Mark Cannon

In situ evaluation of the remineralizing capacity of pit and fissure sealants containing amorphous calcium phosphate and/or fluoride

Abstract Objective. This in situ study evaluated the remineralizing potential of pit and fissure sealants containing amorphous calcium phosphate (ACP) and/or fluoride in artificially induced carious lesions on smooth enamel surfaces. Material and methods. Ten volunteers who wore acrylic palatal devices were enrolled in this 5-day double-blind study and assigned to one of the following five groups: (I) demineralized enamel slab+Fluroshield (sealant with fluoride); (II) demineralized enamel slab+Aegis (sealant with ACP); (III) demineralized enamel slab+experimental sealant with fluoride (ESF); (IV) demineralized enamel slab+experimental sealant with fluoride/ACP (ACP-F); and (V) demineralized enamel slab (control). After the experimental period, the percentage of surface microhardness recovery (%SMHR) and the integrated loss of subsurface hardness (ΔKHN) were evaluated. The concentrations of fluoride, calcium and phosphorus in enamel were also determined. Results. The sealants containing ACP and/or fluoride presented a higher remineralizing capacity (%SMHR and ΔKHN) than that of the control group. Aegis provided either more efficient or similar remineralization than the other sealants. The association between ACP and fluoride did not show a greater efficacy in the remineralization. F, Ca and P concentrations in enamel varied according to the group. Conclusion. The pit and fissure sealants containing ACP were able to promote remineralization of artificially induced carious lesions on smooth enamel surfaces.

Evaluation of alveolar socket response to Angelus MTA and experimental light-cure MTA

OBJECTIVE The aim of this study was to evaluate the rat alveolar socket response to implanted polyethylene tubes filled with a light-cured MTA or Angelus MTA. STUDY DESIGN Fifty-seven Wistar rats received an implant filled with one of the materials in the dental socket of the right central incisor. After 30, 60, and 90 days, animals were killed, and the right hemimaxillas were removed and processed to be analyzed on light microscopy. After embedding in paraffin, 6-μm-thick sections were obtained and stained with hematoxylin and eosin. Qualitative and quantitative analyses of the reaction were performed. RESULTS It was observed that the light-cured MTA presented a similar response compared with Angelus MTA, characterized by the reduction of the chronic inflammatory response and organization of the alveolar bone close to the materials, especially at the 90th day of observation. CONCLUSIONS It was concluded that both materials were well accepted by the alveolar tissue of rats, with the formation of mineralized tissue close to the materials.

Effect of pH variations in a cycling model on the properties of restorative materials.

This study evaluated the effect of cycling various pH demineralizing solutions on the surface hardness, fluoride release and surface properties of restorative materials (Ketac-Fil Plus, Vitremer, Fuji II LC, Freedom and Fluorofil). Thirty specimens of each material were made and the surface hardness measured. The specimens were randomized into five groups according to the pH (4.3; 4.6; 5.0; 5.5 and 6.2) of the demineralizing solution. The specimens were submitted to pH-cycling for 15 days. The specimens remained in the demineralizing solution for six hours and in the remineralizing solution for 18 hours. Then, the surface hardness (SH) was remeasured and the surface properties were assessed. Fluoride release was determined daily. Data from SH and the percentage of alteration in surface hardness were analyzed by analysis of variance (p < 0.05); the Kruskal-Wallis test was performed for the fluoride release results. When hardness was compared, the variation in pH led to a positive correlation for glass ionomer cements and a negative correlation for fluoride release. For polyacid-modified resin composites, a negative correlation was found with regards to fluoride release; no significant correlation was observed for hardness. Surface properties were influenced: an acidic pH led to a greater alteration, except for polyacid-modified resin composites. The pH of the demineralizing solution influenced fluoride release from the tested materials. The pH variation altered hardness and surface properties of glass ionomer cements but did not influence polyacid-modified resin composites.

