[Repair of mandibular defects with hydrogel loaded with nano-hydroxyapatite in rats].

PURPOSE: To observe the effect of gellan gum loaded with nano-hydroxyapatite (GG/nHA) on repairing mandibular defect in rats. METHODS: Critical bone defects with 5 mm in diameter on the mandible of 16 SD rats were created and randomly divided into two groups. The bone defects in the experimental group were injected with GG/nHA and the control group were filled with absorbable gelatin sponge. The rats were sacrificed at 4 and 8 weeks after operation. The bone tissue healing was evaluated by Micro-CT. Bone tissue repairing effect was evaluated by hematoxylin-eosin (H-E) staining and Masson staining. GraphPad Prism 8.0 software package was used for statistical analysis. RESULTS: The prepared GG/nHA had a good injectability and could be delivered to the bone defect area with a syringe. Four and 8 weeks after operation, the newly formed bone and bone volume fraction (BV/TV) in the experimental group were higher than those in the control group, and the difference was statistically significant (P<0.05). Larger number of new bone were observed in the experimental group than the control group by H-E staining and Masson staining. CONCLUSIONS: GG/nHA can be injected into the mandibular defect area to promote its healing, and it is expected to be used as a novel bio-material for minimally invasive repair of oral and maxillofacial bone defects.

Secondary bile acids mediate high-fat diet-induced upregulation of R-spondin 3 and intestinal epithelial proliferation.

A high-fat diet (HFD) contributes to the increased incidence of colorectal cancer, but the mechanisms are unclear. We found that R-spondin 3 (Rspo3), a ligand for leucine-rich, repeat-containing GPCR 4 and 5 (LGR4 and LGR5), was the main subtype of R-spondins and was produced by myofibroblasts beneath the crypts in the intestine. HFD upregulated colonic Rspo3, LGR4, LGR5, and ß-catenin gene expression in specific pathogen-free rodents, but not in germ-free mice, and the upregulations were prevented by the bile acid (BA) binder cholestyramine or antibiotic treatment, indicating mediation by both BA and gut microbiota. Cholestyramine or antibiotic treatments prevented HFD-induced enrichment of members of the Lachnospiraceae and Rumincoccaceae, which can transform primary BA into secondary BA. Oral administration of deoxycholic acid (DCA), or inoculation of a combination of the BA deconjugator Lactobacillus plantarum and 7α-dehydroxylase-containing Clostridium scindens with an HFD to germ-free mice increased serum DCA and colonic Rspo3 mRNA levels, indicating that formation of secondary BA by gut microbiota is responsible for HFD-induced upregulation of Rspo3. In primary myofibroblasts, DCA increased Rspo3 mRNA via TGR5. Finally, we showed that cholestyramine or conditional deletion of Rspo3 prevented HFD- or DCA-induced intestinal proliferation. We conclude that secondary BA is responsible for HFD-induced upregulation of Rspo3, which, in turn, mediates HFD-induced intestinal epithelial proliferation.

Caries experience in individuals with cleft lip and/or palate in China.

OBJECTIVE: To determine the levels of dental caries in subjects with cleft lip and/or palate in China in comparison with controls. DESIGN: A total of 380 subjects with cleft lip and/or palate and 339 non cleft control subjects were examined for dental caries using the decayed-missing-filled-teeth (DMFT/dmft) and decayed-missing-filled-surfaces (DMFS/dmfs) index. A questionnaire was used to acquire subjects' living habits and family socioeconomic status. SETTING: West China Stomatology Hospital, Sichuan University. SUBJECTS: Individuals between 3 and 25 years of age. RESULTS: Caries prevalence and scores for dmft/DMFT and dmfs/DMFS were significantly higher in subjects with cleft palates when compared with the non cleft control group (p < .05), except 3- to 5-year-old children (p > .05). However, in the 3- to 5-year-old group, children with cleft lip and/or palate had significantly more caries than children of the same age with only a cleft lip with or without alveolus (p < .05). Children whose clefts had been surgically repaired had a lower dmft and dmfs than those whose clefts had not been surgically repaired (p < .05). CONCLUSION: Individuals with oral cleft are at an increased risk for dental caries. The types of cleft and the surgical repair are two important factors for dental caries.

[Role of enamel organic matrix in the remineralization of initial demineralized enamel and artificial hydroxylapatite treated with Galla chinensis].

