Factors associated with occurrence and reversibility of connective tissue attachment loss.

Marginal periodontitis appears to be site-specific, demonstrates rapid bursts of connective tissue attachment destruction, and may, at times, repair spontaneously. The present study was undertaken to investigate associations between bacterial populations and periodontal destruction parameters within the first 14 days after induction of experimental periodontitis in animals receiving metronidazole. Metronidazole was administered orally to four squirrel monkeys for 17 days at a daily dose of 100 mg/kg body weight. After three days (baseline), marginal periodontitis was induced by tying silk ligatures at the gingival margins of maxillary and mandibular bicuspids and molars. Subgingival bacterial samples were taken and periodontal destruction evaluated at baseline, and 3, 7 and 14 days after ligature placement. Dark-field microscopy was used to quantitate motile forms, spirochetes, straight and curved rods, filaments, cocci and fusiforms. Levels of connective tissue attachment, crestal alveolar bone and the volume of bone were assessed histometrically. Bacterial and histometric parameters were analyzed using analysis of variance. The results indicated that subgingival plaque, prior to induction of periodontitis, consisted primarily of cocci. At three days after ligature placement, cocci were significantly decreased, while straight rods became the predominant bacterial group for the remainder of the study. Spirochetes and motile forms were virtually absent at all time points. Histometric analyses showed significant loss of connective tissue attachment at three and seven days, which was reversed and repaired at 14 days. Factors relating to initiation, potentiation, and reversibility of connective tissue attachment loss are discussed.

Synthetic bioabsorbable barrier for regeneration in human periodontal defects.

Guided tissue regeneration (GTR) may result in the formation of new bone, cementum, and periodontal ligament. The purpose of this study was to assess the efficacy of a resorbable synthetic material, which has been used extensively in general surgery for wound support, to promote GTR. Forty healthy patients with adult periodontitis, each having a Class II furcation defect, participated in the study. After initial therapy, mucoperiosteal flaps were elevated and furcations debrided with hand and rotary instruments. In 20 patients the molar Class II furcation defects were treated with a GTR procedure using the resorbable synthetic material (experimental), and 20 patients received a mucoperiosteal flap debridement procedure without barrier placement (control). Probing depth and attachment level measurements were taken immediately before surgery, at 6 weeks, and 2, 3, 4, 5, and 6 months after surgery. All areas healed uneventfully. Comparison of clinical attachment level measurements indicated significantly greater gain of attachment at sites receiving barriers. Fifteen of 20 Class II furcations in the synthetic barrier group, but only one of 20 in the control group, were converted to Class I defects. Barriers were still clinically detectable at 4 weeks, but were absent at 6 weeks. The synthetic barriers enhanced gain of clinical attachment in human Class II furcation defects.

Nature and attachment of cementum formed under guided conditions in human teeth. An electron microscopic study.

In an attempt at characterizing the nature and attachment of cementum formed under conditions of guided tissue regeneration (GTR) in humans, front teeth from 4 patients aged 42 to 72 years were examined at the electron microscopic level. All teeth were affected by complex periodontitis associated with advanced loss of periodontal support. Roots were surgically planed and notched, but not chemically conditioned. Either the mesial or distal surface of each tooth represented the experimental site and was covered with a biodegradable polyglactin 910 barrier, while the opposite approximal surface served as control. Following 3 months of healing, teeth were removed together with surrounding periodontal tissues including some alveolar bone. These blocks were fixed histologically, decalcified, embedded in epoxy, and sectioned for examination in the scanning (backscatter mode) and transmission electron microscope. Both experimental and control sites disclosed 2 types of regenerative cementum that seemed to be formed by cells resembling cementoblasts. The first type was characterized by a thin fringe of collagen fibrils which were arranged perpendicular to the root surface and appeared mineralized in a zone extending about 1 to 3 microm from the dentin. The second type occurred as thick patches which revealed scattered cementocytes and sheets of collagen fibrils oriented mainly parallel to the root surface, running both circularly and axially. In both situations, a continuous, thin, electrondense layer was interposed between newly formed cementum and preexisting radicular hard tissues. Interdigitation of collagen fibrils from cementum and dentin, such as observed along the natural cemento-dentinal junction, did not occur. Thus, regenerative cementum laid down in humans under guided conditions on previously diseased and planed, but not otherwise treated root surfaces shares some morphologic features with cementum formed during spontaneous repair of root resorptions. However, unlike in the course of such repair, a fibrous attachment of new cementum resembling the natural cemento-dentinal junction does not seem to be regenerated under guided conditions.

