Influence of removing excess of resin-based materials applied to eroded enamel on the resistance to erosive challenge.

OBJECTIVES: The aim of this study was to evaluate the effect of removing excess of resin-based materials applied to eroded enamel, subjected to erosive challenge. METHODS: Bovine enamel blocks were immersed in HCl 0.01M, pH 2.3, for 30s under agitation at 50 rpm in room temperature, in order to form a softened erosion lesion. The blocks were then randomly divided into eight groups (n=12) and treated as follows: Cn- and Ce-control without treatment, Hn- and He-fissure resin sealant (Helioseal Clear(®)), An- and Ae-self-etch adhesive (Adhese(®)), In- and Ie-infiltrant (Icon(®)); being n-with excess removal and e-without excess removal of the material. After application of the materials, the blocks were immersed in HCl for 2 min, followed by immersion in artificial saliva for 120 min. This cycle was repeated four times a day for five days. Material thickness and enamel wear were assessed using profilometry. Data were analyzed by two-way ANOVA and Tukey's test (P<0.05). RESULTS: Groups He, Ae, and Ie resulted in the formation of a layer of material over enamel, being similar effective in inhibiting erosion progression (P>0.05). Groups Hn, An, and In (with excess removal) were similar to controls (Cn, Ce) and resulted in near enamel loss after application and after erosive challenge (P>0.05). CONCLUSIONS: Resin-based materials are able to protect enamel against erosion only when they are present over enamel, as a physical barrier. CLINICAL SIGNIFICANCE: The resin-based materials demonstrated potential to prevent the progression of erosion lesions when the material remains on the dental surface.

In situ effect of a commercial CPP-ACP chewing gum on the human enamel initial erosion.

OBJECTIVE: This study evaluated the in situ rehardening effect of a commercial chewing gum containing casein phosphopeptide - amorphous calcium phosphate (CPP-ACP) on initial erosion lesions. METHODS: Seventy-two human enamel blocks, after selection (initial surface hardness - SHi) and in vitro short-term acidic exposure (cola drink for 3 min - SHd) were randomly assigned to three groups. The factors under study were treatment (3 levels: GI chewing gum with CPP-ACP, GII chewing gum without CPP-ACP and GIII control group without gum) and intraoral period (2 levels: 2 and 24h). Twelve volunteers wore intraoral palatal devices for 24h in 3 crossover phases. On each phase, after 2h the surface hardness was assessed (SHf1) and the blocks were reinserted and the devices were used for additional 22 h (SHf2). In phases of GI and GII volunteers chewed the respective gum during 30 min, for 4 times with an interval of 4h. Percentage of surface hardness recovery (%SHR) was calculated after 2 and 24 h. The data were analysed by repeated measures ANOVA and Tukey's test. RESULTS: Chewing gum with CPP-ACP (2h=50.0%<24h=95.9%) showed higher hardness recovery than chewing gum without CPP-ACP (2h=30.0%<24 h=71.1%) and control (2 h=15.7%<24 h=40.9%) (p<0.05). CONCLUSIONS: The results suggest that saliva increased hardness of softened enamel after the use of conventional chewing gum (GII) and this effect was enhanced by the prolonged intraoral period (24 h) and by the use of CPP-ACP chewing gum (GI). CLINICAL SIGNIFICANCE: Since chewing gum is an alternative to enhance salivary defenses after erosive challenges, CPP-ACP chewing gum might be a supplementary strategy to potentiate the mineral precipitation of initial erosion lesions.

Photodynamic inactivation of Candida albicans mediated by a low density of light energy.

