Periodontal repair after reduction of inflammation

Favorable Periodontal Regenerative Outcomes From Teeth With Presurgical Mobility: A Retrospective Study

BACKGROUND

The relevance of tooth mobility on periodontal healing is still controversial. The purpose of the present study was to evaluate the effect of presurgical tooth mobility on periodontal regenerative outcomes.

METHODS

The data in this study were derived from three randomized clinical trials which evaluated regenerative procedures. Sixty-four patients with one intraosseous periodontal defect each received one of the following treatments: guided tissue regeneration (GTR) using expanded polytetrafluoroethylene (ePTFE), GTR using a bioabsorbable membrane with or without demineralized freeze-dried bone allograft (DFDBA), or enamel matrix derivative with or without DFDBA. Probing depth (PD), clinical attachment level (CAL), recession (REC), and tooth mobility (TM) were recorded at baseline and 1 year after treatment by a calibrated examiner. The post-surgical follow-up and maintenance periods were designed to optimize plaque control. The teeth were grouped according to their baseline Miller index TM score. The grouping yielded 36 teeth with minimal mobility, score 0; 13 teeth with score 1; and 15 with score 2. The mean changes in PD, CAL and REC from baseline to 1 year were calculated for each group. One-way analysis of variance (ANOVA) was performed to assess differences between the tooth mobility groups considering changes in PD, CAL, and REC at 1 year.

RESULTS

The mean PD reduction from baseline to 1 year for teeth with TM score 0 was 3.67 mm; for TM score 1, 2.81 mm; and for score 2, 3.73 mm. The corresponding values for the gain in CAL were 2.73, 1.96, and 2.36 mm, respectively. According to ANOVA, the probing depth reductions and clinical attachment level gains found in each group were not statistically different, P= 0.218 and P= 0.252, respectively.

CONCLUSION

Within the limitations of this analysis, it can be concluded that interproximal, intraosseous defects of teeth with limited presurgical tooth mobility; i.e., teeth with Miller's Class 1 and 2 mobility, will respond favorably to regenerative therapy.

The effect of occlusal discrepancies on periodontitis. I. Relationship of initial occlusal discrepancies to initial clinical parameters

BACKGROUND

A causal relationship between occlusal discrepancies and periodontal disease has been postulated in the past. However, animal studies and clinical studies have not been able to clearly demonstrate or rule out this potential relationship.

METHODS

The records from a private practice limited to periodontics were reviewed to find patients who had complete periodontal examination records, including occlusal analysis, that were recorded at least 1 year apart. Patients who fit these criteria were divided into a group who had none of the recommended treatment (untreated n = 30), those that had only nonsurgical treatment (partially treated n = 18), and a control group that had complete all recommended treatment (surgically treated n = 41). The data for each tooth of each patient, including occlusal status, were placed in a database and analyzed using the generalized estimating equations (GEE) method to test for associations between initial occlusal discrepancies and various initial clinical parameters while adjusting for significant confounders.

RESULTS

Teeth with initial occlusal discrepancies were found to have significantly deeper initial probing depths (P < 0.0001), significantly worse prognoses (P < 0.0001), and significantly worse mobility than teeth without initial occlusal discrepancies. In addition, this association between initial occlusal discrepancies and initial periodontal condition was found to hold for various subsets considered as well, including posterior teeth only and when only patients with good oral hygiene were considered.

CONCLUSIONS

This study indicates that there is a strong association between initial occlusal discrepancies and various clinical parameters indicative of periodontal disease. Based on adjustments made for other known risk factors for periodontal disease, such as smoking, poor oral hygiene, etc., this study provides some evidence that occlusal discrepancy is an independent risk factor contributing to periodontal disease.

Occlusal trauma: effect and impact on the periodontium

This focused review is limited to a number of investigations in an attempt to specifically address the histological and clinical effects of excessive occlusal forces on the teeth and periodontium and to provide a basis of classification for this interaction. This review does not include the effects of occlusal forces on dental implants or dental prostheses/appliances.

Tooth mobility and periodontal disease

Tooth mobility (TM) is an important feature of periodontal disease. This is evidenced by the large number of devices and methods of TM assessment that have been developed and tested. TM had been considered and investigated as an indirect measure of the functional condition of the periodontium as well as possible aggravating co-factor for periodontal disease.

