß in the GCF were significantly increased in the Control Group compared with the Laser Group at the 2nd and 3rd months after bonding. At the 12th month follow-up, an improvement of the inflammation was observed in both groups in the study. CONCLUSIONS: LLLT showed short-term effects by preventing a substantial increase in IL-1ß levels. At medium-term follow-up, LLLT diminished VPI, BOP, and PD scores.

Determining shapes and dimensions of dental arches for the use of straight-wire arches in lingual technique

INTRODUCTION: This study aims to determine the shape and dimension of dental arches from a lingual perspective, and determine shape and size of a straight archwire used for lingual Orthodontics. METHODS: The study sample comprised 70 Caucasian Brazilian individuals with normal occlusion and at least four of Andrew's six keys. Maxillary and mandibular dental casts were digitized (3D) and the images were analyzed by Delcam Power SHAPET 2010 software. Landmarks on the lingual surface of teeth were selected and 14 measurements were calculated to determine the shape and size of dental arches. RESULTS: Shapiro-Wilk test determined small arch shape by means of 25th percentile (P25%) - an average percentile for the medium arch; and a large one determined by means of 75th percentile (P75%). T-test revealed differences between males and females in the size of 12 dental arches. CONCLUSION: The straight-wire arch shape used in the lingual straight wire technique is a parabolic-shaped arch, slightly flattened on its anterior portion. Due to similarity among dental arch sizes shown by males and females, a more simplified diagram chart was designed. .

INTRODUÇÃO: esse estudo objetiva encontrar a forma e dimensão de arcadas dentária para definir a forma de um arco contínuo que possa ser utilizado na técnica lingual. MÉTODOS: a amostra foi composta por indivíduos brasileiros, leucodermas, com oclusão normal natural, que apresentaram, no mínimo, quatro das seis chaves de oclusão de Andrews. Os modelos das arcadas dentárias superior e inferior foram digitalizados (3D) e as imagens exportadas para o software Delcam Power SHAPETM 2010. Foram selecionados pontos nas superfícies linguais dos dentes e traçadas 14 medidas para determinar a forma e a dimensão da arcada dentária. RESULTADOS: o teste de Shapiro-Wilk possibilitou definir uma forma de arcada pequena utilizando o percentil 25% (P25%), uma arcada média (P50%) e uma forma de arcada grande, pelo percentil 75% (P75%). O teste t de Student comparou se houve uma diferença entre os sexos, e foram encontrados 12 tamanhos de arcadas dentárias. CONCLUSÕES: a partir dos resultados obtidos foi possível definir uma forma de arco contínuo para ser utilizado na técnica lingual Straight Wire (LSW): parábola levemente achatada na região anterior. Devido a similaridade entre alguns tamanhos de arcadas dentárias, encontrados pelo dimorfismo sexual, pôde ser elaborado um diagrama de arcadas de maneira mais simplificada. .

3D FEM comparison of lingual and labial orthodontics in en masse retraction.

BACKGROUND: The aim of this study was to compare displacements and stress after en masse retraction of mandibular dentition with lingual and labial orthodontics using three-dimensional (3D) finite element models (FEM). METHODS: A 3D FEM of each lower tooth was constructed and located as appropriate to Roth's prescription. The 0.018-in. GAC Roth Ovation labial and Ormco 7th Generation lingual brackets were virtually bonded to the lower teeth and threaded with 0.018 × 0.025- and 0.016 × 0.022-in. SS labial (Tru-Arch form, small size) and lingual (mushroom) archwires. En masse retraction was simulated by applying 300 g of distal force from the canine to the second premolar on the 0.016 × 0.022-in. SS labial and lingual archwires. The type of finite element used in the analysis was an eight-noded brick element. The Algor program (Algor Inc., Pittsburgh, PA, USA) was used to calculate the strains and displacements at each nodal point. RESULTS: Lingual tipping and extrusion of the anterior dentition occurred with both archwires. At the premolars and first molars, intrusion, lingual movements, and lingual tipping were seen with the labial archwire, while intrusion was accompanied by labial movements, mesial tipping, and buccal rotation with lingual mechanics. CONCLUSIONS: Lingual vs. labial bracket placement influences the pattern of tooth movement, but the stress that occurs around the teeth can be accurately mapped using a 3D FEM model.

