Parental perceptions and acceptance of silver diamine fluoride staining

Background

The caries arrest that can be achieved by using silver diamine fluoride (SDF) offers a minimally invasive and inexpensive alternative to traditional restorative caries treatment. The authors evaluated how the dentinal staining that is associated with SDF influences the acceptance of this treatment among parents of young children in the New York City metropolitan area.

Clinical and SEM assessment of ART high-viscosity glass-ionomer sealants after 8–13 years in 4 teeth

Objectives

Resin composite sealants are retained longer than low-viscosity glass-ionomer sealants. Nevertheless, a systematic review showed that there is no evidence that resin composite sealants are superior to low-viscosity glass-ionomers in preventing dentine carious lesion development. This case study aimed to investigate reasons for this.

Methods

4 teeth were sealed with 2 brands of high-viscosity glass-ionomer according to the ART technique in 2 children aged 10 and 11.5 years, having a low caries-risk status, and followed clinically for between 8 and 13 years. At the final year, impressions were taken for SEM images that were assessed by two evaluators.

Results

Pits and fissures that were clinically diagnosed as free of sealant material appeared to contain remnants of high-viscosity glass-ionomer sealant material in the deeper parts of pits and fissures, on SEM images of 3 teeth.

Conclusion

This study confirms the likelihood that remnants of high-viscosity glass-ionomer sealant material are retained and block the deeper parts of pits and fissures even after the sealant appears to have disappeared clinically, exercising their carious lesion preventive effect.     

Microleakage and sealant penetration in contaminated carious fissures

Objectives

The aim of the present in vitro study was to evaluate the effect of an adhesive system on microleakage and sealant penetration depth in carious fissures after different surface contamination circumstances.

Methods

Extracted third molars (n = 128) with small occlusal cavitated carious lesions were randomly divided into eight experimental groups and sealed under four different surface conditions. 1, Dry conditions; 2, water contamination; 3, saliva contamination; 4, saliva contamination and air-drying. Two sealant protocols were applied, one using a fissure sealant (Teethmate F) and one using an additional adhesive system (SA primer and Photo Bond). The control group consisted of sound third molars (n = 16), that were sealed under dry conditions. After thermocycling (n = 500 cycles), teeth were immersed in 1% methylene blue for 24 h, sectioned and digitally photographed. Microleakage was evaluated on a three-point rating scale and analysed using a Chi-square test. Additionally, the presence of caries and incomplete sealant penetration was scored from photographs and analysed using logistic regression.

Results

A statistical significant difference regarding microleakage scores was present between sealed carious and sealed sound fissures. The use of an adhesive system in case of water contamination significantly reduced microleakage (p < 0.05). With regard to sealant penetration depth, there were significant differences present for carious sealed fissures, use of an adhesive system prior to sealing, and water and saliva contamination.

Conclusions

Use of an adhesive system improved the effectiveness of sealants placed after water contamination in carious fissures. However, sound fissures showed less microleakage and better penetration abilities than carious fissures.     

A New “Silver-Bullet” to treat caries in children – Nano Silver Fluoride: A randomised clinical trial

Background

Untreated dental caries in children remains a public health challenge in poor communities.

Objectives

This prospective controlled clinical trial investigated the effectiveness of a new anti-caries agent, Nano Silver Fluoride (NSF), applied once a year to arrest caries in children.

Methods

One hundred thirty decayed primary teeth were randomly divided into two groups: NSF as the experimental agent and water as the control group. Teeth were clinically diagnosed and treated by one masked examiner and followed up at seven days and five and 12 months by another calibrated examiner who was blinded to the type of treatment. The criteria of the ICDAS II were followed to determine the activity of lesion and the diagnosis of caries. The Pearson's chi-square test was used to compare the groups during different follow-up exams.

Results

At seven days, 81% of teeth in the NSF group exhibited arrested caries, whereas in controls, no teeth had arrested decay (p < 0.001) [PF, prevented fraction = 81%]. After five months, the NSF group had 72.7% with arrested decay, and the control group had 27.4% (p < 0.001) [PF = 62.5%]. At 12 months, 66.7% of the lesions treated with NSF were still arrested, while the control group had 34.7% remaining arrested (p = 0.003) [PF = 50%]. The number need to treat (NNT) at five months was two, and at 12 months, the number was three.Clinical Signi?cance: The NSF formulation is effective to arrest active dentine caries and not stain teeth.

Conclusions

NSF was demonstrated to be effective in arresting caries in children in poor communities.     