Short-term effects of phase I therapy on crevicular cell populations.

The purpose of the present study was to use a novel intracrevicular lavage technique to evaluate short-term effects of phase I therapy on crevicular cell populations. Nineteen patients with untreated advanced adult periodontitis were selected for phase I therapy. One side of the dentition was treated with ultrasonic curets (U), the other side with manual curets (M). Nine months before (-9), immediately prior to (0), and 1 month after treatment (+1) gingival index (GI), plaque index (PI), bleeding index (BI), bleeding on probing (BOP), probing depth (PD), and probing attachment levels (PAL) were measured at all sites in the dentition. Crevicular lavages were obtained from 3 to 4 selected sites per patient at the same time points. Crevicular leukocytes were vital stained with ethydium bromide-fluorescein-diacetate (EB-FDA). The total number of cells and the percentage of vital cells (%) were calculated for each sample. Clinical and lavage parameters obtained from the selected sites were compared between U and M sites, and between pre- and post-treatment values. The results showed that without treatment PAL remained at the same level at both pretreatment time points -9 and -0 (control). At 1 month after treatment there were statistically significant reductions in GI, PI, BOP, and PD (P < 0.001 for each comparison), and a statistically significant gain in PAL from 4.9 to 4.1 mm (P = 0.014). The total number of leukocytes per sample was similar at both pretreatment time points, but numerically reduced at 1 month after treatment. The percent of vital leukocytes was above 74% at both pretreatment time points (control). After treatment these values were below 70%. This reduction was statistically significant (P < 0.002). These results suggest that periodontal phase I therapy leads to shifts in crevicular cell populations.

Cell populations associated with active probing attachment loss.

The purpose of this study was to evaluate the ability of cell populations to differentiate between untreated progressing periodontitis sites (P) and untreated non-progressing sites (NP). Pairs of biopsies were obtained from untreated periodontal patients, one biopsy from a site which had lost probing attachment of 2 mm or more within the previous month, the other biopsy from a non-progressing site. Cell populations were identified on 1 micron sections in a defined connective tissue area at the junctional epithelium. The cell types counted were fibroblasts, mast cells, monocytes/macrophages, polymorphonuclear leukocytes (PMNs), lymphoid cells, plasma cells, endothelial cells, total inflammatory cells, and the total number of cells. The number of fibroblasts, mast cells, monocytes/macrophages, and inflammatory cells, as well as their percentage of the total number of cells, differed significantly between P- and NP-sites. In addition, the actual total counts differed between groups. The difference between groups was more significant for percent fibroblasts than for any other cell type. It appears that cell populations, particularly fibroblast counts, can aid in the histological discrimination between P and NP periodontitis lesions.

In vivo determination of radiographic projection errors produced by a novel filmholder and an x-ray beam manipulator.

Subtraction radiography requires radiographs made with identical projection geometry. The purpose of the present investigation was to develop and evaluate a new in vivo method to measure angular radiographic projection error. This included the development of a system for accurate control of the x-ray beam angulation relative to the intraoral film and the evaluation of the in vivo projection errors (equivalent to the "angular difference" between repeated exposures) produced by the new system. A filmholder, an x-ray beam manipulator, and an aiming device were newly constructed. Reference wires were attached for measuring the projection error on the filmholder and on the 22 bicuspids at the sites of investigation in 16 patients. Two exposures using standardized projection conditions were made of each site. The relative position of the reference wires on the duplicate radiographs was used to calculate the angular difference in the direction of the x-ray beam which occurred between the 2 exposures. Triplicate measurements allowed the determination of measurement error. The angular projection errors were measured in a horizontal and vertical direction. The reference wires allowed determination of the angular projection errors relative to the filmholder, relative to the dentition and the angular error due to the repositioning of the filmholder in the patient's mouth. The average projection errors deviated only slightly from zero. The largest deviation registered was -0.11 degrees. This applies to the horizontal and vertical direction and all relationships. The standard deviations varied between 0.403 degrees and 0.697 degrees. This applies to the standard deviation for all relationships in the horizontal, the vertical, and the oblique directions. The measuring error found from the triplicate measurements had a standard deviation of 0.08 degrees to 0.19 degrees depending on the distance between the reference wires. This new system for controlling in vivo projection errors seems to provide highly standardized radiographs in vivo. The new measuring system proved to be accurate enough to measure the in vivo projection errors between repeated radiographs produced with the new filmholder and x-ray beam manipulator. The in vivo errors produced by the new system are markedly smaller than all in vivo and in vitro errors previously reported in the literature.