Transamidase and collagenase activity in healthy and diseased human gingival tissues

Transamidases are a class of calcium-dependent mammalian enzymes which cross-link proteins by catalyzing the formation of (gamma-glutamyl)-epsilon-lysine bonds. It is possible that these enzymes play an important anabolic role in tissue healing. This study was to quantitate transamidase activity in human gingival tissue and examine the relation between transmidase activity and degree of inflammation. Forty-four out of a total 120 collected human gingival specimens from healthy and diseased patients were selected based on histometric and microbiologic criteria. Specimens were minced and homogenized in 10 mM CaCl2 and then extracted for 30 min, in 50 mM tris-HCl buffer (pH 7.5) containing 100 mM CaCl2. Following low speed centrifugation at 4 degrees C, the supernatant solution was assayed for both transamidase and collagenase activities by radioactive amine incorporation, and digestion of tritiated collagen, respectively. Appreciable levels of transamidase and collagenase activities in healthy gingivae were found. These enzyme activities were significantly elevated in the diseased and healing tissues. Unlike other transamidases, calcium was required in the enzyme extraction process.

Cementum thickness and mesial drift

Cementum thickness increases uniformly with age, and questionably from functional stimulation due to tensional forces. Mesial drift of teeth results in tensional forces on distal root surfaces. This study evaluated whether there was any discernible effect on cementum thickness related to mesial drift in humans. The material consisted of maxillary and mandibular bicuspids and molars with their surrounding periodontia from 5 humans (mean age at death, 48.6 years). The teeth and tissues had been sectioned histologically in a mesio-distal plane, and the analysis for each tooth was done using 3 step-serial sections from the mid-buccolingual region. On the mesial and distal surface of each tooth, cementum thickness was measured in microns at 3 defined locations at a level representing the mid-point of root length for bicuspids and molars. Means from the measurements on mesial and distal surfaces were compared using descriptive and and inferential statistical methods. For each individual tooth analyzed, the cementum was thicker on the distal surface (range greater, 32-107%; mean, 69%). The statistical comparisons showed that cementum thickness on the distal surface was significantly greater for bicuspids (mesial, 135 microns: distal, 216 microns), molars (mesial, 154 microns: distal, 284 microns), and all teeth combined (mesial, 154 microns: distal, 284 microns). The magnitude of this difference became greater with increasing age. It was concluded that cementum thickness was markedly greater on the distal surfaces of teeth from adult humans, and that this may be due to functional stimulation from mesial drift over time.

A combination of platelet-derived and insulin-like growth factors enhances periodontal regeneration

The combination of platelet-derived growth factor (PDGF) and insulin-like growth factor one (IGF-1) has previously been shown to enhance repair of soft tissue wounds. Here we report initial observations following application of PDGF and IGF-1 to periodontitis-affected teeth in beagle dogs. 1 micrograms of PDGF and IGF-1 in an aqueous gel was applied to the root surfaces of test teeth following open flap debridement. Control sites received the gel alone. Block biopsies of the teeth and surrounding bone were taken 2 weeks after treatment. Histologic analyses of control specimens revealed a long junctional epithelial attachment, and no new bone or cementum formation. In contrast, growth factor treated sites exhibited significant amounts of new bone and cementum formation. A nearly continuous layer of osteoblasts lined the newly formed bone, and there was a dense cellular "front" at the coronal extent of the new bone. These preliminary results suggest that in vivo application of the combination of PDGF and IGF-1 may enhance regeneration of the periodontal structures.

Tetracycline therapy in patients with early juvenile periodontitis

Tetracycline therapy, when used in conjunction with surgery or root planing, has been shown to be effective in controlling the progression of juvenile periodontitis. However, the ability of tetracycline alone to control the disease has not been assessed. The present study evaluated the effects of tetracycline therapy, with supragingival plaque control, on clinical attachment levels and radiographic bone height in patients with clinical and radiographic evidence of juvenile periodontitis. The four patients (mean age 15.2 +/- 0.3 yrs) each demonstrated loss of attachment of greater than or equal to 2 mm at one or more probing sites and had accompanying radiographic evidence of early localized bone loss. Following an initial clinical evaluation consisting of pocket depths, attachment levels and standardized radiographs, the patients received systemic tetracycline therapy (1 gm/day for three to six weeks) and oral hygiene instruction. At the completion of antibiotic therapy, patients received a supragingival professional prophylaxis every two weeks for three months, whereupon the initial evaluation was repeated. On comparing the initial and three-month clinical and radiographic data, there were significant decreases in clinical and radiographic measurements. For a total of 85 affected probing sites around 26 teeth, 79% decreased in pocket depth by greater than or equal to 2 mm (with no sites increasing in pocket depth) and 69% gained clinical attachment (with only one site losing attachment of 1 mm). Radiographic measurements revealed an increase in both the height and area of coronal alveolar bone. The findings indicated that six weeks of systemic tetracycline therapy combined with supragingival plaque control was effective in the initial control of early juvenile periodontitis.

