Biomedical subjects

R J Genco

Publications and source records attributed to R J Genco.

At least 127 records · Page 7Linked to original sources

PubMed1991

The use of genomic DNA fingerprinting in studies of the epidemiology of bacteria in periodontitis.

Recent studies of microbial epidemiology emphasizing the genetic organization and distribution of organisms associated with orofacial infections have led to new insights into the possible origins of pathogenicity. Studies into genetic heterogeneity, acquisition and transmission of these organisms have been markedly advanced by the utilization of the powerful technique of genomic DNA fingerprinting. Characteristic fingerprints for each bacterial isolate can be produced by cleavage of high molecular weight genomic DNA by restriction endonucleases. It is assumed that each DNA fingerprint represents a clonal type. In this report, we review and analyze studies of the epidemiology of bacteria associated with orofacial infections with an emphasis on periodontal disease. Studies of nontypable (NT) Haemophilus influenzae associated with recurrent otitis media illustrate the utility of this technique. DNA fingerprinting clearly demonstrates genetic heterogeneity of NT H. influenzae isolates, and clonality of infection of any individual. Furthermore, DNA fingerprinting has shown that the same clonal type is seen in siblings concurrently suffering from otitis media, suggesting horizontal transmission within the family. Studies of mutans Streptococci also show extensive genetic heterogeneity and show vertical transmission of a predominant clonal type only from mother to infant, but not from father to infant. Studies of Actinobacillus actinomycetemcomitans show considerable genetic heterogeneity among monkey isolates. Thus far, three clonal types have been reported with DNA fingerprinting among isolates from periodontal patients, but additional genetic heterogeneity can be found using specific DNA fragments as probes in hybridization experiments. Intrafamilial transmission of A. actinomycetemcomitans has been demonstrated. Porphyromonas (Bacteroides) gingivalis shows extensive genetic heterogeneity and case reports suggest clonal infection of any one individual. In contrast, results with DNA fingerprinting of Eikenella corrodens, Fusobacterium nucleatum, and Bacteroides intermedius show that individuals may be infected with 2 or more clonal types. These studies point to the great potential of DNA fingerprinting for investigating the epidemiology of putative orofacial pathogens. Such studies with periodontal microorganisms will likely reveal steps in the acquisition, intraoral and person-to-person transmission, which then could possibly be inhibited or interfered with to prevent periodontal disease or its recurrence.

Bacteria↗

PubMed1991

Dental bacterial plaques. Nature and role in periodontal disease.

Antony van Leeuwenhoek first described oral bacteria. However, not until almost 200 years later was the famous Koch postulate introduced. Since then, research has extensively been performed regarding the development and microbiology of dental plaques. In spite of the complexity of the developing flora of supragingival plaque, culture studies have shown a remarkably orderly succession of organisms. Lately, the concept of microbial specificity in the etiology of periodontal diseases has been widely suggested, i.e., that different forms of periodontal disease are associated with qualitatively distinct dental plaques. Cross-sectional and longitudinal studies of the predominant cultivable microflora reveal that only a small number of the over 300 species found in human subgingival plaques are associated with periodontal disease. Among the commonly mentioned are: Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Bacteroides intermedius, Capnocytophaga sp., Eikenella corrodens, Fusobacterium nucleatum, and Wolinella recta, as well as certain gram-positive bacteria such as Eubacterium species. Anti-infective therapy for many systemic infections equals the use of antimicrobial drugs. However, for localized infections like periodontal diseases, treatment may consist of a combination of mechanical wound debridement and the application of an antimicrobial agent. The general effectiveness of mechanical anti-infective therapy and successful oral hygiene in the management of periodontal disease is well established in the literature and has met the test of success in clinical practice for most cases of periodontitis in adults. The definition of periodontal pathogens as either opportunistic pathogens, or as exogenous pathogens carries with it significant implications.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacterial Infections↗

PubMed1991

Porphyromonas (Bacteroides) gingivalis fimbrillin: size, amino-terminal sequence, and antigenic heterogeneity.

