Early onset periodontitis: a comparison and evaluation of two proposed modes of inheritance

Orthodontic Management in Aggressive Periodontitis

Aggressive periodontitis is a type of periodontitis with early onset and rapid progression and mostly affecting young adults who occupy a large percentage of orthodontic patients. The role of the orthodontist is important in screening the disease, making a provisional diagnosis, and referring it to a periodontist for immediate treatment. The orthodontist should be aware of the disease not only before starting the appliance therapy, but also during and after the active mechanotherapy. The orthodontic treatment plan, biomechanics, and appliance system may need to be modified to deal with the teeth having reduced periodontal support. With proper force application and oral hygiene maintenance, orthodontic tooth movement is possible without any deleterious effect in the tooth with reduced bone support. With proper motivation and interdisciplinary approach, orthodontic treatment is possible in patients with controlled aggressive periodontitis.

Interleukin-1α -899 (+4845) C→T polymorphism is not associated with aggressive periodontitis susceptibility: A meta-analysis based on 19 case-control studies

A number of published studies investigated the association between interleukin-1α (IL-1α) −899 (+4845) C→T polymorphism and susceptibility to aggressive periodontitis (AgP). However, the results from different studies are controversial. This study was conducted to further investigate the association between IL-1α −899 (+4845) C→T polymorphism and AgP using a meta-analysis. A search was conducted through PubMed up to May 1, 2013 and a total of 19 relevant case-control studies were identified. The results of this meta-analysis demonstrated that IL-1α −899 (+4845) C→T polymorphism is not associated with susceptibility to AgP under allele T vs. C [odds ratio (OR)=1.00, 95% confidence interval (CI): 0.88–1.14, P=0.98; I²=28.86%] or allele A vs. C comparison (OR=0.99, 95% CI: 0.85–1.14, P=0.85; I²=33.66%). The subgroup analyses based on ethnicity, source of controls and Hardy-Weinberg equilibrium (HWE) also revealed no such association. There existed a weak publication bias (Egger’s test P=0.02). In conclusion, based on the currently available evidence, there is no association between IL-1α −899 (+4845) C→T polymorphism and susceptibility to AgP.

Do X-linked diseases affect periodontal health?

Genetic factors play an important etiologic role in destructive periodontal diseases. There have been reports that sex chromosomes, especially disorders associated with the X chromosome, affect periodontal health. Although numerous X-linked diseases have been reported to be associated with various periodontal diseases, the association of gingivitis and/or periodontitis with these genetic syndromes should be considered tenuous and raises the question of whether the periodontal manifestation truly arises from an underlying X-linked genetic etiology. A brief overview of genetics in relation to sex chromosomes and putative X-linked genetic periodontal diseases is given.

Aggressive periodontitis is likely influenced by a few small effect genes

AIM

To evaluate the inheritance mode of aggressive periodontitis in a collection of families with a similar geographic origin.

MATERIALS AND METHODS

Segregation analysis was performed in pedigree data from 74 families by the use of the SEGREG program of SAGE v.5.4.2. Homogeneous no transmission, homogeneous Mendelian transmission, homogeneous general transmission, semi-general transmission and heterogeneous general transmission models were tested assuming the prevalence of aggressive periodontitis as 1% and no deviations from Hardy-Weinberg equilibrium. The parameters of the model were estimated by the method of maximum likelihood, which provides the overall ln (likelihood), -2ln and the AIC (Akaike's score) for each model. The likelihood ratio test (LRT) was used to compare each model against a fully general model (p>0.05).

RESULTS

The most parsimonious mode of inheritance was the semi-general transmission model that allows the heterozygote transmission probability to vary.

CONCLUSION

This result provides strong support for the hypothesis that genetic factors play a role in aggressive periodontitis and that a few loci, each with relatively small effects, contribute to aggressive periodontitis, with or without interaction with environmental factors.

Polymorphisms in the interleukin-1 (IL1) gene cluster are not associated with aggressive periodontitis in a large Caucasian population

Polymorphisms in the interleukin-1 (IL1) gene have been suggested to influence transcription of IL1A (interleukin-1alpha) and IL1B (interleukin-1beta) and thereby the pathophysiology of periodontitis. This case-control association study on 415 northern European Caucasian patients with aggressive periodontitis (AgP) and 874 healthy controls was conducted to examine 10 single-nucleotide polymorphisms (SNPs) in the genes of the IL1 cluster for association with IL1A, IL1B, CKAP2L (cytoskeleton-associated protein 2-like), and IL1RN (IL-1 receptor antagonist). The results do not support an association between variants in the IL1 gene cluster and AgP. This case-control study had at least 95% power to detect genuine associations with variants carrying relative risks of at least 1.5 for heterozygous carriers and 2.25 for homozygous carriers. Previous reports of an association between IL1 promoter SNPs and periodontitis might reflect subpopulation effects and have to be interpreted with care.

