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This article reviews general aspects about the epithelial cell rests of Malassez (ERM). The historical and general morphological features of the ERM are briefly described. The embryological derivation of the ERM is presented as an important consideration in understanding the events associated with their origin and possible functional roles within the periodontal ligament. The ultrastructural description of the ERM is also included to complement the morphological characteristics which distinguish these cells as the unique epithelial element of the periodontal ligament. The unique ability of these cells to synthesize and secrete a number of proteins usually associated with cells of mesenchymal origin, rather than ectodermal origin, is discussed in light of their role in cementum repair and regeneration. Such considerations lead to our hypothesis that one of the functional roles of the ERM may lie not only their role in maintaining and contributing to the normal periodontal cellular elements and function but also contributing, in a significant manner, to periodontal regeneration.

Regeneration of osseous defects by a tissue-engineering approach provides a novel means of treatment utilizing cell biology, materials science, and molecular biology. In this study the concept of tissue engineering was tested with collagen type I matrices seeded with cells with osteogenic potential and implanted into sites where osseous damage had occurred. Explant cultures of cells from human alveolar bone and gingiva were established. When seeded into a three-dimensional type I collagen-based scaffold, the bone-derived cells maintained their osteoblastic phenotype as monitored by mRNA and protein levels of the bone-related proteins including bone sialoprotein, osteocalcin, osteopontin, bone morphogenetic proteins 2 and 4, and alkaline phosphatase. These in vitro-developed matrices were implanted into critical-size bone defects in skulls of immunodeficient (SCID) mice. Wound healing was monitored for up to 4 weeks. When measured by microdensitometry the bone density within defects filled with osteoblast-derived matrix was significantly higher compared with defects filled with either collagen scaffold alone or collagen scaffold impregnated with gingival fibroblasts. New bone formation was found at all the sites treated with the osteoblast-derived matrix at 28 days, whereas no obvious new bone formation was identified at the same time point in the control groups. In situ hybridization for the human-specific Alu gene sequence indicated that the newly formed bone tissue resulted from both transplanted human osteoblasts and endogenous mesenchymal stem cells. The results indicate that cells derived from human alveolar bone can be incorporated into bioengineered scaffolds and synthesize a matrix, which on implantation can induce new bone formation.

Acid demineralization of teeth causes occlusal erosion and attrition and associated non-carious cervical lesions at sites relatively unprotected by saliva. Associations of occlusal pathology and cervical lesions were looked for in 450 patients with toothwear, and 174 subjects with cervical lesions were identified. Associations of occlusal attrition, or erosion, or no wear, with cervical lesions at 72 buccal and lingual sites were recorded from epoxy resin replicas of the subjects' dentitions (3241 teeth). Criteria used to discriminate occlusal erosion from attrition; and shallow from grooved and wedge-shaped cervical lesions were delineated by scanning electron microscopy (SEM). In the absence of occlusal pathology, cervical lesions were very rare (<1%). In the presence of occlusal pathology, cervical lesions were present in 27.71% of buccal sites as opposed to 2.61% of lingual sites. The commonest site of cervical lesions was the facial of maxillary incisors (36% of sites). The least common site was the lingual aspect of mandibular molars (1.7% of sites). These differences may reflect the normal protective role of serous saliva and salivary pellicle in a site-specific manner, on the lingual surfaces of mandibular teeth particularly, and do not support abfraction as the prime aetiology of cervical lesions.

Purpose The lack of an ongoing surveillance system for hemoglobinopathies in the United States impedes the ability of public health organizations to identify individuals with these conditions, monitor their health-care utilization and clinical outcomes, and understand the effect these conditions have on the health-care system. This article describes the results of a pilot program that supported the development of the infrastructure and data collection methods for a state-based surveillance system for selected hemoglobinopathies. Methods The system was designed to identify and gather information on all people living with a hemoglobinopathy diagnosis (sickle cell diseases or thalassemias) in the participating states during 2004–2008. Novel, three-level case definitions were developed, and multiple data sets were used to collect information. Results In total, 31,144 individuals who had a hemoglobinopathy diagnosis during the study period were identified in California; 39,633 in Florida; 20,815 in Georgia; 12,680 in Michigan; 34,853 in New York, and 8,696 in North Carolina. Conclusion This approach provides a possible model for the development of state-based hemoglobinopathy surveillance systems.

Objective To investigate the rate of transient thyroid deficiency and treatment compliance among cases with congenital hypothyroidism diagnosed and followed-up after age 3 years by newborn screening (NBS). Study design Cases detected by Michigan NBS between October 1, 2003, and December 31, 2007, and followed-up after age 3 years were included. The X2 and Fisher exact tests were used to test differences among followed and lost cases. Logistic regression models were used to investigate predictors of treatment cessation. Results Roughly 45% of eligible cases were lost to follow-up, and disease state (transient or permanent congenital hypothyroidism) could not be determined for 12 cases (7.9%). Of the 72 followed cases, 34 (47%) were considered permanent congenital hypothyroidism based on thyroid imaging findings (n = 7) or an increase in medication dosage over time (n = 27). One-quarter of followed cases with congenital hypothyroidism were no longer being treated, and of these, just over 83% stopped treatment without medical supervision. Of 23 cases that underwent a medically supervised trial without thyroid hormone medication, treatment was reinstated in 20. Laboratory confirmation of euthyroidism was available for 6 of 18 cases clinically deemed transient. After adjustment, black race was the strongest predictor of treatment cessation (OR, 9.86; 95% CI, 1.82–53.31). Treatment cessation was also more common among low birth weight infants and those admitted to the neonatal intensive care unit at birth. Conclusion We recommend that NBS programs include long-term follow-up through at least age 3 years to determine treatment compliance and disease permanence. Further research is needed to determine ideal follow-up program operations and reassessment methods for congenital hypothyroidism disease permanence. Guidelines that provide evidence-based reassessment methods would be beneficial for the healthcare providers of children with congenital hypothyroidism.

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Growth factors play an important role in the regulation of cell growth, division and differentiation. In this study the distribution and regulation of insulin-like growth factor-I (IGF-I) in the continuously erupting rat incisor was determined by immunohistochemistry. Results were evaluated both visually and with a computer-based image analysis system. The distribution and intensity of IGF-I immunoreactivity varied with developmental stage of the rat incisor. Strong IGF-I immunoreactivity was observed in differentiating odontoblasts and ameloblasts. The most intense immunoreactivity was observed in secretory ameloblasts, secretory odontoblasts and in maturation ameloblasts. Staining was weak or absent in post-secretory ameloblasts but persisted in post-secretory odontoblasts. Weak to moderate immunoreactivity was also seen in cells of the stratum intermedium and in the reduced enamel epithelium. Surrounding alveolar bone showed strong IGF-I immunoreactivity in osteoblasts and in the stratum basale and stratum spinosum of the adjacent labial gingival epithelium. In order to assess the role of GH in IGF-I expression, GH (65 micrograms/100 g bw) was administered for six days to dwarf GH deficient rats, producing a significant increase in body weight (P < 0.01). Measurements at different stages of odontogenesis showed that the staining intensity of secretory ameloblasts (P < 0.01) and maturation ameloblasts (P < 0.001) was significantly different between untreated and treated animals. These results indicate that IGF-I is present in cell populations of the enamel organ of the rat incisor found previously to exhibit growth hormone receptors, and that expression of IGF is GH dependent.(ABSTRACT TRUNCATED AT 250 WORDS)