Effect of pit and fissure sealants on caries detection by a fluorescent camera system

Objective

The aim of this study was to evaluate the effect of sealant placement on the detection of caries by a fluorescent camera (FC), the Spectra caries detector.

Materials and methods

In a laboratory study, FC images and readings were obtained from 31 extracted teeth, before and following application of clear sealants (Shofu Clear or Delton unfilled), or opaque sealants (3M Clinpro or Delton FS). Teeth were then sectioned and examined for enamel or dentine caries. Using each tooth's true caries diagnosis, the sensitivity and specificity of the FC measurements in detecting dentine caries was calculated. In the clinical study, FC readings were obtained from 41 molars in children prior to and following application of clear sealants.

Results

Following application of Shofu or Delton unfilled there were reductions in the mean FC readings of 10% (p = 0.5) and 8.2% (p = 0.009), respectively. Application of two opaque sealants, 3M or Delton FS significantly reduced mean FC readings 16.2% and 20.8% (p < 0.5), respectively. Although the carious lesions could still be observed in FC images from teeth with opaque sealants there was a significant loss of sensitivity in detecting dentinal caries. Clear sealant application caused an insignificant loss of detection sensitivity. Following application of clear sealants to children's molars there was a small (4.01%) but significant (p < 0.01) reduction in FC readings recorded from these teeth.

Conclusions

The FC can detect caries under clear sealants with little loss of sensitivity. Although lesions can be seen through opaque sealants, loss of sensitivity precludes accurate lesion assessment.     

8-Year Follow-up of Central Giant Cell Lesion Mimicking Apical Periodontitis

Introduction

Lesions of nonendodontic origin may mimic apical periodontitis. Central giant cell lesions (CGCLs) are aggressive or nonaggressive benign idiopathic intraosseous lesions of the jaw. This report describes a case of a CGCL in the periapical region of teeth #21–#26 of a 17-year-old female who sought orthodontic care because of a change in the position of tooth #23.

Methods

Clinical examination revealed mild facial asymmetry caused by increased volume in the mental region and cortical bone expansion but no cortical disruption. A panoramic radiograph showed a well-defined radiolucent osteolytic lesion involving teeth #21–#26. The cortical bone was not affected, and there was no root resorption. Incisional biopsy was performed, and the diagnosis was a CGCL. The lesion was enucleated surgically. CGCLs should be included in the differential diagnosis of jaw lesions that mimic apical periodontitis.

Results

The patient subsequently underwent orthodontic treatment successfully.

Conclusions

The 8-year clinical and radiographic follow-up confirmed lesion remission, no recurrence, and pulp vitality of all teeth.     

Comparison of remineralization effect of three topical fluoride regimens on enamel initial carious lesions

Objectives

Some studies have been conducted to evaluate the effect of different topical fluoride regimens on the remineralization of initial carious lesions. This study was conducted to compare the effects of 3 topical fluoride treatments on the surface microhardness, fluoride uptake, and fluorescence lesion area in enamel.

Methods

Forty-eight bovine teeth were demineralized and subjected to one of the following treatments: (1) no treatment (control), (2) iontophoresis using 2% sodium fluoride solution, (3) 1.23% acidulated phosphate fluoride gel application, and (4) 5% sodium fluoride varnish application. Six persons continuously wore a mandibular removable appliance mounted with eight treated bovine teeth orally for 4 weeks, except while eating, sleeping, and brushing. Microhardness of enamel surfaces was measured using a digital microhardness tester. The fluoride concentration was analyzed using a fluoride electrode, and the fluorescence lesion area was calculated by confocal laser scanning microscopy.

Results

No significant differences in the microhardness were observed in response to the 3 fluoride regimens. The highest level of fluoride was observed in the APF gel group. APF gel group also showed significantly reduced fluorescence lesion areas compared to those of the control group.

Conclusions

The fluoride regimens showed no difference in surface microhardness; although APF gel showed the best effects in terms of fluoride uptake and decrease in the fluorescence lesion area, its effects were not significantly different from those of fluoride varnish.     

Conventional caries removal and sealed caries in permanent teeth: a microbiological evaluation

Objectives

The aim of this study was to compare microbiological infection after conventional carious dentine removal with incomplete carious dentine removal and sealing.

