Low-level laser therapy affects dentinogenesis and angiogenesis of in vitro 3D cultures of dentin-pulp complex.

To investigate the effects of gallium-aluminum-arsenide (GaAlAs) diode laser low-level laser therapy (LLLT) on angiogenesis and dentinogenesis of the dentin-pulp complex in a human tooth slice-based in vitro model. Forty tooth slices were prepared from 31 human third molars. Slices were cultured at 37 °C, 5% CO2, and 95% humidity and randomly assigned to one of the following groups: group I: no laser treatment, group II: 660-nm diode laser; energy density = 1 J/cm2, group III: 660-nm diode laser; energy density = 3 J/cm2, group IV: 810-nm diode laser; energy density = 1 J/cm2 and group V: 810-nm diode laser; energy density = 3 J/cm2. LLLT was applied on the third and fifth days of culture. After 7 days, tissues were retrieved for real-time RT-PCR analysis to investigate the expression of VEGF, VEGFR2, DSPP, DMP-1, and BSP in respect to controls. Lower energy density (1 J/cm2) with the 660 nm wavelength showed a statistically significant up-regulation of both angiogenic (VEGF: 15.3-folds and VEGFR2: 3.8-folds) and odontogenic genes (DSPP: 6.1-folds, DMP-1: 3-fold, and BSP: 6.7-folds). While the higher energy density (3 J/cm2) with the 810 nm wavelength resulted in statistically significant up-regulation of odontogenic genes (DSPP: 2.5-folds, DMP-1: 17.7-folds, and BSP: 7.1-folds), however, the angiogenic genes had variable results where VEGF was up-regulated while VEGFR2 was down-regulated. Low-level laser therapy could be a useful tool to promote angiogenesis and dentinogenesis of the dentin-pulp complex when parameters are optimized.

Effects of pulsing of light on the dentinogenesis of dental pulp stem cells in vitro.

Low power light (LPL) treatment has been widely used in various clinical trials, which has been known to reduce pain and inflammation and to promote wound healing. LPL was also shown to enhance differentiation of stem cells into specific lineages. However, most studies have used high power light in mW order, and there was lack of studies about the effects of very low power light in µW. In this study, we applied 810 nm LPL of 128 µW/cm2 energy density in vitro. Upon this value, continuous wave (CW) irradiation did not induce any significant changes for differentiation of human dental pulp stem cells (hDPSCs). However, the membrane hyperpolarization, alkaline phosphatase activity, and intracellular oxidative stress were largely enhanced in the pulsed wave (PW) with 30% of duty cycle and 300-3000 Hz frequencies-LPL in which LED driver work in the form of square wave. After 21 days of daily LPL treatment, Western blot revealed the dentinogenesis in this condition in vitro. This study demonstrates that the very low power light at 810 nm enhanced significant differentiation of hDPSCs in the PW mode and there were duty cycle dependency as well as pulsing frequency dependency in the efficiency.

[Optimization of reparative dentinogenesis in experimental osteoporosis]. / Optimizatsiia reparativnogo dentinogeneza pri éksperimental'nom osteoporoze.

The aim of the study was to assess histochemical changes of the dental pulp in direct pulp capping/experimental osteoporosis animal model. The study was performed on 20 two-year sheep with simulated acute pulpitis divided in 2 groups: main (15 animals/120 teeth) and control (5 animals/40 teeth). Direct pulp capping in the main group included tissue-engineered structure composed of a hydrogel PuraMatrix/3DM with ectomesenchymal stem cells immobilized on collagen sponge. In the control group collagen sponges with hydrocortisone furatsilin, chondroitin sulfate, аnaesthesinum were used for the same purpose. Dentinal bridge formation was much slower in controls than in the main group. Developed tissue-engineered design optimizes each stage of the healing process by protecting the pulp from infection, reduction of exudation, hemostatic effect and in long term contributes to a significant acceleration of the formation of the dentinal bridge.

Regenerative capacity of human dental pulp and apical papilla cells after treatment with a 3-antibiotic mixture.

