Microcirculatory dynamics in experimental human gingivitis

Gingival blood flow before, during, and after clenching, measured by laser Doppler blood flowmeter: A pilot study

INTRODUCTION

This study aimed to investigate the effects of the strong occlusal force on the hemodynamics of gingival microcirculation.

METHODS

Eleven adult volunteers with healthy periodontium and normal occlusion participated in this study. Using a noncontact laser Doppler flowmeter placed at the attached gingiva and the interdental papilla of the maxillary first premolar, changes in gingival blood flow (GBF) were examined during and after clenching.

RESULTS

When the strong occlusal pressure was applied on the maxillary first premolar by clenching, GBF in the attached gingiva on the buccal side decreased significantly compared with the resting GBF, with medians of 2.3 mL/min/100 g and 5.4 mL/min/100 g, respectively (P <0.05). After the release of the maximum clenching, GBF recovered immediately and transiently increased to a median of 2.4 mL/min/100 g, showing a significant difference to the resting GBF (P <0.05). In contrast, in the interdental papilla, no significant change in GBF was found by clenching.

CONCLUSIONS

Ischemia of the buccal attached gingiva associated with strong clenching may be due to compression of the vascular network of the periodontal membrane. Through reactive hyperemia resulting from the release of clenching, it is possible not only that blood flow will be restored to the tissue but that the tissue itself may be damaged by the reperfusion. During active orthodontic treatment, it is suggested that occlusal management to prevent occlusal trauma is important to avoid detrimental effects on periodontal tissues.

Temporal and dynamic changes in gingival blood flow during progression of ligature-induced periodontitis

OBJECTIVES

To evaluate temporal changes in gingival blood flow (GBF) during progression of periodontitis in rats using a laser Doppler flowmeter (LDF) approach and to characterize morphological and biochemical features in the periodontium associated with GBF.

MATERIALS AND METHODS

Forty-two Wistar rats were divided into a ligature-induced periodontitis group and a control group. To induce periodontitis, ligatures were tied around maxillary first molars bilaterally. GBF was measured in palatal gingiva at pretreatment and following ligature placement after 30 min, 1, 3, 7, 14, 21, and 28 days using LDF with a non-contact probe. Bone loss and gene expression in gingival tissues were assessed using micro-computed tomography (μCT) and quantitative polymerase chain reaction (PCR), respectively. Immunostaining for vascular endothelial growth factor (VEGF) in the maxilla was also histologically evaluated.

RESULTS

GBF in the ligature group increased significantly compared with the control group 30 min after ligation. However, on days 3 and 7, GBF decreased in the ligature group. Also, after day 10, there was no difference in GBF between groups. The levels of alveolar bone loss, gene expression (interleukin-6, cluster of differentiation-31, VEGF-A, and lymphatic vessel endothelial hyaluronan receptor-1), and immunostained VEGF-positive vessels correlated well with changes in GBF. CONCLUSION PROGRESSION OF PERIODONTITIS: In rats was associated with a triphasic pattern of GBF, consisting of a short initial increase, followed by a rapid decrease, and then a gradual plateau phase.

Microcirculation and somatosensory profiling of patients with periodontitis: a preliminary case control report

OBJECTIVES

The purpose of this preliminary study was to explore blood microcirculation and somatosensory profiles in periodontitis patients before and after non-surgical periodontal therapy.

MATERIALS AND METHODS

Twenty patients (10 men and 10 women, 20 to 30 years old) and 20 age- and gender-matched healthy controls were included. Non-surgical periodontal therapy was performed for all patients. Clinical examination including pocket probing depth (PPD), clinical attachment loss (CAL), and bleeding on probing (BOP) were performed at baseline (BL), 1 week (1W), and 4 weeks (4W) after non-surgical periodontal therapy on 6 sites of tooth 32 and 42. Laser Doppler flowmetry (LDF) and quantitative sensory testing (QST) were applied at the attached gingiva of tooth 32 and 42 at BL, 1W, and 4W after non-surgical periodontal therapy. Data were analyzed with a two-way mixed-model of ANOVA.