OBJECTIVE: To observe the remineralization of initial demineralized enamel and artificial hydroxylapatite treated with Galla chinensis in vitro, and to assess the effect of enamel organic matrix on the potential of Galla chinensis to promote the remineralization of initial enamel carious lesions, further to elucidate the mechanism of Galla chinensis in promoting the remineralization of initial enamel carious lesion. METHODS: Bovine sound enamel blocks, non-organic enamel blocks and artificial hydroxylapatite blocks were demineralized and exposed to a pH-cycling. During the pH-cycling, the specimens were randomly treated with 1 g/L NaF, 4 g/L Galla chinensis extract (GCE) or double deionized water (DDW). Surface microhardness of all the samples was measured before and after the pH-cycling, and percentage surface microhardness recovery (% SMHR) was calculated. The surface morphology was observed by scanning electron microscopy. RESULTS: A significant increase in microhardness (P < 0.05) with many irregular deposits and prominences on GCE treated regular enamel blocks were observed. No significant increase in that of the regular enamel treated with DDW, enamel disposed of its organic matrix or artificial hydroxylapatite treated with GCE were observed (P > 0.05). No obvious changes in the SEM images of regular enamel treated with DDW, enamel disposed of its organic matrix or artificial hydroxylapatite treated with GCE compared to those of them before pH-cycling. CONCLUSION: Galla chinensis enhances the remineralization of initial enamel carious lesions in vitro. The organic matrix of enamel was shown to play a substantial role in the observed mechanism.

[Effects of various surface treatments on the bonding efficacy of noncarious cervical sclerotic lesions].

Noncarious cervical sclerotic lesions (NCSL) are dental cervical lesions with noncarious sclerotic dentine (NCSD), which appears smooth, hard, and either light yellow or dark brown. Most NCSLs are wedge or dish shaped and commonly occur in canines and premolars, leading to dental hypersensitivity and aesthetic defect. The principal treatment is composite resin restoration; however, many clinical problems, such as retention loss, should not be ignored. NCSL's bonding interface includes NCSD and enamel, and interface pre-treatment can promote the bonding effect. This review summarizes current surface treatment methods and their influence on the bonding effectiveness of NCSL to provide guidance for clinical practice.

[Human mycobiome and diseases].

The proportion of mycobiome is less than 1% of human microbiome. However, fungal community plays a key role in human health and diseases. With high-throughput sequencing applications, the structure and composition of mycobiome in the mouth, lung, gut, vagina, and skin have been analyzed, and the role of microbiome in diseases has been investigated. Mycobiome also influences the composition of bacteriome and includes key species that maintain the structure and function of microbial communities. Fungi also influence host immune responses. In this review, we summarized the mycobiome com-position at various sites and different diseases and the interactions between fungi-bacteria and fungi-host.

[Inhibitive effect of extracts of Galla Chinesis on caries development in rats].

OBJECTIVE: To evaluate the inhibitive effect of Galla Chinesis extract (GCE) and GCE-B on dental caries formation and plaque microbiology in rats. METHODS: SPF-SD rats were infected with S. sobrinus to establish the caries rat model. The rats' teeth were treated with GCE and GCE-B topically twice a day for 5 weeks, or with NaF and CHX as positive controls, and deionized water as negative controls. The rats were then killed with CO2 asphyxiation. The dental caries of the rats were evaluated with Larson's modification of Keyes' system. RESULTS: The treatments with GCE and GCE-B significantly reduced the incidence of smooth-surface caries compared with the negative controls (43%-61% reduction, P < 0.05). No caries of Ds level was detected in the rats treated with NaF, GCE, or CHX. The treatment with GCE-B reduced the severity of smooth-surface caries compared with the negative controls, but with no statistical significance (P > 0.05). The incidence of sulcal caries were reduced significantly by all treatments (16%-41% reductions, P < 0.05) compared with the negative controls. The sulcal caries severity scores were significantly lower in the rats treated with NaF, GCE, CHX and GCE-B (Ds level: 21%-47% reductions, Dm level: 21%-65% reductions) than in the negative controls (P < 0.05). The reduction of Dx score by GCE-B (60% reduction) was significant (P < 0.05). No caries of Dx level was detected in the rats treated with NaF, GCE and CHX. CONCLUSION: GCE and GCE-B have anticaries effect in vivo, and GCE shows stronger effect than GCE-B.