A case-control study on the association of human leukocyte antigen-A*9 and -B*15 alleles with generalized aggressive periodontitis in an Indian population

BACKGROUND

The genes encoding the human leukocyte antigens (HLAs; major histocompatibility complex [MHC]) have been considered candidate markers for periodontitis because they are involved in regulating immune responses. Several studies have examined this association, and despite the inconclusive results, the antigens HLA-A9 and HLA-B15 have been found to be consistently associated with the destructive forms of periodontitis in many populations. Ethnic factors are considered to be a major variable for evaluating the predisposition to the disease. The purpose of the present study was to: 1) assess the association of HLA-A*9 and HLA-B*15 with generalized aggressive periodontitis (GAgP) and 2) evaluate the role of these genetic risk factors in influencing the severity of GAgP in a South Indian population.

METHODS

Forty GAgP patients (cases) and 80 periodontally and systemically healthy subjects (controls) participated in this study. HLA-A*9 and HLA-B*15 typing was carried out using the polymerase chain reaction with sequence specific primers (PCR-SSP)-based molecular method.

RESULTS

HLA-B*15 was a significant risk factor for GAgP and was positively correlated with the disease severity, whereas HLA-A*9 had no association with the disease. The haplotype of HLA-A*9:B*15 did not impart any additional risk for GAgP compared to that imparted by HLA-B*15 alone.

CONCLUSIONS

To our knowledge, this is the first report on HLA-B*15 association with GAgP in an Indian population. The finding of HLA-B*15 as a risk factor may have potential use in the future management of GAgP. The precise disease-causing mechanism of this HLA disease association and whether this association is "causal" or "casual" need to be evaluated further.

Periodontal status among relatives of aggressive periodontitis patients and reliability of family history report

OBJECTIVES

To assess the periodontal status of relatives of Aggressive Periodontitis (AgP) patients, and to evaluate the reliability of the family history report as provided by the proband.

MATERIAL AND METHODS

Data from 54 AgP patients were gathered along with a family history report for each of their relatives. Only 27 patients (probands) had relatives willing to be examined. This yielded a total of 61 relatives from whom the periodontal status was obtained. The family history report for each examined relative was compared with the periodontal diagnosis made at examination to assess reliability.

RESULTS

Eight percentage of the examined relatives, aged between 12-76, were diagnosed with AgP, while chronic periodontitis was present in 39%, gingivitis in 38% and 15% were healthy. If the report provided by the proband was positive, the likelihood of finding any type of periodontitis in that relative was 85.7%, whereas if the report was negative the likelihood of the absence of periodontitis was 70.6%.

CONCLUSION

The percentage of examined relatives who were affected with AgP (8%), although lower than percentages reported in other AgP family studies, was still higher than the prevalence of the condition in random populations. Reliability of periodontal family history was considered good and more reliable when it was positive.

Quantitative Measures of Aggressive Periodontitis Show Substantial Heritability and Consistency With Traditional Diagnoses

BACKGROUND

Aggressive periodontitis (AgP) research nearly always classifies subjects into traditional discrete categories of localized or generalized, based upon degree of attachment loss (AL) and types of affected teeth. Since AL is continuous and quantitative, however, useful information is lost. We developed quantitative measures of AgP, compared these to traditional methods, and estimated heritabilities in families.

METHODS

We examined 237 healthy, 169 localized AgP, and 204 generalized AgP subjects. We used the site of maximum AL of each tooth to calculate means for each subject for different groups of teeth. We also applied principal components analysis (PCA) to condense variation among 28 teeth into three orthogonal (uncorrelated) variables. We used discriminant function analysis (DFA) to evaluate how well the quantitative measures match with traditional classifications. Quantitative trait heritabilities were estimated by variance components.

RESULTS

PCA clustered first molars, incisors, and the other teeth into three groups. DFA showed that quantitative measures classified subjects consistent with traditional methods (87% to 94% agreement). Heritabilities ranged from 13.7% (P = 0.10) to 30.0% (P = 0.008) for quantitative measures, with highest values obtained for first molars. A combination of the principal component variables most heavily weighted on first molars and incisors gave the best model of disease susceptibility, with good separation of healthy versus diseased subjects, independent of disease extent or severity.

CONCLUSIONS

Quantitative measures may provide improved precision and power for many kinds of periodontal research. Our finding of significant heritability supports their use in gene mapping studies of AgP susceptibility.

