Clinical evaluation of periodontal diseases

Ultrasound detection of submerged dental implants through soft tissue in a porcine model

STATEMENT OF PROBLEM

Current methods of measuring soft tissue thickness over potential dental implant sites and locating submerged implants may be imprecise or invasive.

PURPOSE

The purpose of this study was to develop and demonstrate proof of the concept of a customized ultrasound imaging system in locating and measuring the depth of implants submerged beneath soft tissue.

MATERIAL AND METHODS

A complete ultrasound system, including a customized soft tissue-matched transducer, transceiver, and digital signal processing algorithms, was created for the specific application of detecting dental implants anchored in bone beneath soft tissue. The system was used to locate implants placed in cancellous bone and measure overlying soft tissue depth in a porcine model. Ten measurements were made on each porcine model by manually moving the transducer laterally over the soft tissue surface. Data were analyzed with descriptive statistics.

RESULTS

The mean signal-to-noise ratio, SNR (standard deviation), from the bone surfaces, was 19.1 (4.6) dB, and the mean SNR from the implant surfaces was 36.6 (2.2) dB, resulting in a mean difference of 17.5 dB, or x56.2, in average signal power between the bone and implant surfaces. Consequently, implants were easily and accurately (+/-0.2 mm) located beneath at least 5 mm of soft tissue. Likewise, soft tissue depths over bone and implants were accurately measured and were within the corresponding caliper tissue measurement error (+/-0.5 mm).

CONCLUSIONS

The specialized ultrasound imaging system located and measured the depth of implants placed in bone submerged beneath soft tissue in a porcine model.

GMP-grade preparation of biomimetic scaffolds with osteo-differentiated autologous mesenchymal stromal cells for the treatment of alveolar bone resorption in periodontal disease

BACKGROUND

Periodontal disease is a degenerative illness that leads to resorption of the alveolar bone. Mesenchymal stromal cells (MSC) represent a novel tool for the production of biologic constructs for the treatment of degenerative bone diseases. The preparation of MSC differentiated into osteogenic lineage for clinical use requires the fulfillment of strict good manufacturing practice (GMP) procedures.

METHODS

MSC were isolated from BM samples and then cultured under GMP conditions. MSC were characterized phenotypically and for their differentiative potential. Cells were seeded onto collagen scaffolds (Gingistat) and induced to differentiate into osteogenic lineages using clinical grade drugs compared with standard osteogenic supplements. Alizarin Red S stain was used to test the deposition of the mineral matrix. Standard microbiologic analysis was performed to verify the product sterility.

RESULTS

The resulting MSC were negative for CD33, CD34 and HLA-DR but showed high expression of CD90, CD105 and HLA-ABC (average expressions of 94.3%, 75.8% and 94.2%, respectively). Chondrogenic, osteogenic and adipogenic differentiation potential was demonstrated. The MSC retained their ability to differentiate into osteogenic lineage when seeded onto collagen scaffolds after exposure to a clinical grade medium. Cell numbers and cell viability were adequate for clinical use, and microbiologic assays demonstrated the absence of any contamination.

DISCUSSION

In the specific context of a degenerative bone disease with limited involvement of skeletal tissue, the combined use of MSC, exposed to an osteogenic clinical grade medium, and biomimetic biodegradable scaffolds offers the possibility of producing adequate numbers of biologic tissue-engineered cell-based constructs for use in clinical trials.

Characterization of Serratia marcescens isolates from subgingival biofilm, extraoral infections and environment by prodigiosin production, serotyping, and genotyping

INTRODUCTION

Serratia marcescens is widely distributed in nature, and has emerged in the last years as an important nosocomial pathogen. The organism may also be found in subgingival biofilm in periodontitis patients. This study aimed to verify the subgingival prevalence of S. marcescens in different periodontal conditions and to evaluate whether the oral cavity would harbor strains similar to those causing infectious diseases.

METHODS

The subgingival occurrence of S. marcescens was determined in 334 subjects. The phenotypic and genotypic diversity of 23 isolates from subgingival biofilm, 22 from extra-oral infections and 10 environmental strains, was compared by prodigiosin production, O and H serotyping and genotyping using polymorphic GC-rich repetitive sequences-polymerase chain reaction.

