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Frictional resistance exerted by different lingual and labial brackets: an in vitro study.

Lombardo L, Wierusz W, Toscano D, Lapenta R, Kaplan A, Siciliani G - Prog Orthod (2013)

Bottom Line: The effect of various factors, namely bracket/base width, slot size, inter-bracket distance, and first- (ΘcI) and second-order (ΘcII) critical contact angles were evaluated and compared.The maximum force necessary to displace NiTi wires of two different diameters (0.012, 0.014) was measured, using both elastic and metal ligatures with conventional brackets.The frictional force necessary to displace the wires increased as the diameter of the wire increased in all tested brackets (p<0.01).

View Article: PubMed Central - PubMed

Affiliation: Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy. lulombardo@tiscali.it.

ABSTRACT

Background: Although much has been written on the implications of friction generated between orthodontic archwires and labial brackets, information on lingual brackets is still limited. Hence, we set out to investigate the frictional resistance exerted by different lingual and labial brackets, including both conventional and self-ligating designs. The effect of various factors, namely bracket/base width, slot size, inter-bracket distance, and first- (ΘcI) and second-order (ΘcII) critical contact angles were evaluated and compared.

Methods: A plaster model of a pretreatment oral cavity was replicated to provide 18 (9 upper and 9 lower) identical versions. The anterior segments of each were taken, and the canine and lateral and central incisors were mounted with either lingual (7th Generation, STb, New STb, In-Ovation L, ORJ) or labial (Mini-Mono, Mini Diamond, G&H Ceramic) brackets. Mechanical friction tests were performed on each type of bracket using a universal testing machine. The maximum force necessary to displace NiTi wires of two different diameters (0.012, 0.014) was measured, using both elastic and metal ligatures with conventional brackets.

Results: The frictional force necessary to displace the wires increased as the diameter of the wire increased in all tested brackets (p<0.01). Friction was significantly higher (p<0.001) with elastic ligatures, as compared with metal ones, in all conventional brackets. In the lower lingual group, significantly lower friction was generated at conventional lingual New STb brackets (p<0.01) and ORJ lingual brackets (p<0.05) than at self-ligating In-Ovation L lingual brackets. A significant statistical correlation between (ΘcI) and friction was detected in the lower labial bracket group.

Conclusions: Friction resistance is influenced not only by the bracket type, type of ligation, and wire diameter but also by geometric differences in the brackets themselves.

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Segmented plaster model with bracket positioned at halfway point of clinical crown.
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Fig1: Segmented plaster model with bracket positioned at halfway point of clinical crown.

Mentions: Eighteen plaster models (9 upper and 9 lower) were replicated from impressions of an untreated patient's oral cavity. The models featured a full set of fully erupted but misaligned permanent anterior teeth of normal shape and size, with no interproximal restoration, fractures, caries or age-related wear. No fractures or bubbles were present on the models, and crowding (Little's index) was no greater than 2 to 3 mm in order to limit potential notching between the archwire and bracket. Models of both the upper and lower arches were divided into segments featuring three teeth per sample: central incisor, lateral incisor, and canine (Figure 1). No distinction was made between the left and right segments. A total of eight commonly used orthodontic bracket types were tested, all with a 0.018 slot height, five lingual brackets namely In-Ovation L*, (DENTSPLY GAC International, Islandia, NY, USA), 7th Generation STb (Sybron Dental Specialties Ormco, Orange, CA, USA), New STb (Sybron Dental Specialties Ormco), ORJ lingual brackets (Hangzhou ORJ Medical Instrument & Materials, Hangzhou City, China), and STb (Sybron Dental Specialties Ormco) and three labial brackets namely Mini-Mono (Forestadent, St. Louis, MO, USA), Ormco Mini Diamond (Sybron Dental Specialties Ormco), and G&H Ceramic (G&H Wire Company, Greenwood, IN, USA). The lingual group included one example of a self-ligating bracket, indicated with an asterisk.Figure 1


Frictional resistance exerted by different lingual and labial brackets: an in vitro study.