INTRODUCTION: A 3-antibiotic combination (3Mix) has been widely used in regenerative endodontics. Recent studies recommend that a safe concentration of 3Mix is in the range of 0.39 µg/mL and 1 mg/mL because higher concentrations may limit tissue regeneration. The aim of this study was to determine the regenerative capacity of isolated human dental pulp cells (DPCs) and apical papilla cells (APCs) after a 7-day treatment with selected doses of 3Mix. METHODS: Primary human DPCs/APCs from the third passage were divided into control and experimental groups. In the control group, cells were cultured in regular complete media. In the experimental group, cells were cultured in complete media containing 0.39 µg/mL or 1 mg/mL of 3Mix for 7 days. After the treatment period, the media were changed, and the cells were further tested for proliferation and differentiation potential. For cell proliferation, a colorimetric qualification of 3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide was used on days 1, 3, 5, and 7. For differentiation potential, a dentinogenic differentiation medium was added into treated cells and cultured for 7, 14, and 21 days. Results were analyzed using quantitative alizarin red S staining and real-time reverse-transcription polymerase chain reaction. RESULTS: After 7 days of treatment, 100% cell death was discovered in the 1-mg/mL 3Mix group. The proliferative capacity of 0.39 µg/mL 3Mix-treated DPCs and APCs was significantly lower than that of untreated cells at all time points (P < .05). Mineralized nodule formation was found both in the 3Mix-treated and control groups, but it was significantly less in the 3Mix-treated groups at 7, 14, and 21 days (P < .01). Quantitative reverse-transcription polymerase chain reaction showed no statistically significant difference (95% confidence interval) in bone sialoprotein, alkaline phosphatase, and dentin matrix protein 1 gene expression in either 3Mix-treated DPCs or APCs compared with control groups. CONCLUSIONS: One milligram per milliliter of 3Mix had strong toxicity to DPCs/APCs when applied for 7 days, whereas 0.39 µg/mL 3Mix showed no toxicity but still affected cell proliferation and mineralization potential. However, no differences in dentinogenic gene expressions were observed between the 3Mix-treated and untreated groups.

Davallialactone reduces inflammation and repairs dentinogenesis on glucose oxidase-induced stress in dental pulp cells.

INTRODUCTION: The chronic nature of diabetes mellitus (DM) raises the risk of oral complication diseases. In general, DM causes oxidative stress to organs. This study aimed to evaluate the cellular change of dental pulp cells against glucose oxidative stress by glucose oxidase with a high glucose state. The purpose of this study was to test the antioxidant character of davallialactone and to reduce the pathogenesis of dental pulp cells against glucose oxidative stress. METHODS: The glucose oxidase with a high glucose concentration was tested for hydroxy peroxide (H2O2) production, cellular toxicity, reactive oxygen species (ROS) formation, induction of inflammatory molecules and disturbance of dentin mineralization in human dental pulp cells. The anti-oxidant effect of Davallilactone was investigated to restore dental pulp cells' vitality and dentin mineralization via reduction of H2O2 production, cellular toxicity, ROS formation and inflammatory molecules. RESULTS: The treatment of glucose oxidase with a high glucose concentration increased H2O2 production, cellular toxicity, and inflammatory molecules and disturbed dentin mineralization by reducing pulp cell activity. However, davallialactone reduced H2O2 production, cellular toxicity, ROS formation, inflammatory molecules, and dentin mineralization disturbances even with a long-term glucose oxidative stress state. CONCLUSIONS: The results of this study imply that the development of oral complications is related to the irreversible damage of dental pulp cells by DM-induced oxidative stress. Davallialactone, a natural antioxidant, may be useful to treat complicated oral disease, representing an improvement for pulp vital therapy.

Expression status of mRNA for sex hormone receptors in human dental pulp cells and the response to sex hormones in the cells.