RESULTS

The PPD, CAL and BOP significantly improved after non-surgical periodontal therapy (p < 0.001). Periodontitis patients demonstrated a higher tissue microvascular blood cell concentration (p = 0.015) and a significant gain in thermal (p = 0.037) and mechanical (p = 0.003) somatosensory function compared to controls. After non-surgical periodontal therapy, the flux (p = 0.002) and speed (p = 0.008) of blood flow decreased significantly and thermal (p = 0.029) and mechanical (p < 0.001) somatosensory function were reversed.

CONCLUSION

Gingival microcirculation and somatosensory function seem impaired in patients with periodontitis and are reversed following non-surgical periodontal therapy.

CLINICAL RELEVANCE

LDF and QST may be appropriate tools to further characterize gingival inflammation and treatment responses in periodontitis.

Adjunctive effects of laser therapy on somatosensory function and vasomotor regulation of periodontal tissues in patients with periodontitis: A randomized controlled clinical trial

BACKGROUND

The purpose of this prospective study was to compare the changes in periodontal somatosensory function and microcirculation in patients with periodontitis following initial treatment with scaling and root planing (SRP) with or without adjuvant laser therapy.

METHODS

Twenty-four patients suffering from periodontitis were recruited and randomly allocated into a split-mouth design to either SRP combined laser therapy side (test side) or SRP only side (control side). All treatments were performed by the same investigator at a single visit. Laser Doppler Flowmetry (LDF) and Quantitative Sensory Testing (QST) were performed at baseline (W0), 1 week (1W), 2 weeks (2W), and 4 weeks (4W) after treatment on both sides of the attached gingiva of the maxillary lateral incisor. Clinical examination including probing depth (PD) and bleeding on probing (BOP) was performed at W0, 2W, and 4W on both sides. Data were analyzed with two-way analysis of variance.

RESULTS

PD and BOP significantly improved after treatment (P <0.001). LDF values were significantly decreased on both sides at all follow-up time points (P <0.001), temperature was increased only on the test side (P = 0.017) whereas there was no significant change on the control side (P = 0.792). Significantly less sensitivity was observed for all QST parameters (P <0.030) except for warmth detection after treatment.

CONCLUSION

Adjunctive use of laser therapy did not provide any significant clinical advantage or additional effects on the recovery of periodontal somatosensory function or gingival microcirculation in the present study.

The use of laser Doppler flowmetry to evaluate oral soft tissue blood flow in humans: A review

The objective of this work is to define the conditions for improving the use of laser Doppler flowmetry (LDF) and to determine the limits for the use of this technique. This article systematically reviews the literature on the evaluation of oral soft tissue blood microcirculation by LDF. We analysed the available literature through October 2016 using the database resources Medline/PubMed, the Cochrane Oral Health Group Specialist Trials Register and the ISI Web of Knowledge. Several points emerged from this literature review The use of LDF involves specific constraints; however, the influence of different factors (temperature, tobacco, pressure etc.) must be adequately controlled when using LDF. LDF measurements of soft tissue within the oral cavity vary depending on the anatomical site. In dentistry, LDF can be used to track healing progress in periodontal surgery and to diagnose vascular flow changes in the connective tissue of mucosae covered by a removable prosthesis at an early stage prior to the onset of clinical inflammation signs.

Doppler flowmetry as a tool of predictive, preventive and personalised dentistry

Periodontal lesions are considered a major problem in the global burden of oral diseases due to their high frequency and negative impact on quality of life. Periodontal inflammation is accomplished by a breakdown of microcirculatory function. Early detection of gingival microvessel dysfunction helps diagnose and prevent the progression of initial periodontal pathology. Doppler flowmetry is a useful tool in the diagnosis, monitoring, prognosis and management of periodontal patients which allows access not only of gingival blood flow but also of pulpal microcirculation. Doppler flowmeters might help to realise the ultimate target of predictive, preventive and personalised periodontology tailored with respect to the particular patient. This article highlights the main working principles of laser Doppler flowmeters and the ultrasonic Doppler flowmeters. The advances in blood flow measurement by ultrasonic flowmetry are discussed.