Determining shapes and dimensions of dental arches for the use of straight-wire arches in lingual technique.

INTRODUCTION: This study aims to determine the shape and dimension of dental arches from a lingual perspective, and determine shape and size of a straight archwire used for lingual Orthodontics. METHODS: The study sample comprised 70 Caucasian Brazilian individuals with normal occlusion and at least four of Andrew's six keys. Maxillary and mandibular dental casts were digitized (3D) and the images were analyzed by Delcam Power SHAPET 2010 software. Landmarks on the lingual surface of teeth were selected and 14 measurements were calculated to determine the shape and size of dental arches. RESULTS: Shapiro-Wilk test determined small arch shape by means of 25th percentile (P25%)--an average percentile for the medium arch; and a large one determined by means of 75th percentile (P75%). T-test revealed differences between males and females in the size of 12 dental arches. CONCLUSION: The straight-wire arch shape used in the lingual straight wire technique is a parabolic-shaped arch, slightly flattened on its anterior portion. Due to similarity among dental arch sizes shown by males and females, a more simplified diagram chart was designed.

Ortodontia Lingual no preparo do tratamento ortodôntico-cirúrgico / Lingual Orthodontics in the preparation of orthodontic-surgical treatment

No final dos anos 70 surgiu a técnica ortodôntica lingual com a promessa de um tratamento ortodôntico estético e, apesar da dificuldade inicial, a técnica hoje apresenta uma grande evolução. Atualmente, existe uma grande procura por tratamentos ortodônticos, principalmente por pacientes adultos e adultos jovens. Esses pacientes procuram por uma alternativa estética de tratamento, o que pode perfeitamente ser conseguido com a técnica lingual. Porém, dentre muitos casos, observa-se que com um correto diagnóstico, faz-se necessária a complementação e/ou correção por meio de cirurgia ortognática. Esta, por sua vez, também está mais sedimentada e simplificada e vem sendo bem aceita pelos pacientes como técnica complementar no tratamento da má oclusão, pois além de realizar modificações na face, proporciona ao paciente um grande benefício estético. Assim, este caso visa demonstrar que partir de um correto diagnóstico é possível realizar a correção da má oclusão e da discrepância óssea com um tratamento ortodôntico estético, no caso com a técnica lingual, associada com cirurgia ortognática.

In the late 70’s lingual orthodontics technique with emerged as an orthodontic treatment with the benefit of preserving aesthetic during treatment. Despite initial difficulties, the technique had a great evolution until present days. Currently, there is a great demand for orthodontic treatment, especially as adult and young adults. These patients search for an aesthetic treatment what is perfectly possible to achieve with the lingual technique. However, among many cases, it was observed that after proper diagnosis a complementation and/or correction through orthognathic surgery is required. This surgical procedure has also became more simple and is better accepted by patients as a complementary technique in the treatment of malocclusion, since beside modifying the face, it offers great aesthetic benefits to the patients. Thus, this clinical case report aims to demonstrate that with a proper diagnosis it is possible to perform the correction of malocclusion and bone discrepancy using lingual orthodontics technique associated with orthognathic surgery.

Changes in the oral environment after placement of lingual and labial orthodontic appliances.