OBJECTIVES: Sex hormone receptors are reported to be present in human dental pulp (HDP) cells. The purpose of this study was to examine the biological significance of oestrogen and androgen receptors (ER and AR, respectively) in HDP cells. DESIGN: We isolated HDP cells expressing ER- and AR-mRNAs and investigated the expression status of the receptors and the response to sex hormones in the cells. RESULTS: HDP cells expressing ER- and/or AR-mRNAs had the ability to form alizarin red S-positive nodules in which calcium and phosphorus were deposited in vitro and to differentiate into odontoblasts-like cells and dentine-like tissue in vivo. Individual clones isolated from HDP cells exhibited a different expression pattern of mRNA for ER and AR. Some clones expressed ERα- and/or ERß-mRNAs and the others coexpressed ER- and AR-mRNAs. Using the Ingenuity software, we found that 17ß-estradiol (E2) and dihydrotestosterone (DHT) could act directly on HDP cells through ER-or androgen signalling-mediated mechanisms. E2 or DHT stimulated the mRNA expression for genes related to odontogenesis of dentine-containing teeth and odontoblast differentiation, suggesting that ER and AR in HDP cells may be involved in dentinogenesis. CONCLUSIONS: Our findings provide new insights into the biological significance of sex hormone receptors in HDP cells.

In vitro guidance of dental pulp cells by Nd:YAG laser-irradiated endothelial cells.

OBJECTIVE: After endothelial cells were ablated by neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation, we investigated the response of pulp cells by examining the expression of transforming growth factor beta-1 (TGF-ß1). BACKGROUND DATA: The reaction of stimulated blood vessels is related to the initiation of dentinogenesis. After artificial injury of endothelial cells, pulp cells migrate to the site of the injured endothelial cells. MATERIALS AND METHODS: Rat aortic endothelial cells were cultured in the lower compartment of the experimental assembly, and a pulsed Nd:YAG laser was used to ablate these cells. Pulp cells were fluorescence labeled and cultured in the upper compartment. After 7-14 days of laser irradiation, total RNA was extracted from the cells in the lower chamber, and RT-PCR was performed to examine the expression of TGF-ß1 and osteocalcin mRNA. TGF-ß1 was also examined with immunohistochemistry. RESULTS: Seven days after laser irradiation, migrating pulp cells that expressed TGF-ß1 were observed in the lower compartment, and the expression of TGF-ß1 mRNA and osteocalcin mRNA was altered. Without laser irradiation, few migrating pulp cells were observed, and the expression of TGF-ß1 mRNA and osteocalcin mRNA was weak. These results suggested that TGF-ß1 mRNA expression is detected earlier in pulp cells rather than in endothelial cells following injury to endothelial cells. CONCLUSIONS: Using the Nd:YAG laser as an ablative stimulant, this study model was useful for investigating pulp-endothelial cell interactions in reparative dentinogenesis.

Dentin sialophosphoprotein and dentin matrix protein-1: Two highly phosphorylated proteins in mineralized tissues.

Dentin sialophosphoprotein (DSPP) and dentin matrix protein-1 (DMP-1) are highly phosphorylated proteins that belong to the family of small integrin-binding ligand N-linked glycoproteins (SIBLINGs), and are essential for proper development of hard tissues such as teeth and bones. In order to understand how they contribute to tissue organization, DSPP and DMP-1 have been analyzed for over a decade using both in vivo and in vitro techniques. Among the five SIBLINGs, the DSPP and DMP-1 genes are located next to each other and their gene and protein structures are most similar. In this review we examine the phenotypes of the genetically engineered mouse models of DSPP and DMP-1 and also introduce complementary in vitro studies into the molecular mechanisms underlying these phenotypes. DSPP affects the mineralization of dentin more profoundly than DMP-1. In contrast, DMP-1 significantly affects bone mineralization and importantly controls serum phosphate levels by regulating serum FGF-23 levels, whereas DSPP does not show any systemic effects. DMP-1 activates integrin signalling and is endocytosed into the cytoplasm whereupon it is translocated to the nucleus. In contrast, DSPP only activates integrin-dependent signalling. Thus it is now clear that both DSPP and DMP-1 contribute to hard tissue mineralization and the tissues affected by each are different presumably as a result of their different expression levels. In fact, in comparison with DMP-1, the functional analysis of cell signalling by DSPP remains relatively unexplored.

VDR deficiency affects alveolar bone and cementum apposition in mice.

