Robert G. Dunford

Cigarette Smoking Increases the Risk for Subgingival Infection With Periodontal Pathogens

Cigarette smoking has been found to increase the risk for periodontitis. The present study examined the association between cigarette smoking and subgingival infection with periodontal pathogens to determine if smokers are more likely to be infected with certain periodontal pathogens than non-smokers. Self-reported data on 1,426 subjects, aged 25 to 74, from the Erie County Study were obtained including data on 798 subjects who were current or former smokers. Mean clinical attachment loss was used to estimate the severity of periodontal destruction. Subgingival infection with target periodontal pathogens was determined by indirect immunofluorescence microscopy. Smokers harbored significantly higher levels and were at significantly greater risk of infection with Bacteroides forsythus than non-smokers. Adjusting for disease severity, the risk of subgingival infection with B. forsythus in current smokers was 2.3 times that of former smokers or non-smokers. The relative risk of B. forsythus infection also increased 1.18 times for every category of smoking as the amount of smoking measured in packyears increased from very light to heavy. Adjusting for disease severity, Porphyromonas gingivalis was also more likely to subgingivally infect smokers than non-smokers; however, there was not a significantly higher relative risk for infection with this bacterium. The data from this study indicate that cigarette smoking increases the likelihood of subgingival infection with certain periodontal pathogens. This may partly explain the increased risk for periodontitis seen in smokers. J Periodontol 1996;67:1050-1054.

Usefulness of Subtraction Radiography in the Evaluation of Periodontal Therapy

Subtraction radiography, a sensitive and accurate technique for identifying alveolar crestal change from standardized pairs of radiographs, is useful in monitoring periodontal therapy. One half of the radiographs were found to be appropriate for subtraction analysis using present technology for taking standardized radiographs. The criterion for usability was identical interpretation of subtraction images made in duplicate from a pair of radiographs. A set of radiographs was analyzed by subtraction radiography as well as by measurement of alveolar bone-crest height. Subtraction radiography was found to be more sensitive in detecting change. Whereas 53% pairs of radiographs showed a change on subtraction radiography, only 14% showed a change in crest height. Comparison of change by subtraction radiography and probing attachment level showed an overall correlation. Since these two measures assess different aspects of the periodontium, perfect correlation was not expected.

A Statistical Approach to the Ecology of Porphyromonas gingivalis

Previous studies have suggested that infections with Porphyromonas gingivalis, associated with periodontal disease, may consist of one clonal type. It has also been shown that each individual patient carries a unique clonal type of P. gingivalis, as assessed by DNA fingerprinting. This issue was further examined by random collection of multiple isolates ofP. gingivalis from multiple sites in several patients, and characterization of these isolates by DNA fingerprinting. Although most patients appeared to be infected exclusively by one clonal type of P. gingivalis, at least one patient was found to harbor two distinct clonal types. This indicates that the simultaneous presence of different clonal types of P. gingivalis can occur. A statistical method was developed for retrospective analysis of these data for estimation of whether the remainder of these patients were actually infected with single or multiple clonal types ofP. gingivalis. With this statistical method, a confidence interval was calculated for estimation of the true proportion of a single observed clonal type in the potential population of P. gingivalis that might be recovered from an infected patient. Statistically, the sampling of small numbers of sites per patient or isolates per site leads to a wide confidence interval for the estimated true proportion of the observed clonal type in the infecting P. gingivalis population. For example, when five sites in an oral cavity yield indistinguishable P. gingivalis isolates, then the true proportion of this clonal type in the total P. gingivalis population in the infected oral cavity is estimated to be in the interval between 55% and 100% (at a 95% confidence level). If the isolates from all sampled sites from a periodontal patient appear to be of the same clonal type, it can be calculated that at least 29 different sites must be sampled for this observed clonal type to represent at least 90% of the P. gingivalis population in this patient (95% confidence level); this was termed the LTP, or lowest true proportion. Such calculations can also be used for estimation of the LTP of a clonal type infecting a single oral site in a periodontal patient. These results confirm the commonly held opinion that studies investigating the ecology of P. gingivalis and other suspected pathogens must be designed on a large scale in order for statistically meaningful results to be obtained.