Pulpal blood flow changes in abutment teeth of removable partial dentures

The purpose of this study was to investigate the effect of tooth supported (TSD) and tooth-tissue supported (TTSD) removable partial denture wearing on pulpal blood flow (PBF) of the abutment teeth by using Laser Doppler Flowmeter (LDF). Measurements were carried out on 60 teeth of 28 patients (28 teeth and 12 patients of TTSD group, 32 teeth and 16 patients of TSD group) who had not worn any type of removable partial dentures before, had no systemic problems and were non smokers. PBF values were recorded by LDF before insertion (day 0) and after insertion of dentures at day 1, day 7 and day 30. Statistical analysis was performed by student t test and covariance analyses of repeated measurements. In the group TTSD, the mean values of PBF decreased statistically significantly at day 1 after insertion when compared with PBF values before insertion (p<0,01). There was no statistically significant difference among PBF mean values on 1st, 7th and 30th day. However, in the group TSD, there was no statistically significant difference among PBF mean values before insertion and on 1st, 7th and 30th day. In other words, PBF mean values in group TSD continued without changing statistically significant on 1st, 7th and 30th day.TTSD wearing may show negative effect on the abutment teeth due to decreasing basal PBF.

T1 relaxation time and magnetic resonance imaging of inflamed gingival tissue

OBJECTIVES

The aim of this study was to evaluate the use of MRI as a non-invasive method for the characterization of the inflammation and healing processes in periodontal tissues.

METHODS

For the in vitro study, 99 gingival samples were collected during periodontal surgical treatment and T1 relaxation time measurements were performed and correlated to the probing depth measurements recorded at the collection sites. For the in vivo study, a group of eight patients with moderate to advanced periodontal disease was examined with pre-contrast and Gd-DTPA contrast-enhanced T1 weighted MRI both before and 3 months after non-surgical periodontal therapy. On the MR images of the 8 patients, 53 regions of interest (ROIs) were selected. For each ROI, the ratio between post- and pre-contrast signal intensity (RSI) was calculated and used as a measure for the degree of inflammation.

RESULTS

The in vitro T1 relaxation times measurements of gingival samples showed an increase in relaxation times with the increase of probing depth at the sites of tissue removal. The in vivo studies demonstrated that the reduction of inflammation and probing depth in gingival tissues after non-surgical periodontal therapy correlates with a decrease of RSI in T1 weighted MR images. The non-invasively obtained data provide the characteristic ratio U, which shows that two distinct types of inflammation occurred in the examined group of patients.

CONCLUSIONS

The results of MRI provide a new possibility to characterize the type and healing process of periodontal inflammation.

Evaluation of the marginal gingival health using laser Doppler flowmetry

The purposes of this study were to compare the gingival blood flow (GBF) in test sites (teeth retaining fixed partial dentures) and control sites (contralateral natural teeth) and investigate whether there is any relationship between clinical indices and GBF values. Twelve healthy subjects (6 females and 6 males) aged 20 to 54 years were enrolled this study. The GBF was measured from the middle point of the marginal gingiva in the test and control sites using laser Doppler flowmetry (LDF). Additionally, plaque index, gingival index and probing depth measurements were recorded. Statistically significant difference (p<0.05) was found between the test and control sites for marginal GBF. In contrast, no significant difference (p>0.05) was found between test and control sites with respect to the clinical indices, except for plaque index. The findings of this study suggest that there is a significant relation between resin-bonded fixed partial dentures with margins located subgingivally and marginal GBF. Clinical indices are helpful to collect information about the clinical health status of gingival tissues, but GBF is a good tool to measure gingival tissue blood flow and assess periodontal health. In conclusion, laser Doppler flowmetry can be used together with clinical indices to evaluate the marginal gingival health.

Dose-related effects of epinephrine on human gingival blood flow and crevicular fluid production used as a soaking solution for chemo-mechanical tissue retraction

STATEMENT OF PROBLEM

Epinephrine is a frequently used agent for impregnation of the retraction cord. Removal of retraction cord from the gingival sulcus has been shown to elicit a hyperemic response that could be prevented by epinephrine. However, the epinephrine may cause local or systemic adverse effects in the circulation.

PURPOSE

The aim of this study was to identify the effective concentration of epinephrine that may prevent the hyperemic response and consequently keep the crevicular fluid production low after cord removal without local or systemic side effects.

