Deficiency of Trps1 in Cementoblasts Impairs Cementogenesis and Tooth Root Formation.

Cementum is the least studied of all mineralized tissues and little is known about mechanisms regulating its formation. Therefore, the goal of this study was to provide new insights into the transcriptional regulation of cementum formation by determining the consequences of the deficiency of the Trps1 transcription factor in cementoblasts. We used Trps1Col1a1 cKO (2.3Co1a1-CreERT2;Trps1fl/fl) mice, in which Trps1 is deleted in cementoblasts. Micro-computed tomography analyses of molars of 4-week-old males and females demonstrated significantly shorter roots with thinner mineralized tissues (root dentin and cementum) in Trps1Col1a1 cKO compared to WT mice. Semi-quantitative histological analyses revealed a significantly reduced area of cellular cementum and localized deficiencies of acellular cementum in Trps1Col1a1 cKO mice. Immunohistochemical analyses revealed clustering of cementoblasts at the apex of roots, and intermittent absence of cementoblasts on Trps1Col1a1 cKO cementum surfaces. Fewer Osterix-positive cells adjacent to cellular cementum were also detected in Trps1Col1a1 cKO compared to WT mice. Decreased levels of tissue-nonspecific alkaline phosphatase (TNAP), an enzyme required for proper cementogenesis, were apparent in cementum, periodontal ligament, and alveolar bone of Trps1Col1a1 cKO. There were no apparent differences in levels of bone sialoprotein (Bsp) in cementum. Quantitative analyses of picrosirius red-stained periodontal ligament revealed shorter and disorganized collagen fibers in Trps1Col1a1 cKO mice demonstrating impaired periodontal structure. In conclusion, this study has identified Trps1 transcription factor as one of the important regulators of cellular and acellular cementum formation. Furthermore, this study suggests that Trps1 supports the function of cementoblasts by upregulating expression of the major proteins required for cementogenesis, such as Osterix and TNAP.

Trps1 transcription factor regulates mineralization of dental tissues and proliferation of tooth organ cells.

Mutations of the TRPS1 gene cause trichorhinophalangeal syndrome (TRPS), a skeletal dysplasia with dental abnormalities. TRPS dental phenotypes suggest that TRPS1 regulates multiple aspects of odontogenesis, including the tooth number and size. Previous studies delineating Trps1 expression throughout embryonic tooth development in mice detected strong Trps1 expression in dental mesenchyme, preodontoblasts, and dental follicles, suggesting that TRPS dental phenotypes result from abnormalities in early developmental processes. In this study, Trps1+/- and Trps1-/- mice were analyzed to determine consequences of Trps1 deficiency on odontogenesis. We focused on the aspects of tooth formation that are disturbed in TRPS and on potential molecular abnormalities underlying TRPS dental phenotypes. Microcomputed tomography analyses of molars were used to determine tooth size, crown shape, and mineralization of dental tissues. These analyses uncovered that disruption of one Trps1 allele is sufficient to impair mineralization of dentin in both male and female mice. Enamel mineral density was decreased only in males, while mineralization of the root dental tissues was decreased only in females. In addition, significantly smaller teeth were detected in Trps1+/- females. Histomorphometric analyses of tooth organs showed reduced anterior-posterior diameter in Trps1-/- mice. BrdU-incorporation assay detected reduced proliferation of mesenchymal and epithelial cells in Trps1-/- tooth organs. Immunohistochemistry for Runx2 and Osx osteogenic transcription factors revealed changes in their spatial distribution in Trps1-/- tooth organs and uncovered cell-type specific requirements of Trps1 for Osx expression. In conclusion, this study has demonstrated that Trps1 is a positive regulator of cell proliferation in both dental mesenchyme and epithelium, suggesting that the microdontia in TRPS is likely due to decreased cell proliferation in developing tooth organs. Furthermore, the reduced mineralization observed in Trps1+/- mice may provide some explanation for the extensive dental caries reported in TRPS patients.

Deficiency of Mineralization-Regulating Transcription Factor Trps1 Compromises Quality of Dental Tissues and Increases Susceptibility to Dental Caries.