OBJECTIVE: To compare the mineralisation density (MD), morphology and histology of alveolar bone and cementum amongst VDR +/+, VDR -/-, and VDR -/- groups supplemented with a diet TD 96348, containing 20% lactose, 2.0% calcium and 1.25% phosphorous. METHODS: Four groups of mice (6 mice/group) were identified by genotyping: VDR +/+ mice (VDR wild type), VDR -/- mice (VDR deficient), VDR -/- offsprings derived from VDR -/- parents receiving a supplemental diet (early rescued), and VDR -/- mice fed with a supplemental diet beginning at age one month (late rescued). All mice were sacrificed at age 70.5 days. Micro-CT was used to compare MD and morphology of alveolar bone and cementum. H-E and Toluidine blue staining was used to examine the ultrastructure of the alveolar bone and cementum at matched locations. RESULTS: In VDR -/- group, alveolar bone and cementum failed to mineralise normally. Early rescue increased MD of alveolar bone in VDR -/- mice with excessive alveolar bone formation, but which not observed in late rescue group. MD and morphology of cementum-dentine complex in both early and late rescue groups were comparable with VDR +/+ group when feeding with high-calcium rescue diet. CONCLUSIONS: VDR affects alveolar bone mineralisation and formation systemically and locally. However, cementum apposition and mineralisation is mainly regulated by calcium concentrations in serum.

Altered inorganic composition of dental enamel and dentin in primary teeth from girls with Turner syndrome.

In Turner syndrome (TS) one X-chromosome is missing or defective. The amelogenin gene, located on the X-chromosome, plays a key role during the formation of dental enamel. The aim of this study was to find support for the hypothesis that impaired expression of the X-chromosome influences mineral incorporation during amelogenesis and, indirectly, during dentinogenesis. Primary tooth enamel and dentin from girls with TS were analysed and compared with the enamel and dentin of primary teeth from healthy girls. Qualitative and quantitative changes in the composition of TS enamel were found, in addition to morphological differences. Higher frequencies of subsurface lesions and rod-free zones were seen in TS enamel using polarized light microscopy. Similarly, scanning electron microscopy showed that the enamel rods from TS teeth were of atypical sizes and directions. Using X-ray microanalysis, high levels of calcium and phosphorus, and low levels of carbon, were found in both TS enamel and dentin. Using microradiography, a lower degree of mineralization was found in TS enamel. Rule induction analysis was performed to identify characteristic element patterns for TS. Low values of carbon were the most critical attributes for the outcome TS. The conclusion was that impaired expression of the X-chromosome has an impact on dental hard tissue formation.

Involvement of the klotho protein in dentin formation and mineralization.

Klotho-deficient mice exhibit multiple pathological conditions resembling human aging. Our previous study showed alterations in the distribution of osteocytes and in the bone matrix synthesis in klotho-deficient mice. Although the bone and tooth share morphological features such as mineralization processes and components of the extracellular matrix, little information is available on how klotho deletion influences tooth formation. The present study aimed to elucidate the altered histology of incisors of klotho-deficient mice-comparing the findings with those from their wild-type littermates, by using immunohistochemistry for alkaline phosphatase (ALP), osteopontin, and dentin matrix protein-1 (DMP-1), terminal deoxynucleotidyl transferase-mediated deoxyuridinetriphosphate nick end-labeling (TUNEL) detection for apoptosis, and electron probe microanalyzer (EPMA) analysis on calcium (Ca), phosphate (P), and magnesium (Mg). Klotho-deficient incisors exhibited disturbed layers of odontoblasts, predentin, and dentin, resulting in an obscure dentin-predentinal border at the labial region. Several odontoblast-like cells without ALP activity were embedded in the labial dentin matrix, and immunopositivity for DMP-1 and osteopontin was discernible in the matrix surrounding these embedded odontoblast-like cells. TUNEL detection demonstrated an apoptotic reaction in the embedded odontoblast-like cells and pulpal cells in the klotho-deficient mice. EPMA revealed lower concentrations of Ca, P, and Mg in the klotho-deficient dentin, except for the dentin around abnormal odontoblast-like cells. These findings suggest the involvement of the klotho gene in dentinogenesis and its mineralization.

Effect of GaAIAs laser on reactional dentinogenesis induction in human teeth.

