Rat Tooth Research Articles

PEG Push versus Pull Technique: Patient Safety at Stake

There are 2 commonly used techniques for Peroral Endoscopic Gastrostomy (PEG) placement, the push technique and the pull technique. We report a case of equipment malfunction using the push method (Sachs-Vine). A 50 year old female with a history of metastatic endocervical adenocarcinoma was admitted for small bowel obstruction. She was also found to have new abdominal wall and omental lesions on CT. PEG tube placement was scheduled for decompression. After the endoscopic evaluation, the location of the incision was identified by transillumination as well as finger indentation and ballottement. Through sterile methods, a scout needle was used to define the tract. A trocar was introduced through the gastric wall. A guide string was then introduced and snared. The endoscope was removed with the wire in place. Gastrostomy tube was fed over the wire until the tip reached the abdominal wall. As the tubing was being pulled through and the dilator reached the level of the abdominal wall, it broke causing the bumper end to become lodged in the back of the oropharynx. This caused airway compromise and transient desaturation down to 60%. The broken tubing was located and removed with rat tooth forceps and a new PEG placed successfully using the Pull method (Ponsky). There are multiple percutaneous techniques used for PEG tube placement including the Pull method, Push method, introducer (Russell) method, and the Versa which uses T-fasteners. With the pull method, the tube is tapered at the end with a loop that is connected and it is pulled down and out through the abdominal wall with the wire. With the Push method, the tube is fed over the wire, this requires the tube to be much longer and is made of two pieces connected together with a small dilator. Both the Push and Pull method are used regularly with no significant difference in complications reported. Although this may be a rare complication, considering the already deteriorated state of many patients getting PEG tube placement and the possible deadly consequences of this complication, choosing the Pull method over the Push method is something to be considered especially in patients with abdominal wall abnormalities.

Teneurin-2 presence in rat and human odontoblasts.

Teneurins are transmembrane proteins consisting of four paralogues (Ten-1-4), notably expressed in the central nervous system during development. All teneurins contain a bioactive peptide in their carboxyl terminal named teneurin C-terminal associated peptide (TCAP). The present study analyzed the detailed distribution of teneurin-2-like immunoreactive (Ten-2-LI) cells in developing and mature rat molar teeth, as well as in mature human dental pulps. Ten-2 and TCAP-2 genic expressions were also evaluated in rat and human dental pulps. Finally, Ten-2-LI cells were analyzed during the repair process after dentin-pulp complex injury in rat lower molar teeth. For this, histological sections of rat molar teeth and human dental pulps were submitted to immunohistochemical techniques, while total RNA from developing rat teeth and mature human dental pulps were submitted to conventional RT-PCR. Ten-2-LI cells were evident in the initial bell stage of rat molar teeth development, especially in ectomesenchymal cells of the dental papilla. Ten-2-LI odontoblasts showed strong immunoreactivity in rat and human mature teeth. Ten-2 and TCAP-2 genic expressions were confirmed in rat and human dental pulps. Dentin-pulp complex injury resulted in a decrease of Ten-2-LI odontoblasts after traumatic injury. Interestingly, Ten-2-LI cells were also evident in the pulp cell-rich zone in all postoperative days. In conclusion, Ten-2-LI presence in rat and human odontoblasts was demonstrated for the first time and Ten-2/TCAP-2 genic expressions were confirmed in rat and human dental pulps. Furthermore, it was revealed that Ten-2-LI rat odontoblasts can be modulated during the regenerative process.

COMPROMISED SOCKET HEALING IN RATS UNDER ZOLEDRONIC ACID TREATMENT AFTER EXTRACTION OF TEETH WITH PERIODONTITIS: INSIGHTS INTO THE PATHOGENESIS OF OSTEONECROSIS OF THE JAWS

Osteonecrosis of the jaws (ONJ) is a rare but severe complication of antiresorptive medications, such as bisphosphonates. To gain insight into the role of tooth extraction and dental disease in ONJ pathogenesis, this study investigated socket healing after extraction of healthy or periodontally compromised teeth in rats treated with zoledronic acid (ZA).