Microhardness and fluoride release of restorative materials in different storage media

This study evaluated the surface microhardness and fluoride release of 5 restorative materials - Ketac-Fil Plus, Vitremer, Fuji II LC, Freedom and Fluorofil - in two storage media: distilled/deionized water and a pH-cycling (pH 4.6). Twelve specimens of each material, were fabricated and the initial surface microhardness (ISM) was determined in a Shimadzu HMV-2000 microhardness tester (static load Knoop). The specimens were submitted to 6- or 18-h cycles in the tested media. The solutions were refreshed at the end of each cycle. All solutions were stored for further analysis. After 15-day storage, the final surface microhardness (FSM) and fluoride release were measured. Fluoride dose was measured with a fluoride-specific electrode (Orion 9609-BN) and digital ion analyzer (Orion 720 A). The variables ISM, FSM and fluoride release were analyzed statistically by analysis of variance and Tukeys test (p<0.05). There was significant difference in FSM between the storage media for Vitremer (pH 4.6 = 40.2 +/- 1.5; water = 42.6 +/- 1.4), Ketac-Fil Plus (pH 4.6 = 73.4 +/- 2.7; water = 58.2 +/- 1.3) and Fluorofil (pH 4.6 = 44.3 +/- 1.8; water = 38.4 +/- 1.0). Ketac-Fil Plus (9.9 +/- 18.0) and Fluorofil (4.4 +/- 1.3) presented higher fluoride release in water, whereas Vitremer (7.4 +/- 7.1), Fuji II LC (5.7 +/- 4.7) and Freedom (2.1 +/- 1.7) had higher fluoride release at pH 4.6. Microhardness and fluoride release of the tested restorative materials varied according to the storage medium.

Surface resistance to abrasion of preformed laminate resin veneers

Preformed laminate resin veneers should be adapted closely to the teeth to reduce the thickness of the composite layer. Minimal voids at the composite, veneer, and tooth junctional margin will result. Composite resins are difficult to finish, but laminate veneer can be highly polished. Poorly finished veneer surfaces appear to abrade to a smoother surface with toothbrushing while poorly finished composite surfaces remain rough. To reduce material loss from abrasion, the veneer restoration should be highly polished. Polishing the veneer at the gingival margin is particularly important to gingival health. Only rough veneer surfaces will be improved by toothbrushing abrasion. Special instructions should be given to patients with laminated veneers to reinforce proper oral hygiene and to discourage use of highly abrasive dentifrices. Continued monitoring of plaque accumulation should minimize problems related to oral hygiene.

A Review of Probiotic Therapy in Preventive Dental Practice

Probiotics have been widely publicized in the general press and the consumer media. Knowledge of the existence of “probiotics” is commonplace, and the effectiveness of probiotic therapy has been well reported in the medical literature. However, even though most published dental studies have reported positive results, the dental profession has not yet accepted the use of probiotic therapy as an adjunct for preventive dental care. This review article discusses published and current research into the applications of probiotics along with diagnostic testing of the oral biofilm. Probiotic therapy appears to be generally safe and effective in modifying with beneficial bacteria the oral biofilm and thereby reducing the effects of pathogenic oral bacteria. In this review, some examples of current oral probiotic research are discussed along with reference to the potential application of diagnostic testing of the oral biofilm for the presence of oral pathogens as a precursor to initiation of specific probiotic therapy. Dental professionals should be actively investigating this potentially very useful therapeutic measure for the benefit of their patients.

Quantitative analysis of mineral content in enamel using laboratory microtomography and microhardness analysis

This study evaluates laboratory microtomography and microhardness analysis for quantifying the mineral content of bovine enamel. Fifty enamel blocks were submitted individually for 5 days to a pH-cycling model at 37°C and remained in the remineralizing solution for 2 days. The blocks were treated twice daily for 1 min with NaF dentifrices (Placebo, 275, 550, 1,100 μg F/g and Crest(R)) diluted in deionized water. Surface microhardness changes (%SMH) and mineral loss (ΔZ) were then calculated. Laboratory microtomography was also used to measure total mineral lost (LMM). Pearsons correlation (p<0.05) was used to determine the relationship between different methods of analysis and dose-response between treatments. Dentifrice fluoride concentration and %SMH and ΔZ were correlated (p<0.05). There was a positive relationship (p<0.05) when comparing LMM vs. ΔZ; a negative relationship (p<0.05) was found for %SMH vs. LMM and %SMH vs. ΔZ. Therefore, both mineral quantification techniques provide adequate precision for studying the bovine enamel-pH-cycling demineralization/remineralization model.