Episodic probing attachment loss in humans: histologic associations.

Marginal periodontitis in humans is characterized by episodes of probing attachment loss followed by periods of quiescence. The purpose of the present study was to assess characteristics of the inflammatory infiltrate in periodontal lesions where episodic probing attachment loss had occurred within the previous month. In 10 systemically healthy adult human subjects with untreated advanced periodontitis, probing attachment levels were measured at baseline and every 30 days thereafter for 10 months. Measurements were made at six sites of every tooth using an acrylic onlay as a reference point and a pressure sensitive probe. Sites where double measurements confirmed that probing attachment loss of 2 mm or more had occurred within the previous month were identified (P-sites), as were corresponding contralateral non-progressing sites (C-sites). Biopsies of the supracrestal tissues were taken from these sites, processed, and cut in 1 mu sections for histologic evaluation. Counts of inflammatory cells in standard areas of the sections were compared between P and C sites. The results indicated that 5.04% of 1566 sites under investigation lost probing attachment during the 10-month observation period. Inflammatory cell counts were higher in P-sites as compared to C-sites. P-sites with more than 2 mm attachment loss (P greater than 2 sites) had significantly more inflammatory cells within standard areas at the apical end of the junctional epithelium than non-progressing C-sites (P less than 0.02). There was no significant difference in counts between P-sites progressing 2 mm (P-2 sites) and corresponding C-sites.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo scaling and root planing forces.

The purpose of the present study was to assess the scaling and root planing forces exerted in vivo. Ten dentists and 10 dental hygienists scaled and root planed one aspect of an incisor in an adult patient with untreated advanced periodontitis. During scaling and root planing forces were recorded using a piezo-electric receiver, an electronic transducer, and an analogous writer. The forces were recorded in mA and converted into Newtons (N). The results showed that the mean scaling force applied by dentists was 5.70 N and ranged between 1.01 to 10.35 N. The corresponding values for dental hygienists were a mean of 5.38 N, and a range of 1.52 to 15.73 N. The root planing forces in dentists reached a mean of 4.62 N, and ranged between 0.86 to 8.88 N. For hygienists, these values were 4.58 N with a range of 1.56 to 10.59 N. Negative forces impacting on the periodontal soft tissues were also recorded. They were not present in all therapists, but consistently at work within specific therapists. During scaling these forces reached a mean of -0.40 N in dentists and -0.47 N in dental hygienists. During root planing, these forces were mean -0.59 N in dentists, and -0.81 N in hygienists. There were no statistically significant differences between scaling forces and root planing forces, nor between forces used by dentists and hygienists (P greater than 0.05). However, there were significant differences between the force levels of the individual therapists for all positive forces (P = 0.0001), and for negative forces during root planing (P = 0.0001). The technology and information provided by this investigation may enable studies evaluating clinical effectiveness of scaling and root planing doses.

In vivo scaling and root planing forces in molars.