The effect of anchovy substrate application to fluor retention rate on Sprague Dawley rat tooth email (in vivo)

Usage of anchovies (Stolephorus insularis), which contain a high fluoride concentration in a CaF2 compound, needs to be examined as a topical fluoridative agent. Aim: To study the effects of an anchovy substrate application, either by chewing or smearing, in increasing fluoride retention of enamel. Fourteen Sprague Dawley rats were divided into five groups: baseline, experimental (feeding and smearing), and negative controls. After 15 days, lower incisor teeth were extracted and fluoride retention on the enamel surface was measured using EDX. Data were analyzed by the independent samples t-test, the Mann–Whitney U test, and the Kruskal–Wallis test. There was a significant increase in fluoride retention on enamel from the experimental groups compared to the negative control group (p < 0.05). Fluoride retention levels of the experimental feeding group (6.823%) were slightly higher than those of the experimental smearing group (6.783%), though the difference was not statistically significant (p < 0.05). Anchovy substrate application, either by chewing or smearing, increases fluoride retention on tooth enamel.

The effects of an anchovy (stolephorus insularis) substrate application on the level of fluor intrusion on Sprague Dawley rat teeth (in vivo)

Fluoride intrusion is one of the efficacy parameters of fluoridation. Anchovy (Stolephorus insularis), which contains a high fluoride concentration in the CaF2compound, can be used as a fluoridative agent which is affordable and easily obtained. The aim of this study is to prove the effectiveness of the application of an anchovy substrate (Stolephorus insularis), either by a feeding method or a topical method, for tooth fluoridation based on the depth of fluoride intrusion on the enamel. An in vivo experimental laboratory method was used. The subjects were 14 Sprague Dawley rats divided into five groups. The groups included a baseline control, a feeding negative control, a topical negative control, an anchovy feeding method, and a topical solution anchovy method. After 15 days of treatment, the teeth were cut transversely with a 0.5 mm thickness then processed to test for fluoride intrusion using fluorescence microscopy. There was increased fluor intrusion on the enamel of the experimental groups compared to the negative control groups (p<0.05).Fluoride intrusion using the topical fluoride method is higher than with the feeding method (p <0.05). Thus, the application of an anchovy substrate, either by chewing or smearing, increases fluoride intrusion on the enamel.

The protective effect of melatonin and Ganoderma lucidum against the negative effects of extremely low frequency electric and magnetic fields on pulp structure in rat teeth

ABSTRACTBackground/aim: The aim of this study was to determine whether Extremely low frequency electric and magnetic field (ELF-EMF) had any harmful effects on dental pulp tissue and examine histologically whether melatonin (MLT) and Ganoderma lucidum (GL) play a protective role against these harmful effects.Material and method: A total of 56 adult, male Wistar Albino rats were used in the study. The rats were separated into 8 equal groups and were exposed to ELF-EMF, generated by high voltage source, for 8 hours/day for 26 days – Groups I, II and III and for 52 days-Groups V, VI and VII. For sham-control groups (Groups IV and VIII for 26 and 52 days), rats were placed into same experimental set-up as exposure groups and same procedure was applied except ELF-EMF exposure. GL (20 mg/kg/day) and MLT (10 mg/kg/day) were administered by oral gavage and the intraperitoneal route respectively. At the end of the study, the rats anterior teeth were examined immunohistochemicaly using vimentin and vascular endothelial growth factor (VEGF).Results: Degeneration in the odontoblast cells, inflammatory cell infiltration, dilatation of the blood vessels and haemorrhagic changes were determined in the pulp of the rats in Groups I and V. A statistically significant difference was determined in the groups treated with MLT and GL (p < 0.05).Conclusion: It was determined that exposure to ELF-EMF induced histological changes in the dental pulp of rats, the using of MLT and GL could have a protective effect against these effects.

IMMUNE CELL PROFILE OF DENTAL PULP IN RATS TREATED WITH ZOLEDRONIC ACID

The objective of this study was to characterize the pulp immune cell profile in the teeth of rats treated with Zoledronic Acid (ZA). For this Male Wistar rats (n=6) received 4 intravenous infusions of ZA (0.04, 0.20 or 1.00 mg/kg) or saline. In the 70th day, they were euthanized. The first right molar was microscopically examined (H&E, toluidine blue and immunohistochemistry for CD68, Tumor Necrosis Factor (TNF)-α, Interleukin(IL)-1β, Inducible Nitric Oxide Synthase (iNOS), Nuclear Factor kappa B (NFkB) and IL-18 binding protein (IL-18bp). Were analyzed the ectasic/dilated vessels, the inflammatory cells (mast cells and mononuclear CD68 positive cells) and intensity of immunostaining for inflammatory markers in odontoblasts and non-odontoblasts pulp cells. Were used the Kruskall-Wallis/Dunn's and the chi-square tests (P<.05). There is no differences in number of animals exhibiting dilated/ectasia blood vessels (P=.242), inflammatory cells (P=.489) and in the number of mast cells (P=1.000). However, there was an augment of CD68 positive cells (P=.026), immunostaining of TNF-α (P=.020), IL-1β (P=.027), iNOS (P=.001) in odontoblasts and IL-1β (P=.027) in non-odontoblasts pulp cells dose-dependently. NFkB (nucleus and cytoplasm) and IL-18bp did not differ between groups. It was showed that ZA modified the immune cell profile in the dental pulp independent of NFkB.

