The existing dentin bonding systems based on acid-etching technique lead to the loss of both extrafibrillar and intrafibrillar minerals from dentin collagen, causing excessive demineralization. Because resin monomers can not infiltrate the intrafibrillar spaces of demineralized collagen matrix, degradation of exposed collagen and resin hydrolysis subsequently occur within the hybrid layer, which seriously jeopardizing the longevity of resin-dentin bonding. Collagen extrafibrillar demineralization can effectively avoid the structural defects within the resin-dentin interface caused by acid-etching technique and improve the durability of resin-dentin bonding, by preserving intrafibrillar minerals and selectively demineralizing extrafibrillar dentin. The mechanism and research progress of collagen extrafibrillar demineralization in dentin bonding are reviewed in the paper.
Humans ; Collagen ; Dental Bonding ; Dentin/chemistry* ; Dentin-Bonding Agents/chemistry* ; Materials Testing ; Minerals ; Resin Cements/chemistry* ; Tooth Demineralization

Tooth decay is prevalent, and secondary caries causes restoration failures, both of which are related to demineralization. There is an urgent need to develop new therapeutic materials with remineralization functions. This article represents the first review on the cutting edge research of poly(amido amine) (PAMAM) in combination with nanoparticles of amorphous calcium phosphate (NACP). PAMAM was excellent nucleation template, and could absorb calcium (Ca) and phosphate (P) ions via its functional groups to activate remineralization. NACP composite and adhesive showed acid-neutralization and Ca and P ion release capabilities. PAMAM+NACP together showed synergistic effects and produced triple benefits: excellent nucleation templates, superior acid-neutralization, and ions release. Therefore, the PAMAM+NACP strategy possessed much greater remineralization capacity than using PAMAM or NACP alone. PAMAM+NACP achieved dentin remineralization even in an acidic solution without any initial Ca and P ions. Besides, the long-term remineralization capability of PAMAM+NACP was established. After prolonged fluid challenge, the immersed PAMAM with the recharged NACP still induced effective dentin mineral regeneration. Furthermore, the hardness of pre-demineralized dentin was increased back to that of healthy dentin, indicating a complete remineralization. Therefore, the novel PAMAM+NACP approach is promising to provide long-term therapeutic effects including tooth remineralization, hardness increase, and caries-inhibition capabilities.
Amines ; pharmacology ; Calcium ; Calcium Phosphates ; chemistry ; pharmacology ; Dentin ; chemistry ; Humans ; Nanocomposites ; chemistry ; Nanoparticles ; Tooth Remineralization ; methods

To explore the remineralization effect of bioactive glass NovaMin on demineralized dentin specimens, and to study the physical and chemical properties of formed structure at dentin surface.
 Methods: One mm-thickness coronal dentin slices were soaked in ethylene diamine tetraacetic acid (EDTA) for 48 h to prepare the completely demineralized dentin specimens and they were divided into 2 groups: an artificial saliva group (control group) and a NovaMin powder group. The specimens were treated with artificial saliva or NovaMin powder for 2 min (2 times every day), and the interval was 8 hours. Then, the specimens were soaked in the remineralization solution. After 7 days, the scanning electron microscope (SEM), energy dispersive X-ray (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) were used to detect dentin morphology, the physical and chemical properties of the formed structure at dentin surface.
 Results: The results of SEM showed that a defined surface layer in the NovaMin powder group could be observed in the SEM imaging at the 7th day, which completely occluded dentinal tubules; the EDX, ATR-FTIR and XRD analysis found that the mineralized layer formed at dentin surface was mainly composed of calcium and phosphate elements, which was similar to the hydroxyapatite-like crystal. However, there were no materials formed at the dentin surface in the control group, and the dentinal tubules were still open.
 Conclusion: NovaMin can remineralize the demineralized dentin specimens and occlude the dentinal tubules in hydroxyapatite-like crystal structure.
Dental Pulp Cavity ; Dentin ; chemistry ; Glass ; Microscopy, Electron, Scanning ; Saliva, Artificial ; Spectroscopy, Fourier Transform Infrared ; Tooth Remineralization ; methods