The purpose of the present study was to assess in vivo scaling and root planing forces in molars of periodontitis patients. Ten dentists and 10 dental hygienists scaled and root planed the mesial and distal aspect of one first molar, using Gracey curets 11/12 and 13/14. Scaling and root planing forces were recorded using a piezo-electric receiver, an electronic transducer, and an analogous writer. The forces were recorded in mV and converted into Newtons (N). Three different types of forces were recorded: positive forces during working strokes and positive and negative forces during preparation of working strokes. Multivariate repeated measures analysis of variance was used to assess differences in force between curet types. The mean positive scaling forces exerted with curet 11/12 were statistically significantly (P = 0.0005) greater than the corresponding forces exerted with curet 13/14 in all therapists. The mean positive root planing forces applied with the curet 11/12 were significantly (P = 0.0008) greater than the forces exerted with curet 13/14. The mean positive interstroke forces did not differ between curet 11/12 and 13/14. The mean negative interstroke forces impacting on the soft tissues exerted with curet 11/12 did not significantly differ from curet 13/14 during scaling and during root planing. Therapists differed significantly among themselves for each type of positive and negative force (P < 0.001 in all cases). These results suggest that the extent of instrumentation given to root surfaces in molars depends more on the therapist and on the molar aspect being treated than on the needs of a specific site.

Time-related changes of in vivo projection errors in standardized radiographs.

Subtraction radiography requires radiographs made with identical projection geometry. Recently a new radiographic aiming device and an x-ray beam manipulator made it possible to repeat radiographic exposures in vivo with small angular errors and to measure the angular errors occurring. The purpose of the present investigation was to study in vivo the measuring error and the angular errors produced by this new method at different time points (0, 6, and 12 months) and to assess the effect of different time intervals between exposures (0, 6, and 12 months). Ten sites were investigated. At each time point 2 exposures were made, resulting in 6 radiographs per site. For each pair of radiographs the measuring errors occurring during analysis and the projection errors were determined for each time point and for each time interval. Friedman's test and t-test were used to evaluate the errors. A difference in the measuring error of the system and in the angular errors at the time points 0, 6, and 12 months could not be detected. A time interval between exposures also did not have an effect on the measuring error. Time did not affect the vertical and horizontal angular errors measured between the radiographs producing the smallest oblique error. A combination of radiographs producing the largest oblique angular error showed an increase of the horizontal and vertical angular errors when the time interval increases. These effects, however, were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical furcation diagnoses and interradicular bone defects.

The purpose of the present study was to assess associations between clinical depth of involved furcations and their bony defect depth. Twelve patients with moderate to advanced periodontitis in molars were recruited for clinical evaluation of furcation involvement by 6 dentists. Two groups of 3 dentists were assigned to the right or left half of the dentition. All dentists assessed the clinical depth of involvement of the furcations using the Ramfjord index (2 mm) in patients 1 through 6, and using the Hamp index (3 mm) in patients 7 through 12. Diagnoses were made with calibrated and uncalibrated Nabers 2 probes. After the clinical assessments the patients received full mouth scaling and root planing. After reevaluation the molars were surgically exposed. During surgery the depth of the bony furcation defects was assessed using horizontal probing and impressions. Clinically assessed depth of furcation involvement was then compared with the surgical measurements. A total of 1,180 clinical furcation diagnoses were available, of which 426 could be surgically evaluated using both the straight probe and the impressions. These evaluations were done in a total of 72 furcations using probe and impressions. For the Ramfjord index, 5% of the clinical degree 1, 40% of the degree 2, and 43% of the degree 3 readings were overestimations. For the Hamp index, 7% of degree 1, 24% of degree 2, and 0% of degree 3 readings were overestimations. These clinical diagnoses were overestimations. Forty-three percent of surgical degree 3 involvements were not recognized when using the Ramfjord index, and 27% when using the Hamp Index. These results suggest that furcation diagnosis is of limited validity.

Root substance removal by scaling and root planing.

The amount of root substance removed by scaling and root planing is largely unknown. The present study evaluated in vitro the root substance loss caused by a defined number of working strokes at known forces. Forty extracted teeth with loss of connective tissue attachment into the middle third of the roots were washed and embedded in plaster, leaving one entire corono-apical tooth aspect exposed. The teeth were reproducibly repositioned in a bench-vise, where a profilometer repeatedly measured root surface levels at the same location. In a standard area of the roots a total of 40 working strokes were applied. Low forces were used in 30 teeth and high forces in 10 teeth. The forces were recorded using a piezo-electric receiver built into the upper shank of the curet. Root substance loss was measured after 5, 10, 20, and 40 working strokes. The results showed that the mean low force used per working stroke across all 40 strokes was 3.04 Newtons for the low forces, and 8.48 Newtons for the high forces. Mean cumulative loss of root substance across 40 strokes was 148.7 microns at low forces, and 343.3 microns at high forces. The mean force per stroke increased slightly across the 40 strokes, while substance removal per stroke decreased. Substance removal per stroke during strokes 1 to 5 was 6.8 microns using low forces and 20.6 microns using high forces. During strokes 21 to 40 mean removal per stroke was 2.3 microns at low forces, and 5.6 microns at high forces. These results suggest that high forces remove more root substance, and loss per stroke becomes less with increasing numbers of strokes.