Controlled release of lovastatin from poly(lactic-co-glycolic acid) nanoparticles for direct pulp capping in rat teeth.

Statin at appropriate concentrations has been shown to induce odontoblastic differentiation, dentinogenesis, and angiogenesis. However, using a carrier to control statin release might reduce toxicity and enhance its therapeutic effects. The aim of this study was to prepare poly(d,l-lactide-co-glycolide acid) (PLGA) nanoparticles that contain lovastatin for application in direct pulp capping. The PLGA–lovastatin particle size was determined using dynamic light scattering measurements and transmission electron microscopy. In addition, the release of lovastatin was quantified using a UV–Vis spectrophotometer. The cytotoxicity and alkaline phosphatase (ALP) activity of PLGA–lovastatin nanoparticles on human dental pulp cells were investigated. Moreover, a real-time polymerase chain reaction (PCR) assay, Western blot analysis, and an enzyme-linked immunosorbent assay (ELISA) were used to examine the osteogenesis gene and protein expression of dentin sialophosphoprotein (DSPP), dentin matrix acidic phosphoprotein 1 (DMP1), and osteocalcin (OCN). Finally, PLGA–lovastatin nanoparticles and mineral trioxide aggregate (MTA) were compared as direct pulp capping materials in Wistar rat teeth. The results showed that the median diameter of PLGA–lovastatin nanoparticles was 174.8 nm and the cumulative lovastatin release was 92% at the 44th day. PLGA–lovastatin nanoparticles demonstrated considerably a lower cytotoxicity than free lovastatin at 5, 9, and 13 days of culture. For ALP activity, the ALP amount of PLGA–lovastatin (100 μg/mL) was significantly higher than that of the other groups for 9 and 13 days of culture. The real-time PCR assay, Western blot analysis, and ELISA assay showed that PLGA–lovastatin (100 μg/mL) induced the highest mRNA and protein expression of DSPP, DMP1, and OCN in pulp cells. Histological evaluation of the animal studies revealed that MTA was superior to the PLGA–lovastatin in stimulating the formation of tubular dentin in an observation period of 2 weeks. However, in an observation period of 4 weeks, it was evident that the PLGA–lovastatin and MTA were competitive in the formation of tubular reparative dentin and a complete dentinal bridge.

RNA-Sequencing Analyses Demonstrate the Involvement of Canonical Transient Receptor Potential Channels in Rat Tooth Germ Development.

Tooth development depends on multiple molecular interactions between the dental epithelium and mesenchyme, which are derived from ectodermal and ectomesenchymal cells, respectively. We report on a systematic RNA sequencing analysis of transcriptional expression levels from the bud to hard tissue formation stages of rat tooth germ development. We found that GNAO1, ENO1, EFNB1, CALM1, SIAH2, ATP6V0A1, KDELR2, GTPBP1, POLR2C, SORT1, and members of the canonical transient receptor potential (TRPC) channel family are involved in tooth germ development. Furthermore, Cell Counting Kit 8 (CCK8) and Transwell migration assays were performed to explore the effects of these differentially expressed genes (DEGs) on the proliferation and migration of dental pulp stem cells. Immunostaining revealed that TRPC channels are expressed at varying levels during odontogenesis. The identified genes represent novel candidates that are likely to be vital for rat tooth germ development. Together, the results provide a valuable resource to elucidate the gene regulatory mechanisms underlying mammalian tooth germ development.

Effect of electromagnetic fields and antioxidants on the trace element content of rat teeth.