Oral manifestations of malignant histiocytosis (histiocytic medullary reticulosis)

Abstract This article describes the case of a 2-year-old boy with symptoms of an “eruption hematoma” who was ultimately found to have oral involvement by malignant histiocytosis. The therapy and dental management that followed are presented.

In vitro effect of amorphous calcium phosphate paste applied for extended periods of time on enamel remineralization

Abstract Dental applications based on the unique characteristics of amorphous calcium phosphate stabilized by casein phosphopeptides (CPP-ACP) have been proposed, as well as the improvement of its properties. Objectives: The objective of this study was to determine the ability of topically applied CPP-ACP from a commercial product to remineralize subsurface lesions when applied for extended periods of time (3 h and 8 h). Material and Methods: Artificially induced carious lesions were produced in 50 bovine enamel blocks previously selected by surface hardness. After treatments with gel without F and CPP-ACP applied for 1 minute (Placebo); 2% NaF neutral gel applied for 1 minute (Fluoride 1 min); CPP-ACP applied for 3 min (ACP 3 min); and CPP-ACP applied for 3 h (ACP 3 h) and for 8 h (ACP 8 h), the enamel blocks were submitted to the remineralization pH-cycling. Surface hardness and synchrotron micro-tomography were used to determine the percentage of surface hardness recovery (%SHR) and to calculate mineral concentration (gHAp.cm−3), respectively. The data were submitted to ANOVA followed by the Student-Newman-Keuls test (p<0.05). Results: Fluoride gel presented higher %SHR followed by ACP 3 min (p<0.001). No difference (p = 0.148) was found for Placebo, ACP 3 h and ACP 8 h groups for %SHR. Fluoride gel showed greater mineral concentration (p<0.001) when compared with the other groups. ACP 3 min demonstrated a significant difference (p<0.001) from ACP 3 h and ACP 8 h. The ACP 3 h and 8 h presented a subsurface lesion with development of laminations in all blocks. Conclusion: In this in vitro study the use of CPP-ACP for extended periods of time did not produce an additive effect in the remineralization process.

Analysis of Anticaries Potential of Pit and Fissures Sealants Containing Amorphous Calcium Phosphate Using Synchrotron Microtomography

The aim of this study was to analyze the anticaries potential of pit and fissure sealants containing amorphous calcium phosphate (ACP) by synchrotron microtomography. Bovine enamel blocks (4×4 mm; n=50) were selected through surface hardness (Knoop) analysis. Slabs were obtained through cross-sections taken 1 mm from the border of the enamel. Five indentations, spaced 100 μm apart, were made 300 μm from the border. Ten specimens were prepared for each tested material (Ultraseal XT plus TM, Aegis, Embrace, Vitremer and Experimental Sealant). The materials were randomly attached to the sectioned surfaces of the enamel blocks and fixed with sticky wax. The specimens were submitted to pH cycling. After that, the surface hardness (SH1) was determined, and the blocks were submitted to synchrotron microcomputed tomography analysis to calculate the mineral concentration (ΔgHAp cm(-3)) at different areas of the enamel. The comparison between the SH1 and ΔgHAp cm(-3) showed a correlation for all groups (r=0.840; p<0.001). The fluoride groups presented positive values of ΔgHAp cm(-3), indicating a mineral gain that was observed mainly in the outer part of the enamel. The ACP showed mineral loss in the outer enamel compared with fluoride groups, although it inhibited the demineralization in the deeper areas of enamel. The combination of two remineralizing agents (fluoride and ACP) was highly effective in preventing demineralization.