Methods

Eighty-seven patients (12–50 years of age) under treatment at the Dental Clinics of the Federal University of Rio Grande do Sul (UFRGS), Brazil, participated in the study. The patients presented 90 posterior permanent teeth with primary caries. The lesions were coronal, active, and reached at least the middle third of the dentine. None of the teeth exhibited spontaneous pain, sensitivity to percussion or apical pathology (detected through radiographic exams). Pulp sensibility was confirmed by the cold test. The lesions were divided into 2 experimental groups: complete caries removal (CCR) based on hardness criteria (n = 60 lesions) and incomplete caries removal (ICR) and sealing (n = 32 lesions). Microbiological samples were obtained from the initial demineralized dentine, after CCR and after ICR-Seal.

Results

The number of anaerobic and aerobic bacteria, lactobacilli, and mutans streptococci decreased at the end of treatment (p < 0.05). Significantly less anaerobic bacteria (p < 0.01), aerobic bacteria (p = 0.02), and mutans streptococci (p < 0.01) growth was observed after ICR-Seal compared to CCR. The difference in lactobacilli was insignificant (p = 0.08). The amount of bacteria detected after conventional caries removal was higher than that which remained in sealed caries lesions.

Conclusions

The results suggest it is not necessary to remove all carious dentine before the restoration is placed because over time, sealing of carious dentine results in lower levels of infection than traditional dentine caries removal.

Clinical significance

The results of this study indicate that sealed carious dentine was less infected than the remaining dentine left after conventional caries removal and sealing. Our results support treatment of deep carious lesions in one session with incomplete removal of carious dentine.     

Controlling caries in exposed root surfaces with silver diamine fluoride: A systematic review with meta-analysis

Background

In this systematic review, the authors aim to assess the effect of silver diamine fluoride (SDF) in preventing and arresting caries in exposed root surfaces of adults.

Multiple Radiopaque Mandibular Lesions in a Patient with Apert Syndrome

Introduction

Apert syndrome (acrocephalosyndactyly) is a rare congenital malformation characterized by craniosynostosis, craniofacial anomalies, and symmetric syndactyly of the hands and feet. Oral manifestations usually include bifid uvula, a Byzantine arch palate associated with lateral swellings of the palatine processes, severe maxillary dental crowding associated with teeth malposition, severe open bite, dental caries, and gingival and periodontal disorders. Florid osseous dysplasia is an asymptomatic lesion mostly encountered during casual dental radiographic examinations as multiple sclerotic masses in 2 or more quadrants, usually in tooth-bearing regions.

Methods

A 32-year-old woman diagnosed with Apert syndrome was seen in our department for a routine dental examination. Radiographic evaluation showed multiple radiopaque lesions in the mandible. All teeth with radiopaque lesions gave positive responses to vitality tests, and the patient did not report any symptoms. Based on the clinical and radiographic findings, the diagnosis of florid osseous dysplasia in a patient with Apert syndrome was made. Because there were no signs of an intraoral infectious process or endodontic needs, the patient was followed during revisions for Apert syndrome, and the only treatment provided was conservative management of the many carious lesions observed during the clinical examination.

Conclusions

To our knowledge, this is the first study reporting the occurrence of florid osseous dysplasia in a patient with Apert syndrome. Conservative management should be performed in asymptomatic cases. Although rare, our case report highlights the importance of florid osseous dysplasia as a condition that may mimic lesions with an endodontic origin in patients with Apert syndrome.     

The inhibition effect of non-protein thiols on dentinal matrix metalloproteinase activity and HEMA cytotoxicity

Objectives

Phosphoric acid (PA) etching used in etch-and-rinse adhesives is known to activate host-derived dentinal matrix-metalloproteinases (MMPs) and increase dentinal permeability. These two phenomena will result, respectively; in degradation of dentine-adhesive bond and leaching of some monomers especially 2-hydroxyethyl methacrylate (HEMA) into the pulp that would negatively affect the viability of pulpal cells. This study is the first to investigate the inhibitory effect of non-protein thiols (NPSH); namely reduced glutathione (GSH) and N-acetylcysteine (NAC) on dentinal MMPs and compare their effects on HEMA cytotoxicity.

Methods

Dentine powder was prepared from human teeth, demineralized with 1% PA and then treated with 2% GSH, 2% NAC or 2% chlorhexidine (CHX). Zymographic analysis of extracted proteins was performed. To evaluate the effect of GSH, NAC and CHX on HEMA cytotoxicity, solutions of these compounds were prepared with or without HEMA and rat pulpal cells were treated with the tested solutions for (6 and 24 h). Cells viability was measured by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cytotoxicity data were analysed by one-way ANOVA and Tukey post hoc tests (p < 0.05).