MATERIAL AND METHODS

Seventeen healthy human subjects had their crevicular fluid volume and gingival blood flow measured by Periotron and laser Doppler flowmetry, respectively, before and after cord removal at the left maxillary central incisor. The right maxillary incisor served as the control. Retraction cords were presoaked in physiological saline or various concentrations (0.001%, 0.01%, and 0.1% w/v) of epinephrine solution. Double repeated-measures analysis of variance with the Fisher Least Significant Difference post hoc test was used to statistically evaluate the blood flow values (mean +/- SE, alpha=.05), and the Wilcoxon matched pair test was used for crevicular fluid values, given as median (25-75 percentile, alpha=.01).

RESULTS

In the saline group, cord removal resulted in elevated blood flow (140% +/- 11%, P<.001) and crevicular fluid production (300% (130%-470%), P<.05). After cord removal in the 0.01% and 0.1% epinephrine groups, blood flow remained low for the measured period (43%-70%, P<.05). The crevicular fluid production transiently increased in the 0.01% epinephrine group (170% (140%-380%), P<.001), but then returned to baseline level and remained low as for the 0.1% group. No systemic vascular effect was detected in any groups.

CONCLUSION

The prolonged increase in crevicular fluid production and hyperemic response after cord removal can be prevented by application of 0.01% epinephrine solution without systematic changes.

Local gingival blood flow at healthy and inflamed sites measured by laser Doppler flowmetry

BACKGROUND

This investigation aimed to: 1) develop a method to obtain reproducible laser Doppler flow readings (LDFRs) at the gingiva of the maxillary front teeth; 2) evaluate regional gingival blood flow (GBF) in healthy gingiva by laser Doppler flowmetry; 3) compare hand-held LDFR (H-LDFR) with splint LDFR (S-LDFR); and 4) monitor changes in GBF in experimental gingivitis (EG) and chronic gingivitis (CG).

METHODS

The LDFR, gingival index (GI), and plaque index (PI) were measured at 13 gingival sites (teeth #6 to #11) in 10 healthy volunteers (five males and five females), 23 to 34 years of age, over a period of 12.5 +/- 3.27 days employing a partial-mouth EG model and in 11 patients (three males and eight females), 20 to 63 years or age, with CG. LDFRs were obtained by S-LDFR or H-LDFR.

RESULTS

H-LDFRs were significantly higher than S-LDFRs (P <0.05). All EG subjects developed gingivitis (PI: 2.77 +/- 0.23; GI: 1.5 +/- 0.53). EG-LDFRs at diseased sites increased slightly but not significantly over the study period. All CG-patients had high plaque and inflammation scores (PI: 2.8 +/- 0.2; GI: 1.63 +/- 0.78). CG-LDFRs at sites with GI >1 were significantly higher than LDFRs at healthy sites (P <0.05). CG-LDFRs were significantly higher than EG-LDFRs at sites with a comparable GI (P <0.05).

CONCLUSIONS

LDFRs are positively correlated with the degree of gingival inflammation. GBF demonstrated significant differences in EG and CG. Modifications of the probe are needed to enhance its clinical applicability in clinical research of periodontal diseases.

Gingivitis and Periodontitis as Antagonistic Modulators of Gingival Perfusion

BACKGROUND

We explore the possible association between the extent of gingivitis or periodontitis and an index of gingival microvascular perfusion response to compression of alveolar mucosa, called the gingival perfusion index (GIPI).

METHODS

A cross-sectional analytical study was done in a sample of 60 adults, including healthy and non-insulin-dependent diabetic subjects of either gender, with teeth in the anteromandibular sextant with or without gingivitis and with or without periodontitis at the lower-left lateral incisor (LLLI). A sample was selected by convenience non-probability sampling. Gingival perfusion was evaluated at labial LLLI attached gingiva. Two perfusion recordings were done 5 minutes apart, each one consisting of a 40-second control phase, a 22-second compression phase, and a 40-second postcompression phase. LLLI alveolar mucosa was compressed with a wood-mounted cotton swab until reaching about one-fifth of the control perfusion value. GIPI was used as response dependent variable. The gingival index and probing depth were used as measures of the extent of gingivitis and periodontitis, respectively.

RESULTS

By analysis of covariance and multiple regression analysis, it was found that only the probing depth (negatively) and gingival index (positively) predicted GIPI (R(2) adjusted = 0.5194, P <0.0001).