The purpose of this study was to examine the possible effect of extremely low-frequency electromagnetic fields (ELF-EMFs), from a high-voltage source, on rat teeth in terms of changes in trace elements (TEs) and the effect of antioxidants (melatonin [MLT] and Ganoderma lucidum [GL]) in counteracting these effects. We used adult male Wistar albino rats with a mean weight of 250–300 g and divided the rats into eight groups. The groups were subjected to an ELF-EMF that was applied with a high-voltage line for 8 hours/day for 26 days (Groups I, II, and III) or 52 days (Groups V, VI, and VII). Groups IV and VIII were the 26- and 52-day control/sham groups, respectively. Groups II and VI were treated with GL, and Groups III and VII were treated with MLT. MLT and GL were administered daily based on the weight of the animals and appropriate standards. At the end of the study, the rats were euthanized, and their anterior teeth were extracted. The teeth were preserved in pure water before evaluating the major TEs. At the end of the study, TE concentrations (in mg/kg) were assessed in the control and test groups. Compared with Group V, statistically significant differences in the concentrations of zinc (Zn) and strontium (Sr) were found for Group VII (ELF-EMF + MLT) (P<0.05). Therefore, ELF-EMF exposure can change the content of certain TEs in teeth and, after administering MLT and GL, the values of some of the TEs return to normal.

ラット抜歯窩創傷治癒過程にヒアルロン酸溶液が及ぼす影響(第486回 大阪歯科学会例会 抄録)

ラット抜歯窩創傷治癒過程にヒアルロン酸溶液が及ぼす影響(第486回 大阪歯科学会例会 抄録)

Protective Effect of Tamarindus Indica Fruit Pulp Extract on Expression of Type 1 Collagen in Teeth of Fluoride Exposed Rats

Purpose : The present study investigated the beneficial effect of Tamarindus indica fruit pulp extract on the expression of type 1 collagen gene in dentin of incisor teeth of fluoride exposed rats. Design/Methodology/Approach : Eighteen rats were randomly divided into three groups of six each. Group I served as control and received only tap water; group II received 200 ppm sodium fluoride in their drinking water and group III received fluorinated drinking water along with hydro-methanolic extract of T. indica fruit pulp (200 mg/kg body weight) daily by gavage for a period of 90 days. Dentin from incisor teeth was harvested at the end of the experiment for total RNA extraction. Findings : Fluoride exposed rats showed the down-regulation of expression of type 1 collagen (Col1a1) gene as compared to control. Co-administration of T. indica fruit pulp extract during exposure to fluoride through drinking water increases the expression of Col1a1 gene in dentin as compared to untreated fluoride exposed rats. Conclusion : It is concluded that daily oral administration T. indica fruit pulp extract had the protective effect on fluoride induced down regulation of type 1 collagen mRNA in dentin of incisor teeth of rats.

Immune cell profile of dental pulp tissue treated with zoledronic acid.

To characterize the pulp immune cell profile in the teeth of rats treated with zoledronic acid (ZA). Male Wistar rats (n=6 per group) received four intravenous infusions of ZA at doses of 0.04, 0.20 or 1.00mgkg-1 ZA or saline (control). On the 70th experimental day, they were euthanized. The first right molar was examined microscopically and submitted to toluidine blue reaction and immunohistochemical for CD68, tumour necrosis Factor (TNF)-α, interleukin (IL)-1β, inducible nitric oxide synthase (iNOS), nuclear factor kappa B (NF-kB) and IL-18 binding protein (IL-18bp). The presence of ectasic/dilated vessels and inflammatory cells was analysed, and mast cells and mononuclear CD68-positive cells were counted along with the intensity of immunostaining (0-3) for inflammatory markers in odontoblasts and nonodontoblasts pulp cells. The Kruskal-Wallis/Dunn's test (scores or quantitative data) and the chi-squared test (categorical data) were used (GraphPad Prism 5.0, P<0.05). There was no differences in the number of animals exhibiting dilated/ectasic blood vessels (P=0.242) and inflammatory cells (P=0.489) or in the number of mast cells (P=1.000). However, there was an increase in mononuclear CD68-positive cells (P=0.026), immunostaining of TNF-α (P=0.020), IL-1β (P=0.027) and iNOS (P=0.001) in odontoblasts, and IL-1β (P=0.013) in nonodontoblast pulp cells dose-dependently. NFkB (nucleus and cytoplasm) and IL-18bp did not differ between groups. ZA modified the immune cell profile in the dental pulp, increasing the number of macrophages and expression of pro-inflammatory markers independent of NFkB.

Histological evaluation of direct pulp capping with all-in-one adhesives in rat teeth.

