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PubMedDate not supplied

Demineralization around orthodontic brackets bonded with resin-modified glass ionomer cement and fluoride-releasing resin composite.

PURPOSE: Enamel demineralization adjacent to orthodontic brackets is one of the risks associated with orthodontic treatment. Glass ionomer cements have been shown to decrease enamel demineralization adjacent to brackets and bands but do not exhibit bond strengths comparable to resin composites. The purpose of this in vitro study was to compare a fluoride-releasing resin composite versus a resin-modified glass ionomer cement for inhibition of enamel demineralization surrounding orthodontic brackets. METHODS: Forty-five teeth were randomly assigned to 3 groups of 15 teeth. Fifteen were bonded with Concise (3M), a non-fluoride-releasing resin composite (control); 15 teeth were bonded with Light Bond (Reliance), a fluoride-releasing resin composite; and 15 teeth were bonded with Fuji Ortho LC (GC Corporation), a resin-modified glass ionomer cement. The teeth were placed in an artificial caries solution to create lesions. Following sectioning of the teeth in a buccolingual direction, polarized light microscopy was utilized to evaluate enamel demineralization adjacent to the orthodontic bracket. The area of the lesion was measured 100 microns from the orthodontic bracket and bonding agent. RESULTS: MANOVA (P < .0001) and Duncan's test (P < .05) indicated the resin-modified glass ionomer cement (Fuji Ortho LC) and the fluoride-releasing resin composite (Light Bond) had significantly less adjacent enamel demineralization than the non-fluoride-releasing resin composite control. However, there was no significant difference between the resin-modified glass ionomer cement and the fluoride-releasing resin composite. CONCLUSIONS: Based on the results of this in vitro study, it can be concluded that Fuji Ortho LC and Light Bond exhibit significant inhibition of adjacent demineralization compared to the non-fluoride-releasing control.

Acrylic Resins↗
PubMed2000

Microhardness changes in surface enamel after application of bioadhesive fluoride tablets in situ.

The effect of fluoride released by bioadhesive tablets was evaluated in an in situ model in human volunteers. Eight volunteers carried four to six polished human enamel samples in a lower lingual device for a period of 5 days without fluoride supplements (control) and 5 days using one bioadhesive tablet (0.5 mg F) per day, placed in the lower buccal sulcus. Changes in mineral content were measured in terms of surface microhardness indentation length (load 0.98 N, Knoop diamond indenter). Some enamel samples were analyzed for their fluoride content by means of a surface etch biopsy. The indentation length increased significantly in both experiments, but demineralization was less pronounced with fluoride (indentation length increased from 44 +/- 7 to 48 +/- 13 microns) than in the control (44 +/- 7 to 58 +/- 13 microns). The fluoride concentration and the amount of calcium in the acid etch biopsy specimens of the enamel samples did not differ significantly between the two groups. Bioadhesive, fluoride-releasing tablets have therefore demonstrated the potential to reduce demineralization by elevating salivary and plaque fluoride concentration for a period of several hours. This self-administered device can be a supplementary means for prevention of caries.

Adhesives↗
PubMed2003

An in vitro assessment using transverse microradiography of the effect on mineral loss of etching enamel for in situ studies.

OBJECTIVES: To test the hypothesis that etching enamel with 37% phosphoric acid for 30 s does not lead to detectable mineral loss when measured with transverse microradiography (TMR). DESIGN: An in vitro laboratory investigation. EXPERIMENTAL VARIABLE: Forty bovine incisors were used in the experiment. The crowns of the teeth were covered with acid resistant varnish except for a rectangular area on the labial surface approximately 10 x 12 mm. On the exposed labial surface of 20 teeth an enamel lesion similar to that used in the in situ caries model was induced. Twenty teeth were left without a lesion. The exposed area was divided into three areas of equal size. The control area (C) was covered with acid resistant varnish throughout the experiment. The first experimental area (E1) was etched with 37% phosphoric acid for 30 s and a simulated bracket was bonded to the surface with composite resin. The second experimental area (E2) was left exposed for the remainder of the experiment. The teeth were placed in a demineralizing solution for 24, 48, 72 or 96 h to replicate different cariogenic challenges. OUTCOME MEASURE: Mineral loss as measured with TMR. RESULTS: There were no significant differences in the mineral loss between etched (E1) and etched (C) areas of enamel. There were significant differences in mineral loss between E1 and E2 for the 48 h (p < 0.001) and 72 h (p = 0.001) exposures without a pre-formed enamel lesion. CONCLUSION: There is no detectable mineral loss with TMR when enamel has been etched for 37% phosphoric acid for 30 s. The use of in situ enamel specimens with acid etch retained simulated brackets to investigate demineralization during orthodontics will not significantly affect the outcome compared with unetched specimens.