RESULTS

S. marcescens was found more frequently in severe periodontitis patients (4.1%) than in gingivitis (3.2%) and healthy subjects (2.5%), but these differences were not statistically significant. Analysis of serotype distribution, prodigiosin production, and genotyping revealed that environmental strains were markedly different from most human isolates, either oral or extraoral.

CONCLUSION

These data suggest that S. marcescens isolates from subgingival biofilm are not just contaminants from the environment, but that the oral cavity may act as a reservoir of strains able to promote human infections. However, further studies are needed to elucidate the role of this bacterium in the pathogenesis of periodontal diseases.

Improving patients' compliance with the treatment of periodontitis: a controlled study of behavioural intervention

OBJECTIVES

This clinical trial study investigates whether a behavioural educational intervention based on the autoregulation theory can improve periodontitis patients' compliance with proper dental care at a 1-month follow-up.

MATERIAL AND METHODS

Thirty patients matched for gender (20 men), age (mean age=39 years) and education were randomly assigned to a control or an experimental treatment condition. In the control condition, patients received the regular treatment based on instruction of the proper prophylactic dental care. In the experimental treatment condition, patients received information about the symptoms of periodontitis, the causes, consequences and temporal course, and the types of effective strategy and they were requested to keep daily records of the effects of applying prophylactic dental care on their periodontitis symptoms. In both groups, plaque indices (PIs) (Silness & Löe 1964) were measured prior to treatment and at a 1-month follow-up. A self-report questionnaire also assessed the representation of periodontitis in all patients.

RESULTS

A 2 (time of measurement: baseline versus follow-up) x 3 (PI localization) x 2 (experimental group) mixed-design anova computed on the PI reports a large effect of time, F(1, 28)=267.10, p<0.000, indicating that both groups improved from baseline (mean=1.73, SD=0.08) to the 1-month follow-up (mean=0.56, SD=0.06). It is important to point out that this analysis also revealed the expected Group x Time interaction, F(1, 28)=7.09, p<0.02, partial eta(2)=0.19, indicating that smaller PI were observed in the experimental group (mean=0.24, SD=0.14) than in the control group (mean=0.88, SD=0.38) at follow-up. Post hoc analyses showed that this pattern applies to the proximal and lingual PI but not to the vestibular PI.

CONCLUSIONS

The present data show that the behavioural education intervention is (a) more effective than a classical intervention based on information and training about prophylactic techniques and (b) that it is effective in bringing most patients to normal levels of PI. For clinical practice, it suggests that better results can be obtained if (a) patients are taught a correct representation about periodontitis and (b) patients' sense of self-efficacy is developed through their own direct experience, by observing the effects of their behaviour on periodontitis symptoms.

Periodontal disease and diabetes mellitus

Infections of the tissue surrounding the teeth (periodontitis) are usually caused by anaerobic gram-negative microorganisms. This infection causes destruction of the supporting alveolar bone and can lead to tooth loss. Removal of these microorganisms can slow or arrest the progression of periodontitis. Diabetes patients are at greater risk of developing periodontitis, may not respond as well to periodontal therapy as nondiabetic patients, and may require more aggressive treatment to manage periodontitis. Microorganisms that cause periodontitis and the host response to these may increase insulin resistance in diabetic patients. Treatment of periodontitis could improve glycemic control. A model is presented in which periodontal pathogens may cause increases in proinflammatory cytokines that mediate increases in insulin resistance, resulting in an increase in blood glucose. Following periodontal therapy, this process may be reversed.

Periodontal ultrasonography

OBJECTIVES

The aim of this study was to investigate high-frequency ultrasound imaging for periodontal assessment.

MATERIAL AND METHODS

A newly developed ultrasonic scanner with a frequency of 20 MHz was used. Pig jaws were selected as the experimental model. Three teeth per jaw were imaged with the scanner and duplicate measurements were made of the distance from a fixed landmark on the teeth to the alveolar bone crest. These measurements were compared to transgingival and direct measurements of the same teeth following reflection of the soft tissues. One further jaw was used for histological comparison with the ultrasound image.