Bacterial fimbriae mediate cell adhesion and are important in colonization. Fimbrial proteins from strains of Porphyromonas (Bacteroides) gingivalis isolated from different individuals were compared for their size, amino-terminal sequence, and antigenic diversity. Two major protein components of the crude fimbrial preparations differed in apparent molecular mass, ranging from 41 to 49 kDa for the fimbrillin monomer and from 61 to 78 kDa for the other major protein. The amino-terminal sequence of the antigenically related group of proteins of the fimbrillin monomer in the 41- to 49-kDa range showed significant homology; however, minor sequence heterogeneity was observed, mainly in residues 4 to 6. One of the observed amino-terminal sequences, AFGVGDDESKVAKLTVMVYNG, resembled the deduced sequence of P. gingivalis 381 (D.P. Dickinson, M. K. Kubiniec, F. Yoshimura, and R.J. Genco, J. Bacteriol. 170:1658-1665, 1988). Fimbriae from all the strains of P. gingivalis showing this sequence contained a fimbrillin monomer of 43 kDa and showed a strong reaction with both polyclonal and monoclonal antibodies directed to the fimbriae from P. gingivalis 2561 (381). Fimbriae from strains showing amino-terminal sequence variations in residues 4 to 6 (i.e., substitution of VGD with either E or NAG) were more diverse in their molecular sizes. Most of these variant fimbriae showed weak reactions with the polyclonal antibodies and no reaction with the monoclonal antibodies induced to the fimbriae of strain 2561. No correlation could be established between the molecular size and immunological reactivity of the fimbrillin monomer of P. gingivalis strains. Strains 9-14K-1 and HG 564 not only showed markedly different sequences from the other three amino-terminal sequences but also did not react with either polyclonal or monoclonal antibodies to the fimbriae of strain 2561. Strains W50, W83, and AJW 5 failed to show any immunological reactivity with the antibodies to fimbrillin or fimbriae of strain 2561. Fimbriae from different strains revealed different immunologic reactions with rabbit antisera to each of the synthetic peptides of residues 59-78 (peptide I), 79-100 (peptide J), and 91-108 (peptide E) of strain 381. These results suggest that P. gingivalis fimbrillin subunits have size, sequence, and antigenic heterogeneity among the strains and that these differences may be important in the function and immune reactivities of the fimbriae.

Amino Acid Sequence↗

PubMed1991

Humoral immunity of older adults with periodontal disease to Porphyromonas gingivalis.

The effect of age on the humoral response to Porphyromonas gingivalis was assessed in groups of adults (25 to 54 years and 55 to 74 years) with periodontal disease and compared with that in age-matched healthy controls. To determine whether there was an antibody response against P. gingivalis, we measured serum antibodies against whole cells of P. gingivalis 381, A7A1-28, and W50. In addition, antibody levels against purified P. gingivalis outer membrane proteins (i.e., the 43-kDa fimbrial protein and a 75-kDa protein) were also evaluated. Elderly subjects showed the same response to P. gingivalis as younger subjects. Immunoglobulin G (IgG) antibodies to both purified proteins were also elevated in both diseased groups as compared with the normal groups. Total serum IgG, IgA, and IgM levels were also determined by an enzyme-linked immunosorbent assay for all four groups. Total serum IgG levels were elevated in older adults with periodontitis and total IgA levels were elevated in both groups of older adults compared with the younger groups of similar disease status. Total serum IgM levels were comparable for the four groups. Antinuclear antibody titers were assessed in the two groups of older adults and were also found to be higher for the group with periodontitis. These studies show that older adults as well as younger adults have markedly elevated specific antibodies of the IgG and IgA classes to antigens of P. gingivalis, a putative pathogen in both groups. Furthermore, older adults with periodontitis have significantly elevated levels of total serum IgG which may possibly be related to higher levels of autoantibodies.

Adult↗

PubMed1991

Human immunoglobulin G antibody response to iron-repressible and other membrane proteins of Porphyromonas (Bacteroides) gingivalis.

The human immunoglobulin G (IgG) immune response against Porphyromonas (Bacteroides) gingivalis A7A1-28 iron-repressible membrane proteins (IRMPs) and other membrane proteins was examined by immunoblot analysis. Thirty sera from patients with adult periodontitis and 30 sera from periodontally healthy subjects were included. Iron limitation of P. gingivalis was achieved by growing bacteria in brain heart infusion broth supplemented with protoporphyrin IX and 250 microM alpha, alpha'-dypyridyl, a ferrous iron chelator. Iron-sufficient growth was achieved by growing bacteria in the same medium without alpha, alpha'-dypyridyl. Human sera, in particular those from patients with periodontitis who exhibited high levels of IgG against whole cells of P. gingivalis A7A1-28 in serum in an enzyme-linked immunosorbent assay (ELISA), commonly reacted with five membrane proteins with apparent molecular masses of 80, 67.5, 51, 40.5, and 28 kDa and four IRMPs of 46, 43, 37.5, and 22 kDa. More than 80% of the sera from patients with periodontitis and high levels of IgG against strain A7A1-28 in serum by ELISA reacted with the 46-, 43-, and 37.5-kDa IRMPs, and 40% of these subjects expressed immunoreactivity against the 22-kDa IRMP. Sera from patients with periodontitis and low levels of IgG against strain A7A1-28 in serum by ELISA and sera from periodontally healthy subjects exhibited less immunoreactivity against IRMPs and the five membrane proteins of P. gingivalis. The present study indicates that P. gingivalis IRMPs are immunogenic and that these proteins are expressed in vivo.