Genes and gene polymorphisms associated with periodontal disease

The scientific literature during the last ten years has seen an exponential increase in the number of reports claiming links for genetic polymorphisms with a variety of medical diseases, particularly chronic immune and inflammatory conditions. Recently, periodontal research has contributed to this growth area. This new research has coincided with an increased understanding of the genome which, in turn, has permitted the functional interrelationships of gene products with each other and with environmental agents to be understood. As a result of this knowledge explosion, it is evident that there is a genetic basis for most diseases, including periodontitis. This realization has fostered the idea that if we can understand the genetic basis of diseases, genetic tests to assess disease risk and to develop etiology-based treatments will soon be reality. Consequently, there has been great interest in identifying allelic variants of genes that can be used to assess disease risk for periodontal diseases. Reports of genetic polymorphisms associated with periodontal disease are increasing, but the limitations of such studies are not widely appreciated. While there have been dramatic successes in the identification of mutations responsible for rare genetic conditions, few genetic polymorphisms reported for complex genetic diseases have been demonstrated to be clinically valid, and fewer have been shown to have clinical utility. Although geneticists warn clinicians on the over-enthusiastic use and interpretation of their studies, there continues to be a disparity between the geneticists and the clinicians in the emphasis placed on genes and genetic polymorphism associations. This review critically reviews genetic associations claimed for periodontal disease. It reveals that, despite major advances in the awareness of genetic risk factors for periodontal disease (with the exception of periodontitis associated with certain monogenetic conditions), we are still some way from determining the genetic basis of both aggressive and chronic periodontitis. We have, however, gained considerable insight into the hereditary pattern for aggressive periodontitis. Related to our understanding that it is autosomal-dominant with reduced penetrance comes a major clinically relevant insight into the risk assessment and screening for this disease, in that we appreciate that parents, offspring, and siblings of patients affected with aggressive periodontitis have a 50% risk of this disease also. Nevertheless, we must exercise caution and proper scientific method in the pursuit of clinically valid and useful genetic diagnostic tests for chronic and aggressive periodontitis. We must plan our research using plausible biological arguments and carefully avoid the numerous bias and misinterpretation pitfalls inherent in researching genetic associations with disease.

Distribution of Interleukin-1β+3954and IL-1α–889Genetic Variations in a Thai Population Group

BACKGROUND

The severe form of chronic periodontitis (CP) has been reported to be strongly associated with the presence of allele 2 of composite IL-1beta(+3954) and IL-1alpha(-889) genetic polymorphisms (genotype positive). However, other studies have reported conflicting findings, not only on the association between the composite IL-1 gene polymorphisms and CP, but also the link between IL-1 gene polymorphisms and aggressive periodontitis (AgP). These might have resulted from differences in ethnic background and disease entities. The aim of this study was to determine the distribution of IL-1beta(+3954) and IL-1alpha(-889) genetic polymorphisms in a group of Thai subjects based on their periodontal status, including CP, AgP, and healthy groups.

METHODS

A total of 123 Thai subjects were clinically and radiographically assessed for their periodontal status. Blood samples were collected by fingerstick and adsorbed onto filter paper. The IL-1beta(+3954) and IL-1alpha(-889) genotypes were performed by polymerase chain reaction, digested with restriction enzymes, and separated by gel electrophoresis.

RESULTS

The distribution of allele 1 homozygous genotype was 97.6% and 84.6% for IL-1beta(+3954) and IL-1alpha(-889), respectively. No allele 2 homozygous genotype was detected in either of these two gene loci. Only 1.6% (2 out of 123) of the subjects were genotype positive, which was too low to determine the association between the composite genotype of IL-1beta(+3954) and IL-1alpha(-889) and severe forms of periodontal disease.

CONCLUSION

Genetic polymorphism of IL-1 genes in these two loci may not be useful in predicting the severity of periodontal disease in the Thai ethnic group.

HLA-A, B, Cw, DRB1, DRB3/4/5, DQB1 in German patients suffering from rapidly progressive periodontitis (RPP) and adult periodontitis (AP)

BACKGROUND/AIM

There is growing indication that differences in host response determine susceptibility and resistance to periodontal disease. Particularly, the effect of histocompatibility antigens (HLA) on early onset periodontitis (EOP) has been studied. As most of the results are not conclusive and to date no report has been done on German patients, the aim of this study was to investigate the distribution of HLA alleles in a group of 50 German RPP patients and 102 German AP patients and to compare them to 102 control probands without periodontitis.

METHODS

Diagnosis was established according to standardised clinical criteria. HLA typing was performed using serologic and molecular biologic (PCR-SSP) techniques.

RESULTS

Compared to the controls, RPP patients had a significantly higher frequency of HLA-DRB1*13 and a significantly lower frequency of HLA-DRBblank*(non-DRB3/4/5). AP patients showed a significantly increased occurrence of HLA-B*14 and -Cw*08 as well as a significantly decreased frequency of HLA-A*03. In both patient groups HLA-A*11 and -A*29 had an increased frequency and HLA-A*31 and -A*30/31 were decreased. These differences were statistical significant in the whole patient group (RPP + AP).

CONCLUSIONS

Based on modern DNA techniques the present study shows an association of HLA to both RPP and AP. Certain HLA alleles seem to be associated with susceptibility or resistance to periodontitis in general. However, before this knowledge can be used for differential diagnosis or prognosis, further investigations are necessary.