Shorter times and lower energies of application of light sources are desirable to use photodynamic antimicrobial chemotherapy (PACT) to the clinical control of candidiasis, especially among babies and children. Light energies ranging from 39.5 to 100 J/cm(2) were previously applied to kill Candida albicans by PACT. The present study evaluated the efficacy of a combination of 0.05 mg/mL toluidine blue O (TBO) and a short time of application (60 s) and a low density of light energy (18 J/cm(2)) of a red light-emitting diode (LED) in killing C. albicans planktonic cells. Standard suspensions of C. albicans were randomly assigned for four treatment groups: control (L-P-), LED alone (L+P-), TBO alone (L-P+), and PACT (L+P+). After treatments, serial dilutions of suspensions were prepared and streaked on Sabouraud dextrose agar to determine colony-forming units of C. albicans per milliliter (CFU/mL). The results were analyzed by ANOVA and Tukey's post-hoc test (P < 0.05). PACT significantly reduced CFUs of C. albicans in comparison to other three treatments. Our results demonstrated a fungicidal effect of PACT mediated by a shorter time of application of LED on C. albicans planktonic cells. Further in vivo studies are needed to elucidate the efficacy of PACT to treat human fungal infections.

An in situ/ex vivo comparison of the ability of regular and light colas to induce enamel wear when erosion is combined with abrasion.

OBJECTIVE: To evaluate whether the type of cola drink (regular or diet) could influence the wear of enamel subjected to erosion followed by brushing abrasion. METHOD AND MATERIALS: Ten volunteers wore intraoral devices that each had eight bovine enamel blocks divided into four groups: ER, erosion with regular cola; EAR, erosion with regular cola plus abrasion; EL, erosion with light cola; and EAL, erosion with light cola plus abrasion. Each day for 1 week, half of each device was immersed in regular cola for 5 minutes. Then, two blocks were brushed using a fluoridated toothpaste and electric toothbrush for 30 seconds four times daily. Immediately after, the other half of the device was subjected to the same procedure using a light cola. The pH, calcium, phosphorus, and fluoride concentrations of the colas were analyzed using standard procedures. Enamel alterations were measured by profilometry. Data were tested using two-way ANOVA and Bonferroni test (P<.05). RESULTS: Regarding chemical characteristics, light cola presented pH 3.0, 13.7 mg Ca/L, 15.5 mg P/L, and 0.31 mg F/L, while regular cola had pH 2.6, 32.1 mg Ca/L, 18.1 mg P/L, and 0.26 mg F/L. The light cola promoted less enamel loss (EL, 0.36 Μm; EAL, 0.39 Μm) than its regular counterpart (ER, 0.72 Μm; EAR, 0.95 Μm) for both conditions. There was not a significant difference (P>.05) between erosion and erosion plus abrasion for light cola. However, for regular cola, erosion plus abrasion resulted in higher enamel loss than erosion alone. CONCLUSION: The data suggest that light cola promoted less enamel wear even when erosion was followed by brushing abrasion.

Dental erosion in a group of 12- and 16-year-old Brazilian schoolchildren.

PURPOSE: This study's purpose was to assess the prevalence of dental erosion in adolescents and to investigate the association between erosion and sociodemographic characteristics. METHODS: This study consisted of a single center cluster random sample of 414 adolescents (12 and 16 years old) of both genders from private and public schools in Bauru, São Paulo, Brazil. Two previously calibrated examiners (kappa=0.85) used the O'Brien (1994) index for assessment of dental erosion on the buccal and palatal surfaces of the permanent maxillary incisors and on the occlusal surfaces of the permanent first molars. Data on gender, type of school, and mean family income were collected by a questionnaire completed by the adolescents. Descriptive statistics were applied to the data, and the associations between erosion and sociodemographic variables were investigated by chi-square test (P<0.05). RESULTS: The prevalence of dental erosion was 20% (N=83), with only enamel being involved (score 1). The labial surface was the most affected (16%). There were no significant differences between the presence of erosion and gender, type of school, and mean family income. CONCLUSIONS: The results indicate that dental erosion restricted to enamel was observed among adolescents in Bauru/Brazil, and there was no correlation between this condition and sociodemographic factors.

Light cola drink is less erosive than the regular one: an in situ/ex vivo study.

