OBJECTIVETo evaluate the effect of dentin matrix metalloproteinase (MMP) on the degradation of root dentin collagen.

METHODSRoot dentin powder was demineralized with acetic acid (pH 4.0) at 4 degrees C for 14 d, then dialysed and centrifuged. Precipitation was divided into 7 groups, with 6 samples in each group, and each sample was 50.0 mg. One milliliter artificial saliva with a different reagent was added in each sample respectively. The reagents were 2 mmol/L APMA (MMP activator), 2 mmol/L EDTA, 100 mmol/L EDTA, 200 mmol/L EDTA, 0.2% and 0.02% chlorhexidine (MMP inhibitor), and the blank artificial saliva was taken as control. The amount of degraded collagen of each sample was determined with hydroxyproline assay kit. Scanning electron microscope was employed to observe the morphological and structural changes of root dentin which was demineralized or put into artificial saliva after being demineralized.

RESULTSThe mean amount of degraded collagen in APMA group was significantly higher than that in the blank group (P < 0.05). The mean amount of degraded collagen in 2 mmol/L, 100 mmol/L, 200 mmol/L EDTA, 0.02% and 0.2% chlorhexidine groups was dramatically lower than that of the APMA group and the blank (P < 0.01). SEM observation indicated that the structural integrity of the collagen network on root surface dentin still existed in root dentin surface after being demineralized alone, while collagenous fibril was destructed and the structural integrity on root dentin surface disappeared after being demineralized and treated by artificial saliva.

CONCLUSIONSMMP in root dentin can degrade root dentin collagen after being activated at low pH followed by neutralization. The results suggest that host MMP may play an important role in the process of dentin caries formation.

Collagen ; metabolism ; Dental Caries ; enzymology ; Dentin ; metabolism ; Humans ; In Vitro Techniques ; Matrix Metalloproteinases ; metabolism ; Tooth Root ; metabolism

Many studies has been conducted concerning prevention of unnecessary complications such as root resorption during orthodontic tooth movement under various mechanical forces. Nowadays, the cause of the root resorption is not thought to be confined only to mechanical forces. But the factor that affects bone metabolism are thought to be major one of the predisposing factors. The light microscope and scanning electron microscope were used to the effects of 60gm, and 100gm of tipping force on root resorption of cats, which were treated with Etidronate disodium. The results were as follows: 1. In the 60gm control group, hyalinization on the compression site of periodontal ligament appeared after first week and second week. In the 60gm experimental group, it appeared after first week with low frequency. In the 100gm control group it appeared with high frequency by first and second week while in 100gm experimental group, it appeared with low frequency. 2. In the 100gm control group, resorption of the cementum and the alveolar bone rapidly increased after second week. In the 60gm experimental group, resorption or formation of alveolar bone and cementum didn't appear all through the experimental period. 3. In the 100gm control group. formation of cementum and alveolar bone appeared after first week while in the 100gm experimental group, formation of cementum and alveolar bone appeared after second week and fourth week respectively. In the 60gm control group, formation of the cementum didn't appear all through the experimental period. 4. In the control group, the root resorption of 100gm group was higher than that of 60gm group after second week, while in experimental group, root resorption didn't appear regardless of the forces.
Animals ; Cats ; Causality ; Dental Cementum ; Etidronic Acid* ; Hyalin ; Metabolism ; Periodontal Ligament ; Root Resorption* ; Tooth Movement* ; Tooth*

Tooth root development involves intricate spatiotemporal cellular dynamics and molecular regulation. The initiation of Hertwig's epithelial root sheath (HERS) induces odontoblast differentiation and the subsequent radicular dentin deposition. Precisely controlled signaling pathways modulate the behaviors of HERS and the fates of dental mesenchymal stem cells (DMSCs). Disruptions in these pathways lead to defects in root development, such as shortened roots and furcation abnormalities. Advances in dental stem cells, biomaterials, and bioprinting show immense promise for bioengineered tooth root regeneration. However, replicating the developmental intricacies of odontogenesis has not been resolved in clinical treatment and remains a major challenge in this field. Ongoing research focusing on the mechanisms of root development, advanced biomaterials, and manufacturing techniques will enable next-generation biological root regeneration that restores the physiological structure and function of the tooth root. This review summarizes recent discoveries in the underlying mechanisms governing root ontogeny and discusses some recent key findings in developing of new biologically based dental therapies.
Female ; Humans ; Tooth Root/metabolism* ; Odontogenesis ; Epithelial Cells ; Cell Differentiation ; Biocompatible Materials/metabolism*

OBJECTIVEThe purpose of this study was to investigate the changes of basic fibroblast growth factor (bFGF) expressed in normal human dental pulp at different root development stages of permanent teeth.

METHODSBased on the teeth root development status, the pulp tissues were classified into three groups: root just starting development, being in development and apical closed. The pulps were immunohistochemically examined by use of bFGF antibody.