Lombardo L, Wierusz W, Toscano D, Lapenta R, Kaplan A, Siciliani G - Prog Orthod (2013)

Segmented plaster model with bracket positioned at halfway point of clinical crown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384939&req=5

Fig1: Segmented plaster model with bracket positioned at halfway point of clinical crown.
Mentions: Eighteen plaster models (9 upper and 9 lower) were replicated from impressions of an untreated patient's oral cavity. The models featured a full set of fully erupted but misaligned permanent anterior teeth of normal shape and size, with no interproximal restoration, fractures, caries or age-related wear. No fractures or bubbles were present on the models, and crowding (Little's index) was no greater than 2 to 3 mm in order to limit potential notching between the archwire and bracket. Models of both the upper and lower arches were divided into segments featuring three teeth per sample: central incisor, lateral incisor, and canine (Figure 1). No distinction was made between the left and right segments. A total of eight commonly used orthodontic bracket types were tested, all with a 0.018 slot height, five lingual brackets namely In-Ovation L*, (DENTSPLY GAC International, Islandia, NY, USA), 7th Generation STb (Sybron Dental Specialties Ormco, Orange, CA, USA), New STb (Sybron Dental Specialties Ormco), ORJ lingual brackets (Hangzhou ORJ Medical Instrument & Materials, Hangzhou City, China), and STb (Sybron Dental Specialties Ormco) and three labial brackets namely Mini-Mono (Forestadent, St. Louis, MO, USA), Ormco Mini Diamond (Sybron Dental Specialties Ormco), and G&H Ceramic (G&H Wire Company, Greenwood, IN, USA). The lingual group included one example of a self-ligating bracket, indicated with an asterisk.Figure 1

Bottom Line: The effect of various factors, namely bracket/base width, slot size, inter-bracket distance, and first- (ΘcI) and second-order (ΘcII) critical contact angles were evaluated and compared.The maximum force necessary to displace NiTi wires of two different diameters (0.012, 0.014) was measured, using both elastic and metal ligatures with conventional brackets.The frictional force necessary to displace the wires increased as the diameter of the wire increased in all tested brackets (p<0.01).

View Article: PubMed Central - PubMed

Affiliation: Postgraduate School of Orthodontics, University of Ferrara, Ferrara, Italy. lulombardo@tiscali.it.

ABSTRACT

Background: Although much has been written on the implications of friction generated between orthodontic archwires and labial brackets, information on lingual brackets is still limited. Hence, we set out to investigate the frictional resistance exerted by different lingual and labial brackets, including both conventional and self-ligating designs. The effect of various factors, namely bracket/base width, slot size, inter-bracket distance, and first- (ΘcI) and second-order (ΘcII) critical contact angles were evaluated and compared.

Methods: A plaster model of a pretreatment oral cavity was replicated to provide 18 (9 upper and 9 lower) identical versions. The anterior segments of each were taken, and the canine and lateral and central incisors were mounted with either lingual (7th Generation, STb, New STb, In-Ovation L, ORJ) or labial (Mini-Mono, Mini Diamond, G&H Ceramic) brackets. Mechanical friction tests were performed on each type of bracket using a universal testing machine. The maximum force necessary to displace NiTi wires of two different diameters (0.012, 0.014) was measured, using both elastic and metal ligatures with conventional brackets.

Results: The frictional force necessary to displace the wires increased as the diameter of the wire increased in all tested brackets (p<0.01). Friction was significantly higher (p<0.001) with elastic ligatures, as compared with metal ones, in all conventional brackets. In the lower lingual group, significantly lower friction was generated at conventional lingual New STb brackets (p<0.01) and ORJ lingual brackets (p<0.05) than at self-ligating In-Ovation L lingual brackets. A significant statistical correlation between (ΘcI) and friction was detected in the lower labial bracket group.

Conclusions: Friction resistance is influenced not only by the bracket type, type of ligation, and wire diameter but also by geometric differences in the brackets themselves.

Show MeSH