OBJECTIVE: This study investigated the biomodulatory effect of the gallium- aluminum-arsenate laser (GaAlAs) in pulp cells on reactional dentinogenesis, and on the expression of collagen type III (Col III), tenascin (TN), and fibronectin (FN) in irradiated dental tissues and controls (not irradiated). BACKGROUND DATA: Several studies suggest a biomodulatory influence of low-intensity laser radiation in the inflammatory and reparative processes of biological tissues. METHODS: Sixteen human premolar teeth were selected (after extraction due to orthodontal reasons) and divided into irradiated and control groups. Black class V cavity preparations were accomplished in both groups. For the irradiated group, GaAlAs laser (670 nm, 50 mW) with an energy density of 4 J/cm2 was used. Soon after, the cavities were restored with a glass ionomer and the extractions made after 14 and 42 days. RESULTS: Histological changes were observed by light microscopy; less intense inflammatory reaction in the irradiated group was found when compared to the controls. Only the irradiated group of 42 days exhibited an area associated with reactional dentinogenesis. After immunohistochemical analysis by the streptoavidin-biotin complex (SABC) method, the expression of Col III, TN, and FN was greater in the irradiated groups. CONCLUSION: Our results suggest that a GaAlAs laser with energy density of 4 J/cm2 and wavelength of 670 nm caused biomodulation in pulp cells and expression of collagen, but not collagen of the extracellular matrix, after preparation of a cavity.

Effects of protein deficiency induced by raw soy with and without sucrose on dentine formation and dentinal caries in young rats.

OBJECTIVES: The effects of protein deficiency and sucrose on formation and mineralization of dentine and dental caries in the molars of young rats were investigated. MATERIALS AND METHODS: Two groups of weaning Wistar rats received raw soy flour to induce protein deficiency with sucrose or starch as the carbohydrate source; the other two groups received skim milk powder as the protein source with sucrose or starch as the carbohydrate source. At the onset, tetracycline was injected to mark the dentine formed at that moment. After 6 weeks, lower molars were sectioned sagittally, and the areas of dentine formation and dentinal caries developed during the experiment were quantified separately in the first and second molars. Dental caries was also classified according to Schiff's reaction. Calcium (Ca), phosphorus (P) and total mineral elements were analyzed using an electron probe microanalyzer. RESULTS: Rats in both protein-deficient groups and normal protein sucrose group had significantly larger areas of dentine formed compared with rats fed with normal protein starch diet. Ca, P and total mineral elements in dentine were significantly reduced by normal protein sucrose diet. P content was significantly reduced in dentine of rats in protein-deficient sucrose group. Rats in normal protein sucrose group had significantly more and larger dentinal caries lesions than in any other group. CONCLUSION: This study suggests that protein deficiency induced by soy prevents the progression of dental caries even in highly cariogenic environment.

Factores de crecimiento aplicados a la operatoria dental: ¿un nuevo enfoque terapéutico? / Growth factors applied to operatirve dentistry: a new therapeutic approach?

A pesar del progreso logrado en el campo de la biología pulpar, la técnica y la filosofía sobre el recubrimiento pulpar ha generado inmensas controversias. Los clínicos conocen bien los éxitos logrados cuando se trabaja sobre el conducto radicular, pero no están muy convencidos de los éxitos de los recubrimientos pulpares durante actos de operatoria dental. Investigaciones recientes han demostrado que exposiciones pulpares pueden curar mediante la formación de dentina adicional y así separar la pulpa del medio externo. Es sabido, hoy en día, que el pronóstico de un recubrimiento pulpar es un tema a tratar en la operatoria dental. Los elementos que pueden producir un recubrimiento pulpar satisfactorio son discutivos en conjutno con los llamados factores de crecimiento. El propósito de crear nueva dentina es primariamente motivado por la necesidad clínica de restaurar este tejido mineralizado. La dentina rodea y protege el centro vital de la pieza dentaria que reside en la pulpa dental. Este tejido se encuentra mineralizado en un 80 por ciento y provee, en combinación con el esmalte, la mayor estructura del total de la masa dentaria. Al igual que el esmalte, la dentina es un tejido avascular pero, a diferencia de este, las células que sintetiza la dentina (los odontoblastos) pueden permanecer vitales a través de la vida adulta y volver a generar dentina adicional. Recientes investigaciones han sugerido que si los odontoblastos ubicados en la matriz preodontoblástica se pierden, es posible inducir la diferenciación de nuevas células odontoblásticas formadoras del complejo dentinopulpar utilizando las denominadas proteínas morfogenéticas. Desarrollos satisfactorios de procesos de ingeniería molecular que puedan regenerar dentina pueden tener aplicaciones clínicas como un agente para recubrimiento pulpar potenciado como desensibilizante, debido al sellado de los túbulos dentinarios