Dental caries is the most common chronic disease in children and adults worldwide. The complex etiology of dental caries includes environmental factors as well as host genetics, which together contribute to inter-individual variation in susceptibility. The goal of this study was to provide insights into the molecular pathology underlying increased predisposition to dental caries in trichorhinophalangeal syndrome (TRPS). This rare inherited skeletal dysplasia is caused by mutations in the TRPS1 gene coding for the TRPS1 transcription factor. Considering Trps1 expression in odontoblasts, where Trps1 supports expression of multiple mineralization-related genes, we focused on determining the consequences of odontoblast-specific Trps1 deficiency on the quality of dental tissues. We generated a conditional Trps1 Col1a1 knockout mouse, in which Trps1 is deleted in differentiated odontoblasts using 2.3kbCol1a1-Cre ERT2 driver. Mandibular first molars of 4wk old male and female mice were analyzed by micro-computed tomography (µCT) and histology. Mechanical properties of dentin and enamel were analyzed by Vickers microhardness test. The susceptibility to acid demineralization was compared between WT and Trps1 Col1a1 cKO molars using an ex vivo artificial caries procedure. µCT analyses demonstrated that odontoblast-specific deletion of Trps1 results in decreased dentin volume in male and female mice, while no significant differences were detected in dentin mineral density. However, histology revealed a wider predentin layer and the presence of globular dentin, which are indicative of disturbed mineralization. The secondary effect on enamel was also detected, with both dentin and enamel of Trps1 Col1a1 cKO mice being more susceptible to demineralization than WT tissues. The quality of dental tissues was particularly impaired in molar pits, which are sites highly susceptible to dental caries in human teeth. Interestingly, Trps1 Col1a1 cKO males demonstrated a stronger phenotype than females, which calls for attention to genetically-driven sex differences in predisposition to dental caries. In conclusion, the analyses of Trps1 Col1a1 cKO mice suggest that compromised quality of dental tissues contributes to the high prevalence of dental caries in TRPS patients. Furthermore, our results suggest that TRPS patients will benefit particularly from improved dental caries prevention strategies tailored for individuals genetically predisposed due to developmental defects in tooth mineralization.

Conversion of α-Cells to ß-Cells in the Postpartum Mouse Pancreas Involves Lgr5 Progeny.

In contrast to the skin and the gut, where somatic stem cells and their niche are well characterized, a definitive pancreatic multipotent cell population in the adult pancreas has yet to be revealed. Of particular interest is whether such cells may be endogenous in patients with diabetes, and if so, can they be used for therapeutic purposes? In the current study, we used two separate reporter lines to target Cre-recombinase expression to the Lgr5- or glucagon-expressing cells in the pancreas. We provide evidence for the existence of a population of cells within and in the proximity of the ducts that transiently express the stem-cell marker Lgr5 during late gestational stages. Careful timing of tamoxifen treatment in Lgr5EGFP-IRES-CreERT2 ;R26 Tomato mice allowed us to show that these Lgr5-expressing progenitor cells can differentiate into α-cells during pregnancy. Furthermore, we report on a spontaneous lineage conversion of α- to ß-cells specifically after parturition. The contribution of Lgr5 progeny to the ß-cell compartment through an α-cell intermediate phase early after pregnancy appears to be part of a novel mechanism that would counterbalance against excessive ß-cell mass reduction during ß-cell involution.

Trps1 transcription factor represses phosphate-induced expression of SerpinB2 in osteogenic cells.

Serine protease inhibitor SerpinB2 is one of the most upregulated proteins following cellular stress. This multifunctional serpin has been attributed a number of pleiotropic activities, including roles in cell survival, proliferation, differentiation, immunity and extracellular matrix (ECM) remodeling. Studies of cancer cells demonstrated that expression of SerpinB2 is directly repressed by the Trps1 transcription factor, which is a regulator of skeletal and dental tissues mineralization. In our previous studies, we identified SerpinB2 as one of the novel genes highly upregulated by phosphate (Pi) at the initiation of the mineralization process, however SerpinB2 has never been implicated in formation nor homeostasis of mineralized tissues. The aim of this study was to establish, if SerpinB2 is involved in function of cells producing mineralized ECM and to determine the interplay between Pi signaling and Trps1 in the regulation of SerpinB2 expression specifically in cells producing mineralized ECM. Analyses of the SerpinB2 expression pattern in mouse skeletal and dental tissues detected high SerpinB2 protein levels specifically in cells producing mineralized ECM. qRT-PCR and Western blot analyses demonstrated that SerpinB2 expression is activated by elevated Pi specifically in osteogenic cells. However, the Pi-induced SerpinB2 expression was diminished by overexpression of Trps1. Decreased SerpinB2 levels were also detected in osteoblasts and odontoblasts of 2.3Col1a1-Trps1 transgenic mice. Chromatin immunoprecipitation assay (ChIP) revealed that the occupancy of Trps1 on regulatory elements in the SerpinB2 gene changes in response to Pi. In vitro functional assessment of the consequences of SerpinB2 deficiency in cells producing mineralized ECM detected impaired mineralization in SerpinB2-deficient cells in comparison with controls. In conclusion, high and specific expression of SerpinB2 in cells producing mineralized ECM, the impaired mineralization of SerpinB2-deficient cells and regulation of SerpinB2 expression by two molecules regulating formation of mineralized tissues suggest involvement of SerpinB2 in physiological mineralization.