[Recent advances in direct pulp capping materials].

The long-term effect of direct pulp capping and pulpotomy is closely related to the type of pulp capping materials. Various kinds of direct pulp capping materials are available, such as calcium hydroxide and mineral trioxide aggregates. Diverse new pulp capping materials have been reported recently. The excellent performance of calcium silicates has attracted much attention in previous studies. Moreover, enamel matrix derivative (Emdogain), which is capable of regeneration and remineralization, and other materials with similar capabilities have shown potential for use in pulp capping.

Quaternary ammonium silane-based antibacterial and anti-proteolytic cavity cleanser.

OBJECTIVE: Secondary caries and degradation of hybrid layers are two major challenges in achieving durable resin-dentin bonds. The objectives of the present study were to investigate the effects of a 2% quaternary ammonium silane (QAS) cavity cleanser on bacteria impregnated into dentin blocks and the gelatinolytic activity of the hybrid layers. METHODS: Microtensile bond strength was first performed to evaluate if the 2% QAS cavity cleanser adversely affected bond strength. For antibacterial testing, Streptococcus mutans and Actinomyces naeslundii were impregnated into dentin blocks, respectively, prior to the application of the cavity cleanser. Live/dead bacterial staining and colony-forming unit (CFU) counts were performed to evaluate their antibacterial effects. Gelatinolytic activity within the hybrid layers was directly examined using in-situ zymography. A double-fluorescence technique was used to examine interfacial permeability immediately after bonding. RESULTS: The cavity cleanser did not adversely affect the bond strength of the adhesives tested (p>0.05). Antibacterial testing indicated that 2% QAS significantly killed impregnated bacteria within the dentin blocks compared with control group (p<0.05), which was comparable with the antibacterial activity of 2% chlorhexidine (p>0.05). Hybrid layers pretreated with 2% QAS showed significant decrease in enzyme activity compared with control group. With the use of 2% QAS, relatively lower interfacial permeability was observed, compared with control group and 2% chlorhexidine (p<0.05). SIGNIFICANCE: The present study developed a 2% QAS cavity cleanser that possesses combined antimicrobial and anti-proteolytic activities to extend the longevity of resin-dentin bonds.

Optimizing resin-dentin bond stability using a bioactive adhesive with concomitant antibacterial properties and anti-proteolytic activities.

Secondary caries and hybrid layer degradation are two major challenges encountered in long-term resin-dentin bond stability. As a link between resin and dentin, adhesives that possess both antimicrobial and anti-proteolytic activities are in demand for eliminating bacteria-induced secondary caries and preventing hybrid layers from degradation. In the present study, a new quaternary ammonium methacryloxy silane (QAMS) prepared from sol-gel chemistry was incorporated into experimental adhesives to examine their antimicrobial effect and anti-proteolytic potential. This functional methacrylate resin monomer contains polymerizable methacryloxy functionalities as well as a positively-charged quaternary ammonium functionality with a long, lipophilic -C18H37 alkyl chain for puncturing the cell wall/membrane of surface-colonizing organisms. Antibacterial testing performed using agar diffusion test, live/dead bacterial staining and colony-forming unit counts all indicated that the QAMS-containing adhesives killed Streptococcus mutans and Actinomyces naeslundii in a dose-dependent manner via a predominant contact-killing mechanism. Gelatinolytic activity within the hybrid layers created by these adhesives was examined using in-situ zymography. Hybrid layers created with 0% QAMS-containing adhesive exhibited intense green fluorescence emitted by the hydrolyzed fluorescein-conjugated gelatin, with 4-fold increase in enzymatic activity compared with an experimental adhesive containing 5% QAMS. Taken together, incorporation of 5% QAMS in the experimental adhesive provides simultaneous antimicrobial and anti-proteolytic activities that are crucial for the maintenance of long-term resin-dentin bond integrity. STATEMENT OF SIGNIFICANCE: Durability of resin-dentin interfacial bond remains a clinically-significant challenge. Secondary caries caused by bacteria and the degradation of hybrid layers via endogenous dentin proteases are two important contributors to the poor resin-dentin bond durability. The present study developed a new 5% QAMS-containing adhesive that provides simultaneous antimicrobial and dentin protease inhibition functions to extend the longevity of resin-dentin bonds.

[Effects of the active compounds of M. officinalis on cariogenic bacteria].