Factores de crecimiento aplicados a la operatoria dental: ¿un nuevo enfoque terapéutico? / Growth factors applied to operatirve dentistry: a new therapeutic approach?

A pesar del progreso logrado en el campo de la biología pulpar, la técnica y la filosofía sobre el recubrimiento pulpar ha generado inmensas controversias. Los clínicos conocen bien los éxitos logrados cuando se trabaja sobre el conducto radicular, pero no están muy convencidos de los éxitos de los recubrimientos pulpares durante actos de operatoria dental. Investigaciones recientes han demostrado que exposiciones pulpares pueden curar mediante la formación de dentina adicional y así separar la pulpa del medio externo. Es sabido, hoy en día, que el pronóstico de un recubrimiento pulpar es un tema a tratar en la operatoria dental. Los elementos que pueden producir un recubrimiento pulpar satisfactorio son discutivos en conjutno con los llamados factores de crecimiento. El propósito de crear nueva dentina es primariamente motivado por la necesidad clínica de restaurar este tejido mineralizado. La dentina rodea y protege el centro vital de la pieza dentaria que reside en la pulpa dental. Este tejido se encuentra mineralizado en un 80 por ciento y provee, en combinación con el esmalte, la mayor estructura del total de la masa dentaria. Al igual que el esmalte, la dentina es un tejido avascular pero, a diferencia de este, las células que sintetiza la dentina (los odontoblastos) pueden permanecer vitales a través de la vida adulta y volver a generar dentina adicional. Recientes investigaciones han sugerido que si los odontoblastos ubicados en la matriz preodontoblástica se pierden, es posible inducir la diferenciación de nuevas células odontoblásticas formadoras del complejo dentinopulpar utilizando las denominadas proteínas morfogenéticas. Desarrollos satisfactorios de procesos de ingeniería molecular que puedan regenerar dentina pueden tener aplicaciones clínicas como un agente para recubrimiento pulpar potenciado como desensibilizante, debido al sellado de los túbulos dentinarios (AU)

The effect of a high-sucrose diet on dentin formation and dental caries in hyperinsulinemic rats.

A high-sucrose diet decreases dentin formation and its minerals, but the mechanisms behind the effect are largely unknown. We studied the combined and separate effects of sucrose and insulin on dentin formation and mineral metabolism in growing rats. At weaning, animals were randomized into 4 groups: control/sucrose diets both with and without external insulin (1 U/x 100 g body weight daily). After 4 weeks, we measured areas of dentin formation, numbers and areas of dentinal caries lesions, and serum and urine glucose, insulin, Ca, Na, K, and P. Exogenous insulin increased serum and urine insulin levels and decreased serum glucose level, but did not affect dentin formation or dentinal caries lesion formation or progression. A high-sucrose diet decreased dentin formation independently of insulin. The differences in serum and urine minerals between the groups were minor. The findings confirm that sucrose-diet-induced reduction in dentinogenesis is independent of insulin and loss of minerals in urine.

A novel rat dentin mRNA coding only for dentin sialoprotein.