Reactive oxygen species (ROS) generation as an underlying mechanism of inorganic phosphate (Pi)-induced mineralization of osteogenic cells.

Reactive Oxygen Species (ROS) are a natural byproduct of oxygen metabolism. At physiological levels, ROS regulate multiple cellular processes like proliferation, migration, and differentiation. Increased levels of ROS are associated with pathological conditions, such as inflammation and vascular calcification, where they elicit cytotoxic effects. These contrasting outcomes of ROS have also been reported in osteogenic precursor cells. However, the role of ROS in committed osteogenic cells has not been investigated. Cytotoxic and physiologic effects have also been demonstrated for extracellular phosphate (Pi). Specifically, in committed osteogenic cells Pi stimulates their major function (mineralization), however in osteogenic precursors and endothelial cells Pi cytotoxicity has been reported. Interestingly, Pi cytotoxic effects have been associated with ROS production in the pathological vascular mineralization. In this study, we investigated a molecular mechanistic link between elevated Pi and ROS production in the context of the mineralization function of committed osteogenic cells. Using committed osteogenic cells, 17IIA11 odontoblast-like cell and MLO-A5 osteoblast cell lines, we have unveil that Pi enhances intracellular ROS production. Furthermore, using a combination of mineralization assays and gene expression analyses, we determined that Pi-induced intracellular ROS supports the physiological mineralization process. In contrast, the exogenous ROS, provided in a form of H2O2, was detrimental for osteogenic cells. By comparing molecular signaling cascades induced by extracellular ROS and Pi, we identified differences in signaling routes that determine physiologic versus toxic effect of ROS on osteogenic cells. Specifically, while both extracellular and Pi-induced intracellular ROS utilize Erk1/2 signaling mediator, only extracellular ROS induces stress-activated mitogen-activated protein kinases P38 and JNK that are associated with cell death. In summary, our results uncovered a physiological role of ROS in the Pi-induced mineralization through the molecular pathway that is distinct from ROS-induced cytotoxic effects.

Frequency and distribution of Mutans Streptococci in dental plaque from caries-free and caries-affected Venezuelan children.

Mutans Streptococci, in particular S. mutans and S. sobrinus, are generally considered to be the prime etiological bacteria of human dental caries. The aim of this study was to determine the frequency of mutans streptococci in dental plaque in three groups of caries-free and caries-affected Venezuelan children aged 2-6, 7-12, 13-19 years, and their possible association with dental caries. The frequency of mutans streptococci was determined in samples of pooled dental plaque collected from all detectable sources of 30 (62.5%) caries-affected and 18 (37.5%) caries-free children. The samples were collected from all available tooth sites using a Hollenbak probe and immediately suspended in Ringer's solution, serially diluted and cultured in Mitis Salivarius (MS) agar for total streptococci determination and Mitis Salivarius Bacitracin (MSB) for isolation of mutans streptococci. The bacterial identification procedure was done using the API Rapid Strep System. The criteria used to determine dmft and DMFT was established by Klein and Palmer (1941). Mean dmft and DMFT were 6.4 +/- 3.2 and 4.4 +/- 2.9, respectively. Ten (33%) out of 30 caries-affected children harbored mutans streptococci. The species most frequently found were S. mutans (20%), S. sobrinus (10%) and S. rattus (3.3%). Meanwhile, in the caries-free group only 6 out of 18 children (33%) harbored mutans streptococci, specifically S. mutans and S. sobrinus, both at 17%, with no significant difference between the two groups. These results indicate that the percentage of children that harbored mutans streptococci was similar in both groups, suggesting that other acidogenic species may be responsible for caries development.

Prolactin Promotes Fibrosis and Pancreatic Cancer Progression.