Antibodies, Bacterial↗

PubMed1991

Using antimicrobial agents to manage periodontal diseases.

Periodontal diseases are bacterial infections and anti-microbials have been shown to be useful in their treatment and prevention. State-of-the-art treatment of refractory forms of destructive periodontal disease presently includes adjunctive use of systemic antibiotics directed to eliminating or suppressing pathogenic subgingival bacteria. Also, local application of antimicrobials by subgingival deposition or their use as irrigants during periodontal therapy are soon likely to be major components of anti-infective management of periodontal diseases. A new approach to anti-infective periodontal therapy combines ultrasonic surgical debridement with antimicrobial irrigation.

Anti-Bacterial Agents↗

PubMed1991

Periodontal disease in non-insulin-dependent diabetes mellitus.

The relationship between diabetes mellitus and oral health status was determined in Pima Indians from the Gila River Indian Community in Arizona. This tribe of native Americans has the world's highest reported incidence and prevalence of non-insulin-dependent (type 2) diabetes mellitus. The probing attachment level, alveolar bone loss, age, sex, Calculus Index, Plaque Index, Gingival Index, fluorosis, and DMFT as well as the diabetic status was assessed in 1,342 Pima Indians who were at least partially dentate. The prevalence and severity of destructive periodontal disease was determined by measuring probing attachment loss and radiographically apparent interproximal crestal alveolar bone loss, two independent but correlated indicators of periodontal destruction. Only diabetic status, age, and the presence of subgingival calculus were significantly associated with both increased prevalence and greater severity of destructive periodontal disease in this population. Diabetic status was significantly and strongly related to both the prevalence and severity of disease after adjusting for the effects of demographic variables and several indices of oral health including the Plaque Index. Subjects with type 2 diabetes have an increased risk of destructive periodontitis with an odds ratio of 2.81 (95% confidence interval 1.91 to 4.13) when attachment loss is used to measure the disease. The odds ratio for diabetic subjects was 3.43 (95% confidence interval 2.28 to 5.16) where bone loss was used to measure periodontal destruction. These findings demonstrate tht diabetes increases the risk of developing destructive periodontal disease about threefold. Furthermore, diabetes increases the risk of developing periodontal disease in a manner which cannot be explained on the basis of age, sex, and hygiene or other dental measures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1991

Purification, characterization, and localization of a major membrane protein antigen from Porphyromonas (bacteroides) gingivalis.

Humans and rats infected with P. gingivalis develop a strong immune response to a 75 kDa major membrane component of P. gingivalis and hence knowledge of the nature of this molecule may aid in understanding the host response to P. gingivalis during infection. Purification of the 75 kDa protein was achieved by repeated precipitation from a crude sonicate of P. gingivalis 2561 at pH 5.0. Homogeneity of the purified 75 kDa protein was confirmed by SDS-PAGE and Western immunoblot analysis using monoclonal and polyclonal antibodies. The purified protein revealed an apparent molecular mass of 300 kDa in native form. Although most of the strains of P. gingivalis tested showed a major membrane protein band in the range of 61 to 78 kDa, on Western immunoblot analysis only the strains which have proteins in the range of 75 to 78 kDa were reactive with anti-75 kDa protein polyclonal antibodies. Affinity purified polyclonal antibodies were used to localized 75 kDa protein on the cell surface of P. gingivalis 2561 by immunogold electron microscopy. Immunolabeling of the 75 kDa protein demonstrated specific localization of the protein along the outer cell membrane, but not on the fimbriae. Furthermore, immunogold labeling of the 75 kDa protein on the thin sections showed that the 75 kDa component was present on not only the outer membrane, but also on the cell membrane, and on membrane bound organelles. Localization of this protein suggests that the 75 kDa component is a membrane-associated protein.