Acid Etching, Dental↗
PubMed1992

An in vitro model for assessment of fluoride uptake from glass-ionomer cements by dentin and its effect on acid resistance.

This investigation presents an experimental model for studying interactions of glass-ionomer cements (GICs) with bovine dentin slabs. Fluoride incorporation was studied with five serial abrasion biopsies, each being approximately 10 microns thick. The time of interaction was a very important parameter, indicating continuous fluoride release from the GIC and diffusion into dentin over a 30-day period. Expressed in mass per volume (mg F/cm3), the fluoride incorporation reached 12.0 mg at the first and 2.5 mg at the fifth layer, several times greater than the baseline of 0.27 mg/cm3 in bovine dentin. A subsequent test of acid resistance in a lactic acid buffer (pH 4.0), followed by microradiography of lesions, showed a characteristic 40-microns-wide acid-resistant zone on surfaces exposed to the GICs. In contrast, the untreated control surfaces had lesions demineralized evenly from the surface to the intact tissue, without the higher-density zone at the surface of the lesion. The model seems promising for screening fluoride incorporation into dentin from fluoride-releasing dental materials.

Animals↗
PubMed2006

[Some causes of systemic demineralization of dental solid tissues in children of early age].

Among the risk factors causing generalized demineralisation of dental solid tissues in young kids (disturbances during antenatal development of embryo, frequent sickness of infant, etc.) the most important factor is the type of breath feeding of infant. Such factors as the good balance of calcium and phosphor in mother's milk contribute to the maintenance of healthy dental tissues. As our data shows in majority of kids (98%) with artificial feeding type, calcium and phosphorus levels in the blood serum and their rate (<1.30) were decreased, along with that hydrogen ion concentration in oral fluids was also decreased. All above mentioned has influence on physical-chemical reactions occurring in tooth enamel, increases enamel penetration and reduces buffer characteristics of oral fluids. Those problems are especially important for Georgia, where the level of fluoride in the drinking water is very low (0.35-0.45 mg/l).

Calcium↗
PubMed1994

Effects of aluminum (III) and fluoride on the demineralization of bovine enamel: a longitudinal microradiographic study.

Longitudinal microradiography has been used to determine inhibiting effects of aluminum (III), Al, and fluoride on mineral loss from slices of bovine enamel exposed to a demineralizing solution 4 h daily for 35 days. Inhibitor treatment was 5 min four times daily. For the remaining time, the samples were immersed in a neutral calcium phosphate solution which allowed neither remineralization nor demineralization. This study indicates that a 1-mM (27 ppm) solution of Al in a 0.1-M lactate solution, pH 5, has an inhibitory effect on the in vitro demineralization of bovine enamel. Application of this solution alternating with 20 mM (380 ppm) fluoride gave the same total inhibition as treatment with 20 mM fluoride alone.

Alum Compounds↗
PubMed1998

An in vitro comparison between laser fluorescence and visual examination for detection of demineralization in occlusal pits and fissures.

It has been demonstrated that when excited by laser light carious enamel appears dark compared to luminescent sound enamel. The aim of this study was to compare the sensitivity and specificity of visual exams (V), laser fluorescence (LF) and dye-enhanced LF (DELF) for detecting demineralization in occlusal pits and fissures. The actual presence of lesions was determined by subsequent confocal laser microscopy (CM), which was compared to histology (H). Independent clinical examiners visually graded three sites on occlusal surfaces of extracted, human premolars as sound or carious and also rated the color of each graded site as: 0 = same as surrounding enamel; 1 = white; 2 = light brown, or 3 = brown/dark brown. An argon laser was used to illuminate the teeth for LF and DELF; the images were captured with a CCD camera and then analyzed. DELF images were captured after the teeth had been exposed to 0.075% sodium fluorescein. Sections were then cut from each specimen and analyzed by CM and H for the presence or absence of caries. Results showed that DELF (0.72) was significantly more sensitive (p<0.05) than LF (0.49) and V (0.03) for detecting caries, but there were no significant differences among the methods in specificity (V 1.00; LF 0.67; DELF 0.60). When color was used as an indication of caries in V (VC, sensitivity 0.47; specificity 0.70), V exams were not different from LF. The area under the ROC curve, using H as the gold standard and CM as the test, was 0.78. Results indicated that DELF was the best diagnostic tool and that VC and LF were equally effective as diagnostic methods, when color of fissures was included as an indication of demineralization in the visual exam.

