July/August 2013, Volume 34, Issue 7
Published by AEGIS Communications
Compendium has compiled Abstracts from key recently published articles in the dental literature on adhesive dentistry. These PubMed-indexed articles offer clinical relevance to the dental practitioner and can be applied to a range of situations.
Effectiveness and biological compatibility of different generations of dentin adhesives
Bond strength and biocompatibility are both highly significant properties of dentin adhesives. These properties of four generations of adhesive systems (Multi-Purpose/Single Bond/SE Plus/Easy Bond) were evaluated. Eighty bovine teeth had their dentin exposed (500- and 200-μm thickness). Adhesive was applied on the dentin layer of each specimen, then the microshearing test was performed for all samples. A dentin barrier test was used for the cytotoxicity evaluation. Cell cultures (SV3NeoB) were collected from testing materials by means of 200- or 500-μm-thick dentin slices and placed in a cell culture perfusion chamber. Cell viability was measured 24 h post-exposition by means of a photometrical test (MTT test). The best bonding performance was shown by the single-step adhesive Easy Bond, followed by Single Bond, SE Plus, and Multi-Purpose. The one-step system showed the best bond strength performance and was the least toxic to pulp cells. In multiple-step systems, a correct bonding technique must be done, and a pulp capping strategy is necessary for achieving good performance in both properties. The study showed a promising system (one-step self-etching), referring to it as a good alternative for specific cases, mainly due to its technical simplicity and good biological responses.
Proanthocyanidins rapidly stabilize the demineralized dentin layer
While proanthocyanidins (PA) are effective in improving collagen’s resistance to collagenolytic degradation, the direct incorporation of PA into an adhesive system is detrimental to the light-curing thereof. Conversely, the use of PA as a primer could circumvent this issue, but little is known about the efficacy of PA in stabilizing collagen when applied in a clinically relevant manner. This study investigated the pre- and post-digestion morphology of an acid-etched dentin collagen layer that underwent PA treatment for time periods on a scale of seconds. The null hypothesis, that there is no difference between the PA-treated and untreated control group, had to be rejected, since it was revealed that the untreated control could not survive 1 h of exogenous collagenase digestion, while the PA-treated collagen could sustain at least 16 h of digestion with no perceptible changes in collagen structure. In addition, the stabilizing effect of the gold-standard cross-linker glutaraldehyde at comparable experimental conditions was found to be almost non-existent within the 5, 15, or 30 sec of cross-linking permitted. Therefore, PA have been proven to be extraordinarily efficient in stabilizing demineralized dentin collagen against enzymatic challenges in a clinically relevant setting, likely due to the non-covalent nature of their interaction with collagen molecules.
Chlorhexidine release from orthodontic adhesives after topical chlorhexidine treatment
This study was designed to investigate the ability of orthodontic adhesives to adsorb and release chlorhexidine (CHX) after periodic treatment with 1% CHX solution. Composite and resin-modified glass-ionomer cement (RM-GIC) adhesive disks were incubated with whole saliva or distilled water for 2 h. Release of CHX was measured using high-performance liquid chromatography after 1, 2, and 5 d of incubation, 1 min after exposure to 1% CHX solution. The CHX measurements were performed in a 5-d cycle, which was repeated four consecutive times (n = 7). The amount of CHX adsorbed and the cumulative amounts of CHX released, with respect to type of adhesive and saliva-coating, were analyzed using repeated-measures ANOVA. Chlorhexidine-adsorbed orthodontic adhesives demonstrated a short-term release of CHX, which rapidly returned to near-baseline levels within 3 d. Saliva-coating did not significantly influence CHX release from RM-GIC, but increased the amount of CHX released from the composite. This study suggests that composite adhesives may be a significantly more effective CHX reservoir than RM-GICs in the oral cavity filled with saliva.