Amino Acids↗

PubMed1991

Localization of ligand binding regions of the human formyl peptide receptor.

The formyl peptide receptor is involved in the activation of human neutrophils (PMN) and their subsequent response to chemotactic peptides such as FMLP. The normal FMLP receptor has been reported to contain both high and low affinity states and to consist of several glycoprotein components, ranging in size from 40-94 kDa. However, little is known about the functional domains of the receptor. In this study we have constructed synthetic peptides corresponding to different portions of the reported receptor structure, and have tested their involvement in ligand binding. One of these peptides, corresponding to the first extracellular loop of the N-terminus end of the molecule, has been shown to specifically inhibit FMLP binding to PMN membranes. Concomitantly, this peptide exhibited the strongest direct binding to the ligand. We propose that this portion of the FMLP receptor molecule is important in receptor-ligand interactions.

Amino Acid Sequence↗

PubMed1990

Molecular cloning and expression of antigens from Actinobacillus actinomycetemcomitans in Escherichia coli.

In order to study the role of membrane proteins in mucosal colonization by Actinobacillus actinomycetemcomitans, a plasmid library was constructed by ligating EcoRI-digested genomic DNA from A. actinomycetemcomitans strain Y4 into EcoRI-digested and dephosphorylated pUC13 DNA. A second library was constructed by ligating Sau3A-digested and size-fractionated A. actinomycetemcomitans strain Y4 DNA into BamHI-cleaved and dephosphorylated pUC13 DNA. The DNA was transformed into Escherichia coli strain MC1022 and plated onto Luria-Bertani agar containing 100 micrograms/ml ampicillin and X-gal. Recombinant colonies were examined for the expression of A. actinomycetemcomitans antigens by colony immunoscreening using rabbit antiserum to strain Y4. Nine positive clones were isolated. Three of these clones produced proteins that reacted with rabbit antiserum to strain Y4 on a Western transfer, and seven of these clones reacted with rabbit antiserum to strain Y4 as measured by indirect immunofluorescence. One reactive clone contained an 8.4 kb plasmid, which directed the synthesis of a peptide with an Mr of 20,000 as measured by SDS-PAGE. Partial DNA sequence analysis revealed the presence of a signal-peptide leader sequence at the amino terminus suggesting that the native protein is a membrane component of A. actinomycetemcomitans. Thus A. actinomycetemcomitans antigens can be expressed in E. coli, and some of these proteins may be expressed on the E. coli cell surface.

Actinobacillus↗

PubMed1990

Genetic heterogeneity of Porphyromonas (Bacteroides) gingivalis by genomic DNA fingerprinting.

This study describes the use of total genomic DNA fingerprinting with the use of restriction endonucleases to characterize clinical isolates of Porphyromonas gingivalis (Bacteroides gingivalis) obtained from patients with periodontitis or with root-canal infections. The majority of independent isolates had a unique DNA fingerprint, indicating extensive genetic heterogeneity within this species. Twenty-nine distinct DNA fingerprints were found among the 33 isolates investigated. This is in contrast to biotyping and serotyping, where only one type and three types, respectively, have been reported. The observed heterogeneity indicates that DNA fingerprinting is a sensitive measure of genetic dissimilarity between P. gingivalis isolates and is able to characterize individual isolates. These results have ecological implications, indicating that there is considerable natural diversity in the global population of P. gingivalis, and that there are likely to be relatively large numbers of genetically distinct clonal lines. Furthermore, DNA fingerprinting is a sensitive and powerful tool for longitudinal and cross-sectional epidemiological studies. This technique provides far greater discrimination between isolates than either biotyping or serotyping, and will be most helpful in, for example, the analysis of distribution of clonal lines within one periodontal patient, or the analysis of the transmission to and turnover of strain populations within a patient population, since the probability of two strains with the same DNA fingerprint being found by chance is small.

Bacteroides↗

PubMed1990

Type 2 diabetes mellitus and periodontal disease.

The relationship between type 2 diabetes mellitus and periodontal disease was evaluated in 2,878 Pima Indians of the southwestern United States. Two independent measures of periodontal disease, probing attachment loss and radiographic bone loss, were used to compare prevalence and severity of periodontal disease in diabetic and nondiabetic subjects. In all age groups studied, subjects with diabetes had a higher prevalence of periodontal disease, indicating that diabetes may be a risk factor for periodontal disease.