Results

The inhibitory effect of GSH and NAC on dentinal MMPs was confirmed. GSH showed similar effectiveness to NAC regarding HEMA cytotoxicity inhibition.

Conclusion

NPSH were effective to inhibit dentinal MMPs and HEMA cytotoxicity.

Clinical significance

The tested properties of NPSH provide promising clinical use of these agents which would enhance dentine-bond durability and decrease post-operative sensitivity.     

Revascularization with and without Platelet-rich Plasma in Nonvital,Immature, Anterior Teeth: A Pilot Clinical Study

Introduction

This study was conducted to evaluate and compare maturogenesis induced by revascularization with and without platelet-rich plasma (PRP).

Methods

Twenty patients with nonvital, immature anterior teeth were randomly categorized into 2 groups. Subsequent to chemomechanical preparation, revascularization with and without PRP carried on a collagen sponge was induced in groups 1 and 2, respectively. The cases were followed up clinically and radiographically at 6- and 12-month intervals.

Results

Clinically, all cases were asymptomatic with complete resolution of signs and symptoms. Radiographically, there was a marked difference in periapical healing, apical closure, and dentinal wall thickening in group 2 in comparison with group 1. However, root lengthening was comparable for both of the procedures.

Conclusions

Revascularization is a conservative and an effective method for inducing maturogenesis in nonvital, immature teeth. Supplementations with PRP can potentially improve the desired biological outcome of this regenerative technique.     

10-Year Follow-up of Calcifying Odontogenic Cyst in the Periapical Region of Vital Maxillary Central Incisor

Introduction

Radiographic images may lead to misinterpretations of lesions of endodontic and nonendodontic origin. This report describes a case of a 10-year follow-up of a calcifying odontogenic cyst (COC) in the periapical region of a vital maxillary central incisor in a 9-year-old boy.

Methods

The patient revealed a history of a swelling in the periapical area of tooth #9. The patient denied any dental trauma or history of pain. Clinical examination revealed no mobility, but there was discrete discomfort when horizontal pressure was applied. Pulp vitality was present in all maxillary anterior teeth. Radiographs revealed an oval radiolucent lesion in the periapical region of maxillary central incisor. The therapeutic option was enucleation of the periapical lesion and histologic examination of the specimen. Microscopic findings suggested the diagnosis of a COC.

Results

At a follow-up visit 10 years after surgery, panoramic and periapical radiographs showed new bone formation; the patient did not have any pain, and pulp vitality was maintained in all teeth in this area.

Conclusions

A COC should be part of the differential diagnosis of other jaw lesions, such as apical periodontitis. The definitive diagnosis of a COC can only be made after microscopic evaluation of the specimen. The follow-up is a helpful reference because it confirms the survival of pulp tissue and no recurrence of the COC.     

Histologic Study of a Human Immature Permanent Premolar with Chronic Apical Abscess after Revascularization/Revitalization

Introduction

Histologic studies of teeth from animal models of revascularization/revitalization are available; however, specimens from human studies are lacking. The nature of tissues formed in the canal of human revascularized/revitalized teeth was not well established.

Methods

An immature mandibular premolar with infected necrotic pulp and a chronic apical abscess was treated with revascularization/revitalization procedures. At both the 18-month and 2-year follow-up visits, radiographic examination showed complete resolution of the periapical lesion, narrowing of the root apex without root lengthening, and minimal thickening of the canal walls. The revascularized/revitalized tooth was removed because of orthodontic treatment and processed for histologic examination.

Results

The large canal space of revascularized/revitalized tooth was not empty and filled with fibrous connective tissue. The apical closure was caused by cementum deposition without dentin. Some cementum-like tissue was formed on the canal dentin walls. Inflammatory cells were observed in the coronal and middle third of revascularized/revitalized tissue.

Conclusions

In the present case, the tissue formed in the canal of a human revascularized/revitalized tooth was soft connective tissue similar to that in the periodontal ligament and cementum-like or bone-like hard tissue, which is comparable with the histology observed in the canals of teeth from animal models of revascularization/revitalization.     

