Effect of intermittent delivery of fluoride to solution on root hard-tissue de- and remineralization measured by 125I absorptiometry

Recombinant amelogenin peptide TRAP promoting remineralization of early enamel caries: An in vitro study

Objective: To explore the regulatory effect of recombinant amelogenin peptide TRAP on the remineralization of early enamel carious lesions. Methods: Forty-eight bovine enamel blocks that prepared initial lesions in vitro were split at random into four groups for immersion treatment for 12 days: 1) remineralizing medium; 2) studied peptide 1 (consisting of the N- and C-termini of porcine amelogenin) + remineralizing medium; 3) studied peptide 2 (TRAP) + remineralizing medium; 4) fluoride + remineralizing medium. After demineralization and remineralization immersion, each specimen's mean mineral loss and lesion depth were measured using micro-computed tomography (micro-CT). The changes in lesion depth (∆LD) and mineral gain (∆Z) were computed following remineralization. The enamel samples were then cut into sections and examined with polarized light microscopy (PLM). The cross-section morphology was observed by scanning electron microscopy (SEM). The crystal phase was analyzed by an X-ray micro-diffractometer (XRD). The calcium-binding properties were determined using isothermal titration calorimetry (ITC). Results: Micro-CT analysis revealed a significant reduction in mineral loss in the four groups following the remineralization treatment (p < 0.05). The treatment with fluoride resulted in the greatest ∆Z and ∆LD, whereas the treatment with a remineralizing medium showed the least ∆Z and ∆LD among all groups. The ∆Z and ∆LD of the studied peptide 1 and studied peptide 2 groups were greater than those of the remineralizing medium group. However, there was no significant difference between the studied peptide 1 and studied peptide 2 groups (p > 0.05). All of the samples that the PLM analyzed had a thickening of the surface layer. A negative birefringent band changed in the lesion's body. The SEM displayed that minerals were formed in all four groups of samples. The XRD results indicated that the products of remineralization of the studied peptide were hydroxyapatite crystals (HA). ITC showed that there were two binding modes between the calcium and peptide TRAP. Conclusion: This study confirmed the potential of the recombinant amelogenin peptide TRAP as a key functional motif of amelogenin protein for enamel remineralization and provided a promising biomaterial for remineralization in initial enamel carious lesion treatment.

Effect of three different remineralizing agents on artificial erosive lesions of primary teeth

BACKGROUND

This study aimed to investigate the efficacy of three remineralizing agents on dental erosion in primary teeth.

METHODS

Forty primary molars were randomly divided into four groups (n = 10 each): self-assembling peptide (P_11-4 ), casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACFP), sodium fluoride (NaF) and artificial saliva (AS; control). The erosion-like formation was created by immersing the samples in citric acid (4 × 2 min, pH 2.3) and AS (4 × 2 h, pH 7). The eroded samples were then treated with remineralizing agents and subjected to further erosion consisting of 15 cycles (3x/8-h interval) of immersion in citric acid and AS for 6 s each. Alterations in the mineral content and morphology of the samples were quantified using a microhardness tester and atomic force microscope.

RESULTS

All agents had a significant remineralization effect on eroded primary tooth enamel. After further erosive challenge, enamel loss in the CPP-ACFP group was found to be significantly lower than in all other groups, and no significant difference was found between the P_11-4 and NaF groups.

CONCLUSIONS

This study showed that all tested materials had remineralization ability, and CPP-ACFP had a superior effect in inhibiting enamel loss due to dental erosion in primary teeth. © 2022 Australian Dental Association.

Effect of mouthwashes on the discoloration of bracket-bonded tooth surfaces: an in vitro study

OBJECTIVES

This in vitro study aimed to investigate the color changes of the bracket-bonded tooth surfaces after the use of 4 different mouthwashes.

MATERIALS AND METHODS

A total of 100 human premolar teeth were randomly divided into 10 equal groups. Color values (L*a*b*) of the buccal surfaces of each tooth were assessed using a digital spectrophotometer. Then the brackets were bonded. The groups were put either in sterile saline (4 test+1 control) or artificial saliva (4 test+1 control) solutions, and test groups were immersed in their mouthwashes (Colgate Plax, Listerine Cool Mint, Klorhex, and Tantum Verde) for 1 min each in the morning/evening to simulate the mouth washing for 21 days after the bonding. After the debonding and finishing procedures, final color measurements were performed. Color changes (∆E) were calculated.

RESULTS

All of the parameters showed statistically significant differences among the groups. The least noticeable color changes were detected in the control groups. The most noticeable color change (ΔE) was observed in the Tantum Verde + artificial saliva group, followed by Tantum Verde + sterile saline and Klorhex + artificial saliva groups, all of which were significantly higher than the control groups.

