Evaluation of the chemical, physical, and biological properties of a newly developed bioceramic cement derived from cockle shells: an in vitro study

BACKGROUND

Tricalcium silicate is the main component of commercial bioceramic cements that are widely used in endodontic treatment. Calcium carbonate, which is manufactured from limestone, is one of the substrates of tricalcium silicate. To avoid the environmental impact of mining, calcium carbonate can be obtained from biological sources, such as shelled mollusks, one of which is cockle shell. The aim of this study was to evaluate and compare the chemical, physical, and biological properties of a newly developed bioceramic cement derived from cockle shell (BioCement) with those of a commercial tricalcium silicate cement (Biodentine).

METHODS

BioCement was prepared from cockle shells and rice husk ash and its chemical composition was determined by X-ray diffraction and X-ray fluorescence spectroscopy. The physical properties were evaluated following the International Organization for Standardization (ISO) 9917-1;2007 and 6876;2012. The pH was tested after 3 h to 8 weeks. The biological properties were assessed using extraction medium from BioCement and Biodentine on human dental pulp cells (hDPCs) in vitro. The 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5[(phenylamino)carbonyl]-2 H-tetrazolium hydroxide assay was used to evaluate cell cytotoxicity following ISO 10993-5;2009. Cell migration was examined using a wound healing assay. Alizarin red staining was performed to detect osteogenic differentiation. The data were tested for a normal distribution. Once confirmed, the physical properties and pH data were analyzed using the independent t-test, and the biological property data were analyzed using one way ANOVA and Tukey's multiple comparisons test at a 5% significance level.

RESULTS

The main components of BioCement and Biodentine were calcium and silicon. BioCement's and Biodentine's setting time and compressive strength were not different. The radiopacity of BioCement and Biodentine was 5.00 and 3.92 mmAl, respectively (p < 0.05). BioCement's solubility was significantly higher than Biodentine. Both materials exhibited alkalinity (pH ranged from 9 to 12) and demonstrated > 90% cell viability with cell proliferation. The highest mineralization was found in the BioCement group at 7 days (p < 0.05).

CONCLUSIONS

BioCement exhibited acceptable chemical and physical properties and was biocompatible to human dental pulp cells. BioCement promotes pulp cell migration and osteogenic differentiation.

Factors associated with dental caries experience of Thai preschool children with cerebral palsy

AIM

To investigate the factors association with dental caries experience in the primary dentition of Thai preschool children with cerebral palsy.

METHODS AND RESULTS

A cross-sectional study was conducted among sixty Thai preschool children with cerebral palsy, aged 3-6 years old. Caries experience was determined by identifying decayednon-cavitated and cavitated lesion, missing, and filled surfaces of deciduous teeth(dmfs). Sociodemographic data, CP motor types, dietary habits, oral health behaviors and dental plaque index were collected. Multiple linear regression analysis was carried out to identify the strength of the association between factors and dental caries experience. The prevalence of dental caries was 91.66%. The average dmfs was 20.30 ± 21.63 surfaces/individual. The multiple linear regression indicated that dmfs was significantly associated with snacking carbohydrate between meals more than two times/day (β ± SE = 0.372 ± 0.125; p = 0.004), spastic type of cerebral palsy (β ± SE = 0.309 ± 0.124; p = 0.015) and one-time daily tooth brushing (β ± SE = 0.306 ± 0.124; p = 0.017).

CONCLUSIONS

Nine out of 10 preschool children with CP experienced dental caries. Spastic type of CP had more risk to develop dental decay. Caries prevention for preschool children with CP should emphasis on controlling the frequency of carbohydrate snack no more than two times/day and reinforcing tooth brushing at least twice daily.

Reinforcement of Simulated Immature Permanent Teeth after Mineral Trioxide Aggregate Apexification

OBJECTIVES

The objectives of this study were to compare the fracture resistance of simulated human immature teeth that have undergone mineral trioxide aggregate (MTA) apexification and have been root-filled with fiber post, composite resin, MTA, or gutta-percha.

METHODS

Fifty-six human permanent maxillary incisors were selected. Ten teeth received no treatment (intact teeth group). The root canals of 46 teeth were prepared to an internal diameter of 1.75 mm. Six teeth were used as simulated immature teeth group. The remaining teeth received MTA apexification and were divided into 4 groups: MTA, fiber post, composite resin, and gutta-percha groups. The root canals of each group were filled with each test material. All teeth were thermocycled and received cyclic loading before compression testing by an Instron universal testing machine. The load to fracture was recorded. Data were subjected to statistical analysis by using one-way analysis of variance and Tukey multiple comparison test.