OBJECTIVE: To investigate the effects of the principal biologically active compounds of M. officinalis on the growth and acid generation of the main cariogenic bacteria. METHODS: Streptococcus mutans, Streptococcus sanguis, Actinomyces naeslundii, Actinomyces viscosus, Lactobacillus rhamnosus were chosen as the experimental bacteria. The active compounds (Magnolol and Honokiol) were separated from M. officinalis and then the effects of the two agents on the growth and acid generation of the bacteria were assessed. The minimal inhibitory concentration (MIC) and the minimal biofilm eradication concentration (MBEC) of the test strains were determined by MBEC-Device. RESULTS: It was found that the growth of not only plantonic bacteria but also the biofilm were efficiently inhibited by Magnolol and Honokiol. The two agents could also inhibit the acid production of the test strains. CONCLUSION: M. officinalis may be an effective anti-caries agent, and further researches will be necessary to define its usefulness in this aspect.

[Dental caries in children with cleft lip and/or palate in China].

OBJECTIVE: To determine the prevalence of dental caries in children with cleft lip and Palate. METHODS: A cross-sectional study was undertaken in 380 children with cleft lip and Palate and 339 children without cleft. Dental caries were measured with decayed-missing-filed-teeth index (DMFT/dmft) and the decayed-missing-filed-surface index (DMFS/dmfs). A questionnaire survey about the socio-economic conditions and lifestyles of the children's families was undertaken in the parents of the children. RESULTS: (1) The children with cleft Palates had a higher prevalence of caries and greater DMFT(S) and dmft(s) scores than the children without cleft (P < 0.05), except for those of 3 to 5 years old. (2) For the children of 3 to 5 years old, those with cleft lip and palate had significantly more caries than those with only a cleft lip or a cleft lip and alveolus (P < 0.05). The children who had surgical repairs had lower dmft(s) than those who had not (P < 0.05). CONCLUSION: (2) Chinese children with oral cleft have more dental caries than the children without cleft. (2) Children with cleft lip and palate have higher levels of dental caries than those with cleft lip alone. The children who had surgical repairs have less dental caries.

[Effect of Galla Chinesis on the demineralization of dental root tissue in pH cycling model].

OBJECTIVE: To evaluate the anti-demineralization efficacy of Galla Chinesis in pH cycling model for elucidating the anti-root caries mechanism. METHOD: Anti-demineralization efficacy evaluation of the natural medicine in the pH-cycling models was used . Sound human root blocks were pH-cycled through the treatment solution, acidic buffer and neutral buffer. The cycling times for demineralization study were 12 times, 2 times per day. The acidic buffers were retained for calcium analysis by atomic adsorption spectroscopy. The sections of blocks were analysed after pH-cycling by CLSM. Treatments were 4 g x L(-1). Galla Chinesis, 1 g x L(-1) NaF solution and distilled water. RESULT: Galla Chinesis was found to inhibit the demineralization in the pH cycling model. Although the effect was not as good as fluoride, there was no significant difference between the two groups. CONCLUSION: These data suggest that Galla Chinesis could modulate the mineralisation behaviour of root tissue in a defined chemical circumstance. These findings support the proposition that Galla Chinesis may be a promising anticaries natural medicine in the future.

Effect of high energy X-ray irradiation on the nano-mechanical properties of human enamel and dentine.

Radiotherapy for malignancies in the head and neck can cause common complications that can result in tooth damage that are also known as radiation caries. The aim of this study was to examine damage to the surface topography and calculate changes in friction behavior and the nano-mechanical properties (elastic modulus, nanohardness and friction coefficient) of enamel and dentine from extracted human third molars caused by exposure to radiation. Enamel and dentine samples from 50 human third molars were randomly assigned to four test groups or a control group. The test groups were exposed to high energy X-rays at 2 Gy/day, 5 days/week for 5 days (10 Gy group), 15 days (30 Gy group), 25 days (50 Gy group), 35 days (70 Gy group); the control group was not exposed. The nanohardness, elastic modulus, and friction coefficient were analyzed using a Hysitron Triboindenter. The nano-mechanical properties of both enamel and dentine showed significant dose-response relationships. The nanohardness and elastic modulus were most variable between 30-50 Gy, while the friction coefficient was most variable between 0-10 Gy for dentine and 30-50 Gy for enamel. After exposure to X-rays, the fracture resistance of the teeth clearly decreased (rapidly increasing friction coefficient with increasing doses under the same load), and they were more fragile. These nano-mechanical changes in dental hard tissue may increase the susceptibility to caries. Radiotherapy caused nano-mechanical changes in dentine and enamel that were dose related. The key doses were 30-50 Gy and the key time points occurred during the 15th-25th days of treatment, which is when application of measures to prevent radiation caries should be considered.