α-smooth muscle actin (α-SMA) and tenascin-C are stress-induced phenotypic features of myofibroblasts. The expression levels of these two proteins closely correlate with the extracellular mechanical microenvironment. We investigated how the expression of α-SMA and tenascin-C was altered in the periodontal ligament (PDL) under orthodontic loading to indirectly reveal the intrinsic mechanical microenvironment in the PDL. In this study, we demonstrated the synergistic effects of transforming growth factor-β1 (TGF-β1) and mechanical tensile or compressive stress on myofibroblast differentiation from human periodontal ligament cells (hPDLCs). The hPDLCs under higher tensile or compressive stress significantly increased their levels of α-SMA and tenascin-C compared with those under lower tensile or compressive stress. A similar trend was observed in the tension and compression areas of the PDL under continuous light or heavy orthodontic load in rats. During the time-course analysis of expression, we observed that an increase in α-SMA levels was matched by an increase in tenascin-C levels in the PDL under orthodontic load in vivo. The time-dependent variation of α-SMA and tenascin-C expression in the PDL may indicate the time-dependent variation of intrinsic stress under constant extrinsic loading.
Actins ; analysis ; drug effects ; Adult ; Animals ; Biomechanical Phenomena ; Cell Culture Techniques ; Cell Differentiation ; physiology ; Cells, Cultured ; Cellular Microenvironment ; physiology ; Humans ; Male ; Myofibroblasts ; physiology ; Orthodontic Wires ; Periodontal Ligament ; chemistry ; cytology ; Pressure ; Rats ; Rats, Sprague-Dawley ; Stress, Mechanical ; Tenascin ; analysis ; drug effects ; Time Factors ; Tooth Movement Techniques ; instrumentation ; Transforming Growth Factor beta1 ; pharmacology

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin (PA) for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin-dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.
Chlorhexidine ; chemistry ; pharmacology ; Collagenases ; pharmacology ; Dental Bonding ; Dental Cements ; chemistry ; Dental Stress Analysis ; instrumentation ; Dentin ; drug effects ; ultrastructure ; Dentin-Bonding Agents ; chemistry ; Gelatinases ; pharmacology ; Humans ; Hydroxyproline ; analysis ; Matrix Metalloproteinase 8 ; pharmacology ; Matrix Metalloproteinase Inhibitors ; chemistry ; pharmacology ; Proanthocyanidins ; chemistry ; pharmacology ; Stress, Mechanical ; Surface Properties ; Tensile Strength ; Tooth Demineralization ; pathology ; physiopathology

In this study, we evaluate the influence of post surface pre-treatments on the bond strength of four different cements to glass fiber posts. Eighty extracted human maxillary central incisors and canines were endodontically treated and standardized post spaces were prepared. Four post pre-treatments were tested: (i) no pre-treatment (NS, control), (ii) sandblasting (SA), (iii) silanization (SI) and (iv) sandblasting followed by silanization (SS). Per pre-treatment, four dual-cure resin cements were used for luting posts: DMG LUXACORE Smartmix Dual, Multilink Automix, RelyX Unicem and Panavia F2.0. All the specimens were subjected to micro push-out test. Two-way analysis of variance and Tukey post hoc tests were performed (α=0.05) to analyze the data. Bond strength was significantly affected by the type of resin cement, and bond strengths of RelyX Unicem and Panavia F2.0 to the fiber posts were significantly higher than the other cement groups. Sandblasting significantly increased the bond strength of DMG group to the fiber posts.
Aluminum Oxide ; chemistry ; Composite Resins ; chemistry ; Curing Lights, Dental ; classification ; Cuspid ; pathology ; Dental Bonding ; Dental Etching ; methods ; Dental Materials ; chemistry ; Dental Stress Analysis ; instrumentation ; Glass ; chemistry ; Humans ; Incisor ; pathology ; Materials Testing ; Microscopy, Electron, Scanning ; Polymerization ; Post and Core Technique ; instrumentation ; Resin Cements ; chemistry ; Root Canal Preparation ; methods ; Self-Curing of Dental Resins ; methods ; Silanes ; chemistry ; Stress, Mechanical ; Surface Properties ; Tooth, Nonvital ; therapy