CONCLUSIONS

The data strongly suggest that, at least in the studied sample, gingivitis and periodontitis operate as antagonistic modulators of gingival perfusion. The major practical implication of our findings is that an increase or decrease in this index (GIPI) at a given attached gingiva site could indicate, respectively, the clinical predominance of gingivitis or periodontitis in such a site.

The lamp effect of laser Doppler flowmetry on teeth

The aim of this study is to analyse the intra and extracoronal scattering of laser light. Twelve vital teeth from 12 volunteer individuals (aged 22-29 years) were used. The camera removing the charge coupled device's infrared cut filter was used for imaging the laser Doppler flowmetry light during pulpal blood flow measurement. When the obtained photos were analysed, it was seen that the laser beam caused the tooth to shine like a lamp and it also illuminated the tissues inside the mouth (tongue, lips, adjacent teeth, etc.). As a result, it was shown that when the necessary cautions were not taken, the laser could scatter all around the tissues surrounding the tooth. Because of the conductive characteristic of the fibre and the optical characteristics of the tooth, we think that the beam is inevitably scattered onto the tissues outside the pulp and together with the isolation of the gingiva, crown should be isolated, as well.

Arachidonic Acid-Induced COX-1 and COX-2-Mediated Vasodilation in Rat Gingival Arterioles In Vivo

The roles of cyclooxygenase (COX) and prostaglandins (PGs) in the regulation of vasoreactivity of rat gingival arterioles in vivo were evaluated by sing an intravital microscope. The superfusion of indomethacin (a nonselective COX inhibitor) or SC-560 (a selective COX-1 inhibitor) onto the gingiva significantly constricted the arterioles, though NS-398 (a selective COX-2 inhibitor) did not affect the diameter of the arterioles. The SC-560-mediated constriction of the arterioles was completely reversed by an additional treatment with arachidonic acid (AA). The superfusion of AA, beraprost-Na (an analogue of PGI2) or PGE2 onto the gingival significantly dilated the arterioles dose-dependently. The AA-induced dilation of the arterioles was significantly reduced by the treatment with SC-560 or NS-398. The expression of COX-1 and COX-2 were positive in the endothelium, but not the smooth muscles, of the arterioles. The expression of PGE synthase (PGES) was found only in the smooth muscles, but not the endothelium, of the arterioles. Neither the endothelium nor the smooth muscles of the arterioles expressed PGI synthase (PGIS). These findings suggest that the COX-2-mediated PG cascade may collaborate with the COX-1 pathway in the regulation of arteriolar myogenic activity in rat gingiva in the case of the supply of a large amount of AA.

Quantifying labial blood flow using optical Doppler tomography

OBJECTIVES

Changes in the oral microvasculature occur in a variety of diseases. Optical Doppler tomography (ODT) combines laser Doppler flowmetry with optical coherence tomography (OCT) to produce high-resolution tomographic images of biological tissues that also detect the velocity and direction of blood flow. The objective of this study was to determine the feasibility of ODT to image labial blood flow. A prototype ODT imaging system was constructed that characterized and measured labial blood flow in healthy subjects.

MATERIALS AND METHODS

A prototype ODT instrument was constructed using a diode light source with a central wavelength of 1300 nanometers, a 40-nanometer spectral width and 2.4 microwatts output power. To verify the accuracy of the system, the flow rates of a phantom material (Intralipid) pumped through a capillary tube at various speeds was measured. To evaluate the clinical feasibility of the ODT prototye, the mucosal aspect of the upper and lower lips at the midline was imaged in 9 healthy volunteers. The sample arm of the instrument consisted of a fiberoptic probe with a 2-mm in diameter polished glass lens attached to the end. The probe was placed approximately 3 mm from the mucosal surface of the lip and oriented perpendicular to the surface. A motorized translation stage moved the fiber in a superior to inferior direction while the subject's head was stabilized by placing the chin into a chin rest. Imaging time for a 12-mm x 2.5-mm scan was approximately 64 seconds.