Gender differences in HLA phenotype frequencies found in German patients with generalized aggressive periodontitis and chronic periodontitis

HLA antigens have been considered as risk factors for periodontitis. Differences in prevalence and in the extent of attachment loss between males and females have suggested that gender-dependent HLA deviations could play a role in individual predisposition to periodontitis. The aim of the present study was therefore to investigate the incidence of gender-dependent HLA associations in 50 patients with generalized aggressive periodontitis (AP) and 102 patients with chronic periodontitis (CP) in comparison to 102 probands without any attachment loss caused by periodontitis. HLA typing was carried out using a microlymphocytotoxic test and a polymerase chain reaction with sequence-specific primers (PCR-SSP). Female AP patients showed an increase in the frequency of HLA-A*68/69 and a decrease in the frequency of DRBblank* (non-DRB3/4/5*) and DQB1*05-positive probands. Only in female CP patients was HLA-DQB1*0303 absent, whereas HLA-DQB1*06 homozygosity increased significantly. With regard to the (AP + CP) periodontitis group as a whole, the increased frequency of HLA-DQB1*06 homozygosity in females was similar to the findings obtained in the AP group. Evidently, gender is a confounding variable, which should be considered in further studies of HLA and periodontitis.

Relationship between vitamin D receptor gene polymorphism and periodontitis

Recent studies have shown that vitamin D receptor (VDR) gene polymorphism had regulatory effects on bone mineral density (BMD) and bone turnover. The VDR gene has also been indicated as a candidate gene for the susceptibility of osteoporosis. However, it is unclear whether VDR genotypes could be associated with alveolar bone loss of patients with periodontitis, or whether vitamin D receptor gene could be a candidate gene for susceptibility to periodontitis. The purpose of this study was to answer these two questions.

METHODS

Twenty-four cases of adult periodontitis (AP), 37 cases of early onset periodontitis (EOP) and 39 healthy controls were recruited for the study. Individual samples of venous blood and DNA were obtained from each subject. Genotypes of the TaqI VDR gene were determined by PCR and TaqI restriction endonuclease digestion.

RESULTS

One out of 24 AP patients, nine out of 37 EOP patients and two out of 39 healthy controls were detected with Tt genotype, while the rest had the TT genotype. The detected frequency of Tt genotype was significantly higher in EOP patients (24.3%) than in AP patients (4.2%) and healthy controls (5.1%). The frequency of t allele was also significantly higher in EOP patients. There was no statistical difference in the distribution of TaqI VDR genotypes between AP patients and healthy controls. The study suggests that Tt genotype might be a risk indicator for the susceptibility to EOP. Carriage of the allele (t) of the TaqI VDR gene may increase the risk of developing EOP.

Clinical and genetic analysis of a large North European Caucasian family affected by early-onset periodontitis

Genetic studies of early-onset periodontitis (EOP) are hampered by several factors. These include delayed onset of the trait, an upper age limit of expression of the disease, and lack of phenotypic information for edentulous family members. Segregation analyses of families with EOP support a major locus hypothesis but fail to define clearly the criteria used for diagnosis of the relatives. Confirmation of a proposed mode of inheritance and the identification of risk genes is awaited by means of family linkage studies. It is suggested that a system can be developed for the current and retrospective diagnosis of relatives of EOP probands. In addition, it is hypothesized that the large family presented here is suitable for a linkage study. Relatives of the proband who were unavailable for a full periodontal examination, were edentulous, or were deceased, were diagnosed by means of documented clinical evidence of periodontal disease or from reported case histories. Segregation analysis was performed. Analysis of the power of the pedigree to detect linkage was carried out by means of the SIMLINK program. Three different categories were defined according to the reliability of diagnosis of EOP. Segregation analysis indicated either autosomal-dominant or X-linked-dominant inheritance in this family. The simulations showed lod scores above 3.0 for all locations of the disease gene, and for each category of diagnosis. In conclusion, a method has been developed which can be used for the diagnosis of relatives of EOP probands when ideal clinical data are unavailable. The simulations suggest that this family is suitable for a genetic linkage study with the aim of identifying the location of one or more susceptibility genes.

Early-onset periodontitis

In 1993, the 1st European Workshop on Periodontology explicitly recognized that there was insufficient knowledge to differentiate truly different forms of periodontal disease from differences in the presentation/severity of the same disease. In spite of recent progress in our understanding of periodontal diseases, the issue is far from having been resolved. Classification of periodontal diseases, therefore, remains based upon the definition of specific clinical syndromes. Early-onset periodontitis (EOP) is one such syndrome and comprises a group of pathological conditions leading to loss of periodontal tissues early in life. The notion that classifies periodontitis syndromes as "early-onset" or "adult" is primarily epidemiological in nature and is based on the observation that periodontitis is rather infrequent in children and young adults. Nevertheless, considerable epidemiological evidence indicates that periodontitis does affect children and young adults to a level of severity that may lead to premature exfoliation of primary and/or permanent teeth. Clinical presentation of periodontitis early in the life of an individual is thought to indicate that the etiologic agents have been able to cause considerable tissue damage over a relatively short period of time. It also implies either infection with highly virulent bacteria and/or a highly susceptible subject. The purpose of this review is to discuss the criteria generally utilized to classify EOP, provide the rationale to designate EOP as a distinct disease entity, and to review the evidence justifying a subclassification into particular subgroups of EOP.