Evaluation of active and arrested carious dentin using a pH-imaging microscope and an X-ray analytical microscope

A pH-imaging microscope was tested on carious teeth to examine the acid-base characteristics of active and arrested carious dentinal lesions and compared with an assessment of mineral loss in carious affected lesions using an x-ray analytical microscope. Extracted human molars, 22 active and 83 arrested carious teeth, were sliced vertically to maximize the presence of visible carious lesions. The pH change on the dentin surface was measured with a pH-imaging microscope, and the mineral loss was measured with an x-ray analytical microscope. The pH value of intact dentin and active and arrested carious dentinal lesions showed 7.0 (n=105), 5.8 (n=22) and 6.6 (n=83), respectively (analyzed by Kruskal-Wallis). The mineral loss was distinguishable in active dentinal lesions (4.92 times as much as intact dentin), while arrested lesions showed a slight mineral loss (2.19 times as much as intact dentin). The changes in pH value and mineral loss were significantly correlated (Pearson's correlation coefficients r=-0.8024) in active carious dentin lesions and weakly correlated (r=-0.1480) in arrested carious dentin lesions. Changes in tooth substance with the progression of the active carious process were reflected in a reduction in pH value and an increase in the amount of mineral loss.     

Nano-structural and compositional basis of devitalized tooth fragility

Objective

Increased tooth fragility after devitalization is commonly observed but there is no definite mechanistic explanation for such phenomenon. Therefore, it is important to analyze more profoundly structural and compositional properties of this altered form of dentin. The present study investigates the differences between normal and devitalized dentin using advanced techniques.

Methods

Atomic force microscopic imaging (AFM), energy dispersive X-ray analysis (EDX) and micro-Raman spectroscopy were performed on 16 dentin specimens, eight vital and eight that underwent root-canal treatment at least two years before extraction and had no infection in root canals before or after devitalization.

Results

The mean size of mineral crystals showed by AFM was larger in devitalized than in healthy dentin in the same age category. AFM phase shifts in devitalized cases revealed altered mechanical characteristics and suggested differences in composition of material between devitalized teeth and healthy controls. No significant difference in Ca/P ratio between vital and devitalized teeth was found using EDX. However, micro-Raman analyses showed that in devitalized teeth, apart from hydroxyapatite, dentin contained significant amounts of apatite phases with lower calcium content: octacalcium phosphate, dicalcium phosphate dihydrate and tricalcium phosphate.

Significance

Differences between vital and devitalized dentin bring new insights into the basis of devitalized tooth fragility. Larger mineral crystals could account for decreased mechanical strength in devitalized teeth. Moreover, calcium–phosphate phases with lower Ca content have lower material strength, and the presence of these phases in devitalized teeth may explain their increased fragility.     

Fracture resistance and cuspal deflection of incompletely excavated teeth

Objectives

Incomplete excavation reduces the risk of pulpal complications, but doubts remain regarding the mechanical properties of incompletely excavated teeth. Remaining carious dentine is suspected to not sufficiently support the restoration and to reduce bond strengths between the tooth and the restoration, with effects possibly varying depending on the depth of the remaining caries lesion. This study investigated fracture resistance (FR) and cuspal deflection (CD) of premolars after leaving or removing demineralized dentine in vitro.

Methods

In 48 premolars, shallow and deep artificial lesions (depths [mean ± SD] of 64 ± 18 μm and 771 ± 176 μm) were created on pulpo-axial walls of standardised mesial-distal-occlusal cavities. Demineralized dentine was either removed or left before adhesively restoring the tooth (n = 12/group). Restored teeth were submitted to thermo-mechanical cycling. CD was subsequently measured at loads of 200 N and 400 N, and teeth submitted to occlusal-perpendicular loading until fracturing occurred.

Results

FR was not significantly different between teeth with or without remaining demineralized dentine regardless of the lesion depth (p > 0.30, t-test). Irrespective of the removal technique, teeth with deep lesions showed significantly decreased FR (p ≤ 0.001). In contrast, CD was significantly increased in teeth with remaining demineralized dentine compared with completely excavated teeth (p ≤ 0.05; Mann–Whitney test).

Conclusions

Remaining demineralized dentine did not significantly decrease the fracture resistance of premolars in vitro. Effects of increased cuspal deflection on restoration margins should be assessed. This study showed no indication that incomplete excavation increases the risk of non-pulpal complications.

Clinical significance

Incomplete caries removal seems suitable to treat especially deep lesions. Leaving demineralized dentine does not seem to affect the fracture resistance of incompletely excavated teeth regardless of the lesion depth.     

Is hard tissue formation in the dental pulp after the death of the primary odontoblasts a regenerative or a reparative process?