Correlation of histometric, microbial, and clinical indicators of periodontal disease status before and after root planing

Effective diagnosis and treatment of periodontal disease requires accurate evaluation of disease status before and after treatment. This study evaluated relationships among multiple parameters that have been used for periodontal disease evaluation. A total of 61 initially deep (greater than or equal to 6 mm) interproximal pockets from 16 patients examined before and after a 3-week course of root planing therapy were evaluated for probing depth, bleeding on probing, darkfield and cultural characterization of subgingival plaque, and histometric indices of infiltrated connective tissue (ICT) and mature plasma cell infiltrate. 36 sites were evaluated before treatment, and 25 after treatment. A comparison of mean scores for pre-treatment sites versus post-treatment sites indicated that there was an average improvement in most disease-related parameters. However, patterns of significant correlations among the parameters differed markedly. Motile bacteria enumerated by darkfield microscopy were significantly correlated with ICT and plasma-cell populations before, but not after treatment. In contrast, probing depth and populations of black pigmented Bacteroides (BPB's), principally B. gingivalis, were significantly correlated with ICT after, but not before, treatment. Bleeding on probing was not significantly correlated with ICT levels before or after treatment. This suggests that different sets of parameters should be used for evaluating periodontal disease status before or after treatment. Our data further suggest that B. gingivalis populations may be related to delayed healing of deep periodontal lesions after instrumentation.

The relative importance of plaque and occlusion in periodontal disease

A series of studies has investigated interactions between periodontal trauma and marginal periodontitis in relation to the initiation, progression and treatment of periodontal disease. Lesions of trauma in the periodontal ligament do not initiate the loss of connective tissue attachment characteristic of marginal periodontitis. Studies conducted in squirrel monkeys and beagle dogs in which jiggling forces were superimposed upon an established marginal periodontitis reported increased loss of alveolar bone, but the accelerated loss of attachment which occurred in the dog model did not occur in the monkey model. In order to clarify the relative importance of inflammation and tooth mobility in the treatment of advanced periodontal disease, periodontal responses were evaluated after removing combinations of traumatic and inflammatory components. Elimination of trauma in the presence of existing marginal inflammation did not reduce tooth mobility or increase bone volume. Osseous regeneration and decreased tooth mobility occurred after resolving both components; however, similar findings occurred after resolving inflammation in the presence of continued tooth mobility. After resolution of inflammation, remaining tooth mobility does not result in increased loss of connective tissue attachment. On a clinical level for periodontal disease treatment, the findings place decreased emphasis upon management of tooth mobility and increased emphasis upon resolution of marginal inflammation.

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.

Microbial populations and active tissue destruction in experimental periodontitis

Although specific subgingival microflora are being associated with active tissue destruction in periodontitis, little information exists on the relationship between subgingival flora and histological evidence of tissue destruction. The present study was undertaken to explore these relationships during experimental marginal periodontitis in squirrel monkeys. In 4 squirrel monkeys, experimental periodontitis was induced around bicuspids and molars using silk ligatures. The buccal part of the subgingival ligature was removed for bacterial sampling 3, 7, and 14 days after ligature placement. Dark-field microscopy was used to quantify motile forms, spirochetes, straight and curved rods, filaments, cocci and fusiforms. Subgingival plaque prior to periodontitis induction was dominated by cocci, but fusiforms and straight rods were also present. Spirochetes, filaments, curved rods and motile forms were absent. 3 days after induction of periodontitis, there were marked increases in spirochetes, motile forms, filaments, curved and straight rods. The proportions of coccoids and fusiforms decreased. The bacterial proportions stayed at approximately the same levels through 7 and 14 days. Histometric quantification of periodontal destruction showed loss of connective tissue attachment and crestal alveolar bone. A positive correlation was found between periodontal tissue destruction and both total number of subgingival bacteria and spirochetes.