OBJECTIVE: This in situ/ex vivo study assessed the erosive potential of a light cola drink when compared to a regular one. METHODS: During 2 experimental 14-days crossover phases, eight volunteers wore palatal devices with 2 human enamel blocks. The groups under study were: group light, erosive challenge with light cola drink and group regular, erosive challenge with regular cola drink. During 14 days, erosive challenges were performed extraorally 3X/day. In each challenge, the device was immersed in 150ml of light cola (group light) or regular cola (group regular) for 5min. Erosion was analysed by surface profilometry (microm) and surface microhardness change (%SMH). The data were statistically analyzed using paired t test (p<0.05). RESULTS: Group light (0.6+/-0.2microm) showed significantly lesser wear than group regular (3.1+/-1.0microm). There was no significant difference between the groups for the %SMH (group light -63.9+/-13.9 and group regular -78.5+/-12.7). CONCLUSIONS: The data suggest that the light cola drink is less erosive than the regular one.

In situ effect of an erosive challenge on different restorative materials and on enamel adjacent to these materials.

OBJECTIVES: This in situ study evaluated the effect of an erosive challenge on different restorative materials and on enamel restored with these materials, as well as the ability of these materials to protect the adjacent enamel against erosion. METHODS: Ten volunteers wore palatal devices with eight bovine enamel blocks, randomly selected and distributed into two vertical rows, corresponding to the following groups: GI/GV, resin-modified glass ionomer; GII/GVI, conventional glass ionomer; GIII/GVII, composite resin; GIV/GVIII, amalgam. One row (corresponding to groups I-IV) was immersed in a cola drink and the other row (corresponding to groups V-VIII) was subjected to saliva only. The palatal device was continuously worn for 7 days and only half of the appliance (groups I-IV) was immersed in the soft drink (Coca-Cola), 150 mL) for 5 min, three times a day. The study variables comprised the wear (profilometry, microm) and the percentage of surface microhardness change (%SMHC). Data were tested for significant differences by two-way ANOVA and Tukey's tests (p<0.05). RESULTS: Considering the restorative materials, for %SMHC and wear, there were no differences among the materials and between the saliva and the erosive challenge. For enamel analyses, the erosive challenge promoted a higher wear and %SMHC of the enamel than did the saliva. There were no significant differences in wear and %SMHC of the enamel adjacent to the different restorative materials. CONCLUSION: This research data suggest that there is little %SMHC and wear of the studied restorative materials and none of them had a preventive effect against erosion on adjacent enamel, which showed a pronounced wear.

Evaluation of the erosive potential of soft drinks.

OBJECTIVES: This in vitro study evaluated the capability of different soft drinks (Coca-Cola(R)-C, Coca-Cola Light(R)-CL, Guaraná(R)-G, Pepsi Twist(R)-P and Sprite Light(R)-SL) to erode dental enamel, relating the percentage of superficial microhardness change (%SMHC) to concentrations of fluoride and phosphate, buffering capacity and pH of these drinks. METHODS: The soft drinks were evaluated in respect to concentration of phosphate and fluoride spectrophotometrically using Fiske, Subarrow method and by specific electrode (Orion 9609), respectively. The pH and the buffering capacity were determined by glass electrode and by estimating of the volume of NaOH necessary to change the pH of the drink in one unit, respectively. One hundred specimens of bovine enamel were randomly assigned to 5 groups of 20 each. They were exposed to 4 cycles of demineralisation in the beverage and remineralisation in artificial saliva. The softening of enamel was evaluated by %SMHC. RESULTS: The mean %SMHC was: C=77.27%, CL= 72.45%, SL=78.43%, G=66.65% and P=67.95%. Comparing the %SMHC promoted by 5 soft drinks, SL = C > CL > P = G (P<.05). There was not significant correlation between %SMHC and the other variables tested for the five drinks (P>.05). CONCLUSIONS: The five soft drinks caused surface softening of enamel (erosion). In respect to the chemical variables tested, despite not statistically significant, the pH seems to have more influence on the erosive potential of these drinks. (Eur J Dent 2007;1:10-13).