Adolescent↗

PubMed1990

Antibodies directed to the chemotactic factor receptor detect differences between chemotactically normal and defective neutrophils from LJP patients.

Localized juvenile periodontitis (LJP) is a progressively destructive infection of the supporting tissues of the teeth, primarily affecting adolescents. In this disease, patients' polymorphonuclear leukocytes (PMN) exhibit decreased chemotaxis (CTX) and decreased binding of the chemotactic peptide N-formyl-l-methionyl-l-leucyl-l-phenyl-alanine (FMLP) to specific receptors on the PMN surface. Since the FMLP receptor is involved in the activation of the PMN, and its subsequent response to chemotactic stimuli, a decrease in the chemotactic peptide receptor, as seen in LJP patients, is suspected to be a predisposing factor for this disease. To define differences in the FMLP receptor between CTX defective LJP patients and CTX normal donors, a battery of monoclonal antibodies reactive against the FMLP receptor was prepared. The FMLP receptor was affinity-purified, and was found to be comprised of two components, one of 68 kDa, and the other of 94 kDa. Only the 68 kDa component specifically bound a radioiodinated FMLP analogue in a photoaffinity experiment. Seven monoclonal antibodies were selected on the basis of their reactivity with the 68 kDa receptor component, and of these, 5 showed reduced binding against PMN from CTX defective LJP donors when compared to their reactivity against PMN from CTX normal subjects. Two of the 7 anti-68 kDa antibodies reacted with PMN from both sets of subjects at a comparable extent. Furthermore, the presence of 20 nmol of FMLP inhibited the binding of 5 of the anti-receptor antibodies to whole PMN, including one that showed no difference in binding between CTX normal and defective PMN, and 4 of the 5 that did show such difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1990

Studies of the subgingival microflora in patients with acquired immunodeficiency syndrome.

Two unique forms of periodontal disease, HIV-gingivitis and HIV-periodontitis, have been described in patients with Acquired Immunodeficiency Syndrome (AIDS). In order to determine the bacterial species associated with periodontitis in AIDS patients, the predominant cultivable microflora was examined in 21 subgingival plaque samples from 11 AIDS patients with periodontitis. The presence of putative periodontal pathogens including Actinobacillus actinomycetemcomitans, Bacteroides intermedius, Porphyromonas gingivalis (formerly B. gingivalis), and Wolinella recta was examined by immunofluorescence in 128 subgingival dental plaque samples from 50 AIDS patients including 32 patients with periodontitis. Of 666 bacterial strains isolated from the 21 subgingival plaque samples, Streptococcus sanguis II was the most frequently recovered species comprising 18.5% of the total number of isolates followed by Lactobacillus acidophilus (12.2%), Porphyromonas gingivalis (12%), Fusobacterium nucleatum (11.4%), Staphylococcus epidermidis (8.7%), Actinomyces naeslundii (7.5%), and Actinomyces viscosus (4.7%). Fusobacterium nucleatum was the most prevalent species and was found in 76% of the sites and 91% of the patients. Enteric species including Enterococcus avium and Enterococcus faecalis, Clostridium clostridiiforme and Clostridium difficle as well as Klebsiella pneumoniae also were recovered. Immunofluorescence assays detected similar carriage rates of A. actinomycetemcomitans, B. intermedius, and P. gingivalis in both gingivitis patients and periodontitis patients, while four times more periodontitis patients demonstrated W. recta. Subgingival yeast was a frequent finding in these AIDS patients, present in 62% of the subjects and 55% of the sites. This study indicates that subgingival plaque in AIDS patients with periodontitis can harbor high proportions of the same periodontal pathogens as are associated with periodontitis in non-HIV infected subjects as well as high proportions of opportunistic pathogens.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Periodontal disease and NIDDM in Pima Indians.