RESULTS

Using ultrasonography, it was possible to image the main periodontal structures. The ultrasound measurements showed better repeatability than either of the other two methods (repeatability coefficient: 0.44 mm for ultrasound, 0.93 mm for transgingival probing and 0.6 mm for direct measurements). Also, ultrasound was in better agreement with direct, open probing measurements (0.004 +/- 0.58 mm) than transgingival probing with direct measurements (0 +/- 0.7 mm).

CONCLUSIONS

Ultrasonography provides a highly accurate and repeatable technique for periodontal assessment in this model.

Position Paper: Diagnosis of Periodontal Diseases

At the present time, the diagnosis and classification of periodontal diseases are almost entirely based on traditional clinical assessments. Supplemental quantitative and qualitative assessments of the gingival crevicular fluid and subgingival microflora can potentially provide useful information about the patient's periodontal disease. In certain situations, these supplemental risk-assessment tests may be particularly valuable in establishing the endpoint of therapy prior to placing patients on a periodontal maintenance program. Although the clinical utility of none of these tests has been validated, their further development is warranted. A genetic test for susceptibility to periodontitis has become commercially available. How best to use this and future host-based tests in clinical practice remains to be determined. Probing depth and clinical attachment loss measurements obtained with periodontal probes are practical and valid methods for assessing periodontal status. Computer-linked, controlled-force electronic periodontal probes are commercially available and are currently in use by some practitioners. Many of the logistical problems associated with subtraction radiography are being overcome and this powerful diagnostic tool may soon come into widespread use. Future developments in this and other imaging techniques are likely to have a profound effect on our approach to the diagnosis of periodontal diseases.

Clinical versus statistical significance as they relate to the efficacy of periodontal therapy

BACKGROUND

The author discusses the shortcomings of using statistical significance testing as a method to infer that results of periodontal clinical trials are clinically meaningful. To compensate for these deficiencies, he also identifies criteria and periodontal parameters that can be used to reflect clinically significant outcomes.

TYPES OF STUDIES REVIEWED

The author searched the medical and dental literature to identify commentaries that addressed the problems associated with interpreting statistical significance testing, or hypothesis testing, and defining clinical significance.

RESULTS

The limitations of statistical significance testing related to identifying clinically significant changes include failure to indicate if the detected differences between variables in test and control groups are large or important. After reviewing various definitions of the term "clinical significance," the author reviews and proposes a comprehensive working definition of it. Regarding the efficacy of periodontal therapy, he delineates the advantages and limitations of specific criteria (such as absolute values, cut points) that can be used to define clinical significance.

CLINICAL IMPLICATIONS

The author suggests that clinically significant results should be defined before initiating a study and statistical significance testing should be used to validate that findings did not occur by chance. This would help place the importance of clinical data into perspective, and it would enhance clinicians' ability to select the most appropriate therapies for particular sites in periodontal patients.

Periodontal terminology revisited

The body of knowledge that was the basis of the science and therapy of periodontics can be found in the literature of the 1950s and 60s. This information conveniently was presented in various textbooks. The evolution of research utilizing histochemistry and electron microscopy, along with disciplined clinical studies, has resulted in an exponential increase in information. A by-product of this worldwide effort is confusion resulting from the misuse and interchangeable application of terms disregarding the definitions originally accepted. Even with workshops designed in part to arrive at consensus to preclude confusion, the literature is replete with misleading use of nomenclature. The lack of attention to the appropriate use of terms is, at best, confusing to the student, researcher, and clinician. In the worst case, it may result in poor performance on examinations and improper evaluation of techniques and materials. Many periodontal terms are used inappropriately or are not completely understood, probably because these words have not been adequately described in the literature. Some of the more commonly used and confused terms will be discussed using literature to support the definitions.

Periimplant probing: positives and negatives

Periodontium in normal dentition is not as it is surrounding an implant area. Thus, periodontal probing with normal dentition is not similar to periimplant probing. The periimplant probing protocol should be different from periodontal probing because of inherent anatomical differences. The aim of this paper is to review the topics related to periimplant probing and to draw inferences to develop a periimplant probing protocol.

Quantification of gingival edema using a new 3-D laser scanning method

OBJECTIVES

The aim of the study was to investigate the suitability of measuring volume differences in the gingival tissue for monitoring changes in the inflammatory status of the gingiva.