Analysis of genetic polymorphisms at the interleukin-10 and tumour necrosis factor loci in early-onset periodontitis

Early onset periodontitis (EOP) is considered to have a substantial genetic basis, although the gene or genes involved have not been elucidated. The aim of the present study was to investigate possible links between generalized EOP (GEOP) and genes regulating expression of the cytokines tumour necrosis factor (TNF) and interleukin-10 (IL-10). Microsatellite marker DNA sequences corresponding to phenotypic variations in cytokine response were analysed. Genotypic variations in cytokine response have been shown in vitro for TNF and IL-10, and specific alleles are implicated in diseases such as systemic lupus erythmatosus (SLE) and rheumatoid arthritis (RA). Two microsatellites at the IL-10 locus, IL10.R and IL10.G, and 1 microsatellite at the TNF locus, TNFa, were typed for 77 GEOP patients in the West of Scotland. Due to the highly polymorphic nature of the microsatellite loci, a statistical comparison with ethnically matched healthy controls (TNFa, n = 91, IL10.R, n = 94, IL10.G, n = 102) was conducted using a Monte Carlo simulation for each marker. No significant differences were observed for any of the 3 markers, although there were possible indications of trends similar to those observed in SLE for the IL10.G marker. In conclusion, no links were found between GEOP and microsatellites at TNFa, IL10.R or IL10.G loci.

The pathogenesis of periodontal diseases

This informational paper was prepared by the Research, Science, and Therapy Committee of The American Academy of Periodontology, and is intended for the information of the dental profession. The purpose of the paper is to provide an overview of current knowledge relating to the pathogenesis of periodontal diseases. The paper will review biological processes thought to provide protection against periodontal infections. It will further discuss the mechanisms thought to be responsible for both overcoming and subverting such protective mechanisms and those that lead to destruction of periodontal tissues. Since an understanding of pathogenic mechanisms of disease is one foundation upon which new diagnostic and therapeutic modalities are based, the practitioner can use this information to help make decisions regarding the appropriate application of such new modalities in patient care settings.

Linkage disequilibrium of interleukin-1 genetic polymorphisms with early-onset periodontitis

BACKGROUND

Genetic polymorphisms at interleukin (IL)-1alpha and IL-1beta were recently suggested to be associated with severity of adult periodontitis. We evaluated whether these polymorphisms might also be associated with early-onset periodontitis (EOP) in 28 African American families and 7 Caucasian American families with 2 or more affected members.

METHODS

Genomic DNA from peripheral blood was amplified, followed by restriction endonuclease digestion and acrylamide gel electrophoresis to distinguish alleles of different fragment sizes. Genetic epidemiological methods suitable for family data were used that are robust to false-positive findings due to mismatching of cases and controls or mixed subpopulations of different ethnic or geographic origin. The 2 major EOP subtypes, localized juvenile periodontitis (LJP), and generalized early-onset periodontitis (G-EOP, encompassing rapidly progressive periodontitis and generalized juvenile periodontitis), were analyzed both separately and together.

RESULTS

We obtained highly significant evidence of linkage disequilibrium for both African American and Caucasian G-EOP subjects. A similar trend was noted for LJP. The IL- alleles associated with high risk of EOP had been suggested previously to be correlated with low risk for severe adult periodontitis. Disequilibrium with G-EOP was equally strong for smoking and non-smoking subjects. IL-1alpha and IL-1beta polymorphisms were in strong disequilibrium with each other in Caucasians, but not in African Americans. Haplotype analyses evaluating both polymorphisms simultaneously indicated that the IL-1beta variant is likely to be most important for EOP risk. Sibpair linkage analyses, by contrast, provided only marginal support for a gene of very major effect on EOP risk attributable to these IL-1 polymorphisms.

CONCLUSIONS

Recent theoretical analyses indicate that our findings are most consistent with an interpretation of EOP as a complex, oligogenic disorder, with IL-1 genetic variation contributing an important but not exclusive influence on disease risk.

Early-onset periodontitis associated with Down's syndrome--clinical interventional study