Revival of nitrogen-containing bisphosphonate-induced inhibition of osteoclastogenesis and osteoclast function by water-soluble microfibrous borate glass.

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious skeletal complication associated with the long-term oral or intravenous use of nitrogen-containing bisphosphonates (N-BPs). Here, we investigated the effects of an ionic cocktail prepared from water-soluble microfibrous borate glass on neutralizing the inhibitory effects of two heterocyclic N-BPs, risedronate or zoledronic acid, on osteoclastogenesis, apoptosis of differentiated osteoclasts and osteoclast function. Cell growth and proliferation assays were first performed on RAW 264.7 cells to optimize the concentrations of the ionic cocktail and N-BPs to be used for static cell culture. The pre-osteoclasts were then stimulated with RANKL to differentiate into osteoclasts. The effects of the ionic cocktail and N-BPs on osteoclast differentiation, apoptosis and function were subsequently examined using 3 series of experiments conducted at the gene, protein, morphological and functional levels. After concentration optimization, the ionic cocktail was found to partially reverse N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclast resorptive activity. Ultrastructural examination of osteoclasts that had been exposed to either N-BP identified classical features of late apoptosis and secondary necrosis, while osteoclasts exposed simultaneously to the concentration-optimized ionic cocktail and N-BPs exhibited only signs of early apoptosis that were possibly reversible. Taken together, the results of the 4 series of experiments indicate that the ionic cocktail produced from dissolution of borate glass dressings has the potential to rescue the adverse effects of heterocyclic N-BPs on osteoclast differentiation and function. These results warrant further confirmation using dynamic cell culture and small animal BRONJ models. STATEMENT OF SIGNIFICANCE: Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) may result in bisphosphonate-related osteonecrosis of the jaw (BRONJ) due to the suppression of normal bone turnover. There is no effective treatment for such a complication to date. This work reported the use of an ionic cocktail derived from water-soluble microfibrous borate glass to revert heterocyclic N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclasts resorption in static cell culture condition. This ionic cocktail may have the potential to be further developed into a new adjunctive treatment for BRONJ.

Saliva in the diagnosis of diseases.

Saliva is secreted from the salivary glands and has multiple functions, including mouth cleaning and protection, antibacterial effects and digestion. With the rapid advancement in salivaomics, saliva is well recognized as a pool of biological markers. Saliva, as a non-invasive and safe source, could be a substitute for blood in the diagnosis and prognosis of diseases. This review summarizes the latest advancements in saliva-related studies and addresses the potential value of saliva in the early diagnosis of oral diseases, such as dental caries and periodontal disease, as well as cancer, diabetes and other systemic disorders. Saliva biomarkers range from changes in the biochemical indices of DNA, RNA and proteins to the diversification of microbiota structures. This study integrates data reported in the recent literature and discusses the clinical significance and prospects for the application of saliva in the early diagnosis of diseases, translational medicine and precision medicine.

Alanine racemase is essential for the growth and interspecies competitiveness of Streptococcus mutans.

D-alanine (D-Ala) is an essential amino acid that has a key role in bacterial cell wall synthesis. Alanine racemase (Alr) is a unique enzyme that interconverts L-alanine and D-alanine in most bacteria, making this enzyme a potential target for antimicrobial drug development. Streptococcus mutans is a major causative factor of dental caries. The factors involved in the survival, virulence and interspecies interactions of S. mutans could be exploited as potential targets for caries control. The current study aimed to investigate the physiological role of Alr in S. mutans. We constructed alr mutant strain of S. mutans and evaluated its phenotypic traits and interspecies competitiveness compared with the wild-type strain. We found that alr deletion was lethal to S. mutans. A minimal supplement of D-Ala (150 µg·mL-1) was required for the optimal growth of the alr mutant. The depletion of D-alanine in the growth medium resulted in cell wall perforation and cell lysis in the alr mutant strain. We also determined the compromised competitiveness of the alr mutant strain relative to the wild-type S. mutans against other oral streptococci (S. sanguinis or S. gordonii), demonstrated using either conditioned medium assays or dual-species fluorescent in situ hybridization analysis. Given the importance and necessity of alr to the growth and competitiveness of S. mutans, Alr may represent a promising target to modulate the cariogenicity of oral biofilms and to benefit the management of dental caries.