Argon↗
PubMed1992

Limitations in the intraoral demineralization of bovine enamel.

A model system was used to examine the relation between the duration of plaque pH fall and enamel demineralization following the intake of dietary carbohydrate in humans. Subjects wore palatal appliances containing blocks of bovine enamel covered with Streptococcus mutans IB 1600, and rinsed with 5 or 10% sucrose. Changes in iodide penetrability (delta Ip) of the enamel, and the pH and extracellular calcium and inorganic phosphate (Pi) concentrations of the streptococcal plaque were determined. Following rinses with 5% sucrose, delta Ip increased with time and reached a maximum (11.2 +/- 2.2 units) at 45-60 min although the S. mutans plaque remained acidic (pH = 4.8 +/- 0.6). After 10% sucrose, the maximum (14.7 +/- 3.1 units) was reached while the plaque pH was 4.0 +/- 0.3. Second rinses with sucrose increased delta Ip at most by 30%. Thus, demineralization did not persist throughout the period of low plaque pH, but occurred primarily during the early phase of plaque acidogenesis. Enamel demineralization appeared to be limited by factors other than the pH of the streptococcal plaque. Calcium concentrations in the S. mutans plaque rose to a maximum of 10.9 +/- 2.8 mEq/l at 30 min after the 5% sucrose rinses, then fell; Pi reached a stable level of 12.2 +/- 2.3 mEq/l by 60 min. Calculations showed that conditions approached saturation with respect to enamel and dicalcium phosphate dihydrate as demineralization reached a maximum. Demineralization appeared to be limited at low plaque pH, therefore, by the accumulation of high levels of mineral ions in the streptococcal plaque.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2002

Sequence of ultrastructural changes of enamel crystals and Streptococcus mutans biofilm in early enamel caries in vitro.

Undecalcified mature enamel sections were used to observe the sequence of ultrastructural changes of enamel crystals and Streptococcus mutans biofilm in the early stages of caries. Human enamel blocks were incubated from 1 to 7 days with S. mutans suspension, and the pH of biofilm was measured. They were processed for light microscopic and transmission electron microscopy observations, and the number of bacteria located in the area adjacent to enamel surface counted. It was observed that the pH of the biofilm dropped to 4, after 1-day of incubation and the S. mutans number increased until 4-day. Round shaped enamel crystals were observed in the 2-day specimens and from the 4-day, images of crystals showing defects and perforations were visualized, becoming more defective along the incubation days. The length of time that the enamel was exposed to biofilm was the main factor for enamel crystals demineralization. Current in vitro caries induction system could standardize time-related changes of the property of Streptococcus mutans biofilm and its relation to enamel crystals demineralization at the ultrastructural level, and thus provide a useful model for the evaluation of the effects of various anti-cariogenic agents.

Biofilms↗
PubMed2003

Enamel demineralization inhibition by cements at orthodontic band margins.

PURPOSE: To examine the demineralization inhibition effects of glass ionomer cement and polyacid-modified resin-based composite cement, in comparison to non-fluoride releasing zinc phosphate cement. METHODS: Twenty-seven extracted molars were obtained and randomly assigned to three groups. An orthodontic band was sized and cemented using one of three cements. The teeth were painted with an acid-protective varnish, excluding a 1 mm area gingival to the orthodontic band. The teeth were placed in separate closed environments of a non-fluoridated acid challenge to induce demineralization for 5 days. The teeth were then sectioned two times buccolingually and two times mesiodistally. The sections were photographed with polarized light microscopy in an imbition media of water. The body of each lesion was measured with a computerized imaging system. The areas of the lesions, from each cement group, were compared. RESULTS: An analysis of variance (ANOVA) indicated significance in variance among groups (P < 0.001). Results of a multiple comparison analysis demonstrated significantly less demineralization adjacent to the glass ionomer cement group compared with the polyacid-modified resin cement group and non-fluoride releasing zinc phosphate control group (P < 0.05). There was no significant difference in adjacent demineralization inhibition between the zinc phosphate cement group and polyacid-modified resin cement group (P < 0.05).