Orthodontic extrusion of single-rooted teeth affected with advanced periodontal disease

Orthodontic extrusion of teeth with advanced periodontal disease was evaluated in beagle dogs. Surgical destruction of one third to one half of the attachment apparatus and the inducement of chronic periodontal disease was accomplished on the hemisected mesial roots of the mandibular premolars. The roots on one side of the mandible were extruded toward a cemented stainless steel bridge by means of elastics providing 20 to 25 gm of force. The force was examined daily. When extruded teeth came into contact with the bridge, they were ligated in place for 21 days of stabilization. Clinical results showed that control teeth maintained their position and signs of advanced periodontitis. Extruded teeth had shallower pocket depths, less gingival inflammation, and no bleeding on probing. Radiographic evaluation showed no demonstrable changes in the control teeth. Early in the extrusion process, the teeth appeared to be avulsed, with more than three fourths of the root coronal to the alveolar crest. After stabilization, approximately 2 mm of new bone was seen coronal to the original alveolar crest, and the periapical areas had filled in as well. This bone formation was verified histologically. The extruded teeth had an intact attachment apparatus with all components in the same relative position on the teeth as in the controls. However, a shallower sulcus and less gingival inflammation were noted in the extruded teeth. There were statistically significant findings of a wider periodontal ligament space, greater cementum width, and increased bone height in the crestal areas of extruded teeth. Extruded teeth also had less cementum width and greater new bone formation at the apex.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of topical application of citric acid in the treatment of furcation involvement in human lower molars

Improvement of new attachment procedures using topically applied citric acid was tested in human beings. Furcation involvement and the adjacent proximal area were surgically exposed. Saline was used as placebo drug. Baseline pocket depth and attachment levels were scored prior to surgery and bone level recorded at the time of surgery. After 1, 3 and 6 months, the clinical parameters were re-scored and at that time, a re-entry operation allowed a new measurement of the bone level. In the post-operative experimental periods, there was an improvement of all clinical parameters in both the control and experimental groups. Pocket depth reduction was consistent; the gain in the attachment level compared to the baseline examination in the experimental group and the improvement in the bone height level were statistically significant within the 6-month post-operative interval; however, in both the furcation and proximal areas, no statistically significant differences could be detected on comparing experimental and control groups.

Effects of gold salts on experimental periodontitis. I. Histometric evaluation of periodontal destruction

Systemic administration of gold salts for treatment of arthritis is thought to limit tissue destruction through alteration of inflammatory cell function. The present study ascertained if gold salts could modify the tissue destruction associated with an experimental marginal periodontitis. Therapeutic levels of serum gold salts were established in four squirrel monkeys (experimental) by intramuscular injection of Myochrisine (gold sodium thiomalate 25 mg/ml) at 5 mg/kg/body weight at 4-day intervals for 12 days. Marginal periodontitis was then induced around mandibular bicuspids by tying plaque retentive ligatures at the gingival margins. Periodontitis was induced around corresponding teeth in four control animals which had not received gold salts. Serum levels of gold salts were maintained in experimental animals, and all animals were killed 2 weeks after induction of periodontitis. Progression of periodontitis was evaluated histometrically on step-serial sections, and the results analyzed statistically. Specimens from gold-receiving animals had significantly smaller areas of infiltrated supracrestal connective tissue, and less loss of connective tissue attachment and coronal alveolar bone. Quantitation of total plaque around the ligatures showed no differences; however, there was less plaque located apical to the ligatures in gold-receiving specimens. Although the study design did not permit identification of the relative importance of cellular or microbial factors, it was concluded that administration of systemic gold salts was associated with significantly less periodontal destruction.