Skeletal osteopenia and residual ridge resorption

Increased residual ridge resorption resulting from postmenopausal skeletal osteopenia has been a long-standing clinical assumption. This study was conducted to determine the relationship between the degree of residual ridge resorption, sex, and the age of the patient. The technique of measuring mandibular resorption uses panoramic radiographs as described by Wical and Swoope. Six readers received technique instructions and were then tested for uniformity. An analysis of variance demonstrated no significant difference between readers (p greater than 0.10). A random selection of 459 radiographs of edentulous patients were then measured by using a blind technique to determine the amount of residual ridge resorption. Analysis of this data demonstrated a significantly larger percentage of women with class 3 (severe) residual ridge resorption (p less than 0.01) but this difference could not be related to the occurrence of menopause.

Monitoring of Subgingival Bacteroides Gingivalis and Actinobacillus Actinomycetemcomitans in the Management of Advanced Periodontitis

In a series of clinical trials involving 79 adult periodontitis patients, we evaluated the clinical and microbiological effects of H2O2, NaHCO3, and a commercially available povidine solution, as adjuncts to mechanical periodontal debridement. Each trial included a placebo as a control. The healing response was monitored clinically by measurement of changes in probing attachment levels after treatment. The current report includes data from single-rooted teeth only. In general, healing in severely advanced periodontal lesions (initial pocket depth ≥ 7 mm) was enhanced by the use of the listed topical antimicrobial agents administered subgingivally during mechanical debridement. Correlations were sought between changes in probing attachment levels 12 months after treatment, and the presence of subgingival B. gingivalis and A. actinomycetemcomitans in the periodontal lesions. For a total of 428 lesions included in this report, B. gingivalis was detected in 53.1% of lesions showing probing attachment loss (≥1.5 mm), but in only 4.7% of lesions showing gain (≥ 1.5 mm). Either B. gingivalis or A. actinomycetemcomitans was detected in 70.1% of the lesions showing loss and in only 4.8% of those showing gain. These studies indicate the benefits of the adjunctive antimicrobial therapy described, and the usefulness of specific microbiological monitoring as an aid to clinical measurements in the evaluation of success or failure of treatment of chronic adult periodontitis.

Correlations between Gingival Crevicular Fluid Enzymes and the Subgingival Microflora

Bacteroides gingivalis is a Gram-negative micro-organism implicated in the pathogenesis of adult periodontitis and producing relatively large amounts of specific enzymes. In the present study, subgingival samples taken from adults with moderate periodontitis were examined for the presence and relative amounts of enzymatic activity toward certain substrates. Enzyme levels were then correlated with clinical periodontal indices and microbiological analysis of subgingival plaque, including darkfield microscopy for bacterial morphotypes and immunofluorescence microscopy for B. gingivalis and Bacteroides intermedius. The results of this study indicate a significant positive correlation between levels of enzyme capable of degrading N-benzoyl-D,L-arginine-β-naphthylamide hydrochloride, and subgingival B. gingivalis (r = 0.55). There was a much lower correlation coefficient between this enzyme activity and subgingival B. intermedius (r = 0.26). Statistically significant (p < 0.01) positive correlations were also demonstrated between total bacterial cell counts and levels of enzymatic activity against N-benzoyl-D,L-arginine-B-naphthylamide hydrochloride (r = 0.76), N-carbobenzoxy-glycyl-glycyl-L-arginine-β-naphthylamide hydrochloride (r = 0. 72), and glycyl-L-proline-4-methoxy- β-naphthylamide hydrochloride (r = 0.69). There were significant differences in the levels of these three enzymatic activities between sites exhibiting various degrees of clinical severity of gingival inflammation and harboring various proportions of B. gingivalis. The data from this study indicate that measurement of specific enzymatic activities in subgingival samples can be useful in the diagnosis of B. gingivalis-associated periodontitis.

