Erosion protection benefits of stabilized SnF2 dentifrice versus an arginine-sodium monofluorophosphate dentifrice: results from in vitro and in situ clinical studies

Objectives

The aim of these investigations was to assess the ability of two fluoride dentifrices to protect against the initiation and progression of dental erosion using a predictive in vitro erosion cycling model and a human in situ erosion prevention clinical trial for verification of effectiveness.

Materials and methods

A stabilized stannous fluoride (SnF₂) dentifrice (0.454 % SnF₂ + 0.077 % sodium fluoride [NaF]; total F = 1450 ppm F) [dentifrice A] and a sodium monofluorophosphate [SMFP]/arginine dentifrice (1.1 % SMFP + 1.5 % arginine; total F = 1450 ppm F) [dentifrice B] were tested in a 5-day in vitro erosion cycling model and a 10-day randomized, controlled, double-blind, two-treatment, four-period crossover in situ clinical trial. In each study, human enamel specimens were exposed to repetitive product treatments using a standardized dilution of test products followed by erosive acid challenges in a systematic fashion.

Results

Both studies demonstrated statistically significant differences between the two products, with dentifrice A providing significantly better enamel protection in each study. In vitro, dentifrice A provided a 75.8 % benefit over dentifrice B (p < 0.05, ANOVA), while after 10 days in the in situ model, dentifrice A provided 93.9 % greater protection versus dentifrice B (p < 0.0001, general linear mixed model).

Conclusion

These results support the superiority of stabilized SnF₂ dentifrices for protecting human teeth against the initiation and progression of dental erosion.

Clinical relevance

Stabilized SnF₂ dentifrices may provide more significant benefits to consumers than conventional fluoride dentifrices.

Clinical enamel surface changes following an intra-oral acidic challenge

OBJECTIVES

Investigation of early enamel erosion using replica impressions to compare changes in enamel surface topography in vivo prior to and over a 24 h period following acid challenge.

METHOD

A single treatment, blinded, enamel replica clinical study was undertaken in 20 healthy subjects. Replica tooth impressions were taken at baseline, following acid challenge and 2, 4, 7 and 24 h post challenge. Subjects consumed 500 ml of acidic soft drink over 30 min. Scanning electron microscopy of surface tomography was characterised with a descriptive 5 point scale by four judges. Duplicate impressions were taken to assess reproducibility.

RESULTS

18 subjects had scorable sequences. Descriptive analyses showed erosive changes following acid consumption and reparative changes in the subsequent 24 h period. Comparing baseline replica to the 24 h replica, there were no significant differences (p=0.26) in tooth surface characteristics. Comparing the replica taken immediately following acidic challenge with the subsequent replicas at 2, 4, 7 and 24 h, showed clear reduction of erosive effects on the enamel surface at 2 h (p=0.02) and a highly significant reduction at 4, 7 and 24 h (p<0.001).

CONCLUSION

This methodology demonstrated the ability to follow the progression and recovery of early erosive enamel lesions over 24 h being accurate and reproducible. This study suggests enamel repair commences within 2 h following a substantial acidic challenge and is completed 4-24 h later. After 24 h, the tooth surface appeared visibly indistinguishable from the original tooth surface, suggestive of a recovery process occurring.

CLINICAL SIGNIFICANCE

Healthy erosive lifestyles often culminate in tooth wear. The time taken for enamel remineralisation following acidic challenge is unknown however, this study suggests the repair process is relatively slow following a substantial acidic challenge, and at least 4-24 h should elapse prior to further acidic consumption to allow for recovery.

Scaffold-free microtissues: differences from monolayer cultures and their potential in bone tissue engineering

OBJECTIVES

Cell-based therapies for bone augmentation after tooth loss and for the treatment of periodontal defects improve healing defects. Usually, osteogenic cells or stem cells are cultivated in 2D primary cultures, before they are combined with scaffold materials, even though this means a loss of the endogenous 3D microenvironment for the cells. Moreover, the use of single-cell suspensions for the inoculation of scaffolds or for the direct application into an area of interest has the disadvantages of low initial cell numbers and susceptibility to unwanted cellular distribution, respectively.

MATERIALS AND METHODS

We addressed the question whether an alternative to monolayer cultures, namely 3D microtissues, has the potential to improve osteogenic tissue engineering and its clinical outcome.

RESULTS

By contrast, to monolayer cultures, osteogenic differentiation of 3D microtissues is enhanced by mimicking in vivo conditions. It seems that the osteogenic differentiation in microtissues is enhanced by strong integrin-extracellular matrix interaction and by stronger autocrine BMP2 signaling. Moreover, microtissues are less prone to wash out by body fluids and allow the precise administration of large cell numbers.

CONCLUSION

Microtissue cultures have closer characteristics with cells in vivo and their enhanced osteogenic differentiation makes scaffold-free microtissues a promising concept in osteogenic tissue engineering.

CLINICAL RELEVANCE

Microtissues are particularly suitable for tissue engineering because they improve seeding efficiency of biomaterials by increasing the cell load of a scaffold. This results in accelerated osteogenic tissue formation and could contribute to earlier implant stability in mandibular bone augmentation.

Scaffold-free microtissues: differences from monolayer cultures and their potential in bone tissue engineering

Objectives

The paper’s aim is to review dentin hypersensitivity (DHS), discussing pain mechanisms and aetiology.