RESULTS

The phantom experiments revealed that accuracy of this novel ODT prototype to measure flow was within 5%. In vivo labial blood flow velocity ranged from 11.8 to 43.1 mm/second in the upper lip and 8.2 to 53.2 mm/second in the lower lip. There were no statistically significant differences between flow rates in the upper and lower lips. OCT images and Doppler velocity signals were successfully integrated producing in vivo images of labial blood in all of the subjects (15 images). The resulting cross-sectional images revealed microscopic details of labial structures and, to the best of our knowledge, are the first ODT images of the labial microvasculature.

CONCLUSIONS

The results of this in vivo study prove the feasibility of ODT to quantify labial blood flow and produce high spatial resolution images specifically localizing vessels anatomically. ODT provides both flow speed and flow direction information. ODT is noninvasive and offers the advantages of high volumetric flow sensitivity.

Effect of gingiva on laser doppler pulpal blood flow measurements

The purpose of this study was to evaluate the effect of labial and palatinal gingiva on laser Doppler pulpal blood flow measurements. Twenty upper central incisor teeth determined to be vital from 20 volunteers were included into the study. To stabilize the probe, a laboratory-made acrylic splint positioned the probe labially on the cervical third of the tooth crown. We collected measurements without any gingival covering, and under three conditions: after application of an opaque paste on the labial gingiva, the palatal gingiva, or both the labial and palatal gingiva. The measurement values decreased 46% when there was opaque paste on labial gingiva, 10% on palatinal gingiva, and 63% on both. The decrease in the values when there was an opaque paste on palatinal gingiva was not statistically significant (p > 0.05). The differences between all other groups were statistically significant (p < 0.05). In these measurements, the contribution of labial gingiva to laser Doppler pulpal blood flow measurements is more than that of palatinal gingiva.

Modulation of clinical expression of plaque-induced gingivitis. II. Identification of "high-responder" and "low-responder" subjects

AIM

The aims of this study were to validate a randomized, split-mouth, localized experimental gingivitis model and to identify subjects with different gingivitis susceptibility.

MATERIAL AND METHODS

In each of 96 healthy subjects, one maxillary quadrant was randomly assigned as "test" (experimental gingivitis) and the contralateral quadrant as "control". Plaque index (PlI), gingival index (GI), gingival crevicular fluid volume (GCF), and angulated bleeding score (AngBS) were recorded in both quadrants at days 0, 7, 14, and 21. Cumulative plaque exposure (CPE), i.e. PlI over time, was calculated. Day-21 GCF was standardized according to CPE, and residuals of GCF on CPE were calculated. Two subpopulations were then defined, based on upper and lower quartiles of GCF-residual distribution and were, respectively, identified as "high-responder" (HR; n=24) and "low-responder" (LR; n=24).

RESULTS

At test quadrants, all parameters significantly increased throughout the trial, while in control quadrants, PlI, GI, and AngBS remained low. Significant differences were noted between test and control quadrants on days 7, 14, and 21 for all parameters. Significant increases in GI, AngBS, and GCF were observed in test quadrants over the course of the study in both HR and LR groups. Significant differences were noted between HR and LR groups for all gingivitis parameters on day 21 in test quadrants, without any significant differences in PlI or CPE between the groups.

CONCLUSIONS

We identified two subpopulations characterized by significant differences in clinical parameters of plaque-induced gingival inflammation, despite similar amounts of plaque deposits and plaque accumulation rates.

Identification and consequences of distinct Löe-Silness gingival index examiner styles for the clinical assessment of gingivitis

BACKGROUND

In clinical studies, gingivitis is most frequently assessed by the Löe-Silness gingival index (GI). The objective of this work was to develop an understanding of how clinicians experienced with GI differ with respect to how they apply GI and to assess the impact of different examination styles on statistical outcomes and magnitude of treatment differences.

METHODS

A method was developed to mathematically relate the average GI score and degree of bleeding observed for a subject. Graphical analyses were used to profile examiner styles with respect to using the GI index. A prospective single-center, examiner-blind study comparing the effects of a staggered prophylaxis on gingivitis was then conducted, where a difference in gingivitis was created between two balanced groups by providing subjects a prophylaxis at two staggered time points. Subjects were assigned to one of two cohorts; within each cohort, group 1 subjects received a dental prophylaxis following the baseline examination and group 2 subjects received a dental prophylaxis 8 weeks later. Five to 7 days after the group 2 prophylaxis, all subjects were examined for GI. Twelve experienced clinicians participated.