We present the binding ability of a new peptide (CMPQVMPMC-) with dental enamel after being evaluated in the present study. Under a standard procedure, the recovery of M13 filamentous phage was greatly enhanced by displaying the peptide in phage coat protein p III. Then the cyclic peptide was synthesized using a solid method. The effect of the cyclic peptide in vitro biomineralization was tested in a single-diffusion microtiter plate gel system. Absorbance at 405 nm of each sample was recorded for 24 h at every 6 h intervals. The relatively increased values of each sample were expressed as percentages relative to the blank group (100%). The cyclic peptide resulted in a concentration-dependent delayed nucleation. In addition, the overall values of peptide groups at the end of 24 h were lower than those in the control group but much higher than those in the BSA control group.
Dental Enamel ; chemistry ; Peptides ; chemical synthesis ; chemistry ; Protein Binding ; Tooth Calcification

The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis; finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.
Crowns ; Dental Enamel ; pathology ; Dental Porcelain ; chemistry ; classification ; Humans ; Metal Ceramic Alloys ; chemistry ; Surface Properties ; Tooth Crown ; pathology ; Tooth Wear ; etiology

OBJEVTIVETo evaluate the effect of different restoration methods on fracture resistance of endodontically treated teeth.

METHODSFifty intact extracted maxillary first premolars were randomly divided into 5 groups. Medial-occlusal cavity models were established in all the test groups (B-E) according to the same standard, followed by treatments with defect exposure only, defect filling with light cured composite resin, indirect resin inlays, or light cured composite resin combined with Biosplint fiber. Each specimen was tested using a universal test machine at 1.00 mm/min until fracture and the fracture load was recorded. The load angle was 45 degree to the long axis of the teeth, and the load was pointed to the middle of the lingual surface on the buccal cusp. The fracture resistance was analyzed statistically.

RESULTSThe mean load to cause fracture of the samples in each group group A to E was 1.27∓0.41, 0.23∓0.17, 0.55∓0.31, 0.89∓0.40, and 0.98∓0.34 kN, respectively, showing significant differences between the groups.

CONCLUSIONThe fracture resistance of the teeth is reduced after endodontic therapy, but can be increased significantly by restoration with composite resin inlay or light cured composite resin combined with Biosplint fiber.

Bicuspid ; physiopathology ; Composite Resins ; chemistry ; Dental Materials ; chemistry ; Dental Restoration, Permanent ; methods ; Dental Stress Analysis ; Humans ; Inlays ; Maxilla ; Tooth Fractures ; physiopathology ; Tooth, Nonvital ; physiopathology ; therapy

OBJECTIVETo extracted DNA from ancient human teeth dated 3000 years ago unearthed in Xi'an and determine the genders for the individuals.

METHODSThirty five ancient human teeth were studied. A 'Reverse-root-canal' technique and a Chelex-100 solution were used to extract the DNA. Specific primers for Amelogenin gene were designed for PCR amplification.

RESULTSGenomic DNA was successfully extracted from 30 samples, for which 8 were determined to be males and 22 were females.

CONCLUSIONThe 'Reverse-root-canal' technique may be used for extracting DNA from ancient human teeth. Genetics method can supplement physical anthropology for determination of sex for ancient samples.

Amelogenin ; genetics ; China ; DNA ; analysis ; genetics ; isolation & purification ; Female ; History, Ancient ; Humans ; Male ; Paleodontology ; Polymerase Chain Reaction ; Sex Determination Analysis ; Tooth ; chemistry