Effect of periodontal trauma upon intrabony pockets

Conflicting results have been reported regarding the effect of periodontal trauma upon progression of periodontitis. In these studies, different initial pocket morphologies were present. This study investigated the effect of trauma superimposed upon existing intrabony pockets. Localized intrabony pockets were produced adjacent to the mesial and distal surfaces of the mandibular third bicuspids in 10 squirrel monkeys. Two animals were killed after 10 weeks of periodontitis. In four (experimental) of the remaining eight animals, mesio-distal jiggling of the third bicuspid was begun 10 weeks after induction of periodontitis, and continued for another 10 weeks. The other four animals (control) were killed 20 weeks after initiation of periodontitis. Step-serial histologic sections were selected from experimental and control specimens and analyzed for loss of connective tissue attachment, loss of crestal alveolar bone and percentage of bone in the coronal interproximal periodontium. When corresponding dimensions from experimental and control surfaces were compared statistically, there were no differences in loss of connective tissue attachment but a greater loss of bone had occurred in specimens with the combination of periodontitis and trauma. In addition, there was a marked difference in osseous morphology between the experimental and control specimens. It was concluded that trauma superimposed upon existing intrabony pockets increased loss of alveolar bone and altered osseous morphology, but did not affect the loss of connective tissue attachment.

Osseous repair in the presence of active tooth hypermobility

The present investigation was undertaken to evaluate the periodontal response after resolution of inflammation in a situation of established marginal periodontitis, but in the presence of active, continued tooth hypermobility. Periodontitis was induced unilaterally around mandibular second and third bicuspids in 4 squirrel monkeys by tying plaque retentive silk ligatures at the gingival margins. Jiggling trauma to the periodontium between these bicuspids was begun 5 weeks later and continued for the remaining 20 weeks. Ligatures were removed 15 weeks after placement, whereupon regular oral hygiene was begun and continued. Periodontitis and trauma were produced around the corresponding contralateral teeth (control) so that the interproximal area represented the situation immediately prior to ligature removal. Infiltrated connective tissue, loss of connective tissue attachment and alveolar bone, and percentage of bone were determined histometrically for each coronal interproximal periodontium. In control specimens, 58% of the supracrestal tissue was infiltrated with inflammatory cells compared to 19% in experimental specimens. There were no differences in levels of connective tissue attachment or crestal alveolar bone. However, bone repair occurred in the experimental specimens which increased bone volume from 11 to 18% (P less than 0.05). It was concluded that osseous repair occurred in the presence of active, continued tooth hypermobility after resolution of inflammation.

Effects of oral hygiene on the results of periodontal surgery in beagle dogs with artificially created defects

The effect of oral hygiene on periodontal surgery was evaluated clinically, radiographically and histologically during 24 months. In 13 beagle dogs artificial periodontal defects were created around the second, third and fourth premolars of the mandible. One week after removal of the plaque retention ligatures, periodontal surgery consisting of mucoperiosteal flaps and osseous recontouring was performed. Postoperatively, plaque accumulation was prevented by daily application of a 2% chlorhexidine solution for 2 weeks and daily toothbrushing for the next 2 weeks. Toothbrushing was continued in seven dogs; oral hygiene was discontinued in the other six. All dogs were scaled and polished at 1, 6, 12 and 18 months after surgery. Plaque accumulation in the nonbrushed dogs resulted in a heavy inflammation of the periodontium. Probing depths that had been reduced by the surgery increased and subsequently the clinical attachment level changed into a more apical level compared to the brushed dogs. Histometrically, however, no difference in attachment level could be recorded, indicating that oral hygiene did not affect the attachment level in the 2 years after surgery. It appears that oral hygiene stimulated bone formation and that the periodontal tissues had not matured in the 2 years after surgery.

A periodontal attachment mechanism without alveolar bone. Case report

A 22-year-old black male was referred for periodontal therapy because of radiographic evidence of advanced bone loss associated with the posterior teeth. Clinical examination revealed gingivitis, normal sulcus depths, and minimal loss of clinical attachment. Complete blood counts, serum chemistry, and neutrophil function were within normal limits. Histological, histochemical and ultrastructural analysis of an extracted tooth revealed no loss of attachment; large areas of the cementum were collagen-poor and, ultrastructurally, resembled afibrillar cementum. It is proposed that the periodontal attachment mechanism present in this case was associated with a localized failure in normal periodontal development.

