Solubility study of phytochemical cross-linking agents on dentin stiffness

Objectives

The effects of interactions between cross-linking proanthocyanidins (PA) in polar solvents and type-I collagen of demineralized dentin were investigated.

Methods

Three PA-rich extracts, two from grape seed (GSEP and GSES) and one from cocoa (COE), were dissolved (water, ethanol:water and acetone:water) and analyzed for their ability to increase the modulus of elasticity of demineralized dentin. Sound dentin beams (0.5 mm × 1.7 mm × 7 mm) were fully demineralized and divided into 12 groups according to the type of cross-linking agent and solvents used. Specimens were immersed in the respective solutions and tested at baseline, 10, 30, 60, 120 and 240 min.

Results

The elastic modulus (EM) of dentin was significantly increased by the PA treatment regardless of time (p < 0.05 for all times). The extracts showed different solubility in different solvents. GSEP showed the highest increase in EM when diluted in distilled water and acetone at all exposure times. Both GSEs showed superior results when diluted in distilled water and after 4 h of treatment, while COE produced strongest enhancement when dissolved in ethanol:water.

Conclusions

The results indicates that herbal extraction process and other pharmacognostic parameters have an important influence on extract solubility as well as constitution and, consequently, on the PA–dentin matrix interaction.     

Horizontal root fracture with displacement in the primary dentition

Root fractures in the primary dentition are uncommon and little information is available concerning adequate treatment and prognosis. The most recently published guidelines recommend more invasive approaches but also discuss the need for further studies. This article examines how a horizontal root fracture in the primary dentition of a 3-year-old girl was treated by reducing the coronal fragment, followed by semi-rigid containment for 21 days. Radiographs taken one year after the initial trauma confirmed the success of this alternative approach.     

Effect of bur type on microtensile bond strengths of self-etching systems to human dentin

PURPOSE: To compare the microtensile bond strength (microTBS) of five adhesives to human dentin prepared with 600-grit SiC abrasive paper (SiC), a diamond rotary instrument, or a carbide bur. The null hypothesis was that different cavity preparation instruments do not affect adhesion of resin adhesives. MATERIALS AND METHODS: Human molars (n = 45) were randomly divided into three groups according to surface treatment. Each group was bonded using a total-etch adhesive (Single Bond, 3M ESPE), one of three self-etching primer systems (Clearfil SE Bond or ABF, Kuraray; Imperva Fluorobond, Shofu), or a self-etching adhesive (One-Up Bond F, Tokuyama). A 4-mm composite crown was built over the bonded surface. Specimens were stored in water for 24 h at 37 degrees C. They were sectioned into 0.7-mm-thick slabs, trimmed to a cross-sectional area of 1 mm2, and loaded to failure at a crosshead speed of 1 mm/min using a tabletop tester (EZ-Test, Shimadzu). Microtensile bond strength data were analyzed using analysis of variance and Fisher's PLSD test. RESULTS: Surface preparation using a carbide bur generally yielded higher bond strengths than preparation using either a diamond rotary instrument or SiC abrasive paper. SE Bond had the highest mean microTBS of the five adhesives tested. CONCLUSION: Resin-dentin bond strengths can be affected by the type of instrument used to prepare the tooth. Specifically, higher bond strengths might be achieved by using carbide burs rather than diamond cutting instruments.     

Genetic studies of syndromes with severe periodontitis and palmoplantar hyperkeratosis

The Papillon-Lefevre and Haim Munk syndromes are characterized by the presence of both palmoplantar hyperkeratosis (PPK) and severe early onset periodontitis. It is the early onset periodontal disease component that distinguishes these from other more common forms of PPK. It has been proposed that the periodontal disease component may be a casual association in individuals with PPK. Genetic syndromes with palmoplantar keratosis and severe early onset periodontitis may be due to specific bacterial infections in individuals with PPK. Recently, keratin gene mutations have been identified in several conditions typified by palmoplantar keratosis. The present study sought to test the hypothesis that a keratin gene defect similar to those previously identified in other PPK conditions is responsible for the Haim Munk and the Papillon-Lefevre syndromes. We have performed genetic linkage studies to test for linkage between polymorphic DNA loci within 2 cytokeratin gene families and the disease phenotype in Haim Munk syndrome and Papillon-Lefevre syndrome. Families with individuals segregating for the Haim Munk syndrome and the Papillon-Lefevre syndrome were examined to determine disease status, and genotyped for microsatellite DNA markers closely linked to the acidic (type I) and the basic (type II) cytokeratin genes on chromosomes 12 and 17. Genotype data were evaluated for microsatellite allele homozygosity in affected individuals. Results of these preliminary genetic studies suggest that the gene defect in Haim Munk syndrome is not due to a gene defect in either the type I or the type II keratin gene clusters. These findings suggest that Haim Munk syndrome may be genetically distinct from other more common forms of PPK that have been linked to the cytokeratin gene families, and suggest that mutations in genes other than keratin genes are responsible. Additional family studies are needed to confirm these preliminary findings.     

Effects of diagnostic threshold and overlapped approximal surfaces on reported caries status

The aims of this study were to examine the influence upon reported caries status of: 1) employing different diagnostic thresholds and 2) using differing conventions for treating approximal surfaces which appeared overlapped on posterior bitewing radiographs. Caries prevalence data from a group of 211 Scottish schoolchildren aged 5-15 yr studied during a trial of elective temporary tooth separation in general dental practice in Scotland were used. In this "moderate" caries group, values for dmft/DMFT rose significantly (P less than 0.001) when the D1 diagnostic threshold (all grades of lesion accepted) was applied in comparison with the D3 threshold (only caries into dentine recognised); dmft increasing from 3.9 to 5.4 and DMFT increasing from 1.7 to 4.7. This demonstrated that an over-optimistic impression of overall caries levels may be given when only the D3 threshold is used uncritically. In this study the status of approximal surfaces which were overlapped on bitewing radiographs was assessed by direct clinical examination using the temporary elective tooth separation technique. The investigation showed that, for this juvenile population, most (81.8% mesial, 93.1% distal) overlapped approximal surfaces were sound. Significantly more mesial than distal surfaces were found to be overlapped.     

Commercial soft drinks: pH and in vitro dissolution of enamel

Most soft drinks are acidic in nature and exposure to these drinks may result in enamel erosion. This study sought to measure the pH of 20 commercial brands of soft drinks, the dissolution of enamel resulting from immersion in these drinks, and the influence of pH on enamel loss. Comparison of the erosive potential of cola versus non-cola drinks as well as regular sugared and diet versions of the same brands was undertaken. The pH was measured immediately after opening the soft drink can. Enamel slices obtained from freshly extracted teeth were immersed in the soft drinks and weighed at baseline and after 6, 24, and 48 hours of immersion. Non-cola drinks had significantly higher pH values than cola drinks but showed higher mean percent weight loss. By contrast, sugared versions of the cola and non-cola drinks showed significantly lower pH values and higher mean percent weight loss than their diet counterparts. The pH value of the soft drink did not have a significant influence on the mean percent weight loss (r = -0.28). Prolonged exposure to soft drinks can lead to significant enamel loss. Non-cola drinks are more erosive than cola drinks. Sugared versions of cola and non-cola drinks proved to be more erosive than their diet counterparts. The erosive potential of the soft drinks was not related to their pH value.