Effect of metronidazole on development of subgingival plaque and experimental periodontitis.

Active tissue destruction in experimental periodontitis has been positively correlated with subgingival spirochetes and total number of organisms. The present study was designed to inhibit spirochete populations and evaluate the effect upon periodontal destruction. Metronidazole was administered orally to four squirrel monkeys (100 mg/kg/bwt) for 17 days. After 3 days, marginal periodontitis was induced around bicuspids and molars by tying silk ligatures at the gingival margins. Subgingival plaque samples were taken baseline and 14 days after ligature placement. Dark-field microscopy quantitated motile forms, spirochetes, straight and curved rods, filament, cocci and fusiforms. Periodontal destruction was evaluated at 2 weeks by histometric analysis of connective tissue attachment, crestal alveolar bone and infiltrated connective tissue. Bacterial and histometric comparisons were made with experimental periodontitis data from four animals (control) which had not received metronidazole. Subgingival plaque prior to periodontitis induction was dominated by cocci, but fusiforms and straight rods were also present. Straight rods formed a greater proportion of the plaque which developed in metronidazole-receiving animals. The absence of spirochetes and motile rods contrasted with the control group where spirochetes were the predominant type. The total number of bacteria was also larger in the control animals. Histometric analysis showed that areas of infiltrated supracrestal connective tissue were similar in both groups. Loss of connective tissue attachment and alveolar bone was significantly less in experimental animals, and the latter values did not differ significantly from baseline dimensions. The results indicated that the subgingival bacterial populations which developed during metronidazole administration did not result in an experimental periodontitis.

Self-applied treatments in the management of dentine hypersensitivity.

A summary of the research on the different self-applied treatments for hypersensitive dentine provides some support for several agents but invalidates others. This is true for toothpastes, mouthwashes and gels. Direct comparison of studies is difficult because the materials and methods used are different. In addition, the size of patient groups, and methods of stimulation and assessment of the evoked pain reaction are different. Therefore our concept of the efficacy of self-applied treatment is not so much based on a homogeneous pool of data, but rather on a collection of individual studies. If we subtract from these data sets those based on obviously older ways of evaluating efficacy, we are left with surprisingly few studies that properly assess the efficacy of compounds suited to self-applied treatment. Therefore, guidelines should be established for testing such compounds, and publication of the data sets should depend on proper use of such designs. Stimuli, design and pain assessment should be standardized. In addition, patient recruitment could be defined better in relation to criteria for inclusion. Another area of concern is the pretreatment history of the hypersensitive teeth, because some teeth will become hypersensitive during the observation period, whilst others, which were hypersensitive, will spontaneously become insensitive. Therefore one should know the rate of spontaneous change in tooth sensitivity levels in each patient, in order not to assign treatment effects to teeth that would have lost their sensitivity anyway.

Comparison of serological and DNA probe analyses for detection of suspected periodontal pathogens in subgingival plaque samples.

Several methods are currently being used to identify specific bacteria in dental plaque, namely direct culture, serological techniques and DNA probes. Culture methods are labour-intensive, dependent on the viability of the cells, and require fastidious growth conditions. Serological and DNA probes allow rapid strain-specific identification of periodontal pathogens with limited effort. The purpose of the present study was to compare results from serological and DNA probes in assessing and quantitating the presence of three suspected periodontal pathogens in subgingival plaque: Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and Bact. intermedius. Subgingival bacterial samples were obtained from 4 periodontal sites of each of 13 patients with untreated moderate to advanced adult periodontitis. Samples were taken using 2 paper points that were simultaneously inserted for 10 s to the bottom of the periodontal pockets. The plaque from one paper point was analysed by immunofluorescence using monoclonal antibodies. The other sample was analysed by species-specific cloned DNA probes. The number of bacteria per millilitre was calculated for both methods, and used for comparisons of results obtained with the two techniques. Results from indirect immunofluorescence and DNA hybridization analyses were negative for A. actinomycetemcomitans across all samples. Fluorescence did not detect bacteria at levels lower than 10(4), while the DNA probes identified organisms at levels of 10(3). Similar numbers of samples positive for Bact. gingivalis were obtained with either method (p = 0.227), and the results were not independent. A significantly greater proportion of Bact. intermedius-positive samples was detected by immunofluorescence (p = 0.0039), and the results of immunofluorescence and DNA hybridization were independent.(ABSTRACT TRUNCATED AT 250 WORDS)