Analysis of Variance↗
PubMed2004

Penetration of a bonding agent into De- and remineralized enamel in vitro.

PURPOSE: To evaluate bonding penetration into different enamel substrates. MATERIALS AND METHODS: Ten extracted human molars were mesiodistally sectioned. Buccal and lingual enamel surfaces were divided into four equal areas using sticky wax. The central two areas of each tooth (n = 20) were demineralized for 12 weeks using an acidic gel (pH 4.8). The lateral areas served as controls. After demineralization, ten specimens were remineralized in a saliva substitute for three weeks. An amine fluoride solution (Elmex Fluid) was applied on one half of each specimen before acid etching. After etching for 120 s, an enamel-bonding agent (Heliobond) containing 0.1% rhodamine was applied onto test and control areas, and was light cured for 60 s. Subsequently, the specimens were sectioned and tag length was determined using a confocal laser scanning microscope (CLSM). Results were statistically compared with ANOVA followed by Scheffe's and Bonferroni/Dunn post hoc tests. RESULTS: With a mean penetration depth of 68 +/- 22 microm, tags in demineralized enamel were significantly longer than in other groups (p < or = 0.01). Penetration decreased significantly in remineralized areas or when fluoride was used (p < or = 0.01), but was still significantly deeper than in control sites (p < or = 0.01). CONCLUSION: Penetration of an unfilled resin into enamel was considerably influenced by the degree of dental hard tissue mineralization. Penetration was increased in demineralized enamel; however, remineralized enamel also allowed good penetration of the bonding agent.

Acid Etching, Dental↗
PubMed2005

Inhibition of dentine demineralization by zinc oxide: in vitro and in situ studies.

OBJECTIVE: The objective of this study was to evaluate the inhibitory effect of zinc oxide on dentine demineralization in vitro and in situ. METHODS: In the in vitro study, dentine specimens treated with a zinc oxide suspension were demineralized in a pH 5 solution. In the in situ study, subjects wore dentine specimens on their teeth and instructed to rinse with zinc-containing toothpaste slurry three times a day for 14 days. The design of study was a crossover one. RESULTS: Microradiography employed in the in vitro study revealed the dentine surfaces treated with distilled water had a lower mineral content than those treated by zinc. Toothpaste with zinc had a statistically significant, 49% greater inhibitory efficacy on dentine demineralization over the control. In the in situ study, zinc-containing toothpaste was also confirmed to have an inhibitory effect on dentine demineralization when compared to the zinc-free toothpaste. These in vitro and in situ studies revealed that zinc oxide can have a significant effect on the inhibition of dentine demineralization, even when the zinc oxide is blended into toothpaste. SIGNIFICANCE: This suggests that zinc oxide may be effective in the prevention of root caries.

Adult↗
PubMed2005

Mandibular incisal edge demineralization and caries associated with Twin Block appliance design.

Demineralization and caries are well documented and unwanted complications of orthodontic therapy. These are most commonly reported in relation to fixed appliance therapy. Five cases are presented of patients undergoing Twin Block appliance therapy with the appliances incorporating lower labial segment capping, illustrating a pattern of demineralization and caries of the incisal tips of the mandibular labial segment, influenced by the incisal capping and the frequent intake of carbonated soft drinks.

Adolescent↗
PubMed2002

In vivo bracket retention comparison of a resin-modified glass ionomer cement and a resin-based bracket adhesive system after a year.

Glass ionomer orthodontic adhesives cause less enamel demineralization during fixed orthodontic appliance treatment than do traditional resin-based products. An in vivo randomized clinical trial was performed comparing the clinical performance of a resin-modified glass ionomer (RMGI) adhesive with a no-mix, resin-based (the control) adhesive over a 12-month period. The split-mouth technique was used to analyze bracket retention, bracket failure causes, and mode of failure for both adhesives in 61 patients. Bracket-failure rates were 10% for the RMGI and 4% for the resin-based adhesive. Both adhesives had 4 times more bracket failures when opposing occlusion was present. The resin-based product demonstrated a higher proportion of resin-to-enamel adhesive failures than did the RMGI. Compared with the resin-based adhesive, the RMGI-bracketed teeth showed improved clinical performance, no enamel surface loss, less enamel demineralization, and faster adhesive removal. However, the RMGI had a 2.6 times greater bracket-failure rate than did the resin-based product.

Adolescent↗
PubMedDate not supplied

Inhibition of lesion progression by the penetration of resins in vitro: influence of the application procedure.