[An in vitro study on effect of Nidus vespae extract on the acid production of three strains of oral bacteria].

OBJECTIVE: To inquire into the effect of different of Nidus Vespae extract (NVE) on growth and acid production of Streptococcus mutans, Streptococcus sanguis and Actinomyces viscosus. METHODS: Streptococcus mutans ATCC 25175, Streptococcus sanguis ATCC 10556 and Actinomyces viscosus ATCC 19246 were chosen as the experimental bacteria. Four extracts of Nidus Vespae were prepared and then the effects of these Nidus Vespae extracts on the acid production were determined. RESULTS: All of Nidus Vespae extracts could inhibit the growth the of the three strains, and NVE1, NVE3, NVE4 could inhibit the acid production of the three strains, NVE2 could inhibit the acid production of Actinomyces viscosus. CONCLUSION: Four extracts of Nidus Vespae could inhibit the acid production of three bacteria strains.

[The effects of natural medicine on adherence of Streptococcus mutans to salivary acquired pellicle].

OBJECTIVE: To investigate the effects of 5 kinds of natural medicine such as Radix et Rhizoma Rhei on the adherence of Streptococcus mutans to salivary acquired pellicle, and to screen effective natural medicines for the prevention of caries. METHODS: The in vitro model of experimental pellicle was saliva-coated hydroxyapatites (S-HA). Streptococcus mutans and S-HA were treated with natural medicines respectively, and then the adherence of bacteria to S-HA was tested. RESULTS: Radix et Rhizoma Rhei, Semen Arecae and Rhizoma Liguistici Chuanxiong could decrease the attachment of Streptococcus mutans to S-HA, and Semen Arecae was the most effective one. Radix Angelicae Dahuricae had no remarkable effect, and Catechu inhibited the adherence only after the bacteria being under treatment. CONCLUSION: Radix et Rhizoma Rhei, Semen Arecae, Rhizoma Liquistici Chuanxiong and Catechu could effectively inhibit the adherence of Streptococcus mutans to salivary acquired pellicle, but the effect of Radix Angelicae Dahuricae on the adherence is un-noticeable.

[Effect of tea polyphenol on the demineralization and remineralization of enamel in vitro].

OBJECTIVE: To investigate the effect of tea polyphenol (TP) on the mineralization behaviour of enamel in two sterile, in vitro systems. METHODS: In the demineralization study, sound enamel sections were pH-cycled. Treatments were 2000 mg/L TP, 200 mg/L TP, 2000 mg/L TP + 100 mg/L fluoride, 100 mg/L fluoride, and deionized water. In the remineralization study, surface-softened enamel was used and pH-cycled as above. Test treatments were 2000 mg/L TP, 2000 mg/L TP + 250 mg/L fluoride, 250 mg/L fluoride, and deionized water. The acidic buffers were retained for calcium analysis. The enamel was analysed before and after pH-cycling by microhardness. RESULTS: In the demineralization study, the calcium depletion rates(CDR) were (0.43 +/- 0.05), (0.49 +/- 0.006), (0.21 +/- 0.02), (0.21 +/- 0.03) and (0.50 +/- 0.11) microgram/(mm2.h) respectively. The Knoop hardness values(KHV) percent reduction were 94.19 +/- 3.50, 96.62 +/- 0.63, 74.74 +/- 4.09, 77.79 +/- 3.11 and 97.32 +/- 4.03 respectively. There were no significant differences within either the TP-only groups or the fluoride groups, but the fluoride groups were significantly more efficacious than the TP-only groups (P < 0.05). In the remineralization study, the KHV percent increase were -11.96 +/- 10.1, -21.32 +/- 11.3, -49.52 +/- 24.6 and -4.24 +/- 8.51 respectively. Notably more remineralization was observed in the fluoride group. There were no significant differences between the other groups (P > 0.05). CONCLUSION: The data of this in vitro study suggest that TP has no effect on de/remineralization of enamel blocks and there is no synergetic action of TP and fluoride in a sterile system. This finding supports the proposition that tea polyphenols exert an anti-caries effect via an anti-microbial mode-of-action.