Pancreatic ductal adenocarcinoma (PDAC) is associated with significant fibrosis. Recent findings have highlighted the profibrotic activity of tissue-resident macrophages in the pancreatic cancer microenvironment. Here, we show that neoplastic pancreatic epithelium, as well as a subset of tissue-resident macrophages, expresses the prolactin-receptor (PRLR). High mobility group box 1-induced prolactin expression in the pancreas maintained FAK1 and STAT3 phosphorylation within the epithelium and stroma. Gain-of-function and loss-of-function experiments demonstrated the essential role of prolactin in promoting collagen deposition and fibrosis. Finally, the signaling cascade downstream of prolactin/PRLR activated STAT3 rather than STAT5 in PDAC. These findings suggest that targeting prolactin together with IL6, a known major activator of STAT3, could represent a novel therapeutic strategy for treating pancreatic cancer. SIGNIFICANCE: Prolactin is a key factor in the cross-talk between the stroma and neoplastic epithelium, functioning to promote fibrosis and PDAC progression.

[Dental caries and fluorosis in children consuming water with different fluoride concentrations in Maiquetia, Vargas State, Venezuela]. / Experiencia de caries y fluorosis dental en escolares que consumen agua con diferentes concentraciones de fluoruro en Maiquetía, Estado Vargas, Venezuela.

The objective of this study was to determine the experience of fluorosis and dental caries in 8- 12 year old children that drink water with different fluoride concentrations, from Maiquetía, Vargas State. Four hundred and twenty-one children were evaluated and divided in groups of 84 children each, according with their age (8-9-10-11) but 85 for the age 12. This evaluation was developed by a calibrated dentist using Dean's Index for dental fluorosis examining only the six upper anterior teeth and DMFT/dmft index to determine dental caries, following the criteria established by the WHO. In addition, a social status questionnaire was given to the subjects and samples of water and salt from the communities were collected. Thirty-three per cent of the children in this study were males and 67% were females. Results indicated that the mean DMFT and dmft were 0.91 and 1.88, respectively, showing a total of 2.17 teeth with dental caries being the decayed component, the highest component observed in both dentitions. The mean prevalence of dental fluorosis for the studied population was 16.6%, where the very mild category (8.5%) predominated. Maria May was the most affected school with dental fluorosis (41.5%) and the fluoride concentration in drinking water after analyses was 1.58%. The results of this study indicate the presence of an inverse relationship between fluoride concentrations in the water collected at the schools and the prevalence of dental fluorosis in the permanent dentition of school children, but not in the primary dentition.

Identification of Newly Committed Pancreatic Cells in the Adult Mouse Pancreas.

Multipotent epithelial cells with high Aldehyde dehydrogenase activity have been previously reported to exist in the adult pancreas. However, whether they represent true progenitor cells remains controversial. In this study, we isolated and characterized cells with ALDH activity in the adult mouse or human pancreas during physiological conditions or injury. We found that cells with ALDH activity are abundant in the mouse pancreas during early postnatal growth, pregnancy, and in mouse models of pancreatitis and type 1 diabetes (T1D). Importantly, a similar population of cells is found abundantly in healthy children, or in patients with pancreatitis or T1D. We further demonstrate that cells with ALDH activity can commit to either endocrine or acinar lineages, and can be divided into four sub-populations based on CD90 and Ecadherin expression. Finally, our in vitro and in vivo studies show that the progeny of ALDH1+/CD90-/Ecad- cells residing in the adult mouse pancreas have the ability to initiate Pancreatic and duodenal homeobox (Pdx1) expression for the first time. In summary, we provide evidence for the existence of a sortable population of multipotent non-epithelial cells in the adult pancreas that can commit to the pancreatic lineage following proliferation and mesenchymal to epithelial transition (MET).

The eicosapentaenoic acid metabolite 15-deoxy-δ(12,14)-prostaglandin J3 increases adiponectin secretion by adipocytes partly via a PPARγ-dependent mechanism.

The intake of ω-3 polyunsaturated fatty acids (PUFAs), which are abundant in marine fish meat and oil, has been shown to exert many beneficial effects. The mechanisms behind those effects are numerous, including interference with the arachidonic acid cascade that produces pro-inflammatory eicosanoids, formation of novel bioactive lipid mediators, and change in the pattern of secreted adipocytokines. In our study, we show that eicosapentaenoic acid (EPA) increases secreted adiponectin from 3T3-L1 adipocytes and in plasma of mice as early as 4 days after initiation of an EPA-rich diet. Using 3T3-L1 adipocytes, we report for the first time that 15-deoxy-δ(12,14)-PGJ3 (15d-PGJ3), a product of EPA, also increases the secretion of adiponectin. We demonstrate that the increased adiponectin secretion induced by 15d-PGJ3 is partially peroxisome proliferator-activated receptor-gamma (PPAR-γ)-mediated. Finally, we show that 3T3-L1 adipocytes can synthesize 15d-PGJ3 from EPA. 15d-PGJ3 was also detected in adipose tissue from EPA-fed mice. Thus, these studies provide a novel mechanism(s) for the therapeutic benefits of ω-3 polyunsaturated fatty acids dietary supplementation.