Individuals with Down's syndrome (DS) have an increased prevalence of periodontal disease compared with otherwise normal, age-matched control groups and other mentally handicapped patients of similar age distribution. The exaggerated immune-inflammatory response of the tissues cannot be explained by poor oral hygiene alone and might be the result of an impaired cell-mediated and humoral immunity and a deficient phagocytic system. As far as the progression and severity of destruction, the oral manifestations of DS patients are consistent with the juvenile periodontitis (JP) disease pattern. The purpose of the present study was 1) to assess the periodontal clinical and microbiological status of 10 DS patients aged 20 to 31 years (mean: 26.3 years) relative to that of 11 patients with cerebral palsy (CP) aged 23 to 53 years (mean: 36 years) without defective immunological functions, and 2) to determine the effect of supragingival plaque control and oral hygiene instruction in these patient groups. Subsequent to the initial examination and a professional tooth cleaning program, clinical and microbiological parameters were monitored over a period of 12 weeks. The clinical examination included the recording of plaque index (P1), gingival index (GI), probing depth (PD), and clinical attachment level (CAL). Subgingival plaque samples were always obtained from the same pocket with the highest disease activity (deepest bleeding site at baseline examination) in each subject for a morphotype analysis by dark field microscopy and for identification and quantitation of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Eikenella corrodens, Bacteroides forsythus, Fusobacterium nucleatum, Treponema denticola, and Campylobacter rectus by DNA probes. The results of the baseline examinations demonstrated that DS patients and patients with cerebral palsy had inflamed gingiva associated with a high amount of plaque. The mean probing depth and percentage of sites with probing depth> 4 mm corresponded to age and poor oral hygiene in CP patients. Deep pockets in DS patients demonstrated a high prevalence of periodontal disease compared with age-matched children with mental retardation and non-handicapped patients. Regarding the young age of onset, the severe destruction of periodontal tissues and pathogenesis of periodontitis in DS patients are consistent with the juvenile periodontitis disease pattern. The missing clinical benefit and alteration of the subgingival flora following supragingival plaque control in DS patients underlined the alteration in the immunological response.

Risk assessment for periodontal diseases

Assessment of risk for periodontitis is still in its infancy. Nevertheless, a sufficient amount of dependable information exists to begin using risk assessment in the day to day practice of dentistry. The purpose of this paper is to summarise existing information about risks for periodontitis in a manner that is useful to practitioners. Risks for moderate to severe periodontitis that have been identified include cigarette smoking, advancing age, diabetes mellitus and certain other systemic conditions. These include, osteoporosis and HIV infection and conditions such as irradiation and immunosuppressive drugs that interfere with normal host defences, specific pathogenic bacteria in the subgingival flora, microbial deposits and poor oral hygiene status, bleeding on probing, previous disease experience and severity, and inheritance. Some risks such as pathogenic bacteria in the subgingival flora are strongly linked to causation of the disease while others such as bleeding on probing may indicate enhanced risk for future disease but are not known to be involved in causation and still others such as advancing age may be background factors that enhance susceptibility. While some risks such as cigarette smoking can be modified to lower the level of risk, others such as ageing are immutable and cannot be modified but need to be considered in overall risk assessment. A goal of periodontal diagnosis, treatment planning and therapy is to lower risk for future periodontal deterioration to the maximal extent. One approach to achieving this goal is described.

Smoking and its effects on early-onset periodontitis

The findings of a recent study show that smoking was more prevalent in a group of patients with generalized early-onset periodontitis and adult periodontitis than in patients with localized juvenile periodontitis or healthy periodontium. In patients with generalized early-onset periodontitis, smoking had a significant effect on periodontal attachment loss; these patients had significantly more teeth with affected sites and a greater mean loss of attachment than patients who did not smoke. Thus, the risk of smoking could greatly accelerate tooth loss in this relatively young group of individuals who are already at high risk for progressive periodontal attachment loss.

Evidence for autosomal dominant inheritance and race-specific heterogeneity in early-onset periodontitis

Early-onset periodontitis (EOP) refers to a group of severe periodontal diseases with age of onset near puberty that are characterized by rapid destruction of the tissues supporting the teeth in otherwise healthy individuals. Mixed model segregation analyses of 100 families, ascertained through 104 probands with EOP, were carried out to test major locus and multifactorial hypotheses for the etiology of EOP. Heterogeneity tests were used to compare the parameter estimates and conclusions obtained in Black families from those from non-Black families. The data in these families confirmed that the often-reported female preponderance of EOP appears to be an ascertainment bias. The segregation analysis results were consistent with an autosomal major locus being sufficient to explain the family patterns of EOP in the entire dataset, and also in both the Black and non-Black subsets. A dominant mode of transmission was most likely, with penetrance of about 70%. Although the etiologic conclusions were the same for Black and non-Black families, there was significant heterogeneity in parameter estimates. In particular the Black allele frequency was 0.016 versus the non-Black frequency of 0.001.

Genetic and heritable risk factors in periodontal disease

The purpose of this paper is to review current knowledge of genetic risk factors for the periodontal diseases and to present updated and additional data from the Minnesota Twin Periodontal Study. Family studies suggest that susceptibility to the early onset forms of disease, particularly prepubertal and juvenile periodontitis, is, at least in part, influenced by host genotype. Inherited phagocytic cell deficiencies appear to confer risk for prepubertal periodontitis. The prevalence and distribution of juvenile periodontitis in affected families are most consistent with an autosomal recessive mode of inheritance. However, considerable etiologic as well as genetic heterogeneity within these clinically-defined diseases is evident. Whether or not genetic factors influence the more common adult chronic periodontitis is less clear. Although results from family studies suggest that environmental factors appear to be the major determinants of variance in adult periodontitis, data from our twin studies indicate that both genetic and environmental factors influence disease. Furthermore, comparisons between reared-together and reared-apart adult monozygous twins indicate that early family environment has no appreciable influence on probing depth and attachment loss measures in adults.