RESULTS

All teeth fractured at the cervical area of the root. The mean load to fracture of the intact tooth, MTA, fiber post, composite resin, gutta-percha, and the simulated immature tooth groups was 1988 N, 1921 N, 1691 N, 1623 N, 1476 N, and 962 N, respectively. Statistically, load to fracture of the simulated immature tooth group was significantly lower than in the intact tooth, MTA, fiber post, and composite resin groups but was not significantly different from the gutta-percha group.

CONCLUSIONS

Within the limit of this study, after MTA apexification, intraradicular reinforcement with MTA, fiber post, or composite resin increased the fracture resistance of simulated immature teeth.

Self-etch or etch-and-rinse mode did not affect the microshear bond strength of a universal adhesive to primary dentin

This study evaluated the microshear bond strength (µSBS) of resin composite to primary dentin using a universal adhesive in etchand-rinse mode or self-etch mode. Flat ground dentin surfaces were created on forty extracted human primary incisors and randomly assigned into four groups (n=10): Adper Single Bond II (ASB), Clearfil SE Bond (CSE), Single Bond Universal etch-and-rinse (SBUER) and Single Bond Universal self-etch (SBU-SE). Adhesive was applied on the dentin surface, which was subsequently bonded with a resin composite. The µSBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The ASB group generated a lower mean µSBS (19.1±3.4 MPa) than those of the other groups [SBU-ER (24.3±2.7 MPa), SBU-SE (25.1±2.4 MPa), and CSE (25.3±2.7 MPa)]. Adhesive failure was the most common failure mode in each group. In conclusion, SBU used in etch-and-rinse or self-etch mode resulted in similar bond strength to primary dentin.

Silver diamine fluoride and glass ionomer differentially remineralize early caries lesions, in situ

OBJECTIVES

The aim of the present study was to evaluate the percent mean mineral density (MD) change of early caries lesions after the application of silver diamine fluoride (SDF) or glass ionomer cement (GIC).

MATERIALS AND METHODS

This double-blind, crossover study involved two experimental phases of 28 days each. Thirty-two pairs of enamel slabs were created from the proximal surfaces of 16 premolars. Each pair of artificial carious slabs was randomly divided into the control or test group (38 % SDF or GIC). The slabs were attached to orthodontic brackets and bonded to the maxillary first permanent molars of 16 subjects for 28 days. After a 7-day washout period between phases, the subjects received the other material for the second phase. The mean MD of the lesions was measured by microcomputed tomography.

RESULTS

SDF yielded a percent mean MD increase at a depth of 0-84 μm, although increase in the GIC group was observed at a depth of 24-108 μm. The percent mean MD changes of the SDF and GIC groups were similar (p = 0.100) and significantly higher than in control (p < 0.001, p = 0.003, respectively).

CONCLUSIONS

The two materials increased the percent mean MD change of early proximal caries lesions to a similar extent, but with different spatial patterns.

CLINICAL RELEVANCE

Due to deeper level of GIC remineralization, the refractive index of the GIC applied enamel might be closer to sound enamel. Hence, GIC is recommended for remineralization of anterior teeth. SDF staining makes it unsuitable for use in anterior teeth; thus, it is reserved for use in posterior teeth.

Use of a disclosed plaque visualization technique improved the self-performed, tooth brushing ability of primary schoolchildren

BACKGROUND

Disclosing agents have a long history of use as an aid in children's tooth brushing instruction. However, their benefit when used to improve self-performed tooth brushing ability without any tooth brushing instruction has not been investigated.

OBJECTIVE

To evaluate the effect of disclosed plaque visualization on improving the self-performed, tooth brushing ability of primary school children.

MATERIAL AND METHOD

A cluster-randomized, crossover study was conducted in Nakhon Nayok province, Thailand. A total of 122 second-grade schoolchildren, aged 8-10 years old, from 12 schools were randomly divided into 2 groups. The first group was assigned to brush with disclosed plaque visualization, while the other group brushed without disclosed plaque visualization. One month later the groups switched procedures. Tooth brushing ability was evaluated by the subjects' reduction in patient hygiene performance (PHP) scores. The data were analyzed using repeated-measures analysis of variance, with significance set at p<0.05.

RESULTS

Disclosed plaque visualization had a significant effect on improving the children's self-performed, tooth brushing ability in all areas of the mouth (p<0.001), particularly for anterior teeth, mandibular teeth, buccal surfaces, and areas adjacent to the gingival margin (p<0.001).

CONCLUSION

Disclosed plaque visualization is a viable technique to improve children's self-performed tooth brushing ability, and could be used in school-based oral health promotion programs.