CONCLUSION

The use of mouthwashes during orthodontic treatment may cause noticeable changes in tooth color. Listerine Cool Mint may be the choice of mouthwash with its less discoloring effects. Artificial saliva should be preferred in similar in vitro studies to reflect the oral environment better.

CLINICAL RELEVANCE

Mouthwash use during orthodontic treatment may result in different levels of enamel discoloration.

A pilot study of the effects of a vacuum sealing barrier method for photostimulable phosphor plates regarding plate damage and prevention of microbiologic cross-contamination

OBJECTIVE

The aim of this study was to evaluate the effectiveness of a new sealing method for preventing cross-contamination of photostimulable phosphor (PSP) plates.

STUDY DESIGN

Twelve new PSP plates were divided into 3 groups (PSP-a, PSP-b, and PSP- c) and placed in 3 different barriers (2 different brands of envelopes and a vacuum sealing method). All plates were exposed to X-rays with an aluminum step wedge, and the images were evaluated for the presence of any artifacts. After radiography, the PSP plates were removed from the barriers. The barriers and the PSP plates were disinfected and culture performed to assess any microorganism burden. Subsequently, the PSP plates were coated again with all barriers. The barriers were then contaminated and microbiologic specimens were collected. Subsequently, the barriers were wiped with alcohol. The PSP plates were removed, and microbiologic specimens were obtained.

RESULTS

No artifacts were recorded on the radiographic images on the sensors in any group. Microorganisms were detected on the PSP plates placed in envelopes. No colonization of microorganisms was detected on the vacuum sealed PSP plates.

CONCLUSIONS

The new vacuum-sealing method may be useful in preventing cross-contamination of PSP plates during radiographic procedures.

The role of fluoride and chlorhexidine in preserving hardness and mineralization of enamel and cementum after gamma irradiation

The purpose of this study was to evaluate the effect of 0.05% sodium fluoride and 0.12% chlorhexidine mouthwashes on the micro-hardness of tooth enamel and cementum that was exposed to therapeutic doses of gamma radiation. Sixty extracted human teeth were divided into two groups, one was irradiated, the other was not irradiated. The two groups were further subdivided into three subgroups, which were each treated either with 0.05% sodium fluoride or with 0.12% chlorhexidine; the third subgroup served as a control. After demineralization-remineralization cycling, teeth from the irradiated groups showed a significantly lower micro-hardness when compared to those from the non-irradiated groups. Both in the irradiated and non-irradiated groups, teeth from the control subgroups showed a significantly lower micro-hardness, as compared to teeth treated with sodium fluoride and chlorhexidine. For non-irradiated enamel samples, those treated with chlorhexidine showed a significantly less micro-hardness compared to those treated with sodium fluoride. In contrast, irradiated enamel showed no significant difference in micro-hardness, whatever treatment (chlorhexidine or sodium fluoride) was applied. For cementum, treatment with chlorhexidine resulted in a significantly lower micro-hardness compared to sodium fluoride, both for the irradiated and non-irradiated groups. It is concluded that gamma irradiation with therapeutic doses typically used for head and neck carcinoma treatment has a direct effect in reducing micro-hardness of tooth enamel and cementum. Mouthwash protocols including, for example, application of 0.05% sodium fluoride or 0.12% chlorhexidine three times per day for 6 weeks, can protect enamel and cementum against the reduction in hardness and demineralization caused by gamma irradiation. Sodium fluoride offers more protection compared to chlorhexidine.

The application of in vitro models to research on demineralization and remineralization of the teeth

Progress in in vivo and in situ experimentation has led many researchers to speculate as to the relevance and importance of in vitro testing protocols in caries research. A Medline/Biosis search for the present review revealed well over 300 citations (since 1989) documenting in vitro tests associated with caries research on mineralization and fluoride reactivity. The present survey documents these recent applications of in vitro test methods in both mechanistic and 'profile' caries research. In mechanistic studies, in vitro protocols over the past five years have made possible detailed studies of dynamics occurring in mineral loss and gain from dental tissues and the reaction dynamics associated with fluoride anticaries activity. Similarly, in profile applications, in vitro protocols make possible the inexpensive and rapid--yet sensitive--assessment of F anticaries efficacy within fluoride-active systems, and these tests represent a key component of product activity confirmation. The ability to carry out single variable experiments under highly controlled conditions remains a key advantage in in vitro experimentation, and will likely drive even further utilization, as advances continue in physical-chemical and analytical techniques for substrate analysis in these protocols. Despite their advantages in vitro testing protocols have significant limitations, most particularly related to their inability to simulate the complex biological processes involved in caries.