The aim of this study was to histologically evaluate direct pulp capping using different all-in-one adhesives in rat teeth. Five all-in-one adhesives and a control material (MTA) were used. Each material was applied on the exposed pulp, and each cavity was subsequently restored with the resin composite. Rats were sacrificed 14 days after the surgical procedure. Serial stained sections were histologically evaluated for examining pulp tissue disorganization (PTD), inflammatory cell infiltration (ICI), dentin bridge formation (DBF), and bacterial penetration (BP). We found that rat pulps, which were direct capped with all-in-one adhesives, showed various degrees of PTD, ICI, and DBF depending on the material, and that there were no complete dentin bridges. In contrast, rat pulps capped with MTA showed no PTD and ICI, and there were complete dentin bridges in all, but one specimen. No BP was observed in any specimen.

Histologic evaluation of the effect of mineral trioxide aggregate-Fillapex as a root canal sealer in rat teeth submitted to late replantation.

Objective:This study aims to analyze the effect of new root canal based silicate cement, in rat teeth after late replantation, comparing with calcium hydroxide (CH) in preventing tooth root resorption.Materials and Methods:The study group included 16 Wistar rats in which the upper right central incisors were extracted and were left on a worktable for 60 min, simulating a case of tooth avulsion, after had been anesthetized. One group, (Group I), the canals were filled with CH past, before replantation. The second groups of teeth, (Group II), the canals were filled with mineral trioxide aggregate-Fillapex (MTAF). After removal, the blood clot of the socket, with saline solution irrigation, the teeth were replanted into their original socket, and splinted with silk 3/0. The rats were sacrificed 8 weeks after replantation and the specimens were prepared for histologic and histomorphometric analyses. The areas of inflammatory and replacement resorptions were selected and quantified. These data for each group of teeth were evaluated and analyzed using the Mann–Whitney test (P = 0.05).Result and Conclusion:All the replanted teeth in both groups survived. Although root canal filled with MTAF provide better results than with CH past concerning inflammatory and replacement resorption, there was no statistical difference (P = 0.527).

Pancreatic duct ascariasis: Case series

Background and Objectives:Although uncommon in the West, Ascaris lumbricoides is a common cause of acute pancreatitis in developing countries. The mechanism of acute pancreatitis in ascariasis may be due to obstruction of papilla of Vater, invasion of common bile duct (CBD), or pancreatic duct (PD). The invasion of PD occurs rarely owing to its smaller caliber. Ultrasonography (USG) is an effective tool for the diagnosis of biliary and pancreatic ascariasis; however, the diagnosis may be false negative in up to 30% of cases. Pancreatic ascariasis is a rare entity. We present our retrospective data of last 10 years of 15 cases of pancreatic ascariasis.Methods:During a study period of 10 years, 15 cases of pancreatic ascariasis were diagnosed by USG/endoscopic ultrasonography (EUS). EUS was performed with a linear or radial echoendoscope. Thirteen patients presented with symptoms of acute pancreatitis. Out of 13 patients, nine presented with first episode of idiopathic pancreatitis while four presented with idiopathic recurrent acute pancreatitis. One patient had biliary colic and one patient presented with acute cholangitis. Twelve patients had mild pancreatitis while only one had moderate pancreatitis. Only two cases were diagnosed with USG while 13 patients were diagnosed with EUS. Out of 15 patients, 14 underwent side viewing endoscopy with removal of live single/multiple worms with rat tooth forceps/biopsy forceps/dormia basket in 13 patients. Two patients were managed conservatively with repeat USG showing absence of ascariasis. There were no complications.Results:Two patients had associated bile duct ascariasis. EUS features were single or multiple linear hyperechoic structure without acoustic shadowing in the PD or CBD or with central hypoechoic tube, representing alimentary canal of the worm and movements of worms inside the duct. Live roundworms were removed from CBD and PD without undertaking sphincterotomy. In endemic areas, sphincterotomy facilitates the risk of migration of worms into the CBD.Conclusion:Ascariasis-induced acute pancreatitis is mild and EUS is the investigation of choice. The recurrence is rare and treatment is side viewing endoscopy with removal of worms. Although USG is quite sensitive for diagnosing biliary and pancreatic ascariasis, its sensitivity significantly falls when the worm is thin, in the PD, or the CBD is non-dilated. EUS should be used early in the workup of idiopathic acute pancreatitis after the first episode.