This study compared the progression of sealed initial enamel lesions penetrated with a fissure sealant (Helioseal, Vivadent) or various adhesives (Heliobond, Excite, Vivadent; Resulcin, Merz; Solobond M, Voco; Prompt L-Pop, 3M-ESPE) after exposure to a demineralizing solution, in vitro. From 27 bovine teeth, 54 enamel specimens were prepared and covered with nail varnish (control), thus obtaining three windows for treatment. After demineralization (pH 5.0; 14 days), two of the windows (A, B) were etched with phosphoric acid (20%; 5 seconds); whereas, the third area served as the control (C). The specimens were divided randomly into six groups (n=9), and the material was applied (90 seconds) either once (A) or twice (B). Light-curing followed each application. Half of the area of each specimen window was then covered with nail varnish, and the samples were again stored in the demineralizing solution (pH 5.0; 14 days). The specimens were cut perpendicular to the surface, and both enamel slabs were studied after infiltration using a fluorescent, low viscous resin (VIRIN) and confocal microscopy (CLSM). Lesion depths were calculated (ImageJ) from the surface to that point in the lesion where the grey values clearly changed to a darker grey. After demineralization, mean lesion depths (SD) (14 days) were measured at 105 (21) microm. The second demineralization led to a mean progression of the lesion depths of 52 (31)%. Adper Prompt L-Pop and Solobond M could not significantly prevent lesion progression after a single application (p > 0.05; t-test); however, the second application of Solobond M significantly decreased lesion progression (p < 0.05; t-test). Helioseal, Heliobond, Resulcin Monobond and Excite showed significantly better inhibition of the demineralization compared to the other materials (p < 0.05; Bonferroni). It can be concluded that the penetration of adhesives into initial lesions inhibited a further demineralization in vitro.

Acid Etching, Dental↗
PubMed2002

Comparative age study of the risk of demineralization during orthodontic treatment with brackets.

AIM: The aim of the study was to investigate the hypothesis of a higher risk of demineralization in regions adjacent to brackets at earlier age. METHODS: A prospective cohort study of 42 persons (22 persons aged 11-15 years and 20 persons aged 19-24 years) in the process of orthodontic treatment with brackets was performed. The duration of the observation was 18 months. The object of evaluation were 508 vestibular surfaces of permanent teeth that had brackets fixed. The statistical analysis included non-parametric analysis and comparison of percentages. The attributive risk (AR) and the relative risk (RR) were also determined. RESULTS: After removal of brackets, 51.61% of the surfaces of the 11-15 year olds showed demineralization. In the 19-24 year age group this result was 6.92%. The difference was statistically significant (P < 0.001). The attributive risk was 86.59% and the relative risk was 7.45%. This indicates that age is a risk factor for demineralization adjacent to brackets. CONCLUSION: The results of the study support the hypothesis of a higher risk of demineralization in regions adjacent to brackets at earlier age. This is a direct consequence of the lower resistance of the dental tissues and the poorer cooperation from the younger patients in the orthodontic treatment process.

Adolescent↗
PubMed1995

An SEM examination of etched dentin and the structure of the hybrid layer.

The clinical requirements of dentin bonds are that they should be non-permeable to oral fluids, seal dentinal tubules, protect the pulp, and be long lasting and durable. Dentin bonding systems that use acidic agents to remove the smear layer are currently being used. Acid conditioning not only removes the smear layer, but also demineralizes the surface of the intertubular dentin and produces intratubular demineralization and funnelling. A dentin bond is produced when hydrophillic resin monomers infiltrate the dentinal tubules and collagen of the demineralized intertubular zone, producing a hybrid layer. The use of a critical point drying technique and SEM allows a clear visualization of the structure of the hybrid layer. This study showed that currently used hydrophillic resin monomers are unable to completely infiltrate the demineralized zone, and it is speculated that this failure could contribute to microleakage and influence the long-term durability of the bond. It is also apparent that these bonds depend on the mechanical investment of collagen by the infiltrating monomer. Since none of the unfilled resins tested seem capable of completely infiltrating the demineralized collagenous zone, the degree of demineralization produced by the commercial acid concentrations in current use is questioned. More dilute acids than those available commercially are shown to reduce both the degree and depth of demineralization, and we suggest that the resultant thinner layer may lend itself to more complete resin infiltration of the collagen.

Acid Etching, Dental↗