Effect of root surface alterations on periodontal healing. I. Surgical denudation

The present study was undertaken to evaluate the effect of root surface denudation on periodontal healing. Twelve teeth, distributed in four squirrel monkeys, were extracted and reimplanted after surgically denuding the coronal root surface of connective tissue fibers and cementum by root planing. The reimplantation schedule provided three teeth for histologic analysis at 1, 3, 7 and 21 days after reimplantation. One day after reimplantation a zone of fibrin enmeshing erythrocytes and inflammatory cells was interposed between th root surface and the remaining periodontal fibers attached to the alveolar bone. Epithelium migrated rapidly along the denuded root, had reached the alveolar crest at 3 days, and was within the ligament space at 7 days. At 21 days, the epithelium was at the apical limit of root instrumentation, which corresponded to the level of attached connective tissue fibers on the root surface. No evidence of new connective tissue attachment was observed on the denuded root surface. It was concluded that the absence of fibers on the root surface resulted in apical migration of the epithelium, and precluded formation of new connective tissue attachment.

Factors influencing periodontal repair and regeneration

The purpose of the present study was to evaluate independently the regeneration capacity of a reduced periodontium, and the potential for new connective tissue attachment to a periodontally exposed root surface. A reduced periodontium was produced around a maxillary central incisor in two Rhesus monkeys using orthodontic elastics. The regeneration capacity of this reduced peridontium was investigated by extracting the periodontally involved tooth and transplanting into the socket the contralateral incisor which had a normal periodontium. The potential for new connective tissue attachment to a periodontally exposed root surface was evaluated by transplanting an exposed root into a normal periodontium. These exposed roots were the incisors extracted from the reduced peridontium. Control specimens were obtained by extracting and reimplanting or transplanting the remaining maxillary and mandibular incisors. Forty days after the experimental procedures, block sections were removed and prepared for histologic analysis. The exposed root surface that had been put into the normal periodontium was lined with epithelium interposed between root surface and alveolar bone. The normal root surface that had been put into the reduced periodontium had connective tissue reattachment in the periodontal ligament and supracrestal regions. Areas of ankylosis and root resorption were present in all specimens, as was new cementum in the periodontal ligament region. The results indicated that root surface alterations, rather than presence of a reduced periodontium, inhibited new connective tissue attachment.

Clinico-pathologic correlation of 385 lesions of marginal destructive periodontitis

THIS STUDY investigated the relationship between the degree of periodontal destruction present in advanced periodontal lesions and consistently associated infiltrates of lymphocytes and/or plasma cells. A total of 385 biopsy specimens were obtained from the depths of pockets during routine periodontal surgery. The selected lesions were in "established" or "advanced" stages and were classified according to pocket depth as Class I (4-6 mm) or Class II (7-10 mm). The infiltrates attached to the cementum, bone, or lining the pocket soft tissue wall were classified in five types according to the distribution of lymphocytes, plasmocytes, and neutrophils. Statistical evaluation of the findings demonstrates a strong, significant relationship (P less than 0.001) between the degree of destruction of supporting periodontal tissues (Class II) and the predominance of plasma cells in the infiltrate (Type a). A weaker significant correlation (P less than 0.02) was found between predominant lymphocytic populations (Type b) and Class I lesions. The assumption was made that local, specific, cellular infiltrates reflecting immunologic mechanisms are associated with the degree of periodontal destruction in humans.

The behavior of angular bony defects following reduction of inflammation

This study was designed to quantitate the changes in experimental angular bony defects and the surrounding tissues following the removal of irritants associated with marginal periodontitis. Plaque retentive ligatures were placed around the mandibular second bicuspids in each of four squirrel monkeys. Ten weeks later the ligatures were removed and mechanical cleaning was implemented. At the same time, ligatures were placed on the contralateral (control) bicuspids. After 10 weeks the monkeys were sacrificed and the tissues prepared for analysis. The control tissues represented the state of the periodontium immediately prior to ligature removal and the implementation of 10 weeks of mechanical cleaning. Histometric analyses revealed a reduction from 68 to 14% in the inflammatory cell infiltrate present in the supracrestal connective tissue following ligature removal and plaque control. Concomitant with this decrease was a 50% increase (P < 0.01) in the amount of bone present in the coronal periodontium. There was bone repair at the crest and along the angular defect but there was not a total regeneration of the lesion. These tissue changes were accompanied by a reduction in tooth mobility and a reformation of the gingival architecture although there was no new attachment. It appears that there is a potential for bone repair in these angular defects without an alteration in the connective tissue attachment level.