BACKGROUND: This study compared the oral hygiene and caries risk of patients treated with labial and lingual orthodontic appliances throughout a prospective evaluation of the status of the oral environment before and after bracket placement. METHODS: A total of 20 orthodontic patients aged 19 to 23 years were included in the study and were divided into two groups: 10 patients wore Roth labial appliance (American Orthodontics, Sheboygan, WI, USA) and 10 patients wore STb lingual appliance (Ormco Corporation, Glendora, CA, USA). Plaque index (PI), gingival bleeding index (GBI), salivary flow rate, saliva buffer capacity, salivary pH, and Streptococcus mutans and Lactobacillus counts in saliva were determined at three time points: before orthodontic appliance placement (T0), 4 weeks after bonding (T1), and 8 weeks after bonding (T2). After appliance placement, all patients were periodically educated to the oral hygiene procedures. Wilcoxon rank and Mann-Whitney U tests were used to determine intragroup and intergroup differences as regards qualitative data. To compare quantitative data between the groups, chi-square and Fisher's exact tests were undertaken, while intragroup differences were tested with McNemar test. The level of statistical significance was set at p<0.05. RESULTS: Statistical analysis of the data obtained revealed a statistically significant difference between the data of T0 and T1 and the data of T0 and T2 of the PI scores and between T0 and T2 of the GBI scores in the group treated with the lingual appliance. The GBI value increased significantly between T0 and T1 but decreased significantly between T1 and T2 (p<0.01) in the group treated with labial appliance. S. mutans counts increased significantly between T0 and T2 in the saliva samples of patients treated with lingual appliance. No statistically significant differences were found between S. mutans and Lactobacillus counts at the three terms of saliva collection in patients treated with labial appliance. No statistically significant differences were found between the two groups at the three time points as regards the salivary flow rate and saliva buffer capacity. CONCLUSIONS: Lingual and labial orthodontic appliances showed a different potential in modifying the investigated clinical parameters: patients wearing STb lingual orthodontic appliance had more plaque retention 4 and 8 weeks after bonding, while there were more gingival inflammation and more S. mutans counts 8 weeks after bonding. No differences were found between the two groups as regards the Lactobacillus counts, the salivary flow rate, and saliva buffer capacity.

Three-dimensional finite-element analysis of a central lower incisor under labial and lingual loads.

INTRODUCTION: The aim was to evaluate the differences between labial and lingual application of an orthodontic force. This was achieved using a three-dimensional CAD design software model of a real lower incisor surrounded by a prismatic representation of the mandibular bone. This model was subjected to various loading conditions, with finite-element analysis. MATERIALS AND METHODS: Cone-beam computed tomography scanning was used to create a three-dimensional geometric model of a lower incisor, together with its simulated periodontal ligament. This model was then meshed and analysed with commercial finite-element code. Various single and combined forces and moments were applied to each side of the simulated lower incisor at the centre of the clinical crown. To evaluate the effects of the various forces considered, the instantaneous displacement and stress generated in the bone and the periodontal ligament were measured, as a comparison of the labial and lingual loading sites. RESULTS: Dental movement was only influenced by the side of the force application when an intrusive component was present. The simulations showed larger displacement when a vertical force was present at the lingual surface. In general, this movement was of the tipping type when the combined forces were applied, while there was greater intrusion upon application of combined forces and an anticlockwise moment to the labial surface. CONCLUSIONS: Application of an intrusive lingual force to a lower incisor appears to generate bodily movement, while the same intrusive labial force appears to lead to labial tipping. Subject to further study, this should be taken into consideration when devising treatment plans for fixed appliances.

A comparative study of lingual bracket bond strength.

AIM: To compare the adhesive potential, the mechanics implicated in adhesive failure, and the effect on the enamel of four brands of lingual brackets. METHODS: One hundred sixty premolars and four types of commercially available lingual brackets (STB, ORG, Magic, and Stealth) were selected. Forty brackets per manufacturer were used, half bonded directly and half indirectly. Each of these bonding groups was further subdivided: 10 brackets were bonded without treatment, while the other 10 were sandblasted. Thus, a total of four groups were created for each type of bracket: (a) sandblasted and directly bonded, (b) sandblasted and indirectly bonded, (c) not sandblasted and directly bonded, and (d) not sandblasted and indirectly bonded. Immediately after bonding, each bracket was tested for adhesion strength, and each appliance was then examined via electron microscopy to calculate the ARI. RESULTS: Statistical analysis showed a significant difference among the four bracket types; a general improvement in lingual appliance mechanical features provoked by sandblasting, albeit with some exceptions; and no significant effect of bonding method on the degree of bond strength. The ARI revealed that the most common area of adhesion crisis was at the adhesive-bracket interface. CONCLUSION: Overall, STB brackets performed better, and sandblasting proved to be an efficient way of improving the mechanical features of lingual brackets. Bonding technique, on the other hand, did not seem to exert a great influence on bonding success, and the bracket-adhesive interface was identified as the area most prone to failure.

