Shear bond strength evaluation of metallic brackets bonded to a CAD/CAM PMMA material compared to traditional prosthetic temporary materials: an in vitro study

Abstract

Introduction: Orthodontic treatment for adults is currently increasing, and therefore the need to bond brackets to restorations and temporary crowns. The use of CAD/CAM PMMA provisional restorations for orthodontic purposes have not yet been described, and there is currently insufficient information regarding the strength of bracket adhesion. Objective: This study aimed at evaluating the effects of thermocycling (TC) and surface treatment on shear bond strength (SBS) of brackets to different provisional materials. Methods: Forty specimens were made from each material [PMMA (Telio Lab), bis-acryl (Telio CS C&B), and PMMA CAD/CAM (Telio CAD)], sandpapered, and divided according to surface treatment (pumiced or sandblasted) and TC (half of the samples = 1,000 cycles, 5°C/55°C water baths) (n = 10/group). Stainless-steel brackets were bonded to the specimens (using Transbond XT), and SBS testing was performed. Data were analyzed by three-way ANOVA and LSD post-hoc tests (α = 0.05). Failure types were classified with adhesive remnant index (ARI) scores. Results: SBS values ranged from 1.5 to 14.9 MPa. Sandblasted bis-acryl and sandblasted auto-curing PMMA groups presented similar values (p> 0.05), higher than the CAD/CAM material (p< 0.05), with or without TC. When thermocycled, pumiced bis-acryl showed higher SBS than pumiced acrylic (p= 0.005) and CAD/CAM materials (p= 0.000), with statistical difference (p= 0.009). TC showed negative effect (p< 0.05) for sandblasted bis-acryl and pumiced acrylic groups. ARI predominant score was mostly zero (0) for CAD/CAM, 1 and 2 for bis-acryl, and 1 for acrylic groups. Conclusion: In general, bis-acryl material showed the highest SBS values, followed by acrylic and CAD/CAM materials, which showed SBS values lower than an optimum strength for bonding brackets.

Effect of Different Primers on the Shear Bond Strength of Orthodontic Brackets Bonded to Reinforced Polyetheretherketone (PEEK) Substrate

“…In orthodontic practice, obtaining optimal SBS rather than the maximum possible SBS is preferable [ 32 ]. Brackets bonded to fixed prosthodontic surfaces should be compatible to resist the oral biomechanics, masticatory forces, and functional activities of the patient, but also adequate enough to facilitate debonding upon treatment completion without any deleterious effect on the bonded surface of the restoration [ 33 ].…”

Influence of the ringer's solution on wear of vacuum mixed poly(methyl methacrylate) bone cement in reciprocating sliding contact with AISI 316l stainless steel

“…Poly(methyl methacrylate) (PMMA) [(C5O2H8)n] based bone cements belong to a group of synthetic nondegradable, biocompatible polymeric hard biomaterials. Acrylic bone cements have versatile applications such as: cemented hip implants [1], spinal treatments [2], custom made bone implants [3], dental applications like orthodontic brackets [4] and occlusal splints [5]. PMMA is an isotropic, elasto-visco-plastic solid and amorphous/glassy polymer material.…”

“…Nguyen et al [10] considered a cyclic fatigue crack growth as the major governing factor of the bone cement failure, considering approximately five million steps per year for one person, meaning that the joint prosthesis should endure around 10 8 cyclic motions during its lifetime. Also, in dentistry, steel brackets are in close contact with PMMA [4]. On the other hand, articulating surfaces of loose joint replacements generate wear debris during the contact.…”

“…Questions related to sites of crack initiation, development mechanisms and the final failure point in the case of PMMA bone cements still remain, even though there are many studies focused on some specific aspects, like the surface finish in dental applications [4], or mechanisms that govern crack branching [15]. Some reports indicate that the start of separation of the cement from the metal stem is initiated by large fractures within the cement layer [10].…”

A method of fabricating computer aided design‐computer aided manufacturing implant‐supported provisional restorations with clear aligner attachments: A technical report

“…During orthodontic treatment, brackets and other attachments are bonded on provisional restorations and forces are applied conventionally. However, several studies have revealed that PMMA achieves low bond strength with resin cement or composite, [1][2][3][4][5] indicating that attachments have a higher risk of debonding.…”