Erosive cola-based drinks affect the bonding to enamel surface: an in vitro study

Objective

This study aimed to assess the impact of in vitro erosion provoked by different cola-based drinks (Coke types), associated or not with toothbrushing, to bonding to enamel.

Material and Methods

Fifty-six bovine enamel specimens were prepared and randomly assigned into seven groups (N=8): C- Control (neither eroded nor abraded), ERO-RC: 3x/1-minute immersion in Regular Coke (RC), ERO-LC: 3x/1-minute immersion in Light Coke (LC), ERO-ZC: 3x/1-minute immersion in Zero Coke (ZC) and three other eroded groups, subsequently abraded for 1-minute toothbrushing (EROAB-RC, EROAB-LC and EROAB-ZC, respectively). After challenges, they were stored overnight in artificial saliva for a total of 24 hours and restored with Adper Single Bond 2/Filtek Z350. Buildup coronal surfaces were cut in 1 mm² -specimens and subjected to a microtensile test. Data were statistically analyzed by two-way ANOVA/Bonferroni tests (α=0.05). Failure modes were assessed by optical microscopy (X40). The interface of the restorations were observed using Confocal Laser Scanning Microscopy (CLSM).

Results

All tested cola-based drinks significantly reduced the bond strength, which was also observed in the analyses of interfaces. Toothbrushing did not have any impact on the bond strength. CLSM showed that except for Zero Coke, all eroded specimens resulted in irregular hybrid layer formation.

Conclusions

All cola-based drinks reduced the bond strength. Different patterns of hybrid layers were obtained revealing their impact, except for ZC.

Effect of simulated intraoral erosion and/or abrasion effects on etch-and-rinse bonding to enamel

PURPOSE

To assess the influence of simulated oral erosive/abrasive challenges on the bond strength of an etch-and-rinse two-step bonding system to enamel using an in situ/ex vivo protocol.

METHODS

Bovine enamel blocks were prepared and randomly assigned to four groups: CONT - control (no challenge), ABR - 3x/day-1 minute toothbrushing; ERO - 3x/day - 5 minutes extraoral immersion into regular Coca Cola; and ERO+ABR - erosive protocol followed by a 1-minute toothbrushing. Eight blocks were placed into an acrylic palatal appliance for each volunteer (n = 13), who wore the appliance for 5 days. Two blocks were subjected to each of the four challenges. Subsequently, all the blocks were washed with tap water and Adper Single Bond 2/Filtek Z350 were placed. After 24 hours, 1 mm2 beams were obtained from each block to be tested with the microtensile bond strength test (50 N load at 0.5 mm/minute). The data were statistically analyzed by one-way RM-ANOVA and Tukey's tests (alpha = 0.05).

RESULTS

No difference was detected among the ABR, ERO, and CONT groups (P > 0.05). ERO+ABR group yielded lower bond strengths than either the ABR and ERO groups (P < 0.0113).

Color degradation of acrylic resin denture teeth as a function of liquid diet: ultraviolet-visible reflection analysis

The effect of different beverages on acrylic resin denture teeth color degradation is evaluated. Ten acrylic resin denture teeth brands were evaluated: Art Plus (AP), Biolux (BX), Biotone IPN (BI), Magister (MG), Mondial 6 (MD), Premium 6 (PR), SR Vivodent PE (SR), Trilux (TR), Trubyte Biotone (TB), and Vipi Dent Plus (VP). Teeth were immersed in staining solutions (coffee, cola, and orange juice) or artificial saliva (control) (n=6) for 1, 7, 15, or 30 days. Specimen colors were evaluated spectrophotometrically based on the Commission Internationale d'Eclairage L*a*b* system. Color differences (ΔE) were calculated between the baseline and post-staining results. Data were evaluated by analysis of variance and Tukey test (α = 0.05). BI (1.82 ± 0.95) and TR (1.78 ± 0.72) teeth exhibited the greatest ΔE values, while BX (0.88 ± 0.43) and MD (1.09 ± 0.44) teeth were the lowest, regardless of solution and measurement period, and were different from BI and TR teeth (P < 0.05). Cola and coffee promoted higher denture teeth color alterations than orange juice and saliva (P < 0.05). Saliva generated the lowest denture teeth color alterations. Greater immersion times caused higher denture teeth color changes. The lifespan of removable dentures and the aesthetic satisfaction of several edentulous patients may be increased with the use of stain-resistant artificial denture teeth.