Pancreatic duct ascariasis: Case series

Background and Objectives:Ascaris lumbricoides is a common cause of acute pancreatitis in the developing countries. Ultrasonography (USG) is a useful tool for the diagnosis; however, the diagnosis may be false negative in up to 30% of cases.Materials and Methods:During a study period of 10 years, 15 cases of pancreatic ascariasis were diagnosed by USG/endoscopic ultrasound (EUS). Thirteen patients presented with symptoms of acute pancreatitis. Of 13 patients, nine presented with first episode of idiopathic pancreatitis while four presented with idiopathic recurrent acute pancreatitis. One patient had biliary colic and one patient presented with acute cholangitis. Twelve patients had mild pancreatitis while only one had moderate pancreatitis. Only two cases were diagnosed with USG while 13 patients were diagnosed with EUS. The patients underwent side viewing endoscopy/endoscopic retrograde cholangiopancreatography under the same sedation after EUS if EUS revealed biliary/pancreatic ascariasis. Of 15 patients, 14 underwent side viewing endoscopy with removal of live single/multiple worms with rat tooth forceps/Dormia basket in 13 patients. Two patients were managed conservatively with repeat USG showing the absence of ascariasis. There were no complications.Results:EUS features were single or multiple linear hyperechoic structure without acoustic shadowing in the pancreas divisum with central anechoic tube representing alimentary canal of the worm. Live roundworms were removed from papilla without undertaking sphincterotomy. In endemic areas, sphincterotomy facilitates the risk of migration of worms into the common bile duct.Conclusions:Ascariasis-induced acute pancreatitis is mild and EUS is the investigation of choice. The recurrence is rare and treatment is side viewing endoscopy with removal of worms.

A preliminary study of effects of low-intensity pulsed ultrasound (LIPUS) irradiation on dentoalveolar ankylosis.

The purpose of this experiment was to investigate whether low-intensity pulsed ultrasound (LIPUS) irradiation can inhibit dentoalveolar ankylosis in transplanted rat teeth. LIPUS irradiation (the pulsed ultrasound signal had a frequency of 3.0 MHz, a spatial average intensity of 30 mW/cm2, and a pulse ratio of 1:4) was performed on the face over the re-planted teeth of rats for 4 weeks. After the rats were euthanized, we measured mobility (Periotest value [PTV]) of the transplanted and control teeth using a Periotest. Finally, we performed histological evaluation to detect ankylosis. PTVs tended to be significantly lower for re-planted teeth than for control teeth. Histological evaluation revealed that the roots of all re-planted teeth were coalescent with alveolar bone. Furthermore, no ankylosis was observed in three-fifths of the re-planted teeth following LIPUS irradiation. These results indicate the potential efficacy of LIPUS to inhibit dentoalveolar ankylosis.

Bcl11b regulates enamel matrix protein expression and dental epithelial cell differentiation during rat tooth development.

Amelogenesis, beginning with thickened epithelial aggregation and ending with highly mineralized enamel formation, is a process mediated by a complex signaling network that involves several molecules, including growth and transcription factors. During early tooth development, the transcription factor B‑cellCLL/lymphoma11B (Bcl11b) participates in dental epithelial cell proliferation and differentiation. However, whether it affects the postnatal regulation of enamel matrix protein expression and ameloblast differentiation remains unclear. To clarify the role of Bcl11b in enamel development, the present study initially detected the protein expression levels of Bcl11b during tooth development using immunohistochemistry, from the embryonic lamina stage to the postnatal period, and demonstrated that Bcl11b is predominantly restricted to cervical loop epithelial cells at the cap and bell stages, whereas expression is reduced in ameloblasts. Notably, the expression pattern of Bcl11b during tooth development differed between rats and mice. Knockdown of Bcl11b by specific small interfering RNA attenuated the expression of enamel‑associated genes, including amelogenin, X‑linked (Amelx), ameloblastin (Ambn), enamelin (Enam), kallikrein related peptidase4 (Klk4), matrix metallopeptidase20 and Msh homeobox2 (Msx2). Chromatin immunoprecipitation assay verified that Msx2 was a transcriptional target of Bcl11b. However, overexpression of Msx2 resulted in downregulation of enamel‑associated genes, including Ambn, Amelx, Enam and Klk4. The present study suggested that Bcl11b serves a potentially important role in the regulation of ameloblast differentiation and enamel matrix protein expression. In addition, a complex feedback regulatory network may exist between Bcl11b and Msx2.

Proteomic Analysis of Dental Tissue Microsamples.

Improved understanding of dental enamel development will benefit not only dentistry but also biomedicine more generally. Rat and mouse models of enamel development are relatively well characterized and experimentally powerful. However, the diminutive size of murine teeth makes them difficult to study using standard proteomics approaches. Here, we describe gel-based proteomic methods that enable parallel quantification, identification, and functional characterization of proteins from developing rat and mouse teeth. These refined methods are applicable to other scarce samples including human enamel defects.