Serum immunoglobulin G subclass concentrations in periodontally healthy and diseased individuals

Patients with localized juvenile periodontitis (LJP) often have high titers of antibody reactive with the serotype-specific immunodominant carbohydrate antigen of Actinobacillus actinomycetemcomitans serotype b. The vast majority of this A. actinomycetemcomitans serotype b-specific antibody is immunoglobulin G2 (IgG2). The present study was undertaken to determine whether the overall total levels of IgG2 in the sera of LJP patients are elevated. LJP patients and nonperiodontitis (NP) controls matched for age, race (black and white), and gender were studied. Additional controls included patients with adult periodontitis (AP) and patients similar in age to LJP patients but with the more-severe, generalized form of early-onset periodontitis (SP). Sera from over 700 periodontally characterized subjects were examined by using radial immunodiffusion to quantitate IgG2 as well as IgG1, -3, and -4, which were included for comparison. Serum IgG2 levels increased with age, and this was most dramatic around puberty. Black subjects in all periodontal groups had nearly 1 mg more IgG2 per ml than their white counterparts. Serum IgG2 levels were elevated (about 30 to 40%) in LJP patients of both races compared with their age- and race-matched NP controls (P < 0.01). In contrast, SP patients and AP patients had IgG2 levels comparable to their age- and race-matched NP controls. No other IgG subclass concentration correlated with periodontal diagnosis except for IgG3, which was elevated in white LJP patients. We reason that the high levels of serum IgG2 in LJP may be helpful in localizing periodontal destruction.

Periodontal therapy in young adults with severe generalized periodontitis

This study evaluated the effect of periodontal therapy on clinical and microbiological parameters in 23 subjects with severe generalized early onset periodontitis. Therapy consisted of oral hygiene instruction and root planing and scaling, followed 3 months later by open flap debridement. Subjects were monitored for both clinical measures and levels of Actinobacillus actinomycetemcomitans and Porphyromas gingivalis as identified by indirect immunofluoresence. Clinical and microbiological evaluations were done at the start of the study, 3 months after the completion of root planing and scaling and 3 months after open flap debridement. Mean probing depth was reduced by both root planing and scaling and open flap debridement and the level of reduction demonstrated by both phases of therapy was similar to reductions found in studies that utilized subjects with chronic adult periodontitis. In contrast, reductions in attachment level due to the two phases of therapy, demonstrated in previous studies of subjects with adult periodontitis were not found in the young adult subjects with severe periodontal disease utilized in this study. Levels of A. actinomycetemcomitans were not significantly affected by root planing and scaling, but were reduced by open flap debridement. P. gingivalis was virtually eliminated by root planing and scaling, demonstrating that the two bacterial types respond differently to periodontal therapy. These changes in microbiological parameters were similar to those found in studies of localized juvenile periodontitis subjects, where surgery or antibiotics have been shown to be necessary to reduce levels of A. actinomycetemcomitans.

Reevaluation of the chromosome 4q candidate region for early onset periodontitis

Evidence of linkage (lod = 3.1, theta = 0.05) was reported previously in one large kindred (the Brandywine genetic isolate) for an autosomal dominant form of early onset periodontitis (EOP) with a protein polymorphism in the vitamin D binding protein (GC) located on chromosome 4q12-q13. To evaluate the generality of this finding, 19 unrelated families (228 individuals), each with two or more EOP affected individuals, were ascertained and sampled. A restriction fragment length polymorphism (RFLP) at the GC locus and eight other polymorphic DNA markers and two red blood cell antigens located on proximal chromosome 4q in the vicinity of the GC locus were typed. Twelve genetic models of EOP were evaluated, which varied in diagnostic classification, penetrance, and mode of disease transmission. Results for all models strongly exclude linkage between an EOP susceptibility gene and this chromosomal region assuming locus homogeneity. Our data statistically exclude (lod < or = -2.0) the possibility that more than 40% of our families are linked to this candidate region for one model tested. Linkage under heterogeneity was excluded less strongly for other models, but no significant evidence in support of linkage was obtained for any model. Our results indicate that either the previous report of linkage was a false positive, or that there are two or more unlinked forms of EOP, with the form located in 4q12-q13 being less common.

The influence of race and gender on periodontal microflora

Previous studies have demonstrated that demographic characteristics of subject populations influence both the incidence of periodontal diseases and various aspects of host responses to periodontal bacteria. In this study we analyzed the components of the subgingival microflora from individuals with adult periodontitis, early onset periodontitis, gingivitis, and periodontal health as a function of gender and race (black and white). Clinical categories were analyzed individually so that there were no differences in the clinical characteristics of the sampled sites. No significant differences were noted in the subgingival microflora between males and females. When either the first two bacterial samples from each subject or all bacterial samples taken from each subject were included in the analysis, it was found that Porphyromonas gingivalis was more significantly associated with black subjects in the adult periodontitis group. When all samples were considered in the analysis, it was found that Peptostreptococcus anaerobius was associated with black subjects in the adult periodontitis group, while Fusobacterium nucleatum was associated with white subjects in both the adult periodontitis and early onset periodontitis groups. Thus a limited number of important bacterial components of the subgingival microflora are influenced by the race and diagnosis of the subject group.