Objectives

Conceptually, two types of tertiary dentine may be produced in response to caries and environmental irritations: “reactionary dentine” that is secreted by existing primary odontoblasts and “reparative dentine”, formed after the death of the odontoblasts by proliferation and differentiation of progenitor cells into odontoblast-like cells. Because histologic evidence for tubular dentine generated by newly differentiated odontoblast-like cells is lacking in human teeth, the present study examined pulpal cellular changes associated with caries/restorations, in the presence or absence of pulpal exposures.

Methods

Ninety-six extracted human teeth were histologically processed and serial sectioned for light microscopy: 65 contained untreated enamel/dentine caries; 20 were heavily restored and 11 had carious exposures managed by direct pulp-capping.

Results

Sparsely distributed, irregularly arranged dentinal tubules were identified from the tertiary dentine formed in teeth with unexposed medium/deep caries and in restored teeth; those tubules were continuous with the tubules of secondary dentine; in some cases, tubules were absent. The palisade odontoblast layer was reduced to a single layer of flattened cells. In direct pulp-capping of pulp exposures, the defects were repaired by the deposition of an amorphous dystrophic calcified tissue that resembled pulp stones more than dentine, sometimes entrapping pulpal remnants. This atubular hard tissue was lined by fibroblasts and collagen fibrils.

Conclusions

Histological evidence from the present study indicates that reparative dentinogenesis cannot be considered as a regenerative process since the so-formed hard tissue lacks tubular features characteristic of genuine dentine. Rather, this process represents a repair response that produces calcified scar tissues by pulpal fibroblasts.

Clinical significance

Formation of hard tissue in the dental pulp after the death of the primary odontoblasts has often been regarded by clinicians as regeneration of dentine. If the objective of the clinical procedures involved is to induce healing, reduce dentine hypersensitivity, or minimise future bacteria exposure, such procedures may be regarded as clinical success. However, current clinical treatment procedures are not adept at regenerating physiological dentne because the tissues formed in the dental pulp are more likely the result of repair responses via the formation of calcified scar tissues.     

Histologic Examinations of Teeth Treated with 2 Scaffolds: A Pilot Animal Investigation

Introduction

A growing body of evidence is building a case for the possibility of tissue regeneration within the root canal of necrotic teeth, allowing for continued root development. However, it remains unknown what type of tissue is produced after regenerative endodontics. The purpose of this study was to use blood clots and platelet-rich plasma (PRP) as scaffolds in regenerative endodontics under ideal conditions in a ferret model to examine the tissues generated within the root canals.

Methods

The pulps of 21 canine teeth from 7 young ferrets were extirpated using broaches without filing the canal walls. Bleeding was stimulated from the periapical tissues, and a blood clot was induced in the canal space to the level of the cementoenamel junction in 12 teeth. PRP was prepared and placed in the canals to the level of the cementoenamel junction in 9 teeth. The coronal access was sealed with mineral trioxide aggregate. Seven canines were not operated on and served as controls. Three months later, block sections including each canine and its surrounding tissues were removed for histologic evaluation. The tissues found in the canals of experimental teeth were compared with those in the control teeth.

Results

Almost all of the experimental teeth showed the presence of intracanal bonelike tissue. No evidence of dentinal wall thickening or apical narrowing was noted in the experimental teeth.

Conclusions

In this experimental model, the use of either PRP or blood clots during regenerative endodontics leads to the formation of intracanal bonelike tissue without continual root maturation.     

Does the Geometric Location of Odontoblast Differentiation and Dentinal Tubules Depend on a Reaction-Diffusion System between BMP2 and Noggin? A Mathematical Model

Introduction

The mesenchymal differentiation to odontoblasts is a complex process that determines the formation of dentinal tubules. This process involves a carefully regulated sequence of changes in the behavior of mesenchymal cells coordinated by the expression of different molecular factors that includes mainly the Noggin and bone morphogenetic protein type 2 (BMP2).

Methods

We investigated a bioregulatory mathematic model based on a set of equations of reaction-diffusion to predict the geometry of the formation of the dentinal tubules.

Results

We found that odontoblast location and the dentinal tubules formation are determined by the spatial distribution of a set of molecular signals that compete among themselves to maintain places of the greatest concentration of BMP2, which determines the step from mesenchymal cells to odontoblasts and the formation of the dentinal tubules.

Conclusions

This mathematic model suggests a regulatory loop between BMP2 and Noggin, which is highly stable and repeatable and determines the right location patterns of the odontoblasts and the formation of dentinal tubules. This mathematic approach allows us to understand biological phenomena and biochemical activity during the period of pulp differentiation.