Debonding forces of different pads in a lingual bracket system.

Valter O Arima,Adriana S Lucato,Milton Santamaria Jr,Heloísa C Valdrighi,Silvia A S Vedovello,Mario Vedovello Filho

doi:10.1590/2177-6709.22.4.034-040.oar

Valter O Arima, Adriana S Lucato + Show 4 more

Open Access

https://doi.org/10.1590/2177-6709.22.4.034-040.oar

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Abstract

ABSTRACTObjective: To evaluate the shear bond strength of lingual orthodontic brackets with resin or metal pads, the location of bond failure and the adhesive remnant index (ARI). Methods: A total of 40 extracted upper premolars were randomly divided into two groups of 20 each: bonding with brackets having (1) pads with extended resin directly on the lingual surface of teeth, and (2) pads with metal custom base on the lingual surface of teeth. The debonding force was measured with an Instron universal testing machine. A Student’s t-test was used to assess the difference between groups (α = 0.05). Results: The results showed a significant difference between the groups (p < 0.001). The shear bond strength of metal pads was significantly higher than resin pads. Conclusions: Within the limitations of this in vitro study, it was concluded that the bond strength of lingual brackets with metal pads was higher than that of brackets with composite resin pads, due to the metal part being a single unit and welded. The failure location in the region between the bracket and the resin pad affected a higher percentage of the resin pads than the metal pads.

Highlights

The lingual technique offers significant aesthetic advantages for patients submitted to orthodontic treatment, and demands continuous development of brackets[1,2] and related materials, aiming to obtain results similar to those from conventional labial orthodontic treatment.[3]For better adaptation to the lingual surface of teeth, compensations have been created at the bracket bases
Failures were observed between the pad and bracket for both groups, with this percentage being 70% for the resin pads, and 45% for the metal pads
There was 30% fracture of the tooth in the customized metal pads, due to the high resistance of force required for shearing (Fig 3)

Summary

Introduction

The lingual technique offers significant aesthetic advantages for patients submitted to orthodontic treatment, and demands continuous development of brackets[1,2] and related materials, aiming to obtain results similar to those from conventional labial orthodontic treatment.[3]For better adaptation to the lingual surface of teeth, compensations have been created at the bracket bases. There are several options available for lingual systems, and due to the wide variation in the morphology of tooth surface, making an individual customized base for each bracket has shown to be the most adequate option, with the purpose of avoiding bends in the arches during the course of treatment.[6] At present, there are systems available in which the lingual bracket is fabricated by means of computeraided design (CAD) and computer-aided manufacturing (CAM) This technology minimizes the bracket profile and reduces discomfort to the patient, because customized metal pads and brackets are case in a single unit.[7] In spite of the technology provided by 3D digitization in lingual appliances,[8,9] their cost is still high in comparison to the conventional lingual technique. It is worth pointing out that the literature is not conclusive with respect to the resistance of brackets with different bases or pads used in the lingual orthodontic technique.[6,10]

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