In vitro model to evaluate reliability and accuracy of a dental shade-matching instrument

STATEMENT OF PROBLEM There are several electronic shade-matching instruments available for clinical use; unfortunately, there are limited acceptable in vitro models to evaluate their reliability and accuracy. PURPOSE The purpose of this in vitro study was to evaluate the reliability and accuracy of a dental clinical shade-matching instrument. MATERIAL AND METHODS Using the shade-matching instrument (ShadeScan), color measurements were made of 3 commercial shade guides (VITA Classical, VITA 3D-Master, and Chromascop). Shade tabs were selected and placed in the middle of a gingival matrix (Shofu Gummy), with tabs of the same nominal shade from additional shade guides placed on both sides. Measurements were made of the central region of the shade tab inside a black box. For the reliability assessment, each shade tab from each of the 3 shade guide types was measured 10 times. For the accuracy assessment, each shade tab from 10 guides of each of the 3 types evaluated was measured once. Reliability, accuracy, and 95% confidence intervals were calculated for each shade tab. Differences were determined by 1-way ANOVA followed by the Bonferroni multiple comparison procedure. RESULTS Reliability of ShadeScan was as follows: VITA Classical = 95.0%, VITA 3D-Master = 91.2%, and Chromascop = 76.5%. Accuracy of ShadeScan was as follows: VITA Classical = 65.0%, VITA 3D-Master = 54.2%, Chromascop = 84.5%. CONCLUSIONS This in vitro study showed a varying degree of reliability and accuracy for ShadeScan, depending on the type of shade guide system used.

Salivary film formation on defined solid surfaces in the absence and presence of microorganisms

A salivary derived proteinaceous film will condition any surface exposed in the oral cavity prior to cell attachment. Studies have shown a strong correlation between the initial surface properties of a material and its cell retaining capacity, indicating that a mechanism may exist by which surface characteristics of a solid are transmitted through the adsorbed film. The aim of this study was to monitor the film organization of salivary secretions at defined liquid‐solid interfaces, and to evaluate the effect of the critical surface tension and the presence of microorganisms on the packing of the films. Fresh secretions from human parotid (HPS) and submandibular‐sublingual glands (HSMSL) were allowed to form thin films on surfaces of low and medium critical surface tensions under controlled flow conditions, in the presence and absence of microorganisms. Two strains of Streptococcus salivarius and Streptococcus sanguis were used as test microorganisms. The resulting films were monitored in situ by nondestru...

Crestal Alveolar Bone Change in Patients with Periodontitis as Observed by Subtraction Radiography: An Overview

Subtraction radiography is a highly sensitive and useful technique for detecting crestal alveolar bone changes in patients. Utilizing this technique, researchers have demonstrated that 9% of crestal sites lose bone over a six-month period in untreated subjects with periodontitis. On the order of 10-13% of crestal sites were found to lose bone three months post-periodontal therapy which included surgery. Non-surgical therapy resulted in 0.5-2% of crestal sites with bone loss. Subtraction requires radiographs which have closely approximating projection geometry. Presently available technology for taking standardized radiographs based on an occlusal stent system is adequate for obtaining interpretable subtraction images.

Infield masticatory muscle activity in subjects with pain‐related temporomandibular disorders diagnoses

OBJECTIVES Pain-related temporomandibular disorders (TMDs) are the most prevalent conditions among TMDs. There is contrasting evidence available for association of pain-related TMD and masticatory muscle activity (MMA). The present investigation assesses the associations between MMA levels of masseter and temporalis muscles during awake and sleep among pain-related TMD diagnostic groups. SETTING AND SAMPLE POPULATION The department of Oral Diagnostic Sciences, University at Buffalo. Twenty females and six males participated in this study. MATERIAL AND METHODS Using the diagnostic criteria for temporomandibular disorders (DC-TMDs), participants were diagnostically categorized. Subjects used a custom monitoring system, which recorded infield muscle activities. A factorial model tested for association between independent variable (muscle, time period, MMA level, and diagnostic group) effects and the logarithm of MMA. Greenhouse-Geisser test was used to determine any statistically significant associations (p≤0.003). RESULTS No statistically significant association was found between four-way, three-way, and two-way analyses. However, among the main effects, range of magnitudes was the only variable to be statistically significant. Although the data suggest a trend of increased masseter MMA in the pain-related TMD diagnoses group both during awake and sleep time periods, such observation is not maintained for the temporalis muscle. In addition, temporalis MMA was found to be higher in the pain-related TMD diagnoses group only at extreme activity levels (<25 and ≥80% ranges). CONCLUSION This data support the association between masticatory muscle hyperactivity and painful TMD conditions.