Marginal bone loss in the primary dentition of patients with juvenile periodontitis

118 patients with juvenile periodontitis (JP), diagnosed when the patients were 13-19 years old, were studied retrospectively with respect to radiographic marginal bone loss in the primary dentition, experienced when the patients were 5-12 years old. 168 other 13-19 year old patients without any signs of bone loss in the permanent teeth were used as a reference group. The JP patients were classified into 2 groups according to the number of sites with bone loss in the permanent dentition: JP group I having 1 site with bone loss (n = 45) and JP group II having > or = 2 sites with bone loss (n = 73). It was found that 35 patients (52%) of JP group II displayed 1 or more sites with bone loss in the primary dentition during the age of 5-12 years. The corresponding numbers for JP group I and the reference group were 9 (20%) and 8 (5%) respectively. These findings indicate that juvenile periodontitis, at least in some individuals, may have its onset already in the primary dentition.

Differential diagnosis in clinical trials of therapy for periodontitis

For purposes of clinical trials of therapies for periodontitis, it is recommended that population samples be identified as adult periodontitis (systemically modified or not systemically modified), early onset periodontitis (localized or juvenile, generalized or rapidly progressive, or associated with systemic disease), or necrotizing ulcerative periodontitis, avoiding overlapping criteria. Population samples of adult or early onset periodontitis modified by or associated with systemic conditions should be used in clinical trials only when the intent is to study effect on the specifically modified condition. Objective identification of the modifying systemic condition should be required for all subjects in such trials. Population samples should be homogeneous for the diagnosis, whether systemically modified or not. Refractory periodontitis, prepubertal periodontitis, and periodontitis associated with systemic disease are not recommended as useful descriptors of population samples without discrete identification of underlying systemic abnormality for all included subjects. Definition of population sample by a bacteriological or a host response feature is not recommended unless the trial is specifically aimed at that feature and the sample is homogeneous for it. All trials of efficacy should include physical or radiographic measurement of attachment level or bone height as a critical outcome variable. Results from trial in one form of periodontitis should not be applied directly to other forms.

Phenotypic assessment of early onset periodontitis in sibships

Early onset periodontitis is a group of familial diseases that are not yet clearly defined by etiologic mechanisms, although some risk factors have been recognized. The disorders include a localized form of juvenile periodontitis (JP), and a more generalized form (GP). In a family study, 39 sibships (116 individuals, aged 13-48) were evaluated for clinical indices, neutrophil chemotaxis, and serum antibodies to A. actinomycetemcomitans (Aa). Of 77 siblings, 41 were healthy at examination. In 14 sibships, all affected persons had JP; 14 other sibships had all affected individuals with GP; and 11 had at least one sib with each form. For probands with decreased chemotaxis, 71% of affected sibs and 36% of clinically healthy sibs had decreased chemotaxis. For Aa seropositive probands, 83% of affected siblings and 65% of currently healthy sibs were also seropositive. The associations of disease with these risk factors were stronger in JP-only sibships. Some affected sibs had neither risk factor, while many currently healthy sibs had 1 or both. While these 2 factors demonstrate population association with disease, neither fits the pattern expected within families to clearly suggest a causal mechanism. The assessment of within and among family variability remains the best approach for recognition of possible causal mechanisms and sources of heterogeneity.

Re-interpretation of the evidence for X-linked dominant inheritance of juvenile periodontitis

Several studies have provided evidence supporting the inheritance of juvenile periodontitis (JP) in a Mendelian fashion, and both X-linked and autosomal modes of transmission have been proposed. Re-examination of the evidence for the X-linked dominant hypothesis reveals that two assumptions were crucial in favoring the X-linked rather than an autosomal hypothesis of JP transmission. The first assumption was that females are more likely than males to have JP by ratios of approximately 2.5:1. The second key observation was the reported lack of father to son transmission of the trait. However, the data that these assumptions were based on may be interpreted differently. Although the number of females reported to be affected by JP is greater than the number of affected males, this is probably a reflection of the greater number of females incorporated into these studies. When the proportions of affected males and females are examined, rather than total numbers of affected individuals, the proportion of affected males and females is similar. Additionally, the reported lack of father to son transmission for JP appears to be the result of incomplete family data. The female ascertainment bias inherent in many JP studies, compounded by the lack of male participation in such studies, appears to have resulted in the perception of a lack of male to male transmission of JP. This lack of observed father to son transmission of JP in incomplete data sets has been regarded as proof of no male to male transmission for the trait. Studies of more complete family data, however, do document father to son transmission of JP.(ABSTRACT TRUNCATED AT 250 WORDS)