Dentin sialoprotein (DSP) is a major glycoprotein present in the mineralized dentin matrix that is expressed mainly by young and mature odontoblasts. Mutations in the DSP coding regions are linked to Dentinogenesis imperfecta I and II. indicating the importance of DSP in tooth formation. Previous studies have identified multiple mRNA transcripts in dentin that code for both DSP and phosphophoryns (PPs). Using reverse transcriptase-polymerase chain reaction (RT-PCR) to characterize these mRNA transcripts, we have identified a cDNA that codes for DSP, but not PP. This cDNA codes for a protein with 324 amino acids, 303 amino acids being identical to the published rat DSP sequence. However, the subsequent 21 amino acids are unique to this cDNA. Based on the coding sequence, the core protein is predicted to have a pI=4.24, a net charge of -34, and to contain four potential N-glycosylation sites and six potential sites for phosphorylation by casein kinase. That the corresponding mRNA was present in day 5 molar tooth germs was confirmed using RNA protection assays. These data, therefore, identify a novel transcript in rat tooth germs that codes only for DSP (designated as DSPII).

The effect of prostaglandin E2 and arachidonic acid on dentinogenesis in pigs.

The rate of dentinogenesis for the pig is quantified and the effects of dietary arachidonic acid supplementation and/or exogenous prostaglandin on dentine formation are defined. Thirty-six pigs were randomised to four groups, receiving either standard or supplemented formula and either prostaglandin E2 or placebo injections for fifteen days. Double tetracycline banding is used to measure rate of growth in the teeth. The average rate of dentinogenesis for all the study animals is 17.96 microm/day. Results show that the rate of dentinogenesis is not significantly affected by the interaction of hormone and dietary supplementation.

Effects of a high sucrose diet and intragastric sucrose feeding on the dentinogenesis, dental caries, and mineral excretion of the young rat.

Previous studies show that a high sucrose diet reduces the rate of primary dentinogenesis and increases dental caries, although their cause-effect relationship is still obscure. The purpose of this study was to explore whether the effect of sucrose load on the dentinogenesis and dental caries of young rat molars is mediated by systemic (intragastric) or by systemic and local (dietary) factors. At weaning (19 days), animals were randomized into the control, intragastric sucrose, and dietary sucrose groups for 4 weeks. The areas of dentin appositions and dentinal caries lesions were measured planimetrically. Caries was also determined with Shiffs staining and the width of predentin by histology. Urinary Ca, K, and Na levels were measured by flame photometry, urinary P levels using an UV method, and serum insulin levels using radioimmunoassay. Systemic and local sucrose load reduced dentin appositions and intragastric sucrose increased urinary Ca excretion. No differences in the width of predentin were noticed. Only dietary sucrose enhanced the occurrence and progression of caries. The present findings show that sucrose load reduces dentinogenesis by impairing the synthesis of dentin matrix, but also point out the crucial importance of the local sucrose challenge in the initiation of dental caries.

The effect of sucrose diet of rat dams on the dentine apposition and dental caries of their pups.

The purpose was to examine whether a sucrose diet in rat dams reduces dentine apposition and enhances dental caries in their pups. Sprague-Dawley rat pups were randomized into four groups on the day of birth. During the lactation period three dams received a standard rodent diet and three a diet containing 41% sucrose. At the age of 3 weeks the pups were weaned and given an intraperitoneal injection of oxytetracycline hydrochloride. During the experimental period, half of the pups of control dams received a sucrose diet (Cnt-Suc pups) and half of the pups of sucrose dams received a standard diet (Suc-Cnt pups). The pups in the other halves received the same diet as given to their dams during lactation (Cnt-Cnt and Suc-Suc pups). Urine samples were collected from dams and pups during the test periods. After 4 weeks the pups were killed, their blood was collected and their jaws sectioned sagittally. Dentine apposition was determined planimetrically and dental caries using Schiffs staining. Ca, K and Na of serum and urine were measured flame photometrically and P using an ultraviolet method. The lactational sucrose diet was associated with decreased P and Na excretion in the dams, and also with reduced dentine apposition in their pups. Reduced dentine apposition and induced Ca excretion with decreased P, K and Na excretions were observed in Suc-Suc pups and Cnt-Suc pups during the experiment period. Fewer intact teeth with more enamel and dentinal caries lesions occurred in sucrose-exposed groups (Suc-Cnt, Cnt-Suc and Suc-Suc pups). It was concluded that the sucrose diet given to dams during lactation changed the function of the pulp dentine complex of their pups leading to reduced dentinogenesis, but also predisposed to a reduction of dentinogenesis in pups during the experimental period and enhanced the occurrence of dental caries.