Fogorvosi szemle, 2007 (100. évfolyam, 1-6. szám)

2007-10-01 / 5. szám

FOGORVOSI SZEMLE ■ 100. évf. 5. sz. 2007. 266-272.

Semmelweis University, Department of Oral Biology, Budapest' Semmelweis University, Department of Periodontology, Budapest" Semmelweis University, Department of Pediatric Dentistry and Orthodontics, Budapest*“ Semmelweis University, Department of Prosthodontics, Budapest”“

Gene polymorphisms in periodontitis and hypodontia: methodological basis of investigations

GABRIELLA ÓVÁRI', DR. BÁLINT MOLNÁR“', DR. ILDIKÓ TARJÁN“*, DR. PÉTER HERMANN““,

DR. ISTVÁN GERA”, DR. GÁBOR VARGA'

An increasing number of evidence supports the assumption that genetic factors have crucial role in the development of periodontitis and hypodontia. The strategic purpose of the authors is to identify the genetic background of these disorders and to map the gene polymorphisms involved in their development. As a first step of an experimental series, we aimed to set and optimize multiple individual gene polymorphism identification methods by the combination of polymerase chain reaction and restriction fragment length polymorphism analysis methods. We have successfully optimized eight single nucleotide polymorphism procedures that are potentially involved in periodontitis (IL-1 a -889, IL-1 ß -511, IL-1 ß +3954, IL-6 -174, IL-10 -1082, TLR-4 -299, TLR-4 -399, TNF-a -308), and another two that might be related to the appearance of hypodontia (PAX9 -1032, PAX9 -912). Besides the dominant allele, we also observed the presence of the rare allele in each polymorphism although at present we have a small sample number. These preliminary studies provide evidence for the feasibility of further investigations with large sample numbers comparing control and patient groups. These studies may lead to the development of new diagnostic strategies and provide novel tools for the early recognition of genetic predisposition and the primary control of the diseases. Furthermore, they project future therapeutic avenues for gene therapy in the cure and prevention of oral disorders.

Key words: gene polymorphism, periodontitis, hypodontia, cytokines, PAX9, SNP

Introduction

The human genome project was born to decode the genetic information system in the human organism. In 2002, when the project was practically completed, human genetics turned into a new direction: to study the variability of the genes coding proteins, the so called genetic polymorphisms [1]. Single Nucleotide Polymorphism (SNP) appears when one nucleotide is changed in the genome (for example the GCCTA sequence changes into GCTTA). This change is regarded as an SNP if it appears in at least 1% of the population [1], The summation of such minor variations greatly affects the expression and function of the coded proteins. The purpose of the authors is to study the genetic background of two frequent dental disorders, periodontitis and hypodontia, and to map the gene polymorphisms that are potentially involved in their development.

Nowadays gingival and periodontal diseases can be regarded as endemic since more than 50% of the population suffers from gingivitis while almost 20% can be diagnosed with periodontitis. In the 1960s classical epidemiological and clinical studies explained the onset of periodontitis as a consequence of poor oral hygiene and the presence of dental plaque. At that time no other factors were regarded as ethological factors besides plaque. By now it is clear that chronic periodontitis is actually a multifactor disease, and also, the dental bacterial film is important but not the only factor in the development of destructive periodontitis [2], Modern epidemiological, clinical and experimental investigations provided evidence for the role of numerous risk factors in the development of the disease. Among these, besides poor oral hygiene, plaque retention factors supporting plaque accumulation, occlusal overload, smoking, emotional stress, age and gender, diseases interfering with the immune system, nutritional deficiency related diseases, osteoporosis and previously manifested periodontitis, genetic factors and even ethnic background also appear to be important

[3] [2], But our present knowledge is still very limited about the genes that are involved in the pathomechanism of the development of periodontitis through their allele variations [1] [4] [5].

Among congenital dental disorders hypodontia is the most frequent, affecting approximately 20% of the population worldwide [6]. By our definition hypodontia means one or more missing teeth, while the more pronounced anomaly, oligodontia is characterized by six or more missing teeth. Most frequently the third molars are affected. Excluding wisdom teeth, the incidence of hypodontia was variably reported to be 2 to 54% of the