If you’re in the market for a new temporary material, you’re most likely narrowing your choices among bis-acryl composite resins. Contemporary bis-acryls have risen in popularity as studies and experience have shown that methyl-methacrylates (MMA) and ethylmethacrylates have less-than-ideal properties.
In this article, we’ll discuss how bis-acryl is a more appealing choice for both you and your patient according to the 5 senses. We’ll also discuss Access Crown temporary crown-and-bridge material from Centrix, a product designed for efficient and accurate fabrication of temporaries. Access Crown has unique qualities and certain advantages over other bis-acryl materials, as described by Christopher A. Hopper, DDS, based on his clinical experience.
Does your temporization material pass the smell test? Dr. Hooper says bis-acryl provisional materials are “significantly better” than traditional methyl-methacrylates and ethyl-methacrylates for “several good reasons.” His top-of-mind reason is the volatile vapor of methacrylates, which tend to make the office smell like a nail salon. Bis-acryls, like Access Crown from Centrix, don’t have that effect.
Related to the toxicity of methyl-methacrylates, concerns have been raised regarding their potential toxicity in dental use, both for the patient and also in the workplace.
In an in vitro study1, MMA leached from some dental appliances appear toxic to cells and may cause local mucosal irritation or even an allergic reaction. Dentists and other dental staff exposed to MMA in the dental clinic appear to occasionally suffer hypersensitivity, asthmatic reactions, local neurological symptoms, and irritant and local dermatological reactions. The integrity of latex gloves may also be compromised after exposure to MMA during dental procedures, the study found. The authors concluded that techniques should be employed to reduce patients' exposure to MMA during dental procedures in order to reduce the risks of possible complications, and dental staff should avoid direct contact with MMA and room ventilation should be optimized.
A different study3 found that bis-acryl resins were cytocompatible with human gingival fibroblasts, suggesting that both materials studied were suitable for use in contact with human tissues.
Which material would you rather use on your patients?
Advanced fillers and fluorescence have improved the strength2 and esthetics of bis-acryl-polished restorations. Traditionally, that hasn’t always been the case, but dentists are seeing beautiful results with contemporary materials.
In Dr. Hopper’s experience with modern materials like Access Crown, bis-acryls are “initially more esthetic and provide better color stability than traditional acrylics.” He also found that shade matching is not a problem for Access Crown, as it’s available in 7 VITA shades plus Bleach shades, and it polishes very easily. “It offers excellent translucency compared to some of the other products as well,” he added.
The sense of touch relates to both the clinician’s handling of the material and its placement. Bis-acryl materials, like Access Crown, offer a lower exothermic setting temperature than methacrylates, as well as lower polymerization shrinkage. According to Dr. Hopper, there is no significant shrinkage with Access Crown, so relining is not necessary, and there is little chance of getting a provisional “locked on” the preparation. Centrix adds that the material removes easily from the mouth in 60 seconds without distortion.
When it comes to handling, Dr. Hopper found that Access Crown offers advantages over some of the other bis-acryls currently available. It’s packaged in the 1:1 format cartridge, instead of a 10:1 format cartridge, so it will work in most high-pressure dispensing guns, he explained. Access Crown uses a smaller "Supermixer" mixing tip, so there is less waste of the material, which means dentists are getting as many as 38 additional units per cartridge. Access Crown has one of the fastest setting times available, less than 1 minute, preventing what he calls “dreaded wait times.”
While this sensory description might be a stretch considering we’ve discussed a temporary material and not a handpiece, there is something to be said about the patient’s ability to chew in peace after this procedure. In a promotion for Access Crown, Centrix even says, “Chew on this — high compressive and flexural strength means long-lived restorations.” In Dr. Hopper’s experience, Access Crown has a higher fracture toughness than many other bis-acryl brands, nearly eliminating broken temporaries.
Considering Access Crown’s ease of use, shade selection, fast set, and competitive cost, it’s become one of Dr. Hopper’s materials of choice for the fabrication of well-fitting, strong, and esthetic provisional crowns and bridges.
In the video below, watch a clinical case where a 5-unit bridge was fabricated with Access Crown. You can learn more at www.centrix.com.
1. Leggat PA, Kedjarune U. Toxicity of methyl methacrylate in dentistry. Int Dent J. 2003 Jun;53(3):126-31.
2. Babcic V, Perry R, Kugel G. Material toughness. AADR Abstract 2008:0371.
3. Gonçalves FP, Alves G, Guimarães VO Júnior, Gallito MA, Oliveira F, Scelza MZ. Cytotoxicity Evaluation of Two Bis-Acryl Composite Resins Using Human Gingival Fibroblasts. Braz Dent J. 2016 Sep-Oct;27(5):492-496.