Episodic probing attachment loss versus pocket depth: bacterial morphotype associations.

Marginal periodontitis in humans is characterized by phases of clinical disease progression, which are interspersed between periods of quiescence. The purpose of the present study was to compare subgingival bacterial populations from periodontal sites undergoing episodic probing attachment loss with bacterial populations from non-progressing lesions. Probing depth and attachment levels were measured in 10 adult patients at baseline, and every 30 days thereafter for 10 months. Pairs of corresponding contralateral sites were identified where one site had lost probing attachment within the previous month (P) and the other site had not (C). Subgingival bacterial samples were obtained from these sites and analyzed using darkfield microscopy. Motile forms, spirochetes, curved and straight rods, filaments, coccoid cells, fusiforms, and the total number of bacteria were assessed. The results showed that median pocket depth and attachment change were statistically significantly greater in P-sites as compared to C-sites. There was no significant difference in bacterial populations between P- and C-sites (p greater than 0.15). Motile forms, spirochetes, and total number of bacteria were positively correlated with pocket depth in P-sites, while in C-sites the same was true only for curved rods. These results suggest that darkfield microscopy of subgingival bacteria in humans represents primarily pocket depth.

Correlations between periodontal tissue breakdown and cell populations.

The present study evaluated correlations between periodontal breakdown and cell populations during an experimental periodontitis. Periodontitis was induced by tying plaque retentive silk ligatures at the gingival margins of maxillary and mandibular bicuspids and molars of 4 squirrel monkeys. Periodontal destruction was evaluated at baseline, and 3, 7 and 14 days after ligature placement by measuring loss of connective tissue attachment and crestal alveolar bone. Cell populations were characterized at corresponding time points by counting polymorphonuclear leucocytes (PMNs), plasma cells and the total number of cells. At baseline, levels of connective tissue attachment and crestal alveolar bone were normal. At 3, 7 and 14 days, loss of attachment and loss of bone were statistically significant. At baseline PMNs and plasma cells were sparse. At 3, 7 and 14 days, the total number of cells and PMNs were statistically significantly increased compared to baseline. Periodontal tissue destruction was positively and strongly correlated with the number of PMNs. These correlations emphasize the potential role of PMNs during acute bursts of periodontal tissue destruction.

Effect of metronidazole on experimental periodontitis: cell population characteristics.

Systemic administration of metronidazole during an experimental periodontitis resulted in significantly less active tissue destruction compared to drug-free animals. However, the size of the inflammatory infiltrates in both groups was similar. The present study assessed cell populations within the infiltrates of metronidazole receiving and drug-free animals. In the experimental group, metronidazole was administered orally to 4 squirrel monkeys (100 mg/kg body weight per day) for 17 days. After 3 days, marginal periodontitis was induced around maxillary and mandibular bicuspids and molars by tying silk ligatures at the gingival margins. In 4 monkeys of the drug-free control group, periodontitis was induced around similar teeth. Biopsies of the gingiva representing 3, 7 and 14 days of experimental periodontitis were taken in both groups. The total number of cells and the number of polymorphonuclear leucocytes (PMN's) were counted on one-micron sections. At 3 days after ligature placement, there were numerically less total cells and PMN's in the metronidazole receiving experimental group. At 7 and 14 days the total number of cells and the number of PMN's was significantly greater in the drug-free control group, where more active periodontal breakdown had occurred. These results emphasize the potentially destructive role of PMN's in acute bursts of tissue destruction.