The goal of this study was to determine the prevalence and incidence of periodontal disease and its relationship with non-insulin-dependent diabetes mellitus (NIDDM). Two thousand two hundred seventy-three Pima Indians (949 men, 1324 women) aged greater than or equal to 15 yr from the Gila River Indian Community in Arizona were examined between 1983 and 1989. Periodontal disease was diagnosed by tooth loss and by percentage of interproximal crestal alveolar bone loss ascertained from panoramic radiography. Subjects with little or no evidence of periodontal disease were classified as nondiseased. Thus, the incidence of advanced periodontal disease was determined. The age- and sex-adjusted prevalence of periodontal disease at first dental examination was 60% in subjects with NIDDM and 36% in those without. Twenty-two new cases developed in a subset of 701 subjects (272 men, 429 women) aged 15-54 yr who initially had little or no evidence of periodontal disease and had at least one additional dental examination. The incidence of periodontal disease in this group was similar in men and women (incidence-rate ratio 1.0, 95% confidence interval [Cl] 0.5-1.9, controlled for age and diabetes). Higher age predicted a greater incidence of periodontal disease (chi 2 = 30.6, df = 3, P less than 0.001, controlled for sex and diabetes). The rate of periodontal disease in subjects with diabetes was 2.6 times (95% Cl 1.0-6.6, controlled for age and sex) that observed in those without. Although periodontal disease was common in nondiabetic Pima Indians, in whom most of the incident cases occurred, diabetes clearly conferred a substantially increased risk. Thus, periodontal disease should be considered a nonspecific complication of NIDDM.

Adolescent↗

PubMed1989

Characterization of a polysaccharide antigen from Bacteroides gingivalis.

A polysaccharide Ag (PS) was isolated from the phenol-water extract of Bacteroides gingivalis strain A7A1-28 and separated from LPS by Sephacryl S-400 HR chromatography. The PS was composed of glucose, glucosamine, galactosamine, and galactosaminuronic acid, while the LPS contained rhamnose, mannose, galactose, glucose, glucosamine, galactosamine, phosphate, and lipid, but not galactosaminuronic acid. The PS and LPS were immunochemically distinct by immunoelectrophoresis in agarose with homologous rabbit antiserum. The phenol-water extract from strain A7A1-28 was immunoreactive by immunoelectrophoresis against antisera to three additional strains of B. gingivalis, however, the PS was only reactive with homologous serum. Immunochemical characterization of decarboxylated and deacetylated PS derivatives suggest that the acetylation of the amino sugars, but not the presence of the carboxylate residue on galactosaminuronic acid contributes to major immunodeterminant expression.

Antigens, Bacterial↗

PubMed1989

Effects of subgingival irrigation on A. actinomycetemcomitans.

The effects of repeated subgingival irrigation on Actinobacillus actinomycetemcomitans was examined. 24 periodontal pockets harboring A. actinomycetemcomitans in 3 juvenile and 4 adult periodontitis patients were studied. The protocol included bi-weekly subgingival irrigation with hydrogen peroxide of the periodontal sites until the micro-organism was no longer detected by selective culture, or for 6 months. A. actinomycetemcomitans was gradually suppressed to below detection following the irrigation regime and could no longer be detected in 46% of the sites at completion of the irrigation protocol. The sites were microbiologically re-examined 5 months after cessation of the irrigation regime. A. actinomycetemcomitans re-occurred in only 2 of the sites from which it had originally been suppressed below detection. The results indicate: (1) that the irrigation regime tested has some potential to suppress A. actinomycetemcomitans in periodontal pockets; (2) that the effect of the irrigation protocol generally lasted for 5 months; (3) that the reduction rate of A. actinomycetemcomitans to below detectable levels seems related to the initial number of cultivable bacteria from the periodontal pocket.

Actinobacillus↗

PubMed1989

Effect of x-ray beam vertical angulation on radiographic alveolar crest level measurement.

Utilizing intraoral radiographs of human skulls taken at known vertical angulation, we have demonstrated that expression of the crest level as a distance between cej and the crest is as accurate as a ratio of bone height to root length. The degree of inaccuracy of either of these measures is related to the magnitude of the angular deviation of the x-ray beam from 90 degrees. Angular deviation can be estimated from calculation of a cusp height score (ratio of lingual cusp height to buccal cusp height x 100). Based on the analysis of cusp height scores it was determined that the x-ray beam angulation for posterior bitewings ranged between 90 degrees and 80 degrees whereas for posterior periapicals the angulation range was between 90 degrees and 70 degrees. Therefore, it is recommended that, for longitudinal studies of bone height, measurements of the crest to cej distance, particularly in the region of the molars, be made utilizing bitewing radiographs. For the premolar and incisor regions, deviation of the vertical angulation of an x-ray of up to 20 degrees from a 90 degrees baseline resulted in little, if any, change in crest level by either one of the two measures used. An appendix is provided for the theoretical modeling of the types and magnitude of change in crest level observed for projection images of different anatomical configurations.

Alveolar Process↗