Prevalencia de caries dental y fluorosis en áreas de fluorosis endémica en el Estado Portuguesa, Venezuela / Prevalence of dental caries and flurosis endemic fluorosis areas of Portuguesa State, Venezuela

Determinar la prevalencia y severidad de caries y fluorosis dental en una zona de fluorosis endémica en Portuguesa. 187 individuos entre 2-62 años de edad de cuatro comunidades del Municipio Santa Rosalía fueron evaluados para caries dental según el índice CPOD/ceo (OMS) y para fluorosis dental de acuerdo al Índice de Dean. Todos los participantes en la presente investigación firmaron un consentimiento informado. Cada paciente respondió un cuestionario estructurado a tal fin y los datos fueron registrados. El examen clínico fue realizado por un examinador calibrado y se utilizó sonda WHO, espejo plano #5 y luz natural. Según el género, de los 187 pacientes, 96 fueron masculino (51%) y 91 femeninos (49%) y 90,9% de la población estudiada pertenecía a los estratos 4 y 5 de Graffar. El 69% de pacientes estaban libres de caries dental y los índices promedio CPOD y ceo fueron 1,7±3,62 y 0,41±1,15, respectivamente siendo el índice CPOD en Cogote significativamente menor (p<0,05) al compararlos con los observados en San Pablo y Playón (p>0,05), pero sin diferencias significativas al compararlo con el de Punto Fijo. El 76,9% de los individuos evaluados presentaban fluorosis dental siendo el grado de severidad promedio la categoría de moderado (Grado 4). Se le debe dar una alta prioridad a la defluoruración del agua, y en caso de que no sea posible, se debe proveer a la población de agua con concentraciones de fluoruro óptimas. No se observó asociación entre el grado de severidad de fluorosis dental y los niveles de fluoruro en el agua. Estudio parcialmente financiado por la Facultad de Odontología, UCV.

The purpose of this study was to determine the prevalence and severity of dental caries and fluorosis in an endemic area of Portuguesa State. One hundred eighty seven individuals, age ranging between 2-62 years, from four communities of Santa Rosalía Municipality were evaluated for dental caries index DMFT/dmf according to the WHO criteria and dental fluorosis using the Dean index. All participants signed the written consent to be enrolled for the study. The clinical examination was done by a calibrated examiner using the WHO probe, mirror #5 and natural light. The results from the study showed that 96/187 (51%) were male and 91/187 (49%) were female. According to socioeconomic status 90.9% of the studied population was level 4 and 5 according to Graffar criteria. Sixty nine percent of the patient was dental caries free and the mean indexes DMFT/dmf were 1.7±3.62 and 0.41±1.15, respectively. The lower DMFT scores were observed in Cogote (p<0.05) with statistical significant differences when compared to San Pablo and Playón but without differences when compares to Punto Fijo community (p>0.05). When analyzing the presence of dental fluorosis, 76.9% of the subjects had the condition being moderate (Grade 4). We may conclude that water defluoridation is of high priority in these communities, as well as to provide the population with optimal fluoride concentration in water. Our results indicate the absence of association between the fluoride concentration for water consumption and the dental fluorosis severity in endemic areas. Study partially supported by the Faculty of Dentistry, UCV.

Experiencia de caries y fluorosis dental en escolares que consumen agua con diferentes concentraciones de fluoruro en Maiquetía Estado Vargas Venezuela / Dental caries and fluorosis in children consuming water with different fluoride concentrations in Maiquetía Vargas State Venezuela

