P. C. Trevilatto

Absence of mutations in the homeodomain of the MSX1 gene in patients with hypodontia

Hypodontia, the congenital absence of one or a few permanent teeth, is one of the most frequent alterations of the human dentition. Although hypodontia does not represent a public health problem, it may cause both speech and masticatory dysfunction and esthetic problems. A missense mutation in the homeodomain of MSX1 gene has been associated with hypodontia of second premolars and third molars in humans. However, another study excluded this gene as causative locus for hypodontia of incisors and premolars. To further investigate the role of the MSX1 gene in human hypodontia, we analyzed the homeobox region of the MSX1 gene in 20 individuals with different patterns of familial or isolated hypodontia. The direct sequencing of PCR products did not show any polymorphisms or mutations in the human MSX1 gene. Our results indicate that inactivation of MSX1 gene in humans must have a highly selective effect on dentition, and other genes must be involved in the cause of hypodontia in humans.

Influence of MMP-8 promoter polymorphism in early osseointegrated implant failure.

ObjectiveDental implants consist in the treatment of choice to replace tooth loss. The knowledge that implant loss tends to cluster in subsets of individuals may indicate that host immuneinflammatory response is influenced by genetic factors. In fact, genetic polymorphisms influence the osseointegration process. The objective of this study was investigate the possible relationship between C-799T polymorphism in matrix metalloproteinase 8 (MMP-8) gene and early implant failure in nonsmoker patients.Methods and materialsSubjects were divided into two groups: control group (100 patients with one or more healthy implants) and test group (80 patients that had suffered one or more early implant failures). Genomic DNA from oral mucosa was amplified by PCR and analyzed by restriction endonucleases. The significance of the differences in observed frequencies of polymorphisms was assessed by Chi-square.ResultsStatistical analysis shows that in the MMP-8 gene, the T allele in 76.25% in the test group and the T/T genotype, 63.75% in the same group, may predispose to early loss of implants osseointegrated.ConclusionThese results suggest that polymorphism in the promoter region of MMP-8 gene is associated with early implant failure. This polymorphism can be a genetic marker to risk of implant loss.Clinical relevanceThe determination of this genetic pattern in osseointegration would enable the identification of individuals at higher risk to loss implant. Thus, genetic markers will be identified, contributing to an appropriate preoperative selection and preparation of strategies for prevention and therapy individualized to modulate the genetic markers and increase the success rate of treatments.

Immunochemical analysis of laminin during postnatal development of the rat submandibular gland

Anti-laminin serum was used to investigate distribution patterns and chain composition of laminin during postnatal development of rat submandibular gland. Immunohistochemical analysis showed that in glands of newborn rats laminin was not uniformly present around growing acini. Staining was frequently weak or absent in clefts formed between adjacent cells. This irregular staining pattern decreased progressively over the subsequent periods, and in 30-day-old animals immunoreactivity was observed only at the periphery of glands. Immunoblot analysis showed that laminin was composed of bands corresponding to the alpha 1, beta 1 and gamma 1 polypeptides. The correlation between the pattern of laminin expression and gland maturation suggests a role of laminin in the functional maturation of acinar cells.