RESULTSStaining was strongly positive in immature permanent teeth, especially at the stage of root just starting development. Image analysis indicated that the gray values of positive reaction in three groups were statistically different (P < 0.001). For the first group, the gray value of the outer pulp was higher than that of the pulp core. For the second group, the pulp core has a higher gray value in the coronal pulp, while a lower value in root pulp compared to the outer pulp.

CONCLUSIONWith the development of root formation, the expression of bFGF in dental pulp shows different characteristics. bFGF may play a role in dental pulp development and maturation.

Dental Pulp ; metabolism ; Dentition, Permanent ; Fibroblast Growth Factor 2 ; metabolism ; Humans ; Odontogenesis ; Tooth Root ; growth & development ; metabolism

Epithelial-mesenchymal interactions (EMIs) are critical for tooth development. Molecular mechanisms mediating these interactions in root formation is not well understood. Laser capture microdissection (LCM) and subsequent microarray analyses enable large scale in situ molecular and cellular studies of root formation but to date have been hindered by technical challenges of gaining intact histological sections of non-decalcified mineralized teeth or jaws with well-preserved RNA. Here,we describe a new method to overcome this obstacle that permits LCM of dental epithelia,adjacent mesenchyme,odontoblasts and cementoblasts from mouse incisors and molars during root development. Using this method,we obtained RNA samples of high quality and successfully performed microarray analyses. Robust differences in gene expression,as well as genes not previously associated with root formation,were identified. Comparison of gene expression data from microarray with real-time reverse transcriptase polymerase chain reaction (RT-PCR) supported our findings. These genes include known markers of dental epithelia,mesenchyme,cementoblasts and odontoblasts,as well as novel genes such as those in the fibulin family. In conclusion,our new approach in tissue preparation enables LCM collection of intact cells with well-preserved RNA allowing subsequent gene expression analyses using microarray and RT-PCR to define key regulators of tooth root development.
Animals ; Dental Cementum ; cytology ; metabolism ; Epithelial-Mesenchymal Transition ; physiology ; Gene Expression Regulation, Developmental ; Laser Capture Microdissection ; Mice ; Mice, Inbred Strains ; Odontoblasts ; metabolism ; Oligonucleotide Array Sequence Analysis ; Reverse Transcriptase Polymerase Chain Reaction ; Tooth Germ ; metabolism ; Tooth Root ; growth & development

Cementum is critical for anchoring the insertion of periodontal ligament fibers to the tooth root. Several aspects of cementogenesis remain unclear, including differences between acellular cementum and cellular cementum, and between cementum and bone. Biomineralization is regulated by the ratio of inorganic phosphate (Pi) to mineral inhibitor pyrophosphate (PPi), where local Pi and PPi concentrations are controlled by phosphatases including tissue-nonspecific alkaline phosphatase (TNAP) and ectonucleotide pyrophosphatase/phosphodiesterase 1 (NPP1). The focus of this study was to define the roles of these phosphatases in cementogenesis. TNAP was associated with earliest cementoblasts near forming acellular and cellular cementum. With loss of TNAP in the Alpl null mouse, acellular cementum was inhibited, while cellular cementum production increased, albeit as hypomineralized cementoid. In contrast, NPP1 was detected in cementoblasts after acellular cementum formation, and at low levels around cellular cementum. Loss of NPP1 in the Enpp1 null mouse increased acellular cementum, with little effect on cellular cementum. Developmental patterns were recapitulated in a mouse model for acellular cementum regeneration, with early TNAP expression and later NPP1 expression. In vitro, cementoblasts expressed Alpl gene/protein early, whereas Enpp1 gene/protein expression was significantly induced only under mineralization conditions. These patterns were confirmed in human teeth, including widespread TNAP, and NPP1 restricted to cementoblasts lining acellular cementum. These studies suggest that early TNAP expression creates a low PPi environment promoting acellular cementum initiation, while later NPP1 expression increases PPi, restricting acellular cementum apposition. Alterations in PPi have little effect on cellular cementum formation, though matrix mineralization is affected.
Alkaline Phosphatase ; metabolism ; Animals ; Cell Line, Transformed ; Dental Cementum ; cytology ; metabolism ; physiology ; Gene Expression Profiling ; Humans ; Mice ; Models, Animal ; Phosphoric Diester Hydrolases ; metabolism ; Pyrophosphatases ; metabolism ; Tooth Root ; metabolism ; physiology ; X-Ray Microtomography

OBJECTIVETo evaluate the anti-demineralization efficacy of Galla Chinesis in pH cycling model for elucidating the anti-root caries mechanism.

METHODAnti-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.

RESULTGalla 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.

CONCLUSIONThese 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.

Animals ; Calcium ; metabolism ; Cuspid ; drug effects ; pathology ; Dental Caries ; prevention & control ; Humans ; Hydrogen-Ion Concentration ; Insecta ; chemistry ; Materia Medica ; isolation & purification ; pharmacology ; Microscopy, Confocal ; Sodium Fluoride ; pharmacology ; Tooth Demineralization ; metabolism ; pathology ; prevention & control ; Tooth Remineralization ; Tooth Root ; drug effects ; metabolism ; pathology