Root surface debridement and endotoxin removal.

OBJECTIVE: This study assessed associations between the number of standardized scaling strokes and the reduction of endotoxin on the root surface. BACKGROUND: Therapy of periodontally involved teeth attempts removal of accretions by scaling and root planing. The amount of mechanical therapy required to free the root surface from etiologic factors remains unknown. METHODS: Twenty-four extracted human caries-free single rooted teeth with at least 5 mm attachment loss were used. A region of interest (ROI) which contained subgingival calculus was defined on the root surface of each tooth. Standardized force instrumentation was applied using a force-measuring curet. Fifty working strokes were applied to every ROI. Forces applied were recorded. The force recordings were converted from Millivolts into Newtons (N). After every unit of 5 strokes, presence of calculus was evaluated and scaling debris was collected. Endotoxin concentration was determined in the debris samples. RESULTS: The endotoxin values for strokes 1-5 were statistically significantly greater than the values from all other stroke intervals. Complete calculus removal occurred after a mean of 9.3 strokes. The endotoxin concentration reached a minimal level with concentrations of 0.03-0.306 EU/ml after calculus removal was complete. CONCLUSION: These findings suggest that completion of calculus removal coincides with endotoxin levels associated with clinically healthy teeth.

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.

Systemic antimicrobial treatment and guided tissue regeneration. Clinical and microbiological effects in furcation defects.

The purpose of this investigation was to study the microbiota associated with furcation-involved teeth before and after treatment by the guided tissue regeneration procedure (GTR) with non-resorbable ePTFE membranes, and to evaluate the benefit of additional systemic antimicrobial therapy (ornidazole). Each of 10 patients contributed 1 pair of bilateral mandibular molars with comparable furcation defects. 5 defects were treated with a membrane and the active drug, 5 were treated without a membrane but with the active drug, 5 were treated with a membrane and a placebo, and 5 were treated with neither a membrane nor the active drug. Considerable differences were found in the healing response of furcation defects treated with or without the antimicrobial agent. More horizontal attachment gain and increase in bone density was obtained in patients receiving the active drug than in patients receiving the placebo. With 1 exception, all sites with increasing horizontal probing depth were found in patients of the placebo group. Treatment with membrane plus ornidazole resulted in 0.7 mm mean recession and -1.2 mm mean decrease in horizontal probing depth. Sites treated with membranes generally tended to be positive for 15 target micro-organisms more often than sites treated without a membrane. This was particularly evident for Fusobacterium, Prevotella intermedia and Actinomyces odontolyticus. Whereas GTR-treated sites were often already positive upon removal of the membrane, re-emergence of target organisms seemed to be more delayed in the conventionally-treated sites.

Reliability of single and double probing attachment level measurements.

Clarification of the reliability associated with probing attachment level measurements and with diagnostic rules derived from them is necessary to examine the potential of these measurements as reliable markers of the disease process and as an outcome measure in clinical treatment studies. The purpose of the present study was to describe and compare the longitudinal reliability of single and double probing attachment level measurable by estimating false positive and false negative rates. In 20 systemically healthy adults with untreated advanced adult periodontitis, probing attachment levels and probing depth were measured at 6 sites in all teeth at the start of the study, and every 30 days thereafter for 11 months. Attachment levels were double measured, using acrylic onlays providing reference points and an electronic pressure sensitive probe. Attachment loss from baseline of 2.5 mm or more was used to accept dynamic attachment loss. The statistical methods for the cross-sectional analysis included mean absolute differences between double measurements and cross-correlations. Longitudinal analyses, expressing estimates of diagnostic error rates were made using maximum likelihood methods. 5 measurement protocols were compared. The results showed that the mean absolute difference between replicate measurements was 0.095 mm in bicuspids and 0.107 mm in molars. The mean absolute differences decreased over time from 0. 128 mm in visit 3 to 0.08 mm in visit 7. Correlation coefficients for replicate measurements were higher than 0.98. In general, false positive rates were markedly lower (< or = 0.02) than false negative rates (< or = 0.31). The relative sample size required to obtain comparable statistical power, was minimized in premolars when using the first of 2 measurements or the mean of 2 measurements, and in molars when using the first of 2 measurements. The methodology used in the present study provides guidelines for designing clinical studies which maintain statistical power by balancing off examiner reliability and sample size.

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.

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.

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.

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.

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.

Numbers and vitality of leukocytes in pocket washings of untreated periodontitis lesions in humans utilizing a novel intracrevicular lavage technique.

The purpose of the present study was to develop an intracrevicular lavage technique, and to use it for assessment of the total number and % of vital leukocytes from untreated periodontitis pockets. A lavage device was developed, consisting of specially crafted cannulas, a vacuum pump and a charge amplifier. In vivo evaluations showed that there was a linear relationship between lavage time and lavage volume; 2-6 lavage samples were obtained from each of 20 patients with untreated advanced periodontitis, and the lavage time was measured in a subsample of 16 pockets. The lavage fluid was centrifuged, and the supernatant was separated from the cellular components. The cells were vital-stained using two methods, trypanblue exclusion method (TB) and ethidium-bromide fluorescein-diacetate stain (EB-FDA). Numbers of vital and non-vital leukocytes per sample were assessed using a Neubauer chamber. The number of erythrocytes per sample was evaluated using the same counting method. The results included 95 samples obtained from the 20 patients: 76% of all samples ranged in pocket depth between 4 and 8 mm. The lavage technique provided an overall mean lavage volume of 282.37 microliters in an average time of 16.44 seconds. The mean number of leukocytes per sample was 22.20 x 10(3) (TB) and 24.48 x 10(3) (EB-FDA). Percent vital leukocytes were 72.27 (TB) and 72.63 (EB-FDA). EB-FDA had a lower counting error than TB. The low erythrocyte counts per sample suggested that subgingival bleeding during sampling was negligible. Spearman correlation coefficients showed weak associations between pocket depth and leukocyte counts, % of vital leukocytes and erythrocytes. Due to the short sampling time this new intracrevicular sampling technique permits sampling of pockets before the tissue responds to the stimulus of the lavage device, and provides subgingival washings with high numbers of leukocytes.

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.

Factors determining the outcome of scaling and root planing.

Scaling and root planing are the predominant and recognized forms of periodontal therapy. They have been known for centuries, and have been investigated with increasing intensity since the turn of the century. Scaling and root planing aim at therapeutic changes of the "hard tissue lesion" at the root surface, in order to render it biologically acceptable to cells capable of attaching to it. Two major components of these root surface alterations are calculus and cementum alterations. Numerous studies have shown that scaling and root planing effectively removes subgingival deposits, and that this removal is seldom complete in deeper pockets. Even though beneficial clinical effects of scaling and root planing have been shown, it is unlikely that the full potential of healing is utilized today due to technical shortcomings. Several studies have shown that the design and dimensions of curets as used today are not optimal. These instruments are for many situations too big, subject to rapid dulling, and produce a smear layer. Chemical agents have been used to remove this layer with limited success. The therapist is a virtually unknown factor in the system of delivering scaling and root planing. A recent study showed that scaling and root planing forces used by different therapists on similar root surfaces varied by factors greater than 10. In addition, higher forces were shown to remove significantly more root substance. Apparently there is a large subjective component included in the delivery of scaling and root planing therapy. Even though scaling and root planing have been shown to be effective therapeutic procedures, many aspects require more research.

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.

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.