El objetivo del estudio fue determinar la experiencia de caries y fluorosis dental en escolares que consumen agua con diferentes concentraciones de fluoruro en Maiquetía, Estado Vargas, Venezuela. Se examinaron 421 niños distribuidos en grupos de 84 niños para las edades de 8, 9, 10, 11 y 85 para la edad de 12 años. El examen clínico fue realizado por un personal calibrado, se utilizó el índice de Dean para fluorosis dental para lo cual se examinaron los 6 dientes antero-superiores y el índice CPOD y ceod para caries dental, según los criterios propuesto por la OMS. Adicionalmente se realizó una encuesta socioeconómica y se tomaron muestras de agua y de sal en la localidad. De la muestra seleccionada el 33 por ciento fueron niños y el 67 por ciento niñas. Los resultados revelaron un índice CPOD promedio de 0,91, un ceod de 1,88 y un promedio total de dientes afectados por caries de 2,17. De igual manera se identificó el componente cariado como el más elevado en ambas denticiones. La prevalencia promedio de fluorosis dental para toda la población evaluada fue de 16,6 por ciento, siendo más frecuente el grado de fluorosis muy leve (8,5 por ciento). La Unidad Educativa María May fue la más afectada por fluorosis dental (41,5 por ciento) y la concentración de fluoruro en el agua recolectada de esta unidad educativa fue de 1,58 ppm. De acuerdo a los resultados obtenidos en este estudio se concluye que existe una relación inversa entre la concentración de fluoruro presente en las aguas de los colegios y la prevalencia de fluorosis dental en la dentición permanente de los niños evaluados, pero no en la dentición primaria.

Hábitos de higiene bucal y el nivel socioeconómico de niños entre 15 y 20 meses de edad / Oral hygiene habits and socioeconomic level of 15- to 20-year-old children

Tooth brushing and dentifrice use have been undoubtedly reported by several studies as the primary oral hygiene practices carried out to reduce and control caries development, observing differences among social levels. Objective: The aim of this study was to associate oral hygiene habits with the social levels of children among 15 to 20 months. Methods: One hundred and twelve children were selected from 10 different daycare centers. The criteria of selection included, children among 15 to 20 months, apparently healthy, with a consent form signed by the parent and attending the daycare. Questionnaires assessed tooth-brushing patterns and fluoride dentifrice use considering other possible oral hygiene practices developed at the moment and reporting when these were initiated. A socioeconomic form was also completed for each child. Results: According to Graffar, only 39.3% belonged to the lower social class and the rest of the children (21.4%-39.3%) were classified within the middle and the higher social levels, respectively. The average age of introducing oral hygiene habits was 12.8 months. From the 112 children evaluated, 42 (37.5%) developed any oral hygiene routine, 19.0% of the children's teeth were brushed or cleaned only with water, 76.2% of them used fluoridated dentifrice, and 81.3% of the mothers placed the dentifrice on the toothbrush. Conclusions: The results of this study showed the absence of a significant relationship between parents' socioeconomic status and dental hygiene habits observed in children between 15 to 20 months of age. An important finding was that a high percentage of the children at this age did not show any oral hygiene habit, as well as, mothers played the most important role.

Numerosos estudios han reportado que el cepillado y el uso de cremas dentales fluoruradas constituyen uno de los principales hábitos de higiene bucal destinados a la disminución y control de la caries dental, cuya práctica podría variar según el estrato socio-económico. Objetivo: El propósito fundamental de éste estudio fue el de asociar la práctica de hábitos de higiene bucal con el estrato social en niños entre 15 y 20 meses. Materiales y métodos: Un total de 112 niños fueron seleccionados de 10 maternales ubicados en la Zona Metropolitana de Caracas. Se completo un cuestionario que registraría información acerca de los patrones de cepillado, el uso de cremas dentales fluoruradas y la posible práctica de otros hábitos de higiene bucal. Una encuesta socio-económica según los criterios de Graffar modificado por Méndez Castellano 1986 también fue registrada para cada niño. Resultados: De acuerdo con la encuesta socio-económica solo el 39,3 por ciento de los niños pertenecía a los estratos más bajos, el resto de los niños formaba parte de los estratos Alto-medio alto y medio (21,4 por ciento-39,3 por ciento) respectivamente. El promedio de la edad de inicio de alguna práctica de higiene bucal fue de 12,8 meses. De los 112 niños evaluados solo 42 (37,5 por ciento) tenían algún hábito de cuidado bucal. Por otra parte, el 19,0 por ciento se cepillaba solo con agua y 4,8 por ciento no incluía el cepillo en la limpieza de sus dientes. El 81,3 por ciento de las madres colocaba la crema dental en el cepillo y asistía al niño durante el cepillado. Conclusiones: Los resultados de este estudio indicaron la ausencia de una relación significativa entre la práctica de hábitos de higiene bucal y el nivel socioeconómico de los padres. Cabe mencionar como un hallazgo importante que un alto porcentaje de los niños a estas edades aun no se cepillan y las madres siguen jugando un papel fundamental en las rutinas de cuidado bucal.