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Comparative analysis of slot dimension in lingual bracket systems.

Demling A, Dittmer MP, Schwestka-Polly R - Head Face Med (2009)

Bottom Line: Data were compared using one-way ANOVA.Differences between systems were statistically significant (p < 0.05).The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Orthodontics, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany. Demling.Anton@mh-hannover.de

ABSTRACT

Background: Orthodontic treatment with fixed appliances requires - among others - the correct clinical expression of torque, which depends on the precise fitting of archwire and slot. Especially in the lingual technique torque problems become clinically more evident than in labial appliances also with respect to the vertical alignment of teeth due to different distances from the center of resistance. The purpose of the present study was to compare the preciseness of slot dimensions of different lingual bracket systems.

Methods: Three lingual bracket systems were included in the study (7th Generation and STb, Ormco, Glendora, CA, USA; Incognito, TOP-Service/3 M Unitek, Monrovia, CA, USA). Non destructive analysis of vertical slot dimensions was performed using precision pin gauges (Azurea, Belprahon, Switzerland) that were tapered in increments of 0.002 mm (0.00008 inch). The sizes of 240 incisor and canine brackets were measured per system (total: 720). Data were compared using one-way ANOVA. A p-value < 0.05 was considered statistically significant.

Results: Average slot dimensions were 0.467 mm +/- 0.007 mm (0.0184 inch +/- 0.0003 inch) for the 7th Generation bracket system, 0.466 mm +/- 0.004 mm (0.0183 inch +/- 0.0001) inch for the STb bracket system and 0.459 mm +/- 0.004 mm (0.0181 inch +/- 0.0001) inch for the Incognito bracket system. Differences between systems were statistically significant (p < 0.05).

Conclusions: The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play. These aspects must be considered in lingual orthodontic treatment.

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Effects of torque loss. Comparison of torque loss (-15 degrees) in lingual and buccal technique with respect to vertical side effects (CR = Centre of Rotation).
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Figure 1: Effects of torque loss. Comparison of torque loss (-15 degrees) in lingual and buccal technique with respect to vertical side effects (CR = Centre of Rotation).

Mentions: Besides visibility of the appliance during orthodontic treatment, the labio-lingual inclination of maxillary and mandibular incisors and canines is considered by patients and orthodontists to be an important determinant in providing esthetic outcome after orthodontic treatment. Furthermore, the correct inclination of the anterior teeth is essential in providing good occlusion in anterior and posterior regions, and is basically dependent on the correct expression of torque. This torque expression can be achieved by using slot-filling archwires or twisting and inserting undersized archwires. Nevertheless, various factors affect the correct torque expression of a preadjusted appliance [12]. These factors include material properties such as hardness and modulus of elasticity of the archwire and bracket, variations of manufacturing processes including milling and casting of brackets, as well as clinical procedures like mode of ligation [13,14]. Furthermore, a patient's individual tooth morphology also influences the clinical outcome of torque [15,16]. In the literature, it was shown that oversized slots lead to a clinically relevant torque loss [17]. Due to the longer lever arm in lingual orthodontics, slot precision must be considered as a key factor that influences tooth position not only in the labio-lingual but also in the vertical dimension [18] (see Figure 1).


Comparative analysis of slot dimension in lingual bracket systems.

Demling A, Dittmer MP, Schwestka-Polly R - Head Face Med (2009)

Effects of torque loss. Comparison of torque loss (-15 degrees) in lingual and buccal technique with respect to vertical side effects (CR = Centre of Rotation).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2803453&req=5

Figure 1: Effects of torque loss. Comparison of torque loss (-15 degrees) in lingual and buccal technique with respect to vertical side effects (CR = Centre of Rotation).
Mentions: Besides visibility of the appliance during orthodontic treatment, the labio-lingual inclination of maxillary and mandibular incisors and canines is considered by patients and orthodontists to be an important determinant in providing esthetic outcome after orthodontic treatment. Furthermore, the correct inclination of the anterior teeth is essential in providing good occlusion in anterior and posterior regions, and is basically dependent on the correct expression of torque. This torque expression can be achieved by using slot-filling archwires or twisting and inserting undersized archwires. Nevertheless, various factors affect the correct torque expression of a preadjusted appliance [12]. These factors include material properties such as hardness and modulus of elasticity of the archwire and bracket, variations of manufacturing processes including milling and casting of brackets, as well as clinical procedures like mode of ligation [13,14]. Furthermore, a patient's individual tooth morphology also influences the clinical outcome of torque [15,16]. In the literature, it was shown that oversized slots lead to a clinically relevant torque loss [17]. Due to the longer lever arm in lingual orthodontics, slot precision must be considered as a key factor that influences tooth position not only in the labio-lingual but also in the vertical dimension [18] (see Figure 1).

Bottom Line: Data were compared using one-way ANOVA.Differences between systems were statistically significant (p < 0.05).The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Orthodontics, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany. Demling.Anton@mh-hannover.de

ABSTRACT

Background: Orthodontic treatment with fixed appliances requires - among others - the correct clinical expression of torque, which depends on the precise fitting of archwire and slot. Especially in the lingual technique torque problems become clinically more evident than in labial appliances also with respect to the vertical alignment of teeth due to different distances from the center of resistance. The purpose of the present study was to compare the preciseness of slot dimensions of different lingual bracket systems.

Methods: Three lingual bracket systems were included in the study (7th Generation and STb, Ormco, Glendora, CA, USA; Incognito, TOP-Service/3 M Unitek, Monrovia, CA, USA). Non destructive analysis of vertical slot dimensions was performed using precision pin gauges (Azurea, Belprahon, Switzerland) that were tapered in increments of 0.002 mm (0.00008 inch). The sizes of 240 incisor and canine brackets were measured per system (total: 720). Data were compared using one-way ANOVA. A p-value < 0.05 was considered statistically significant.

Results: Average slot dimensions were 0.467 mm +/- 0.007 mm (0.0184 inch +/- 0.0003 inch) for the 7th Generation bracket system, 0.466 mm +/- 0.004 mm (0.0183 inch +/- 0.0001) inch for the STb bracket system and 0.459 mm +/- 0.004 mm (0.0181 inch +/- 0.0001) inch for the Incognito bracket system. Differences between systems were statistically significant (p < 0.05).

Conclusions: The analyzed bracket systems for lingual treatment exhibited significant differences in slot dimension that will clinically result in torque play. These aspects must be considered in lingual orthodontic treatment.

Show MeSH