Materials and methods

Literature was reviewed using search engines with MESH terms, DH pain mechanisms and aetiology (including abrasion, erosion and periodontal disease).

Results

The many hypotheses proposed for DHS attest to our lack of knowledge in understanding neurophysiologic mechanisms, the most widely accepted being the hydrodynamic theory. Dentin tubules must be patent from the oral environment to the pulp. Dentin exposure, usually at the cervical margin, is due to a variety of processes involving gingival recession or loss of enamel, predisposing factors being periodontal disease and treatment, limited alveolar bone, thin biotype, erosion and abrasion.

Conclusions

The current pain mechanism of DHS is thought to be the hydrodynamic theory. The initiation and progression of DHS are influenced by characteristics of the teeth and periodontium as well as the oral environment and external influences. Risk factors are numerous often acting synergistically and always influenced by individual susceptibility.

Clinical relevance

Whilst the pain mechanism of DHS is not well understood, clinicians need to be mindful of the aetiology and risk factors in order to manage patients’ pain and expectations and prevent further dentin exposure with subsequent sensitivity.

The outcome of definitive or salvage radiotherapy for locally advanced hepatocellular carcinoma: A retrospective cohort study of 822 patients from a single institution

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Background: With technological development and awareness of efficacy, radiotherapy (RT) is more frequently adopted in management of hepatocellular carcinoma (HCC). To assess the efficacy of RT, we conducted this retrospective cohort study from a single institute.

Methods: The analysis involved 822 patients who underwent definitive or salvage RT for locally advanced HCC from January 1997 to August 2009. Two-dimensional RT, 3-dimensional conformal RT (3D-CRT), and intensity-modulated RT including tomotherapy (IMRT) were carried out for 186 (22.6%), 579 (70.4%), and 57 (6.9%) patients, respectively. In a majority of patients, RT was done either concurrently with intra-arterial 5-FU (500 mg/m2) chemotherapy (CCRT group; 326 patients, 39.7%), or following transarterial chemoembolization (TACE+RT group; 244 patients, 29.7%). Total radiation dose was 30 to 64.8 Gy (median dose 45 Gy) in 1.8-2 Gy fraction.

Results: The median age of total 822 patients was 55 and 84.3% was male. The 2, 3, and 4-year overall survival rates of total patients were 21.2, 13.1, and 10.1%, respectively. In 2-year survival, the patients with Child-Pugh class A did better than B or C (23% vs 10.9%, p<0.001), without portal vein thrombosis (PVT) did better than with PVT (26.8% vs 14.3%, p<0.001), and without lymph node metastasis (LNM) did better than with LNM (22.9% vs 11.7%, p<0.001). Patients with total dose higher than 45 Gy did better than those with less than 45 Gy (30.1% vs. 15.6%, p<0.001). The best outcome was shown in patients received higher than 45 Gy using 3D-CRT or IMRT, with 2-year overall survival rates of 25.9% (CCRT) and 41.3% (TACE+RT).

Conclusions: This study showed a substantial effect of RT in locally advanced HCC. Further analysis will be continued to provide the best option of radiotherapy for locally advanced HCC.

No significant financial relationships to disclose.

Early experience of combination treatment of sorafenib and radiotherapy in patients with advanced hepatocellular carcinoma (HCC)

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Background: Although sorafenib has been recognized as a standard therapy for advanced HCC, its antitumor effect as a single modality seems unsatisfactory. In this study, we report our early experience of combination treatment of sorafenib and radiation in locally advanced or metastatic HCC.

Methods: From 2007 to 2009, a total of 22 HCC patients were treated with concurrent sorafenib (400 mg/day) and radiation. Nine patients received local radiotherapy 45-54 Gy in 1.8-5 Gy/fraction on the primary tumor with sorafenib (primary group). In the primary group, number of patients in stage III, IVA, and IVB was 1, 4, and 4, respectively. The remaining 13 patients received local radiotherapy 30-58.4 Gy in 1.8-6 Gy/fraction on the metastatic tumor with sorafenib (metastatic group). The metastatic sites involved bones (8 patients), lymph nodes (3 patients), chest wall (1 patient) and pelvic cavity (1 patient). Toxicity and tumor response were evaluated.

Results: In toxicity, the primary group presented hand-foot syndrome in 3 patients, grade 2 GI toxicity in 1 patient, and grade 2 thrombocytopenia in 1 patient. The metastatic group showed hand-foot syndrome in 2 patients and grade 1-2 GI toxicity in 4 patients. Grade 3 thrombocytopenia was observed in 2 patients, in whom the initial platelet count was less than 100,000/mm3. In tumor response, the primary group presented partial response and stable disease in 6 patients and 1 patient, respectively, among 8 assessable patients (PR rate; 6/8, 75%). Tumor marker AFP decreased from pretreatment 9,710±19,208 ng/mL to post- treatment 1,410±2,866 ng/mL. In the metastatic group, significant pain palliation was shown in 7 among 8 patients (87.5%) in Visual Analogue Scale. In the remaining 5 patients, tumor response was shown as partial response and stable disease in 4 patients and 1 patient, respectively (PR rate; 4/5, 80%).

Conclusions: In combination treatment of sorafenib and radiation, toxicity was acceptable. The substantial tumor response was also observed. Although this is the limited experience, the results of this study urge the initiation of a controlled clinical trial to verify the effect of combination treatment of sorafenib and radiotherapy.

No significant financial relationships to disclose.