Wire load-deflection characteristics relative to different types of brackets.

OBJECTIVE: To test the hypothesis that the dimension of the bracket, both in labial and in lingual orthodontics, is a relevant parameter to determine the forces acting on the teeth, and that some wires commonly used in labial orthodontics (0.016"-diameter SS, TMA and Nitinol) are not suitable for the first phase of lingual treatment. MATERIALS AND METHODS: An ideal dental cast was bonded with eight different brackets (Damon 3MX, Ovation, Time 2, Innovation and Smart Clip Clarity on the vestibular face; STB, Adenta Time and Innovation-L on the lingual). After photographic documentation, the interbracket distance was calculated for each type of bracket, using ImageJ software. The mean elasticity modulus of the tested wires was obtained from the review of the available literature. The theoretical wire load on every tooth was calculated mathematically at three different levels of deflection (0.5mm; 1.0mm and 1.5mm), on both the labial and lingual sides, for all types of bracket. RESULTS: The lingual arch in the anterior segment is always shorter than the vestibular arch. The different brackets, having different dimensions, have an influence on the interbracket distance, and, consequently, on the wire load. At large deflections, superelastic NiTi expresses light and continuous forces, which are significantly lower than the other examined alloys. CONCLUSION: The initial hypothesis was supported. Because of the reduced interbracket distance, the adoption of superelastic wires is required in lingual mechanics and with smaller diameter compared to labial mechanotherapy, in particular during the first phases of treatment. The use of a bracket with reduced mesiodistal dimensions can contribute to reduce the load on the teeth.

A new concept of anatomic lingual arch form.

INTRODUCTION: The aim of this study was to describe a natural and anatomic lingual arch form obtained from subjects with normal occlusion that could be used, with other criteria, in the construction of personalized setups for the lingual straight-wire technique. METHODS: The study sample comprised 58 pairs of dental casts of the arches of 58 southern Europeans (37 women, 21 men) with ideal natural occlusions. After the reference points of the dental arches were identified and marked, the dental casts were scanned. The exact position of the models on the scanner was established by using an acetate sheet with a Cartesian reference system. For each image, 14 reference points (x, y) were measured and recorded. The measurements were processed with software to select the polynomial function that best described the shape of the dental arches. The ninth-degree polynomial function was selected to represent the lingual arch form of both arches. Distribution analysis of the x and y values of each tooth in each arch resulted in the creation of 3 groups (small, medium, and large) to verify the most appropriate measures of the central tendencies of our data. RESULTS: Statistical analysis showed no significant sex difference in the medians of the 6 parameters used to measure depth and width in both arches. A representation of the variability of the lingual curve of our sample was created to document at least 3 sizes of the representative curve of the central tendency for our data. No statistically significant differences in shape were found between men and women, considering the medians as a measure of the central tendencies. CONCLUSIONS: Three lingual curves (small, medium, and large) for the maxillary and mandibular arches, representing the mean values of our sample, were developed and can be used as guides for the setup in the lingual straight-wire technique.

Lingual straight wire method.

The mushroom arch-wire is mainly used in lingual orthodontic treatment but the complicated wire bending it requires affects both the treatment results and the time spent at the chair. The author proposes a new lingual straight wire method (LSW) in order to facilitate arch coordination and simplify the mechanics. The attention paid to the set-up model and bracket positioning and bonding plus the use of the new LSW method will also improve patient comfort.