MATERIALS AND METHODS

Data for this investigation were obtained from a mouthrinse evaluation which was performed as a 4-week, double-blind, placebo-controlled, cross-over study in which localised experimental gingivitis was induced. 24 volunteers were enrolled in the study. Only the data from the placebo period of each subject were used in the current investigation. During the plaque accumulation periods, plaque guards were worn during routine performance of oral hygiene measures to prevent any plaque removal from the experimental area (1st and 2nd premolars and molars in one upper quadrant). Clinical examinations with assessment of plaque and gingivitis were performed on days 0, 4, 7, 14, 21, 28 and 42. Volume differences in the gingival papillae were determined between day 0 and days 21, 28, and 42, and between days 28 and 42 by taking measurements from replicas of the respective clinical situations using a 3-D laser scanner and reference-free automated 3-D superimposition software. Data were analysed with the Wilcoxon signed ranks test.

RESULTS

Plaque accumulation in the experimental area resulted in a highly significant increase (p<0.001) of inflammation of the gingival papillae. The mean (standard deviation) papillary GI at baseline was 0.23 (0.34) as compared to 1.22 (0.27) and 1.2 (0.31) on days 21 and 28, respectively. The mean increase in volume of all papillae as compared to baseline was 25,478 micrometer3 after 21 days and 24,210 micrometer3 after 28 days. After resuming a normal oral hygiene regimen, mean volume of the papillae decreased between days 28 and 42 by 19,250 micrometer3.

CONCLUSION

With this novel method, gingival papillary edema can be quantified in vivo from replicas of the clinical situation.

Practical periodontal screening and diagnosis

The differences in approach between screening for and diagnosis of periodontal diseases are highlighted. The Periodontal Screening and Recording procedure is discussed in terms of its evolution and current application. For patients screened and found to have more advanced periodontal problems a panoramic dental radiograph with restricted supplemented periapicals are recommended. A comprehensive clinical periodontal examination should be performed for these patients, but it is argued that this may be performed after the initial hygiene phase of treatment. In establishing a diagnosis it is suggested that attention be paid to possible risk exposures. Newer, non-anatomic diagnostic procedures are discussed in principle and it is concluded that these do not have a practical application at present.

Indices to measure gingival bleeding

Gingival bleeding is an objective, easily assessed sign of inflammation that is associated with several periodontal diseases. Many bleeding indices have been devised; some assess bleeding as simply present or absent, whereas others use grading in an attempt to assess severity of bleeding. The choice of which index to use depends on whether the purpose is an epidemiological survey, a clinical study, diagnosis and treatment, or patient motivation. Bleeding may be elicited manually with toothpicks, dental floss or a periodontal probe, but a controlled-force probe, although more expensive, causes less trauma and less false-positive bleeding from healthy tissues. As a predictor of periodontal disease progression, bleeding on probing has low sensitivity owing to a high frequency of false-positive responses, but has high specificity in that failure to bleed indicates health. There is evidence that smokers have less, or delayed, gingival bleeding when compared with non-smokers; therefore smoking needs to be controlled for in studies of gingival bleeding. Measurement of gingival bleeding tendency should be an integral part of a comprehensive oral examination. In clinical practice, the use of a graded bleeding index is more likely to identify sites that are at risk of further destructive activity. For monitoring individual patients, both for response to initial therapy and during maintenance, a modified Sulcus Bleeding Index (mSBI) with three bleeding scores is recommended in preference to dichotomous scoring of bleeding.

Suitability of gingival indices for use in therapeutic trials. Is bleeding a sine qua non?

A number of gingival indices have been described which include visual and invasive components, either separately or in combination. In selecting indices for use in gingivitis therapeutic trials, some investigators maintain that only invasive indices should be used, since indices that include a bleeding-on-provocation component are deemed to be the most objective. Other investigators, however, maintain that non-invasive indices are the more appropriate insofar as invasive procedures will not only disrupt the plaque at the gingival margin, but could also mildly traumatize the tissue and present an impediment to assessing examiner standardization and reproducibility. This paper discusses these aspects of gingivitis evaluation. The data indicate that all validated indices, whether invasive or non-invasive, have some degree of both objectivity and subjectivity. Therefore, the selection of an appropriate index will depend upon the ability of a given index to achieve the objectives of the clinical trial in which it is to be utilized.