RESULTS

Retrospective analyses indicated the presence of distinct examiner styles which are based on the frequency that a given GI score (0, 1, 2, or 3) is measured by a clinician. In the prospective study, all 12 examiners observed statistically significant differences between the prophylaxis treatment groups at the final visit for both mean number of bleeding sites and mean GI; the magnitude ranged from 21.5% to 84.6% for mean number of bleeding sites and 9.4% to 39.2% for mean GI. There were 4 distinct styles employed by these experienced clinicians.

CONCLUSIONS

Varying examiner styles impact the structure of resulting data. Importantly, the implementation of arbitrary thresholds (e.g., 20%) regarding percent treatment differences between groups as a guideline for judging the clinical significance is scientifically unsupported. A more scientific criterion in the field of gingivitis clinical testing would be the independent demonstration of statistical superiority compared to a negative control and/or a demonstration of similar or superior efficacy to clinically proven positive controls. In addition, interexaminer calibration is a mechanism that can be utilized to minimize the impact of different examiner styles in clinical settings involving more than one examiner.

Microassay for the detection of elastase activity in the gingival crevice

BACKGROUND, AIMS

A new microassay for the detection of elastase activity (EA) in gingival crevicular fluid (GCF) has been established. GCF was collected with Periopaper strips and quantified in a Periotron.

METHODS

Enzyme activity was measured in a microtiter plate reader, using a fluorometric assay. To ensure quality and precision of the assay, recovery rates were determined at different activities with a recovery of >90%. In a 2nd step, stability of the enzyme was investigated during storage at room temperature, +4 degrees C, -22 degrees C, -88 degrees C. GCF samples retained elastase activity of almost 100% after a storage of 3 days at -22 degrees C. In a group of 12 healthy volunteers, elastase activity was assayed throughout an 18 day experimental gingivitis protocol.

RESULTS

Median activity increased from 481 microU/microl at baseline to 1444 microU/microl at day 18, which was accompanied by the development of the signs of gingivitis. The increase of EA during the experimental phase of the study was highly significant (p<0.001) and correlated well with the increasing severity of gingivitis.

CONCLUSION

The data suggest that elastase activity in GCF is an excellent quantitative measure of gingival inflammation.

The effects of thermal and mechanical stimulation on blood flow in healthy and inflamed gingiva in man

The purpose of this study was to compare the state of the microcirculation in healthy gingiva with that in untreated, inflamed gingiva in humans. Reflection photoplethysmography (RP) was used to record blood flow from 13 clinically healthy, attached gingival sites in seven adults and 11 inflamed sites in seven patients. Changes in the pulse amplitude of the RP signal were measured before and after application of thermal (cold and hot water) and mechanical (brushing) stimuli to the gingiva. Hot water and brushing, but not cold water, produced a significant increase in the pulse amplitude in healthy gingiva (p < 0.05, Friedman analysis and Student-Newman Keuls test). None of the stimuli produced a significant change in inflamed gingiva. In neither group of participants was there a significant correlation (Spearman rank correlation coefficient) between vascular responsiveness and age. The results indicated that vasomotor control may be impaired in inflamed gingiva.

Gingival microcirculation response to tooth brushing measured by laser Doppler flowmetry

This study quantified changes in blood flow following tooth brushing, using laser Doppler flowmetry (LDF). Twenty subjects had polysiloxane stents fabricated with openings to permit placement of the LDF probe on the mesial papillae of 6 teeth. Probing depth, plaque index, and gingival index were recorded and subjects instructed in brushing. LDF initially recorded a 30 second baseline blood flow. The stent was removed and subjects brushed the site for either 3 or 10 seconds. The stent was repositioned and recordings again taken, followed by a control reading. The process was repeated 4 weeks later. Correlations between baseline and control readings were 0.585 (P < 0.001) at the first visit, and 0.654 (P < 0.001) at the return visit. The mean control blood flow was 156.4 perfusion units. The 3 and 10 second brushing increased the mean value 22.6 units and 21.2 units respectively (both P < 0.001). Tooth brushing for both 3 and 10 seconds significantly increased gingival blood flow in the papillary gingiva of healthy individuals.